Volumetric analysis and hydrologic characterization of a modern debris flow near Yucca Mountain, Nevada

USGS Publications Warehouse

Coe, J.A.; Glancy, P.A.; Whitney, J.W.

1997-01-01

On July 21 or 22, 1984, debris flows triggered by rainfall occurred on the southern hillslope of Jake Ridge, about 6 km east of the crest of Yucca Mountain, Nevada. Rain gages near Jake Ridge recorded 65 mm and 69 mm on July 21, and 20 mm and 17 mm on July 22. Rates of rainfall intensity ranged up to 73 mm/h on the twenty-first, and 15 mm/h on the twenty-second. Digital elevation models with 2.0 m grid-node spacing, measured from pre-storm and post-storm aerial stereo-photographs, were used to map hillslope erosion and the downslope distribution of debris. Volumetric calculations indicate that about 7040 m3 of debris was redistributed on the 49,132 m2 hillslope study area during the two-day storm period. About 4580 m3 (65%) of the eroded sediment was deposited within the study area and the remaining 35% was deposited outside the study area in a short tributary to Fortymile Wash and in the wash itself. The maximum and mean depths of erosion in the study area were about 1.8 m and 5 cm, respectively. The mean depths of erosion on the upper and middle hillslope were 27 cm and 4 cm, respectively. The mean depth of deposition on the lower hillslope was 16 cm. Analysis of the values of cumulative precipitation in the context of the precipitation-frequency atlas of the National Oceanic and Atmospheric Administration indicates that precipitation from the main storm on July 21 was more than double that expected, on average, once during a 100-year period. The relations of precipitation intensity/duration, developed from data recorded at a nearby precipitation gage, indicate a storm interval of 500 years or greater. The amount of erosion caused by such a storm is primarily dependent on three variables: storm intensity, development of the drainage network on the hillslope, and the amount of available colluvium. Additionally, the erosive ability of successive storms of equal intensity will decrease because such storms would tend to progressively isolate and reduce the amount of colluvium available. The preservation of Pleistocene deposits on hillslopes of Yucca Mountain, in general, indicates that erosional events that strip 5% of the available hillslope colluvium must be quite rare. We conclude that the recurrence interval of an erosional event comparable to the July, 1984 event is probably much longer than 500 years.

SToRM: A numerical model for environmental surface flows

USGS Publications Warehouse

Simoes, Francisco J.

2009-01-01

SToRM (System for Transport and River Modeling) is a numerical model developed to simulate free surface flows in complex environmental domains. It is based on the depth-averaged St. Venant equations, which are discretized using unstructured upwind finite volume methods, and contains both steady and unsteady solution techniques. This article provides a brief description of the numerical approach selected to discretize the governing equations in space and time, including important aspects of solving natural environmental flows, such as the wetting and drying algorithm. The presentation is illustrated with several application examples, covering both laboratory and natural river flow cases, which show the model’s ability to solve complex flow phenomena.

SToRM: A Model for 2D environmental hydraulics

USGS Publications Warehouse

Simões, Francisco J. M.

2017-01-01

A two-dimensional (depth-averaged) finite volume Godunov-type shallow water model developed for flow over complex topography is presented. The model, SToRM, is based on an unstructured cell-centered finite volume formulation and on nonlinear strong stability preserving Runge-Kutta time stepping schemes. The numerical discretization is founded on the classical and well established shallow water equations in hyperbolic conservative form, but the convective fluxes are calculated using auto-switching Riemann and diffusive numerical fluxes. Computational efficiency is achieved through a parallel implementation based on the OpenMP standard and the Fortran programming language. SToRM’s implementation within a graphical user interface is discussed. Field application of SToRM is illustrated by utilizing it to estimate peak flow discharges in a flooding event of the St. Vrain Creek in Colorado, U.S.A., in 2013, which reached 850 m3/s (~30,000 f3 /s) at the location of this study.

Storm surges and climate change implications for tidal marshes: Insight from the San Francisco Bay Estuary, California, USA

USGS Publications Warehouse

Thorne, Karen M.; Buffington, Kevin J.; Swanson, Kathleen; Takekawa, John Y.

2013-01-01

Tidal marshes are dynamic ecosystems, which are influenced by oceanic and freshwater processes and daily changes in sea level. Projected sea-level rise and changes in storm frequency and intensity will affect tidal marshes by altering suspended sediment supply, plant communities, and the inundation duration and depth of the marsh platform. The objective of this research was to evaluate if regional weather conditions resulting in low-pressure storms changed tidal conditions locally within three tidal marshes. We hypothesized that regional storms will increase sea level heights locally, resulting in increased inundation of the tidal marsh platform and plant communities. Using site-level measurements of elevation, plant communities, and water levels, we present results from two storm events in 2010 and 2011 from the San Francisco Bay Estuary (SFBE), California, USA. The January 2010 storm had the lowest recorded sea level pressure in the last 30 years for this region. During the storm episodes, the duration of tidal marsh inundation was 1.8 and 3.1 times greater than average for that time of year, respectively. At peak storm surges, over 65% in 2010 and 93% in 2011 of the plant community was under water. We also discuss the implications of these types of storms and projected sea-level rise on the structure and function of the tidal marshes and how that will impact the hydro-geomorphic processes and marsh biotic communities.

Benthic habitat and fish assemblage structure from shallow to mesophotic depths in a storm-impacted marine protected area

NASA Astrophysics Data System (ADS)

Abesamis, Rene A.; Langlois, Tim; Birt, Matthew; Thillainath, Emma; Bucol, Abner A.; Arceo, Hazel O.; Russ, Garry R.

2018-03-01

Baseline ecological studies of mesophotic coral ecosystems are lacking in the equatorial Indo-West Pacific region where coral reefs are highly threatened by anthropogenic and climate-induced disturbances. Here, we used baited remote underwater video to describe benthic habitat and fish assemblage structure from 10 to 80 m depth at Apo Island, a well-managed marine protected area in the Philippines. We conducted surveys 2 yr after two storms (in 2011 and 2012) caused severe damage to shallow coral communities within the no-take marine reserve (NTMR) of Apo Island, which led to declines in fish populations that had built up over three decades. We found that hard coral cover was restricted to < 40 m deep in the storm-impacted NTMR and a nearby fished area not impacted by storms. Benthic cover at mesophotic depths (> 30 m) was dominated by sand/rubble and rock (dead coral) with low cover of soft corals, sponges and macroalgae. Storm damage appeared to have reached the deepest limit of the fringing reef (40 m) and reduced variability in benthic structure within the NTMR. Species richness and/or abundance of most trophic groups of fish declined with increasing depth regardless of storm damage. There were differences in taxonomic and trophic structure and degree of targeting by fisheries between shallow and mesophotic fish assemblages. Threatened shark species and a fish species previously unreported in the Philippines were recorded at mesophotic depths. Our findings provide a first glimpse of the benthic and fish assemblage structure of Philippine coral reef ecosystems across a wide depth gradient. This work also underscores how a combination of limited coral reef development at mesophotic depths close to shallow reefs and severe habitat loss caused by storms would result in minimal depth refuge for reef fish populations.

Dune migration in a steep, coarse-bedded stream

USGS Publications Warehouse

Dinehart, Randy L.

1989-01-01

During 1986 and 1987, migrating bed forms composed of coarse sand and fine gravel (d50=1.8 to 9.1 mm) were documented in the North Fork Toutle River at Kid Valley, Washington, at flow velocities ranging from 1.6 to 3.4 m s−1 and depths of 0.8 to 2.2 m. The bed forms (predominantly lower regime dunes) were studied with a sonic depth sounder transducer suspended in the river at a stationary point. Twelve temporal depth-sounding records were collected during storm runoff and nearly steady, average streamflow, with record durations ranging from 37 to 261 min. Waveform height was defined by dune front heights, which ranged from 12 to 70 cm. A weak correlation between flow depth and the standard deviation of bed elevation was noted. Dune front counts and spectral analyses of the temporal records showed that dune crests passed the observation point every 2 to 5 min. Dunes were often superposed on larger bed forms with wave periods between 10 and 30 min. Gradual changes in waveform height and periodicity occurred over several hours during storm runoff. The processes of dune growth and decay were both time-dependent and affected by changes in streamflow. Rates of migration for typical dunes were estimated to be 3 cm s−1, and dune wavelengths were estimated to be 6 to 7 m.

Evaluation of the impact of storm event inputs on levels of gross primary production and respiration in a drinking water reservoir

NASA Astrophysics Data System (ADS)

Samal, N. R.; Pierson, D. C.; Staehr, P. A.; Pradhanang, S. M.; Smith, D. G.

2013-12-01

Episodic inputs of dissolved and particulate material during storm events can have important effects on lake and reservoir ecosystem function and also impact reservoir drinking water quality. We evaluate the impacts of storm events using vertical profiles of temperature, dissolved oxygen, turbidity, conductivity and chlorophyll automatically collected at 6 hour intervals in Ashokan Reservoir, which is a part of the New York City drinking water supply. Storm driven inputs to the reservoir periodically result in large input of suspended sediments that result in reservoir turbidity levels exceeding 25 NTU, and substantial reductions in the euphotic depth. Dissolved materials associated with these same storms would be expected to stimulate bacterial production. This study involves the use of a conceptual model to calculate depth specific estimates of gross primary production (GPP) and ecosystem respiration (R) using three years of data that included 777 events that increased reservoir turbidity levels to over 25 NTU. Using data from before, during and after storm events, we examine how the balance between GPP and R is influenced by storm related increases in turbidity and dissolved organic matter, which would in turn influence light attenuation and bacterial production. Key words: metabolism, primary production, GPP, respiration, euphotic depth, storm event, reservoir

Limitations and potential of satellite imagery to monitor environmental response to coastal flooding

USGS Publications Warehouse

Ramsey, Elijah W.; Werle, Dirk; Suzuoki, Yukihiro; Rangoonwala, Amina; Lu, Zhong

2012-01-01

Storm-surge flooding and marsh response throughout the coastal wetlands of Louisiana were mapped using several types of remote sensing data collected before and after Hurricanes Gustav and Ike in 2008. These included synthetic aperture radar (SAR) data obtained from the (1) C-band advance SAR (ASAR) aboard the Environmental Satellite, (2) phased-array type L-band SAR (PALSAR) aboard the Advanced Land Observing Satellite, and (3) optical data obtained from Thematic Mapper (TM) sensor aboard the Land Satellite (Landsat). In estuarine marshes, L-band SAR and C-band ASAR provided accurate flood extent information when depths averaged at least 80 cm, but only L-band SAR provided consistent subcanopy detection when depths averaged 50 cm or less. Low performance of inundation mapping based on C-band ASAR was attributed to an apparent inundation detection limit (>30 cm deep) in tall Spartina alterniflora marshes, a possible canopy collapse of shoreline fresh marsh exposed to repeated storm-surge inundations, wind-roughened water surfaces where water levels reached marsh canopy heights, and relatively high backscatter in the near-range portion of the SAR imagery. A TM-based vegetation index of live biomass indicated that the severity of marsh dieback was linked to differences in dominant species. The severest impacts were not necessarily caused by longer inundation but rather could be caused by repeated exposure of the palustrine marsh to elevated salinity floodwaters. Differential impacts occurred in estuarine marshes. The more brackish marshes on average suffered higher impacts than the more saline marshes, particularly the nearshore coastal marshes occupied by S. alterniflora.

Gray whale and walrus feeding excavation on the Bering Shelf, Alaska.

USGS Publications Warehouse

Nelson, C.H.; Johnson, K.R.; Barber, J.H.

1987-01-01

The gray whales (average mouth length, 2.0 m), when suction feeding on infaunal amphipods, create shallow pits in the sea floor, typically 2.5m x 1.5m x 10cm deep, which are distinct and mappable on sidescan sonographs. Similarly, walrus, when foraging for shallow clams, create long, linear feeding furrows that average 47 x 0.4 x 0.1m (length-width-depth). The whale feeding pits are commonly enlarged and oriented by seasonal storm-related scour. Walrus-feeding features are smaller, formed in higher-energy environments, and modified more rapidly than whale-feeding pits. -from Authors

Geophysical Inversion with Adaptive Array Processing of Ambient Noise

NASA Astrophysics Data System (ADS)

Traer, James

2011-12-01

Land-based seismic observations of microseisms generated during Tropical Storms Ernesto and Florence are dominated by signals in the 0.15--0.5Hz band. Data from seafloor hydrophones in shallow water (70m depth, 130 km off the New Jersey coast) show dominant signals in the gravity-wave frequency band, 0.02--0.18Hz and low amplitudes from 0.18--0.3Hz, suggesting significant opposing wave components necessary for DF microseism generation were negligible at the site. Both storms produced similar spectra, despite differing sizes, suggesting near-coastal shallow water as the dominant region for observed microseism generation. A mathematical explanation for a sign-inversion induced to the passive fathometer response by minimum variance distortionless response (MVDR) beamforming is presented. This shows that, in the region containing the bottom reflection, the MVDR fathometer response is identical to that obtained with conventional processing multiplied by a negative factor. A model is presented for the complete passive fathometer response to ocean surface noise, interfering discrete noise sources, and locally uncorrelated noise in an ideal waveguide. The leading order term of the ocean surface noise produces the cross-correlation of vertical multipaths and yields the depth of sub-bottom reflectors. Discrete noise incident on the array via multipaths give multiple peaks in the fathometer response. These peaks may obscure the sub-bottom reflections but can be attenuated with use of Minimum Variance Distortionless Response (MVDR) steering vectors. A theory is presented for the Signal-to-Noise-Ratio (SNR) for the seabed reflection peak in the passive fathometer response as a function of seabed depth, seabed reflection coefficient, averaging time, bandwidth and spatial directivity of the noise field. The passive fathometer algorithm was applied to data from two drifting array experiments in the Mediterranean, Boundary 2003 and 2004, with 0.34s of averaging time. In the 2004 experiment, the response showed the array depth varied periodically with an amplitude of 1 m and a period of 7 s consistent with wave driven motion of the array. This introduced a destructive interference which prevents the SNR growing with averaging time, unless the motion is removed by use of a peak tracker.

Assessing the Reliability of Regional Depth-Duration-Frequency Equations for Gauged and Ungauged Sites

NASA Astrophysics Data System (ADS)

Castellarin, A.; Montanari, A.; Brath, A.

2002-12-01

The study derives Regional Depth-Duration-Frequency (RDDF) equations for a wide region of northern-central Italy (37,200 km 2) by following an adaptation of the approach originally proposed by Alila [WRR, 36(7), 2000]. The proposed RDDF equations have a rather simple structure and allow an estimation of the design storm, defined as the rainfall depth expected for a given storm duration and recurrence interval, in any location of the study area for storm durations from 1 to 24 hours and for recurrence intervals up to 100 years. The reliability of the proposed RDDF equations represents the main concern of the study and it is assessed at two different levels. The first level considers the gauged sites and compares estimates of the design storm obtained with the RDDF equations with at-site estimates based upon the observed annual maximum series of rainfall depth and with design storm estimates resulting from a regional estimator recently developed for the study area through a Hierarchical Regional Approach (HRA) [Gabriele and Arnell, WRR, 27(6), 1991]. The second level performs a reliability assessment of the RDDF equations for ungauged sites by means of a jack-knife procedure. Using the HRA estimator as a reference term, the jack-knife procedure assesses the reliability of design storm estimates provided by the RDDF equations for a given location when dealing with the complete absence of pluviometric information. The results of the analysis show that the proposed RDDF equations represent practical and effective computational means for producing a first guess of the design storm at the available raingauges and reliable design storm estimates for ungauged locations. The first author gratefully acknowledges D.H. Burn for sponsoring the submission of the present abstract.

Spatial characteristics of observed precipitation fields: A catalog of summer storms in Arizona, Volume 2

NASA Technical Reports Server (NTRS)

Fennessey, N. M.; Eagleson, P. S.; Qinliang, W.; Rodriguez-Iturbe, I.

1986-01-01

The parameters of the conceptual model are evaluated from the analysis of eight years of summer rainstorm data from the dense raingage network in the Walnut Gulch catchment near Tucson, Arizona. The occurrence of measurable rain at any one of the 93 gages during a noon to noon day defined a storm. The total rainfall at each of the gages during a storm day constituted the data set for a single storm. The data are interpolated onto a fine grid and analyzed to obtain: an isohyetal plot at 2 mm intervals, the first three moments of point storm depth, the spatial correlation function, the spatial variance function, and the spatial distribution of the total storm depth. The description of the data analysis and the computer programs necessary to read the associated data tapes are presented.

Regionalization of precipitation characteristics in Montana using L-moments

USGS Publications Warehouse

Parrett, C.

1998-01-01

Dimensionless precipitation-frequency curves for estimating precipitation depths having small exceedance probabilities were developed for 2-, 6-, and 24-hour storm durations for three homogeneous regions in Montana. L-moment statistics were used to help define the homogeneous regions. The generalized extreme value distribution was used to construct the frequency curves for each duration within each region. The effective record length for each duration in each region was estimated using a graphical method and was found to range from 500 years for 6-hour duration data in Region 2 to 5,100 years for 24-hour duration data in Region 3. The temporal characteristics of storms were analyzed, and methods for estimating synthetic storm hyetographs were developed. Dimensionless depth-duration data were grouped by independent duration (2,6, and 24 hours) and by region, and the beta distribution was fit to dimensionless depth data for various incremental time intervals. Ordinary least-squares regression was used to develop relations between dimensionless depths for a key, short duration - termed the kernel duration - and dimensionless depths for other durations. The regression relations were used, together with the probabilistic dimensionless depth data for the kernel duration, to calculate dimensionless depth-duration curves for exceedance probabilities from .1 to .9. Dimensionless storm hyetographs for each independent duration in each region were constructed for median value conditions based on an exceedance probability of .5.

Estimating amplitudes of fifth-order sea level fluctuations from peritidal through basinal carbonate deposits, Lower Mississippian, Wyoming-Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elrick, M.; Read, J.F.

1990-05-01

Three types of 1-10-m upward-shallowing cycles are observed in the Lower Mississippian Lodgepole and lower Madison formations of Wyoming and Montana. Typical peritidal cycles have pellet grainstone bases overlain by algal laminites, which are rarely capped by paleosol/regolith horizons. Shallow ramp cycles have burrowed pellet-skeletal wackestone bases overlain by cross-bedded ooid/crinoid grainstone caps. Deep ramp cycles are characterized by sub-wave base limestone/argillite, storm-deposited limestone, overlain by hummocky stratified grainstone caps. Average cycle periods range from 17-155 k.y. This, rhythmically bedded limestone/argillite deposits of basinal facies do not contain shallowing-upward cycles, but do contain 2-4 k.y. limestone/argillite rhythms. These sub-wave basemore » deposit are associated with Waulsortian-type mud mounds which have >50 m synoptic relief. This relief provides minimum water depth estimates for the deposits, and implies storm-wave base was less than 50 m. Two-dimensional computer modeling of cyclic platform through noncyclic basinal deposits allows for bracketing of fifth-order sea level fluctuation amplitudes, thought responsible for cycle formation. Computer models using fifth-order amplitudes less than 20 m do not produce cycles on the deep ramp (assuming a 25-30 m storm-wave base). Amplitudes >30 m produce water depths on the inner ramp that are too deep, and disconformities extend too far into the basin. The absence of meter-scale cycles in the basin suggests water depths were too great to record the effects of sea level oscillations occurring on the platform, or climatic fluctuation, associated with glacio-eustatic sea level oscillations, were not sufficient to affect hemipelagic depositional patterns in the tropical basin environment.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakob, Christian

This report summarises an investigation into the relationship of tropical thunderstorms to the atmospheric conditions they are embedded in. The study is based on the use of radar observations at the Atmospheric Radiation Measurement site in Darwin run under the auspices of the DOE Atmospheric Systems Research program. Linking the larger scales of the atmosphere with the smaller scales of thunderstorms is crucial for the development of the representation of thunderstorms in weather and climate models, which is carried out by a process termed parametrisation. Through the analysis of radar and wind profiler observations the project made several fundamental discoveriesmore » about tropical storms and quantified the relationship of the occurrence and intensity of these storms to the large-scale atmosphere. We were able to show that the rainfall averaged over an area the size of a typical climate model grid-box is largely controlled by the number of storms in the area, and less so by the storm intensity. This allows us to completely rethink the way we represent such storms in climate models. We also found that storms occur in three distinct categories based on their depth and that the transition between these categories is strongly related to the larger scale dynamical features of the atmosphere more so than its thermodynamic state. Finally, we used our observational findings to test and refine a new approach to cumulus parametrisation which relies on the stochastic modelling of the area covered by different convective cloud types.« less

Characteristics of storms driving wave-induced seafloor mobility on the U.S. East Coast continental shelf

USGS Publications Warehouse

Dalyander, P. Soupy; Butman, Bradford

2015-01-01

This study investigates the relationship between spatial and temporal patterns of wave-driven sediment mobility events on the U.S. East Coast continental shelf and the characteristics of the storms responsible for them. Mobility events, defined as seafloor wave stress exceedance of the critical stress of 0.35 mm diameter sand (0.2160 Pa) for 12 or more hours, were identified from surface wave observations at National Data Buoy Center buoys in the Middle Atlantic Bight (MAB) and South Atlantic Bight (SAB) over the period of 1997-2007. In water depths ranging from 36-48 m, there were 4-9 mobility events/year of 1-2 days duration. Integrated wave stress during events (IWAVES) was used as a combined metric of wave-driven mobility intensity and duration. In the MAB, over 67% of IWAVES was caused by extratropical storms, while in the SAB, greater than 66% of IWAVES was caused by tropical storms. On average, mobility events were caused by waves generated by storms located 800+ km away. Far-field hurricanes generated swell 2-4 days before the waves caused mobility on the shelf. Throughout most of the SAB, mobility events were driven by storms to the south, east, and west. In the MAB and near Cape Hatteras, winds from more northerly storms and low-pressure extratropical systems in the mid-western U.S. also drove mobility events. Waves generated by storms off the SAB generated mobility events along the entire U.S. East Coast shelf north to Cape Cod, while Cape Hatteras shielded the SAB area from swell originating to the north offshore of the MAB.

An operation manual for a time-series, storm-activated suspended sediment sampler deployed in the coastal ocean: function, maintenance, and testing procedures

USGS Publications Warehouse

Rendigs, Richard R.; Bothner, Michael H.

2004-01-01

This manual describes the operation and testing procedures for two models of a multi-port suspended sediment sampler that are moored in the coastal ocean and that collect samples on a programmable time schedule that can be interrupted to collect during a storm. The ability to sense and collect samples before, during, and after the height of a storm is a unique feature of these instruments because it provides samples during conditions when it is difficult or impossible to sample from a surface ship. The sensors used to trigger storm sampling are a transmissometer or a pressure sensor. The purpose of such samples is to assess composition and concentration of sediment resuspended from the seafloor during storms and subsequently transported within the coastal system. Both light transmission and the standard deviation of pressure from surface waves correlate with the passage of major storms. The instruments successfully identified the onset of storms and collected samples before, during, and after the storm maximum as programmed. The accuracy of determining suspended matter concentrations collected by the sediment sampler has not been fully evaluated. Preliminary laboratory tests using a suspension of muddy sediment collected in a near-bottom sediment trap yielded excellent results. However in laboratory tests with different sediment types, the suspended matter concentrations determined with these samplers became less accurate with increasing average grain size. Future calibration work is necessary and should be conducted in a facility that ideally has a water depth of at least 30 feet to prevent cavitation of the pump that draws sea water through the filters. The test facility should also have the capability for adding suspended matter of known composition and concentration to a fixed volume of seawater that is well mixed.

Porewater chemistry in a treatment wetland: links to metal retention and release

NASA Astrophysics Data System (ADS)

Vadas, T. M.; Zhang, J.

2011-12-01

Constructed wetlands are gaining increased support for treatment of nonpoint source pollutants. A subsurface flow wetland treating runoff from an agricultural milkhouse floor and roof drainage has been monitored for metal removal. Influent dissolved concentrations from 5 to 30 ppb Cu and 60 to 800 ppb Zn were observed. Effluent concentrations of Zn were always lower from about 3 to 60 ppb Zn, however, Cu was typically around 10 ppb, and much larger at certain points in time, up to 95 ppb Cu. The results were similar in vegetated and non-vegetated wetlands, suggesting abiotic chemistry or microbial activity is controlling metal mobility. Porewater samples were taken using soil moisture lysimeters during both non-storm and storm events to examine metal and related chemistry with depth and distance in the wetland. Under non storm conditions, Cu and Zn average porewater concentrations were 64 and 250 ppb, respectively and did not vary much along the length of the wetland. During a storm event, Zn concentrations in the porewater initially increased near the inlet shortly after a storm, but typically decreased along the length and depth of the wetland to less than 60 ppb. Observed porewater Cu concentrations also increased near the inlet in some cases up to 700 ppb, but dropped rapidly with distance to less than 30 ppb near the middle of the wetland and increased again near the outlet. The dissolved Fe and Mn concentrations follow nearly opposite trends as Cu, increasing and then decreasing along the length of the wetland, suggesting possibly different roles in controlling Cu retention in each stage of the wetland, either co-precipitation with Cu initially, or reductive dissolution and release of Cu in later stages. An understanding of what controls metal retention and release is relevant to optimizing future design parameters of these wetlands.

Wave processes and geologic responses on the floor of the Yellow Sea

USGS Publications Warehouse

Booth, James S.; Winters, William J.

1991-01-01

The floor of the Yellow Sea is a geologically mundane surface: it is nearly horizontal, lacks relief, and, with few exceptions, is devoid of conspicuous geomorphologic features. However, it is the principal repository for the prodigious sediment load of the Huanghe (Yellow River); and, due to its inherent shallowness (average depth is 40 m), it is frequently stressed by waves generated by winter storms and typhoons. Analyses of mass physical properties of cores representing the upper few meters of sediment in the central and north-central Yellow Sea (near the Shandong Peninsula), in conjunction with analyses of slope stability, failure modes, and erodibility, permit an assessment of the likelihood and effect of dynamic, transient geologic events on the seabed.Vane shear-strength profiles along with consolidation test data indicate that the present surface of the seabed is in a depositional mode and is compacting normally. in addition, liquid-limit profiles imply that in the study area these neritic sediments have been accumulating in an environment that probably has not been modified significantly since sea level reached its current level. There is no geotechnical evidence in the nine cores recovered that slope failures have occurred, and clasts, sand lenses or other manifestations of mass movements, including flows, also are absent. These observations support previous interpretations of seismic records. Moreover, slope stability analysis for static conditions shows that the sea floor is quite stable.Regardless, shear-stress levels generated by cyclic loading during major storms may approach the sediment shear strengths, and, when coupled with concomitant excess pore pressures, could cause slope failure. Unless the failed beds collapsed or flowed, however, there probably would be little conspicuous evidence of such a failure. in fact, evaluation of the potential of these sediments for disintegrative behavior suggests that they are not prone to either collapse or flow.Storm waves also generate oscillatory bottom currents that may erode the seabed. Whether the sediment is considered as cohesionless or cohesive, typhoons could have the potential to erode at all water depths within the Yellow Sea (i.e., to 90 m), and winter storms to water depths of 60 m or more. However, in the case of cohesive behavior, it could be that the effect of winter storms and most typhoons is generally less extreme. If the sea floor is repeatedly scoured, it is likely limited to the top few centimeters.Despite the fact that storm waves may cause slope failure and are certainly responsible for frequent scouring, they probably leave only a subtle sedimentologic imprint on the seabed.

Precipitation depth-duration and frequency characteristics for Antelope Valley, Mojave Desert, California

USGS Publications Warehouse

Blodgett, J.C.

1995-01-01

Methods to evaluate changes in the volume of storm runoff from drainage basins that are likely to be urbanized are needed by land-use planning agencies to establish criteria for the design of flood-control systems. To document the changes in runoff volume of basins that may be urbanized, nine small basins that are considered representative of varying hydrologic conditions in Antelope Valley, California, were selected for detailed study. Precipitation and stream-gaging stations were established and data were collected for the period 1990-93. The data collected at these U.S. Geological Survey stations were supplemented by data collected at 35 Long-term precipitation stations operated by the National Oceanic and Atmospheric Administration and the Los Angeles County Department of Public Works. These data will be used to calibrate and verify rainfall-runoff models for the nine basins. Results of the model runs will then be used as a guide for estimating basin runoff characteristics throughout Antelope Valley. Annual precipitation in Antelope Valley ranges from more than 20 inches in the mountains to less than 4 inches on the valley floor. Most precipitation in the valley falls during the months of December through March, but cyclonic storms in the fall and convectional storms in the summer sometimes occur. The duration of most storms ranges from 1 to 8 days, but most of the precipitation usually occurs within the first 2 days. Many parts of the valley have been affected by storms with precipitation depths that equal or exceed 0.60 inch per hour. The storms of January 1943 and March 1983 were the most intense storms of record, with recurrence intervals greater than 100 years in some parts of the valley. Depth-duration ratios were calculated by disaggregating daily total precipitation data for intervals of 1, 2, 3, 4, 6, 12, and 18 hours for storms that occurred during 1990-93. The hourly total precipitation data were then disaggregated at 5-minute intervals. A comparison of the depth-duration data collected during 1990-93 at the Geological Survey stations with the data collected at the other stations indicated that the 1990-93 data are not representative of historical storms. Therefore, depth-duration ratios developed using these data should be considered preliminary for use in disaggregating the historical hourly data for Antelope Valley. Annual maximum 24-hour precipitation records were used to calculate precipitation depth-frequency relations for 23 stations in the valley using the log Pearson type III distribution. These calculations indicate that the storms of January 1943 and March 1983 were the most intense of record in the valley with recurrence intervals greater than 100 years.

Extraordinary flood response of a small urban watershed to short-duration convective rainfall

USGS Publications Warehouse

Smith, J.A.; Miller, A.J.; Baeck, M.L.; Nelson, P.A.; Fisher, G.T.; Meierdiercks, K.L.

2005-01-01

The 9.1 km2 Moores Run watershed in Baltimore, Maryland, experiences floods with unit discharge peaks exceeding 1 m3 s-1 km-2 12 times yr-1, on average. Few, if any, drainage basins in the continental United States have a higher frequency. A thunderstorm system on 13 June 2003 produced the record flood peak (13.2 m3 s-1 km-2) during the 6-yr stream gauging record of Moores Run. In this paper, the hydrometeorology, hydrology, and hydraulics of extreme floods in Moores Run are examined through analyses of the 13 June 2003 storm and flood, as well as other major storm and flood events during the 2000-03 time period. The 13 June 2003 flood, like most floods in Moores Run, was produced by an organized system of thunderstorms. Analyses of the 13 June 2003 storm, which are based on volume scan reflectivity observations from the Sterling, Virginia, WSR-88D radar, are used to characterize the spatial and temporal variability of flash flood producing rainfall. Hydrology of flood response in Moores Run is characterized by highly efficient concentration of runoff through the storm drain network and relatively low runoff ratios. A detailed survey of high-water marks for the 13 June 2003 flood is used, in combination with analyses based on a 2D, depth-averaged open channel flow model (TELEMAC 2D) to examine hydraulics of the 13 June 2003 flood. Hydraulic analyses are used to examine peak discharge estimates for the 13 June flood peak, propagation of flood waves in the Moores Run channel, and 2D flow features associated with channel and floodplain geometry. ?? 2005 American Meteorological Society.

The effect of channel deepening on tides and storm surge: A case study of Wilmington, NC

NASA Astrophysics Data System (ADS)

Familkhalili, R.; Talke, S. A.

2016-09-01

In this study we investigate the hypothesis that increasing channel depth in estuaries can amplify both tides and storm surge by developing an idealized numerical model representing the 1888, 1975, and 2015 bathymetric conditions of the Cape Fear River Estuary, NC. Archival tide gauge data recovered from the U.S. National Archives indicates that mean tidal range in Wilmington has doubled to 1.55 m since the 1880s, with a much smaller increase of 0.07 m observed near the ocean boundary. These tidal changes are reproduced by simulating channel depths of 7 m (1888 condition) and 15.5 m (modern condition). Similarly, model sensitivity studies using idealized, parametric tropical cyclones suggest that the storm surge in the worst-case, CAT-5 event may have increased from 3.8 ± 0.25 m to 5.6 ± 0.6 m since the nineteenth century. The amplification in both tides and storm surge is influenced by reduced hydraulic drag caused by greater mean depths.

Evaluation of nutrient loads from a mountain forest including storm runoff loads.

PubMed

Kunimatsu, T; Otomori, T; Osaka, K; Hamabata, E; Komai, Y

2006-01-01

Water quality and flow rates at a weir installed on the end of Aburahi-S Experimental Watershed (3.34 ha) were measured once a week from 2001 to 2003 and in appropriate intervals from 30 min to 6 h during five storm runoff events caused by each rainfall from 8 mm to 417 mm. The average annual loads of total nitrogen (TN) and total phosphorus (TP) were calculated to be 19.0 and 0.339 kg ha(-1) y(-1) from the periodical data by using the integration interval-loads method (ILM), which did not properly account for storm runoff loads. Three types of L(Q) equations (L = aQ(b)) were derived from correlations between loading rates L and flow rates Q obtained from the periodic observation and from storm runoff observation. L(Q) equation method (LQM), which was derived from the storm runoff observation and allowed for the hysteresis of discharge of materials, gave 9.68 and 0.159 kg ha(-1) y(-1), respectively, by substitution of the sequential hourly data of flow rates. L(R) equation (L = c(R - r)d) was derived from the correlations between the loads and the effective rainfall depth (R - r) measured during the storm runoff events, and L(R) equation method (LRM) calculated 9.83 +/- 1.68 and 0.175 +/- 0.0761 kg ha(-1) y(-1), respectively, by using the rainfall data for the past 16 years. The atmospheric input-fluxes of TN and TP were 16.5 and 0.791 kg ha(-1) y(-1).

Characteristics of aerosol and meteorological parameters during major dust storm events (2005 - 2010) over Beijing, China

NASA Astrophysics Data System (ADS)

Zheng, Sheng; Cao, Chunxiang; Singh, Ramesh

Multi satellite sensors are capable in monitoring dust storm, its path and changes in atmospheric parameters. The present paper discusses aerosol optical properties and meteorological parameters during major dust storm events (2005-2010) over Beijing, China. The back trajectory model shows that the dust is transported from the Inner Mongolia and Mongolia to Beijing. High aerosol optical depth (AOD) and low Ångström exponent (AE) values are observed during dusty days, the average AOD (675 nm) and AE (440-870 nm) during dusty days are 2.33 and 0.06, respectively. The aerosol size distribution (ASD) in coarse mode shows a large increase in the volume during dusty days. The single scattering albedo (SSA) increases with higher wavelength on dusty days, and higher compared to non-dusty days, indicating the presence of high scattering particles due to dust storm events. Characteristics of particles during dusty and non-dusty days are also supported by the real and imaginary parts of refractive index (RI). High air pollution index (API) during dusty days represent poor air quality is a serious health hazard at the time of dust events. The CO volume mixing ratio (COVMR) from Atmospheric Infrared Sounder (AIRS) shows decrease on the ground on dusty days, while the relative humidity (RH) and H _{2}0 mass mixing ratio (H _{2}OMMR) enhance. In addition, due to the dust storm in 2005, enhanced level of water vapor (WV) using Moderate Resolution Imaging Spectroradiometer (MODIS) data is observed in and around Beijing over the dust storms track.

Instantaneous influence of dust storms on the optical scattering property of the ocean: a case study in the Yellow Sea, China.

PubMed

Chen, Shuguo; Zhang, Tinglu; Chen, Wenzhong; Shi, Jinhui; Hu, Lianbo; Song, Qingjun

2016-12-12

Asian dust storms originating from arid or semi-arid regions of China or her adjacent regions have important impact on the atmosphere and water composition, and ecological environment of the Eastern China Seas. This research used data collected in the middle of the South Yellow Sea, China, during a dust storm event from 23 April to 24 April 2006 to analyze the instantaneous influence of dust storms on optical scattering properties, which are closely related to particle characteristics. The analysis results showed that the dust storm had a remarkable influence on the optical scattering property in the upper mixed layer of water, and dust particles drily deposited from the dust storm with an aerosol optical depth of nearly 2.5 into the water could induce a 0.14 m^-1 change in the water optical scattering coefficient at 532 nm at the depth of 4 m. The duration of the instantaneous influence of the dust storm on the water optical scattering properties was short, and this influence disappeared rapidly within approximately 3 hours after the end of the dust storm.

Atlas of depth-duration frequency of precipitation annual maxima for Texas

USGS Publications Warehouse

Asquith, William H.; Roussel, Meghan C.

2004-01-01

The objective of this Texas Department of Transportation (TxDOT) and U.S. Geological Survey (USGS) cooperatively funded project was to develop a simple-to-use atlas of precipitation depths in Texas for selected storm durations and frequencies on the basis of the research results and unpublished digital archives of Asquith (1998). The selected storm durations are 15 and 30 minutes; 1, 2, 3, 6, and 12 hours; and 1, 2, 3, 5, and 7 days. The selected storm frequencies or annual recurrence intervals are 2, 5, 10, 25, 50, 100, 250, and 500 years. Depth-duration frequency (DDF) of annual precipitation maxima is important for cost-effective, risk-mitigated hydrologic design. DDF values are in common and wide-spread use by public and private entities throughout Texas.

Convection index as a tool for trend analysis of intense summer storms in Switzerland

NASA Astrophysics Data System (ADS)

Gaal, Ladislav; Molnar, Peter; Szolgay, Jan

2013-04-01

Convective summer thunderstorms are generally responsible for the most devastating floods in urban and small natural catchments. In this study we focus on the identification of the nature and magnitude of changes in the properties of intense summer storms of convective character in Switzerland in the last three decades. The study is based on precipitation records from the SwissMetNet (MeteoSwiss) network at 63 stations that cover altitudes ranging from 200 up to 3300 m a.s.l. over the period 1981-2012 (32 years). Additionally, the same stations also measure the number of lightning strikes within a range of 30 km from each station. In an accompanying contribution we describe the method how intensive summer storms can be reliably selected out of all storms in long and high resolution precipitation time series. On the basis of the statistical distributions and dependence among key storm characteristics at the event scale (total rainfall depth R, storm duration D, and peak intensity I) and using high resolution lightning data as a surrogate we defined a threshold intensity I* that differentiates between the events accompanied with lightning with an acceptably small probability of misclassification. This allowed us to identify intense summer events with convective character as those where I > I* regardless of their duration or total rainfall depth. The current study makes use of the threshold intensity I* for the definition of a seasonal convection index at each station (Llasat, 2001). This index gives us a measure of 'convectiveness', i.e. the total precipitation depth coming from convective storms relative to the total precipitation depth of all summer storms. We computed the convection index at all 63 stations and analyzed the series for trends. We found that the seasonal convection index increases at most of the stations in Switzerland and in approximately 20% of the cases this increase is statistically significant. This is likely a consequence of the fact that the number of summer storms exceeding the threshold I* also shows an increasing tendency with a similar percentage of statistically significant changes. Although our analysis indicates an increasing tendency in the intensity and frequency of summer storms with convective character in Switzerland, it is not yet clear whether these can be traced to causal factors such as atmospheric warming, etc. This remains an open research question.

Variation of Magnetic Field (By , Bz) Polarity and Statistical Analysis of Solar Wind Parameters during the Magnetic Storm Period

NASA Astrophysics Data System (ADS)

Moon, Ga-Hee

2011-06-01

It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF) component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are divided into three types, which are coronal mass ejection (CME)-driven storms, co-rotating interaction region (CIR)-driven storms, and complicated type storms. Complicated types were not included in this study. For this purpose, the manner in which the direction change of IMF By and Bz components (in geocentric solar magnetospheric coordinate system coordinate) during the main phase is related with the development of the storm is examined. The time-integrated solar wind parameters are compared with the time-integrated disturbance storm time (Dst) index during the main phase of each magnetic storm. The time lag with the storm size is also investigated. Some results are worth noting: CME-driven storms, under steady conditions of Bz < 0, represent more than half of the storms in number. That is, it is found that the average number of storms for negative sign of IMF Bz (T1~T4) is high, at 56.4%, 53.0%, and 63.7% in each storm category, respectively. However, for the CIR-driven storms, the percentage of moderate storms is only 29.2%, while the number of intense storms is more than half (60.0%) under the Bz < 0 condition. It is found that the correlation is highest between the time-integrated IMF Bz and the time-integrated Dst index for the CME-driven storms. On the other hand, for the CIR-driven storms, a high correlation is found, with the correlation coefficient being 0.93, between time-integrated Dst index and time-integrated solar wind speed, while a low correlation, 0.51, is found between timeintegrated Bz and time-integrated Dst index. The relationship between storm size and time lag in terms of hours from Bz minimum to Dst minimum values is investigated. For the CME-driven storms, time lag of 26% of moderate storms is one hour, whereas time lag of 33% of moderate storms is two hours for the CIR-driven storms. The average values of solar wind parameters for the CME and CIR-driven storms are also examined. The average values of |Dstmin| and |Bzmin| for the CME-driven storms are higher than those of CIR-driven storms, while the average value of temperature is lower.

Defining Coastal Storm and Quantifying Storms Applying Coastal Storm Impulse Parameter

NASA Astrophysics Data System (ADS)

Mahmoudpour, Nader

2014-05-01

What defines a storm condition and what would initiate a "storm" has not been uniquely defined among scientists and engineers. Parameters that have been used to define a storm condition can be mentioned as wind speed, beach erosion and storm hydrodynamics parameters such as wave height and water levels. Some of the parameters are storm consequential such as beach erosion and some are not directly related to the storm hydrodynamics such as wind speed. For the purpose of the presentation, the different storm conditions based on wave height, water levels, wind speed and beach erosion will be discussed and assessed. However, it sounds more scientifically to have the storm definition based on the hydrodynamic parameters such as wave height, water level and storm duration. Once the storm condition is defined and storm has initiated, the severity of the storm would be a question to forecast and evaluate the hazard and analyze the risk in order to determine the appropriate responses. The correlation of storm damages to the meteorological and hydrodynamics parameters can be defined as a storm scale, storm index or storm parameter and it is needed to simplify the complexity of variation involved developing the scale for risk analysis and response management. A newly introduced Coastal Storm Impulse (COSI) parameter quantifies storms into one number for a specific location and storm event. The COSI parameter is based on the conservation of linear, horizontal momentum to combine storm surge, wave dynamics, and currents over the storm duration. The COSI parameter applies the principle of conservation of momentum to physically combine the hydrodynamic variables per unit width of shoreline. This total momentum is then integrated over the duration of the storm to determine the storm's impulse to the coast. The COSI parameter employs the mean, time-averaged nonlinear (Fourier) wave momentum flux, over the wave period added to the horizontal storm surge momentum above the Mean High Water (MHW) integrated over the storm duration. The COSI parameter methodology has been applied to a 10-year data set from 1994 to 2003 at US Army Corps of Engineers, Field Research Facility (FRF) located on the Atlantic Ocean in Duck, North Carolina. The storm duration was taken as the length of time (hours) that the spectral significant wave heights were equal or greater than 1.6 meters for at least a 12 hour, continuous period. Wave heights were measured in 8 meters water depth and water levels measured at the NOAA/NOS tide gauge at the end of the FRF pier. The 10-year data set were analyzed applying the aforementioned storm criteria and produced 148 coastal events including Hurricanes and Northeasters. The results of this analysis and application of the COSI parameter to determine "Extra Ordinary" storms in Federal Projects for the Gulf of Mexico, 2012 hurricane season will be discussed at the time of presentation.

Performance of shrub willows (Salix spp.) as an evapotranspiration cover on Solvay wastebeds

NASA Astrophysics Data System (ADS)

Mirck, Jaconette

2009-12-01

Soda ash (Na2CO3) production in the Syracuse New York area created 607 ha of wastebeds over the course of about 100 years. Today the primary concern of the Solvay wastebeds is high chloride concentrations in the leachate and storm water that may end up in the groundwater and nearby Onondaga Lake. The potential of shrub willow evapotranspiration (ET) covers to minimize leaching and to manage storm water was assessed in two studies. A sap flow sensor field study to estimate transpiration rates of four shrub willow varieties over an entire growing season. A greenhouse study focused on recycling saline Solvay storm water onto shrub willows. Annual sap flow and crop coefficients (Kc) were similar among four shrub willows, but differences were present over the course of the growing season. Peak K c values did not coincide with peak leaf area index (LAI), as might be expected if LAI were the main driver of transpiration. Rather than solely being driven by LAI, coupling with the atmosphere was an important factor in stand level sap flow. Estimates of ET were measured during both experiments, the ET/sap flow rankings of the shrub willow varieties were similar; Salix miyabeana (SX64)< S. purpurea (9882-34)< S. miyabeana x S. sachalinensis (9870-23 or 9870-40). In the greenhouse study, Solvay storm water that contained 1,625 mg Cl - L-1 (close to the average storm water concentration) did not significantly decrease ET values or growth for any of the willow varieties. Mass balances of sodium and chloride were carried out to assess the potentials of recycling saline Solvay storm water back onto a shrub willow ET cover during the growing season. During a ten-week study the combination of a shallow depth soil (33 cm) and a high irrigation regime (170% of average precipitation in the Syracuse NY area) resulted in the accumulation of at least 62% of both sodium and chloride in the plant/soil system for all five Solvay storm water treatments. Both studies indicated that shrub willows have the characteristics to be part of a sustainable ET cover on the Solvay wastebeds, which will decrease leaching of sodium and chloride. Key words. Coupling/decoupling, crop coefficient, hydraulic control, leaf area index, mass balance, phytoremediation, sap flow.

Modeling storms improves estimates of long-term shoreline change

NASA Astrophysics Data System (ADS)

Frazer, L. Neil; Anderson, Tiffany R.; Fletcher, Charles H.

2009-10-01

Large storms make it difficult to extract the long-term trend of erosion or accretion from shoreline position data. Here we make storms part of the shoreline change model by means of a storm function. The data determine storm amplitudes and the rate at which the shoreline recovers from storms. Historical shoreline data are temporally sparse, and inclusion of all storms in one model over-fits the data, but a probability-weighted average model shows effects from all storms, illustrating how model averaging incorporates information from good models that might otherwise have been discarded as un-parsimonious. Data from Cotton Patch Hill, DE, yield a long-term shoreline loss rate of 0.49 ± 0.01 m/yr, about 16% less than published estimates. A minimum loss rate of 0.34 ± 0.01 m/yr is given by a model containing the 1929, 1962 and 1992 storms.

Spatial variability in the trends in extreme storm surges and weekly-scale high water levels in the eastern Baltic Sea

NASA Astrophysics Data System (ADS)

Soomere, Tarmo; Pindsoo, Katri

2016-03-01

We address the possibilities of a separation of the overall increasing trend in maximum water levels of semi-enclosed water bodies into associated trends in the heights of local storm surges and basin-scale components of the water level based on recorded and modelled local water level time series. The test area is the Baltic Sea. Sequences of strong storms may substantially increase its water volume and raise the average sea level by almost 1 m for a few weeks. Such events are singled out from the water level time series using a weekly-scale average. The trends in the annual maxima of the weekly average have an almost constant value along the entire eastern Baltic Sea coast for averaging intervals longer than 4 days. Their slopes are ~4 cm/decade for 8-day running average and decrease with an increase of the averaging interval. The trends for maxima of local storm surge heights represent almost the entire spatial variability in the water level maxima. Their slopes vary from almost zero for the open Baltic Proper coast up to 5-7 cm/decade in the eastern Gulf of Finland and Gulf of Riga. This pattern suggests that an increase in wind speed in strong storms is unlikely in this area but storm duration may have increased and wind direction may have rotated.

Development of the Fully Adaptive Storm Tide (FAST) Model for hurricane induced storm surges and associated inundation

NASA Astrophysics Data System (ADS)

Teng, Y. C.; Kelly, D.; Li, Y.; Zhang, K.

2016-02-01

A new state-of-the-art model (the Fully Adaptive Storm Tide model, FAST) for the prediction of storm surges over complex landscapes is presented. The FAST model is based on the conservation form of the full non-linear depth-averaged long wave equations. The equations are solved via an explicit finite volume scheme with interfacial fluxes being computed via Osher's approximate Riemann solver. Geometric source terms are treated in a high order manner that is well-balanced. The numerical solution technique has been chosen to enable the accurate simulation of wetting and drying over complex topography. Another important feature of the FAST model is the use of a simple underlying Cartesian mesh with tree-based static and dynamic adaptive mesh refinement (AMR). This permits the simulation of unsteady flows over varying landscapes (including localized features such as canals) by locally increasing (or relaxing) grid resolution in a dynamic fashion. The use of (dynamic) AMR lowers the computational cost of the storm surge model whilst retaining high resolution (and thus accuracy) where and when it is required. In additional, the FAST model has been designed to execute in a parallel computational environment with localized time-stepping. The FAST model has already been carefully verified against a series of benchmark type problems (Kelly et al. 2015). Here we present two simulations of the storm tide due to Hurricane Ike(2008) and Hurricane Sandy (2012). The model incorporates high resolution LIDAR data for the major portion of the New York City. Results compare favorably with water elevations measured by NOAA tidal gauges, by mobile sensors deployed and high water marks collected by the USGS.

Comparison of sediment grain size characteristics on nourished and un-nourished estuarine beaches and impacts on horseshoe crab habitat, Delaware Bay, New Jersey

USGS Publications Warehouse

Jackson, N.L.; Smith, D.R.; Nordstrom, K.F.

2005-01-01

This study was undertaken to determine whether nourished and un-nourished estuarine beaches have conspicuous differences in sediment size and sorting that could affect their value as habitat for horseshoe crabs. Comparisons are made of beach profiles and sediment samples gathered at 0.15 m and 0.30 m depths on the backshore, at spring tide elevation, neap tide elevation, and the lower foreshore on 5 un-nourished and 3 nourished beaches in Delaware Bay, where tidal range is <2.0 m. The backshore is at least 0.5 m higher on the recently nourished beaches than on a nearby un-nourished beach reworked by storm waves. Nourishing these beaches to elevations higher than natural overwash heights will restrict natural evolution of the upper beach. Sediments at spring tide elevation on un-nourished sites average 0.72 mm in diameter at 0.15 m depth and 0.67 mm at 0.30 m depth.The similarity in size implies a relatively deep active layer in the zone of maximum cut and fill associated with cyclic profile change during low frequency, high magnitude storms. Sedimentary changes at neap tide elevation may be influenced more by depth of activation by waves than by cycles of deposition and erosion. Sediment at 0.15 m depth at spring and neap locations on the foreshore of nourished beaches is finer (0.51 mm) and better sorted (0.82 phi) than at 0.30 m depth (0.91 mm, 1.38 phi), implying that waves have not reworked the deeper sediments. Differences in sediment characteristics at depth may persist on eroding nourished beaches, where unreworked fill is close to the surface. Sediment texture influences horseshoe crab egg viability and development. Lower rates of water movement through the foreshore and greater thickness of the capillary fringe on nourished sites suggests that greater moisture retention will occur where horseshoe crabs bury eggs and may provide more favorable conditions for egg development, but the depth of these conditions will not be great on a recently nourished beach. ?? 2005 Gebru??der Borntraeger.

Convective rain rates and their evolution during storms in a semiarid climate

NASA Technical Reports Server (NTRS)

Doneaud, A. A.; Miller, J. R., Jr.; Ionescu-Niscov, S.

1984-01-01

The semiarid climate of the U.S. northern High Plains region has been studied with respect to rain rates and their evolution during summertime convective storms, using radar data from a total of 750 radar echo clusters. Analysis of this data suggests that the average rain rate R among storms is in a first approximation independent of the total rain volume, if the entire storm duration is considered in the averaging process. R primarily depends on the reflectivity threshold considered in calculating the area coverage integrated over the lifetime of the storm. R evolution during storms is analyzed by dividing each storm lifetime into 10 min, 1, 2, and 4 hours, as well as growing and decaying periods. The value of R remained independent of the total rain volume when the growing or decaying periods of storms were considered separately.

Application of Radar-Rainfall Estimates to Probable Maximum Precipitation in the Carolinas

NASA Astrophysics Data System (ADS)

England, J. F.; Caldwell, R. J.; Sankovich, V.

2011-12-01

Extreme storm rainfall data are essential in the assessment of potential impacts on design precipitation amounts, which are used in flood design criteria for dams and nuclear power plants. Probable Maximum Precipitation (PMP) from National Weather Service Hydrometeorological Report 51 (HMR51) is currently used for design rainfall estimates in the eastern U.S. The extreme storm database associated with the report has not been updated since the early 1970s. In the past several decades, several extreme precipitation events have occurred that have the potential to alter the PMP values, particularly across the Southeast United States (e.g., Hurricane Floyd 1999). Unfortunately, these and other large precipitation-producing storms have not been analyzed with the detail required for application in design studies. This study focuses on warm-season tropical cyclones (TCs) in the Carolinas, as these systems are the critical maximum rainfall mechanisms in the region. The goal is to discern if recent tropical events may have reached or exceeded current PMP values. We have analyzed 10 storms using modern datasets and methodologies that provide enhanced spatial and temporal resolution relative to point measurements used in past studies. Specifically, hourly multisensor precipitation reanalysis (MPR) data are used to estimate storm total precipitation accumulations at various durations throughout each storm event. The accumulated grids serve as input to depth-area-duration calculations. Individual storms are then maximized using back-trajectories to determine source regions for moisture. The development of open source software has made this process time and resource efficient. Based on the current methodology, two of the ten storms analyzed have the potential to challenge HMR51 PMP values. Maximized depth-area curves for Hurricane Floyd indicate exceedance at 24- and 72-hour durations for large area sizes, while Hurricane Fran (1996) appears to exceed PMP at large area sizes for short-duration, 6-hour storms. Utilizing new methods and data, however, requires careful consideration of the potential limitations and caveats associated with the analysis and further evaluation of the newer storms within the context of historical storms from HMR51. Here, we provide a brief background on extreme rainfall in the Carolinas, along with an overview of the methods employed for converting MPR to depth-area relationships. Discussion of the issues and limitations, evaluation of the various techniques, and comparison to HMR51 storms and PMP values are also presented.

Storm surges and coastal impacts at Mar del Plata, Argentina

NASA Astrophysics Data System (ADS)

Fiore, Mónica M. E.; D'Onofrio, Enrique E.; Pousa, Jorge L.; Schnack, Enrique J.; Bértola, Germán R.

2009-07-01

Positive storm surges (PSS) lasting for several days can raise the water level producing significant differences between the observed level and the astronomical tide. These storm events can be more severe if they coincide with a high tide or if they bracket several tidal cycles, particularly in the case of the highest astronomical tide. Besides, the abnormal sea-level elevation near the coast can cause the highest waves generated to attack the upper beach. This combination of factors can produce severe erosion, threatening sectors located along the coastline. These effects would be more serious if the storm surge height and duration increase as a result of a climatic change. The Mar del Plata (Argentina) coastline and adjacent areas are exposed to such effects. A statistical characterization of PSS based on their intensity, duration and frequency, including a surge event classification, was performed utilizing tide-gauge records over the period 1956-2005. A storm erosion potential index (SEPI) was calculated from observed levels based on hourly water level measurements. The index was related to beach profile responses to storm events. Also, a return period for extreme SEPI values was calculated. Results show an increase in the average number of positive storm surge events per decade. Considering all the events, the last decade (1996-2005) exhibits an average 7% increase compared to each one of the previous decades. A similar behavior was found for the decadal average of the heights of maximum annual positive storm surges. In this case the average height of the last two decades exceeds that of the previous decades by approximately 8 cm. The decadal average of maximum annual duration of these meteorological events shows an increase of 2 h in the last three decades. A possible explanation of the changes in frequency, height and duration of positive storm surges at Mar del Plata would seem to lie in the relative mean sea-level rise.

Discontinuous Galerkin methods for modeling Hurricane storm surge

NASA Astrophysics Data System (ADS)

Dawson, Clint; Kubatko, Ethan J.; Westerink, Joannes J.; Trahan, Corey; Mirabito, Christopher; Michoski, Craig; Panda, Nishant

2011-09-01

Storm surge due to hurricanes and tropical storms can result in significant loss of life, property damage, and long-term damage to coastal ecosystems and landscapes. Computer modeling of storm surge can be used for two primary purposes: forecasting of surge as storms approach land for emergency planning and evacuation of coastal populations, and hindcasting of storms for determining risk, development of mitigation strategies, coastal restoration and sustainability. Storm surge is modeled using the shallow water equations, coupled with wind forcing and in some events, models of wave energy. In this paper, we will describe a depth-averaged (2D) model of circulation in spherical coordinates. Tides, riverine forcing, atmospheric pressure, bottom friction, the Coriolis effect and wind stress are all important for characterizing the inundation due to surge. The problem is inherently multi-scale, both in space and time. To model these problems accurately requires significant investments in acquiring high-fidelity input (bathymetry, bottom friction characteristics, land cover data, river flow rates, levees, raised roads and railways, etc.), accurate discretization of the computational domain using unstructured finite element meshes, and numerical methods capable of capturing highly advective flows, wetting and drying, and multi-scale features of the solution. The discontinuous Galerkin (DG) method appears to allow for many of the features necessary to accurately capture storm surge physics. The DG method was developed for modeling shocks and advection-dominated flows on unstructured finite element meshes. It easily allows for adaptivity in both mesh ( h) and polynomial order ( p) for capturing multi-scale spatial events. Mass conservative wetting and drying algorithms can be formulated within the DG method. In this paper, we will describe the application of the DG method to hurricane storm surge. We discuss the general formulation, and new features which have been added to the model to better capture surge in complex coastal environments. These features include modifications to the method to handle spherical coordinates and maintain still flows, improvements in the stability post-processing (i.e. slope-limiting), and the modeling of internal barriers for capturing overtopping of levees and other structures. We will focus on applications of the model to recent events in the Gulf of Mexico, including Hurricane Ike.

THEMIS Observations of Mars Aerosol Optical Depth from 2002-2008

NASA Technical Reports Server (NTRS)

Smith, Michael D.

2009-01-01

We use infrared images obtained by the Thermal Emission Imaging System (THEMIS) instrument on-board Mars Odyssey to retrieve the optical depth of dust and water ice aerosols over more than 3.5 martian years between February 2002 (MY 25, Ls=330 ) and December 2008 (MY 29, Ls=183). These data provide an important bridge between earlier TES observations and recent observations from Mars Express and Mars Reconnaissance Orbiter. An improvement to our earlier retrieval to include atmospheric temperature information from THEMIS Band 10 observations leads to much improved retrievals during the largest dust storms. The new retrievals show moderate dust storm activity during Mars Years 26 and 27, although details of the strength and timing of dust storms is different from year to year. A planet-encircling dust storm event was observed during Mars Year 28 near Southern Hemisphere Summer solstice. A belt of low-latitude water ice clouds was observed during the aphelion season during each year, Mars Years 26 through 29. The optical depth of water ice clouds is somewhat higher in the THEMIS retrievals at approximately 5:00 PM local time than in the TES retrievals at approximately 2:00 PM, suggestive of possible local time variation of clouds.

Storm-induced water dynamics and thermohaline structure at the tidewater Flade Isblink Glacier outlet to the Wandel Sea (NE Greenland)

NASA Astrophysics Data System (ADS)

Kirillov, Sergei; Dmitrenko, Igor; Rysgaard, Søren; Babb, David; Toudal Pedersen, Leif; Ehn, Jens; Bendtsen, Jørgen; Barber, David

2017-11-01

In April 2015, an ice-tethered conductivity-temperature-depth (CTD) profiler and a down-looking acoustic Doppler current profiler (ADCP) were deployed from the landfast ice near the tidewater glacier terminus of the Flade Isblink Glacier in the Wandel Sea, NE Greenland. The 3-week time series showed that water dynamics and the thermohaline structure were modified considerably during a storm event on 22-24 April, when northerly winds exceeded 15 m s-1. The storm initiated downwelling-like water dynamics characterized by on-shore water transport in the surface (0-40 m) layer and compensating offshore flow at intermediate depths. After the storm, currents reversed in both layers, and the relaxation phase of downwelling lasted ˜ 4 days. Although current velocities did not exceed 5 cm s-1, the enhanced circulation during the storm caused cold turbid intrusions at 75-95 m depth, which are likely attributable to subglacial water from the Flade Isblink Ice Cap. It was also found that the semidiurnal periodicities in the temperature and salinity time series were associated with the lunar semidiurnal tidal flow. The vertical structure of tidal currents corresponded to the first baroclinic mode of the internal tide with a velocity minimum at ˜ 40 m. The tidal ellipses rotate in opposite directions above and below this depth and cause a divergence of tidal flow, which was observed to induce semidiurnal internal waves of about 3 m height at the front of the glacier terminus. Our findings provide evidence that shelf-basin interaction and tidal forcing can potentially modify coastal Wandel Sea waters even though they are isolated from the atmosphere by landfast sea ice almost year-round. The northerly storms over the continental slope cause an enhanced circulation facilitating a release of cold and turbid subglacial water to the shelf. The tidal flow may contribute to the removal of such water from the glacial terminus.

Predictions and Observations of Munitions Burial Under Intense Storm Waves at Duck, NC

NASA Astrophysics Data System (ADS)

Calantoni, J.; Klammer, H.; Sheremet, A.

2017-12-01

The fate of munitions or unexploded ordnance (UXO) resting on a submarine sediment bed is a critical safety concern. Munitions may remain in place or completely disappear for significant but unknown periods, after becoming buried in the sediment bed. Clearly, burial of munitions drastically complicates the detection and removal of potential threats. Here, we present field data of wave height and surrogate munitions burial depths near the 8-m isobath at the U.S. Army Corps of Engineers, Field Research Facility, Duck, North Carolina, observed between January and March 2015. The experiment captured a remarkable sequence of storms that included at least 10 events, of which 6 were characterized by wave fields of significant heights exceeding 2 m and with peak periods of approximately 10 s. During the strongest storm, waves of 14 s period and heights exceeding 2 m were recorded for more than 3 days; significant wave height reached 5 m at the peak of activity. At the end of the experiment, divers measured munition burial depths of up to 60 cm below the seabed level. However, the local bathymetry showed less than 5 cm variation between the before and after-storm states, suggesting the local net sediment accumulation / loss was negligible. The lack of bathymetric variability strongly suggests that the munitions sank into the bed, which would suggest an extreme state of sand agitation during the storm. We explore existing analytical solutions for the dynamic interaction between waves and sediment to predict munitions burial depths. Measured time series of wave pressure near the sediment bed were converted into wave-induced changes in pore pressures and the effective stress states of the sediment. Different sediment failure criteria based on minimum normal and maximum shear stresses were then applied to evaluate the appropriateness of individual failure criteria to predict observed burial depths. Results are subjected to a sensitivity analysis with respect to uncertain sediment parameters and summarized by representing cumulative failure times as a function of depth.

Surface Wind Field Analyses of Tropical Cyclones in the Western Pacific

DTIC Science & Technology

2012-09-01

Averaged vertical profiles of actual wind speeds (m s-1) from all dropwindsondes in three ITOP storms . (b) Averaged vertical profiles of wind speeds...for the entire set of winds from the three ITOP 2010 typhoons. .............................1  Figure 27.  a) Storm -relative motion flight track for...1  Figure 28.  a) Storm -relative motion flight track for flight 0420 in TY Fanapi

Reversing storm hotspots on sandy beaches: Spatial and temporal characteristics

USGS Publications Warehouse

List, J.H.; Farris, A.S.; Sullivan, C.

2006-01-01

Coastal erosion hotspots are defined as sections of coast that exhibit significantly higher rates of erosion than adjacent areas. This paper describes the spatial and temporal characteristics of a recently identified type of coastal erosion hotspot, which forms in response to storms on uninterrupted sandy coasts largely free from human intervention. These are referred to here as reversing storm hotspots because the erosion is reversed by accretion of a similar magnitude to the storm-induced erosion. The accretion occurs within a few days or weeks of fair weather after the storm. Reversing storm hotspots observed here, on two US east coast beaches, have a longshore length averaging 3.86 km, a cross-shore excursion (magnitude of erosion or accretion) averaging 15.4 m, and a time scale of days to weeks associated with individual storm events. These spatial and temporal scales clearly distinguish reversing storm hotspots from previously described forms of longshore variability in erosion, including those attributed to several types of shoreline undulations and hotspots associated with long-term shoreline change. 

Prediction and observation of munitions burial in energetic storms

NASA Astrophysics Data System (ADS)

Klammler, Harald; Sheremet, Alexandru; Calantoni, Joseph

2017-04-01

The fate of munitions or unexploded ordnance (UXO) resting on a submarine sediment bed is a critical safety concern. Munitions may be transported in uncontrolled ways to create potentially dangerous situations at places like beaches or ports. Alternatively, they may remain in place or completely disappear for significant but unknown periods, after becoming buried in the sediment bed. Clearly, burial of munitions drastically complicates the detection and removal of potential threats. Here, we present field data of wave height and (surrogate) munitions burial depths near the 8-m isobath at the U.S. Army Corps of Engineers, Field Research Facility, Duck, North Carolina, observed between January and March 2015. The experiment captured a remarkable sequence of storms that included at least 10 events, of which 6 were characterized by wave fields of significant heights exceeding 2 m and with peak periods of approximately 10 s. During the strongest storm, waves of 14 s period and heights exceeding 2 m were recorded for more than 3 days; significant wave height reached 5 m at the peak of activity. At the end of the experiment, divers measured munition burial depths of up to 60 cm below the seabed level. However, the local bathymetry showed less than 5 cm variation between the before and after-storm states, suggesting the local net sediment accumulation / loss was negligible. The lack of bathymetric variability excludes the possibility of burial by a migrating bed form or by sediment deposition, and strongly indicates that the munitions sank into the bed. The depth of burial also suggest an extreme state of sand agitation during the storm. For predicting munitions burial depths, we explore existing analytical solutions for the dynamic interaction between waves and sediment. Measured time series of wave pressure near the sediment bed were converted into wave-induced changes in pore pressures and the effective stress states of the sediment. Different sediment failure criteria based on minimum normal and maximum shear stresses are then applied to evaluate the appropriateness of individual failure criteria to predict observed burial depths. Results are subjected to a sensitivity analysis with respect to uncertain sediment parameters and summarized by representing cumulative failure times as a function of depth.

Rain fall data for the design of sewer pipe systems

NASA Astrophysics Data System (ADS)

Arnell, V.

1982-03-01

A comparison of designs of sewer pipes for different types of rainfall data is presented. Local coefficients were evaluated from an 18-year historical rainfall record for the following design storms: The Average-Intensity-Duration Design Storm, The Chicago Design Storm, The Sifalda Design Storm, The Illinois State Water Survey Design Storm, and The Flood Studies Report Design Storm. Historical rainfalls as well as the above design storms were used for the calculations of peak-flow values.

Trends in the components of extreme water levels signal a rotation of winds in strong storms in the eastern Baltic Sea

NASA Astrophysics Data System (ADS)

Pindsoo, Katri; Soomere, Tarmo

2016-04-01

The water level time series and particularly temporal variations in water level extremes usually do not follow any simple rule. Still, the analysis of linear trends in extreme values of surge levels is a convenient tool to obtain a first approximation of the future projections of the risks associated with coastal floodings. We demonstrate how this tool can be used to extract essential information about concealed changes in the forcing factors of seas and oceans. A specific feature of the Baltic Sea is that sequences of even moderate storms may raise the average sea level by almost 1 m for a few weeks. Such events occur once in a few years. They substantially contribute to the extreme water levels in the eastern Baltic Sea: the most devastating coastal floodings occur when a strong storm from unfortunate direction arrives during such an event. We focus on the separation of subtidal (weekly-scale) processes from those which are caused by a single storm and on establishing how much these two kinds of events have contributed to the increase in the extreme water levels in the eastern Baltic Sea. The analysis relies on numerically reconstructed sea levels produced by the RCO (Rossby Center, Swedish Meteorological and Hydrological Institute) ocean model for 1961-2005. The reaction of sea surface to single storm events is isolated from the local water level time series using a running average over a fixed interval. The distribution of average water levels has an almost Gaussian shape for averaging lengths from a few days to a few months. The residual (total water level minus the average) can be interpreted as a proxy of the local storm surges. Interestingly, for the 8-day average this residual almost exactly follows the exponential distribution. Therefore, for this averaging length the heights of local storm surges reflect an underlying Poisson process. This feature is universal for the entire eastern Baltic Sea coast. The slopes of the exponential distribution for low and high water levels are different, vary markedly along the coast and provide a useful quantification of the vulnerability of single coastal segments with respect to coastal flooding. The formal linear trends in the extreme values of these water level components exhibit radically different spatial variations. The slopes of the trends in the weekly average are almost constant (~4 cm/decade for 8-day running average) along the entire eastern Baltic Sea coast. This first of all indicates that the duration of storm sequences has increased. The trends for maxima of local storm surge heights represent almost the entire spatial variability in the water level extremes. Their slopes are almost zero at the open Baltic Proper coasts of the Western Estonian archipelago. Therefore, an increase in wind speed in strong storms is unlikely in this area. In contrast, the slopes in question reach 5-7 cm/decade in the eastern Gulf of Finland and Gulf of Riga. This feature suggests that wind direction in strongest storms may have rotated in the northern Baltic Sea.

76 FR 66891 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-28

... Respondents: 265. Average Hours per Response: StormReady, Tsunami-Ready and StormReady/TsunamiReady... request is for revision of a current information collection. The StormReady, TsunamiReady and and StormReady/TsunamiReady Programs are voluntary programs offered to provide guidance and incentive to...

Modeling Costal Zone Responses to Sea-Level Rise Using MoCCS: A Model of Complex Coastal System

NASA Astrophysics Data System (ADS)

Dai, H.; Niedoroda, A. W.; Ye, M.; Saha, B.; Donoghue, J. F.; Kish, S.

2011-12-01

Large-scale coastal systems consisting of several morphological components (e.g. beach, surf zone, dune, inlet, shoreface, and estuary) can be expected to exhibit complex and interacting responses to changes in the rate of sea level rise and storm climate. We have developed a numerical model of complex coastal systems (MoCCS), derived from earlier morphdynamic models, to represent the large-scale time-averaged physical processes that shape each component and govern the component interactions. These control the ongoing evolution of the barrier islands, beach and dune erosion, shoal formation and sand withdrawal at tidal inlets, depth changes in the bay, and changes in storm flooding. The model has been used to study the response of an idealized coastal system with physical characteristics and storm climatology similar to Santa Rosa Island on the Florida Panhandle coast. Five SLR scenarios have been used, covering the range of recently published projections for the next century. Each scenario has been input with a constant and then a time-varying storm climate. The results indicate that substantial increases in the rate of beach erosion are largely due to increased sand transfer to inlet shoals with increased rates of sea level rise. The barrier island undergoes cycles of dune destruction and regrowth, leading to sand deposition. This largely maintains island freeboard but is progressively less effective in offsetting bayside inundation and marsh habitat loss at accelerated sea level rise rates.

Distributed watershed modeling of design storms to identify nonpoint source loading areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Endreny, T.A.; Wood, E.F.

1999-03-01

Watershed areas that generate nonpoint source (NPS) polluted runoff need to be identified prior to the design of basin-wide water quality projects. Current watershed-scale NPS models lack a variable source area (VSA) hydrology routine, and are therefore unable to identify spatially dynamic runoff zones. The TOPLATS model used a watertable-driven VSA hydrology routine to identify runoff zones in a 17.5 km{sup 2} agricultural watershed in central Oklahoma. Runoff areas were identified in a static modeling framework as a function of prestorm watertable depth and also in a dynamic modeling framework by simulating basin response to 2, 10, and 25 yrmore » return period 6 h design storms. Variable source area expansion occurred throughout the duration of each 6 h storm and total runoff area increased with design storm intensity. Basin-average runoff rates of 1 mm h{sup {minus}1} provided little insight into runoff extremes while the spatially distributed analysis identified saturation excess zones with runoff rates equaling effective precipitation. The intersection of agricultural landcover areas with these saturation excess runoff zones targeted the priority potential NPS runoff zones that should be validated with field visits. These intersected areas, labeled as potential NPS runoff zones, were mapped within the watershed to demonstrate spatial analysis options available in TOPLATS for managing complex distributions of watershed runoff. TOPLATS concepts in spatial saturation excess runoff modelling should be incorporated into NPS management models.« less

The influence of bed friction variability due to land cover on storm-driven barrier island morphodynamics

USGS Publications Warehouse

Passeri, Davina L.; Long, Joseph W.; Plant, Nathaniel G.; Bilskie, Matthew V.; Hagen, Scott C.

2018-01-01

Variations in bed friction due to land cover type have the potential to influence morphologic change during storm events; the importance of these variations can be studied through numerical simulation and experimentation at locations with sufficient observational data to initialize realistic scenarios, evaluate model accuracy and guide interpretations. Two-dimensional in the horizontal plane (2DH) morphodynamic (XBeach) simulations were conducted to assess morphodynamic sensitivity to spatially varying bed friction at Dauphin Island, AL using hurricanes Ivan (2004) and Katrina (2005) as experimental test cases. For each storm, three bed friction scenarios were simulated: (1) a constant Chezy coefficient across land and water, (2) a constant Chezy coefficient across land and depth-dependent Chezy coefficients across water, and (3) spatially varying Chezy coefficients across land based on land use/land cover (LULC) data and depth-dependent Chezy coefficients across water. Modeled post-storm bed elevations were compared qualitatively and quantitatively with post-storm lidar data. Results showed that implementing spatially varying bed friction influenced the ability of XBeach to accurately simulate morphologic change during both storms. Accounting for frictional effects due to large-scale variations in vegetation and development reduced cross-barrier sediment transport and captured overwash and breaching more accurately. Model output from the spatially varying friction scenarios was used to examine the need for an existing sediment transport limiter, the influence of pre-storm topography and the effects of water level gradients on storm-driven morphodynamics.

Catastrophe loss modelling of storm-surge flood risk in eastern England.

PubMed

Muir Wood, Robert; Drayton, Michael; Berger, Agnete; Burgess, Paul; Wright, Tom

2005-06-15

Probabilistic catastrophe loss modelling techniques, comprising a large stochastic set of potential storm-surge flood events, each assigned an annual rate of occurrence, have been employed for quantifying risk in the coastal flood plain of eastern England. Based on the tracks of the causative extratropical cyclones, historical storm-surge events are categorized into three classes, with distinct windfields and surge geographies. Extreme combinations of "tide with surge" are then generated for an extreme value distribution developed for each class. Fragility curves are used to determine the probability and magnitude of breaching relative to water levels and wave action for each section of sea defence. Based on the time-history of water levels in the surge, and the simulated configuration of breaching, flow is time-stepped through the defences and propagated into the flood plain using a 50 m horizontal-resolution digital elevation model. Based on the values and locations of the building stock in the flood plain, losses are calculated using vulnerability functions linking flood depth and flood velocity to measures of property loss. The outputs from this model for a UK insurance industry portfolio include "loss exceedence probabilities" as well as "average annualized losses", which can be employed for calculating coastal flood risk premiums in each postcode.

Forecasting Dust Storms Using the CARMA-Dust Model and MM5 Weather Data

NASA Astrophysics Data System (ADS)

Barnum, B. H.; Winstead, N. S.; Wesely, J.; Hakola, A.; Colarco, P.; Toon, O. B.; Ginoux, P.; Brooks, G.; Hasselbarth, L. M.; Toth, B.; Sterner, R.

2002-12-01

An operational model for the forecast of dust storms in Northern Africa, the Middle East and Southwest Asia has been developed for the United States Air Force Weather Agency (AFWA). The dust forecast model uses the 5th generation Penn State Mesoscale Meteorology Model (MM5), and a modified version of the Colorado Aerosol and Radiation Model for Atmospheres (CARMA). AFWA conducted a 60 day evaluation of the dust model to look at the model's ability to forecast dust storms for short, medium and long range (72 hour) forecast periods. The study used satellite and ground observations of dust storms to verify the model's effectiveness. Each of the main mesoscale forecast theaters was broken down into smaller sub-regions for detailed analysis. The study found the forecast model was able to forecast dust storms in Saharan Africa and the Sahel region with an average Probability of Detection (POD)exceeding 68%, with a 16% False Alarm Rate (FAR). The Southwest Asian theater had average POD's of 61% with FAR's averaging 10%.

The Mars Science Laboratory Optical Depth Record

NASA Astrophysics Data System (ADS)

Lemmon, M. T.

2014-07-01

MSL’s Mastcam has been used to measure atmospheric dust loading. The observations show dust storms and the settling of dust during southern fall/winter and show mean dust radius declining from 1.6 to 1.4 microns as the dust settled post-storm.

Evaluation of Soil Moisture, Storm Characteristics, and Their Influence on Storm Runoff and Water Yield at the Panola Mountain Research Watershed, Georgia, U.S.A.

NASA Astrophysics Data System (ADS)

Riley, J. W.; Aulenbach, B. T.

2015-12-01

Understanding the factors that control runoff processes is important for many aspects of water supply and ecosystem protection, especially during climatic extremes that result in flooding or droughts; potentially impacting human safety. Furthermore, having knowledge of the conditions during which runoff occurs contributes to the conceptual understanding of the hydrologic cycle and may improve parameterization of hydrologic models. We evaluated soil moisture, storm characteristics, and the subsequent runoff and water yield for 297 storms over an eight-year period at Panola Mountain Research Watershed to better understand runoff generation processes. Panola Mountain Research Watershed is a small (41-hectare), relatively undisturbed forested watershed near Atlanta, GA, U.S.A. Strong relations were observed between total precipitation for a given storm, deep (70 cm below surface) antecedent soil moisture content and the volume of runoff. However, the strength of the relations varied based on occurrence during the growing (April - September; 172 storms) or dormant (October - March; 125 storms) period. In general, soil moisture responded at a minimum of 15 cm depth for all but 18 events. In addition, we found storms that initiated a response of deep soil moisture (70 cm below surface) to be an important factor relating to storm runoff and water yield. Seventy percent of the dormant period storms generated a response at 70 cm depth compared to 58% of growing period storms. A stronger relation between soil moisture and water yield was noted during the dormant period and indicated that all storms that produced a water yield >12% occurred when deep pre-event soil moisture was >20%. Similar patterns were also present during the growing season with occasional intense thunderstorms also generating higher water yields even in the absence of high soil moisture. The importance of deep soil moisture likely reflects the overall status of watershed storage conditions.

A comparative modeling analysis of multiscale temporal variability of rainfall in Australia

NASA Astrophysics Data System (ADS)

Samuel, Jos M.; Sivapalan, Murugesu

2008-07-01

The effects of long-term natural climate variability and human-induced climate change on rainfall variability have become the focus of much concern and recent research efforts. In this paper, we present the results of a comparative analysis of observed multiscale temporal variability of rainfall in the Perth, Newcastle, and Darwin regions of Australia. This empirical and stochastic modeling analysis explores multiscale rainfall variability, i.e., ranging from short to long term, including within-storm patterns, and intra-annual, interannual, and interdecadal variabilities, using data taken from each of these regions. The analyses investigated how storm durations, interstorm periods, and average storm rainfall intensities differ for different climate states and demonstrated significant differences in this regard between the three selected regions. In Perth, the average storm intensity is stronger during La Niña years than during El Niño years, whereas in Newcastle and Darwin storm duration is longer during La Niña years. Increase of either storm duration or average storm intensity is the cause of higher average annual rainfall during La Niña years as compared to El Niño years. On the other hand, within-storm variability does not differ significantly between different ENSO states in all three locations. In the case of long-term rainfall variability, the statistical analyses indicated that in Newcastle the long-term rainfall pattern reflects the variability of the Interdecadal Pacific Oscillation (IPO) index, whereas in Perth and Darwin the long-term variability exhibits a step change in average annual rainfall (up in Darwin and down in Perth) which occurred around 1970. The step changes in Perth and Darwin and the switch in IPO states in Newcastle manifested differently in the three study regions in terms of changes in the annual number of rainy days or the average daily rainfall intensity or both. On the basis of these empirical data analyses, a stochastic rainfall time series model was developed that incorporates the entire range of multiscale variabilities observed in each region, including within-storm, intra-annual, interannual, and interdecadal variability. Such ability to characterize, model, and synthetically generate realistic time series of rainfall intensities is essential for addressing many hydrological problems, including estimation of flood and drought frequencies, pesticide risk assessment, and landslide frequencies.

The Soviet Military Views Operation Desert Storm: A Preliminary Assessment

DTIC Science & Technology

1991-09-23

NO. IACCESSION NO. 11. TITLE (Include Security Classification) The Soviet Military Views Operation Desert Storm: .A Preliminary Assessment UNCLASSIFIED...VIEWS OPERATION DESERT STORM: A PRELIMINARY ASSESSMENT Stephen J. Blank Av~qoxa 10 a r I~ )~ I.RA&I .1 . a .. _ . . .. J l tia.o.. .. ._ ’Vflstribitleu...preliminary assessments , largely through the spring of 1991, suggest lines of argument that will surely appear later in greater depth, detail, and

A Comparison of Martian Transient Wave Energetics in High and Low Optical Depth Environments

NASA Astrophysics Data System (ADS)

Battalio, J. M.; Szunyogh, I.; Lemmon, M. T.

2016-12-01

The local energetics of individual transient eddies from the Mars Analysis Correction Data Assimilation (MACDA) is compared between a year with a global-scale dust storm (MY 25) and two years of relatively low optical depth conditions. Eddies in each year are considered from a period of strong wave activity in the northern hemisphere before the winter solstice (Ls=170-240°). The local growth of eddies is typically triggered by geopotential flux convergence. While all waves exhibit some baroclinic growth, baroclinic energy conversion is weaker in the waves that occur during the global-scale dust storm. The weaker baroclinic energy conversion in these waves, however, is compensated by a more intense barotropic transfer of the kinetic energy from the mean flow to the waves: the contribution from barotropic energy conversion allows eddies during the global-scale dust storm to attain roughly the same maximum eddy kinetic energy as eddies during the low optical depth years. Individual eddies in the waves decay through a combination of barotropic conversion of the kinetic energy from the waves to the mean flow, geopotential flux divergence, and dissipation in both the high- and the low-optical-depth years.

Comparison of Ionospheric Parameters during Similar Geomagnetic Storms

NASA Astrophysics Data System (ADS)

Blagoveshchensky, D. V.

2018-03-01

The degree of closeness of ionospheric parameters during one magnetic storm and of the same parameters during another, similar, storm is estimated. Overall, four storms—two pairs of storms close in structure and appearance according to recording of the magnetic field X-component—were analyzed. The examination was based on data from Sodankyla observatory (Finland). The f-graphs of the ionospheric vertical sounding, magnetometer data, and riometer data on absorption were used. The main results are as follows. The values of the critical frequencies foF2, foF1, and foE for different but similar magnetic storms differ insignificantly. In the daytime, the difference is on average 6% (from 0 to 11.1%) for all ionospheric layers. In the nighttime conditions, the difference for foF2 is 4%. The nighttime values of foEs differ on average by 20%. These estimates potentially make it possible to forecast ionospheric parameters for a particular storm.

Urban stormwater quality, event-mean concentrations, and estimates of stormwater pollutant loads, Dallas-Fort Worth area, Texas, 1992-93

USGS Publications Warehouse

Baldys, Stanley; Raines, T.H.; Mansfield, B.L.; Sandlin, J.T.

1998-01-01

Local regression equations were developed to estimate loads produced by individual storms. Mean annual loads were estimated by applying the storm-load equations for all runoff-producing storms in an average climatic year and summing individual storm loads to determine the annual load.

Accurately Characterizing the Importance of Wave-Particle Interactions in Radiation Belt Dynamics: The Pitfalls of Statistical Wave Representations

NASA Technical Reports Server (NTRS)

Murphy, Kyle R.; Mann, Ian R.; Rae, I. Jonathan; Sibeck, David G.; Watt, Clare E. J.

2016-01-01

Wave-particle interactions play a crucial role in energetic particle dynamics in the Earths radiation belts. However, the relative importance of different wave modes in these dynamics is poorly understood. Typically, this is assessed during geomagnetic storms using statistically averaged empirical wave models as a function of geomagnetic activity in advanced radiation belt simulations. However, statistical averages poorly characterize extreme events such as geomagnetic storms in that storm-time ultralow frequency wave power is typically larger than that derived over a solar cycle and Kp is a poor proxy for storm-time wave power.

Temporal variation of the arterial pressure in healthy young people and its relation to geomagnetic activity in Mexico

NASA Astrophysics Data System (ADS)

Azcárate, T.; Mendoza, B.; Sánchez de la Peña, S.; Martínez, J. L.

2012-11-01

We present a study of the temporal behavior of the systolic (SBP) and diastolic (DBP) blood pressure for a sample of 51 normotensive, healthy volunteers, 18 men and 33 women with an average age of 19 years old in Mexico City, Mexico, during April and May, 2008. We divided the data by sex along the circadian rhythm. Three geomagnetic storms occurred during the studied time-span. The strongest one, a moderate storm, is attributed to a coronal hole border that reached the Earth. The ANOVA test applied to the strongest storm showed that even though we are dealing with a moderate geomagnetic storm, there are statistically significant responses of the blood pressure. The superposed epoch analysis during a three-day window around the strongest storm shows that on average the largest changes occurred for the SBP. Moreover, the SBP largest increases occurred two days before and one day after this storm, and women are the most sensitive group as they present larger SBP and DBP average changes than men. Finally, given the small size of the sample, we cannot generalize our results.

Synoptic Storms in the North Atlantic in the Atmospheric Reanalysis and Scatterometer-Based Wind Products

NASA Astrophysics Data System (ADS)

Dukhovskoy, D. S.; Bourassa, M. A.

2016-12-01

The study compares and analyses the characteristics of synoptic storms in the Subpolar North Atlantic over the time period from 2000 through 2009 derived from reanalysis data sets and scatterometer-based gridded wind products. The analysis is performed for ocean 10-m winds derived from the following wind data sets: NCEP/DOE AMIP-II reanalysis (NCEPR2), NCAR/CFSR, Arctic System Reanalysis (ASR) version 1, Cross-Calibrated Multi-Platform (CCMP) wind product versions 1.1 and recently released version 2.0 prepared by the Remote Sensing Systems, and QuikSCAT. A cyclone tracking algorithm employed in this study for storm identification is based on average vorticity fields derived from the wind data. The study discusses storm characteristics such as storm counts, trajectories, intensity, integrated kinetic energy, spatial scale. Interannal variability of these characteristics in the data sets is compared. The analyses demonstrates general agreement among the wind data products on the characteristics of the storms, their spatial distribution and trajectories. On average, the NCEPR2 storms are more energetic mostly due to large spatial scales and stronger winds. There is noticeable interannual variability in the storm characteristics, yet no obvious trend in storms is observed in the data sets.

Relation of precipitation quality to storm type, and deposition of dissolved chemical constituents from precipitation in Massachusetts, 1983-85

USGS Publications Warehouse

Gay, F.B.; Melching, C.S.

1995-01-01

Precipitation samples were collected for 83 storms at a rural inland site in Princeton, Mass., and 73 storms at a rural coastal site in Truro, Mass., to examine the quality of precipitation from storms and relate quality to three storm types (oceanic cyclone, continental cyclone, and cold front). At the inland site, Princeton, ranked-means of precipitation depth, storm duration, specific conductance, and concentrations and loads of hydrogen, sulfate, aluminum, bromide, and copper ions were affected by storm type. At the coastal site, Truro, ranked means of precipitation depth, storm duration, and concentrations and loads of calcium, chloride, magnesium, potassium, and sodium ions were affected by storm type. Precipitation chemistry at the coastal site was 85 percent oceanic in orgin, whereas precipitation 72 kilometers inland was 60 percent hydrogen, nitrate, and sulfate ions, reflecting fossil-fuel combustion. Concentrations and loads for specific conductance and 9 chemical constituents on an annual and seasonal basis were determined from National Atmospheric Deposition Program data for spring 1983 through winter 1985 at Quabbin (rural, inland), Waltham (suburban, inland) and Truro (rural, coastal), Massachusetts. Concentrations of magnesium, potassium, sodium, and chloride concentrations were highest at the coast and much lower inland, with very little difference between Waltham and Quabbin. Loads of ammonium, nitrate, sulfate, and hydrogen are highest at Quabbin and are about equal at Waltham and Truro. About twice as much nitrate and hydrogen and about 35 percent more sulfate is deposited at Quabbin than at Waltham or Truro; this pattern indicates that the interior of Massachusetts receives more acidic precipitation than do the eastern or the coastal areas of Massachusetts.

Insights into mid-latitude storm track dynamics from simulations with an idealized dry GCM

NASA Astrophysics Data System (ADS)

Mbengue, C. O.; Schneider, T.

2012-12-01

The mid-latitude storm tracks play an important role in balancing the earth's heat and momentum budget. They have a significant human impact through precipitation and adverse weather conditions; thus, the storm track response to changing climatic conditions is of great interest. In this study, we investigate the climatological response of the mid-latitude storm tracks to varying mean global temperature and convective static stability, using an idealized dry GCM. We demonstrate storm track migration in response to changes in global-mean surface temperatures without modifying the surface pole-equator temperature contrast or including moisture-related effects. The results help interpret the findings of previous global warming studies in which the mid-latitude storm tracks migrate poleward with increasing mean global temperatures. In our study, the storm track position is found to be particularly sensitive to changes in tropical static stability and tropopause height and their effect on the Hadley circulation. The mechanisms driving the dynamics of the mid-latitude storm tracks have been elusive. However, making use of the simplified framework employed in this study, which lends itself to dynamical decompositions, we have been able to improve upon some existing theories on storm track dynamics in dry atmospheres, as well as make additional observations. Previous studies into dry atmospheric dynamics have shown a linear scaling between eddy kinetic energy, a robust measure of the level of storminess, and the mean available potential energy (MAPE). This scaling is utilized in a decomposition that shows that the dominant quantity in storm track dynamics is the meridional gradient of the potential temperature—a measure of baroclinicity. This observation leads us to look for dynamical mechanisms that, on average, dictate the location of regions of elevated baroclinicity. Some credible explanations include the effects on mid-latitude isentropic slopes through a raising or lowering of the tropical tropopause, and effects of a migrating terminus of the Hadley cell. In a simulation where we only vary the convective lapse rate, the decomposition reinforces the meridional temperature gradient as the major determinant of the location of the maximum of MAPE and, by extension, the location of the storm tracks. This is surprising considering that static stability constitutes one of the components of the decomposition. This revelation suggests that static stability plays an indirect role in storm track dynamics through temperature gradients, which is plausible since static stability can affect temperature gradients through its interaction with isentropic slopes. Furthermore, upper tropospheric temperature gradients can be modified by the convective lapse rate through its effect on the depth of the troposphere. The results contained herein can be used to supplement ongoing storm track work in moist atmospheres, using more comprehensive GCMs to understand storm track dynamics in an earth-like environment.

Long-term variability of dust optical depths on Mars during MY24-MY32 and their impact on subtropical lower ionosphere: Climatology, modeling, and observations

NASA Astrophysics Data System (ADS)

Sheel, Varun; Haider, S. A.

2016-08-01

Dust optical depths (τ) for nine Martian years (MY24-MY32) in the subtropical region (25-35°S) have been used to classify distinct dust scenarios. These data are based on observations at 9.3 µm from the Mars Global Surveyor and Mars Odyssey missions and encompass the regional dust storms which occur every year around solar longitude (Ls) ~ 220° and the two major dust storms of MY25 and MY28. Constrained by these observations and the Mars Climate Sounder observations of detached dust layers, we estimate altitude profiles of dust concentrations. We discuss the characteristics of dust aerosol particles of different size between 0.2 and 3.0 µm by assuming a modified gamma distribution. We then use a comprehensive ion-dust model to calculate ion densities and conductivities in the lower ionosphere of Mars in the absence of dust storm at τ = 0.1 and Ls = 150° and for three dust storm periods viz., (1) major dust storm at τ = 1.7 and Ls = 210°, (2) major dust storm at τ = 1.2 and Ls = 280°, and (3) regional dust storm at τ = 0.5 and Ls = 220°. The model with 12 neutral species considers galactic cosmic rays as a source of ionization. Results show that the density of the dominant hydrated cluster ions and the electrical conductivity are reduced by an order of magnitude near the surface for a few months until the dust storm settles down to its normal condition.

Deciphering storm-event runoff behavior in a coastal plain watershed using chemical and physical hydrograph separation techniques

Treesearch

Timothy Callahan; Austin E. Morrison

2016-01-01

Interpreting storm-event runoff in coastal plain watersheds is challenging because of the space- and time-variable nature of different sources that contribute to stream flow. These flow vectors and the magnitude of water flux is dependent on the pre-storm soil moisture (as estimated from depth to water table) in the lower coastal plain (LCP) region.

Flood Frequency Analyses Using a Modified Stochastic Storm Transposition Method

NASA Astrophysics Data System (ADS)

Fang, N. Z.; Kiani, M.

2015-12-01

Research shows that areas with similar topography and climatic environment have comparable precipitation occurrences. Reproduction and realization of historical rainfall events provide foundations for frequency analysis and the advancement of meteorological studies. Stochastic Storm Transposition (SST) is a method for such a purpose and enables us to perform hydrologic frequency analyses by transposing observed historical storm events to the sites of interest. However, many previous studies in SST reveal drawbacks from simplified Probability Density Functions (PDFs) without considering restrictions for transposing rainfalls. The goal of this study is to stochastically examine the impacts of extreme events on all locations in a homogeneity zone. Since storms with the same probability of occurrence on homogenous areas do not have the identical hydrologic impacts, the authors utilize detailed precipitation parameters including the probability of occurrence of certain depth and the number of occurrence of extreme events, which are both incorporated into a joint probability function. The new approach can reduce the bias from uniformly transposing storms which erroneously increases the probability of occurrence of storms in areas with higher rainfall depths. This procedure is iterated to simulate storm events for one thousand years as the basis for updating frequency analysis curves such as IDF and FFA. The study area is the Upper Trinity River watershed including the Dallas-Fort Worth metroplex with a total area of 6,500 mi2. It is the first time that SST method is examined in such a wide scale with 20 years of radar rainfall data.

Sediment Dynamics Over a Stable Point bar of the San Pedro River, Southeastern Arizona

NASA Astrophysics Data System (ADS)

Hamblen, J. M.; Conklin, M. H.

2002-12-01

Streams of the Southwest receive enormous inputs of sediment during storm events in the monsoon season due to the high intensity rainfall and large percentages of exposed soil in the semi-arid landscape. In the Upper San Pedro River, with a watershed area of approximately 3600 square kilometers, particle size ranges from clays to boulders with large fractions of sand and gravel. This study focuses on the mechanics of scour and fill on a stable point bar. An innovative technique using seven co-located scour chains and liquid-filled, load-cell scour sensors characterized sediment dynamics over the point bar during the monsoon season of July to September 2002. The sensors were set in two transects to document sediment dynamics near the head and toe of the bar. Scour sensors record area-averaged sediment depths while scour chains measure scour and fill at a point. The average area covered by each scour sensor is 11.1 square meters. Because scour sensors have never been used in a system similar to the San Pedro, one goal of the study was to test their ability to detect changes in sediment load with time in order to determine the extent of scour and fill during monsoonal storms. Because of the predominantly unconsolidated nature of the substrate it was hypothesized that dune bedforms would develop in events less than the 1-year flood. The weak 2002 monsoon season produced only two storms that completely inundated the point bar, both less than the 1-year flood event. The first event, 34 cms, produced net deposition in areas where Johnson grass had been present and was now buried. The scour sensor at the lowest elevation, in a depression which serves as a secondary channel during storm events, recorded scour during the rising limb of the hydrograph followed by pulses we interpret to be the passage of dunes. The second event, although smaller at 28 cms, resulted from rain more than 50 km upstream and had a much longer peak and a slowly declining falling limb. During the second flood, several areas with buried vegetation were scoured back to their original bed elevations. Pulses of sediment passed over the sensor in the secondary channel and the sensor in the vegetated zone. Scour sensor measurements agree with data from scour chains (error +/- 3 cm) and surveys (error +/- 0.6 cm) performed before and after the two storm events, within the range of error of each method. All load sensor data were recorded at five minute intervals. Use of a smaller interval could give more details about the shapes of sediment waves and aid in bedform determination. Results suggest that dune migration is the dominant mechanism for scour and backfill in the point bar setting. Scour sensors, when coupled with surveying and/or scour chains, are a tremendous addition to the geomorphologist's toolbox, allowing unattended real-time measurements of sediment depth with time.

Exploratory Meeting on Atmospheric Electricity and Severe Storms

NASA Technical Reports Server (NTRS)

Vaughan, W. W. (Editor)

1978-01-01

The meeting was arranged to discuss atmospheric electricity and its relationship to severe storms, the feasibility of developing a set of instruments for either a Space Shuttle or an unmanned satellite, and the scientific rationale which would warrant further in-depth assessment, involvement and development of supporting activities by NASA.

Assessment of CLIGEN precipitation and storm pattern generation under four precipitation depth categories in China

USDA-ARS?s Scientific Manuscript database

CLIGEN (CLImate GENerator) is a widely used stochastic weather generator to simulate continuous daily precipitation and storm pattern information for hydrological and soil erosion models. Although CLIGEN has been tested in several regions in the world, thoroughly assessment before applying it to Chi...

Risk assessment of storm surge disaster based on numerical models and remote sensing

NASA Astrophysics Data System (ADS)

Liu, Qingrong; Ruan, Chengqing; Zhong, Shan; Li, Jian; Yin, Zhonghui; Lian, Xihu

2018-06-01

Storm surge is one of the most serious ocean disasters in the world. Risk assessment of storm surge disaster for coastal areas has important implications for planning economic development and reducing disaster losses. Based on risk assessment theory, this paper uses coastal hydrological observations, a numerical storm surge model and multi-source remote sensing data, proposes methods for valuing hazard and vulnerability for storm surge and builds a storm surge risk assessment model. Storm surges in different recurrence periods are simulated in numerical models and the flooding areas and depth are calculated, which are used for assessing the hazard of storm surge; remote sensing data and GIS technology are used for extraction of coastal key objects and classification of coastal land use are identified, which is used for vulnerability assessment of storm surge disaster. The storm surge risk assessment model is applied for a typical coastal city, and the result shows the reliability and validity of the risk assessment model. The building and application of storm surge risk assessment model provides some basis reference for the city development plan and strengthens disaster prevention and mitigation.

Trace-fossil and storm-deposit relationships of San Carlos formation, west Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metz, C.L.; Bednarski, S.P.

1986-05-01

Two distinct assemblages of trace fossils are preserved in the storm deposits in delta-front facies of the Upper Cretaceous San Carlos Formation, west Texas. The assemblages represent two widely differing responses to storm deposition and sediment-trace-fossil relationships, indicating that other environmental parameters, probably water depth and oxygen levels, influenced trace-fossil distribution within the San Carlos delta front. Evidence of the storm-deposited nature of the sandstones includes a scoured basal contact, planar to hummocky cross-stratification, and a upper contact that is either ripple marked or is gradational with overlying shales.

Storm orientation impacts on atmospheric river induced precipitation efficiency

NASA Astrophysics Data System (ADS)

Mehran, A.; Lettenmaier, D. P.

2016-12-01

Atmospheric Rivers (ARs) along the Pacific North coast are often associated with heavy winter precipitation and flooding. We analyze 35 years (1981 2016) of landfalling ARs over a transect along the U.S. West Coast consisting of four river basins from coastal Washington to Southern California (Chehalis, Russian, Santa Ana, and Santa Margarita Rivers) to assess the impact of storm orientation on precipitation rainout efficiency. We define precipitation rainout efficiency as the correlation coefficient between the net integrated vapor transport and precipitation rate. We use 6-hourly climate data from the Climate Forecast System Reanalysis (CFSR) for each of the landfalling ARs. We compute storm orientation from CFSR wind vectors (daily averaged over atmospheric levels between 1000 hPa and 300 hPa) associated with each AR event. We also compute integrated vapor transport (IVT) by multiplying precipitable water by the wind vector and compare with daily averaged precipitation averaged over the river basins, where daily precipitation is taken from Parameter-Elevation Relationships on Independent Slopes Model (PRISM) to evaluate the impact of storm orientation on rainfall efficiency. We calculate the local topographic orientation of each river basin (slope and aspect) from ArcGIS, which we related to storm orientation. To evaluate the impact of storm orientation on rainout efficiency over the Russian River basin (Northern California), we first calculated approaching IVT (for all of AR induced precipitations from 1981 to 2016) and daily averaged precipitation rate. Next, we calculated the correlation coefficient between IVT and precipitation rate (for all AR induced rainouts over the Russian River basin). Finally, by considering the local topographical changes (slope and aspect from ArcGIS) and integrating them into an effective IVT, we compared the correlation coefficients between actual and effective IVT and basin-average precipitation. We find that over the Russian River basin, the rainout efficiency increases from 55 to 75 % when we account for storm orientation relative to topography.

Rapid shelf-wide cooling response of a stratified coastal ocean to hurricanes.

PubMed

Seroka, Greg; Miles, Travis; Xu, Yi; Kohut, Josh; Schofield, Oscar; Glenn, Scott

2017-06-01

Large uncertainty in the predicted intensity of tropical cyclones (TCs) persists compared to the steadily improving skill in the predicted TC tracks. This intensity uncertainty has its most significant implications in the coastal zone, where TC impacts to populated shorelines are greatest. Recent studies have demonstrated that rapid ahead-of-eye-center cooling of a stratified coastal ocean can have a significant impact on hurricane intensity forecasts. Using observation-validated, high-resolution ocean modeling, the stratified coastal ocean cooling processes observed in two U.S. Mid-Atlantic hurricanes were investigated: Hurricane Irene (2011)-with an inshore Mid-Atlantic Bight (MAB) track during the late summer stratified coastal ocean season-and Tropical Storm Barry (2007)-with an offshore track during early summer. For both storms, the critical ahead-of-eye-center depth-averaged force balance across the entire MAB shelf included an onshore wind stress balanced by an offshore pressure gradient. This resulted in onshore surface currents opposing offshore bottom currents that enhanced surface to bottom current shear and turbulent mixing across the thermocline, resulting in the rapid cooling of the surface layer ahead-of-eye-center. Because the same baroclinic and mixing processes occurred for two storms on opposite ends of the track and seasonal stratification envelope, the response appears robust. It will be critical to forecast these processes and their implications for a wide range of future storms using realistic 3-D coupled atmosphere-ocean models to lower the uncertainty in predictions of TC intensities and impacts and enable coastal populations to better respond to increasing rapid intensification threats in an era of rising sea levels.

The storm-time assessment of GNSS-SBAS performance within low latitude African region using a testbed-like platform

NASA Astrophysics Data System (ADS)

Abe, O. E.; Paparini, C.; Ngaya, R. H.; Otero Villamide, X.; Radicella, S. M.; Nava, B.

2017-09-01

A Satellite Based Augmentation System (SBAS) is designed to improve Global Navigation Satellite Systems (GNSS) in terms of integrity, accuracy, availability and continuity. The main limitation to SBAS performance optimization is the ionosphere, and this is more critical in low latitude. During geomagnetically disturbed periods the role of storm-time winds is important because they modify the atmospheric composition toward low latitudes. An index of ionospheric disturbance, the relative percentage of deviation of the vertical Total Electron Content (TEC) from the quiet level (DvTEC) at each station was evaluated to study positive and negative phases of the geomagnetic storms. The rate of change of TEC index (ROTI) over all the GNSS stations was estimated to evaluate equatorial ionospheric gradients and irregularities. From the study it is observed that the positive deviations are more frequent than negative ones. The availability map, which is the mean of the combine Vertical Protection Level (VPL) and Horizontal Protection Level (HPL) are used for the SBAS performance. The cases of moderate and minor storms studied during the months of July and October 2013 showed that the SBAS system performance during the disturbed periods depends on the local time in which the storm occurs, geographic longitude and other phenomena that need further study. During the storm-time conditions considered, three out of seven geomagnetic storms indicated good SBAS performance and exceed monthly average of the availability map, three geomagnetic storms reduced the system performance below monthly average while one does not have effect on SBAS system performance in respect to monthly average. The present study indicates ROTI as a better proxy than geomagnetic indices for the assessment of storm-time effects on GNSS-SBAS performance.

Modelling derecho dynamics and the direct radiative effect of wildfire smoke upon it with NWP model HARMONIE

NASA Astrophysics Data System (ADS)

Toll, Velle; Männik, Aarne

2014-05-01

Convection permitting numerical weather prediction model HARMONIE was used to simulate the dynamics of the derecho that swept over Eastern Europe on August 8, 2010. The storm moved over Belarus, Lithuania, Latvia, Estonia and Finland and the strongest wind gusts (up to 36.5 m/s) were measured in Estonia. The storm path is recorded on the radar images where characteristic bow echo was observed. The model setup was similar to near-future operational, nearly kilometre-scale environments in European national weather services. Hindcast experiments show the ability of the HARMONIE model to predict the severe convective storm and forecast concurrent strong wind gusts. Wind gusts with very similar intensity to observed ones were simulated by the HARMONIE model and 2.5-km horizontal resolution appears sufficient for reliable forecast of the derecho event. The timing of the modelled storm was in good agreement with the observations. The simulated average storm propagation speed was 25 m/s, similar to the radar observations. Hindcast experiments suggest that more precise warning for the storm could have been issued if the HARMONIE model would have been utilised. The derecho event was accompanied by the remarkable smoke aerosol concentrations (maximum total aerosol optical depth more than 4 at 550 nm) originating from the wildfires from Russia. Smoke plume travelled clockwise around Moscow from August 5 to 9. On August 8, 2010, smoke plume was situated on the Eastern border of Estonia. The derecho occurred on the western side of the smoke plume path. HARMONIE experiments were performed to study the direct radiative effect of wildfire smoke on a severe convective storm. The impact of smoke aerosol on the derecho dynamics was investigated. Reduction in the shortwave radiation flux at the surface resulting from aerosol influence simulated by the HARMONIE model is up to 200 W/m2 in the area with the highest aerosol concentrations. This causes near surface cooling of up to 3 ºC. The direct radiative effect of aerosol increases the stability of the atmospheric boundary layer and this had influence on the simulated derecho dynamics.

SToRM: A Model for Unsteady Surface Hydraulics Over Complex Terrain

USGS Publications Warehouse

Simoes, Francisco J.

2014-01-01

A two-dimensional (depth-averaged) finite volume Godunov-type shallow water model developed for flow over complex topography is presented. The model is based on an unstructured cellcentered finite volume formulation and a nonlinear strong stability preserving Runge-Kutta time stepping scheme. The numerical discretization is founded on the classical and well established shallow water equations in hyperbolic conservative form, but the convective fluxes are calculated using auto-switching Riemann and diffusive numerical fluxes. The model’s implementation within a graphical user interface is discussed. Field application of the model is illustrated by utilizing it to estimate peak flow discharges in a flooding event of historic significance in Colorado, U.S.A., in 2013.

Modification of Surf Zone Turbulence and the Undertow by a Submerged Canopy

NASA Astrophysics Data System (ADS)

Mandel, T.; Koseff, J. R.; Rosenzweig, I.; Suckale, J.; Zarama, F. J.

2016-02-01

As sea level rise and stronger storm events threaten our coastlines, coastal vegetation has come under consideration as a potentially resilient, financially viable tool to mitigate flooding and erosion. However, the actual role of this "green infrastructure" in the near-shore region is not fully understood. In order to evaluate the role of vegetation in coastal protection, a series of experiments were conducted in a simulated laboratory surf zone. We examine the impact of canopy location and submergence on the undertow profile, turbulent kinetic energy, and Reynolds stress for varying Reynolds number and Keulegan-Carpenter number, and compare these results to theoretical formulations that utilize a depth-averaged undertow and highly simplified eddy viscosity.

Storm-wave-induced seabed deformation: Results from in situ observation in the Yellow River subaqueous delta

NASA Astrophysics Data System (ADS)

Jia, Y.; Wang, Z. Mr; Liu, X.; Shan, H.

2017-12-01

Submarine landslides move large volumes of sediment and are often hazardous to offshore installations. Current research into submarine landslides mainly relies on marine surveying techniques. In contrast, in situ observations of the submarine landslide process, specifically seabed deformation, are sparse, and therefore restrict our understanding of submarine landslide mechanisms and the establishment of a disaster warning scheme. The submarine landslide monitoring (SLM) system, which has been designed to partly overcome these pitfalls, can monitor storm-wave-induced submarine landslides in situ and over a long time period. The SLM system comprises two parts: (1) a hydrodynamic monitoring tripod for recording hydrodynamic data and (2) a shape accel array for recording seabed deformation at different depths. This study recorded the development of the SLM system and the results of in situ observation in the Yellow River Delta, China, during the boreal winter of 2014-2015. The results show an abrupt small-scale storm-wave-induced seabed shear deformation; the shear interface is in at least 1.5-m depth and the displacement of sediments at 1.23-m depth is more than 13 mm. The performance of the SLM system confirms the feasibility and stability of this approach. Further, the in situ observations, as well as the laboratory tests, helped reveal the profound mechanism of storm-wave-induced seabed deformation.

A probabilistic storm surge risk model for the German North Sea and Baltic Sea coast

NASA Astrophysics Data System (ADS)

Grabbert, Jan-Henrik; Reiner, Andreas; Deepen, Jan; Rodda, Harvey; Mai, Stephan; Pfeifer, Dietmar

2010-05-01

The German North Sea coast is highly exposed to storm surges. Due to its concave bay-like shape mainly orientated to the North-West, cyclones from Western, North-Western and Northern directions together with astronomical tide cause storm surges accumulating the water in the German bight. Due to the existence of widespread low-lying areas (below 5m above mean sea level) behind the defenses, large areas including large economic values are exposed to coastal flooding including cities like Hamburg or Bremen. The occurrence of extreme storm surges in the past like e.g. in 1962 taking about 300 lives and causing widespread flooding and 1976 raised the awareness and led to a redesign of the coastal defenses which provide a good level of protection for today's conditions. Never the less the risk of flooding exists. Moreover an amplification of storm surge risk can be expected under the influence of climate change. The Baltic Sea coast is also exposed to storm surges, which are caused by other meteorological patterns. The influence of the astronomical tide is quite low instead high water levels are induced by strong winds only. Since the exceptional extreme event in 1872 storm surge hazard has been more or less forgotten. Although such an event is very unlikely to happen, it is not impossible. Storm surge risk is currently (almost) non-insurable in Germany. The potential risk is difficult to quantify as there are almost no historical losses available. Also premiums are difficult to assess. Therefore a new storm surge risk model is being developed to provide a basis for a probabilistic quantification of potential losses from coastal inundation. The model is funded by the GDV (German Insurance Association) and is planned to be used within the German insurance sector. Results might be used for a discussion of insurance cover for storm surge. The model consists of a probabilistic event driven hazard and a vulnerability module, furthermore an exposure interface and a financial module to account for specific (re-) insurance conditions. This contribution will mainly concentrate on the hazard module. The hazard is covered by an event simulation engine enabling Monte Carlo simulations. The event generation is done on-the-fly. A classification of historical storm surges is used based on observed sea water levels at gauging stations and extended literature research. To characterize the origin of storm events and storm surges caused by those, also meteorological parameters like wind speed and wind direction are being used. If high water levels along the coast are mainly caused by strong wind from particular directions as observed at the North Sea, there is a clear empirical relationship between wind and surge (where surge is defined as the wind-driven component of the sea water level) which can be described by the ATWS (Average Transformed Wind speed). The parameters forming the load at the coastal defense elements are water level and wave parameters like significant wave height, wave period and wave direction. To assess the wave characteristics at the coast the numerical model SWAN (Simulating Waves Near Shore) from TU Delft has been used. To account for different probabilities of failure and inundation the coast is split into segments with similar defense characteristics like type of defense, height, width, orientation and others. The chosen approach covers the most relevant failure mechanisms for coastal dikes induced by wave overtopping and overflow. Dune failure is also considered in the model. Inundation of the hinterland after defense failure is modeled using a simple dynamical 2d-approach resulting in distributed water depths and flood outlines for each segment. Losses can be estimated depending on the input exposure data either coordinate based for single buildings or aggregated on postal code level using a set of depths-damage functions.

Ice core evidence of rapid air temperature increases since 1960 in alpine areas of the Wind River Range, Wyoming, United States

USGS Publications Warehouse

Naftz, D.L.; Susong, D.D.; Schuster, P.F.; Cecil, L.D.; Dettinger, M.D.; Michel, R.L.; Kendall, C.

2002-01-01

Site-specific transfer functions relating delta oxygen 18 (δ18O) values in snow to the average air temperature (TA) during storms on Upper Fremont Glacier (UFG) were used in conjunction with δ18O records from UFG ice cores to reconstruct long-term trends in air temperature from alpine areas in the Wind River Range, Wyoming. Transfer functions were determined by using data collected from four seasonal snowpacks (1989-1990, 1997-1998, 1998-1999, and 1999-2000). The timing and amount of each storm was determined from an automated snowpack telemetry (SNOTEL) site, 22 km northeast of UFG, and ~1060 m in elevation below UFG. Statistically significant and positive correlations between δ18O values in the snow and TA were consistently found in three of the four seasonal snowpacks. The snowpack with the poor correlation was deposited in 1997-1998 during the 1997-1998 El Nino Southern Oscillation (ENSO). An ultrasonic snow-depth sensor installed on UFG provided valuable insights into site-specific storms and postdepositional processes that occur on UFG. The timing of storms recorded at the UFG and Cold Springs SNOTEL sites were similar; however, selected storms did not correlate. Snow from storms occurring after mid-October and followed by high winds was most susceptible to redeposition of snow. This removal of lower temperature snowfall could potentially bias the δ18O values preserved in ice core records to environmental conditions reflecting higher air temperatures and lower wind speeds. Transfer functions derived from seasonal snow cover on UFG were used to reconstruct TA values from δ18O values determined from two ice cores collected from UFG. Reconstructed air temperatures from the ice core data indicate an increase in TA of ~3.5oC from the mid-1960s to the early 1990s in the alpine areas of northwestern Wyoming. Reconstructed TA from the ice core records between the end of the Little Ice Age (LIA), mid-1800s, and the early 1990s indicate a TA increase of ~55oC. The historically reconstructed TA values from the UFG were significantly higher than the global average observed during the 20th Century but were in agreement with TA increases observed at selected, high-altitude and high-latitude sites in other parts of the world. Additional research is required to determine if part of the observed trend toward heavier δ18O values in ice from the UFG since the LIA (and increased TA) is due to an increased proportion of snowfall from southerly storm tracks and moisture sources, as seems to have been the situation in 1997-1998. Copyright 2002 by the American Geophysical Union.

Flood Inundation Mapping and Emergency Operations during Hurricane Harvey

NASA Astrophysics Data System (ADS)

Fang, N. Z.; Cotter, J.; Gao, S.; Bedient, P. B.; Yung, A.; Penland, C.

2017-12-01

Hurricane Harvey struck the Gulf Coast as Category 4 on August 25, 2017 with devastating and life-threatening floods in Texas. Harris County received up to 49 inches of rainfall over a 5-day period and experienced flooding level and impacts beyond any previous storm in Houston's history. The depth-duration-frequency analysis reveals that the areal average rainfall for Brays Bayou surpasses the 500-year rainfall in both 24 and 48 hours. To cope with this unprecedented event, the researchers at the University of Texas at Arlington and Rice University worked closely with the U.S. Army Corps of Engineers (USACE), the National Weather Service (NWS), the Texas Division of Emergency Management (TDEM), Walter P. Moore and Associates, Inc. and Halff Associates, to conduct a series of meteorological, hydrologic and hydraulic analyses to delineate flood inundation maps. Up to eight major watersheds in Harris County were delineated based the available QPE data from WGRFC. The inundation map over Brays Bayou with their impacts from Hurricane Harvey was delineated in comparison with those of 100-, 500-year, and Probable Maximum Precipitation (PMP) design storms. This presentation will provide insights for both engineers and planners to re-evaluate the existing flood infrastructure and policy, which will help build Houston stronger for future extreme storms. The collaborative effort among the federal, academic, and private entities clearly demonstrates an effective approach for flood inundation mapping initiatives for the nation.

Nonlinear terms in storm surge predictions: Effect of tide and shelf geometry with case study from Hurricane Rita

NASA Astrophysics Data System (ADS)

Rego, JoãO. L.; Li, Chunyan

2010-06-01

This study applied the finite volume coastal ocean model (FVCOM) to the storm surge induced by Hurricane Rita along the Louisiana-Texas coast. The model was calibrated for tides and validated with observed water levels. Peak water levels were shown to be lower than expected for a landfall at high tide. For low- and high-tide landfalls, nonlinear effects due to tide-surge coupling were constructive and destructive to total storm tide, respectively, and their magnitude reached up to 70% of the tidal amplitude in the Rita application. Tide-surge interaction was further examined using a standard hurricane under idealized scenarios to evaluate the effects of various shelf geometries, tides, and landfall timings (relative to tide). Nonlinearity was important between landfall position and locations within 2.5 × radius of maximum winds. On an idealized wide continental shelf, nonlinear effects reached up to 80% of the tidal amplitude with an S2 tide and up to 47% with a K1 tide. Increasing average depths by 4 m reduced nonlinear effects to 41% of the tidal amplitude; increasing the slope by a factor of 3 produced nonlinearities of just 26% of tide (both with a K1 tide). The nonlinear effect was greatest for landfalls at low tide, followed by landfalls at high tide and then by landfalls at midebb or midflood.

Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples

USGS Publications Warehouse

Morton, Robert A.; Gelfenbaum, Guy; Jaffe, Bruce E.

2007-01-01

Modern subaerial sand beds deposited by major tsunamis and hurricanes were compared at trench, transect, and sub-regional spatial scales to evaluate which attributes are most useful for distinguishing the two types of deposits. Physical criteria that may be diagnostic include: sediment composition, textures and grading, types and organization of stratification, thickness, geometry, and landscape conformity. Published reports of Pacific Ocean tsunami impacts and our field observations suggest that sandy tsunami deposits are generally 30 cm thick, generally extend The distinctions between tsunami and storm deposits are related to differences in the hydrodynamics and sediment-sorting processes during transport. Tsunami deposition results from a few high-velocity, long-period waves that entrain sediment from the shoreface, beach, and landward erosion zone. Tsunamis can have flow depths greater than 10 m, transport sediment primarily in suspension, and distribute the load over a broad region where sediment falls out of suspension when flow decelerates. In contrast, storm inundation generally is gradual and prolonged, consisting of many waves that erode beaches and dunes with no significant overland return flow until after the main flooding. Storm flow depths are commonly

Cost and Performance Report Low Impact Technologies to Reduce Pollution from Storm Water Runoff SI-200405

DTIC Science & Technology

2008-09-01

will have to be removed and replaced with new media. Coarser material would also enable more sediment to be filtered through the bed depth as opposed...purpose of this demonstration was to obtain information on the effectiveness of a new storm water filter system that is not currently available in the...system at military installations involves new capital and operating costs. And like many industrial installations, neither NRRC nor ANAD had storm

Regional and local increases in storm intensity in the San Francisco Bay Area, USA, between 1890 and 2010

NASA Astrophysics Data System (ADS)

Russo, Tess A.; Fisher, Andrew T.; Winslow, Dustin M.

2013-04-01

Studies of extreme precipitation have documented changes at the continental scale during the twentieth century, but few studies have quantified changes at small to regional spatial scales during the same time. We analyze historic data from over 600 precipitation stations in the San Francisco Bay Area (SFBA), California, to assess whether there have been statistically significant changes in extreme precipitation between 1890 and 2010. An annual exceedance probability analysis of extreme precipitation events in the SFBA, coupled with a Markov chain Monte Carlo algorithm, reveals an increase in the occurrence of large events. The depth-duration-frequency characteristics of maximum annual precipitation events having durations of 1 h to 60 days indicate on average an increase in storm intensity in the last 120 years, with the intensity of the largest (least frequent) events increasing the most. Mean annual precipitation (MAP) also increased during the study period, but the relative increase in extreme event intensity exceeds that of MAP, indicating that a greater fraction of precipitation fell during large events. Analysis of data from subareas within the SFBA region indicates considerable heterogeneity in the observed nonstationarity; for example, the 5 day, 25 year event exceedance depth changed by +26%, +16%, and -1% in San Francisco, Santa Rosa, and San Jose, respectively. These results emphasize the importance of analyzing local data for accurate risk assessment, emergency planning, resource management, and climate model calibration.

Impact of Langmuir Turbulence on Upper Ocean Response to Hurricane Edouard: Model and Observations

NASA Astrophysics Data System (ADS)

Blair, A.; Ginis, I.; Hara, T.; Ulhorn, E.

2017-12-01

Tropical cyclone intensity is strongly affected by the air-sea heat flux beneath the storm. When strong storm winds enhance upper ocean turbulent mixing and entrainment of colder water from below the thermocline, the resulting sea surface temperature cooling may reduce the heat flux to the storm and weaken the storm. Recent studies suggest that this upper ocean turbulence is strongly affected by different sea states (Langmuir turbulence), which are highly complex and variable in tropical cyclone conditions. In this study, the upper ocean response under Hurricane Edouard (2014) is investigated using a coupled ocean-wave model with and without an explicit sea state dependent Langmuir turbulence parameterization. The results are compared with in situ observations of sea surface temperature and mixed layer depth from AXBTs, as well as satellite sea surface temperature observations. Overall, the model results of mixed layer deepening and sea surface temperature cooling under and behind the storm are consistent with observations. The model results show that the effects of sea state dependent Langmuir turbulence can be significant, particularly on the mixed layer depth evolution. Although available observations are not sufficient to confirm such effects, some observed trends suggest that the sea state dependent parameterization might be more accurate than the traditional (sea state independent) parameterization.

Temporal and spatial variations in suspended matter in continental shelf and slope waters off the north-eastern United States

USGS Publications Warehouse

Bothner, Michael H.; Parmenter, Carol M.; Milliman, John D.

1981-01-01

Seston in waters of Georges Bank originates primarily from biological production and from resuspension of bottom sediments. The concentrations of suspended matter observed on the central shoals are more influenced by storms than by seasonal changes. Winter storms produce highest concentrations of non-combustible material throughout the water column, and summer storms appear to increase biological production by mixing additional nutrients into the photic zone. On the south-east flank of the bank, in water depths between 80 and 200 in, the concentrations of total suspended matter and non-combustible material show little variation compared with the central shoals, and storm effects are far less noticeable.Highest concentrations (>15 mg 1−1) of suspended matter occur in bottom waters south of Nantucket Island after winter storms and appear to be primarily resuspended bottom sediment. Resuspended sediment is also common in near-bottom waters of the south-western Gulf of Maine, and occasionally near the intersection of the shelf/slope water mass front and the bottom.Seasonal variations were observed in the distribution and species composition of phytoplankton. Coccoliths are predominant on the central bank during the winter, but during the spring and summer they are concentrated on the eastern flank at deeper depths.

Impact of storm runoff on Salmonella and Escherichia coli prevalence in irrigation ponds of fresh produce farms in southern Georgia.

PubMed

Harris, C S; Tertuliano, M; Rajeev, S; Vellidis, G; Levy, K

2018-03-01

To examine Salmonella and Escherichia coli in storm runoff and irrigation ponds used by fresh produce growers, and compare Salmonella serovars with those found in cases of human salmonellosis. We collected water before and after rain events at two irrigation ponds on farms in southern Georgia, USA, and collected storm runoff/storm flow within the contributing watershed of each pond. Salmonella and E. coli concentrations were higher in ponds after rain events by an average of 0·46 (P < 0·01) and 0·61 (P < 0·05) log 10 most probable number (MPN) per 100 ml respectively. Salmonella concentrations in storm runoff from fields and forests were not significantly higher than in ponds before rain events, but concentrations in storm flow from streams and ditches were higher by an average of 1·22 log 10 MPN per 100 ml (P < 0·001). Eighteen Salmonella serovars were identified from 155 serotyped isolates, and eight serovars were shared between storm runoff/storm flow and ponds. Seven of the serovars, including five of the shared serovars, were present in cases of human illness in the study region in the same year. However, several serovars most commonly associated with human illness in the study region (e.g. Javiana, Enteritidis, and Montevideo) were not found in any water samples. Salmonella and E. coli concentrations in irrigation ponds were higher, on average, after rain events, but concentrations of Salmonella were low, and the ponds met FDA water quality standards based on E. coli. Some similarities and notable differences were found between Salmonella serovars in water samples and in cases of human illness. This study directly examined storm runoff/storm flow into irrigation ponds and quantified increases in Salmonella and E. coli following rain events, with potential implications for irrigation pond management as well as human health. © 2018 The Society for Applied Microbiology.

Detection of severe storm signatures in loblolly pine using seven-year periodic standardized averages and standard deviations

Treesearch

Stevenson Douglas; Thomas Hennessey; Thomas Lynch; Giulia Caterina; Rodolfo Mota; Robert Heineman; Randal Holeman; Dennis Wilson; Keith Anderson

2016-01-01

A loblolly pine plantation near Eagletown, Oklahoma was used to test standardized tree ring widths in detecting snow and ice storms. Widths of two rings immediately following suspected storms were standardized against widths of seven rings following the storm (Stan1 and Stan2). Values of Stan1 less than -0.900 predict a severe (usually ice) storm when Stan 2 is less...

Impacts of winter storms on air-sea gas exchange

NASA Astrophysics Data System (ADS)

Zhang, Weiqing; Perrie, Will; Vagle, Svein

2006-07-01

The objective of this study is to investigate air-sea gas exchange during winter storms, using field measurements from Ocean Station Papa in the Northeast Pacific (50°N, 145°W). We show that increasing gas transfer rates are coincident with increasing winds and deepening depth of bubble penetration, and that this process depends on sea state. Wave-breaking is shown to be an important factor in the gas transfer velocity during the peaks of the storms, increasing the flux rates by up to 20%. Gas transfer rates and concentrations can exhibit asymmetry, reflecting a sudden increase with the onset of a storm, and gradual recovery stages.

Regression modeling of particle size distributions in urban storm water: advancements through improved sample collection methods

USGS Publications Warehouse

Fienen, Michael N.; Selbig, William R.

2012-01-01

A new sample collection system was developed to improve the representation of sediment entrained in urban storm water by integrating water quality samples from the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of suspended-sediment concentration and particle size distribution at three independent study locations. Use of the DISA decreased variability, which improved statistical regression to predict particle size distribution using surrogate environmental parameters, such as precipitation depth and intensity. The performance of this statistical modeling technique was compared to results using traditional fixed-point sampling methods and was found to perform better. When environmental parameters can be used to predict particle size distributions, environmental managers have more options when characterizing concentrations, loads, and particle size distributions in urban runoff.

Foraging areas, offshore habitat use, and colony overlap by incubating Leach’s storm-petrels Oceanodroma leucorhoa in the Northwest Atlantic

PubMed Central

Hedd, April; Pollet, Ingrid L.; Mauck, Robert A.; Burke, Chantelle M.; Mallory, Mark L.; McFarlane Tranquilla, Laura A.; Montevecchi, William A.; Robertson, Gregory J.; Ronconi, Robert A.; Shutler, Dave; Wilhelm, Sabina I.; Burgess, Neil M.

2018-01-01

Despite their importance in marine food webs, much has yet to be learned about the spatial ecology of small seabirds. This includes the Leach’s storm-petrel Oceanodroma leucorhoa, a species that is declining throughout its Northwest Atlantic breeding range. In 2013 and 2014, we used global location sensors to track foraging movements of incubating storm-petrels from 7 eastern Canadian breeding colonies. We determined and compared the foraging trip and at-sea habitat characteristics, analysed spatial overlap among colonies, and determined whether colony foraging ranges intersected with offshore oil and gas operations. Individuals tracked during the incubation period made 4.0 ± 1.4 day foraging trips, travelling to highly pelagic waters over and beyond continental slopes which ranged, on average, 400 to 830 km from colonies. Cumulative travel distances ranged from ~900 to 2,100 km among colonies. While colony size did not influence foraging trip characteristics or the size of areas used at sea, foraging distances tended to be shorter for individuals breeding at the southern end of the range. Core areas did not overlap considerably among colonies, and individuals from all sites except Kent Island in the Bay of Fundy foraged over waters with median depths > 1,950 m and average chlorophyll a concentrations ≤ 0.6 mg/m3. Sea surface temperatures within colony core areas varied considerably (11–23°C), coincident with the birds’ use of cold waters of the Labrador Current or warmer waters of the Gulf Stream Current. Offshore oil and gas operations intersected with the foraging ranges of 5 of 7 colonies. Three of these, including Baccalieu Island, Newfoundland, which supports the species’ largest population, have experienced substantial declines in the last few decades. Future work should prioritize modelling efforts to incorporate information on relative predation risk at colonies, spatially explicit risks at-sea on the breeding and wintering grounds, effects of climate and marine ecosystem change, as well as lethal and sub-lethal effects of environmental contaminants, to better understand drivers of Leach’s storm-petrel populations trends in Atlantic Canada. PMID:29742124

Using LiDAR to Estimate Surface Erosion Volumes within the Post-storm 2012 Bagley Fire

NASA Astrophysics Data System (ADS)

Mikulovsky, R. P.; De La Fuente, J. A.; Mondry, Z. J.

2014-12-01

The total post-storm 2012 Bagley fire sediment budget of the Squaw Creek watershed in the Shasta-Trinity National Forest was estimated using many methods. A portion of the budget was quantitatively estimated using LiDAR. Simple workflows were designed to estimate the eroded volume's of debris slides, fill failures, gullies, altered channels and streams. LiDAR was also used to estimate depositional volumes. Thorough manual mapping of large erosional features using the ArcGIS 10.1 Geographic Information System was required as these mapped features determined the eroded volume boundaries in 3D space. The 3D pre-erosional surface for each mapped feature was interpolated based on the boundary elevations. A surface difference calculation was run using the estimated pre-erosional surfaces and LiDAR surfaces to determine volume of sediment potentially delivered into the stream system. In addition, cross sections of altered channels and streams were taken using stratified random selection based on channel gradient and stream order respectively. The original pre-storm surfaces of channel features were estimated using the cross sections and erosion depth criteria. Open source software Inkscape was used to estimate cross sectional areas for randomly selected channel features and then averaged for each channel gradient and stream order classes. The average areas were then multiplied by the length of each class to estimate total eroded altered channel and stream volume. Finally, reservoir and in-channel depositional volumes were estimated by mapping channel forms and generating specific reservoir elevation zones associated with depositional events. The in-channel areas and zones within the reservoir were multiplied by estimated and field observed sediment thicknesses to attain a best guess sediment volume. In channel estimates included re-occupying stream channel cross sections established before the fire. Once volumes were calculated, other erosion processes of the Bagley sedimentation study, such as surface soil erosion were combined to estimate the total fire and storm sediment budget for the Squaw Creek watershed. The LiDAR-based measurement workflows can be easily applied to other sediment budget studies using one high resolution LiDAR dataset.

Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2014

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2016-01-01

This Technical Publication (TP) represents an extension of previous work concerning the tropical cyclone activity in the North Atlantic basin during the weather satellite era, 1960-2014, in particular, that of an article published in The Journal of the Alabama Academy of Science. With the launch of the TIROS-1 polar-orbiting satellite in April 1960, a new era of global weather observation and monitoring began. Prior to this, the conditions of the North Atlantic basin were determined only from ship reports, island reports, and long-range aircraft reconnaissance. Consequently, storms that formed far from land, away from shipping lanes, and beyond the reach of aircraft possibly could be missed altogether, thereby leading to an underestimate of the true number of tropical cyclones forming in the basin. Additionally, new analysis techniques have come into use which sometimes has led to the inclusion of one or more storms at the end of a nominal hurricane season that otherwise would not have been included. In this TP, examined are the yearly (or seasonal) and 10-year moving average (10-year moving average) values of the (1) first storm day (FSD), last storm day (LSD), and length of season (LOS); (2) frequencies of tropical cyclones (by class); (3) average peak 1-minute sustained wind speed () and average lowest pressure (); (4) average genesis location in terms of north latitudinal () and west longitudinal () positions; (5) sum and average power dissipation index (); (6) sum and average accumulated cyclone energy (); (7) sum and average number of storm days (); (8) sum of the number of hurricane days (NHD) and number of major hurricane days (NMHD); (9) net tropical cyclone activity index (NTCA); (10) largest individual storm (LIS) PWS, LP, PDI, ACE, NSD, NHD, NMHD; and (11) number of category 4 and 5 hurricanes (N4/5). Also examined are the December-May (D-M) and June-November (J-N) averages and 10-year moving average values of several climatic factors, including the (1) oceanic Nino index (); (2) Atlantic multi-decadal oscillation () index; (3) Atlantic meridional mode () index; (4) global land-ocean temperature index (); and (5) quasi-biennial oscillation () index. Lastly, the associational aspects (using both linear and nonparametric statistical tests) between selected tropical cyclone parameters and the climatic factors are examined based on their 10-year moving average trend values.

Calibration of GOES-VISSR, visible-band satellite data and its application to the analysis of a dust storm at Owens Lake, California

USGS Publications Warehouse

MacKinnon, D.J.; Chavez, P.S.; Fraser, R. S.; Niemeyer, T.C.; Gillette, Dale A.

1996-01-01

As part of a joint Russian/American dust-storm experiment, GOES-VISSR (Geostationary Operational Environmental Satellite, Visible-Infrared Spin-Scan Radiometer), data from a visible-band satellite image of a large dust storm emanating from Owens Lake, California were acquired on March 10 and 11, 1993. The satellite data were calibrated to targets of known ground reflectance factors and processed with radiative transfer techniques to yield aerosol (dust) optical depth at those stages of the dust storm when concurrent ground-based measurements of optical depth were made. Calibration of the satellite data is crucial for comparing surficial changes in remotely sensed data acquired over a period of time from the same area and for determining accurate concentrations of atmospheric aerosols using radiative transfer techniques. The calibration procedure forces the distribution of visible-band, DN (digital number) values, acquired on July 1, 1992, at 1731 GMT from the GOES-VISSR sensor over a large test area, to match the distribution of visible-band, DN values concurrently acquired from a Landsat MSS (Multispectral Scanner) sensor over the same test area; the Landsat MSS DN values were directly associated with reflectance factors measured from ground targets. The calibrated GOES-VISSR data for July 1, 1992, were then used to calibrate other GOES-VISSR data acquired on March 10 and 11, 1993, during the dust storm. Uncertainties in location of ground targets, bi-directional reflectance and atmospheric attenuation contribute an error of approximately ??0.02 in the satellite-inferred ground reflectance factors. On March 11 at 1031 PST the satellite-received radiances during the peak of the storm were 3 times larger than predicted by our radiative transfer model for a pure clay dust plume of infinite optical depth. This result supported ground-based measurements that the plume at that time was composed primarily of large salt grains, probably sodium sulfate, which could not be properly characterized in our radiative transfer model. Further, the satellite data showed that the salt fell out of the plume within 35 km from the source. Finer-grained, clay dust was observed to extend beyond the salt-laden plume and was the major component of the dust plume after 1131 PST, when erosion of the salt crust on Owens Lake ceased. By 1331 and 1401 PST satellite-inferred, optical depths compared favorably with measurements concurrently acquired at the ground. Uncertainties in bi-directional reflectance, atmospheric attenuation, and locating ground points in the satellite data manifest errors between the inferred and measured optical depths in the range of 20 to 50%; these errors would be much greater without the calibration of the GOES-VISSR data. Changes in satellite-inferred reflectance factors over the lake bed during the course of the storm showed that 76 km2 of the surface was disrupted during the March 11 storm, suggesting as much as 76 ?? 103 m3 of crustal material were displaced for each millimeter of several estimated to have been moved during the storm; an unknown fraction of the displaced material was suspended. The satellite data also showed dust fallout on mountain snowfields. Whereas fallout may have removed most of the salt, satellite data acquired at 1631 PST, when the plume had a large brightness contrast with the ground, showed that it covered over 2500 km2 and contained at least 1.6 ?? 109 g of sediment. For such a small source area, the dust represents a substantial contribution to the regional and global load of aerosols.

Development of a Geomagnetic Storm Correction to the International Reference Ionosphere E-Region Electron Densities Using TIMED/SABER Observations

NASA Technical Reports Server (NTRS)

Mertens, C. J.; Xu, X.; Fernandez, J. R.; Bilitza, D.; Russell, J. M., III; Mlynczak, M. G.

2009-01-01

Auroral infrared emission observed from the TIMED/SABER broadband 4.3 micron channel is used to develop an empirical geomagnetic storm correction to the International Reference Ionosphere (IRI) E-region electron densities. The observation-based proxy used to develop the storm model is SABER-derived NO+(v) 4.3 micron volume emission rates (VER). A correction factor is defined as the ratio of storm-time NO+(v) 4.3 micron VER to a quiet-time climatological averaged NO+(v) 4.3 micron VER, which is linearly fit to available geomagnetic activity indices. The initial version of the E-region storm model, called STORM-E, is most applicable within the auroral oval region. The STORM-E predictions of E-region electron densities are compared to incoherent scatter radar electron density measurements during the Halloween 2003 storm events. Future STORM-E updates will extend the model outside the auroral oval.

Root architecture and wind-firmness of mature Pinus pinaster.

PubMed

Danjon, Frédéric; Fourcaud, Thierry; Bert, Didier

2005-11-01

This study aims to link three-dimensional coarse root architecture to tree stability in mature timber trees with an average of 1-m rooting depth. Undamaged and uprooted trees were sampled in a stand damaged by a storm. Root architecture was measured by three-dimensional (3-D) digitizing. The distribution of root volume by root type and in wind-oriented sectors was analysed. Mature Pinus pinaster root systems were organized in a rigid 'cage' composed of a taproot, the zone of rapid taper of horizontal surface roots and numerous sinkers and deep roots, imprisoning a large mass of soil and guyed by long horizontal surface roots. Key compartments for stability exhibited strong selective leeward or windward reinforcement. Uprooted trees showed a lower cage volume, a larger proportion of oblique and intermediate depth horizontal roots and less wind-oriented root reinforcement. Pinus pinaster stability on moderately deep soils is optimized through a typical rooting pattern and a considerable structural adaptation to the prevailing wind and soil profile.

An Estimate of North Atlantic Basin Tropical Cyclone Activity for 2008

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2008-01-01

The statistics of North Atlantic basin tropical cyclones for the interval 1945-2007 are examined and estimates are given for the frequencies of occurrence of the number of tropical cyclones, number of hurricanes, number of major hurricanes, number of category 4/5 hurricanes, and number of U.S. land-falling hurricanes for the 2008 hurricane season. Also examined are the variations of peak wind speed, average peak wind speed per storm, lowest pressure, average lowest pressure per storm, recurrence rate and duration of extreme events (El Nino and La Nina), the variation of 10-yr moving averages of parametric first differences, and the association of decadal averages of frequencies of occurrence of North Atlantic basin tropical cyclones against decadal averages of Armagh Observatory, Northern Ireland, annual mean temperature (found to be extremely important for number of tropical cyclones and number of hurricanes). Because the 2008 hurricane season seems destined to be one that is non-El Nino-related and is a post-1995 season, estimates of the frequencies of occurrence for the various subsets of storms should be above long-term averages.

Exploring Statistical Characterizations of Morphologic Change and Variability: Fire Island, New York

NASA Astrophysics Data System (ADS)

Lentz, E. E.; Hapke, C. J.

2012-12-01

A comprehensive understanding of coastal barrier behavior requires high-resolution observations that capture a wide range of morphological changes occurring over a range of spatial and temporal scales. Fire Island National Seashore, located along the coast of Long Island, New York, is a well studied barrier island coast where understanding how morphological changes contribute to barrier island vulnerability have important implications for coastal land management. Previous work has shown that morphologic differences in eastern and western reaches are attributable to the underlying geology and variations sediment transport in the system. In this study, we further explore western and eastern differences and variability with lidar-derived topographic surfaces to provide a unique and comprehensive investigation of dune-beach change at Fire Island, New York. Continuous topographic surfaces generated from 12 lidar surveys collected between 1998 and 2011 are used to examine the three-dimensional variability over a range of time periods over the 50 km long island. Because surveys were collected over a range of seasons and in response to a number of storm events, we explore morphologic configurations reflecting the seasonality, post-storm configuration, and replenishment response to the system through the generation of a representative or average surface. These averaged surfaces provide the context for what would be an expected or typical coastal configuration under certain conditions, and through comparison with an individual event, can be used to derive an event-specific spatial-change signature. To investigate anthropogenic influences, differences in morphology between a survey collected after a substantial beach replenishment project and a typical fair-weather configuration averaged from six surveys are determined. Storm response variations are also explored by assessing differences between Tropical Storm Irene (2011), Nor'Ida (2009), and a typical post-storm configuration averaged from five post-storm surveys. In addition to averaged surfaces, surveys are combined to generate a new raster surface reflecting cell by cell standard deviations over a defined period. Standard deviation surfaces are generated to highlight 1) where areas of highest and lowest morphologic variation are located over the entire period, and 2) whether spatial similarities exist in variability between storm and non-storm morphologies. Results show there are distinct and variable responses in eastern and western reaches attributable to wave climate, profile gradient, and offshore bathymetry, as well as to a general along-coast increase in sediment availability.

Anchor ice, seabed freezing, and sediment dynamics in shallow arctic seas

USGS Publications Warehouse

Reimnitz, E.; Kempema, E.W.; Barnes, P.W.

1987-01-01

Diving investigations confirm previous circumstantial evidence of seafloor freezing and anchor ice accretion during freeze-up storms in the Alaskan Beaufort Sea. These related bottom types were found to be continuous from shore to 2 m depth and spotty to 4.5 m depth. The concretelike nature of frozen bottom, where present, should prohibit sediment transport by any conceivable wave or current regime during the freezing storm. But elsewhere, anchor ice lifts coarse material off the bottom and incorporates it into the ice canopy, thereby leading to significant ice rafting of shallow shelf sediment and likely sediment loss to the deep sea. -from Authors

An empirical probability density distribution of planetary ionosphere storms with geomagnetic precursors

NASA Astrophysics Data System (ADS)

Gulyaeva, Tamara; Stanislawska, Iwona; Arikan, Feza; Arikan, Orhan

The probability of occurrence of the positive and negative planetary ionosphere storms is evaluated using the W index maps produced from Global Ionospheric Maps of Total Electron Content, GIM-TEC, provided by Jet Propulsion Laboratory, and transformed from geographic coordinates to magnetic coordinates frame. The auroral electrojet AE index and the equatorial disturbance storm time Dst index are investigated as precursors of the global ionosphere storm. The superposed epoch analysis is performed for 77 intense storms (Dst≤-100 nT) and 227 moderate storms (-100

Analysis of dust storms observed in Mongolia during 1937-1999

NASA Astrophysics Data System (ADS)

Natsagdorj, L.; Jugder, D.; Chung, Y. S.

Climatology of dust storms in Mongolia is compiled based on observational data of 49 meteorological stations from 1960 to 1999 and compared them with data between 1937 and 1989. Three different maps of the distribution of dust storms, drifting dust and the number of dusty days are presented. The results of the analysis show that the number of days with dust storms is <5 days over the Altai, the Khangai and the Khentei mountainous regions and more than 20-37 days in the Gobi Desert and semi-desert area. The greatest occurrence of drifting dust arises around the Mongol Els area of west Mongolia. The number of dusty days, which is derived from the sum of the number of days with dust storms and drifting dust, is <10 days in the mountainous area and 61-127 days in the Gobi Desert and the Great Lakes hollow of west Mongolia. It is found that 61% of dust storms occur in the spring in Mongolia and a dust storm lasts on average from 3.1 to 6.0 h. About 65.5-91.0% of dust storms occur in daytime and 9.0-34.5% at night. Dust storms occur more frequently in the city region and are accompanied by surface wind speeds usually from 6 to 20 ms -1. Dust storms usually occur when soil and air are dry, and 70% of dust storms occur in dry soil conditions. When dust storms occur, relative humidity averages 20-40% in Mongolia. An important outcome of this study is the trend of dusty days between 1960 and 1999. It shows that the number of dusty days has tripled from the 1960s to 1990s and has decreased since 1990.

Design flood estimation in ungauged basins: probabilistic extension of the design-storm concept

NASA Astrophysics Data System (ADS)

Berk, Mario; Špačková, Olga; Straub, Daniel

2016-04-01

Design flood estimation in ungauged basins is an important hydrological task, which is in engineering practice typically solved with the design storm concept. However, neglecting the uncertainty in the hydrological response of the catchment through the assumption of average-recurrence-interval (ARI) neutrality between rainfall and runoff can lead to flawed design flood estimates. Additionally, selecting a single critical rainfall duration neglects the contribution of other rainfall durations on the probability of extreme flood events. In this study, the design flood problem is approached with concepts from structural reliability that enable a consistent treatment of multiple uncertainties in estimating the design flood. The uncertainty of key model parameters are represented probabilistically and the First-Order Reliability Method (FORM) is used to compute the flood exceedance probability. As an important by-product, the FORM analysis provides the most likely parameter combination to lead to a flood with a certain exceedance probability; i.e. it enables one to find representative scenarios for e.g., a 100 year or a 1000 year flood. Possible different rainfall durations are incorporated by formulating the event of a given design flood as a series system. The method is directly applicable in practice, since for the description of the rainfall depth-duration characteristics, the same inputs as for the classical design storm methods are needed, which are commonly provided by meteorological services. The proposed methodology is applied to a case study of Trauchgauer Ach catchment in Bavaria, SCS Curve Number (CN) and Unit hydrograph models are used for modeling the hydrological process. The results indicate, in accordance with past experience, that the traditional design storm concept underestimates design floods.

Hurricane Katrina storm surge distribution and field observations on the Mississippi Barrier Islands

NASA Astrophysics Data System (ADS)

Fritz, Hermann M.; Blount, Chris; Sokoloski, Robert; Singleton, Justin; Fuggle, Andrew; McAdoo, Brian G.; Moore, Andrew; Grass, Chad; Tate, Banks

2007-08-01

Hurricane Katrina (23-30 August 2005) struck low-lying coastal plains particularly vulnerable to storm surge flooding. Maximum storm surges, overland flow depths, and inundation distances were measured along the Gulf Coast of Florida, Alabama, Mississippi and Louisiana. The vehicle based survey was complemented by inspections with the reconnaissance boat along the Gulf Coast and the Mississippi Barrier Islands. The storm surge peaked to the East of Katrina's path exceeding 10 meters in several locations along the Mississippi coastline. The storm surge measurements show that the lower floors of specially designed buildings were damaged by the surge of seawater and associated wave action, while the upper floors sustained minimal wind damage. Furthermore, the storm surge measurements along New Orleans's Lake shore indicate that the 17th Street Canal levee failed prior to overtopping. The land loss on the barrier islands resulted in an increased vulnerability of the US Gulf Coast to future hurricane storm surges.

Application of spatial Poisson process models to air mass thunderstorm rainfall

NASA Technical Reports Server (NTRS)

Eagleson, P. S.; Fennessy, N. M.; Wang, Qinliang; Rodriguez-Iturbe, I.

1987-01-01

Eight years of summer storm rainfall observations from 93 stations in and around the 154 sq km Walnut Gulch catchment of the Agricultural Research Service, U.S. Department of Agriculture, in Arizona are processed to yield the total station depths of 428 storms. Statistical analysis of these random fields yields the first two moments, the spatial correlation and variance functions, and the spatial distribution of total rainfall for each storm. The absolute and relative worth of three Poisson models are evaluated by comparing their prediction of the spatial distribution of storm rainfall with observations from the second half of the sample. The effect of interstorm parameter variation is examined.

Properties of a Martian local dust storm in Atlantis Chaos from OMEGA/MEX data

NASA Astrophysics Data System (ADS)

Oliva, F.; Geminale, A.; D'Aversa, E.; Altieri, F.; Bellucci, G.; Carrozzo, F. G.; Sindoni, G.; Grassi, D.

2018-01-01

In this study we present the analysis of the dust properties of a local storm imaged in the Atlantis Chaos region on Mars by the OMEGA imaging spectrometer on March 2nd, 2005. We use the radiative transfer model MITRA to study the dust properties at solar wavelengths between 0.5 μm and 2.5 μm and infer the connection between the local storm dynamics and the topography. We retrieve maps of effective grain radius (reff), optical depth at 9.3 μm (τ9.3) and top altitude (ta) of the dust layer. Our results show that large particles (reff = 1.6 μm) are gathered in the centre of the storm (lat = 33.5° S; lon = 183.5° W), where the optical depth is maximum (τ9.3 > 7.0) and the top altitude exceeds 18 km. Outside the storm, we obtain τ9.3<0.2, in agreement with the estimates derived from global climate models (GCM). We speculate that a low thermal inertia region at the western border of Atlantis Chaos is a possible source of the dust storm. Moreover, we find evidence that topography plays a role in confining the local storm in Atlantis Chaos. The vertical wind component from the GCM does not provide any hint for the triggering of dust lifting. On the other hand, the combination of the horizontal and vertical wind profiles suggests that the dust, once lifted, is pushed eastward and then downward and gets confined within the north-east ridge of Atlantis Chaos. From our results, the thickness of the dust layer collapsed on the surface ranges from about 1 μm at the storm boundaries up to more than 100 μm at its centre. We verify that a layer of dust thicker than 1 μm, deposited on the surface, can prevent the detection of mafic absorption features. However, such features are still present in OMEGA data of Atlantis Chaos registered after the storm. Hence, we deduce that, once the storm is over, the dust deposited on an area larger than the one where it has been observed.

Assessing the Robustness of Green Infrastructure under Stochastic Design Storms and Climate Change Scenarios

NASA Astrophysics Data System (ADS)

Chui, T. F. M.; Yang, Y.

2017-12-01

Green infrastructures (GI) have been widely used to mitigate flood risk, improve surface water quality, and to restore predevelopment hydrologic regimes. Commonly-used GI include, bioretention system, porous pavement and green roof, etc. They are normally sized to fulfil different design criteria (e.g. providing certain storage depths, limiting peak surface flow rates) that are formulated for current climate conditions. While GI commonly have long lifespan, the sensitivity of their performance to climate change is however unclear. This study first proposes a method to formulate suitable design criteria to meet different management interests (e.g. different levels of first flush reduction and peak flow reduction). Then typical designs of GI are proposed. In addition, a high resolution stochastic design storm generator using copulas and random cascade model is developed, which is calibrated using recorded rainfall time series. Then, few climate change scenarios are generated by varying the duration and depth of design storms, and changing the parameters of the calibrated storm generator. Finally, the performance of GI with typical designs under the random synthesized design storms are then assessed using numerical modeling. The robustness of the designs is obtained by the comparing their performance in the future scenarios to the current one. This study overall examines the robustness of the current GI design criteria under uncertain future climate conditions, demonstrating whether current GI design criteria should be modified to account for climate change.

Shifting Pacific storm tracks as stressors to ecosystems of western North America.

PubMed

Dannenberg, Matthew P; Wise, Erika K

2017-11-01

Much of the precipitation delivered to western North America arrives during the cool season via midlatitude Pacific storm tracks, which may experience future shifts in response to climate change. Here, we assess the sensitivity of the hydroclimate and ecosystems of western North America to the latitudinal position of cool-season Pacific storm tracks. We calculated correlations between storm track variability and three hydroclimatic variables: gridded cool-season standardized precipitation-evapotranspiration index, April snow water equivalent, and water year streamflow from a network of USGS stream gauges. To assess how historical storm track variability affected ecosystem processes, we derived forest growth estimates from a large network of tree-ring widths and land surface phenology and wildfire estimates from remote sensing. From 1980 to 2014, cool-season storm tracks entered western North America between approximately 41°N and 53°N. Cool-season moisture supply and snowpack responded strongly to storm track position, with positive correlations to storm track latitude in eastern Alaska and northwestern Canada but negative correlations in the northwestern U.S. Ecosystems of the western United States were greener and more productive following winters with south-shifted storm tracks, while Canadian ecosystems were greener in years when the cool-season storm track was shifted to the north. On average, larger areas of the northwestern United States were burned by moderate to high severity wildfires when storm tracks were displaced north, and the average burn area per fire also tended to be higher in years with north-shifted storm tracks. These results suggest that projected shifts of Pacific storm tracks over the 21st century would likely alter hydroclimatic and ecological regimes in western North America, particularly in the northwestern United States, where moisture supply and ecosystem processes are highly sensitive to the position of cool-season storm tracks. © 2017 John Wiley & Sons Ltd.

Impact of kalbaishakhi storms on adult mosquito populations in Kolkata (Calcutta), India.

PubMed

Pramanik, M K; Raut, S K

2003-01-01

The effect of kalbaishakhi storms on the adult mosquito populations of Kolkata (Calcutta), India was studied in 2000-2001. It is revealed that the density of mosquitoes was reduced, on average by 59.6 and 10%, during the first and second 24 h after each kalbaishakhi storms, respectively. Copyright 2002 Elsevier Science B.V.

Hourly storm characteristics along the U.S. West Coast: Role of atmospheric rivers in extreme precipitation

USGS Publications Warehouse

Lamjiri, Maryam A.; Dettinger, Michael; Ralph, F. Martin; Guan, B.

2017-01-01

Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation totals. Despite generally lower hourly intensities, precipitation totals along the U.S. West Coast (USWC) are comparable to those in southeast U.S. (SEUS). Storm durations, more so than hourly intensities, strongly modulate precipitation-total variability over the USWC, where the correlation coefficients between storm durations and storm totals range from 0.7 to 0.9. Atmospheric rivers (ARs) contribute 30–50% of annual precipitation on the USWC and make such large contributions to extreme storms that 60–100% of the most extreme storms, i.e., storms with precipitation-total return intervals longer than 2 years, are associated with ARs. These extreme storm totals are more strongly tied to storm durations than to storm hourly or average intensities, emphasizing the importance of AR persistence to extreme storms on the USWC.

The Value of Wetlands in Protecting Southeast Louisiana from Hurricane Storm Surges

PubMed Central

Barbier, Edward B.; Georgiou, Ioannis Y.; Enchelmeyer, Brian; Reed, Denise J.

2013-01-01

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively. PMID:23536815

The value of wetlands in protecting southeast louisiana from hurricane storm surges.

PubMed

Barbier, Edward B; Georgiou, Ioannis Y; Enchelmeyer, Brian; Reed, Denise J

2013-01-01

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.

RELATIONSHIPs among Geomagnetic storms, interplanetary shocks, magnetic clouds, and SUNSPOT NUMBER during 1995-2012

NASA Astrophysics Data System (ADS)

Berdichevsky, D. B.; Lepping, R. P.; Wu, C. C.

2015-12-01

During 1995-2012 Wind recorded 168 magnetic clouds (MCs), 197 magnetic cloud-like structures (MCLs), and 358 interplanetary (IP) shocks. Ninety four MCs and 56 MCLs had upstream shock waves. The following features are found: (i) Averages of solar wind speed, interplanetary magnetic field (IMF), duration (<Δt>), strength of Bzmin, and intensity of the associated geomagnetic storm/activity (Dstmin) for MCs with upstream shock waves (MCSHOCK) are higher (or stronger) than those averages for the MCs without upstream shock waves (MCNO-SHOCK). (ii) The <Δt> of MCSHOCK events (≈19.6 hr) is 9% longer than that for MCNO-SHOCK events (≈17.9 hr). (iii) For the MCSHOCK events, the average duration of the sheath (<ΔtSHEATH>) is 12.1 hrs. These findings could be very useful for space weather predictions, i.e. IP shocks driven by MCs are expected to arrive at Wind (or at 1 AU) about ~12 hours ahead of the front of the MCs on average. (iv) The occurrence frequency of IP shocks is well associated with sunspot number (SSN). The average intensity of geomagnetic storms measured by for MCSHOCK and MCNOSHOCK events is -102 and -31 nT, respectively. The is -78, -70, and -35 nT for the 358 IP shocks, 168 MCs, and 197 MCLs, respectively. These results imply that IP shocks, when they occur with MCs/MCLs, must play an important role in the strength of geomagnetic storms. We speculate as to why this is so. Yearly occurrence frequencies of MCSHOCK and IP shocks are well correlated with solar activity (e.g., SSN). Choosing the right Dstmin estimating formula for predicting the intensity of MC-associated geomagnetic storms is crucial for space weather predictions.

Positive cloud-to-ground lightning flashes in severe storms

NASA Technical Reports Server (NTRS)

Rust, W. D.; Macgorman, D. R.; Arnold, R. T.

1981-01-01

The occurrence of cloud-to-ground flashes that effectively lower positive charge to earth (+CG flash) over flat terrain has been documented in the mature stage of severe thunderstorms. Of the 31 documented +CG flashes, most had only one return stroke. Zero-to-peak rise times for the strokes averaged 7 microsec. The +CG flashes averaged 520 ms in duration, with 25 percent lasting more than 800 ms. Many of these had field changes suggestive of continuing current. Positive flashes have been observed to emanate from several regions of severe storms: high on the back of the main storm tower, through the wall cloud, and from the downshear anvil. Visually most of these positive flashes have emanated from high in the storm, and acoustic mapping of two shows thunder sources to a height of about 15 km.

Integration of coastal inundation modeling from storm tides to individual waves

NASA Astrophysics Data System (ADS)

Li, Ning; Roeber, Volker; Yamazaki, Yoshiki; Heitmann, Troy W.; Bai, Yefei; Cheung, Kwok Fai

2014-11-01

Modeling of storm-induced coastal inundation has primarily focused on the surge generated by atmospheric pressure and surface winds with phase-averaged effects of the waves as setup. Through an interoperable model package, we investigate the role of phase-resolving wave processes in simulation of coastal flood hazards. A spectral ocean wave model describes generation and propagation of storm waves from deep to intermediate water, while a non-hydrostatic storm-tide model has the option to couple with a spectral coastal wave model for computation of phase-averaged processes in a near-shore region. The ocean wave and storm-tide models can alternatively provide the wave spectrum and the surface elevation as the boundary and initial conditions for a nested Boussinesq model. Additional surface-gradient terms in the Boussinesq equations maintain the quasi-steady, non-uniform storm tide for modeling of phase-resolving surf and swash-zone processes as well as combined tide, surge, and wave inundation. The two nesting schemes are demonstrated through a case study of Hurricane Iniki, which made landfall on the Hawaiian Island of Kauai in 1992. With input from a parametric hurricane model and global reanalysis and tidal datasets, the two approaches produce comparable significant wave heights and phase-averaged surface elevations in the surf zone. The nesting of the Boussinesq model provides a seamless approach to augment the inundation due to the individual waves in matching the recorded debris line along the coast.

FREE-WATER DEPTH AS A MANAGEMENT TOOL FOR CONSTRUCTED WETLANDS

EPA Science Inventory

Marsh plants in constructed wetlands have shown the capacity to remove unwanted pollutants from storm water runoff. The plants can be established at the site from bare roots. However, plant growth from bare roots can be restricted by the elevated water depths. Using several wa...

Simulated storm surge effects on freshwater coastal wetland soil porewater salinity and extractable ammonium levels: Implications for marsh recovery after storm surge

NASA Astrophysics Data System (ADS)

McKee, M.; White, J. R.; Putnam-Duhon, L. A.

2016-11-01

Coastal wetland systems experience both short-term changes in salinity, such as those caused by wind-driven tides and storm surge, and long-term shifts caused by sea level rise. Salinity increases associated with storm surge are known to have significant effects on soil porewater chemistry, but there is little research on the effect of flooding length on salt penetration depth into coastal marsh soils. A simulated storm surge was imposed on intact soil columns collected from a non-vegetated mudflat and a vegetated marsh site in the Wax Lake Delta, LA. Triplicate intact cores were continuously exposed to a 35 salinity water column (practical salinity scale) for 1, 2, and 4 weeks and destructively sampled in order to measure porewater salinity and extractable NH4sbnd N at two cm depth intervals. Salinity was significantly higher in the top 8 cm for both the marsh and mudflat cores after one week of flooding. After four weeks of flooding, salinity was significantly higher in marsh and mudflat cores compared to the control (no salinity) cores throughout the profile for both sites. Extractable ammonium levels increased significantly in the marsh cores throughout the experiment, but there was only a marginally (p < 0.1) significant increase seen in the mudflat cores. Results indicate that porewater salinity levels can become significantly elevated within a coastal marsh soil in just one week. This vertical intrusion of salt can potentially negatively impact macrophytes and associated microbial communities for significantly longer term post-storm surge.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Eugene; Pierce, Julia; Mahat, Vinod

This project is a part of the Regional Resiliency Assessment Program, led by the Department of Homeland Security, to address flooding hazards of regional significance for Portland, Maine. The pilot study was performed by Argonne National Laboratory to identify differences in spatial rainfall distributions between the radar-derived and rain-gauge rainfall datasets and to evaluate their impacts on urban flooding. The flooding impact analysis utilized a high-resolution 2-dimensional (2-D) hydrodynamic model (15 ft by 15 ft) incorporating the buildings, streets, stream channels, hydraulic structures, an existing city storm drain system, and assuming a storm surge along the coast coincident with amore » heavy rainfall event. Two historical storm events from April 16, 2007, and September 29, 2015, were selected for evaluation. The radar-derived rainfall data at a 200-m resolution provide spatially-varied rainfall patterns with a wide range of intensities for each event. The resultant maximum flood depth using data from a single rain gauge within the study area could be off (either under- or over-estimated) by more than 10% in the 2007 storm and more than 60% in the 2015 storm compared to the radar-derived rainfall data. The model results also suggest that the inundation area with a flow depth at or greater than 0.5 ft could reach 11% (2007 storm) and 17% (2015 storm) of the total study area, respectively. The lowland areas within the neighborhoods of North Deering, East Deering, East and West Baysides and northeastern Parkside, appear to be more vulnerable to the flood hazard in both storm events. The high-resolution 2-D hydrodynamic model with high-resolution radar-derived rainfall data provides an excellent tool for detailed urban flood analysis and vulnerability assessment. The model developed in this study could be potentially used to evaluate any proposed mitigation measures and optimize their effects in the future for Portland, ME.« less

Monitoring subsurface hydrologic response for precipitation-induced shallow landsliding in the San Francisco Bay area, California, USA

USGS Publications Warehouse

Collins, Brian D.; Stock, Jonathan; Weber, Lisa C.; Whitman, K.; Knepprath, N.

2012-01-01

Intense winter storms in the San Francisco Bay area (SFBA) of California, USA often trigger shallow landslides. Some of these landslides mobilize into potentially hazardous debris flows. A growing body of research indicates that rainfall intensity-duration thresholds are insufficient for accurate prediction of landslide occurrence. In response, we have begun long-term monitoring of the hydrologic response of land-slide-prone hillslopes to rainfall in several areas of the SFBA. Each monitoring site is equipped with sensors for measuring soil moisture content and piezometric pressure at several soil depths along with a rain gauge connected to a cell phone or satellite telemetered data logger. The data are transmitted in near-real-time, providing the ability to monitor hydrologic conditions before, during, and after storms. Results are guiding the establishment of both antecedent and storm-specific rainfall and moisture content thresholds which must be achieved before landslide-causative positive pore water pressures are generated. Although widespread shallow landsliding has not yet occurred since the deployment of the monitoring sites, several isolated land-slides have been observed in the area of monitoring. The landslides occurred during a period when positive pore water pressures were measured as a result of intense rainfall that followed higher-than-average season precipitation totals. Continued monitoring and analysis will further guide the establishment of more general-ized thresholds for different regions of the SFBA and contribute to the development and calibration of physi-cally-based predictive models.

State of Arctic Sea Ice North of Svalbard during N-ICE2015

NASA Astrophysics Data System (ADS)

Rösel, Anja; King, Jennifer; Gerland, Sebastian

2016-04-01

The N-ICE2015 cruise, led by the Norwegian Polar Institute, was a drift experiment with the research vessel R/V Lance from January to June 2015, where the ship started the drift North of Svalbard at 83°14.45' N, 21°31.41' E. The drift was repeated as soon as the vessel drifted free. Altogether, 4 ice stations where installed and the complex ocean-sea ice-atmosphere system was studied with an interdisciplinary Approach. During the N-ICE2015 cruise, extensive ice thickness and snow depth measurements were performed during both, winter and summer conditions. Total ice and snow thickness was measured with ground-based and airborne electromagnetic instruments; snow depth was measured with a GPS snow depth probe. Additionally, ice mass balance and snow buoys were deployed. Snow and ice thickness measurements were performed on repeated transects to quantify the ice growth or loss as well as the snow accumulation and melt rate. Additionally, we collected independent values on surveys to determine the general ice thickness distribution. Average snow depths of 32 cm on first year ice, and 52 cm on multi-year ice were measured in January, the mean snow depth on all ice types even increased until end of March to 49 cm. The average total ice and snow thickness in winter conditions was 1.92 m. During winter we found a small growth rate on multi-year ice of about 15 cm in 2 months, due to above-average snow depths and some extraordinary storm events that came along with mild temperatures. In contrast thereto, we also were able to study new ice formation and thin ice on newly formed leads. In summer conditions an enormous melt rate, mainly driven by a warm Atlantic water inflow in the marginal ice zone, was observed during two ice stations with melt rates of up to 20 cm per 24 hours. To reinforce the local measurements around the ship and to confirm their significance on a larger scale, we compare them to airborne thickness measurements and classified SAR-satellite scenes. The here presented data set is important for understanding the ocean-ice-atmosphere interactions, for calculating energy fluxes, and biogeochemical processes.

Recent Responses of Western North American Forests and Hydroclimate to Pacific Storm Track Position and Intensity

NASA Astrophysics Data System (ADS)

Dannenberg, M. P.; Wise, E.

2017-12-01

Much of the precipitation delivered to western North America arrives during the October to March cool season via midlatitude Pacific storm tracks, which may shift in the future due to climate change. Using historical climate, tree-ring, and remote sensing data, we assessed the sensitivity of western North American hydroclimate and ecosystems to the position and intensity of cool-season Pacific storm tracks. From 1980-2014, mean annual cool-season storm tracks entered western North America between approximately 41°N to 53°N, with substantial interannual variability in both the position and intensity of the storm tracks. We examined relationships between storm tracks and two hydroclimatic variables: the cool-season standardized precipitation-evapotranspiration index and April snow water equivalent. We also assessed how historical storm track variability affected ecosystems using forest growth estimates from a large tree-ring network as well as land surface phenology and wildfire estimates from AVHRR and Landsat, respectively. Cool-season moisture supply and snowpack responded strongly to storm track position, with positive correlations to storm track latitude in eastern Alaska and northwestern Canada but negative correlations in the northwestern U.S. These hydroclimatic impacts were largely driven by the latitudinal position of storm tracks during the "shoulder" seasons (i.e., autumn and early spring). Ecosystems of the western U.S. tended to be greener and more productive following winters with south-shifted storm tracks, while Canadian ecosystems were greener in years when the cool-season storm track was shifted to the north. On average, larger areas of the northwestern U.S. were burned by moderate to high severity wildfires when storm tracks were displaced north, and the average burn area per fire also tended to be higher in years with north-shifted storm tracks. Assuming that these historical relationships continue to hold under future climate scenarios, our results suggest that projected long-term shifts of Pacific storm tracks over the 21st century would likely alter hydroclimatic and ecological regimes in western North America, particularly in the northwestern U.S., where moisture supply and ecosystem processes are highly sensitive to the position of cool-season storm tracks.

The Effect of Asian Dust Aerosols on Cloud Properties and Radiative Forcing from MODIS and CERES

NASA Technical Reports Server (NTRS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2005-01-01

The effects of dust storms on cloud properties and radiative forcing are analyzed over northwestern China from April 2001 to June 2004 using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of the cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. The humidity differences are larger in the dusty region than in the dust-free region, and may be caused by removal of moisture by wet dust precipitation. Due to changes in cloud microphysics, the instantaneous net radiative forcing is reduced from -71.2 W/m2 for dust contaminated clouds to -182.7 W/m2 for dust-free clouds. The reduced cooling effects of dusts may lead to a net warming of 1 W/m2, which, if confirmed, would be the strongest aerosol forcing during later winter and early spring dust storm seasons over the studied region.

The cascade from local to global dust storms on Mars: Temporal and spatial thresholds on thermal and dynamical feedback

NASA Astrophysics Data System (ADS)

Toigo, Anthony D.; Richardson, Mark I.; Wang, Huiqun; Guzewich, Scott D.; Newman, Claire E.

2018-03-01

We use the MarsWRF general circulation model to examine the temporal and spatial response of the atmosphere to idealized local and regional dust storm radiative heating. The ability of storms to modify the atmosphere away from the location of dust heating is a likely prerequisite for dynamical feedbacks that aid the growth of storms beyond the local scale, while the ability of storms to modify the atmosphere after the cessation of dust radiative heating is potentially important in preconditioning the atmosphere prior to large scale storms. Experiments were conducted over a range of static, prescribed storm sizes, durations, optical depth strengths, locations, and vertical extents of dust heating. Our results show that for typical sizes (order 105 km2) and durations (1-10 sols) of local dust storms, modification of the atmosphere is less than the typical variability of the unperturbed (storm-free) state. Even if imposed on regional storm length scales (order 106 km2), a 1-sol duration storm similarly does not significantly modify the background atmosphere. Only when imposed for 10 sols does a regional dust storm create a significant impact on the background atmosphere, allowing for the possibility of self-induced dynamical storm growth. These results suggest a prototype for how the subjective observational categorization of storms may be related to objective dynamical growth feedbacks that only become available to storms after they achieve a threshold size and duration, or if they grow into an atmosphere preconditioned by a prior large and sustained storm.

Development of a depth-integrated sample arm (DISA) to reduce solids stratification bias in stormwater sampling

USGS Publications Warehouse

Selbig, William R.; ,; Roger T. Bannerman,

2011-01-01

A new depth-integrated sample arm (DISA) was developed to improve the representation of solids in stormwater, both organic and inorganic, by collecting a water quality sample from multiple points in the water column. Data from this study demonstrate the idea of vertical stratification of solids in storm sewer runoff. Concentrations of suspended sediment in runoff were statistically greater using a fixed rather than multipoint collection system. Median suspended sediment concentrations measured at the fixed location (near the pipe invert) were approximately double those collected using the DISA. In general, concentrations and size distributions of suspended sediment decreased with increasing vertical distance from the storm sewer invert. Coarser particles tended to dominate the distribution of solids near the storm sewer invert as discharge increased. In contrast to concentration and particle size, organic material, to some extent, was distributed homogenously throughout the water column, likely the result of its low specific density, which allows for thorough mixing in less turbulent water.

Development of a depth-integrated sample arm to reduce solids stratification bias in stormwater sampling.

PubMed

Selbig, William R; Bannerman, Roger T

2011-04-01

A new depth-integrated sample arm (DISA) was developed to improve the representation of solids in stormwater, both organic and inorganic, by collecting a water quality sample from multiple points in the water column. Data from this study demonstrate the idea of vertical stratification of solids in storm sewer runoff. Concentrations of suspended sediment in runoff were statistically greater using a fixed rather than multipoint collection system. Median suspended sediment concentrations measured at the fixed location (near the pipe invert) were approximately double those collected using the DISA. In general, concentrations and size distributions of suspended sediment decreased with increasing vertical distance from the storm sewer invert. Coarser particles tended to dominate the distribution of solids near the storm sewer invert as discharge increased. In contrast to concentration and particle size, organic material, to some extent, was distributed homogenously throughout the water column, likely the result of its low specific density, which allows for thorough mixing in less turbulent water.

Development of a depth-integrated sample arm to reduce solids stratification bias in stormwater sampling

USGS Publications Warehouse

Selbig, W.R.; Bannerman, R.T.

2011-01-01

A new depth-integrated sample arm (DISA) was developed to improve the representation of solids in stormwater, both organic and inorganic, by collecting a water quality sample from multiple points in the water column. Data from this study demonstrate the idea of vertical stratification of solids in storm sewer runoff. Concentrations of suspended sediment in runoff were statistically greater using a fixed rather than multipoint collection system. Median suspended sediment concentrations measured at the fixed location (near the pipe invert) were approximately double those collected using the DISA. In general, concentrations and size distributions of suspended sediment decreased with increasing vertical distance from the storm sewer invert. Coarser particles tended to dominate the distribution of solids near the storm sewer invert as discharge increased. In contrast to concentration and particle size, organic material, to some extent, was distributed homogenously throughout the water column, likely the result of its low specific density, which allows for thorough mixing in less turbulent water. ?? 2010 Publishing Technology.

Hurricane Rita and the destruction of Holly Beach, Louisiana: Why the chenier plain is vulnerable to storms

USGS Publications Warehouse

Sallenger, A.H.; Wright, C.W.; Doran, K.; Guy, K.; Morgan, K.

2009-01-01

Hurricane Rita devastated gulf-front communities along the western Louisiana coast in 2005. LIDAR (light detection and ranging) topographic surveys and aerial photography collected before and after the storm showed the loss of every structure within the community of Holly Beach. Average shoreline change along western Louisiana's 140-km-long impacted shore was -23.3 ?? 30.1 m of erosion, although shoreline change in Holly Beach was substantially less, and erosion was not pervasive where the structures were lost. Before the storm, peak elevations of the dunes, or berms in the absence of dunes, along the impacted shore averaged 1.6 m. The storm surge, which reached 3.5 m just east of Holly Beach, completely inundated the beach systems along the impacted western Louisiana shore. The high surge potential and low land elevations make this coast extremely vulnerable to hurricanes. In fact, most of the western Louisiana shore impacted by Rita will be completely inundated by the storm surge of a worst-case Saffi r-Simpson category 1 hurricane. All of this shore will be inundated by worst-case category 2-5 storms. ?? 2009 The Geological Society of America.

Depth-area-duration characteristics of storm rainfall in Texas using Multi-Sensor Precipitation Estimates

NASA Astrophysics Data System (ADS)

McEnery, J. A.; Jitkajornwanich, K.

2012-12-01

This presentation will describe the methodology and overall system development by which a benchmark dataset of precipitation information has been used to characterize the depth-area-duration relations in heavy rain storms occurring over regions of Texas. Over the past two years project investigators along with the National Weather Service (NWS) West Gulf River Forecast Center (WGRFC) have developed and operated a gateway data system to ingest, store, and disseminate NWS multi-sensor precipitation estimates (MPE). As a pilot project of the Integrated Water Resources Science and Services (IWRSS) initiative, this testbed uses a Standard Query Language (SQL) server to maintain a full archive of current and historic MPE values within the WGRFC service area. These time series values are made available for public access as web services in the standard WaterML format. Having this volume of information maintained in a comprehensive database now allows the use of relational analysis capabilities within SQL to leverage these multi-sensor precipitation values and produce a valuable derivative product. The area of focus for this study is North Texas and will utilize values that originated from the West Gulf River Forecast Center (WGRFC); one of three River Forecast Centers currently represented in the holdings of this data system. Over the past two decades, NEXRAD radar has dramatically improved the ability to record rainfall. The resulting hourly MPE values, distributed over an approximate 4 km by 4 km grid, are considered by the NWS to be the "best estimate" of rainfall. The data server provides an accepted standard interface for internet access to the largest time-series dataset of NEXRAD based MPE values ever assembled. An automated script has been written to search and extract storms over the 18 year period of record from the contents of this massive historical precipitation database. Not only can it extract site-specific storms, but also duration-specific storms and storms separated by user defined inter-event periods. A separate storm database has been created to store the selected output. By storing output within tables in a separate database, we can make use of powerful SQL capabilities to perform flexible pattern analysis. Previous efforts have made use of historic data from limited clusters of irregularly spaced physical gauges. Spatial extent of the observational network has been a limiting factor. The relatively dense distribution of MPE provides a virtual mesh of observations stretched over the landscape. This work combines a unique hydrologic data resource with programming and database analysis to characterize storm depth-area-duration relationships.

Quantification and regionalization of groundwater recharge in South-Central Kansas: Integrating field characterization, statistical analysis, and GIS

USGS Publications Warehouse

Sophocleous, M.

2000-01-01

A practical methodology for recharge characterization was developed based on several years of field-oriented research at 10 sites in the Great Bend Prairie of south-central Kansas. This methodology combines the soil-water budget on a storm-by-storm year-round basis with the resulting watertable rises. The estimated 1985-1992 average annual recharge was less than 50mm/year with a range from 15 mm/year (during the 1998 drought) to 178 mm/year (during the 1993 flood year). Most of this recharge occurs during the spring months. To regionalize these site-specific estimates, an additional methodology based on multiple (forward) regression analysis combined with classification and GIS overlay analyses was developed and implemented. The multiple regression analysis showed that the most influential variables were, in order of decreasing importance, total annual precipitation, average maximum springtime soil-profile water storage, average shallowest springtime depth to watertable, and average springtime precipitation rate. Therefore, four GIS (ARC/INFO) data "layers" or coverages were constructed for the study region based on these four variables, and each such coverage was classified into the same number of data classes to avoid biasing the results. The normalized regression coefficients were employed to weigh the class rankings of each recharge-affecting variable. This approach resulted in recharge zonations that agreed well with the site recharge estimates. During the "Great Flood of 1993," when rainfall totals exceeded normal levels by -200% in the northern portion of the study region, the developed regionalization methodology was tested against such extreme conditions, and proved to be both practical, based on readily available or easily measurable data, and robust. It was concluded that the combination of multiple regression and GIS overlay analyses is a powerful and practical approach to regionalizing small samples of recharge estimates.

Dust Storm Signatures in Global Ionosphere Map of GPS Total Electron Content

NASA Astrophysics Data System (ADS)

Lin, Fang-Tse; Shih, Ai-Ling; Liu, Jann-Yenq; Kuo, Cheng-Ling; Lin, Tang-Huang; Lien, Wei-Hung

2016-04-01

In this paper both MODIS data and GIM (global ionosphere map) TEC (total electron content) as well as numerical simulations are used to study ionospheric dust storm effects in May 2008. The aerosol optical depth (AOD) and the LTT (latitude-time-TEC) along the Sahara longitude simultaneously reach their maximum values on 28 May 2008. The LLT (latitude-longitude-TEC) map specifically and significantly increases over the Sahara region on 28 May 2008. The simulation suggests that the dust storm may change the atmospheric conductivity, which in turn modifies the GIM TEC over the Sahara area.

Environmental Education: Non-point Source Pollution

EPA Pesticide Factsheets

This activity is designed to demonstrate to students what an average storm drain collects during a rainfall event and how the water from storm drains can impact the water quality and aquatic environments of local streams, rivers, and bays.

Ion radial diffusion in an electrostatic impulse model for stormtime ring current formation

NASA Technical Reports Server (NTRS)

Chen, Margaret W.; Schulz, Michael; Lyons, Larry R.; Gorney, David J.

1992-01-01

Two refinements to the quasi-linear theory of ion radial diffusion are proposed and examined analytically with simulations of particle trajectories. The resonance-broadening correction by Dungey (1965) is applied to the quasi-linear diffusion theory by Faelthammar (1965) for an individual model storm. Quasi-linear theory is then applied to the mean diffusion coefficients resulting from simulations of particle trajectories in 20 model storms. The correction for drift-resonance broadening results in quasi-linear diffusion coefficients with discrepancies from the corresponding simulated values that are reduced by a factor of about 3. Further reductions in the discrepancies are noted following the averaging of the quasi-linear diffusion coefficients, the simulated coefficients, and the resonance-broadened coefficients for the 20 storms. Quasi-linear theory provides good descriptions of particle transport for a single storm but performs even better in conjunction with the present ensemble-averaging.

Subtropical Dust Storms and Downslope Wind Events

NASA Astrophysics Data System (ADS)

Pokharel, Ashok Kumar; Kaplan, Michael L.; Fiedler, Stephanie

2017-10-01

We performed detailed mesoscale observational analyses and Weather Research and Forecasting (WRF) model simulations to study the terrain-induced downslope winds that generated dust-emitting winds at the beginning of three strong subtropical dust storms in three distinctly different regions of North Africa and the Arabian Peninsula. We revisit the Harmattan dust storm of 2 March 2004, the Saudi dust storm of 9 March 2009, and the Bodélé Depression dust storm of 8 December 2011 and use high-resolution WRF modeling to assess the dynamical processes during the onset of the storms in more depth. Our results highlight the generation of terrain-induced downslope winds in response to the transition of the atmospheric flow from a subcritical to supercritical state in all three cases. These events precede the unbalanced adjustment processes in the lee of the mountain ranges that produced larger-scale dust aerosol mobilization and transport. We see that only the higher-resolution data sets can resolve the mesoscale processes, which are mainly responsible for creating strong low-level terrain-induced downslope winds leading to the initial dust storms.

Analysis of Wave Predictions from the Coastal Model Test Bed using Operationally Estimated Bathymetry

NASA Astrophysics Data System (ADS)

Bak, S.; Smith, J. M.; Hesser, T.; Bryant, M. A.

2016-12-01

Near-coast wave models are generally validated with relatively small data sets that focus on analytical solutions, specialized experiments, or intense storms. Prior studies have compiled testbeds that include a few dozen experiments or storms to validate models (e.g., Ris et al. 2002), but few examples exist that allow for continued model evaluation in the nearshore and surf-zone in near-realtime. The limited nature of these validation sets is driven by a lack of high spatial and temporal resolution in-situ wave measurements and the difficulty in maintaining these instruments on the active profile over long periods of time. The US Army Corps of Engineers Field Research Facility (FRF) has initiated a Coastal Model Test-Bed (CMTB), which is an automated system that continually validates wave models (with morphological and circulation models to follow) utilizing the rich data set of oceanographic and bathymetric measurements collected at the FRF. The FRF's cross-shore wave array provides wave measurements along a cross-shore profile from 26 m of water depth to the shoreline, utilizing various instruments including wave-rider buoys, AWACs, aquadopps, pressure gauges, and a dune-mounted lidar (Brodie et al. 2015). This work uses the CMTB to evaluate the performance of a phase-averaged numerical wave model, STWAVE (Smith 2007, Massey et al. 2011) over the course of a year at the FRF in Duck, NC. Additionally, from the BathyDuck Experiment in October 2015, the CMTB was used to determine the impact of applying the depth boundary condition for the model from monthly acoustic bathymetric surveys in comparison to hourly estimates using a video-based inversion method (e.g., cBathy, Holman et al. 2013). The modeled wave parameters using both bathymetric boundary conditions are evaluated using the FRF's cross-shore wave array and two additional cross-shore arrays of wave measurements in 2 to 4 m water depth from BathyDuck in Fall, 2015.

Observations of Martian ice clouds by the Mars Global Surveyor Thermal Emission Spectrometer: The first Martian year

NASA Astrophysics Data System (ADS)

Pearl, John C.; Smith, Michael D.; Conrath, Barney J.; Bandfield, Joshua L.; Christensen, Philip R.

2001-06-01

Successful operation of the Mars Global Surveyor spacecraft, beginning in September 1997 (Ls=184°), has permitted extensive observations over more than a Martian year. Initially, thin (normal optical depth <0.06 at 825 cm-1) ice clouds and hazes were widespread, showing a distinct latitudinal gradient. With the onset of a regional dust storm at Ls=224°, ice clouds vanished in the southern hemisphere, to reappear gradually after the decay of the storm. The zonally averaged cloud opacities show little difference between the beginning and end of the first Martian year. A broad low-latitude cloud belt with considerable longitudinal structure was present in early northern summer. Apparently characteristic of the northern summer season, it vanished between Ls=140° and 150°. The latitudinal extent of this feature is apparently controlled by the ascending branch of the Hadley circulation. The most opaque clouds (optical depth ~0.6) were found above the summits of major volcanic features; these showed spatial structure possibly associated with wave activity. Variety among low-lying late morning clouds suggests localized differences in circulation and microclimates. Limb observations showed extensive optically thin (optical depth <0.04) stratiform clouds at altitudes up to 55 km. Considerable latitude and altitude variations were evident in ice clouds in early northern spring (Ls=25°) near 30 km, thin clouds extended from just north of the equator to ~45°N, nearly to the north polar vortex. A water ice haze was present in the north polar night (Ls=30°) at altitudes up to 40 km. Because little dust was present this probably provided heterogeneous nucleation sites for the formation of CO2 clouds and snowfall at altitudes below ~20 km, where atmospheric temperatures dropped to the CO2 condensation point. The relatively invariant spectral shape of the water ice cloud feature over space and time indicates that ice particle radii are generally between 1 and 4 μm.

Effects of Geomagnetic Storms on the Postsunset Vertical Plasma Drift in the Equatorial Ionosphere

NASA Astrophysics Data System (ADS)

Huang, Chao-Song

2018-05-01

It has been observed that geomagnetic storms cause suppression of the occurrence of equatorial spread F or plasma bubbles in the evening sector. In this study, we use ion drift data measured by the Communication/Navigation Outage Forecasting System satellite over 6 years (2008-2014) to derive the dependence of the vertical ion drift at the prereversal enhancement peak on the strength of magnetic storms (the Dst index). It is found that the average vertical ion drift does not change much for Dst in the range between 0 and -60 nT but decreases approximately linearly with the increasing magnitude of Dst for Dst < -60 nT. The net decrease in the average vertical ion drift is 30 m/s when Dst changes from -60 to -90 nT. This result is derived when the ion drift data during the storm main phase are excluded, so the decrease of the vertical ion drift is caused by storm time disturbance dynamo. A possible interpretation of this phenomenon is that geomagnetic activity must be strong enough (e.g., Dst < -60 nT) so disturbance winds can reach the equatorial region and change plasma drifts there. The storm time disturbance dynamo becomes dominant in the equatorial ionospheric dynamics near the end of the storm main phase, 4.7 hr after the storm onset. The postsunset vertical ion drift is significantly decreased during the early stage of the storm recovery phase but becomes almost fully recovered when Dst increases close to -60 nT.

The potential use of storm water and effluent from a constructed wetland for re-vegetating a degraded pyrite trail in Queen Elizabeth National Park, Uganda

NASA Astrophysics Data System (ADS)

Osaliya, R.; Kansiime, F.; Oryem-Origa, H.; Kateyo, E.

During the operation of the Kilembe Mines (copper mining) a cobaltiferous stockpile was constructed, which began to erode after the closure of the mines in the early 1970s. The erosion of the pyrite stockpile resulted in a large acid trail all the way to Lake George (a Ramsar site). The acid trail contaminated a large area of Queen Elizabeth National Park (QENP) resulting in the death of most of the shallow-rooted vegetation. Processes and conditions created by storm water and effluent from a constructed wetland were assessed for vegetation regeneration in the degraded QENP pyrite trail. Cynodon dactylon, Imperata cylindrica and Hyparrhenia filipendula dominated the regeneration zone (RZ) where storm water and effluent from a constructed wetland was flowing; and the adjacent unpolluted area (UP) with importance value indices of 186.4 and 83.3 respectively. Typha latifolia and C. dactylon formed two distinct vegetation sub-zones within the RZ with the former inhabiting areas with a higher water table. Soil pH was significantly higher in the RZ, followed by UP and bare pyrite trail (BPT) at both 0-15 cm and 16-30 cm depths. Soil electrical conductivity was not significantly different in the RZ and BPT but significantly higher than that in UP for both depths. For 0-15 cm depth, RZ had significantly higher concentrations of copper than BPT and UP which had similar concentrations. Still at this depth (0-15 cm), the unpolluted area had significantly higher concentrations of total phosphorus and total nitrogen than the regeneration zone and the bare pyrite trail which had similar concentrations. The RZ dominated by Typha had significantly higher concentrations of TP and TN compared to the RZ dominated by Cynodon. The concentrations of NH 4-N were significantly lower in Typha regeneration zone than in CRZ at 0-15 cm depth but similar at 16-30 cm depth. At 16-30 cm depth, concentrations of copper were significantly higher in the regeneration zone followed by the bare pyrite trail and the unpolluted zone. The concentration of lead in the regeneration zone and bare pyrite trail were similar but significantly higher in the unpolluted zone. Concentrations of TP and TN were significantly higher in unpolluted zone, followed by regeneration zone and bare pyrite trail. Storm water and effluent from a constructed wetland enhanced the revegetation process by modifying soil pH, making plant growth nutrients available and by providing a steady supply of moisture necessary for plant growth. T. latifolia and C. dactylon which seem to have tolerance of high concentrations of metals were the dominant species in the regeneration zone. If storm water and effluent supply continues, the aforementioned vegetation will colonize the pyrite trail and will eventually protect QENP and Lake George from metal contamination.

The Electric Storm of November 1882

NASA Astrophysics Data System (ADS)

Love, Jeffrey J.

2018-01-01

In November 1882, an intense magnetic storm related to a large sunspot group caused widespread interference to telegraph and telephone systems and provided spectacular and unusual auroral displays. The (ring current) storm time disturbance index for this storm reached maximum -Dst ≈ 386 nT, comparable to Halloween storm of 29-31 October 2003, but from 17 to 20 November the aa midlatitude geomagnetic disturbance index averaged 214.25 nT, the highest 4 day level of disturbance since the beginning of aa index in 1868. This storm contributed to scientists' understanding of the reality of solar-terrestrial interaction. Past occurrences of magnetic storms, like that of November 1882, can inform modern evaluations of the deleterious effects that a magnetic superstorm might have on technological systems of importance to society.

Identifying long term empirical relationships between storm characteristics and episodic groundwater recharge

USGS Publications Warehouse

Tashie, Arik; Mirus, Benjamin B.; Pavelsky, Tamlin

2016-01-01

Shallow aquifers are an important source of water resources and provide base flow to streams; yet actual rates of groundwater recharge are difficult to estimate. While climate change is predicted to increase the frequency and magnitude of extreme precipitation events, the resulting impact on groundwater recharge remains poorly understood. We quantify empirical relations between precipitation characteristics and episodic groundwater recharge for a wide variety of geographic and land use types across North Carolina. We extract storm duration, magnitude, average rate, and hourly weighted intensity from long-term precipitation records over periods of 12–35 years at 10 locations. Using time series of water table fluctuations from nearby monitoring wells, we estimate relative recharge to precipitation ratios (RPR) to identify statistical trends. Increased RPR correlates with increased storm duration, whereas RPR decreases with increasing magnitude, average rate, and intensity of precipitation. Agricultural and urban areas exhibit the greatest decrease in RPR due to increasing storm magnitude, average rate, and intensity, while naturally vegetated areas exhibit a larger increase in RPR with increased storm duration. Though RPR is generally higher during the winter than the summer, this seasonal effect is magnified in the Appalachian and Piedmont regions. These statistical trends provide valuable insights into the likely consequences of climate and land use change for water resources in subtropical climates. If, as predicted, growing seasons lengthen and the intensity of storms increases with a warming climate, decreased recharge in Appalachia, the Piedmont, and rapidly growing urban areas of the American Southeast could further limit groundwater availability.

Severe Weather Guide - Mediterranean Ports. 7. Marseille

DTIC Science & Technology

1988-03-01

the afternoon. Upper—level westerlies and the associated storm track is moved northward during summer, so extratropical cyclones and associated...autumn as the extratropical storm track moves southward. Precipitation amount is the highest of the year, with an average of 3 inches (76 mm) for the...18 SUBJECT TERMS (Continue on reverse if necessary and identify by block number) Storm haven Mediterranean meteorology Marseille port

Cloudsat tropical cyclone database

NASA Astrophysics Data System (ADS)

Tourville, Natalie D.

CloudSat (CS), the first 94 GHz spaceborne cloud profiling radar (CPR), launched in 2006 to study the vertical distribution of clouds. Not only are CS observations revealing inner vertical cloud details of water and ice globally but CS overpasses of tropical cyclones (TC's) are providing a new and exciting opportunity to study the vertical structure of these storm systems. CS TC observations are providing first time vertical views of TC's and demonstrate a unique way to observe TC structure remotely from space. Since December 2009, CS has intersected every globally named TC (within 1000 km of storm center) for a total of 5,278 unique overpasses of tropical systems (disturbance, tropical depression, tropical storm and hurricane/typhoon/cyclone (HTC)). In conjunction with the Naval Research Laboratory (NRL), each CS TC overpass is processed into a data file containing observational data from the afternoon constellation of satellites (A-TRAIN), Navy's Operational Global Atmospheric Prediction System Model (NOGAPS), European Center for Medium range Weather Forecasting (ECMWF) model and best track storm data. This study will describe the components and statistics of the CS TC database, present case studies of CS TC overpasses with complementary A-TRAIN observations and compare average reflectivity stratifications of TC's across different atmospheric regimes (wind shear, SST, latitude, maximum wind speed and basin). Average reflectivity stratifications reveal that characteristics in each basin vary from year to year and are dependent upon eye overpasses of HTC strength storms and ENSO phase. West Pacific (WPAC) basin storms are generally larger in size (horizontally and vertically) and have greater values of reflectivity at a predefined height than all other basins. Storm structure at higher latitudes expands horizontally. Higher vertical wind shear (≥ 9.5 m/s) reduces cloud top height (CTH) and the intensity of precipitation cores, especially in HTC strength storms. Average zero and ten dBZ height thresholds confirm WPAC storms loft precipitation sized particles higher into the atmosphere than in other basins. Two CS eye overpasses (32 hours apart) of a weakening Typhoon Nida in 2009 reveal the collapse of precipitation cores, warm core anomaly and upper tropospheric ice water content (IWC) under steady moderate shear conditions.

Bathymetric Contour Maps for Lakes Surveyed in Iowa in 2006

USGS Publications Warehouse

Linhart, S.M.; Lund, K.D.

2008-01-01

The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources, conducted bathymetric surveys on two lakes in Iowa during 2006 (Little Storm Lake and Silver Lake). The surveys were conducted to provide the Iowa Department of Natural Resources with information for the development of total maximum daily load limits, particularly for estimating sediment load and deposition rates. The bathymetric surveys can provide a baseline for future work on sediment loads and deposition rates for these lakes. Both of the lakes surveyed in 2006 are natural lakes. For Silver Lake, bathymetric data were collected using boat-mounted, differential global positioning system, echo depth-sounding equipment, and computer software. For Little Storm Lake, because of its shallow nature, bathymetric data were collected using manual depth measurements. Data were processed with commercial hydrographic software and exported into a geographic information system for mapping and calculating area and volume. Lake volumes were estimated to be 7,547,000 cubic feet (173 acre-feet) at Little Storm Lake and 126,724,000 cubic feet (2,910 acre-feet) at Silver Lake. Surface areas were estimated to be 4,110,000 square feet (94 acres) at Little Storm Lake and 27,957,000 square feet (640 acres) at Silver Lake.

Possible influences of Asian dust aerosols on cloud properties and radiative forcing observed from MODIS and CERES

NASA Astrophysics Data System (ADS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2006-03-01

The effects of dust storms on cloud properties and Radiative Forcing (RF) are analyzed over Northwestern China from April 2001 to June 2004 using data collected by the MODerate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. Due to changes in cloud microphysics, the instantaneous net RF is increased from -161.6 W/m2 for dust-free clouds to -118.6 W/m2 for dust-contaminated clouds.

Solar radio continuum storms and a breathing magnetic field model

NASA Technical Reports Server (NTRS)

1975-01-01

Radio noise continuum emissions observed in metric and decametric wave frequencies are, in general, associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. These continuum emission sources, often called type I storm sources, are often associated with type III burst storm activity from metric to hectometric wave frequencies. This storm activity is, therefore, closely connected with the development of these continuum emission sources. It is shown that the S-component emission in microwave frequencies generally precedes, by several days, the emission of these noise continuum storms of lower frequencies. In order for these storms to develop, the growth of sunspot groups into complex types is very important in addition to the increase of the average magnetic field intensity and area of these groups. After giving a review on the theory of these noise continuum storm emissions, a model is briefly considered to explain the relation of the emissions to the storms.

Storm flow export of metolachlor from a coastal plain watershed.

PubMed

Watts, D W; Novak, J M; Johnson, M H; Stone, K C

2000-03-01

During an 18-month (1994-1995) survey of the surface water in an Atlantic Coastal Plain watershed, metolachlor was most frequently detected during storm flow events. Therefore, a sampling procedure, focused on storm flow, was implemented in June of 1996. During 1996, three tropical cyclones made landfall within 150 km of the watershed. These storms, as well as several summer thunderstorms, produced six distinct storm flow events within the watershed. Metolachlor was detected leaving the watershed during each event. In early September, Hurricane Fran produced the largest storm flow event and accounted for the majority of the metolachlor exports. During the storm event triggered by Hurricane Fran, the highest daily average flow (7.5 m2 s-1) and highest concentration (5.1 micrograms L-1) ever measured at the watershed outlet were recorded. Storm flow exports leaving the watershed represented 0.1 g ha-1 or about 0.04% of active ingredient applied.

Coastal flood inundation monitoring with Satellite C-band and L-band Synthetic Aperture Radar data

USGS Publications Warehouse

Ramsey, Elijah W.; Rangoonwala, Amina; Bannister, Terri

2013-01-01

Satellite Synthetic Aperture Radar (SAR) was evaluated as a method to operationally monitor the occurrence and distribution of storm- and tidal-related flooding of spatially extensive coastal marshes within the north-central Gulf of Mexico. Maps representing the occurrence of marsh surface inundation were created from available Advanced Land Observation Satellite (ALOS) Phased Array type L-Band SAR (PALSAR) (L-band) (21 scenes with HH polarizations in Wide Beam [100 m]) data and Environmental Satellite (ENVISAT) Advanced SAR (ASAR) (C-band) data (24 scenes with VV and HH polarizations in Wide Swath [150 m]) during 2006-2009 covering 500 km of the Louisiana coastal zone. Mapping was primarily based on a decrease in backscatter between reference and target scenes, and as an extension of previous studies, the flood inundation mapping performance was assessed by the degree of correspondence between inundation mapping and inland water levels. Both PALSAR- and ASAR-based mapping at times were based on suboptimal reference scenes; however, ASAR performance seemed more sensitive to reference-scene quality and other types of scene variability. Related to water depth, PALSAR and ASAR mapping accuracies tended to be lower when water depths were shallow and increased as water levels decreased below or increased above the ground surface, but this pattern was more pronounced with ASAR. Overall, PALSAR-based inundation accuracies averaged 84% (n = 160), while ASAR-based mapping accuracies averaged 62% (n = 245).

Studies of humid continental haze during SPACE

NASA Technical Reports Server (NTRS)

Bowdle, D. A.; Greene, W. A.

1985-01-01

A concept for a solar radiometer network to provide supporting data during the Satellite Preciptiation and Cloud Experiment (SPACE) was developed. Each of the 9 prime and 10 supplementary SPACE ground sites will be equipped with an upward pointing global solar pyranometer. About half of the sites will also be equipped with upward pointing diffuse (shade ring) solar pyranometers, and a downward pointing global albedo pyranometer. These radiometers will be used to monitor the spatial and temporal variability of solar insolation and haze optical depth. The insolation data will ultimately be input to numerical models of the pre-storm and near-storm boundary layer. The optical depth data will be compared with simultaneous measurements from airborne and satellite-based passive visible radiometers and airborne lidars.

Are Eyewall Replacement Cycles Governed Largely by Axisymmetric Balance Dynamics?

DTIC Science & Technology

2015-01-01

this viewpoint, the inward contraction of an eyewall is a mechanism driven by differential diabatic heating, and friction plays an un- important role...shows the azimuthally averaged kinematic and thermodynamical structure of the RAMS simulation, along with the corresponding averaged diabatic heating rate...structure of the storm, with the 360-K isotherm sloping upward from 9 to 13.5km between the center of the storm and 150-km radius. The mean diabatic heating

Temporal and spatial variability of rainfall pH

Treesearch

Richard G. Semonin

1977-01-01

The distribution of average rainwater pH over an area of 1,800 km² containing 81 collectors was determined from 25 storm events. The areal average of the data was pH 4.9, with a range of values from 4.3 to 6.8. A single storm event was studied to determine the change of pH as a function of time. The initial rain was pH 7.1, decreasing to 4.1. An excellent...

Decadal Trends of Atlantic Basin Tropical Cyclones (1950-1999)

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2001-01-01

Ten-year moving averages of the seasonal rates for 'named storms,' tropical storms, hurricanes, and major (or intense) hurricanes in the Atlantic basin suggest that the present epoch is one of enhanced activity, marked by seasonal rates typically equal to or above respective long-term median rates. As an example, the 10-year moving average of the seasonal rates for named storms is now higher than for any previous year over the past 50 years, measuring 10.65 in 1994, or 2.65 units higher than its median rate of 8. Also, the 10-year moving average for tropical storms has more than doubled, from 2.15 in 1955 to 4.60 in 1992, with 16 of the past 20 years having a seasonal rate of three or more (the median rate). For hurricanes and major hurricanes, their respective 10-year moving averages turned upward, rising above long-term median rates (5.5 and 2, respectively) in 1992, a response to the abrupt increase in seasonal rates that occurred in 1995. Taken together, the outlook for future hurricane seasons is for all categories of Atlantic basin tropical cyclones to have seasonal rates at levels equal to or above long-term median rates, especially during non-El Nino-related seasons. Only during El Nino-related seasons does it appear likely that seasonal rates might be slightly diminished.

Simulation and analysis of synoptic scale dust storms over the Arabian Peninsula

NASA Astrophysics Data System (ADS)

Beegum, S. Naseema; Gherboudj, Imen; Chaouch, Naira; Temimi, Marouane; Ghedira, Hosni

2018-01-01

Dust storms are among the most severe environmental problems in arid and semi-arid regions of the world. The predictability of seven dust events, viz. D1: April 2-4, 2014; D2: February 23-24, 2015; D3: April 1-3, 2015; D4: March 26-28, 2016; D5: August 3-5, 2016; D6: March 13-14, 2017 and D7:March 19-21, 2017, are investigated over the Arabian Peninsula using a regionally adapted chemistry transport model CHIMERE coupled with the Weather Research and Forecast (WRF) model. The hourly forecast products of particulate matter concentrations (PM10) and aerosol optical depths (AOD) are compared against both satellite-based (MSG/SEVRI RGB dust, MODIS Deep Blue Aerosol Optical Depth: DB-AOD, Ozone Monitoring Instrument observed UV Aerosol Absorption Index: OMI-AI) and ground-based (AERONET AOD) remote sensing products. The spatial pattern and the time series of the simulations show good agreement with the observations in terms of the dust intensity as well as the spatiotemporal distribution. The causative mechanisms of these dust events are identified by the concurrent analyses of the meteorological data. From these seven storms, five are associated with synoptic scale meteorological processes, such as prefrontal storms (D1 and D7), postfrontal storms of short (D2), and long (D3) duration types, and a summer shamal storm (D6). However, the storms D4 and D6 are partly associated with mesoscale convective type dust episodes known as haboobs. The socio-economic impacts of the dust events have been assessed by estimating the horizontal visibility, air quality index (AQI), and the dust deposition flux (DDF) from the forecasted dust concentrations. During the extreme dust events, the horizontal visibility drops to near-zero values co-occurred withhazardous levels of AQI and extremely high dust deposition flux (250 μg cm- 2 day- 1).

Assessment of coastal flood risk in a changing climate along the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Bilskie, M. V.; Hagen, S. C.; Passeri, D. L.; Alizad, K.

2014-12-01

Coastal regions around the world are susceptible to a variety of natural disasters causing extreme inundation. It is anticipated that the vulnerability of coastal cities will increase due to the effects of climate change, and in particular sea level rise (SLR). We have developed a novel framework to construct a physics-based storm surge model that includes projections of coastal floodplain dynamics under climate change scenarios. Numerous experiments were conducted and it was concluded that a number of influencing factors, other than SLR, should be included in future assessments of coastal flooding under climate change; e.g., shoreline changes, barrier island morphology, salt marsh migration, and population dynamics. These factors can significantly affect the path, pattern, and magnitude of flooding depths and inundation along the coastline (Bilskie et al., 2014; Passeri et al., 2014). Using these factors, a storm surge model of the northern Gulf of Mexico (NGOM) representing present day conditions is modified to characterize the future outlook of the landscape. This adapted model is then used to assess flood risk in terms of the 100-year floodplain surface under SLR scenarios. A suite of hundreds of synthetic storms, derived by JPM-OS (Joint Probability Method - Optimum Sampling), are filtered to obtain the storms necessary to represent the statistically determined 100-year floodplain. The NGOM storm surge model is applied to simulate the synthetic storms and determine, for each storm, the flooding surface and depth, for four SLR scenarios for the year 2100 as prescribed by Parris et al. (2012). The collection of results facilitate the estimation of water surface elevation vs. frequency curves across the floodplain and the statistically defined 100-year floodplain is extracted. This novel method to assess coastal flooding under climate change can be performed across any coastal region worldwide, and results provide awareness of regions vulnerable to extreme flooding in the future.

The electric storm of November 1882

USGS Publications Warehouse

Love, Jeffrey J.

2018-01-01

In November 1882, an intense magnetic storm related to a large sunspot group caused widespread interference to telegraph and telephone systems and provided spectacular and unusual auroral displays. The (ring current) storm time disturbance index for this storm reached maximum −Dst ≈ 386 nT, comparable to Halloween storm of 29–31 October 2003, but from 17 to 20 November the aa midlatitude geomagnetic disturbance index averaged 214.25 nT, the highest 4 day level of disturbance since the beginning of aa index in 1868. This storm contributed to scientists' understanding of the reality of solar‐terrestrial interaction. Past occurrences of magnetic storms, like that of November 1882, can inform modern evaluations of the deleterious effects that a magnetic superstorm might have on technological systems of importance to society.

Variations in storm response along a microtidal transgressive barrier-island arc

NASA Astrophysics Data System (ADS)

Kahn, J. H.; Roberts, H. H.

1982-10-01

Storm response along the transgressive Chandeleur barrier-island arc southeast of the Mississippi delta plain is variable because of local differences in sediment supply, shoreline orientation and barrier morphology. A study of the morphological impact of Hurricane Frederic (1979) affirmed that tropical storms are the primary agents causing erosion and migration of this barrier arc. Frederic's greatest impact was in the duneless southern Chandeleurs, where sheet-flow overwash caused flattening of the barrier profile, destruction of a strip of marsh 50-100 m wide, and shoreline retreat of approximately 30 m. In contrast, overwash in the northern Chandeleurs was confined between dunes in channels established by previous storms. This channelized overwash breached the northern Chandeleur barriers in nineteen places. As Frederic passed, return flow through these channels transported overwashed sediment back to the nearshore zone. These ebb deposits were a source for longshore drift sediments, which quickly sealed storm channels, reestablishing a coherent northern Chandeleur barrier arc. These storm response patterns may help explain long-term changes in barrier morphology. During an 84-yr period (1885-1969) the southern Chandeleurs decreased 41 % in area, with an average retreat rate of 9.1 m yr -1, compared to a 15% increase in area and an average shoreline retreat rate of 7.2 m yr -1 for the northern Chandeleurs.

Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)

NASA Astrophysics Data System (ADS)

Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

2012-02-01

On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m 3.m - 1 . These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m 3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

Experimental Constraints On Transparency of The 1052;1040;rtian Atmosphere Out of Dust Storm

NASA Astrophysics Data System (ADS)

Korablev, O.; Moroz, V. I.; Rodin, A. V.

In the absence of a dust storm so-called permanent dust haze with = 0.2 in the atmo- sphere of Mars determines its thermal structure, as it has been shown by Gierasch and Goody [1972 JAS 29, 400] and is confirmed by modern Mars GCMs that include dust cycle. Dust loading varies substantially with the season and geographic location, and only the data of mapping instruments are adequate to characterize it. Presently, these are the data of thermal IR instruments, benefiting from being insensitive to condensa- tional clouds: TES/MGS and IRTM/Viking. In calm atmospheric conditions (aphelion season) a typical value of 9-µm optical depth 9 of 0.05-0.15 is observed by these instruments [Smith et al. 2000, 2001 JGR 105, 9539; JGR 106, 23929; Martin and Richardson 1993 JGR 98, 10941]. In order to quantify the typical optical depth of the permanent dust haze, we will discuss, among others, the following two questions: 1) How to agree the above values and reliable measurements from the surface (VL, Pathfinder) which give the typical optical depth (out of dust storms) of = 0.5 from one side, and some ground-based observations (in UV-visible range) that frequently reveal < 0.02 on the other side. 2) What is the relationship between 9 and the visi- ble optical depth? Comparison of IRTM and VL measurements (the only simultaneous observations available so far) suggest vis/9 = 2.5, that contradict to vis/9 = 0.9 that follow from IRIS/Mariner 9 mineralogy model, which is confirmed by recent re- analysis of IRIS data.

Surf Zone Properties and On/Offshore Sediment Transport.

DTIC Science & Technology

1982-06-01

and Random Waves," Proceedings, 14th Coastal Engineering Conference, 1974, pp.558-574. Levi - Civita , T., "Determination Rigoreuse des Ondes...on Beach 2-6 Classification of Normal and Storm Beach 23 Profiles by Dean 2-7 Classification of Normal and Storm Beach 24 Profiles by Author 2-8 Two ...the surface and near bottom, return flow near mid-depth before wave breaking. There were considerable laboratory evidences supporting the two -dimen

Isotopic Variability in Central Valley Precipitation Events

NASA Astrophysics Data System (ADS)

Keene, D.; Sowers, T.; Wagner, A. J.

2017-12-01

Wintertime precipitation in the Sacramento Valley is characterized by two regimes: northerly storms generated by the polar jet stream and southerly storms generated by subtropical atmospheric rivers (ARs). Polar jet stream storms account for the majority of storm activity in the central valley, but the amount of subtropical moisture available for transport tends to increase during El Niño years. However, during the El Niño of 2015-2016, California continued to experience drought conditions with the Sacramento area receiving below average wintertime precipitation. Although the 2016-2017 winter was not an El Niño year, the Sacramento area received more than 190% of its average precipitation from ARs in the opening months of 2017. While this suggests that ARs are a significant part of California's hydrologic cycle independent of El Niño, it has not been established whether these storms have an isotopically distinct signature compared to those generated by the polar jet stream or if their signature covaries with ENSO. To investigate the potential isotopic variability of ARs, rainwater was collected over a period of three years in the Sacramento Valley and the surrounding areas and analyzed for δD and δ18O. Since El Niño is generally considered to cause an increase in the amount of available subtropical moisture delivered to the Sacramento valley, we would expect precipitation during those years to be less depleted than precipitation in non-El Niño years. On average, δD and δ18O values of precipitation during the 2015-2016 winter were not significantly different compared to precipitation from 2016-2017 even though 2016-2017 was dominated by historic amounts of AR rainfall. This suggests that the frequency and intensity of atmospheric river storm events may not be intimately linked with the ENSO cycle.

Interplanetary radio storms. 2: Emission levels and solar wind speed in the range 0.05-0.8 AU

NASA Technical Reports Server (NTRS)

Bougeret, J. L.; Fainberg, J.; Stone, R. G.

1982-01-01

Storms of interplanetary type III radio bursts (IP storms) are commonly observed in the interplanetry medium by the ISEE-3 radio instrument. This instrument has the capability of accurately determining the arrival direction of the radio emission. At each observing frequency, the storm radio sources are tracked as they cross the line-of-sight to the Sun. Usng a simple model, the emission levels are determined at a number of radio frequencies for four separate storms. The IP storm radiation is found to occur in regions of enhanced density at levels of 0.05 to 0.8 AU. The density in these enhancements falls off faster than R(-2). The solar wind speed in the storm region is also measured. The analysis is consistent with steady conditions in the storm region during a few days around the central meridian passage of the storm. The comparison with average in situ density measurements compiled from the HELIOS 1-2 observations favors type III storm burst radio emission at the harmonic of the local plasma frequency.

To what extent can green infrastructure mitigate downstream flooding in a peri-urban catchment?

NASA Astrophysics Data System (ADS)

Schubert, J. E.; Burns, M.; Sanders, B. F.; Flethcher, T.

2016-12-01

In this research, we couple an urban hydrologic model (MUSIC, eWater, AUS) with a fine resolution 2D hydrodynamic model (BreZo, UC Irvine, USA) to test to what extent retrofitting an urban watershed with stormwater control measures (SCMs) can propagate flood management benefits downstream. Our study site is the peri-urban Little Stringybark Creek (LSC) catchment in eastern Melbourne, AUS, with an area of 4.5 km2 and connected impervious area of 9%. Urban development is mainly limited to the upper 2 km2of the catchment. Since 2009 the LSC catchment has been the subject of a large-scale experiment aiming to restore morenatural flow by implementing over 300 SCMs, such as rain tanks and infiltration trenches, resulting in runoff from 50% of connected impervious areas now being intercepted by some form of SCM. For our study we calibrated the hydrologic and hydraulic models based on current catchment conditions, then we developed models representing alternative SCM scenarios including a complete lack of SCMs versus a full implementation of SCMs. Flow in the hydrologic/hydraulic models is forced using a range of synthetic rainfall events with annual exceedance probabilities (AEPs) between 63-1% and durations between 10 min to 24 hr. Metrics of SCM efficacy in changing flood regime include flood depths and extents, flow intensity (m2/s), flood duration, and critical storm duration leading to maximum flood conditions. Results indicate that across the range of AEPs tested and for storm durations equal or less than 3 hours, current SCM conditions reduce downstream flooded area on average by 29%, while a full implementation of SCMs would reduce downstream flooded area on average by 91%. A full implementation of SCMs could also lower maximum flow intensities by 83% on average, reducing damage potential to structures in the flow path and increasing the ability for vehicles to evacuate flooded streets. We also found that for storm durations longer than 3 hours, the SCMs capacity to retain rainfall runoff volumes is much decreased, with a full implementation of SCMs only reducing flooded area by 8% and flow intensity by 5.5%. Therefore additional measures are required for downstream flood hazard mitigation from long duration events.

Physical and Chemical Properties of Seasonal Snow and the Impacts on Albedo in New Hampshire, USA

NASA Astrophysics Data System (ADS)

Adolph, A. C.; Albert, M. R.; Amante, J.; Dibb, J. E.

2014-12-01

Snow albedo is critical to surface energy budgets and thus to the timing of mid-winter and vernal melt events in seasonal snow packs. Timing of these melt events is important in predicting flooding, understanding plant and animal phenology, and the availability of winter recreational activity. The state of New Hampshire experiences large spatial and temporal variability in snow albedo as a result of differences in meteorological conditions, physical snow structure, and chemical impurities in the snow, particularly highly absorptive black carbon (BC) and dust particles. This work focuses on the winters of 2012-2013 and 2013-2014, comparing three intensive study sites. Data collected at these sites include sub-hourly meteorological data, near daily measurements of snow depth, snow density, surface IR temperature, specific surface area (SSA) from contact spectroscopy, and spectrally resolved snow albedo using an ASD FieldSpec4 throughout the winter season. Additionally, snow samples were analyzed for black carbon content and other chemical impurities including Cl-, NO3-, NH4 , K , Na , Mg2+ , Ca2+ and SO42-. For each storm event at the three intensive sites, moisture sources and paths were determined using HYPLIT back trajectory modeling to determine potential sources of black carbon and other impurities in the snow. Storms with terrestrial-based paths across the US Midwest and Canada resulted in higher BC content than storms with ocean-based paths and sources. In addition to the variable storm path between sites and between years, the second year of study was on average 2.5°C colder than the first year, impacting duration of snow cover at each site and the SSA of surface snow which is sensitive to frequency of snow events and relies on cold temperatures to reduce grain metamorphism. Combining an understanding of storm frequency and path with physical and chemical attributes of the snow allows us to investigate snow albedo sensitivities with implications for understanding the impacts of future climate change on snow albedo in the Northeastern US.

Mobility of maerl-siliciclastic mixtures: Impact of waves, currents and storm events

NASA Astrophysics Data System (ADS)

Joshi, Siddhi; Duffy, Garret Patrick; Brown, Colin

2017-04-01

Maerl beds are free-living, non-geniculate coralline algae habitats which form biogenic reefs with high micro-scale complexity supporting a diversity and abundance of rare epifauna and epiflora. These habitats are highly mobile in shallow marine environments where substantial maerl beds co-exist with siliciclastic sediment, exemplified by our study site of Galway Bay. Coupled hydrodynamic-wave-sediment transport models have been used to explore the transport patterns of maerl-siliciclastic sediment during calm summer conditions and severe winter storms. The sediment distribution is strongly influenced by storm waves even in water depths greater than 100 m. Maerl is present at the periphery of wave-induced residual current gyres during storm conditions. A combined wave-current Sediment Mobility Index during storm conditions shows correlation with multibeam backscatter and surficial sediment distribution. A combined wave-current Mobilization Frequency Index during storm conditions acts as a physical surrogate for the presence of maerl-siliciclastic mixtures in Galway Bay. Both indices can provide useful integrated oceanographic and sediment information to complement coupled numerical hydrodynamic, sediment transport and erosion-deposition models.

Pulsing Inertial Oscillation, Supercell Storms, and Surface Mesonetwork Data

NASA Technical Reports Server (NTRS)

Costen, R. C.; Miller, L. J.

1998-01-01

The pulsing inertial oscillation (PIO) model is a nonlinear, time-dependent, translating vortex solution of the inviscid, compressible fluid dynamic equations in the middle troposphere. The translation of this vortex during a pulse is strikingly similar to that of a supercell storm -- a rotating thunderstorm that can generate tornadoes and hail. Two studies were performed to test the hypothesis that some supercell storms are manifestations of a PIO pulse. The first study applied the model to an intense interior draft whose buoyancy was bounded by a temperature excess of +/- 12 K. The peak updraft speed achieved was 41.5 m/ s and the peak Rossby number was 92.9. The study also pointed to an advanced concept for attaining higher values. The second study applied the PIO model to a supercell storm as a whole and succeeded in replicating its bulk properties, such as mesocyclonic circulation, net mass and moisture influxes, and time track. This study also identified a critical feature of the PIO model that could be tested against storm data: The average vertical draft is downward before the turn in the storm track and upward afterwards. In the conventional theory, the average vertical draft is upward from storm inception until dissipation. These differing draft predictions were compared with the best available data, which are surface mesonetwork data. These data were found to support the PIO model. However, surface data alone are not conclusive, and further measurements are warranted.

The Poleward Shift of Storm Tracks Under Climate Change: Tracking Cyclones in CMIP5

NASA Astrophysics Data System (ADS)

Kaspi, Y.; Tamarin, T.

2017-12-01

Extratropical cyclones dominate the distribution of precipitation and wind in the midlatitudes, and therefore their frequency, intensity, and paths have a significant effect on weather and climate. Comprehensive climate models forced by enhanced greenhouse gas emissions suggest that under a climate change scenario, the latitudinal band of storm tracks would shift poleward. While the poleward shift is a robust response across most models, there is currently no consensus on what is the dominant dynamical mechanism. Here we use a Lagrangian approach to study the poleward shift, by employing a storm-tracking algorithm on an ensemble of CMIP5 models forced by increased CO2 emissions. We demonstrate that in addition to a poleward shift in the latitude of storm genesis, associated with the expansion of the Hadley cell, the averaged cyclonic storm also propagates more poleward until it reaches its maximum intensity. A mechanism for enhanced poleward motion of cyclones in a warmer climate is proposed, supported by idealized global warming experiments, and relates the shift to changes in upper level jet and atmospheric water vapour content. Our results imply that under the RCP8.5 climate change scenario, the averaged latitude of peak cyclone intensity shifts poleward by about 1.2○ (1.0○) in the Atlantic (Pacific) storm track in the Northern Hemisphere (NH), and by about 1.6○ in the Southern Hemisphere (SH) storm track. These changes in cyclone tracks can have a significant impact on midlatitude climate.

Storming ahead

NASA Astrophysics Data System (ADS)

Showstack, Randy

Fourteen tropical storms, nine hurricanes, and four intense hurricanes with winds above 111 mph. That's the forecast for hurricane activity in the Atlantic Basin for the upcoming hurricane season which extends from June 1 through November 30, 1999, according to a Colorado State Hurricane Forecast team led by William Gray, professor of atmospheric science. The forecast supports an earlier report by the team.Hurricane activity, said Gray will be similar to 1998—which yielded 14 tropical storms, 10 hurricanes, and 3 intense storms. These numbers are significantly higher than the long-term statistical averages of 9.3, 5.8, and 2.2, annually.

Latitudinal Dependence of the Energy Input into the Mesosphere by High Energy Electrons

NASA Technical Reports Server (NTRS)

Wagner, C. U.; Nikutowski, B.; Ranta, H.

1984-01-01

Night-time ionspheric absorption measurements give the possibility to study the precipitation of high energy electrons into the mesosphere during and after magnetospheric storms. The uniform Finnish riometer network was used together with measurements from Kuhlungsborn and Collm (GDR) to investigate the night-time absorption as a function of latitude (L=6.5 to 2.5) and storm-time for seven storms. The common trends visible in all these events are summarized in a schematic average picture, showing the distribution of increased ionospheric absorption as a function of latitude (L value) and storm-time.

Simulating storm surge inundation and damage potential within complex port facilities

NASA Astrophysics Data System (ADS)

Mawdsley, Robert; French, Jon; Fujiyama, Taku; Achutan, Kamalasudhan

2017-04-01

Storm surge inundation of port facilities can cause damage to critical elements of infrastructure, significantly disrupt port operations and cause downstream impacts on vital supply chains. A tidal surge in December 2013 in the North Sea partly flooded the Port of Immingham, which handles the largest volume of bulk cargo in the UK including major flows of coal and biomass for power generation. This flooding caused damage to port and rail transport infrastructure and disrupted operations for several weeks. This research aims to improve resilience to storm surges using hydrodynamic modelling coupled to an agent-based model of port operations. Using the December 2013 event to validate flood extent, depth and duration, we ran a high resolution hydrodynamic simulation using the open source Telemac 2D finite element code. The underlying Digital Elevation Model (DEM) was derived from Environment Agency LiDAR data, with ground truthing of the flood defences along the port frontage. Major infrastructure and buildings are explicitly resolved with varying degrees of permeability. Telemac2D simulations are run in parallel and take only minutes on a single 16 cpu compute node. Inundation characteristics predicted using Telemac 2D differ from a simple Geographical Information System 'bath-tub' analysis of the DEM based upon horizontal application of the maximum water level across the port topography. The hydrodynamic simulation predicts less extensive flooding and more closely matches observed flood extent. It also provides more precise depth and duration curves. Detailed spatial flood depth and duration maps were generated for a range of tide and surge scenarios coupled to mean sea-level rise projections. These inundation scenarios can then be integrated with critical asset databases and an agent-based model of port operation (MARS) that is capable of simulating storm surge disruption along wider supply chains. Port operators are able to act on information from a particular flood scenario to perform adaptive responses (e.g. pre-emptive relocation of equipment), as well as estimate the likely duration of any disruption to port and supply chain operation. High resolution numerical inundation modelling, coupled to accurate storm surge forecasting and an agent based port operation model, thus has the potential to significantly reduce damage and disruption costs associated with storm surge impacts on port infrastructure and systems.

Development of a CME-associated geomagnetic storm intensity prediction tool

NASA Astrophysics Data System (ADS)

Wu, C. C.; DeHart, J. M.

2015-12-01

From 1995 to 2012, the Wind spacecraft recorded 168 magnetic cloud (MC) events. Among those events, 79 were found to have upstream shock waves and their source locations on the Sun were identified. Using a recipe of interplanetary magnetic field (IMF) Bz initial turning direction after shock (Wu et al., 1996, GRL), it is found that the north-south polarity of 66 (83.5%) out of the 79 events were accurately predicted. These events were tested and further analyzed, reaffirming that the Bz intial turning direction was accurate. The results also indicate that 37 of the 79 MCs originate from the north (of the Sun) averaged a Dst_min of -119 nT, whereas 42 of the MCs originating from the south (of the Sun) averaged -89 nT. In an effort to provide this research to others, a website was built that incorporated various tools and pictures to predict the intensity of the geomagnetic storms. The tool is capable of predicting geomagnetic storms with different ranges of Dst_min (from no-storm to gigantic storms). This work was supported by Naval Research Lab HBCU/MI Internship program and Chief of Naval Research.

Coastal-storm Inundation and Sea-level Rise in New Zealand Scott A. Stephens and Rob Bell

NASA Astrophysics Data System (ADS)

Stephens, S. A.; Bell, R.

2016-12-01

Coastal-storm inundation is a growing problem in New Zealand. It happens occasionally, when the combined forces of weather and sea line up, causing inundation of low-elevation land, coastal erosion, and rivers and stormwater systems to back up causing inland flooding. This becomes a risk where we have placed buildings and infrastructure too close to the coast. Coastal-storm inundation is not a new problem, it has happened historically, but it is becoming more frequent as the sea level continues to rise. From analyses of historic extreme sea-level events, we show how the different sea-level components, such as tide and storm surge, contribute to extreme sea-level and how these components vary around New Zealand. Recent sea-level analyses reveal some large storm surges, bigger than previously reported, and we show the type of weather patterns that drive them, and how this leads to differences in storm surge potential between the east and west coasts. Although large and damaging storm-tides have occurred historically, we show that there is potential for considerably larger elevations to be reached in the "perfect storm", and we estimate the likelihood of such extreme events occurring. Sea-level rise (SLR) will greatly increase the frequency, depth and consequences of coastal-storm inundation in the future. We show an application of a new method to determine the increasing frequency of extreme sea-levels with SLR, one which integrates the extreme tail with regularly-occurring high tides. We present spatial maps of several extreme sea-level threshold exceedance statistics for a case study at Mission Bay, Auckland, New Zealand. The maps show how the local community is likely to face decision points at various SLR thresholds, and we conclude that coastal hazard assessments should ideally use several SLR scenarios and time windows within the next 100 years or more to support the decision-making process for future coastal adaptation and when response options will be needed. In tandem, coastal hazard assessments should also provide information on SLR values linked to expected inundation frequency or depth. This can be linked to plausible timeframes for SLR thresholds to determine when critical decision points for adaptation might be reached, and we show how this might be achieved.

A new methodology for surcharge risk management in urban areas (case study: Gonbad-e-Kavus city).

PubMed

Hooshyaripor, Farhad; Yazdi, Jafar

2017-02-01

This research presents a simulation-optimization model for urban flood mitigation integrating Non-dominated Sorting Genetic Algorithm (NSGA-II) with Storm Water Management Model (SWMM) hydraulic model under a curve number-based hydrologic model of low impact development technologies in Gonbad-e-Kavus, a small city in the north of Iran. In the developed model, the best performance of the system relies on the optimal layout and capacity of retention ponds over the study area in order to reduce surcharge from the manholes underlying a set of storm event loads, while the available investment plays a restricting role. Thus, there is a multi-objective optimization problem with two conflicting objectives solved successfully by NSGA-II to find a set of optimal solutions known as the Pareto front. In order to analyze the results, a new factor, investment priority index (IPI), is defined which shows the risk of surcharging over the network and priority of the mitigation actions. The IPI is calculated using the probability of pond selection for candidate locations and average depth of the ponds in all Pareto front solutions. The IPI can help the decision makers to arrange a long-term progressive plan with the priority of high-risk areas when an optimal solution has been selected.

Calculating sediment discharge from a highway construction site in central Pennsylvania

USGS Publications Warehouse

Reed, L.A.; Ward, J.R.; Wetzel, K.L.

1985-01-01

The Pennsylvania Department of Transportation, the Federal Highway Administration, and the U.S. Geological Survey have cooperated in a study to evaluate two methods of predicting sediment yields during highway construction. Sediment yields were calculated using the Universal Soil Loss and the Younkin Sediment Prediction Equations. Results were compared to the actual measured values, and standard errors and coefficients of correlation were calculated. Sediment discharge from the construction area was determined for storms that occurred during construction of Interstate 81 in a 0.38-square mile basin near Harrisburg, Pennsylvania. Precipitation data tabulated included total rainfall, maximum 30-minute rainfall, kinetic energy, and the erosive index of the precipitation. Highway construction data tabulated included the area disturbed by clearing and grubbing, the area in cuts and fills, the average depths of cuts and fills, the area seeded and mulched, and the area paved. Using the Universal Soil Loss Equation, sediment discharge from the construction area was calculated for storms. The standard error of estimate was 0.40 (about 105 percent), and the coefficient of correlation was 0.79. Sediment discharge from the construction area was also calculated using the Younkin Equation. The standard error of estimate of 0.42 (about 110 percent), and the coefficient of correlation of 0.77 are comparable to those from the Universal Soil Loss Equation.

Precipitation data considerations for evaluating subdaily changes in rainless periods due to climate change

USDA-ARS?s Scientific Manuscript database

Quantifying magnitudes and frequencies of rainless times between storms (TBS), or storm occurrence, is required for generating continuous sequences of precipitation for modeling inputs to small watershed models for conservation studies. Two parameters characterize TBS, minimum TBS (MTBS) and averag...

Time-series variations in CFC and 3H/3He ages in springs discharging from an eogenetic karst aquifer (Invited)

NASA Astrophysics Data System (ADS)

Martin, J. B.; Kurz, M. J.; Khadka, M. B.; Cohen, M. J.

2013-12-01

One of the hallmarks of karst aquifers is rapid mixing between surface water and groundwater, which results in changes in flow and water chemistry at springs. Aquifers with little matrix porosity (telogenetic karst) tend to respond to storm events within days to weeks (e.g., are flashy) while aquifers characterized by elevated matrix porosity (eogenetic karst) may take months or years to respond. This response time is an important control on remediation of storm-derived contaminants as well as the magnitude of water-rock reactions that may result from mixing of surface water and groundwater with different compositions. Responses of flashy springs may be observed through time-series measurements of various solute compositions of the discharge, but response at springs discharging from eogenetic aquifers are difficult to observe because the chemical composition of the recharged storm water may be altered during its residence in the subsurface. For these aquifers, conservative tracers such as chlorofluorocarbon and 3H/3He ratios may provide useful information on the mixing, residence time, and variation in the average age of discharged water. We are testing this hypothesis at six springs discharging from the Floridan Aquifer to the Ichetucknee River in north Florida. Samples were first collected September 3, 2009 during record low flow when the river was discharging 7.2 m3/sec and subsequently after about 400 mm of rain fell over the springshed from June 23 to 26, 2012 during Tropical Storm Debby. Following the storm, samples were collected July 27, 2012 (all six springs) when flow had increased to 10.5 m3/sec. Three of the six springs were sampled during the recession on October 25, 2012 (Q = 10.3 m3/sec), February 14, 2013 (Q = 8.7 m3/sec), and May 16, 2013 (Q = 8.6 m3/sec). CFC dates are available now for all sampling times but 3H/3He dates are only available through October 25, 2012. The two different tracers yield conflicting results with CFC ages generally increasing from the low flow to flood samples while 3H/3He ages decrease in five of the six springs with increasing discharge. The age of the water would be expected to decrease following the storm, suggesting that the CFC data may be contaminated. Assuming the drought discharge is solely groundwater and the measured reduction in the 3H/3He ages originates from mixing old groundwater with zero-aged water from the storm, the fraction of discharging storm water ranged from 4 to 25% of the total discharge. This variation in the fraction of the storm-derived water corresponds to estimated depths of flow paths to the springs based on dissolved oxygen and temperature data. Springs originating from deep flow paths have smaller fractions of storm water. Time-series measurements of ages of water discharging from springs appear to be a useful technique for estimating fractions of storm derived water and possibly flow paths in springs discharging from eogenetic karst aquifers.

Physical aspects of Hurricane Hugo in Puerto Rico

USGS Publications Warehouse

Scatena, F.N.; Larsen, Matthew C.

1991-01-01

On 18 September 1989 the western part ofHurricane Hugo crossed eastern Puerto Rico and the Luquillo Experimental Forest (LEF). Storm-facing slopes on the northeastern part of the island that were within 15 km of the eye and received greater than 200 mm of rain were most affected by the storm. In the LEF and nearby area, recurrence intervals associated with Hurricane Hugo were 50 yr for wind velocity, 10 to 31 yr for stream discharge, and 5 yr for rainfall intensity. To compare the magnitudes of the six hurricanes to pass over PuertoRico since 1899, 3 indices were developed using the standardized values of the product of: the maximum sustained wind speed at San Juan squared and storm duration; the square of the product of the maximum sustained wind velocity at San Juan and the ratio of the distance between the hurricane eye and San Juan to the distance between the eye and percentage of average annual rainfall delivered by the storm. Based on these indices, HurricaneHugo was of moderate intensity. However, because of the path of Hurricane Hugo, only one of these six storms (the 1932 storm) caused more damage to the LEF than Hurricane Hugo. Hurricanes of Hugo's magnitude are estimated to pass over the LEF once every 50-60 yr, on average. 

Water resources planning for rivers draining into mobile bay

NASA Technical Reports Server (NTRS)

Ng, S.; April, G. C.

1976-01-01

A hydrodynamic model describing water movement and tidal elevation is formulated, computed, and used to provide basic data about water quality in natural systems. The hydrodynamic model is based on two-dimensional, unsteady flow equations. The water mass is considered to be reasonably mixed such that integration (averaging) in the depth direction is a valid restriction. Convective acceleration, the Coriolis force, wind and bottom interactions are included as contributing terms in the momentum equations. The solution of the equations is applied to Mobile Bay, and used to investigate the influence that river discharge rate, wind direction and speed, and tidal condition have on water circulation and holdup within the bay. Storm surge conditions, oil spill transport, artificial island construction, dredging, and areas subject to flooding are other topics which could be investigated using the mathematical modeling approach.

Impact of Superstorm Sandy on Medicare Patients' Utilization of Hospitals and Emergency Departments.

PubMed

Stryckman, Benoit; Walsh, Lauren; Carr, Brendan G; Hupert, Nathaniel; Lurie, Nicole

2017-10-01

National health security requires that healthcare facilities be prepared to provide rapid, effective emergency and trauma care to all patients affected by a catastrophic event. We sought to quantify changes in healthcare utilization patterns for an at-risk Medicare population before, during, and after Superstorm Sandy's 2012 landfall in New Jersey (NJ). This study is a retrospective cohort study of Medicare beneficiaries impacted by Superstorm Sandy. We compared hospital emergency department (ED) and healthcare facility inpatient utilization in the weeks before and after Superstorm Sandy landfall using a 20% random sample of Medicare fee-for-service beneficiaries continuously enrolled in 2011 and 2012 (N=224,116). Outcome measures were pre-storm discharges (or transfers), average length of stay, service intensity weight, and post-storm ED visits resulting in either discharge or hospital admission. In the pre-storm week, hospital transfers from skilled nursing facilities (SNF) increased by 39% and inpatient discharges had a 0.3 day decreased mean length of stay compared to the prior year. In the post-storm week, ED visits increased by 14% statewide; of these additional "surge" patients, 20% were admitted to the hospital. The increase in ED demand was more than double the statewide average in the most highly impacted coastal regions (35% versus 14%). Superstorm Sandy impacted both pre- and post-storm patient movement in New Jersey; post-landfall ED surge was associated with overall storm impact, which was greatest in coastal counties. A significant increase in the number and severity of pre-storm transfer patients, in particular from SNF, as well as in post-storm ED visits and inpatient admissions, draws attention to the importance of collaborative regional approaches to healthcare in large-scale events.

Impact of the winter 2013-2014 series of severe Western Europe storms on a double-barred sandy coast: Beach and dune erosion and megacusp embayments

NASA Astrophysics Data System (ADS)

Castelle, Bruno; Marieu, Vincent; Bujan, Stéphane; Splinter, Kristen D.; Robinet, Arhur; Sénéchal, Nadia; Ferreira, Sophie

2015-06-01

The winter of 2013/2014 was characterized by a striking pattern of temporal and spatial extreme storm wave clustering in Western Europe. The 110-km long Gironde coast, SW France, was exposed to the most energetic wave conditions over the last 18 years. The period was outstanding in terms of the available energy to move sediment and cause large-scale erosion with the 2-month average significant wave height (Hs) exceeding 3.6 m, just below the 0.95 quantile, and 4 distinct 10-year return period storms with Hs > 9 m. These storm waves caused unprecedented beach and dune erosion along the Gironde coast, including severely damaged sea defences at the coastal towns. At the end of the winter, dune erosion scarp height was highly variable alongshore and often exceeded 10 m. Megacusp embayments were observed along the Gironde coast with an average alongshore spacing of 1000 m in the south progressively decreasing to 500 m in the north, with an average cross-shore amplitude of 20 m. While beach megacusps were previously observed to systematically couple to the inner bar along the Gironde coast during low- to moderate-energy wave conditions, severe storm-driven megacusp embayments cutting the dune were found to be enforced and coupled to the outer crescentic bar. A detailed inspection of the 1500 m-long bimonthly topographic surveys of Truc Vert beach shows that in early January 2014 the outstanding shore-normal incident storm swell 'Hercules', with Hs and peak wave period Tp peaking at 9.6 m and 22 s, respectively, triggered the formation of a localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m. The subsequent storms progressively smoothed the megacusp by the end of the winter, mostly through severe erosion of the megacusp horns. Because of the very long period (16 s < Tp < 23 s) storm waves with persistent shore-normal incidence, the well-developed outer crescentic bar observed prior to the winter did not straighten. Instead, the outer-bar three-dimensionality developed further, particularly during 'Hercules'. Our observations indicate that both the antecedent outer sandbar morphology and storm wave characteristics, including period and angle of incidence, govern patterns of beach and dune erosion along open multiple-barred sandy coasts during severe storms.

Global Summary MGS TES Data and Mars-Gram Validation

NASA Technical Reports Server (NTRS)

Justus, C.; Johnson, D.; Parker, Nelson C. (Technical Monitor)

2002-01-01

Mars Global Reference Atmospheric Model (Mars-GRAM 2001) is an engineering-level Mars atmosphere model widely used for many Mars mission applications. From 0-80 km, it is based on NASA Ames Mars General Circulation Model (MGCM), while above 80 km it is based on University of Arizona Mars Thermospheric General Circulation Model. Mars-GRAM 2001 and MGCM use surface topograph$ from Mars Global Surveyor Mars Orbiting Laser Altimeter (MOLA). Validation studies are described comparing Mars-GRAM with a global summary data set of Mars Global Surveyor Thermal Emission Spectrometer (TES) data. TES averages and standard deviations were assembled from binned TES data which covered surface to approx. 40 km, over more than a full Mars year (February, 1999 - June, 2001, just before start of a Mars global dust storm). TES data were binned in 10-by-10 degree latitude-longitude bins (i.e. 36 longitude bins by 19 latitude bins), 12 seasonal bins (based on 30 degree increments of Ls angle). Bin averages and standard deviations were assembled at 23 data levels (temperature at 21 pressure levels, plus surface temperature and surface pressure). Two time-of day bins were used: local time near 2 or 14 hours local time). Two dust optical depth bins wereused: infrared optical depth either less than or greater than 0.25 (which corresponds to visible optical depth either less than or greater than about 0.5). For interests in aerocapture and precision entry and landing, comparisons focused on atmospheric density. TES densities versus height were computed from TES temperature versus pressure, using assumptions of perfect gas law and hydrostatics. Mars-GRAM validation studies used density ratio (TES/Mars-GRAM) evaluated at data bin center points in space and time. Observed average TES/Mars-GRAM density ratios were generally 1+/-0.05, except at high altitudes (15-30 km, depending on season) and high latitudes (> 45 deg N), or at most altitudes in the southern hemisphere at Ls approx. 90 and 180deg). Compared to TES averages for a given latitude and season, TES data had average density standard deviation about the mean of approx. 65-10.5% (varying with height) for all data, or approx. 5-12%, depending on time of day and dust optical depth. Average standard deviation of TES/Mars-GRAM density ratio was 8.9% for local time 2 hours and 7.1% for local time 14 hours. Thus standard deviation of observed TES/Mars-GRAM density ratio, evaluated at matching positions and times, is about the same as the standard deviation of TES data about the TES mean value at a given position and season.

Variation of curve number with storm depth

NASA Astrophysics Data System (ADS)

Banasik, K.; Hejduk, L.

2012-04-01

The NRCS Curve Number (known also as SCS-CN) method is well known as a tool in predicting flood runoff depth from small ungauged catchment. The traditional way of determination the CNs, based on soil characteristics, land use and hydrological conditions, seemed to have tendency to overpredict the floods in some cases. Over 30 year rainfall-runoff data, collected in two small (A=23.4 & 82.4 km2), lowland, agricultural catchments in Center of Poland (Banasik & Woodward 2010), were used to determine runoff Curve Number and to check a tendency of changing. The observed CN declines with increasing storm size, which according recent views of Hawkins (1993) could be classified as a standard response of watershed. The analysis concluded, that using CN value according to the procedure described in USDA-SCS Handbook one receives representative value for estimating storm runoff from high rainfall depths in the analyzes catchments. This has been confirmed by applying "asymptotic approach" for estimating the watershed curve number from the rainfall-runoff data. Furthermore, the analysis indicated that CN, estimated from mean retention parameter S of recorded events with rainfall depth higher than initial abstraction, is also approaching the theoretical CN. The observed CN, ranging from 59.8 to 97.1 and from 52.3 to 95.5, in the smaller and the larger catchment respectively, declines with increasing storm size, which has been classified as a standard response of watershed. The investigation demonstrated also changeability of the CN during a year, with much lower values during the vegetation season. Banasik K. & D.E. Woodward (2010). "Empirical determination of curve number for a small agricultural watrshed in Poland". 2nd Joint Federal Interagency Conference, Las Vegas, NV, June 27 - July 1, 2010 (http://acwi.gov/sos/pubs/2ndJFIC/Contents/10E_Banasik_ 28_02_10. pdf). Hawkins R. H. (1993). "Asymptotic determination of curve numbers from data". Journal of Irrigation and Drainage Division. American Society of Civil Engineers, 119(2). pp. 334-345. ACKNOWLEDGMENTS The investigation described in the paper is part of the research project no. N N305 396238 founded by PL-Ministry of Science and Higher Education. The support provided by this organization is gratefully acknowledged.

Alongshore Variation in the Depth of Activation: Implications of Oil Residence Time

NASA Astrophysics Data System (ADS)

Flores, P.; Houser, C.

2016-12-01

In 2010 the Deepwater Horizon Oil Spill released approximately 5 million barrels of oil into the Gulf of Mexico just as the nearshore and beach profile were recovering from winter storms. As a consequence, oil mats and tar balls were trapped at depth within the beach and nearshore profile. Excavation of this buried oil during subsequent storms creates the potential for the contamination of adjacent beaches and the degradation of marine ecosystems, which can in turn negatively impact local economies that depend on fisheries and tourism. The potential for oil burial and persistence is dependent on four things: the physio-chemical nature of the oil as it reaches the nearshore environment, the pre-existing morphology of the beach and nearshore, and the evolution of that morphology after the oil is deposited. The depth at which the oil is buried is also dependent on the beach profile during the time of the spill. The purpose of this study is to characterize the alongshore variation in depth of activation on a Deepwater Horizon impacted section of Pensacola Beach, Florida with regards to the implications of oil residence time. Ground- Penetrating Radar (GPR) surveys were conducted along two parallel 1-km transects adjacent to the swash zone and the dune. Additional cross- shore transects were completed every 150 m from the base of the dune to the top of the swash zone. Sediments cores were taken at the crossing points of the alongshore and cross-shore transects, to calibrate the GPR surveys and complete an elemental analysis for the identification of storm layers. The cores were also analyzed for the presence of buried oil.

Large-scale environmental influences on the benthic macroinfauna of the southern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Hernández-Arana, Hector A.; Rowden, Ashley A.; Attrill, Martin J.; Warwick, Richard M.; Gold-Bouchot, Gerardo

2003-12-01

The influence of large-scale natural disturbance from winter storms ('northers') and river runoff on the macrobenthic community structure of the southern Gulf of Mexico was investigated in both carbonate and transitional carbonate-terrigenous sedimentary environments. Samples of the infauna were obtained in three seasons from 13 stations from two 250 km transects along 80-170 and 20-50 m water depth. Samples after the northers season had the lowest total number of families and individuals, 114 and 2940, respectively, compared to the dry and rainy seasons with 129 and 132 families and 11580 and 15266 individuals, respectively. Spatial patterns of macroinfauna composition varied across and along the shelf as a response to sedimentary environments and depth. Coarser sediments from the carbonate area harboured the highest mean densities per station with 500-24,000 individuals m -2 and 108-122 families in total, compared to the transitional sediment with 500-8200 individuals m -2 and 56-74 families across the three seasons. Univariate and multivariate statistical techniques demonstrated that low densities and number of taxa were associated with winter storms, but storm influence was dependent on depth and sediment type. Multiple linear regression analysis and BIOENV analysis indicated that sediment mean grain size, percentage of clay and organic matter best explained the macroinfauna spatial patterns, although BIOENV indicated that depth has an overriding role. An increase in densities of opportunistic taxa (numerous polychaetes of small sizes) was observed four months after the 'northers' and this was more evident in the area of carbonate sediment. Additionally a combined disturbance from northers and river runoff is suspected to be responsible for a naturally impoverished macroinfauna community in the transitional sedimentary environment.

Field application of farmstead runoff to vegetated filter strips: surface and subsurface water quality assessment.

PubMed

Larson, Rebecca A; Safferman, Steven I

2012-01-01

Farmstead runoff poses significant environmental impacts to ground and surface waters. Three vegetated filter strips were assessed for the treatment of dairy farmstead runoff at the soil surface and subsurface at 0.3- or 0. 46-m and 0. 76-m depths for numerous storm events. A medium-sized Michigan dairy was retrofitted with two filter strips on sandy loam soil and a third filter strip was implemented on a small Michigan dairy with sandy soil to collect and treat runoff from feed storage, manure storage, and other impervious farmstead areas. All filter strips were able to eliminate surface runoff via infiltration for all storm events over the duration of the study, eliminating pollutant contributions to surface water. Subsurface effluent was monitored to determine the contributing groundwater concentrations of numerous pollutants including chemical oxygen demand (COD), metals, and nitrates. Subsurface samples have an average reduction of COD concentrations of 20, 11, and 85% for the medium dairy Filter Strip 1 (FS1), medium dairy Filter Strip 2 (FS2), and the small Michigan dairy respectively, resulting in average subsurface concentrations of 355, 3960, and 718 mg L COD. Similar reductions were noted for ammonia and total Kjeldahl nitrogen (TKN) in the subsurface effluent. The small Michigan dairy was able to reduce the pollutant leachate concentrations of COD, TKN, and ammonia over a range of influent concentrations. Increased influent concentrations in the medium Michigan dairy filter strips resulted in an increase in COD, TKN, and ammonia concentrations in the leachate. Manganese was leached from the native soils at all filter strips as evidenced by the increase in manganese concentrations in the leachate. Nitrate concentrations were above standard drinking water limits (10 mg L), averaging subsurface concentrations of 11, 45, and 25 mg L NO-N for FS1, FS2, and the small Michigan dairy, respectively. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Hurricanes 2004: An overview of their characteristics and coastal change

USGS Publications Warehouse

Sallenger, Asbury H.; Stockdon, Hilary; Fauver, Laura A.; Hansen, Mark; Thompson, David; Wright, C. Wayne; Lillycrop, Jeff

2006-01-01

Four hurricanes battered the state of Florida during 2004, the most affecting any state since Texas endured four in 1884. Each of the storms changed the coast differently. Average shoreline change within the right front quadrant of hurricane force winds varied from 1 m of shoreline advance to 20 m of retreat, whereas average sand volume change varied from 11 to 66 m3 m−1 of net loss (erosion). These changes did not scale simply with hurricane intensity as described by the Saffir-Simpson Hurricane Scale. The strongest storm of the season, category 4 Hurricane Charley, had the least shoreline retreat. This was likely because of other factors like the storm's rapid forward speed and small size that generated a lower storm surge than expected. Two of the storms, Hurricanes Frances and Jeanne, affected nearly the same area on the Florida east coast just 3 wk apart. The first storm, Frances, although weaker than the second, caused greater shoreline retreat and sand volume erosion. As a consequence, Hurricane Frances may have stripped away protective beach and exposed dunes to direct wave attack during Jeanne, although there was significant dune erosion during both storms. The maximum shoreline change for all four hurricanes occurred during Ivan on the coasts of eastern Alabama and the Florida Panhandle. The net volume change across a barrier island within the Ivan impact zone approached zero because of massive overwash that approximately balanced erosion of the beach. These data from the 2004 hurricane season will prove useful in developing new ways to scale and predict coastal-change effects during hurricanes.

Changes in thunderstorm characteristics due to feeder cloud merging

NASA Astrophysics Data System (ADS)

Sinkevich, Andrei A.; Krauss, Terrence W.

2014-06-01

Cumulus cloud merging is a complex dynamical and microphysical process in which two convective cells merge into a single cell. Previous radar observations and numerical simulations have shown a substantial increase in the maximum area, maximum echo top and maximum reflectivity as a result of the merging process. Although the qualitative aspects of merging have been well documented, the quantitative effects on storm properties remain less defined. Therefore, a statistical assessment of changes in storm characteristics due to merging is of importance. Further investigation into the effects of cloud merging on precipitation flux (Pflux) in a statistical manner provided the motivation for this study in the Asir region of Saudi Arabia. It was confirmed that merging has a strong effect on storm development in this region. The data analysis shows that an increase in the median of the distribution of maximum reflectivity was observed just after merging and was equal to 3.9 dBZ. A detailed analysis of the individual merge cases compared the merged storm Pflux and mass to the sum of the individual Feeder and Storm portions just before merging for each case. The merged storm Pflux increased an average of 106% over the 20-min period after merging, and the mass increased on average 143%. The merged storm clearly became larger and more severe than the sum of the two parts prior to merging. One consequence of this study is that any attempts to evaluate the precipitation enhancement effects of cloud seeding must also include the issue of cloud mergers because merging can have a significant effect on the results.

An Investigation of Dust Storms Observed with the Mars Color Imager

NASA Technical Reports Server (NTRS)

Guzewich, Scott D.; Toigo, Anthony D.; Wang, Huiqun

2017-01-01

Daily global imaging by the Mars Color Imager (MARCI) continues the record of the Mars Orbiter Camera (MOC) and has allowed creation of a long-duration record of Martian dust storms. We observe dust storms over the first two Mars years of the MARCI record, including tracking individual storms over multiple sols, as well as tracking the growth and recession of the seasonal polar caps. Using the combined 6 Mars year record of textured dust storms (storms with visible textures on the observed dust cloud tops), we study the relationship between textured dust storm activity and meteorology (as simulated by the MarsWRF general circulation model) and surface properties. We find that textured dust storms preferentially occur in places and seasons with above average surface wind stress. Textured dust storm occurrence also has a modest linear anti-correlation with surface albedo (0.43) and topography (0.40). Lastly, we perform an empirical orthogonal function (EOF) analysis on the distribution of occurrence of textured dust storms and find that over 50 of the variance in textured dust storm activity can be explained by two EOF modes. We associate the first EOF mode with cap-edge storms just before Ls = 180deg and the second EOF mode with flushing dust storms that occur from Ls = 180-210deg and again near Ls = 320deg.

Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India)

NASA Astrophysics Data System (ADS)

Reuter, M.; Piller, W. E.; Harzhauser, M.; Kroh, A.

2013-09-01

Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27-24 Ma). Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system at the Oligocene-Miocene boundary. The vast shell concentrations are comprised of a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deeper to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished, each recording a relative storm wave base. (1) A shallow storm wave base is shown by nearshore molluscs, reef corals and Clypeaster echinoids; (2) an intermediate storm wave base depth is indicated by lepidocyclinid foraminifers, Eupatagus echinoids and corallinacean algae; and (3) a deep storm wave base is represented by an Amussiopecten bivalve-Schizaster echinoid assemblage. These wave base depth estimates were used for the reconstruction of long-term tropical storm intensity during the late Oligocene. The development and intensification of cyclones over the recent Arabian Sea is primarily limited by the atmospheric monsoon circulation and strength of the associated vertical wind shear. Therefore, since the topographic boundary conditions for the Indian monsoon already existed in the late Oligocene, the reconstructed long-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~ 26 Ma followed by a period of monsoon weakening during the peak of the late Oligocene global warming (~ 24 Ma).

Hurricane Harvey Rainfall, Did It Exceed PMP and What are the Implications?

NASA Astrophysics Data System (ADS)

Kappel, B.; Hultstrand, D.; Muhlestein, G.

2017-12-01

Rainfall resulting from Hurricane Harvey reached historic levels over the coastal regions of Texas and Louisiana during the last week of August 2017. Although extreme rainfall from this landfalling tropical system is not uncommon in the region, Harvey was unique in that it persisted over the same general location for several days, producing volumes of rainfall not previously observed in the United States. Devastating flooding and severe stress to infrastructure in the region was the result. Coincidentally, Applied Weather Associates had recently completed an updated statewide Probable Maximum Precipitation (PMP) study for Texas. This storm proved to be a real-time test of the adequacy of those values. AWA calculates PMP following a storm-based approach. This same approach was use in the HMRs. Therefore inclusion of all PMP-type storms is critically important to ensuring that appropriate PMP values are produced. This presentation will discuss the analysis of the Harvey rainfall using the Storm Precipitation Analysis System (SPAS) program used to analyze all storms used in PMP development, compare the results of the Harvey rainfall analysis against previous similar storms, and provide comparisons of the Harvey rainfall against previous and current PMP depths. Discussion will be included regarding the implications of the storm on previous and future PMP estimates, dam safety design, and infrastructure vulnerable to extreme flooding.

Total Lightning and Radar Storm Characteristics Associated with Severe Storms in Central Florida

NASA Technical Reports Server (NTRS)

Goodman, Steven J.; Raghavan, Ravi; Ramachandran, Rahul; Buechler, Dennis; Hodanish, Stephen; Sharp, David; Williams, Earle; Boldi, Bob; Matlin, Anne; Weber, Mark

1998-01-01

A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms (Taylor, 1973; Johnson, 1980; Goodman and Knupp, 1993) but not always. Taylor found that 23% of nontornadic storms and 1% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (IC) lightning than cloud-to-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tomadic storms will be dominated by intracloud lightning-with an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et al. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, F5) tornado formation. Studies of non-tomadic storms have also shown that total lightning flash rates track the updraft, with rates increasing as the updraft intensities and decreasing rapidly with cessation of vertical growth or downburst onset (Goodman et al., 1988; Williams et al., 1989). Such relationships result from the development of mixed phase precipitation and increased hydrometer collisions that lead to the efficient separation of charge. Correlations between updraft strength and other variables such as cloud-top height, cloud water mass, and hail size have also been observed.

Models of bright storm clouds and related dark ovals in Saturn's Storm Alley as constrained by 2008 Cassini/VIMS spectra

NASA Astrophysics Data System (ADS)

Sromovsky, L. A.; Baines, K. H.; Fry, P. M.

2018-03-01

A 5° latitude band on Saturn centered near planetocentric latitude 36°S is known as "Storm Alley" because it has been for several extended periods a site of frequent lightning activity and associated thunderstorms, first identified by Porco et al. (2005). The thunderstorms appeared as bright clouds at short and long continuum wavelengths, and over a period of a week or so transformed into dark ovals (Dyudina et al., 2007). The ovals were found to be dark over a wide spectral range, which led Baines et al. (2009) to suggest the possibility that a broadband absorber such as soot produced by lightning could play a significant role in darkening the clouds relative to their surroundings. Here we show that an alternative explanation, which is that the clouds are less reflective because of reduced optical depth, provides an excellent fit to near infrared spectra of similar features obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) in 2008, and leads to a plausible scenario for cloud evolution. We find that the background clouds and the oval clouds are both dominated by the optical properties of a ubiquitous upper cloud layer, which has the same particle size in both regions, but about half the optical depth and physical thickness in the dark oval regions. The dark oval regions are also marked by enhanced emissions in the 5-μm window region, a result of lower optical depth of the deep cloud layer near 3.1-3.8 bar, presumably composed of ammonium hydrosulfide (NH4SH). The bright storm clouds completely block this deep thermal emission with a thick layer of ammonia (NH3) clouds extending from the middle of the main visible cloud layer probably as deep as the 1.7-bar NH3 condensation level. Other condensates might also be present at higher pressures, but are obscured by the NH3 cloud. The strong 3-μm spectral absorption that was displayed by Saturn's Great Storm of 2010-2011 (Sromovsky et al., 2013) is weaker in these storms because the contrast is muted by the overlying cloud deck that these less intense storms do not fully penetrate. Our speculated evolutionary scenario that seems consistent with these results is that deep convection produces lightning and bright clouds of large ammonia particles that rise up into the mid level of the overlying visible deck, pushing out the particles in that layer with the outflow at the top of the convective towers. When the convective pulse subsides, these large particles fall out of the column within a week or so, leaving behind less optical depth than background clouds, making them appear darker because they are less reflective. However, this simple picture does not explain all details of the phenomenon, e.g. the irregular morphology of the bright convective regions and the stable regular shapes of the dark ovals that are formed in their wake.

Time delay between the SYMH and the solar wind energy input during intense storms determined by response function analysis

NASA Astrophysics Data System (ADS)

Cao, X.; Du, A.

2014-12-01

We statistically studied the response time of the SYMH to the solar wind energy input ɛ by using the RFA approach. The average response time was 64 minutes. There was no clear trend among these events concerning to the minimum SYMH and storm type. It seems that the response time of magnetosphere to the solar wind energy input is independent on the storm intensity and the solar wind condition. The response function shows one peak even when the solar wind energy input and the SYMH have multi-peak. The response time exhibits as the intrinsic property of the magnetosphere that stands for the typical formation time of the ring current. This may be controlled by magnetospheric temperature, average number density, the oxygen abundance et al.

Characteristics of the most intense lightning storm ever recorded at the CN Tower

NASA Astrophysics Data System (ADS)

Hussein, A. M.; Kazazi, S.; Anwar, M.; Yusouf, M.; Liatos, P.

2017-02-01

Lightning strikes to the CN Tower have been optically observed since 1978. In 1990, five independent systems started to operate to simultaneously record parameters of lightning strikes to the tower, including the time derivative of the current, the associated electric and magnetic fields, and the channel optical characteristics. On August 24, 2011, during an unusually severe lightning storm, video records showed that the CN Tower was struck with 52 lightning flashes within 84 min and 6.9 s. Thus, this storm produced, on average, a flash to the tower every 99 s. However, the CN Tower lightning current derivative measurement system only recorded 32 flashes, which were perfectly time-matched with 32 of the 52 video-recorded flashes. It is found that the current derivative measurement system recorded every video-recorded flash that contained at least one return stroke. Based on the analysis of video records, it is noted that each of the storm's 52 flashes contains an initial-stage current, proving that all flashes were upward initiated. This unique CN Tower storm - the most intense ever recorded at the tower - is here thoroughly analyzed, based on video and current records. The inter-flash time within the storm is found to vary between 10.6 s and 274 s, with an overall average of 98 s. It is also found that the inter-flash time between successive non-return-stroke flashes is on average 64% longer than that for successive flashes containing return strokes. Statistical analysis of video and current data clearly reveals that the time duration of flashes containing initial-stage currents and return strokes is on average 27% longer than that of flashes that only have initial-stage currents. Furthermore, it is important to note that the time duration of the initial-stage current in flashes containing no return strokes is on average 76% longer than that in flashes containing return strokes. Therefore, it is possible to conclude that if the time duration of the initial-stage current in a flash is long enough, resulting in large charge transfer, then there is less probability of having return strokes following it. The 32 current-recorded flashes contain a total of 156 return strokes, with an average multiplicity of 4.875. It is worth mentioning that during one decade, 1992-2001, the CN Tower current derivative measurement system only recorded 478 return strokes, demonstrating that the number of return strokes recorded at the tower within about 84 min is close to one third of those recorded at the tower during one decade. This finding clearly shows the great value and rarity of the presented extensive lightning current derivative data. Only one of the 32 current-recorded flashes is proved to be positive with a single return stroke. Based on current records, out of a total of 124 inter-stroke time intervals, 94% are found to be within 200 ms, with an overall inter-stroke time average of 68.1 ms. The maximum inter-stroke time recorded during this storm is 726.3 ms, the longest ever recorded at the CN Tower.

Multidecadal Scale Detection Time for Potentially Increasing Atlantic Storm Surges in a Warming Climate

NASA Astrophysics Data System (ADS)

Lee, Benjamin Seiyon; Haran, Murali; Keller, Klaus

2017-10-01

Storm surges are key drivers of coastal flooding, which generate considerable risks. Strategies to manage these risks can hinge on the ability to (i) project the return periods of extreme storm surges and (ii) detect potential changes in their statistical properties. There are several lines of evidence linking rising global average temperatures and increasingly frequent extreme storm surges. This conclusion is, however, subject to considerable structural uncertainty. This leads to two main questions: What are projections under various plausible statistical models? How long would it take to distinguish among these plausible statistical models? We address these questions by analyzing observed and simulated storm surge data. We find that (1) there is a positive correlation between global mean temperature rise and increasing frequencies of extreme storm surges; (2) there is considerable uncertainty underlying the strength of this relationship; and (3) if the frequency of storm surges is increasing, this increase can be detected within a multidecadal timescale (≈20 years from now).

GPU-Meta-Storms: computing the structure similarities among massive amount of microbial community samples using GPU.

PubMed

Su, Xiaoquan; Wang, Xuetao; Jing, Gongchao; Ning, Kang

2014-04-01

The number of microbial community samples is increasing with exponential speed. Data-mining among microbial community samples could facilitate the discovery of valuable biological information that is still hidden in the massive data. However, current methods for the comparison among microbial communities are limited by their ability to process large amount of samples each with complex community structure. We have developed an optimized GPU-based software, GPU-Meta-Storms, to efficiently measure the quantitative phylogenetic similarity among massive amount of microbial community samples. Our results have shown that GPU-Meta-Storms would be able to compute the pair-wise similarity scores for 10 240 samples within 20 min, which gained a speed-up of >17 000 times compared with single-core CPU, and >2600 times compared with 16-core CPU. Therefore, the high-performance of GPU-Meta-Storms could facilitate in-depth data mining among massive microbial community samples, and make the real-time analysis and monitoring of temporal or conditional changes for microbial communities possible. GPU-Meta-Storms is implemented by CUDA (Compute Unified Device Architecture) and C++. Source code is available at http://www.computationalbioenergy.org/meta-storms.html.

Comparison between Measured and Calculated Sediment Transport Rates in North Fork Caspar Creek, California

NASA Astrophysics Data System (ADS)

Kim, T. W.; Yarnell, S. M.; Yager, E.; Leidman, S. Z.

2015-12-01

Caspar Creek is a gravel-bedded stream located in the Jackson Demonstration State Forest in the coast range of California. The Caspar Creek Experimental Watershed has been actively monitored and studied by the Pacific Southwest Research Station and California Department of Forestry and Fire Protection for over five decades. Although total annual sediment yield has been monitored through time, sediment transport during individual storm events is less certain. At a study site on North Fork Caspar Creek, cross-section averaged sediment flux was collected throughout two storm events in December 2014 and February 2015 to determine if two commonly used sediment transport equations—Meyer-Peter-Müller and Wilcock—approximated observed bedload transport. Cross-section averaged bedload samples were collected approximately every hour during each storm event using a Helley-Smith bedload sampler. Five-minute composite samples were collected at five equally spaced locations along a cross-section and then sieved to half-phi sizes to determine the grain size distribution. The measured sediment flux values varied widely throughout the storm hydrographs and were consistently less than two orders of magnitude in value in comparison to the calculated values. Armored bed conditions, changing hydraulic conditions during each storm and variable sediment supply may have contributed to the observed differences.

Effect of storms on Barrier Island dynamics, Core Banks, Cape Lookout National Seashore, North Carolina, 1960-2001

USGS Publications Warehouse

Riggs, Stanley R.; Ames, Dorothea V.

2007-01-01

The effect of storms on long-term dynamics of barrier islands was evaluated on Core Banks, a series of barrier islands that extend from Cape Lookout to Okracoke Inlet in the Cape Lookout National Seashore, North Carolina. Shoreline and elevation changes were determined by comparing 77 profiles and associated reference markers established by the U.S. Army Corps of Engineers (USACE) on Core Banks from June 1960 to July 1962 to a follow-up survey by Godfrey and Godfrey (G&G) in 1971 and a survey by the Department of Geology at East Carolina University (ECU) in 2001, in which 57 of the original 77 profiles were located. Evaluation of the baseline data associated with the USACE study supplies an important record of barrier island response to two specific storm events—Hurricane Donna in September 1960 and the Ash Wednesday extra-tropical cyclone in March 1962. The 1962 USACE survey was followed by 9 years characterized by no major storms; this low-energy period was captured by the G&G survey in 1971. The G&G survey was followed by 22 years characterized by occasional small to moderate storms. Starting in 1993, however, and continuing through 1999, the North Carolina coast experienced a major increase in storm activity, with seven major hurricanes impacting Core Banks. Both the USACE 1960–1962 and G&G 1962–1971 surveys produced short-term data sets that reflected very different sets of weather conditions. The ECU 2001 survey data were then compared with the USACE 1960 survey data to develop a long-term (41 years) data set for shoreline erosion on Core Banks. Those resulting long-term data were compared with the long-term (52 years) data sets by the North Carolina Division of Coastal Management (NCDCM) from 1940–1992 and 1946–1998; a strong positive correlation and very similar rates of average annual erosion resulted. However, the ECU and NCDCM long-term data sets did not correlate with either of the USACE and G&G short-term survey data and had very different average annual erosion rates. The average annual long-term rate of shoreline erosion for all of Core Banks and for both the ECU 1960–2001 and the NCDCM 1946–1998 surveys was -5 feet per year (ft/yr). These long-term rates of shoreline recession are in strong contrast with the short-term, storm-dominated rates of shoreline erosion for all of Core Banks developed by the USACE 1960–1961 and USACE 1961–1962 surveys, which have average annual erosion rates of -40 ft/yr and -26 ft/yr, respectively, and range from -226 feet (ft) to +153 ft. The combined short-term, storm-dominated shoreline erosion rate for the USACE surveys (1960–1962) was -36 ft/yr. In contrast, the average annual short-term, non-stormy period G&G 1962–1971 survey demonstrated shoreline accretion for all of Core Banks with an average annual rate of +12 ft/yr. In general, North Core Banks has higher erosion and accretion rates than South Core Banks. In the 1961 survey, the USACE installed 231 reference markers (RM-0 is closest to the ocean and RM-2 is farthest from the ocean) along the 77 profiles, as well as 33 reference markers labeled RM-4, RM-6, and RM-8 in the wider portions of the islands. The G&G survey recovered a total of 141 reference markers (61 percent), and the ECU survey recovered a total of 83 reference markers (36 percent) of the RM-0, RM-1, and RM-2 markers. The average ground elevation measured by the USACE in 1961 was RM-0 = +5.8 ft, RM-1 = +5.2 ft, and RM-2 = +4.8 ft. The G&G 1970 survey measured average ground elevations of RM-0 = +6.7 ft, RM-1 = +6.4 ft, and RM-2 = +6.1 ft, and the average ground elevation measured by ECU in 2001 was RM-0 = +10.1 ft, RM-1 = +9.1 ft, and RM-2 = +8.5 ft. The latter numbers represent approximately an overall 72-percent increase in island elevation from 1961 to 2001. Based on aerial photographic time-slice analyses, it is hypothesized that this increase in island elevation occurred during the post-1962 period with storm overwash systematically raising the island elevation through time, which in turn led to decreased numbers of overwash events. The latter processes and responses in turn led to a substantial increase in vegetative growth on the barrier island, as well as submerged aquatic vegetation on the back-barrier sand shoals. Integration of the USACE, G&G, ECU, and NCDCM shoreline erosion data for Core Banks shows several important points about shoreline recession. (1) The ECU and NCDCM data sets demonstrate that there is an ongoing net, long-term, but small-scale shoreline recession associated with Core Banks; (2) the USACE short-term data sets demonstrate that processes associated with individual storm events or sets of events produce extremely large-scale changes that include both erosion and accretion; (3) the short-term, non-stormy period data set of G&G demonstrates that if given enough time between storm events, barriers can rebuild to their pre-storm period conditions; and (4) the post-storm response generally tends to approach the pre-storm location, but rarely reaches it before the next storm or stormy period sets in. The result is the net long-term change documented by both the ECU 1960–2001 and NCDCM 1946–1998 Core Banks data sets that resulted in erosion rates ranging from 0 to -30 ft/yr with net annual average recession rates of -5 ft/yr. Analysis and comparison of these data sets supply important information for understanding the dynamics and responses of barrier island systems through time. In addition, the results of the present study on Core Banks supply essential process-response information that can be used to design and implement management plans for the Cape Lookout and Cape Hatteras National Seashores and for other seashores in the U.S. National Park Service system.

Multilinear approach to the precipitation-lightning relationship: a case study of summer local electrical storms in the northern part of Spain during 2002-2009 period

NASA Astrophysics Data System (ADS)

Herrero, I.; Ezcurra, A.; Areitio, J.; Diaz-Argandoña, J.; Ibarra-Berastegi, G.; Saenz, J.

2013-11-01

Storms developed under local instability conditions are studied in the Spanish Basque region with the aim of establishing precipitation-lightning relationships. Those situations may produce, in some cases, flash flood. Data used correspond to daily rain depth (mm) and the number of CG flashes in the area. Rain and lightning are found to be weakly correlated on a daily basis, a fact that seems related to the existence of opposite gradients in their geographical distribution. Rain anomalies, defined as the difference between observed and estimated rain depth based on CG flashes, are analysed by PCA method. Results show a first EOF explaining 50% of the variability that linearly relates the rain anomalies observed each day and that confirms their spatial structure. Based on those results, a multilinear expression has been developed to estimate the rain accumulated daily in the network based on the CG flashes registered in the area. Moreover, accumulates and maximum values of rain are found to be strongly correlated, therefore making the multilinear expression a useful tool to estimate maximum precipitation during those kind of storms.

Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

USGS Publications Warehouse

McMullen, Katherine Y.; Poppe, Lawrence J.; Parker, Castle E.

2015-01-01

Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

Framework for event-based semidistributed modeling that unifies the SCS-CN method, VIC, PDM, and TOPMODEL

NASA Astrophysics Data System (ADS)

Bartlett, M. S.; Parolari, A. J.; McDonnell, J. J.; Porporato, A.

2016-09-01

Hydrologists and engineers may choose from a range of semidistributed rainfall-runoff models such as VIC, PDM, and TOPMODEL, all of which predict runoff from a distribution of watershed properties. However, these models are not easily compared to event-based data and are missing ready-to-use analytical expressions that are analogous to the SCS-CN method. The SCS-CN method is an event-based model that describes the runoff response with a rainfall-runoff curve that is a function of the cumulative storm rainfall and antecedent wetness condition. Here we develop an event-based probabilistic storage framework and distill semidistributed models into analytical, event-based expressions for describing the rainfall-runoff response. The event-based versions called VICx, PDMx, and TOPMODELx also are extended with a spatial description of the runoff concept of "prethreshold" and "threshold-excess" runoff, which occur, respectively, before and after infiltration exceeds a storage capacity threshold. For total storm rainfall and antecedent wetness conditions, the resulting ready-to-use analytical expressions define the source areas (fraction of the watershed) that produce runoff by each mechanism. They also define the probability density function (PDF) representing the spatial variability of runoff depths that are cumulative values for the storm duration, and the average unit area runoff, which describes the so-called runoff curve. These new event-based semidistributed models and the traditional SCS-CN method are unified by the same general expression for the runoff curve. Since the general runoff curve may incorporate different model distributions, it may ease the way for relating such distributions to land use, climate, topography, ecology, geology, and other characteristics.

Characterization and radiative impact of dust aerosols over northwestern part of India: a case study during a severe dust storm

NASA Astrophysics Data System (ADS)

Singh, Atinderpal; Tiwari, Shani; Sharma, Deepti; Singh, Darshan; Tiwari, Suresh; Srivastava, Atul Kumar; Rastogi, Neeraj; Singh, A. K.

2016-12-01

The present study focused on examining the impact of a severe dust storm (DS) on aerosol properties over Patiala (30.33°N, 76.4°E), a site located in the northwestern part of India during 20th-23rd March, 2012. On 20th March, average PM10 mass concentration increased abruptly from 182 to 817 µg m-3 along with significant increase in the number density of coarser particles (diameter >0.45 µm). During DS, spectral aerosol optical depth (AOD) increases significantly with more increase at longer wavelengths resulting in weak wavelength dependence (AOD at 380 nm increases by 210 % and at 870 nm by 270 % on 20th March). Significant decrease in Ångström exponent (AE; α 380-870) from 0.56 to 0.11 and fine-mode fraction (FMF; PM2.5/PM10) from 0.49 to 0.25 indicates dominance of coarser particles over the station. Net short wave (SW) radiation flux has been decreased by 20 % and single scattering albedo (SSA675) has been increased from 0.86 (19th March) to 0.90 (20th March). This observation is attributed to additional loading of scattering type aerosols on arrival of DS. Wavelength dependence of SSA reverses during DS and it increases with wavelength due to dominance of coarse-mode particles. Atmospheric aerosol radiative forcing (ATM ARF) during DS ranged from +45 to +77 W m-2, consequently heating the lower atmosphere up to 2.2 K day-1. Significant atmospheric heating rate due to severe dust storm may affect the regional atmospheric dynamics and hence the climate system.

Storm surges formation in the White and Barents Seas

NASA Astrophysics Data System (ADS)

Arkhipkin, Victor; Dobrolyubov, Sergey; Korablina, Anastasia; Myslenkov, Stanislav

2016-04-01

Investigation of storm surges in the Arctic seas are of high priority in Russia due to the active development of offshore oil and gas, construction of facilities in the coastal zone, as well as for the safety of navigation. It is important to study the variability of surges, to predict this phenomena and subsequent economic losses, thus including such information into the Russian Arctic Development Program 2020. Surges in the White and Barents Seas are caused mainly by deep cyclones of two types: "diving" from the north (88% of all cyclones) and western. The average height of the storm surges in the White Sea is 0.6-0.9 m. An average duration of storm surges is about 80 hours. Mathematical modeling is used to analyze the characteristics of storm surges formation in the Dvina Bay of the White Sea, and in the Varandey village on the Barents Sea coast. Calculating storm surge heights in the White and Barents seas is performed using the ADCIRC model on an unstructured grid with a step from 20 km in the Barents Sea to 100 m in the White Sea. Unstructured grids allowed keeping small features of the coastline of the White and Barents seas, small islands and shallow banks, and assessing their impact on the development and transformation of wind-generated waves. The ADCIRC model used data of wind field reanalysis CFSv2. The storm surges were simulated for the time period from 1979 to 2010 and included scenarios with / without direct atmospheric pressure forcing, waves and tides. Numerical experiments have revealed distribution of storm surges in channels of the Northern Dvina River delta. The storm surges spreads in the model from the north-north-west of the Dvina Bay. As storm surge moves from the wellhead to the seaside estuary of the Northern Dvina (district Solombala), its height increases from 0.5 to 2 m. We also found a non-linear interaction of the surge and tide during the phase of surge destruction. This phenomenon is the highest in the period of low water, and the smallest in the period full of water. Analysis of storm surges in the Varandey village (the southern part of the Barents Sea) showed that the maximum height of storm surge reached 2.9 m in this region in July, 2010. The work performed was supported by the RSCF (grant № 14-37-00038)

Association of time of occurrence of electrical heart storms with environmental physical activity.

PubMed

Stoupel, Eliiyahu; Kusniec, Jairo; Golovchiner, Gregory; Abramson, Evgeny; Kadmon, Udi; Strasberg, Boris

2014-08-01

Many publications in recent decades have reported a temporal link between medical events and environmental physical activity. The aim of this study was to analyze the time of occurrence of electrical heart storms against levels of cosmological parameters. The sample included 82 patients (71 male) with ischemic cardiomyopathy treated with an implantable cardioverter defibrillator at a tertiary medical center in 1999-2012 (5,114 days). The time of occurrence of all electrical heart storms, defined as three or more events of ventricular tachycardia or ventricular fibrillation daily, was recorded from the defibrillator devices. Findings were analyzed against data on solar, geomagnetic, and cosmic ray (neutron) activity for the same time period obtained from space institutions in the United States and Russia. Electrical storms occurred in all months of the year, with a slight decrease in July, August, and September. Most events took place on days with lower-than-average levels of solar and geomagnetic activity and higher-than-average levels of cosmic ray (neutron) activity. There was a significant difference in mean daily cosmic ray activity between the whole observation period and the days of electrical storm activity (P = 0.0001). These data extend earlier findings on the association of the timing of cardiac events and space weather parameters to the most dangerous form of cardiac arrhythmia-electric storms. Further studies are needed to delineate the pathogenetic mechanism underlying this association. ©2014 Wiley Periodicals, Inc.

Shallow-water seismoacoustic noise generated by tropical storms Ernesto and Florence.

PubMed

Traer, James; Gerstoft, Peter; Bromirski, Peter D; Hodgkiss, William S; Brooks, Laura A

2008-09-01

Land-based seismic observations of double frequency (DF) microseisms generated during tropical storms Ernesto and Florence are dominated by signals in the 0.15-0.5 Hz band. In contrast, data from sea floor hydrophones in shallow water (70 m depth, 130 km off the New Jersey coast) show dominant signals in the ocean gravity-wave frequency band, 0.02-0.18 Hz, and low amplitudes from 0.18 to 0.3 Hz, suggesting significant opposing wave components necessary for DF microseism generation were negligible at the site. Florence produced large waves over deep water while Ernesto only generated waves in coastal regions, yet both storms produced similar spectra. This suggests near-coastal shallow water as the dominant region for observed microseism generation.

L-band microwave remote sensing and land data assimilation improve the representation of pre-storm soil moisture conditions for hydrologic forecasting.

PubMed

Crow, W T; Chen, F; Reichle, R H; Liu, Q

2017-06-16

Recent advances in remote sensing and land data assimilation purport to improve the quality of antecedent soil moisture information available for operational hydrologic forecasting. We objectively validate this claim by calculating the strength of the relationship between storm-scale runoff ratio (i.e., total stream flow divided by total rainfall accumulation in depth units) and pre-storm surface soil moisture estimates from a range of surface soil moisture data products. Results demonstrate that both satellite-based, L-band microwave radiometry and the application of land data assimilation techniques have significantly improved the utility of surface soil moisture data sets for forecasting stream flow response to future rainfall events.

L-band microwave remote sensing and land data assimilation improve the representation of pre-storm soil moisture conditions for hydrologic forecasting

PubMed Central

Crow, W.T.; Chen, F.; Reichle, R.H.; Liu, Q.

2018-01-01

Recent advances in remote sensing and land data assimilation purport to improve the quality of antecedent soil moisture information available for operational hydrologic forecasting. We objectively validate this claim by calculating the strength of the relationship between storm-scale runoff ratio (i.e., total stream flow divided by total rainfall accumulation in depth units) and pre-storm surface soil moisture estimates from a range of surface soil moisture data products. Results demonstrate that both satellite-based, L-band microwave radiometry and the application of land data assimilation techniques have significantly improved the utility of surface soil moisture data sets for forecasting stream flow response to future rainfall events. PMID:29657342

Modeling Earth's Ring Current Using The CIMI Model

NASA Astrophysics Data System (ADS)

Craven, J. D., II; Perez, J. D.; Buzulukova, N.; Fok, M. C. H.

2015-12-01

Earth's ring current is a result of the injection of charged particles trapped in the magnetosphere from solar storms. The enhancement of the ring current particles produces magnetic depressions and disturbances to the Earth's magnetic field known as geomagnetic storms, which have been modeled using the comprehensive inner magnetosphere-ionosphere (CIMI) model. The purpose of this model is to identify and understand the physical processes that control the dynamics of the geomagnetic storms. The basic procedure was to use the CIMI model for the simulation of 15 storms since 2009. Some of the storms were run multiple times, but with varying parameters relating to the dynamics of the Earth's magnetic field, particle fluxes, and boundary conditions of the inner-magnetosphere. Results and images were placed in the TWINS online catalog page for further analysis and discussion. Particular areas of interest were extreme storm events. A majority of storms simulated had average DST values of -100 nT; these extreme storms exceeded DST values of -200 nT. The continued use of the CIMI model will increase knowledge of the interactions and processes of the inner-magnetosphere as well as lead to a better understanding of extreme solar storm events for the future advancement of space weather physics.

Temporal Hyporheic Zone Response to Water Table Fluctuations.

PubMed

Malzone, Jonathan M; Anseeuw, Sierra K; Lowry, Christopher S; Allen-King, Richelle

2016-03-01

Expansion and contraction of the hyporheic zone due to temporal hydrologic changes between stream and riparian aquifer influence the biogeochemical cycling capacity of streams. Theoretical studies have quantified the control of groundwater discharge on the depth of the hyporheic zone; however, observations of temporal groundwater controls are limited. In this study, we develop the concept of groundwater-dominated differential hyporheic zone expansion to explain the temporal control of groundwater discharge on the hyporheic zone in a third-order stream reach flowing through glacially derived terrain typical of the Great Lakes region. We define groundwater-dominated differential expansion of the hyporheic zone as: differing rates and magnitudes of hyporheic zone expansion in response to seasonal vs. storm-related water table fluctuation. Specific conductance and vertical hydraulic gradient measurements were used to map changes in the hyporheic zone during seasonal water table decline and storm events. Planar and riffle beds were monitored in order to distinguish the cause of increasing hyporheic zone depth. Planar bed seasonal expansion of the hyporheic zone was of a greater magnitude and longer in duration (weeks to months) than storm event expansion (hours to days). In contrast, the hyporheic zone beneath the riffle bed exhibited minimal expansion in response to seasonal groundwater decline compared to storm related expansion. Results indicated that fluctuation in the riparian water table controlled seasonal expansion of the hyporheic zone along the planar bed. This groundwater induced hyporheic zone expansion could increase the potential for biogeochemical cycling and natural attenuation. © 2015, National Ground Water Association.

Using Bayesian Network as a tool for coastal storm flood impact prediction at Varna Bay (Bulgaria, Western Black Sea)

NASA Astrophysics Data System (ADS)

Valchev, Nikolay; Eftimova, Petya; Andreeva, Nataliya; Prodanov, Bogdan

2017-04-01

Coastal zone is among the fastest evolving areas worldwide. Ever increasing population inhabiting coastal settlements develops often conflicting economic and societal activities. The existing imbalance between the expansion of these activities, on one hand, and the potential to accommodate them in a sustainable manner, on the other, becomes a critical problem. Concurrently, coasts are affected by various hydro-meteorological phenomena such as storm surges, heavy seas, strong winds and flash floods, which intensities and occurrence frequency is likely to increase due to the climate change. This implies elaboration of tools capable of quick prediction of impact of those phenomena on the coast and providing solutions in terms of disaster risk reduction measures. One such tool is Bayesian network. Proposed paper describes the set-up of such network for Varna Bay (Bulgaria, Western Black Sea). It relates near-shore storm conditions to their onshore flood potential and ultimately to relevant impact as relative damage on coastal and manmade environment. Methodology for set-up and training of the Bayesian network was developed within RISC-KIT project (Resilience-Increasing Strategies for Coasts - toolKIT). Proposed BN reflects the interaction between boundary conditions, receptors, hazard, and consequences. Storm boundary conditions - maximum significant wave height and peak surge level, were determined on the basis of their historical and projected occurrence. The only hazard considered in this study is flooding characterized by maximum inundation depth. BN was trained with synthetic events created by combining estimated boundary conditions. Flood impact was modeled with the process-based morphodynamical model XBeach. Restaurants, sport and leisure facilities, administrative buildings, and car parks were introduced in the network as receptors. Consequences (impact) are estimated in terms of relative damage caused by given inundation depth. National depth-damage (susceptibility) curves were used to define the percentage of damage ranked as low, moderate, high and very high. Besides previously described components, BN includes also two hazard influencing disaster risk reduction (DRR) measures: re-enforced embankment of Varna Port wall and beach nourishment. As a result of training process the network is able to evaluate spatially varying hazards and damages for specific storm conditions. Moreover, it is able to predict where on the site the highest impact would occur and to quantify the mitigation capacity of proposed DRR measures. For example, it is estimated that storm impact would be considerably reduced in present conditions but vulnerability would be still high in climate change perspective.

Revised forecast: Another stormy summer ahead

NASA Astrophysics Data System (ADS)

Carlowicz, Michael

After predicting in November 1995 that the 1996 hurricane season would be less active than the typical year (Eos, December 12, 1995), William Gray and his colleagues from Colorado State University have revised their forecast. Plugging updated atmospheric data into their statistical model, the researchers are now predicting seven hurricanes—two of them intense (category 3, 4, or 5)—and 11 named storms for the summer and fall of 1996. Net tropical cyclone activity for the hurricane season, which lasts from June 1 to December 1, should be 105% of the 25-year average, according to Gray.In November, Gray and Chris Landsea of NOAA's Hurricane Research Division predicted eight tropical storms and five hurricanes (two intense), less than the historical averages of 9.3 named storms and 5.7 hurricanes per season. The change in expectations is the result of new accounting for trends in temperature and barometric pressure in Africa and around the Atlantic Basin.

Seasonal variations of snow depth on Mars.

PubMed

Smith, D E; Zuber, M T; Neumann, G A

2001-12-07

Using topography collected over one martian year from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor (MGS) spacecraft, we have measured temporal changes in the elevation of the martian surface that correlate with the seasonal cycle of carbon dioxide exchange between the surface and atmosphere. The greatest elevation change (1.5 to 2 meters) occurs at high latitudes ( above 80 degrees ), whereas the bulk of the mass exchange occurs at lower latitudes (below 75 degrees N and below 73 degrees S). An unexpected period of sublimation was observed during northern hemisphere autumn, coincident with dust storms in the southern hemisphere. Analysis of MGS Doppler tracking residuals revealed temporal variations in the flattening of Mars that correlate with elevation changes. The combined changes in gravity and elevation constrain the average density of seasonally deposited carbon dioxide to be 910 +/- 230 kilograms per cubic meter, which is considerably denser than terrestrial snow.

Factors affecting large peakflows on Appalachian watersheds: lessons from the Fernow Experimental Forest

Treesearch

James N. Kochenderfer; Mary Beth Adams; Gary W. Miller; David J. Helvey

2007-01-01

Data collected since 1951 on the Fernow Experimental Forest near Parsons, West Virginia, and at a gaging station on the nearby Cheat River since 1913 were used to evaluate factors affecting large peakflows on forested watersheds. Treatments ranged from periodic partial cuts to complete deforestation using herbicides. Total storm precipitation and average storm...

Lightning Evolution In Two North Central Florida Summer Multicell Storms and Three Winter/Spring Frontal Storms

NASA Astrophysics Data System (ADS)

Caicedo, J. A.; Uman, M. A.; Pilkey, J. T.

2018-01-01

We present the first lightning evolution studies, via the Lightning Mapping Array (LMA) and radar, performed in North Central Florida. Parts of three winter/spring frontal storms (cold season) and two complete summer (warm season) multicell storms are studied. Storm parameters measured are as follows: total number of flashes, flash-type classification, first flashes, flash initiation altitude, flash initiation power, flash rate (flashes per minute), charge structure, altitude and temperature ranges of the inferred charge regions, atmospheric isotherm altitude, radar base reflectivity (dBZ), and radar echo tops (EET). Several differences were found between summer multicell and winter/spring frontal storms in North Central Florida: (1) in winter/spring storms, the range of altitudes that all charge regions occupy is up to 1 km lower in altitude than in summer storms, as are the 0°C, -10°C, and -20°C isotherms; (2) lightning activity in summer storms is highly correlated with changes in radar signatures, in particular, echo tops; and (3) the LMA average initiation power of all flash types in winter/frontal storms is about an order of magnitude larger than that for summer storms. In relation to storms in other geographical locations, North Central Florida seasonal storms were found to have similarities in most parameters studied with a few differences, examples in Florida being (1) colder initiation altitudes for intracloud flashes, (2) charge regions occupying larger ranges of atmospheric temperatures, and (3) winter/spring frontal storms not having much lightning activity in the stratiform region.

Vertical suspsended sediment fluxes observed from ocean gliders

NASA Astrophysics Data System (ADS)

Merckelbach, Lucas; Carpenter, Jeffrey

2016-04-01

Many studies trying to understand a coastal system in terms of sediment transport paths resort to numerical modelling - combining circulation models with sediment transport models. Two aspects herein are crucial: sediment fluxes across the sea bed-water column interface, and the subsequent vertical mixing by turbulence. Both aspects are highly complex and have relatively short time scales, so that the processes involved are implemented in numerical models as parameterisations. Due to the effort required to obtain field observations of suspended sediment concentrations (and other parameters), measurements are scarce, which makes the development and tuning of parameterisations a difficult task. Ocean gliders (autonomous underwater vehicles propelled by a buoyancy engine) provide a platform complementing more traditional methods of sampling. In this work we present observations of suspended sediment concentration (SSC) and dissipation rate taken by two gliders, each equipped with optical sensors and a microstructure sensor, along with current observations from a bottom mounted ADCP, all operated in the German Bight sector of the North Sea in Summer 2014. For about two weeks of a four-week experiment, the gliders were programmed to fly in a novel way as Lagrangian profilers to water depths of about 40 m. The benefit of this approach is that the rate of change of SSC - and other parameters - is local to the water column, as opposed to an unknown composition of temporal and spatial variability when gliders are operated in the usual way. Therefore, vertical sediment fluxes can be calculated without the need of the - often dubious - assumption that spatial variability can be neglected. During the experiment the water column was initially thermally stratified, with a cross-pycnocline diffusion coefficient estimated at 7\\cdot10-5 m2 s-1. Halfway through the experiment the remnants of tropical storm Bertha arrived at the study site and caused a complete mixing of the water column. An analysis of the data showed that resuspension and deposition were solely tidally-driven and in equilibrium prior to the arrival of the storm, with an averaged resuspension rate of 3-4 g m-2 s-1. During the storm the effect of surface waves increased the resuspension rate by an order of magnitude. The data suggest that after the passing of the storm, when the tide was the main driver again, resuspension rates are generally higher than before the storm. This provides a further indication that although a (Summer) storm might be a short-term event, its effects on sediment transport may be felt on much longer time scales.

A two-parameter design storm for Mediterranean convective rainfall

NASA Astrophysics Data System (ADS)

García-Bartual, Rafael; Andrés-Doménech, Ignacio

2017-05-01

The following research explores the feasibility of building effective design storms for extreme hydrological regimes, such as the one which characterizes the rainfall regime of the east and south-east of the Iberian Peninsula, without employing intensity-duration-frequency (IDF) curves as a starting point. Nowadays, after decades of functioning hydrological automatic networks, there is an abundance of high-resolution rainfall data with a reasonable statistic representation, which enable the direct research of temporal patterns and inner structures of rainfall events at a given geographic location, with the aim of establishing a statistical synthesis directly based on those observed patterns. The authors propose a temporal design storm defined in analytical terms, through a two-parameter gamma-type function. The two parameters are directly estimated from 73 independent storms identified from rainfall records of high temporal resolution in Valencia (Spain). All the relevant analytical properties derived from that function are developed in order to use this storm in real applications. In particular, in order to assign a probability to the design storm (return period), an auxiliary variable combining maximum intensity and total cumulated rainfall is introduced. As a result, for a given return period, a set of three storms with different duration, depth and peak intensity are defined. The consistency of the results is verified by means of comparison with the classic method of alternating blocks based on an IDF curve, for the above mentioned study case.

Contribution of dust storms to PM10 levels in an urban arid environment.

PubMed

Krasnov, Helena; Katra, Itzhak; Koutrakis, Petros; Friger, Michael D

2014-01-01

Quantitative information on the contribution of dust storms to atmospheric PM10 (particulate matter with an aerodynamic diameter < or = 10 microm) levels is still lacking, especially in urban environments with close proximity to dust sources. The main objective of this study was to quantify the contribution of dust storms to PM10 concentrations in a desert urban center, the city of Beer-Sheva, Negev, Israel, during the period of 2001-2012. Toward this end, a background value based on the "dust-free" season was used as a threshold value to identify potentially "dust days." Subsequently, the net contribution of dust storms to PM10 was assessed. During the study period, daily PM10 concentrations ranged from 6 to over 2000 microg/m3. In each year, over 10% of the daily concentrations exceeded the calculated threshold (BVt) of 71 microg/m3. An average daily net contribution of dust to PM10 of 122 microg/m3 was calculated for the entire study period based on this background value. Furthermore, a dust storm intensity parameter (Ai) was used to analyze several storms with very high PM10 contributions (hourly averages of 1000-5197 microg/m3). This analysis revealed that the strongest storms occurred mainly in the last 3 yr of the study. Finally, these findings indicate that this arid urban environment experiences high PM10 levels whose origin lies in both local and regional dust events. The findings indicate that over time, the urban arid environment experiences high PM10 levels whose origin lies in local and regional dust events. It was noticed that the strongest storms have occurred mainly in the last 3 yr. It is believed that environmental changes such as global warming and desertification may lead to an increased air pollution and risk exposure to human health.

Progress in the Study of Coastal Storm Deposits

NASA Astrophysics Data System (ADS)

Xiong, Haixian; Huang, Guangqing; Fu, Shuqing; Qian, Peng

2018-05-01

Numerous studies have been carried out to identify storm deposits and decipher storm-induced sedimentary processes in coastal and shallow-marine areas. This study aims to provide an in-depth review on the study of coastal storm deposits from the following five aspects. 1) The formation of storm deposits is a function of hydrodynamic and sedimentary processes under the constraints of local geological and ecological factors. Many questions remain to demonstrate the genetic links between storm-related processes and a variety of resulting deposits such as overwash deposits, underwater deposits and hummocky cross-stratification (HCS). Future research into the formation of storm deposits should combine flume experiments, field observations and numerical simulations, and make full use of sediment source tracing methods. 2) Recently there has been rapid growth in the number of studies utilizing sediment provenance analysis to investigate the source of storm deposits. The development of source tracing techniques, such as mineral composition, magnetic susceptibility, microfossil and geochemical property, has allowed for better understanding of the depositional processes and environmental changes associated with coastal storms. 3) The role of extreme storms in the sedimentation of low-lying coastal wetlands with diverse ecosystem services has also drawn a great deal of attention. Many investigations have attempted to quantify widespread land loss, vertical marsh sediment accumulation and wetland elevation change induced by major hurricanes. 4) Paleostorm reconstructions based on storm sedimentary proxies have shown many advantages over the instrumental records and historic documents as they allow for the reconstruction of storm activities on millennial or longer time scales. Storm deposits having been used to establish proxies mainly include beach ridges and shelly cheniers, coral reefs, estuary-deltaic storm sequences and overwash deposits. Particularly over the past few decades, the proxies developed from overwash deposits have successfully retrieved many records of storm activities during the mid to late Holocene worldwide. 5) Distinguishing sediments deposited by storms and tsunamis is one of the most difficult issues among the many aspects of storm deposit studies. Comparative studies have investigated numerous diagnostic evidences including hydrodynamic condition, landward extent, grain property, texture and grading, thickness, microfossil assemblage and landscape conformity. Perhaps integrating physical, biological and geochemical evidences will, in the future, allow unambiguous identification of tsunami deposits and storm deposits.

Major winter and nonwinter floods in selected basins in New York and Pennsylvania

USGS Publications Warehouse

Langbein, Walter Basil

1947-01-01

The scientific design of flood-control works is based on an evaluation of the hydrologic factors basic to flood events, particularly how rainfall and snow runoff, soil conditions, and channel influences can combine to produce greater or lesser floods. For this purpose an analysis of the pertinent hydrologic data is needed. The methods of analysis adopted should conform as closely as possible to those already in use and must be adapted to the quality of the available information. Maximum floods in 8 basins in New York and Pennsylvania during the winter and nonwinter months were studied, a total of 21 floods. The most outstanding winter flood of record in the North Atlantic region was that of March 1936. Rainfall plus snow melt in the basins studied ranged between 3.04 and 6.87 inches, and associated volumes of direct runoff from 1.88 to 5.63 inches. Winter floods have a common characteristic in their relation to freezing temperature. The antecedent periods, representing a period of snow accumulation and frost penetration, are below freezing, and the flood itself is contemporaneous with a period of above-freezing temperatures, usually associated with rain, during which the previously accumulated snow is melted. A second common characteristic of major winter floods is their tendency to be associated with widespread causal meteorologic conditions. There was a more complete conversion of rainfall and snow melt into runoff during the winter storms studied than during the wettest nonwinter flood. Snow melt during winter floods ranged from 0.04 to 0.07 inch per degree-day above 32° F. The depth of mean areal rainfall produced by the nonwinter storms studied ranged from 3.05 to 4.96 inches. The maximum 24-hour quantity at single stations was 14 inches, which was measured during the storm of July 1935 in New York. The volume of direct runoff ranged between 1.39 and 3.41 inches. The portion of rainfall that was converted into runoff varied in accordance with the rate of antecedent base flow, expressed in second-feet per square mile, and emphasized the influence of antecedent conditions. The average volume of direct runoff during winter floods was 4.24 inches, and the average during nonwinter floods was 2.44 inches. The latter, however, were more concentrated as to time, tending to compensate for large volume of runoff in winter, so that the crest rates of direct runoff averaged 0.056 inches per hour during the winter and 0.051 inches during the nonwinter period.

Diazinon and chlorpyrifos loads in precipitation and urban and agricultural storm runoff during January and February 2001 in the San Joaquin River basin, California

USGS Publications Warehouse

Zamora, Celia; Kratzer, Charles R.; Majewski, Michael S.; Knifong, Donna L.

2003-01-01

The application of diazinon and chlorpyrifos on dormant orchards in 2001 in the San Joaquin River Basin was 24 percent less and 3.2 times more than applications in 2000, respectively. A total of 16 sites were sampled during January and February 2001 storm events: 7 river sites, 8 precipitation sites, and 1 urban storm drain. The seven river sites were sampled weekly during nonstorm periods and more frequently during storm runoff from a total of four storms. The monitoring of storm runoff at a city storm drain in Modesto, California, occurred simultaneously with the collection of precipitation samples from eight sites during a January 2001 storm event. The highest concentrations of diazinon occurred during the storm periods for all 16 sites, and the highest concentrations of chlorpyrifos occurred during weekly nonstorm sampling for the river sites and during the January storm period for the urban storm drain and precipitation sites. A total of 60 samples (41 from river sites, 10 from precipitation sites, and 9 from the storm drain site) had diazinon concentrations greater than 0.08 ?g/L, the concentration being considered by the California Department of Fish and Game as its criterion maximum concentration for the protection of aquatic habitats. A total of 18 samples (2 from river sites, 9 from precipitation sites, and 7 from the storm drain site) exceeded the equivalent California Department of Fish and Game guideline of 0.02 ?g/L for chlorpyrifos. The total diazinon load in the San Joaquin River near Vernalis during January and February 2001 was 23.8 pounds active ingredient; of this amount, 16.9 pounds active ingredient were transported by four storms, 1.06 pounds active ingredient were transported by nonstorm events, and 5.82 pounds active ingredient were considered to be baseline loads. The total chlorpyrifos load in the San Joaquin River near Vernalis during January and February 2001 was 2.17 pounds active ingredient; of this amount, 0.702 pound active ingredient was transported during the four storms, and 1.47 pounds active ingredient were considered as baseline load. The total January and February diazinon load in the San Joaquin River near Vernalis was 0.27 percent of dormant application; the total January and February chlorpyrifos load was 0.02 percent of dormant application. The precipitation samples collected during the January 2001 storm event were analyzed for pesticides to evaluate their potential contribution to pesticide loads in the study area. When the average concentrations of diazinon and chlorpyrifos in the precipitation samples were compared with concentrations in urban storm runoff samples, 68 percent of the diazinon concentration in the runoff could be accounted for in the precipitation. Chlorpyrifos, however, had average precipitation concentrations that were 2.5 times higher than what was detected in the runoff. Although no firm conclusions can be made from one storm event, preliminary results indicate that pesticides in precipitation can significantly contribute to pesticide loads in storm runoff.

Nighttime atmospheric stability changes and their effects on the temporal intensity of a mesoscale convective complex

NASA Technical Reports Server (NTRS)

Hovis, Jeffrey S.; Brundidge, Kenneth C.

1987-01-01

A method of interpolating atmospheric soundings while reducing the errors associated with simple time interpolation was developed. The purpose of this was to provide a means to determine atmospheric stability at times between standard soundings and to relate changes in stability to intensity changes in an MCC. Four MCC cases were chosen for study with this method with four stability indices being included. The discussion centers on three aspects for each stability parameter examined: the stability field in the vicinity of the storm and its changes in structure and magnitude during the lifetime of the storm, the average stability within the storm boundary as a function of time and its relation to storm intensity, and the apparent flux of stability parameter into the storm as a consequence of low-level storm relative flow. It was found that the results differed among the four stability parameters, sometimes in a conflicting fashion. Thus, an interpolation of how the storm intensity is related to the changing environmental stability depends upon the particular index utilized. Some explanation for this problem is offered.

Stalling Tropical Cyclones over the Atlantic Basin

NASA Astrophysics Data System (ADS)

Nielsen-Gammon, J. W.; Emanuel, K.

2017-12-01

Hurricane Harvey produced massive amounts of rain over southeast Texas and southwest Louisiana. Average storm total rainfall amounts over a 10,000 square mile (26,000 square km) area exceeded 30 inches (750 mm). An important aspect of the storm that contributed to the large rainfall totals was its unusual motion. The storm stalled shortly after making landfall, then moved back offshore before once again making landfall five days later. This storm motion permitted heavy rainfall to occur in the same general area for an extended period of time. The unusual nature of this event motivates an investigation into the characteristics and potential climate change influences on stalled tropical cyclones in the Atlantic basin using the HURDAT 2 storm track database for 1866-2016 and downscaled tropical cyclones driven by simulations of present and future climate. The motion of cyclones is quantified as the size of a circle circumscribing all storm locations during a given length of time. For a three-day period, Harvey remained inside a circle with a radius of 123 km. This ranks within the top 0.6% of slowest-moving historical storm instances. Among the 2% of slowest-moving storm instances prior to Harvey, only 13 involved storms that stalled near the continental United States coast, where they may have produced substantial rainfall onshore while tapping into marine moisture. Only two such storms stalled in the month of September, in contrast to 20 September stalls out of the 36 storms that stalled over the nearby open Atlantic. Just four of the stalled coastal storms were hurricanes, implying a return frequency for such storms of much less than once per decade. The synoptic setting of these storms is examined for common features, and historical and projected trends in occurrences of stalled storms near the coast and farther offshore are investigated.

The radioactivity of seasonal dust storms in the Middle East: the May 2012 case study in Jordan.

PubMed

Hamadneh, Hamed S; Ababneh, Zaid Q; Hamasha, Khadeejeh M; Ababneh, Anas M

2015-02-01

Dust storms in the Middle East are common during spring. Some of these storms are massive and carry a large amount of dust from faraway regions, which pose health and pollution risks. The huge dust storm event occurred in early May, 2012 was investigated for its radioactive content using gamma ray spectroscopy. Dust samples were collected from Northern Jordan and it was found that the storm carried a large amount of both artificial and natural radioactivity. The average activity concentration of fallout (137)Cs was 17.0 Bq/kg which is larger than that found in soil (2.3 Bq/kg), and this enrichment is attributed to particle size effects. (7)Be which is of atmospheric origin and has a relatively short half-life, was detected in dust with relatively large activity concentrations, as it would be expected, with an average of 2860 Bq/kg, but it was not detected in soil. Despite the large activity concentration of (7)Be, dose assessment showed that it does not contribute significantly to the effective dose through inhalation. The concentrations of the primodial nuclides (40)K, (232)Th and (238)U were 547, 30.0 and 49.3 Bq/kg, respectively. With the exception of (40)K, these were comparable to what was found in soil. Copyright © 2014 Elsevier Ltd. All rights reserved.

Representation of Stormflow and a More Responsive Water Table in a TOPMODEL-Based Hydrology Model

NASA Technical Reports Server (NTRS)

Shaman, Jeffrey; Stieglitz, Marc; Engel, Victor; Koster, Randal; Stark, Colin; Houser, Paul R. (Technical Monitor)

2001-01-01

This study presents two new modeling strategies. First, a methodology for representing the physical process of stormflow within a TOPMODEL framework is developed. In using this approach, discharge at quickflow time scales is simulated and a fuller depiction of hydrologic activity is brought about. Discharge of water from the vadose zone is permitted in a physically realistic manner without a priori assumption of the level within the soil column at which stormflow saturation can take place. Determination of the stormflow contribution to discharge is made using the equation for groundwater flow. No new parameters are needed. Instead, regions of near saturation that develop during storm events, producing vertical recharge, are allowed to contribute to soil column discharge. These stormflow contributions to river runoff, as for groundwater flow contributions, are a function of catchment topography and local hydraulic conductivity at the depth of these regions of near saturation. The second approach improves groundwater flow response through a reduction of porosity and field capacity with depth in the soil column. Large storm events are better captured and a more dynamic water table develops with application of this modified soil column profile (MSCP). The MSCP predominantly reflects soil depth differences in upland and lowland regions of a watershed. Combined, these two approaches - stormflow and the MSCP - provide a more accurate representation of the time scales at which soil column discharge responds and a more complete depiction of hydrologic activity. Storm events large and small are better simulated, and some of the biases previously evident in TOPMODEL simulations are reduced.

A matter of scale: damage from Hurricane Hugo (1989) to U.S. Virgin Islands reefs at the colony, community and whole reef level

USGS Publications Warehouse

Rogers, Caroline S.

1993-01-01

Studies at Buck Island Reef National Monument (St. Croix) and Virgin Islands National Park (St. John) by scientists in the U.S. National Park Service Coral Reef Assessment Program re- vealed the effects of Humcane Hugo on individual coral species, community parameters, and overall reef structure. Effects of the storm varied with depth, coral species, location relative to the storm path, character of the pre-storm communities, and ecological history. Live coral cover, initially less than 30% at all sites, dropped by 40 to 73%. Cover by the dominant species Montastrea annularis de- clined about 35% on the St. John reefs. At Buck Island, Acropora palmata cover, already reduced from 85% to 5% by white band disease and storms, fell to 0.8% after Hugo. Some areas on the south side of Buck Island were reduced to rubble pave- ment while other areas escaped serious damage. Data from cores at Buck Island reveal the influence of wave energy and storm frequency on overall reef character. Patchiness and variation in the responses of different species, zones, and entire reefs to the storm suggest that assessment of long-term trends in reef structure and composition requires analysis of changes at permanent study sites distributed over large areas.

Storm impacts upon the composition of organic matrices in Nagara River--a study based on molecular weight and activated carbon adsorbability.

PubMed

Li, Fusheng; Yuasa, Akira; Chiharada, Hajime; Matsui, Yoshihiko

2003-09-01

The impacts of a heavy storm of rain on the composition of natural organic matter (NOM) in Nagara River water were studied in terms of molecular weights (MWs) and activated carbon (AC) adsorbabilities using six water samples collected during a critical Typhoon weather condition. The composition in MWs was analyzed using a HPSEC system and that in adsorbabilities was characterized using parameters devised to reflect NOMs average adsorptive strength (K(M)), adsorptive strength polydispersity (sigma), affinity to AC (1/n) and non-adsorbable fraction (C(non)/C(T0)), respectively. These parameters were determined by model description of observed isotherms with a distributed fictive component method. The heavy storm of rain brought higher content of larger organic components into the river source, thus causing changes of NOMs weight-averaged MWs in the range of 2962-3495 Dalton and MW polydispersity in the narrow range of 1.153-1.226. Comparison of K(M) and sigma values for all samples assessed with both indices of TOC and UV260 showed that large proportions of the storm-induced organic components had adsorptive strengths similar to those existent before the storm, with the presence levels for components revealing much strong and weak adsorbabilities being low. Among all organic components brought into the river by the storm of rain, the percentages of non-adsorbable ones was lower (smaller C(non)/C(T0) values); and the adsorbable ones had generally more affinity to the adsorbents used (smaller 1/n values).

The case for a southeastern Australian Dust Bowl, 1895-1945

NASA Astrophysics Data System (ADS)

Cattle, Stephen R.

2016-06-01

Australia has an anecdotal history of severe wind erosion and dust storm activity, but there has been no lasting public perception of periods of extreme dust storm activity in this country, such as that developed in the USA following the Dust Bowl of the 1930s. Newspaper accounts of droughts and dust storms in southeastern (SE) Australia between 1895 and 1945 suggest that, at various times, the scale of these events was comparable to those experienced in the USA Dust Bowl. During this 50-year period, average annual rainfall values in this region were substantially below long-term averages, air temperatures were distinctly warmer, marginal lands were actively cropped and grazed, and rabbits were a burgeoning grazing pest. From the beginning of the Federation Drought of 1895-1902, dust storm activity increased markedly, with the downwind coastal cities of Sydney and Melbourne experiencing dust hazes, dust storms and falls of red rain relatively regularly. Between 1935 and 1945, Sydney and Melbourne received ten and nine long-distance dust events, respectively, with the years of 1938 and 1944/45 being the most intensely dusty. Entire topsoil horizons were blown away, sand drift was extreme, and crops and sheep flocks were destroyed. Although these periods of extreme dust storm activity were not as sustained as those experienced in the USA in the mid-1930s, there is a strong case to support the contention that SE Australia experienced its own extended, somewhat episodic version of a Dust Bowl, with a similar combination of causal factors and landscape effects.

Observations of Morphodynamics During a Winter Storm at the Mouth of the Misa River

NASA Astrophysics Data System (ADS)

Calantoni, J.; Sheremet, A.; Brocchini, M.; Postacchini, M.

2016-02-01

The shallow mouth of the Misa River, Senigallia, Italy is exposed to wind and waves from the Adriatic Sea and is vulnerable to morphodynamic activity during even moderate storm events. Sediment loads and transport patterns may be strongly influenced by the confluence of fine cohesive suspended sediment contained in the discharge from the river mixing with coarser sandy material stirred up by waves impinging on the river mouth. Observations of rapid changes in bed elevation along a transect extending offshore of the river mouth were made using a combination of instruments deployed from 23-27 January 2014 at two locations in roughly 5 m water depth and 6 m water depth. Additionally, an up looking ADCP was located farther offshore in approximately 7 m water depth. The deposited sediment quickly consolidated into a hardened mixture of sand, mud, and venerids over the base of our instrument frames. At the 5 m water depth location over 0.4 m of deposition was observed roughly during a 6-hour period. Similarly, at the 6 m water depth location nearly 0.2 m of deposition was observed roughly over a 6-hour period with approximately a two-hour time lag. The onset of deposition was concurrent with a change in direction of the mean currents at both locations and a change in direction of wave skewness observed at the 5 m water depth location. We hypothesize that sandbar migration was responsible for the observed changes in bed elevation at both locations. Our analysis will focus on sediment transport modeling to explain rates of deposition and time lag of the observed changes in bed elevation at the 5 m and 6 m water depth locations.

Shallow subsurface storm flow in a forested headwater catchment: Observations and modeling using a modified TOPMODEL

USGS Publications Warehouse

Scanlon, Todd M.; Raffensperger, Jeff P.; Hornberger, George M.; Clapp, Roger B.

2000-01-01

Transient, perched water tables in the shallow subsurface are observed at the South Fork Brokenback Run catchment in Shenandoah National Park, Virginia. Crest piezometers installed along a hillslope transect show that the development of saturated conditions in the upper 1.5 m of the subsurface is controlled by total precipitation and antecedent conditions, not precipitation intensity, although soil heterogeneities strongly influence local response. The macroporous subsurface storm flow zone provides a hydrological pathway for rapid runoff generation apart from the underlying groundwater zone, a conceptualization supported by the two‐storage system exhibited by hydrograph recession analysis. A modified version of TOPMODEL is used to simulate the observed catchment dynamics. In this model, generalized topographic index theory is applied to the subsurface storm flow zone to account for logarithmic storm flow recessions, indicative of linearly decreasing transmissivity with depth. Vertical drainage to the groundwater zone is required, and both subsurface reservoirs are considered to contribute to surface saturation.

Bounce- and MLT-averaged diffusion coefficients in a physics-based magnetic field geometry obtained from RAM-SCB for the March 17 2013 storm

DOE PAGES

Zhao, Lei; Yu, Yiqun; Delzanno, Gian Luca; ...

2015-04-01

Local acceleration via whistler wave and particle interaction plays a significant role in particle dynamics in the radiation belt. In this work we explore gyro-resonant wave-particle interaction and quasi-linear diffusion in different magnetic field configurations related to the March 17 2013 storm. We consider the Earth's magnetic dipole field as a reference and compare the results against non-dipole field configurations corresponding to quiet and stormy conditions. The latter are obtained with the ring current-atmosphere interactions model with a self-consistent magnetic field RAM-SCB, a code that models the Earth's ring current and provides a realistic modeling of the Earth's magnetic field.more » By applying quasi-linear theory, the bounce- and MLT-averaged electron pitch angle, mixed term, and energy diffusion coefficients are calculated for each magnetic field configuration. For radiation belt (~1 MeV) and ring current (~100 keV) electrons, it is shown that at some MLTs the bounce-averaged diffusion coefficients become rather insensitive to the details of the magnetic field configuration, while at other MLTs storm conditions can expand the range of equatorial pitch angles where gyro-resonant diffusion occurs and significantly enhance the diffusion rates. When MLT average is performed at drift shell L = 4.25 (a good approximation to drift average), the diffusion coefficients become quite independent of the magnetic field configuration for relativistic electrons, while the opposite is true for lower energy electrons. These results suggest that, at least for the March 17 2013 storm and for L ≲ 4.25, the commonly adopted dipole approximation of the Earth's magnetic field can be safely used for radiation belt electrons, while a realistic modeling of the magnetic field configuration is necessary to describe adequately the diffusion rates of ring current electrons.« less

Bounce- and MLT-averaged diffusion coefficients in a physics-based magnetic field geometry obtained from RAM-SCB for the March 17 2013 storm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Lei; Yu, Yiqun; Delzanno, Gian Luca

Local acceleration via whistler wave and particle interaction plays a significant role in particle dynamics in the radiation belt. In this work we explore gyro-resonant wave-particle interaction and quasi-linear diffusion in different magnetic field configurations related to the March 17 2013 storm. We consider the Earth's magnetic dipole field as a reference and compare the results against non-dipole field configurations corresponding to quiet and stormy conditions. The latter are obtained with the ring current-atmosphere interactions model with a self-consistent magnetic field RAM-SCB, a code that models the Earth's ring current and provides a realistic modeling of the Earth's magnetic field.more » By applying quasi-linear theory, the bounce- and MLT-averaged electron pitch angle, mixed term, and energy diffusion coefficients are calculated for each magnetic field configuration. For radiation belt (~1 MeV) and ring current (~100 keV) electrons, it is shown that at some MLTs the bounce-averaged diffusion coefficients become rather insensitive to the details of the magnetic field configuration, while at other MLTs storm conditions can expand the range of equatorial pitch angles where gyro-resonant diffusion occurs and significantly enhance the diffusion rates. When MLT average is performed at drift shell L = 4.25 (a good approximation to drift average), the diffusion coefficients become quite independent of the magnetic field configuration for relativistic electrons, while the opposite is true for lower energy electrons. These results suggest that, at least for the March 17 2013 storm and for L ≲ 4.25, the commonly adopted dipole approximation of the Earth's magnetic field can be safely used for radiation belt electrons, while a realistic modeling of the magnetic field configuration is necessary to describe adequately the diffusion rates of ring current electrons.« less

The effects of Hurricane Hugo on suspended-sediment loads, Lago Loiza Basin, Puerto Rico

USGS Publications Warehouse

Gellis, A.

1993-01-01

In the two main tributaries that enter Lago Loiza, Rio Grande de Loiza and Rio Gurabo, 99 600 tonnes of suspended sediment was transported by 58.2??106 m3 of runoff in a 48 h period. The storm-average suspended-sediment concentration in the Rio Grande de Loiza for Hurricane Hugo was 2290 mgl-1, the second lowest for the 12 storms that have been monitored at this site. In Rio Gurabo the storm-average suspended-sediment concentration was 1420 mg l -1, the sixth lowest recorded out of 15 monitored storms. In Quebrada Salvatierra, a small tributary to Rio Grande de Loiza, suspended-sediment concentrations were as low as 33 mg l-1 during peak runoff of 20m3s-1. Normally the suspended-sediment concentrations at this discharge are 300 mg l-1. Hurricane force winds seem to be the most important factor contributing to the lower than expected suspended-sediment loads. High winds caused vegetation and debris to be dislodged and displaced. Debris accumulated on hillslopes and in small channels, blocked bridges and formed debris dams. These dams caused local backwater effects that reduced stream velocities and decreased suspended-sediment loads. -from Author

Intra-storm variability in microbial partitioning and microbial loading rates.

PubMed

Krometis, Leigh-Anne H; Characklis, Gregory W; Simmons, Otto D; Dilts, Mackenzie J; Likirdopulos, Christina A; Sobsey, Mark D

2007-01-01

Association with particles in the water column can have a significant impact on microbial fate and transport. This study analyzed multiple stormwater samples taken throughout the duration of three separate storms (at two different sites) to evaluate the fraction of microbes partitioning to denser "settleable" particles and to examine how partitioning behavior varied over the course of a storm. Intra-storm sampling also allowed for estimates of microbial loading rates (both total and particle-associated) and cumulative storm-induced microbial load. Five different indicator organisms were examined, with the fraction of microbes associated with settleable particles assessed via a calibrated centrifugation method. Partitioning behavior varied across microorganism type, with an average of 40% of fecal coliforms, Escherichia coli, and enterococci associating with settleable particles, compared to approximately 65% of Clostridium perfringens spores and only 13% of total coliphage. Partitioning remained fairly constant for each type of organism throughout storm events. Nonetheless, higher concentrations of both settleable particles and microbes entering the water column soon after the onset of a storm led to higher loading rates of settleable microbes in the storm's earliest stages, a trend that could have important implications for the design of stormwater management structures (e.g., detention basins). Estimates of cumulative storm-induced microbial loading suggested that one day's worth of storm loading can be the equivalent of months, or even years, of dry-weather loading.

On the Reduced Geoeffectiveness of Solar Cycle 24: A Moderate Storm Perspective

NASA Technical Reports Server (NTRS)

Selvakumaran, R.; Veenadhari, B.; Akiyama, S.; Pandya, Megha; Gopalswamy, N,; Yashiro, S.; Kumar, Sandeep; Makela, P.; Xie, H.

2016-01-01

The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (epsilon) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.

Prominent November Coldwaves in the North Central United States Since 1901.

NASA Astrophysics Data System (ADS)

Wendland, Wayne M.

1987-06-01

The frequency and intensity of early winter (November) coldwaves were investigated for the north central United States. Twenty-two such storms occurred from 1901 to 1985, and were most frequent in the 1950s and early 1960s, and again from the mid 1970s to the present.November coldwaves are most often the result of Colorado cyclones moving to the cast northeast. On average, temperature declines of 22°C or more within 24 hours, falling to at least 0°C, impacted about 40 percent of the 12-state region. The storms were most often accompanied by strong winds, wind chill, heavy snow to the west, and thunderstorms to the cast, i.e., the trappings of a severe winter storm. Many of these storms inflicted severe damage on land and on the Great Lakes, sometimes taking lives of those not anticipating such a severe "winter" storm in November.

Depth-Duration Frequency of Precipitation for Oklahoma

USGS Publications Warehouse

Tortorelli, Robert L.; Rea, Alan; Asquith, William H.

1999-01-01

A regional frequency analysis was conducted to estimate the depth-duration frequency of precipitation for 12 durations in Oklahoma (15, 30, and 60 minutes; 1, 2, 3, 6, 12, and 24 hours; and 1, 3, and 7 days). Seven selected frequencies, expressed as recurrence intervals, were investigated (2, 5, 10, 25, 50, 100, and 500 years). L-moment statistics were used to summarize depth-duration data and to determine the appropriate statistical distributions. Three different rain-gage networks provided the data (15minute, 1-hour, and 1-day). The 60-minute, and 1-hour; and the 24-hour, and 1-day durations were analyzed separately. Data were used from rain-gage stations with at least 10-years of record and within Oklahoma or about 50 kilometers into bordering states. Precipitation annual maxima (depths) were determined from the data for 110 15-minute, 141 hourly, and 413 daily stations. The L-moment statistics for depths for all durations were calculated for each station using unbiased L-mo-ment estimators for the mean, L-scale, L-coefficient of variation, L-skew, and L-kur-tosis. The relation between L-skew and L-kurtosis (L-moment ratio diagram) and goodness-of-fit measures were used to select the frequency distributions. The three-parameter generalized logistic distribution was selected to model the frequencies of 15-, 30-, and 60-minute annual maxima; and the three-parameter generalized extreme-value distribution was selected to model the frequencies of 1-hour to 7-day annual maxima. The mean for each station and duration was corrected for the bias associated with fixed interval recording of precipitation amounts. The L-scale and spatially averaged L-skew statistics were used to compute the location, scale, and shape parameters of the selected distribution for each station and duration. The three parameters were used to calculate the depth-duration-frequency relations for each station. The precipitation depths for selected frequencies were contoured from weighted depth surfaces to produce maps from which the precipitation depth-duration-frequency curve for selected storm durations can be determined for any site in Oklahoma.

Storm-generated coral fragments - A viable source of transplants for reef rehabilitation

USGS Publications Warehouse

Garrison, V.; Ward, G.

2008-01-01

Coral reefs throughout the world have been damaged by storms, diseases, coral predators, temperature anomalies, and human activities. During the past three decades, recovery has been limited and patchy. Although a damaged coral reef cannot be restored to its original condition, interest in reef restoration is increasing. In a pilot project in the Caribbean (US Virgin Islands), storm-produced fragments of Acropora palmata, A. cervicornis, and Porites porites were collected from donor reefs and transplanted to nearby degraded reefs. Sixty coral fragments were attached to dead-coral substrate (usually A. palmata skeletons), at similar depths from which they had been collected (1-3.5 m), using nylon cable ties. Seventy-five intact colonies were designated as controls. Study colonies were assessed at 6-month intervals for 2 years (1999-2001) and annually thereafter (through 2004). One-fourth of the 135 colonies and fragments monitored were alive at the conclusion of the 5-year study. Survival of control and transplanted A. cervicornis and P. porites was very low (median survival 2.4 and 1.8 years, respectively), with no significant differences between transplant and control colonies. Site and depth did not contribute significantly to A. palmata colony survival, but colony size and transplant/control status did. Probability of survival increased with colony size. Median survival for A. palmata was 1.3 years for transplant and 4.3 years for natural colonies when not controlled for size. A. palmata was the only viable candidate for reef rehabilitation. Storm swells were the primary cause of mortality.

The impact of Pacific Decadal Oscillation on springtime dust activity in Syria

NASA Astrophysics Data System (ADS)

Pu, B.; Ginoux, P. A.

2016-12-01

The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific decadal oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003-2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabian to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa. On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria associated with increased precipitation in Turkey and northern Syria is also critical for the development of strong springtime dust storms in Syria.

The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

NASA Astrophysics Data System (ADS)

Pu, Bing; Ginoux, Paul

2016-10-01

The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria) is also critical for the development of strong springtime dust storms in Syria.

Watershed-based sources of polycyclic aromatic hydrocarbons in urban storm water.

PubMed

Stein, Eric D; Tiefenthaler, Liesl L; Schiff, Kenneth

2006-02-01

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds, ubiquitous in the air and water of urban environments, and have been shown to accumulate in coastal estuarine and marine sediments. Although previous studies have documented concentrations and loads of PAHs in urban runoff, little is known about the sources and temporal patterns of PAH loading from storm water. This study characterized the sources and temporal patterns of PAHs in urban storm water by analyzing PAH concentrations and loads from a range of homogeneous land use sites and in-river mass emission sites throughout the greater Los Angeles, California, USA, region. Samples were collected at 30- to 60-min intervals over the course of a storm during multiple storm events over a four-year period in order to investigate PAH sources and inter- and intrastorm patterns in loading. Polycyclic aromatic hydrocarbon storm fluxes ranged from 1.3 g/km2 for the largely undeveloped Arroyo Sequit watershed to 223.7 g/km2 for the highly urbanized Verdugo Wash watershed, with average storm fluxes being 46 times higher in developed versus undeveloped watersheds. Early-season storms repeatedly produced substantially higher loads than comparably sized late-season storms. Within individual storms, PAHs exhibited a moderate first flush with between 30 and 60% of the total PAH load being discharged in the first 20% of the storm volume. The relative distribution of individual PAHs demonstrated a consistent predominance of high-molecular-weight compounds indicative of pyrogenic sources.

Superstorm Sandy-related Morphologic and Sedimentologic Changes in an Estuarine System: Barnegat Bay-Little Egg Harbor Estuary, New Jersey

NASA Astrophysics Data System (ADS)

Miselis, J. L.; Ganju, N. K.; Navoy, A.; Nicholson, R.; Andrews, B.

2013-12-01

Despite the well-recognized ecological importance of back-barrier estuaries, the role of storms in their geomorphic evolution is poorly understood. Moreover, the focus of storm impact assessments is often the ocean shorelines of barrier islands rather than the exchange of sediment from barrier to estuary. In order to better understand and ultimately predict short-term morphologic and sedimentologic changes in coastal systems, a comprehensive research approach is required but is often difficult to achieve given the diversity of data required. An opportunity to use such an approach in assessing the storm-response of a barrier-estuary system occurred when Superstorm Sandy made landfall near Atlantic City, New Jersey on 29 October 2012. Since 2011, the US Geological Survey has been investigating water circulation and water-quality degradation in Barnegat Bay-Little Egg Harbor (BBLEH) Estuary, the southern end of which is approximately 25 kilometers north of the landfall location. This effort includes shallow-water geophysical surveys to map the bathymetry and sediment distribution within BBLEH, airborne topo-bathymetric lidar surveys for mapping the shallow shoals that border the estuary, and sediment sampling, all of which have provided a recent picture of the pre-storm estuarine geomorphology. We combined these pre-storm data with similar post-storm data from the estuary and pre- and post-storm topographic data from the ocean shoreline of the barrier island to begin to understand the response of the barrier-estuary system. Breaches in the barrier island resulted in water exchange between the estuary and the ocean, briefly reducing residence times in the northern part of the estuary until the breaches were closed. Few morphologic changes in water depths greater than 1.5 m were noted. However, morphologic changes observed in shallower depths along the eastern shoreline of the estuary are likely related to overwash processes. In general, surficial estuarine sediments were coarser post-Sandy, but, especially where observed along the western shoreline, it is unclear if the change is related to deposition of new sediment or winnowing of fine sediment. Further analysis will provide insight into whether the geometry of the barrier island and estuary influenced the morphologic and sedimentologic system response in BBLEH.

Sources of suspended sediment in the Waikele watershed, Oʻahu, Hawaiʻi

USGS Publications Warehouse

Izuka, Scot K.

2012-01-01

Data from streamflow/sediment gages and measurements of changes in channel-bed sediment storage were gathered between October 1, 2007, and September 30, 2010, to assess the sources of suspended sediment in the Waikele watershed, Oʻahu, Hawaiʻi. Streamflow from the watershed averaged 33 cubic feet per second during the study period, with interannual variations corresponding with variations in the frequency and magnitude of storm-flow peaks. Average streamflow during the study period was lower than the long-term average, but the study period included a storm on December 11, 2008, that caused record-high streamflows in parts of the watershed. Suspended-sediment yield from the Waikele watershed during the study period averaged 82,500 tons per year, which is 2.7 times higher than the long-term average. More than 90 percent of the yield during the study period was discharged during the December 11, 2008, storm. The study-period results are consistent with long-term records that show that the vast majority of suspended-sediment transport occurs during a few large storms. Results of this study also show that all but a small percentage of the suspended-sediment yield came from hillslopes. Only a small fraction of bed sediments is fine enough to be transported as suspended load; most bed sediments in the watershed are coarse. Silt and clay constitute less than 3 percent of the bed-sediment volume on average. Some larger clasts, however, can disintegrate during transport and contribute to the suspended load downstream. During the study period, suspended-sediment yield from the urbanized Mililani subbasin averaged 25 tons per year per square mile (tons/yr/mi2), which was much smaller than the yield from any other subbasin; these results indicate that urban land use yields much less sediment than other land uses. The wet, forested Kipapa subbasin had an average normalized hillslope suspended-sediment yield of 386 tons/yr/mi2; the average yield for forested areas in the watershed may be lower. Suspended-sediment yield from agricultural land use in the watershed is estimated to range between 5,590 and 6,440 tons/yr/mi2 during the study period; the long-term average is estimated to be 2,070 to 2,390 tons/yr/mi2. Of the three land uses considered, agriculture had by far the highest normalized suspended-sediment yield during this study - about an order of magnitude higher than forests and two orders of magnitude higher than urban areas.

Effects of variable regolith depth, hydraulic properties, and rainfall on debris-flow initiation during the September 2013 northern Colorado Front Range rainstorm

NASA Astrophysics Data System (ADS)

Baum, R. L.; Coe, J. A.; Kean, J. W.; Jones, E. S.; Godt, J.

2015-12-01

Heavy rainfall during 9 - 13 September 2013 induced about 1100 debris flows in the foothills and mountains of the northern Colorado Front Range. Weathered bedrock was partially exposed in the basal surfaces of many of the shallow source areas at depths ranging from 0.2 to 5 m. Typical values of saturated hydraulic conductivity of soils and regolith units mapped in the source areas range from about 10-4 - 10-6 m/s, with a median value of 2.8 x 10-5 m/s based on number of source areas in each map unit. Rainfall intensities varied spatially and temporally, from 0 to 2.5 x 10-5 m/s (90 mm/hour), with two periods of relatively heavy rainfall on September 12 - 13. The distribution of debris flows appears to correlate with total storm rainfall, and reported times of greatest landslide activity coincide with times of heaviest rainfall. Process-based models of rainfall infiltration and slope stability (TRIGRS) representing the observed ranges of regolith depth, hydraulic conductivity, and rainfall intensity, provide additional insights about the timing and distribution of debris flows from this storm. For example, small debris flows from shallower source areas (<2 m) occurred late on September 11 and in the early morning of September 12, whereas large debris flows from deeper (3 - 5 m) source areas in the western part of the affected area occurred late on September 12. Timing of these flows can be understood in terms of the time required for pore pressure rise depending on regolith depth and rainfall intensity. The variable hydraulic properties combined with variable regolith depth and slope angles account for much of the observed range in timing in areas of similar rainfall intensity and duration. Modeling indicates that the greatest and most rapid pore pressure rise likely occurred in areas of highest rainfall intensity and amount. This is consistent with the largest numbers of debris flows occurring on steep canyon walls in areas of high total storm rainfall.

Tropical warm pool rainfall variability and impact on upper ocean variability throughout the Madden-Julian oscillation

NASA Astrophysics Data System (ADS)

Thompson, Elizabeth J.

Heating and rain freshening often stabilize the upper tropical ocean, bringing the ocean mixed layer depth to the sea surface. Thin mixed layer depths concentrate subsequent fluxes of heat, momentum, and freshwater in a thin layer. Rapid heating and cooling of the tropical sea surface is important for controlling or triggering atmospheric convection. Ocean mixed layer depth and SST variability due to rainfall events have not been as comprehensively explored as the ocean's response to heating or momentum fluxes, but are very important to understand in the tropical warm pool where precipitation exceeds evaporation and many climate phenomena such as ENSO and the MJO (Madden Julian Oscillation) originate. The first part of the dissertation investigates tropical, oceanic convective and stratiform rainfall variability and determines how to most accurately estimate rainfall accumulation with radar from each rain type. The second, main part of the dissertation uses central Indian Ocean salinity and temperature microstructure measurements and surrounding radar-derived rainfall maps throughout two DYNAMO MJO events to determine the impact of precipitating systems on upper-ocean mixed layer depth and resulting SST variability. The ocean mixed layer was as shallow as 0-5 m during 528/1071 observation hours throughout 2 MJOs (54% of the data record). Out of 43 observation days, thirty-eight near-surface mixed layer depth events were attributed to freshwater stabilization, called rain-formed mixed layers (RFLs). Thirty other mixed layer stratification events were classified as diurnal warm layers (DWLs) due to stable temperature stratification by daytime heating. RFLs and DWLs were observed to interact in two ways: 1) RFLs fill preexisting DWLs and add to total near-surface mixed layer stratification, which occurred ten times; 2) RFLs last long enough to heat, creating a new DWL on top of the RFL, which happened nine times. These combination stratification events were responsible for the highest SST warming rates and some of the highest SSTs leading up to the most active precipitation and wind stage of the each MJO. DWLs without RFL interaction helped produce the highest SSTs in suppressed MJO conditions. As storm intensity, frequency, duration, and the ability of storms to maintain stratiform rain areas increased, RFLS became more common in the disturbed and active MJO phases. Along with the barrier layer, DWL and RFL stratification events helped suppress wind-mixing, cooling, and mixed layer deepening throughout the MJO. We hypothesize that both salinity and temperature stratification events, and their interactions, are important for controlling SST variability and therefore MJO initiation in the Indian Ocean. Most RFLs were caused by submesoscale and mesoscale convective systems with stratiform rain components and local rain accumulations above 10 mm but with winds mostly below 8 m s-1. We hypothesize that the stratiform rain components of storms helped stratify the ocean by providing weak but widespread, steady, long-lived freshwater fluxes. Although generally limited to rain rates ≤ 10 mm hr-1, it is demonstrated that stratiform rain can exert a strong buoyancy flux into the ocean, i.e. as high as maximum daytime solar heating. Storm morphology and the preexisting vertical structure of ocean stability were critical in determining ocean mixed layer depth variability in the presence of rain. Therefore, we suggest that high spatial and temporal resolution coupled ocean-atmosphere models that can parameterize or resolve storm morphology as well as ocean mixed layer and barrier layer evolution are needed to reproduce the diurnal and intraseasonal SST variability documented throughout the MJO.

The impact of Hurricane Sandy on the shoreface and inner shelf of Fire Island, New York: large bedform migration but limited erosion

USGS Publications Warehouse

Goff, John A.; Flood, Roger D.; Austin, James A.; Schwab, William C.; Christensen, Beth A.; Browne, Cassandra M.; Denny, Jane F.; Baldwin, Wayne E.

2015-01-01

We investigate the impact of superstorm Sandy on the lower shoreface and inner shelf offshore the barrier island system of Fire Island, NY using before-and-after surveys involving swath bathymetry, backscatter and CHIRP acoustic reflection data. As sea level rises over the long term, the shoreface and inner shelf are eroded as barrier islands migrate landward; large storms like Sandy are thought to be a primary driver of this largely evolutionary process. The “before” data were collected in 2011 by the U.S. Geological Survey as part of a long-term investigation of the Fire Island barrier system. The “after” data were collected in January, 2013, ~two months after the storm. Surprisingly, no widespread erosional event was observed. Rather, the primary impact of Sandy on the shoreface and inner shelf was to force migration of major bedforms (sand ridges and sorted bedforms) 10’s of meters WSW alongshore, decreasing in migration distance with increasing water depth. Although greater in rate, this migratory behavior is no different than observations made over the 15-year span prior to the 2011 survey. Stratigraphic observations of buried, offshore-thinning fluvial channels indicate that long-term erosion of older sediments is focused in water depths ranging from the base of the shoreface (~13–16 m) to ~21 m on the inner shelf, which is coincident with the range of depth over which sand ridges and sorted bedforms migrated in response to Sandy. We hypothesize that bedform migration regulates erosion over these water depths and controls the formation of a widely observed transgressive ravinement; focusing erosion of older material occurs at the base of the stoss (upcurrent) flank of the bedforms. Secondary storm impacts include the formation of ephemeral hummocky bedforms and the deposition of a mud event layer.

A Review of Spatial and Seasonal Changes in Condensation Clouds Observed During Aerobraking by MGS TES

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Smith, M. D.; Conrath, B. J.; Bandfield, J. L.; Christensen, P. R.

1999-01-01

Successful operation of the Mars Global Surveyor spacecraft beginning in September 1997, has permitted extensive infrared observations of condensation clouds during the martian southern summer and fall seasons (184 deg

Glider monitoring of shelf suspended particle dynamics and transport during storm and flooding conditions

NASA Astrophysics Data System (ADS)

Bourrin, François; Many, Gaël; Durrieu de Madron, Xavier; Martín, Jacobo; Puig, Pere; Houpert, Loic; Testor, Pierre; Kunesch, Stéphane; Mahiouz, Karim; Béguery, Laurent

2015-10-01

Transfers of particulate matter on continental margins primarily occur during energetic events. As part of the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) experiment, a glider equipped with optical sensors was deployed in the coastal area of the Gulf of Lions, NW Mediterranean in March 2011 to assess the spatio-temporal variability of hydrology, suspended particles properties and fluxes during energetic conditions. This deployment complemented a larger observational effort, a part of the MOOSE (Mediterranean Ocean Observing System of the Environment) network, composed of a coastal benthic station, a surface buoy and moorings on the continental slope. This set of observations permitted to measure the impact of three consecutive storms and a flood event across the entire continental shelf. Glider data showed that the sediment resuspension and transport observed at the coastal station during the largest storm (Hs>4 m) was effective down to a water depth of 80 m. The mid-shelf mud belt, located between 40 and 90 m depth, appears as the zone where the along-shelf flux of suspended sediment is maximum. Besides, the across-shelf flux of suspended sediment converges towards the outer limit of the mid-shelf mud belt, where deposition of suspended particles probably occurs and contributes to the nourishment of this area. Hydrological structures, suspended particles transport and properties changed drastically during stormy periods and the following flood event. Prior to the storms, the shelf waters were weakly stratified due in particular to the presence of cold dense water on the inner- and mid-shelf. The storms rapidly swept away this dense water, as well as the resuspended sediments, along the shelf and towards a downstream submarine canyon. The buoyant river plumes that spread along the shelf after the flooding period provoked a restratification of the water column on the inner- and mid-shelf. The analysis of glider's optical data at different wavelengths suggests that the coastal area and the bottom nepheloid layer during the largest storm are primarily composed of coarse particles, probably macroflocs, and that the size of particles decreases further offshore. A similar trend, albeit less contrasted, is observed after the flooding. This work provided a unique synoptic view across the entire shelf of the impact of a typical Mediterranean storm on bottom sediment erosion and particulate fluxes. Repeated glider transects across the south-western part of the Gulf of Lions shelf permitted for the first time to measure continuously the thermo-haline structures, the suspended particles concentrations and size, the current speed, and to estimate the particulate transport before, during and after typical Mediterranean storm events. Glider data complement and compare well with concomitant high frequency time series at fixed stations along the coast and in a downstream submarine canyon.

Jet and storm track variability and change: adiabatic QG zonal averages and beyond... (Invited)

NASA Astrophysics Data System (ADS)

Robinson, W. A.

2013-12-01

The zonally averaged structures of extratropical jets and stormtracks, their slow variations, and their responses to climate change are all tightly constrained on the one hand by thermal wind balance and the necessary application of eddy torques to produce zonally averaged meridional motion, and, on the other hand, by the necessity that eddies propagate upshear to extract energy from the mean flow. Combining these constraints with the well developed theory of linear Rossby-wave propagation on zonally symmetric basic states has led to a large and growing number of plausible mechanisms to explain observed and modeled jet/storm track variability and responses to climate change and idealized forcing. Hidden within zonal averages is the reality that most baroclinic eddy activity is destroyed at the same latitude at which is generated: from one end to another of the fixed stormtracks in the Northern Hemisphere and baroclinic wave packets in the Southern Hemisphere. Ignored within adiabatic QG theory is the reality that baroclinic eddies gain significant energy from latent heating that involves sub-syntopic scale structures and dynamics. Here we use results from high-resolution regional and global simulations of the Northern Hemisphere storm tracks to explore the importance of non-zonal and diabatic dynamics in influencing jet change and variability and their influences on the much-studied zonal means.

Climate, not conflict, explains extreme Middle East dust storm

DOE PAGES

Parolari, Anthony J.; Li, Dan; Bou-Zeid, Elie; ...

2016-11-08

The recent dust storm in the Middle East (Sepember 2015) was publicized in the media as a sign of an impending 'Dust Bowl.' Its severity, demonstrated by extreme aerosol optical depth in the atmosphere in the 99th percentile compared to historical data, was attributed to the ongoing regional conflict. However, surface meteorological and remote sensing data, as well as regional climate model simulations, support an alternative hypothesis: the historically unprecedented aridity played a more prominent role, as evidenced by unusual climatic and meteorological conditions prior to and during the storm. Remotely sensed normalized difference vegetation index demonstrates that vegetation covermore » was high in 2015 relative to the prior drought and conflict periods, suggesting that agricultural activity was not diminished during that year, thus negating the media narrative. Instead, meteorological simulations using the Weather Research and Forecasting (WRF) model show that the storm was associated with a cyclone and 'Shamal' winds, typical for dust storm generation in this region, that were immediately followed by an unusual wind reversal at low levels that spread dust west to the Mediterranean Coast. These unusual meteorological conditions were aided by a significant reduction in the critical shear stress due to extreme dry and hot conditions, thereby enhancing dust availability for erosion during this storm. Concluding, unusual aridity, combined with unique synoptic weather patterns, enhanced dust emission and westward long-range transport across the region, thus generating the extreme storm.« less

Climate, not conflict, explains extreme Middle East dust storm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parolari, Anthony J.; Li, Dan; Bou-Zeid, Elie

The recent dust storm in the Middle East (Sepember 2015) was publicized in the media as a sign of an impending 'Dust Bowl.' Its severity, demonstrated by extreme aerosol optical depth in the atmosphere in the 99th percentile compared to historical data, was attributed to the ongoing regional conflict. However, surface meteorological and remote sensing data, as well as regional climate model simulations, support an alternative hypothesis: the historically unprecedented aridity played a more prominent role, as evidenced by unusual climatic and meteorological conditions prior to and during the storm. Remotely sensed normalized difference vegetation index demonstrates that vegetation covermore » was high in 2015 relative to the prior drought and conflict periods, suggesting that agricultural activity was not diminished during that year, thus negating the media narrative. Instead, meteorological simulations using the Weather Research and Forecasting (WRF) model show that the storm was associated with a cyclone and 'Shamal' winds, typical for dust storm generation in this region, that were immediately followed by an unusual wind reversal at low levels that spread dust west to the Mediterranean Coast. These unusual meteorological conditions were aided by a significant reduction in the critical shear stress due to extreme dry and hot conditions, thereby enhancing dust availability for erosion during this storm. Concluding, unusual aridity, combined with unique synoptic weather patterns, enhanced dust emission and westward long-range transport across the region, thus generating the extreme storm.« less

Cyclone trends constrain monsoon variability during Late Oligocene sea level highstands (Kachchh Basin, NW India)

NASA Astrophysics Data System (ADS)

Reuter, M.; Piller, W. E.; Harzhauser, M.; Kroh, A.

2013-01-01

Important concerns about the consequences of climate change for India are the potential impact on tropical cyclones and the monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as an indicator of tropical cyclone activity along the NW Indian coast during the Late Oligocene warming period (~27-24 Ma). Direct proxies providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system in the Early Miocene. The vast shell concentrations comprise a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deep to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished each recording a relative storm wave base depth. (1) A shallow storm wave base is shown by nearshore mollusks, corals and Clypeaster echinoids; (2) an intermediate storm wave base depth is indicated by lepidocyclind foraminifers, Eupatagus echinoids and corallinaceans; and (3) a deep storm wave base is represented by an Amussiopecten-Schizaster echinoid assemblage. Vertical changes in these skeletal associations give evidence of gradually increasing tropical cyclone intensity in line with third-order sea level rise. The intensity of cyclones over the Arabian Sea is primarily linked to the strength of the Indian monsoon. Therefore and since the topographic boundary conditions for the Indian monsoon already existed in the Late Oligocene, the longer-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~26 Ma followed by a period of monsoon weakening during the peak of the Late Oligocene global warming (~24 Ma).

Flood of May 26-27, 1984 in Tulsa, Oklahoma

USGS Publications Warehouse

Bergman, DeRoy L.; Tortorelli, Robert L.

1988-01-01

The greatest flood disaster in the history of Tulsa, Oklahoma occurred during 8 hours from 2030 hours May 26 to 0430 hours May 27, 1984, as a result of intense rainfall centered over the metropolitan area. Storms of the magnitude that caused this flood are not uncommon to the southern great plains. Such storms are seldom documented in large urban areas. Total rainfall depth and rainfall distribution in the Tulsa metropolitan area during the May 26-27 storm were recorded by 16 recording rain gages. This report presents location of recording rain gages with corresponding rainfall histograms and mass curves, lines of equal rainfall depth (map A), and flood magnitudes and inundated areas of selected streams within the city (map B). The limits of the study areas (fig. 1) are the corporate boundaries of Tulsa, an area of about 185 square miles. Streams draining the city are: Dirty Butter, Coal, and Mingo Creeks which drain northward into Bird Creek along the northern boundary of the city; and Cherry, Crow, Harlow, Joe Haikey, Fry, Vensel, Fred, and Mooser Creeks which flow into the Arkansas River along the southern part of the city. Flooding along Haikey, Fry, Fred, Vensel, and Mooser Creeks was not documented for this report. The Arkansas River is regulated by Keystone Dam upstream from Tulsa (fig. 1). The Arkansas River remained below flood stage during the storm. Flooded areas in Tulsa (map B) were delineated on the topographic maps using flood profiles based on surveys of high-water marks identified immediately after the flood. The flood boundaries show the limits of stream flooding. Additional areas flooded because of overfilled storm drains or by sheet runoff are not shown in this report. Data presented in this report, including rainfall duration and frequency, and flood discharges and elevations, provide city officials and consultants a technical basis for making flood-plain management decisions.

Quantification of non-stormwater flow entries into storm drains using a water balance approach.

PubMed

Xu, Zuxin; Yin, Hailong; Li, Huaizheng

2014-07-15

To make decisions about correcting illicit or inappropriate connections to storm drains, quantification of non-stormwater entries into storm drains was performed using a water flow balance approach, based on data analysis from 2008 to 2011 in a separate storm drainage system in a Shanghai downtown area of 374 ha. The study revealed severe sewage connections to storm drains; meanwhile, misconnections between surface water and storm drains were found to drive frequent non-stormwater pumping discharges at the outfall, producing a much larger volume of outfall flows in a short period. This paper presented a methodology to estimate quantities of inappropriate sewage flow, groundwater infiltration and river water backflow into the storm drains. It was concluded that inappropriate sewage discharge and groundwater seepage into storm drains were approximately 17,860 m(3)/d (i.e., up to 51% of the total sewage flow in the catchment) and 3,624 m(3)/d, respectively, and surface water backflow was up to an average 28,593 m(3)/d. On the basis of this work, end-of-storm pipe interceptor sewers of 0.25 m(3)/s (i.e., 21,600 m(3)/d) would be effective to tackle the problem of sewage connections and groundwater seepage to storm drains. Under this circumstance, the follow-up non-stormwater outfall pumping events indicate misconnections between surface water and storm drains, featuring pumping discharge equivalent to surface water backflow; hence the misconnections should be repaired. The information provided here is helpful in estimating the magnitude of non-stormwater flow entries into storm drains and designing the necessary pollution control activities, as well as combating city floods in storm events. Copyright © 2014. Published by Elsevier B.V.

Treatment performance of a constructed wetland during storm and non-storm events in Korea.

PubMed

Maniquiz, M C; Lee, S Y; Choi, J Y; Jeong, S M; Kim, L H

2012-01-01

The efficiency of a free water surface flow constructed wetland (CW) in treating agricultural discharges from stream was investigated during storm and non-storm events between April and December, 2009. Physico-chemical and water quality constituents were monitored at five sampling locations along the flow path of the CW. The greatest reduction in pollutant concentration was observed after passing the sedimentation zone at approximately 4% fractional distance from the inflow. The inflow hydraulic loading, flow rates and pollutant concentrations were significantly higher and variable during storm events than non-storm (baseflow) condition (p <0.001) that resulted to an increase in the average pollutant removal efficiencies by 10 to 35%. The highest removal percentages were attained for phosphate (51 ± 22%), ammonium (44 ± 21%) and phosphorus (38 ± 19%) while nitrate was least effectively retained by the system with only 25 ± 17% removal during non-storm events. The efficiency of the system was most favorable when the temperature was above 15 °C (i.e., almost year-round except the winter months) and during storm events. Overall, the outflow water quality was better than the inflow water quality signifying the potential of the constructed wetland as a treatment system and capability of improving the stream water quality.

Electrical storms and their prognostic implications.

PubMed

Awan, Zahid Aslam; ul Hassan, Mahmood; Bangash, Kamran; Shah, Bakhtawar; Noor, Lubna

2009-01-01

Prevention of sudden cardiac death has always been a challenge for electrophysiologists and to date, automatic implantable cardiovertor defibrillator (AICD) is found to be the only remedy. This device delivers an intracardiac shock whenever it senses a fatal ventricular arrhythmia in order to achieve sinus rhythm. If the delivery of these intracardiac shocks becomes frequent, the situation is declared as an electrical storm. This article deals with the frequency, precipitating factors and prevention of electrical storms. One hundred and ten episodes of electrical storms (a total of 668 shocks) were retrospectively analysed in 25 recipients of automatic implantable cardioverter defibrillators. ECG, echocardiography, serum electrolytes, urea and creatinine were done for all the patients, and they were hospitalized for a minimum of 24 hours. During the 3 year study period, all the 25 patients with an implantable cardiovertor defibrillator, on an average, received one shock per two years. However, 12 out of these 25 patients (50%) had more than two shocks within 24 hours. Most of these patients with electrical storms were having active ischemia, electrolytes imbalances or renal failure. Electrical storms are common in patients with coronary artery disease with impaired left ventricular functions. Ischemia, electrolytes imbalances and renal failure predispose to the electrical storms. Electrical Storms are predictors of poor prognosis.

Revisiting the synoptic-scale predictability of severe European winter storms using ECMWF ensemble reforecasts

NASA Astrophysics Data System (ADS)

Pantillon, Florian; Knippertz, Peter; Corsmeier, Ulrich

2017-10-01

New insights into the synoptic-scale predictability of 25 severe European winter storms of the 1995-2015 period are obtained using the homogeneous ensemble reforecast dataset from the European Centre for Medium-Range Weather Forecasts. The predictability of the storms is assessed with different metrics including (a) the track and intensity to investigate the storms' dynamics and (b) the Storm Severity Index to estimate the impact of the associated wind gusts. The storms are well predicted by the whole ensemble up to 2-4 days ahead. At longer lead times, the number of members predicting the observed storms decreases and the ensemble average is not clearly defined for the track and intensity. The Extreme Forecast Index and Shift of Tails are therefore computed from the deviation of the ensemble from the model climate. Based on these indices, the model has some skill in forecasting the area covered by extreme wind gusts up to 10 days, which indicates a clear potential for early warnings. However, large variability is found between the individual storms. The poor predictability of outliers appears related to their physical characteristics such as explosive intensification or small size. Longer datasets with more cases would be needed to further substantiate these points.

Increase in dust storm related PM10 concentrations: A time series analysis of 2001-2015.

PubMed

Krasnov, Helena; Katra, Itzhak; Friger, Michael

2016-06-01

Over the last decades, changes in dust storms characteristics have been observed in different parts of the world. The changing frequency of dust storms in the southeastern Mediterranean has led to growing concern regarding atmospheric PM10 levels. A classic time series additive model was used in order to describe and evaluate the changes in PM10 concentrations during dust storm days in different cities in Israel, which is located at the margins of the global dust belt. The analysis revealed variations in the number of dust events and PM10 concentrations during 2001-2015. A significant increase in PM10 concentrations was identified since 2009 in the arid city of Beer Sheva, southern Israel. Average PM10 concentrations during dust days before 2009 were 406, 312, and 364 μg m(-3) (median 337, 269,302) for Beer Sheva, Rehovot (central Israel) and Modi'in (eastern Israel), respectively. After 2009 the average concentrations in these cities during dust storms were 536, 466, and 428 μg m(-3) (median 382, 335, 338), respectively. Regression analysis revealed associations between PM10 variations and seasonality, wind speed, as well as relative humidity. The trends and periodicity are stronger in the southern part of Israel, where higher PM10 concentrations are found. Since 2009 dust events became more extreme with much higher daily and hourly levels. The findings demonstrate that in the arid area variations of dust storms can be quantified easier through PM10 levels over a relatively short time scale of several years. Copyright © 2015 Elsevier Ltd. All rights reserved.

Polar cap potential saturation during the Bastille Day storm event using global MHD simulation

NASA Astrophysics Data System (ADS)

Kubota, Y.; Nagatsuma, T.; Den, M.; Tanaka, T.; Fujita, S.

2017-04-01

We investigated the temporal variations and saturation of the cross polar cap potential (CPCP) in the Bastille Day storm event (15 July 2000) by global magnetohydrodynamics (MHD) simulation. The CPCP is considered to depend on the electric field and dynamic pressure of the solar wind as well as on the ionospheric conductivity. Previous studies considered only the ionospheric conductivity due to solar extreme ultraviolet (EUV) variations. In this paper, we dealt with the changes in the CPCP attributable to auroral conductivity variations caused by pressure enhancement in the inner magnetosphere owing to energy injection from the magnetosphere because the energy injection is considerably enhanced in a severe magnetic storm event. Our simulation reveals that the auroral conductivity enhancement is significant for the CPCP variation in a severe magnetic storm event. The numerical results concerning the Bastille Day event show that the ionospheric conductivity averaged over the auroral oval is enhanced up to 18 mho in the case of Bz of less than -59 nT. On the other hand, the average conductivity without the auroral effect is almost 6 mho throughout the entire period. Resultantly, the saturated CPCP is about 240 kV in the former and 704 kV in the latter when Bz is -59 nT. This result indicates that the CPCP variations could be correctly reproduced when the time variation of auroral conductivity caused by pressure enhancement due to the energy injection from the magnetosphere is correctly considered in a severe magnetic storm event.

Modeling Tropical Cyclone Storm Surge and Wind Induced Risk Along the Bay of Bengal Coastline Using a Statistical Copula

NASA Astrophysics Data System (ADS)

Bushra, N.; Trepanier, J. C.; Rohli, R. V.

2017-12-01

High winds, torrential rain, and storm surges from tropical cyclones (TCs) cause massive destruction to property and cost the lives of many people. The coastline of the Bay of Bengal (BoB) ranks as one of the most susceptible to TC storm surges in the world due to low-lying elevation and a high frequency of occurrence. Bangladesh suffers the most due to its geographical setting and population density. Various models have been developed to predict storm surge in this region but none of them quantify statistical risk with empirical data. This study describes the relationship and dependency between empirical TC storm surge and peak reported wind speed at the BoB using a bivariate statistical copula and data from 1885-2011. An Archimedean, Gumbel copula with margins defined by the empirical distributions is specified as the most appropriate choice for the BoB. The model provides return periods for pairs of TC storm surge and peak wind along the BoB coastline. The BoB can expect a TC with peak reported winds of at least 24 m s-1 and surge heights of at least 4.0 m, on average, once every 3.2 years, with a quartile pointwise confidence interval of 2.7-3.8 years. In addition, the BoB can expect peak reported winds of 62 m s-1 and surge heights of at least 8.0 m, on average, once every 115.4 years, with a quartile pointwise confidence interval of 55.8-381.1 years. The purpose of the analysis is to increase the understanding of these dangerous TC characteristics to reduce fatalities and monetary losses into the future. Application of the copula will mitigate future threats of storm surge impacts on coastal communities of the BoB.

Response of the Mississippi Bight and Sound to the Passage of Tropical Storm Cindy Through the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Hode, L. E.; Howden, S. D.; Diercks, A. R.; Cambazoglu, M. K.; Jones, E. B.; Martin, K. M.

2017-12-01

Damage inflicted by tropical storms and hurricanes on coastal communities and industries has become a growing concern in recent decades. Consequently, utilizing products from existing ocean observing platforms, ocean modeling forecasts and satellite data helps to identify the effects of individual storms on the northern Gulf of Mexico. Using data from the jointly-operated United States Geological Survey and Mississippi Department of Marine Resources (USGS-MDMR) hydrological stations, National Oceanic and Atmospheric Administration (NOAA) tide gages, and the Central Gulf of Mexico Ocean Observing System (CenGOOS) high frequency radar (HFR) network, we tracked temperature, salinity, water level and surface current changes in the Mississippi Sound and Bight during June 2017. We performed time series analyses and compared conditions during the buildup and passage of tropical storm Cindy to climatological values as well as to satellite observations and results from a regional application of the Navy Coastal Ocean Model (NCOM). Elevated salinities proceeded Cindy's landfall on June 22, 2017, while anomalously fresh water marked all Mississippi Sound stations afterwards. Onshore surface currents dominated the Mississippi Bight, and current speeds exceeded more than four times the climatological average in the southeastern Bight. Indeed, regions of enhanced current speeds were observed throughout the month of June 2017. Tidal ranges in the Mississippi Sound were on average half a meter higher than predicted, and Shell Beach (Louisiana) and the Bay Waveland Yacht Club (Mississippi) saw extended periods where tides exceeded one meter above predicted values. These results help to quantify the tidal inundation caused by Cindy but also illustrate the massive riverine discharge driven by the storm's precipitation. Model results provide information on areas of the study region not covered by measurements; additionally, comparing observations to model products helps estimate model effectiveness for storm events. Though Cindy never became a hurricane, the storm caused extensive and widespread coastal flooding, strong surface currents and salinity fluctuations in the northern Gulf of Mexico.

Evolution of mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane: Implications for barrier-estuary connectivity

USGS Publications Warehouse

Miselis, Jennifer L.; Andrews, Brian D.; Nicholson, Robert S.; Defne, Zafer; Ganju, Neil K.; Navoy, Anthony S.

2016-01-01

Assessments of coupled barrier island-estuary storm response are rare. Hurricane Sandy made landfall during an investigation in Barnegat Bay-Little Egg Harbor estuary that included water quality monitoring, geomorphologic characterization, and numerical modeling; this provided an opportunity to characterize the storm response of the barrier island-estuary system. Barrier island morphologic response was characterized by significant changes in shoreline position, dune elevation, and beach volume; morphologic changes within the estuary were less dramatic with a net gain of only 200,000 m3 of sediment. When observed, estuarine deposition was adjacent to the back-barrier shoreline or collocated with maximum estuary depths. Estuarine sedimentologic changes correlated well with bed shear stresses derived from numerically simulated storm conditions, suggesting that change is linked to winnowing from elevated storm-related wave-current interactions rather than deposition. Rapid storm-related changes in estuarine water level, turbidity, and salinity were coincident with minima in island and estuarine widths, which may have influenced the location of two barrier island breaches. Barrier-estuary connectivity, or the transport of sediment from barrier island to estuary, was influenced by barrier island land use and width. Coupled assessments like this one provide critical information about storm-related coastal and estuarine sediment transport that may not be evident from investigations that consider only one component of the coastal system.

Beach cusp destruction, formation, and evolution during and subsequent to an extratropical storm, Duck, North Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, J.R.; Miller, S.M.O.; Torzynski, C.A.

Many studies have debated whether beach cusps are erosional or depositional features. The April 12-14, 1988, extratropical storm provided an opportunity to view the direct effects of one of the largest storms of the past decade upon beach sedimentology and morphology on barrier islands near Duck, North Carolina. Prior to the storm, the beach at Duck was characterized by a well-defined pattern of beach cusps with horn-to-horn spacings averaging 35 m. Storm-induced alterations were dominated by an initial period of beach erosion that remobilized the upper 30 to 50 cm of beach sediment, followed by aggradation. Net aggradation was mostmore » prominent along the middle beachface and within the pre-storm cusp bays. These morphologic adjustments resulted in the destruction of cusps, which were replaced with a post-storm planar beachface composed of horizontally bedded fine- to coarse-grained sediments. Within 24 hrs of storm subsidence, new beach cusps formed sequentially along the coast in the direction of longshore transport. Initial cusp formation resulted from beach erosion and the creation of bays in the planar storm-beach surface at positions of preferential post-storm runup. The initial cusp horns were composed of truncated horizontal beds of the planar beach accreted during the storm. After their formation, the cusps sequentially migrated downdrift. Migrating horns were composed of a coarse-grained sediment wedge that thickened toward horn crests, suggesting formation by deposition. It is concluded from these observations that beach cusps are both erosional and depositional in nature.« less

Carbon Monoxide Photoproduction from Particles and Solutes in the Delaware Estuary under Contrasting Hydrological Conditions.

PubMed

Song, Guisheng; Richardson, John D; Werner, James P; Xie, Huixiang; Kieber, David J

2015-12-15

Full-spectrum, ultraviolet (UV), and visible broadband apparent quantum yields (AQYs) for carbon monoxide (CO) photoproduction from chromophoric dissolved organic matter (CDOM) and particulate organic matter (POM) were determined in the Delaware Estuary in two hydrologically contrasting seasons in 2012: an unusually low flow in August and a storm-driven high flow in November. Average AQYs for CDOM and POM in November were 10 and 16 times the corresponding AQYs in August. Maximum AQYs in November occurred in a midestuary particle absorption maximum zone. Although POM AQYs were generally smaller than CDOM AQYs, the ratio of the former to the latter increased substantially from the UV to the visible. In both seasons, UV solar radiation was the primary driver for CO photoproduction from CDOM whereas visible light was the principal contributor to POM-based CO photoproduction. CDOM dominated CO photoproduction in the uppermost water layer while POM prevailed at deeper depths. On a depth-integrated basis, the Delaware Estuary shifted from a CDOM-dominated system in August to a POM-dominated system in November with respect to CO photoproduction. This study reveals that flood events may enhance photochemical cycling of terrigenous organic matter and switch the primary photochemical driver from CDOM to POM.

A thorough analysis of a severe dust storm in the Arabian Peninsula using WRF-CHEM, satellite imagery, and ground observations

NASA Astrophysics Data System (ADS)

Karagulian, F.; Ghebreyesus, D. T.; Weston, M.; Krishnan, V.; Temimi, M.; Al Hammadi, F.; Al Abdooli, A.

2017-12-01

A strong dust event occurred over the Arabian Peninsula from 1 to 3 April 2015. The event impacted the United Arab Emirates (UAE) on 2 April 2015 in the form of a dust storm. The origin and synopsis of the event is investigated in this study together with its impact on Air Quality in the UAE. The Weather Research Forecasting model coupled with chemistry (WRF-Chem) was run for the dates of the dust event. Outputs of the model were assessed against ground measurements of Particulate Matter (PM10) from monitoring stations in the United Arab Emirates (UAE), meteorological data, and the Aerosol Optical Depth from the new 1 km Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm for MODIS Terra and Aqua at 0.55 mm. Data from the geo-stationary satellite MSG SEVIRI was used to track the extent and the trajectory of the dust event across the Arabian Peninsula. This was supported by HYSPLIT back trajectory analysis simulated on hourly basis. The modeled results favorably agreed with ground observations of meteorological parameters at several monitoring stations in the UAE. On 2 and 3 April 2015, measurements and WRF-Chem simulations over the UAE showed northwest wind blowing within the range of 11-14 m s-1. Average surface temperature decreased from 33 to 26 ºC and the average radiance dropped by 50% during the peak time of the dust event with consequent reduction of the observed visibility down to 200 m in some UAE's cities. At local level, comparisons between modeled and estimated PM10 concentrations from monitoring stations and satellite data were somewhat biased by the saturated values recorded during the peak time of the dust event on 2 April 2015 with modeled lower limit average PM10 concentrations of 432 mg/m3 that were 25% lower than the ones from monitoring stations. On regional scale, the WRF-Chem model was able to estimate an upper limit values of PM10 concentrations during the dust event.

Biological response to coastal upwelling and dust deposition in the area off Northwest Africa

NASA Astrophysics Data System (ADS)

Ohde, T.; Siegel, H.

2010-05-01

Nutrient supply in the area off Northwest Africa is mainly regulated by two processes, coastal upwelling and deposition of Saharan dust. In the present study, both processes were analyzed and evaluated by different methods, including cross-correlation, multiple correlation, and event statistics, using remotely sensed proxies of the period from 2000 to 2008 to investigate their influence on the marine environment. The remotely sensed chlorophyll- a concentration was used as a proxy for the phytoplankton biomass stimulated by nutrient supply into the euphotic zone from deeper water layers and from the atmosphere. Satellite-derived alongshore wind stress and sea-surface temperature were applied as proxies for the strength and reflection of coastal upwelling processes. The westward wind and the dust component of the aerosol optical depth describe the transport direction of atmospheric dust and the atmospheric dust column load. Alongshore wind stress and induced upwelling processes were most significantly responsible for the surface chlorophyll- a variability, accounting for about 24% of the total variance, mainly in the winter and spring due to the strong north-easterly trade winds. The remotely sensed proxies allowed determination of time lags between biological response and its forcing processes. A delay of up to 16 days in the surface chlorophyll- a concentration due to the alongshore wind stress was determined in the northern winter and spring. Although input of atmospheric iron by dust storms can stimulate new phytoplankton production in the study area, only 5% of the surface chlorophyll- a variability could be ascribed to the dust component in the aerosol optical depth. All strong desert storms were identified by an event statistics in the time period from 2000 to 2008. The 57 strong storms were studied in relation to their biological response. Six events were clearly detected in which an increase of chlorophyll- a was caused by Saharan dust input and not by coastal upwelling processes. Time lags of <8 days, 8 days, and 16 days were determined. An increase in surface chlorophyll- a concentration of up to 2.4 mg m -3 after dust storms in which the dust component of the aerosol optical depth was up to 0.9 was observed.

A Process-Based Insight into the Severity of 'Super' Storm Desmond

NASA Astrophysics Data System (ADS)

Matthews, Tom; Murphy, Conor; Gerard, McCarthy; Rob, Wilby

2017-04-01

Climate warming is projected to increase winter rainfall and societally-impactful flood frequency across the British-Irish Isles (BI). The dynamical explanation for this change is linked to the North Atlantic (NA) storm track, with projections indicating both an enhanced frequency of wintertime extratropical cyclones ('cyclones'), and an increase in their average precipitation. The latter is, in part, a result of more intense moisture transport in cyclones' warm sectors by 'Atmospheric Rivers' (ARs), thermodynamically-driven by enhanced absolute humidity consistent with the Clausius-Clapeyron relation. It is against this backdrop that we scrutinise the physical drivers of the record-breaking rain and flood event associated with 'Storm Desmond' in December, 2015. We find that more than 3,500 km2 experienced rainfall in excess of the mean annual maximum during the storm's passage. The exceptional rain amounts were due to an AR more intense than any other in our observational record (1979-2015). However, we find that its unparalleled strength was as much a consequence of strong wind speeds as high humidity, so its severity cannot be attributed so simply to climate warming. This position is made clearer through a Lagrangian air mass tracking procedure, where we show that most (67%) of the moisture that precipitated out over BI during Desmond's passage evaporated from sea surfaces that were cooler than their 1951-1980 average. We therefore conclude that 1) the process-based observational approach applied here can provide valuable insight into climate change attribution assessments; and 2) Storm Desmond - despite being the most severe on record - was perhaps moderated by the anomalously cool NA sea-surface temperatures, which may have suppressed evaporation and vapour transport. The capacity for an even more impactful AR should SSTs in the sub-polar NA return to even their 20th Century averages, given otherwise identical synoptic circulation, should therefore be appreciated by planners and policy makers alike.

Mobile Launch Platform (MLP) Environmental Assessment

DTIC Science & Technology

2004-06-28

Sometimes these winds are interrupted by cool seasonal storms with southerly winds; dry offshore storms with southeasterly winds, called Santa Ana...winds; coastal eddies during the warm season with southeasterly winds over the inner waters; and alternating land and sea breezes that occur closer to...mean temperature of 14 oC (58 oF). Total annual precipitation averages 21.3 centimeters (8.4 inches). The dry season ranges from May to September and

Chemical and biological quality of Lakes Faith, Hope, and Charity at Maitland, Florida, with emphasis on the effects of storm runoff and bulk precipitation, 1971-1974

USGS Publications Warehouse

Gaggiani, Neville G.; Lamonds, A.G.

1978-01-01

Located in a closed basin, near Orlands, Fla., Lake Faith, Hope, and Charity cover a combined area of 132 acres and are surrounded by residential, citrus grove and undeveloped areas. All of these areas affect the water quality of the lakes through storm runoff and transport of windborne material. During a study from April 1971 to June 1974, stages of Lakes Faith, Hope, and Charity declined 1.5, 1.4, and 3.0 ft, respectively, because the rainfall was 3.78 in. below average for the area. Inflow to the lakes during this 3-year period was approximately 1,966 acre-ft of which 84 percent was by rainfall and 16 percent was by storm runoff. Rainfall and runoff brought in 82 tons of dissolved solids of which storm runoff carried 51 tons and bulk precipitation carried 32 tons. Dissolved solids concentrations in the lakes were relatively low, averaging 91, 132, and 212 mg/liter for Lakes Faith, Hope, and Charity, respecetively. Major ions, trace elements and nutrients were present in the lakes in relatively low concentrations. Phytoplankton and coliform population showed sharp seasonal fluctuations with the maximum population generally occurring during the warmer months. Blue-green algae predominated in all three lakes. (Woodard-USGS)

An analytic solution of the stochastic storage problem applicable to soil water

USGS Publications Warehouse

Milly, P.C.D.

1993-01-01

The accumulation of soil water during rainfall events and the subsequent depletion of soil water by evaporation between storms can be described, to first order, by simple accounting models. When the alternating supplies (precipitation) and demands (potential evaporation) are viewed as random variables, it follows that soil-water storage, evaporation, and runoff are also random variables. If the forcing (supply and demand) processes are stationary for a sufficiently long period of time, an asymptotic regime should eventually be reached where the probability distribution functions of storage, evaporation, and runoff are stationary and uniquely determined by the distribution functions of the forcing. Under the assumptions that the potential evaporation rate is constant, storm arrivals are Poisson-distributed, rainfall is instantaneous, and storm depth follows an exponential distribution, it is possible to derive the asymptotic distributions of storage, evaporation, and runoff analytically for a simple balance model. A particular result is that the fraction of rainfall converted to runoff is given by (1 - R−1)/(eα(1−R−1) − R−1), in which R is the ratio of mean potential evaporation to mean rainfall and a is the ratio of soil water-holding capacity to mean storm depth. The problem considered here is analogous to the well-known problem of storage in a reservoir behind a dam, for which the present work offers a new solution for reservoirs of finite capacity. A simple application of the results of this analysis suggests that random, intraseasonal fluctuations of precipitation cannot by themselves explain the observed dependence of the annual water balance on annual totals of precipitation and potential evaporation.

Diagnostic evaluation of the Community Earth System Model in simulating mineral dust emission with insight into large-scale dust storm mobilization in the Middle East and North Africa (MENA)

NASA Astrophysics Data System (ADS)

Parajuli, Sagar Prasad; Yang, Zong-Liang; Lawrence, David M.

2016-06-01

Large amounts of mineral dust are injected into the atmosphere during dust storms, which are common in the Middle East and North Africa (MENA) where most of the global dust hotspots are located. In this work, we present simulations of dust emission using the Community Earth System Model Version 1.2.2 (CESM 1.2.2) and evaluate how well it captures the spatio-temporal characteristics of dust emission in the MENA region with a focus on large-scale dust storm mobilization. We explicitly focus our analysis on the model's two major input parameters that affect the vertical mass flux of dust-surface winds and the soil erodibility factor. We analyze dust emissions in simulations with both prognostic CESM winds and with CESM winds that are nudged towards ERA-Interim reanalysis values. Simulations with three existing erodibility maps and a new observation-based erodibility map are also conducted. We compare the simulated results with MODIS satellite data, MACC reanalysis data, AERONET station data, and CALIPSO 3-d aerosol profile data. The dust emission simulated by CESM, when driven by nudged reanalysis winds, compares reasonably well with observations on daily to monthly time scales despite CESM being a global General Circulation Model. However, considerable bias exists around known high dust source locations in northwest/northeast Africa and over the Arabian Peninsula where recurring large-scale dust storms are common. The new observation-based erodibility map, which can represent anthropogenic dust sources that are not directly represented by existing erodibility maps, shows improved performance in terms of the simulated dust optical depth (DOD) and aerosol optical depth (AOD) compared to existing erodibility maps although the performance of different erodibility maps varies by region.

The relationships of seabird assemblages to physical habitat features in Pacific equatorial waters during spring 1984-1991

USGS Publications Warehouse

Ribic, C.A.; Ainley, D.G.

1997-01-01

The association of seabird species groups with physical habitat was investigated in the eastern tropical Pacific Ocean, far from any breeding colonies. This avoided birds that commute between colony and feeding habitat, behaviour that confuses associations with specific water types and current systems. Seabirds were counted on duplicate tracks in the eastern tropical Pacific each spring from 1984-1991. On each cruise, seabird habitat was measured on the basis of six factors and focused on three species groups: (A) black-winged petrel and white-winged petrel, (B) Juan Fernandez petrel, wedge-tailed shearwater, and sooty tern, and (C) Leach's storm-petrel and wedge-rumped storm-petrel. Group A was associated with the South Equatorial Current, particularly in cooler waters (median of 26.4??C); both petrel species followed this assemblage association with current. Group B was associated with areas characterized by deep thermoclines (median of 60 m) and low salinities (median of 34.33). Within Group B, two of the three species' responses were consistent with the group pattern; Juan Fernandez petrel differed by occurring more often where thermocline slopes were steep (median of 9.8 deg C m-1). Group C was not associated with any physical habitat variable. This was due to species in the group being associated with different habitats: Leach's storm-petrel with the tropical and equatorial surface water masses and wedge-rumped storm-petrel with waters having shallower thermocline depths (median of 22 m). Overall, two of the three assemblages appeared to be associated with physical habitat during spring with consistency among the species in the group. An association with thermocline depth may indicate that productivity was an important predictor of assemblage presence.

Bivariate frequency analysis of rainfall intensity and duration for urban stormwater infrastructure design

NASA Astrophysics Data System (ADS)

Jun, Changhyun; Qin, Xiaosheng; Gan, Thian Yew; Tung, Yeou-Koung; De Michele, Carlo

2017-10-01

This study presents a storm-event based bivariate frequency analysis approach to determine design rainfalls in which, the number, intensity and duration of actual rainstorm events were considered. To derive more realistic design storms, the occurrence probability of an individual rainstorm event was determined from the joint distribution of storm intensity and duration through a copula model. Hourly rainfall data were used at three climate stations respectively located in Singapore, South Korea and Canada. It was found that the proposed approach could give a more realistic description of rainfall characteristics of rainstorm events and design rainfalls. As results, the design rainfall quantities from actual rainstorm events at the three studied sites are consistently lower than those obtained from the conventional rainfall depth-duration-frequency (DDF) method, especially for short-duration storms (such as 1-h). It results from occurrence probabilities of each rainstorm event and a different angle for rainfall frequency analysis, and could offer an alternative way of describing extreme rainfall properties and potentially help improve the hydrologic design of stormwater management facilities in urban areas.

Winter Storm Jupiter of January 2017: Meteorological Drivers, Synoptic Evolution, and Climate Change Considerations in Portland, Oregon

NASA Astrophysics Data System (ADS)

Dean, S.; Loikith, P. C.

2017-12-01

Although the Pacific Northwest has some of the highest wintertime precipitation in the United States, most urban areas receive little in the way of snow. While 37 inches of wintertime rain fall in Portland on average annually, the city only receives four inches of snow on average. Although wintertime extreme snowstorm events are rare in Portland, in the last century they have occurred about once every ten years. On January 10-12th, 2017, winter storm Jupiter brought 11 inches of snow to downtown Portland within a 12-hour period, making it the largest snowstorm for the city in twenty years. The city declared a state of emergency, over 30,000 citizens lost power, and thousands of businesses were forced to shut down. The anomalously cold air and high amounts of snowfall in a short amount of time made the storm different from others in recent years. This study aims to discover the meteorological drivers behind the January 2017 snowstorm in Portland, Oregon. We also aim to understand how this storm compared with other local storms in the past, and assess the likelihood of a similar event occurring in the future. To do this, reanalysis data were used to display the synoptic evolution of the January 2017 storm. We compared this storm with two other extreme snowfall events from December 2008 and January 1980, assessing meteorological similarities and differences between storms. Results show that the 2017 event was associated with a slow moving, strong low-pressure system accompanied by a 500 hPa trough. These large-scale features helped drive slow moving, locally heavy snow bands over the city of Portland. At the same time, an unusually strong Arctic high-pressure system moved into the interior Pacific Northwest allowing for strong cold air advection west through the Cascade Mountain Range and Columbia River Gorge. Temperature trends show warming of 1-2 °C in the Pacific Northwest since the middle of the last century. Because of this, uncertainty associated with occurrence and magnitude of extreme snowfall events with respect to climate change must also be assessed. Understanding essential questions about the synoptic evolution of extreme snowfall events will better equip meteorologists and city planners to understand how this event occurred, and what to look for to better prepare Pacific Northwest cities for future storms.

Holocene reworking of a sand sheet in the Merrimack Embayment, Western Gulf of Maine

USGS Publications Warehouse

Hein, C.J.; FitzGerald, D.M.; Barnhardt, W.

2007-01-01

Recent bathymetric, backscatter, and seafloor sediment samples demonstrate that a large sand sheet was formed in the inner shelf by the reworking of the Merrimack River lowstand delta (deposited 12 kya; currently at 45 m depth) and braid plain during the Holocene transgression. Asymmetric bedforms and distinct grain size distributions suggest the sand sheet is actively being reworked by inner-shelf processes. Bottom sediments range from silty sand at the submerged delta to coarse sand and fine gravel in the innermost shelf (depth: 10-50 m). Coarse-grained sand comprises an expansive (32 km2 ) featureless sand sheet centered off the Merrimack River. Fine-grained sand discontinuously overlies this sand sheet in many locations and forms long wavelength (100 – 800 m), low amplitude (1-2 m), asymmetrical bedforms. Sets of these bedforms are oriented from slightly oblique offshore to onshore; several bedform sets are located within 1 km and oriented orthogonally to one another. Along the paleo-delta front north-northwest oriented bedforms are dominant. Inshore of these features, the bedforms become more closely spaced and have orientations to the west and westsouthwest. Preliminary data suggest that the combined forcings of instantaneous storm-wave generated shear stress and storm-induced currents associated with high energy northeast storm events may be responsible for sand sheet reworking and bedform development.

Wave setup over a Pacific Island fringing reef

NASA Astrophysics Data System (ADS)

Vetter, O.; Becker, J. M.; Merrifield, M. A.; Pequignet, A.-C.; Aucan, J.; Boc, S. J.; Pollock, C. E.

2010-12-01

Measurements obtained across a shore-attached, fringing reef on the southeast coast of the island of Guam are examined to determine the relationship between incident waves and wave-driven setup during storm and nonstorm conditions. Wave setup on the reef flat correlates well (r > 0.95) and scales near the shore as approximately 35% of the incident root mean square wave height in 8 m water depth. Waves generated by tropical storm Man-Yi result in a 1.3 m setup during the peak of the storm. Predictions based on traditional setup theory (steady state, inviscid cross-shore momentum and depth-limited wave breaking) and an idealized model of localized wave breaking at the fore reef are in agreement with the observations. The reef flat setup is used to estimate a similarity parameter at breaking that is in agreement with observations from a steeply sloping sandy beach. A weak (˜10%) increase in setup is observed across the reef flat during wave events. The inclusion of bottom stress in the cross-shore momentum balance may account for a portion of this signal, but this assessment is inconclusive as the reef flat currents in some cases are in the wrong direction to account for the increase. An independent check of fringing reef setup dynamics is carried out for measurements at the neighboring island of Saipan with good agreement.

Research on electrical properties of severe thunderstorms in the Great Plains

NASA Technical Reports Server (NTRS)

Rust, W. D.; Taylor, W. L.; Macgorman, D. R.; Arnold, R. T.

1981-01-01

Techniques, equipment, and results of studies (1978-1980) to determine the relationships between electrical phenomena and the dynamics and precipitation of storms are reported. Doppler and conventional radar, video tapes and movies, and VHF recording devices were used to monitor an area 200 x 100 km, aligned SW to NE. The 23 cm radar and a Doppler radar were employed to acquire radar echoes from lightning. Observations of a squall line, a severe storm, and radar echoes from electrical discharges are described. Positively charged cloud-to-ground lightning was observed during the severe and final stages of severe storms; average lightning rates and total flashes for normal and severe storms are provided. Comparisons of lightning echoes and electric field changes indicated that abrupt increases in radar reflectivity were correlated with return strokes and K-type field changes.

Building regional early flood warning systems by AI techniques

NASA Astrophysics Data System (ADS)

Chang, F. J.; Chang, L. C.; Amin, M. Z. B. M.

2017-12-01

Building early flood warning system is essential for the protection of the residents against flood hazards and make actions to mitigate the losses. This study implements AI technology for forecasting multi-step-ahead regional flood inundation maps during storm events. The methodology includes three major schemes: (1) configuring the self-organizing map (SOM) to categorize a large number of regional inundation maps into a meaningful topology; (2) building dynamic neural networks to forecast multi-step-ahead average inundated depths (AID); and (3) adjusting the weights of the selected neuron in the constructed SOM based on the forecasted AID to obtain real-time regional inundation maps. The proposed models are trained, and tested based on a large number of inundation data sets collected in regions with the most frequent and serious flooding in the river basin. The results appear that the SOM topological relationships between individual neurons and their neighbouring neurons are visible and clearly distinguishable, and the hybrid model can continuously provide multistep-ahead visible regional inundation maps with high resolution during storm events, which have relatively small RMSE values and high R2 as compared with numerical simulation data sets. The computing time is only few seconds, and thereby leads to real-time regional flood inundation forecasting and make early flood inundation warning system. We demonstrate that the proposed hybrid ANN-based model has a robust and reliable predictive ability and can be used for early warning to mitigate flood disasters.

Formation of ionospheric irregularities over Southeast Asia during the 2015 St. Patrick's Day storm

NASA Astrophysics Data System (ADS)

Spogli, Luca; Cesaroni, Claudio; Di Mauro, Domenico; Pezzopane, Michael; Alfonsi, Lucilla; Musicò, Elvira; Povero, Gabriella; Pini, Marco; Dovis, Fabio; Romero, Rodrigo; Linty, Nicola; Abadi, Prayitno; Nuraeni, Fitri; Husin, Asnawi; Le Huy, Minh; Lan, Tran Thi; La, The Vinh; Pillat, Valdir Gil; Floury, Nicolas

2016-12-01

We investigate the geospace response to the 2015 St. Patrick's Day storm leveraging on instruments spread over Southeast Asia (SEA), covering a wide longitudinal sector of the low-latitude ionosphere. A regional characterization of the storm is provided, identifying the peculiarities of ionospheric irregularity formation. The novelties of this work are the characterization in a broad longitudinal range and the methodology relying on the integration of data acquired by Global Navigation Satellite System (GNSS) receivers, magnetometers, ionosondes, and Swarm satellites. This work is a legacy of the project EquatoRial Ionosphere Characterization in Asia (ERICA). ERICA aimed to capture the features of both crests of the equatorial ionospheric anomaly (EIA) and trough (EIT) by means of a dedicated measurement campaign. The campaign lasted from March to October 2015 and was able to observe the ionospheric variability causing effects on radio systems, GNSS in particular. The multiinstrumental and multiparametric observations of the region enabled an in-depth investigation of the response to the largest geomagnetic storm of the current solar cycle in a region scarcely reported in literature. Our work discusses the comparison between northern and southern crests of the EIA in the SEA region. The observations recorded positive and negative ionospheric storms, spread F conditions, scintillation enhancement and inhibition, and total electron content variability. The ancillary information on the local magnetic field highlights the variety of ionospheric perturbations during the different storm phases. The combined use of ionospheric bottomside, topside, and integrated information points out how the storm affects the F layer altitude and the consequent enhancement/suppression of scintillations.

Removal of H 2S via an iron catalytic cycle and iron sulfide precipitation in the water column of dead end tributaries

NASA Astrophysics Data System (ADS)

Ma, Shufen; Noble, Abigail; Butcher, Derek; Trouwborst, Robert E.; Luther, George W., III

2006-11-01

The oxidation and precipitation of H 2S were investigated in Torquay Canal and Bald Eagle Creek, two tributaries of northern Rehoboth Bay, one of the Delaware Inland Bays. These man-made dead end canals develop seasonal anoxia and have been the site of past fish kills and harmful algal blooms. The canals have multiple holes over 5.5 m deep compared to an average low tide depth of 2 m. In situ determination for dissolved O 2, H 2S and other Fe and S redox species were conducted with a solid-state Au/Hg microelectrode in 2003 and 2004. Laboratory analyses of discrete samples were also performed to measure dissolved and particulate Fe, Mn, and S 8 to follow the seasonal dynamics of O, S, Fe and Mn redox species. Our results indicate that the water in the holes becomes stratified with O 2 decreasing with depth and H 2S increasing with depth. Dissolved Fe was as high as 30 μM whereas dissolved Mn was only 0.2 μM in the water column, indicating that Fe is the dominant metal involved in S redox cycling and precipitation. In surface oxic waters, the dominant form of Fe was particulate Fe(III) (oxy)hydroxides. When seasonal anoxia developed, Fe(III) (oxy)hydroxides were reduced by H 2S to Fe(II) at the oxic-anoxic interface. The Fe(II) reduced from particulate Fe can be re-oxidized to Fe(III) by O 2 above and at the interface to form a catalytic cycle to oxidize H 2S. Elemental S is the predominant oxidation product and was as high as 30 μM level (as S 0) at the interface. When the system was stable, the Fe catalytic cycle prevented H 2S from being released into surface waters during seasonal anoxia. However, when storms came, the water column was overturned and H 2S was released to the surface water. The reaction rates for the Fe catalytic cycle are not fast enough and the concentration of Fe was not high enough to regulate the high concentration of H 2S in surface waters during storm and mixing events.

Ionospheric redistribution during geomagnetic storms

PubMed Central

Immel, T J; Mannucci, A J

2013-01-01

[1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

Ionospheric redistribution during geomagnetic storms.

PubMed

Immel, T J; Mannucci, A J

2013-12-01

[1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active ( D s t <-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

The Association between Dust Storms and Daily Non ...

EPA Pesticide Factsheets

Background:The impact of dust storms on human health has been studied in the context of Asian,Saharan, Arabian, and Australian storms,but there has been no recent population-level epidemiological research on the dust storms in North America . The relevance of dust storms to public health is likely to increase as extreme weather events are predicted to become more frequent with anticipated changes in climate through the 21st century.Objectives: We examined the association between dust storms and county-level non-accidental mortality in the United States from 1993 through 2005.Methods:Dust storm incidence data, including date and approximate location. are taken from the U.S. National Weather Service storm database. County-level mortality data for the years 1993-2005 were acquired from the National Center for Health Statistics. Distributed lag conditionallogistic regression models under a time-stratified case-crossover design were used to study the relationship between dust storms and daily mortality counts over the whole United States and in Arizona and California specifically. End points included total non-accidental mortality and three mortality subgroups (cardiovascular, respiratory, and other non-acc idental).Results: We estimated that for the United States as a whole, total non-accidental mortality increased by 7.4% (95% Cl: 1.6, 13.5; p = 0.011) and 6.7% (95% Cl: 1.1,12.6; p = 0.018) at 2- and 3-day lags, respectively, and by an average of 2.7% (95% Cl: 0.4,

Hydrography of the Gulf of Maine and Massachusetts Bay, data report for R/V OCEANUS cruise 181, 5-15 February 1987

USGS Publications Warehouse

Moody, John A.; Butman, Bradford; Shoukimas, Polly; Donoghue, Terence G.

1990-01-01

During Cruise 181, a total of 95 hydrographic profiles were obtained by means of a conductivity-temperature-depth (CTD) profiler. Stations are numbered sequentially and station information is tabulated in table 1. The stations were arranged in ten transects (figure 1). Section 1 was across the Great South Channel and section 7 was across the Northeast Channel--the two main oceanic entrances and exits of the Gulf of Maine. Section 2 was along a saddle (Rodgers Pass) separating Wilkinson Basin from Georges Basin. Sections 3,5, and 10 were across different regions of Wilkinson Basin and all intersected at the longterm mooring site W1 in the center of Wilkinson Basin; section 8 was a dog-leg section through the southern portion of Jordan Basin; and sections 6 (east-west) and 9 (north-south) were within Georges Basin. A severe winter storm (see table 2 and 3) occurred between February 9 and 10 and work was stopped while the OCEANUS rode out the storm in Cape Cod Bay and repaired storm damage. Section 4 across Massachusetts Bay and section 5 across Wilkinson Basin, were repeated twice, once before the storm (sections 4a and 5a) and once after the storm (sections 4b and 5b).

Testing Taylor’s hypothesis in Amazonian rainfall fields during the WETAMC/LBA experiment

NASA Astrophysics Data System (ADS)

Poveda, Germán; Zuluaga, Manuel D.

2005-11-01

Taylor's hypothesis (TH) for rainfall fields states that the spatial correlation of rainfall intensity at two points at the same instant of time can be equated with the temporal correlation at two instants of time at some fixed location. The validity of TH is tested in a set of 12 storms developed in Rondonia, southwestern Amazonia, Brazil, during the January-February 1999 Wet Season Atmospheric Meso-scale Campaign. The time Eulerian and Lagrangian Autocorrelation Functions (ACF) are estimated, as well as the time-averaged space ACF, using radar rainfall rates of storms spanning between 3.2 and 23 h, measured at 7-10-min time resolution, over a circle of 100 km radius, at 2 km spatial resolution. TH does not hold in 9 out of the 12 studied storms, due to their erratic trajectories and very low values of zonal wind velocity at 700 hPa, independently from underlying atmospheric stability conditions. TH was shown to hold for 3 storms, up to a cutoff time scale of 10-15 min, which is closely related to observed features of the life cycle of convective cells in the region. Such cutoff time scale in Amazonian storms is much shorter than the 40 min identified in mid-latitude convective storms, due to much higher values of CAPE and smaller values of storm speed in Amazonian storms as compared to mid-latitude ones, which in turn contribute to a faster destruction of the rainfall field isotropy. Storms satisfying TH undergo smooth linear trajectories over space, and exhibit the highest negative values of maximum, mean and minimum zonal wind velocity at 700 hPa, within narrow ranges of atmospheric stability conditions. Non-dimensional parameters involving CAPE (maximum, mean and minimum) and CINE (mean) are identified during the storms life cycle, for which TH holds: CAPE mean/CINE mean = [30-35], CAPE max/CINE mean = [32-40], and CAPE min/CINE mean = [22-28]. These findings are independent upon the timing of storms within the diurnal cycle. Also, the estimated Eulerian time ACF's decay faster than the time-averaged space and the Lagrangian time ACF's, irrespectively of TH validity. The Eulerian ACF's exhibit shorter e-folding times, reflecting smaller correlations over short time scales, but also shorter scale of fluctuation, reflecting less persistence in time than over space. No significant associations (linear, exponential or power law) were found between estimated e-folding times and scale of fluctuation, with all estimates of CAPE and CINE. Secondary correlation maxima appear between 50 and 70 min in the Lagrangian time ACF's for storms satisfying TH. No differences were found in the behavior of each of the three ACF's for storms developed during either the Easterly or Westerly zonal wind regimes which characterize the development of meso-scale convective systems over the region. These results have important implications for modelling and downscaling rainfall fields over tropical land areas.

Quantifications of Geomagnetic Storm Impact on TEC and NmF2 during 2013 Mar. event

NASA Astrophysics Data System (ADS)

Shim, J. S.; Tsagouri, I.; Goncharenko, L. P.; Mays, M. L.; Taktakishvili, A.; Rastaetter, L.; Kuznetsova, M. M.

2016-12-01

We investigate the ionospheric response to 2013 Mar. geomagnetic storm event using GPS TEC, ISR and ionosonde observations in North American sector. In order to quantify variations of TEC and NmF2 (or foF2) due to the storm, we remove the background quiet-time values (e.g., TEC of one day prior to the storm, NmF2 median and average of five quietest days for 30 days prior to the storm). In addition, in order to assess modeling capability of reproducing storm impacts on TEC and NmF2, we compare the observations with various model simulations, which are obtained from empirical, physics-based, and data assimilation models. Further, we investigate how uncertainty in the interplanetary magnetic field (IMF) impacts on TEC and NmF2 during the geomagnetic storm event. For this uncertainty study, we use a physics-based coupled ionosphere-thermosphere model, CTIPe, and solar wind parameters obtained from ensemble of WSA-ENLIL+Cone model simulations. This study has been supported by the Community Coordinated Modeling Center (CCMC) at the Goddard Space Flight Center. Model outputs and observational data used for the study will be permanently posted at the CCMC website (http://ccmc.gsfc.nasa.gov) for the space science communities to use.

Migrating Shoals on Ebb-tidal Deltas: Results from Numerical Simulations

NASA Astrophysics Data System (ADS)

van der Vegt, M.; Ridderinkhof, W.; De Swart, H. E.; Hoekstra, P.

2016-02-01

Many ebb-tidal deltas show repetitive patterns of channel- shoal generation, migration and attachment of shoals to the downdrift barrier coast. For the Wadden Sea coast along the Dutch, German en Danish coastline the typical time scale of shoal attachment ranges from several to hundred years. There is a weak correlation between the tidal prism and the typical time scale of shoal attachment. The main aim of this research is to clarify the physical processes that result in the formation of shoals on ebb-tidal deltas and to study what determines their propagation speed. To this end numerical simulations were performed in Delft3D. Starting from an idealized geometry with a sloping bed on the shelf sea and a flat bed in the back barrier basin, the model was spun up until an approximate morphodynamic steady state was realized. The model was forced with tides and constant wave forcing based on the yearly average conditions along the Dutch Wadden coast. The resulting ebb-tidal delta is called the equilibrium delta. Next, two types of scenarios were run. First, the equilibrium delta was breached by creating a channel and adding the removed sand volume to the downdrift shoal. Second, the wave climate was made more realistic by adding storms and subsequently its effect on the equilibrium delta was simulated. Based on the model results we conclude the following. First, the model is able to realistically simulate the migration of shoals and the attachment to the downdrift barrier island. Second, larger waves result in faster propagation of the shoals. Third, simulations suggest that shoals only migrate when they are shallower than a critical maximum depth with respect to the wave height. These shallow shoals can be `man-made' or be generated during storms. When no storms were added to the wave climate and the bed was not artificially disturbed, no migrating shoals were simulated. During the presentation the underlying physical processes will be discussed in detail.

Inner Surf/Swash Zone Morphodynamic Numerical Model Simulation of an Accreting Ridge during Low-Energy Wave Conditions

NASA Astrophysics Data System (ADS)

Song, Youn Kyung; Figlus, Jens; Chardón-Maldonado, Patricia; Puleo, Jack A.

2017-04-01

The inner surf/swash zone of a coastal beach is characterized as an intermittently wet and dry zone in the nearshore that often develops a variety of morphological features including intertidal bars and ridge-runnel (RR) systems. The cross-shore morphodynamic numerical model CSHORE is used to simulate the beach recovery observed during a field experiment carried out at South Bethany Beach, Delaware, a nourished, high-gradient meso-tidal sandy beach along the U. S. Coast. The field campaign was conducted from February 12 to February 25, 2014 to measure bed profile morphology change and sediment characteristics along with detailed hydrodynamic forcing parameters at six cross-shore stations, closely spaced over approximately 50 m in the inner surf and swash zone. On February 13, 2014 a Nor'easter eroded significant portions of the beach leading to formation of a pronounced RR system on the beach face that subsequently accreted in the recovery process after the storm. Bed profile changes, surf and swash velocity profiles, water free surface elevation and suspended sediment concentrations recorded during the recovery at the cross-shore measuring locations on the seaward face of the accreting ridge are compared with CSHORE simulation results. During post-storm recovery, CSHORE demonstrates shoreward migration of the ridge and slight accretion on the beach face by the end of the simulation period on February 25, 2014. This trend was also observed in the field, where accretion at the ridge crest was up to 1.0 m with respect to the post-storm profile. The CSHORE parameters critical to improving model performance in reproducing measured morphodynamics and hydrodynamics during the ridge accretion process are examined and calibrated. Initial results show promise in using this type of efficient, process-based model to reproduce morphological evolution and depth-averaged hydrodynamics as a result of the complex surf and swash zone dynamics associated with beach accretion and RR system mobilization.

Probabilistic storm surge inundation maps for Metro Manila based on Philippine public storm warning signals

NASA Astrophysics Data System (ADS)

Tablazon, J.; Caro, C. V.; Lagmay, A. M. F.; Briones, J. B. L.; Dasallas, L.; Lapidez, J. P.; Santiago, J.; Suarez, J. K.; Ladiero, C.; Gonzalo, L. A.; Mungcal, M. T. F.; Malano, V.

2015-03-01

A storm surge is the sudden rise of sea water over the astronomical tides, generated by an approaching storm. This event poses a major threat to the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013. This hydro-meteorological hazard is one of the main reasons for the high number of casualties due to the typhoon, with 6300 deaths. It became evident that the need to develop a storm surge inundation map is of utmost importance. To develop these maps, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH) simulated historical tropical cyclones that entered the Philippine Area of Responsibility. The Japan Meteorological Agency storm surge model was used to simulate storm surge heights. The frequency distribution of the maximum storm surge heights was calculated using simulation results of tropical cyclones under a specific public storm warning signal (PSWS) that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of inundation for a specific PSWS using the probability of exceedance derived from the frequency distribution. Buildings and other structures were assigned a probability of exceedance depending on their occupancy category, i.e., 1% probability of exceedance for critical facilities, 10% probability of exceedance for special occupancy structures, and 25% for standard occupancy and miscellaneous structures. The maps produced show the storm-surge-vulnerable areas in Metro Manila, illustrated by the flood depth of up to 4 m and extent of up to 6.5 km from the coastline. This information can help local government units in developing early warning systems, disaster preparedness and mitigation plans, vulnerability assessments, risk-sensitive land use plans, shoreline defense efforts, and coastal protection measures. These maps can also determine the best areas to build critical structures, or at least determine the level of protection of these structures should they be built in hazard areas. Moreover, these will support the local government units' mandate to raise public awareness, disseminate information about storm surge hazards, and implement appropriate countermeasures for a given PSWS.

Martian Dust Cycle

NASA Astrophysics Data System (ADS)

Cantor, B. A.; James, P. B.

The Mars Observer Camera (MOC), aboard Mars Global Surveyor (MGS), has completed approximately 3 consecutive Martian years of global monitoring, since entering its mapping orbit on March 9, 1999. MOC observations have shown the important role that dust devils and dust storms play in the Martian dust cycle on time scales ranging from semi-diurnally to interannually. These dust events have been observed across much of the planet from the depths of Hellas basin to the summit of Arsia Mons and range in size from10s of meters across (dust devils) to planet encircling (global dust veils). Though dust devils occur throughout most of the Martian year, each hemisphere has a "dust devil season" that generally follows the subsolar latitude and appears to be repeatable from year-to-year. An exception is NW Amazonis, which has frequent, large dust devils throughout northern spring and summer. MOC observations show no evidence that dust devils cause or lead to dust storms, however, observations do suggest that dust storms can initiate dust devil activity. Dust devils also might play a role in maintaining the low background dust opacity of the Martian atmosphere. Dust storms occur almost daily with few exceptions, with 1000s occurring each year in the present Martian environment, dispelling the notion of a "Classical Dust Storm Season". However, there does appear to be an annual dust storm cycle, with storms developing in specific locations during certain seasons and that some individual storm events are repeatable from year-to-year. The majority of storms develop near the receding seasonal polar cap edge or along the corresponding polar hood boundaries in their respective hemispheres, but they also occur in the northern plains, the windward side of the large shield volcanoes, and in low laying regions such as Hellas, Argyre, and Chryse. The rarest of dust events are the "Great Storms" or "Global Events", of which only 6 (4 "planet encircling" and 2 "global") have been observed to date. With MOC we have observed that global dust events are not individual storms but are composed of a number of local and regional storms (sources) and that they do not signify climatic changes, but are only short-term perturbations to the general interannually repeatable Martian dust storm cycle.

A review of tropical cyclone-generated storm surges: Global data sources, observations, and impacts

NASA Astrophysics Data System (ADS)

Needham, Hal F.; Keim, Barry D.; Sathiaraj, David

2015-06-01

Tropical cyclone-generated storm surges are among the world's most deadly and destructive natural hazards. This paper provides the first comprehensive global review of tropical storm surge data sources, observations, and impacts while archiving data in SURGEDAT, a global database. Available literature has provided data for more than 700 surge events since 1880, the majority of which are found in the western North Atlantic (WNA), followed by Australia/Oceania, the western North Pacific (WNP), and the northern Indian Ocean (NIO). The Bay of Bengal (BOB) in the NIO consistently observes the world's highest surges, as this subbasin averages five surges ≥5 m per decade and has observed credible storm tide levels reaching 13.7 m. The WNP observes the highest rate of low-magnitude surges, as the coast of China averages 54 surges ≥1 m per decade, and rates are likely higher in the Philippines. The U.S. Gulf Coast observes the second highest frequency of both high-magnitude (≥5 m) and low-magnitude (≥1 m) surges. The BOB observes the most catastrophic surge impacts, as 59% of global tropical cyclones that have killed at least 5000 people occurred in this basin. The six deadliest cyclones in this region have each killed at least 140,000 people, and two events have killed 300,000. Storm surge impacts transportation, agriculture, and energy sectors in the WNA. Oceania experiences long-term impacts, including contamination of fresh water and loss of food supplies, although the highest surges in this region are lower than most other basins.

Reconstruction of pre-instrumental storm track trajectories across the U.S. Pacific Northwest using circulation-based field sampling of Pinus Ponderosa

NASA Astrophysics Data System (ADS)

Wise, E.; Dannenberg, M. P.

2015-12-01

The trajectory of incoming storms from the Pacific Ocean is a key influence on drought and flood regimes in western North America. Flow is typically from the west in a zonal pattern, but decadal shifts between zonal and meridional flow have been identified as key features in hydroclimatic variability over the instrumental period. In Washington and most of the Pacific Northwest, there tend to be lower-latitude storm systems that result in decreased precipitation in El Niño years. However, the Columbia Basin in central Washington behaves in opposition to the surrounding region and typically has average to above-average precipitation in El Niño years due to changing storm-track trajectories and a decreasing rain shadow effect on the leeward side of the Cascades. This direct connection between storm-track position and precipitation patterns in Washington provided an exceptional opportunity for circulation-based field sampling and chronology development. New Pinus ponderosa (Ponderosa pine) tree-ring chronologies were developed from eight sites around the Columbia Basin in Washington and used to examine year-to-year changes in moisture regimes. Results show that these sites are representative of the two distinct climate response areas. The divergence points between these two site responses allowed us to reconstruct changing precipitation patterns since the late-17th century, and to link these patterns to previously reconstructed atmospheric pressure and El Niño indices. This study highlights the potential for using synoptic climatology to inform field-based proxy collection.

Floods in Kansas City, Missouri and Kansas, September 12-13, 1977

USGS Publications Warehouse

Hauth, Leland D.; Carswell, William J.

1978-01-01

The storm of September 12-13, 1977, produced as much as 16 inches of rainfall in the Kansas City, Missouri-Kansas area, left 25 persons dead, many homeless, and caused over 50 million dollars in damages.Data from National Weather Service recording rain gages indicate the storm came in two bursts within 24 hours. Flood hydrographs developed from streamflow records in the area also reflect the two events, with the second yielding the greater runoff.Peak discharges were determined during and after flood at gaging stations and selected miscellaneous locations. Peak discharges in areas of great rainfall depths were well over the criteria for the 100-year flood.

Three-Dimensional Simulations of Oblique Asteroid Impacts into Water

NASA Astrophysics Data System (ADS)

Gisler, G. R.; Ferguson, J. M.; Heberling, T.; Plesko, C. S.; Weaver, R.

2016-12-01

Waves generated by impacts into oceans may represent the most significant danger from near-earth asteroids and comets. For impacts near populated shores, the crown splash and subsequent waves, accompanied by sediment lofting and high winds, could be more damaging than storm surges from the strongest hurricanes. For asteroids less than 500 m in diameter that impact into deep water far from shores, the waves produced will be detectable over large distances, but probably not significantly dangerous. We present new three-dimensional simulations of oblique impacts into deep water, with trajectory angles ranging from 20 degrees to 60 degrees (where 90 degrees is vertical). These simulations are performed with the Los Alamos Rage hydrocode, and include atmospheric effects including ablation and airbursts. These oblique impact simulations are specifically performed in order to help determine whether there are additional dangers from the obliquity of impact not covered by previous two-dimensional studies. Water surface elevation profiles, surface pressures, and depth-averaged mass fluxes within the water are prepared for use in propagation studies.

A Review of Spatial and Seasonal Changes in Condensation Clouds Observed During Aerobraking by MGS TES

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Smith, M. D.; Conrath, B. J.; Bandfield, J. L.; Christensen, P. R.

1999-01-01

Successful operation of the Mars Global Surveyor spacecraft, beginning in September 1997, has permitted extensive infrared observations of condensation clouds during the martian southern summer and fall seasons (184 deg less than L(sub s) less than 28 deg). Initially, thin (normal optical depth less than 0.06 at 825/ cm) ice clouds and hazes were widespread, showing a latitudinal gradient. With the onset of a regional dust storm at L(sub s) = 224 deg, ice clouds essentially vanished in the southern hemisphere, to reappear gradually after the decay of the storm. The thickest clouds (optical depth approx. 0.6) were associated with major volcanic features. At L(exp s) = 318 deg, the cloud at Ascraeus Mons was observed to disappear between 21:30 and 09:30, consistent with historically recorded diurnal behavior for clouds of this type. Limb observations showed extended optically thin (depth less than 0.04) stratiform clouds at altitudes up to 55 km. A water ice haze was present in the north polar night at altitudes up to 40 km; this probably provided heterogeneous nucleation sites for the formation of CO2 clouds at altitudes below the 1 mbar pressure level, where atmospheric temperatures dropped to the condensation point of CO2.

The Effects of Lightning NO(x) Production during the July 21 EULINOX Storm studied with a 3-D Cloud-scale Chemical Transport Model

NASA Technical Reports Server (NTRS)

Ott, Lesley E.; Pickering, Kenneth E.; Stenchikov, Georgiy L.; Huntrieser, Heidi; Schumann, Ulrich

2006-01-01

The July 21,1998 thunderstonn observed during the European Lightning Nitrogen Oxides Project (EULINOX) project was simulated using the three-dimensional Goddard Cumulus Ensemble (GCE) model. The simulation successfully reproduced a number of observed storm features including the splitting of the original cell into a southern cell which developed supercell characteristics, and a northern cell which became multicellular. Output from the GCE simulation was used to drive an offline cloud-scale chemical transport model which calculates tracer transport and includes a parameterization of lightning NO(x) production which uses observed flash rates as input. Estimates of lightning NO(x) production were deduced by assuming various values of production per intracloud and production per cloud-to-ground flash and comparing the results with in-cloud aircraft observations. The assumption that both types of flashes produce 360 moles of NO per flash on average compared most favorably with column mass and probability distribution functions calculated from observations. This assumed production per flash corresponds to a global annual lightning NOx source of 7 Tg N per yr. Chemical reactions were included in the model to evaluate the impact of lightning NO(x), on ozone. During the storm, the inclusion of lightning NOx in the model results in a small loss of ozone (on average less than 4 ppbv) at all model levels. Simulations of the chemical environment in the 24 hours following the storm show on average a small increase in the net production of ozone at most levels resulting from lightning NO(x), maximizing at approximately 5 ppbv per day at 5.5 km. Between 8 and 10.5 km, lightning NO(x) causes decreased net ozone production.

Effects of lightning NOx production during the 21 July European Lightning Nitrogen Oxides Project storm studied with a three-dimensional cloud-scale chemical transport model

NASA Astrophysics Data System (ADS)

Ott, Lesley E.; Pickering, Kenneth E.; Stenchikov, Georgiy L.; Huntrieser, Heidi; Schumann, Ulrich

2007-03-01

The 21 July 1998 thunderstorm observed during the European Lightning Nitrogen Oxides Project (EULINOX) project was simulated using the three-dimensional Goddard Cumulus Ensemble (GCE) model. The simulation successfully reproduced a number of observed storm features including the splitting of the original cell into a southern cell which developed supercell characteristics and a northern cell which became multicellular. Output from the GCE simulation was used to drive an offline cloud-scale chemical transport model which calculates tracer transport and includes a parameterization of lightning NOx production which uses observed flash rates as input. Estimates of lightning NOx production were deduced by assuming various values of production per intracloud and production per cloud-to-ground flash and comparing the results with in-cloud aircraft observations. The assumption that both types of flashes produce 360 moles of NO per flash on average compared most favorably with column mass and probability distribution functions calculated from observations. This assumed production per flash corresponds to a global annual lightning NOx source of 7 Tg N yr-1. Chemical reactions were included in the model to evaluate the impact of lightning NOx on ozone. During the storm, the inclusion of lightning NOx in the model results in a small loss of ozone (on average less than 4 ppbv) at all model levels. Simulations of the chemical environment in the 24 hours following the storm show on average a small increase in the net production of ozone at most levels resulting from lightning NOx, maximizing at approximately 5 ppbv day-1 at 5.5 km. Between 8 and 10.5 km, lightning NOx causes decreased net ozone production.

The effect of sand storms on acute asthma in Riyadh, Saudi Arabia.

PubMed

Alangari, Abdullah A; Riaz, Muhammad; Mahjoub, Mohamed Osman; Malhis, Nidal; Al-Tamimi, Saleh; Al-Modaihsh, Abdullah

2015-01-01

Major sand storms are frequent in the Middle East. This study aims to investigate the role of air particulate matter (PM) level in acute asthma in children in Riyadh, Saudi Arabia. An aerosol spectrometer was used to evaluate PM < 10μm in diameter (PM10) and PM < 2.5 μm in diameter (PM2.5) concentrations in the air every 30 minutes throughout February and March 2012 in Riyadh. Data on children 2-12 years of age presenting to the emergency department of a major children's hospital with acute asthma during the same period were collected including their acute asthma severity score. The median with interquartile range (IQR) levels of PM10 and PM2.5 were 454 μg/m(3) (309,864) and 108 μg/m(3) (72,192) respectively. There was no correlation between the average daily PM10 levels and the average number of children presenting with acute asthma per day (r = -0.14, P = 0.45), their daily asthma score (r = 0.014, P = 0.94), or admission rate ( r= -0.08, P = 0.65). This was also true for average daily PM2.5 levels. In addition, there was no difference in these variables between days with PM10 >1000 μg/m(3), representing major sand storms, plus the following 5 days and other days with PM10< 1000 μg/m(3). Sand storms, even major ones, had no significant impact on acute asthma exacerbations in children in Riyadh, Saudi Arabia. The very high levels of PM, however, deserve further studying especially of their long-term effects.

Thermal Tides During the 2001 Martian Global-Scale Dust Storm

NASA Technical Reports Server (NTRS)

Guzewich, Scott D.; Wilson, R. John; McConnochie, Timothy H.; Toigo, Anthony D.; Bandfield, Donald J.; Smith, Michael D.

2014-01-01

The 2001 (Mars Year 25) global dust storm radically altered the dynamics of the Martian atmosphere. Using observations from the Thermal Emission Spectrometer onboard the Mars Global Surveyor spacecraft and Mars WRF general circulation model simulations, we examine the changes to thermal tides and planetary waves caused by the storm. We find that the extratropical diurnal migrating tide is dramatically enhanced during the storm, particularly in the southern hemisphere, reaching amplitudes of more than 20 K. The tropical diurnal migrating tide is weakened to almost undetectable levels. The diurnal Kelvin waves are also significantly weakened, particularly during the period of global expansion at Ls=200deg-210deg. In contrast, the westward propagating diurnal wavenumber 2 tide strengthens to 4-8 K at altitudes above 30km. The wavenumber 1 stationary wave reaches amplitudes of 10-12 K at 50deg-70degN, far larger than is typically seen during this time of year. The phase of this stationary wave and the enhancement of the diurnal wavenumber 2 tide appear to be responses to the high-altitude westward propagating equatorial wavenumber 1 structure in dust mixing ratio observed during the storm in previous works. This work provides a global picture of dust storm wave dynamics that reveals the coupling between the tropics and high-latitude wave responses. We conclude that the zonal distribution of thermotidal forcing from atmospheric aerosol concentration is as important to understanding the atmospheric wave response as the total global mean aerosol optical depth.

Climatology of dust distribution over West Asia from homogenized remote sensing data

NASA Astrophysics Data System (ADS)

Nabavi, Seyed Omid; Haimberger, Leopold; Samimi, Cyrus

2016-06-01

In the past decade, West Asia has witnessed more frequent and intensified dust storms affecting Iran and Persian Gulf countries. Employing a varying threshold that takes into account systematic differences between TOMS and OMI data, TOMS-OMI Aerosol Index data are used to identify long-term changes in the horizontal distribution of dust storms in West Asia from 1980 to present. The northwest of Iraq and east of Syria are identified as emerging dusty areas, whereas east of Saudi Arabia and southeast of Iraq are identified as permanent dusty areas, including both dust sources and affected areas. Whereas the frequency of dust events increased slightly in the permanent dusty areas, it increased markedly in the emerging dusty areas. As expected, the frequency of dust events is highest in June and July. The dust source areas are identified as the Iraq-Saudi Arabia boundary region and (recently) the northwest of Iraq, using MODIS deep blue aerosol optical depth data. Subsequently, a lagged correlation was implemented between identified dust sources and whole West Asia to determine the main paths and receptors of intense dust storms. Accordingly, southwest of Iran and Persian Gulf countries were determined as main receptors of summertime dust storms in West Asia. During spring, dust storms mostly hit the northern half of the region and reach to the Caspian Sea. Analyzing atmospheric patterns, Shamal and Frontal patterns were found as dominant atmospheric circulations simultaneous with summertime and springtime dust storms, respectively.

Characteristics of a group of Hubei Golden Snub-nosed Monkeys (Rhinopithecus roxellana hubeiensis) before and after major snow storms.

PubMed

Li, Yiming; Liu, Xuecong; Liao, Mingyao; Yang, Jingyuan; Stanford, Craig B

2009-06-01

Natural disasters can negatively affect primate population demography and social group structure. A clear understanding of these effects has important implications for wildlife conservation. The worst snow storms in nearly five decades hit portions of southern and central China between January 10 and February 6, 2008, presenting a unique opportunity to observe their immediate effects on a previously studied group of Hubei Golden Snub-nosed Monkeys (Rhinopithecus roxellana hubeiensis) in temperate forests in Shennongjia Nature Reserve, Hubei Province, China. We recorded social and demographic characteristics of the group before and after the snow storms. The average group size decreased from 270 individuals before the storms to 197 individuals after the storms, a reduction of 27.2%. Adult females (30.1%), juveniles (38.1%) and infants (55.4%) suffered higher mortality than did adult males (15.7%). Despite age and sex-based differences in mortality, the ratios of adult males to adult females, adults to immatures and adult females to immatures remained similar before and after the storms. However, higher mortality among females, juveniles and infants may reduce the group's long-term potential for growth.

Arctic moisture source for Eurasian snow cover variations in autumn

NASA Astrophysics Data System (ADS)

Wegmann, Martin; Orsolini, Yvan; Vázquez Dominguez, Marta; Gimeno Presa, Luis; Nieto, Raquel; Buligyna, Olga; Jaiser, Ralf; Handorf, Dörthe; Rinke, Anette; Dethloff, Klaus; Sterin, Alexander; Brönnimann, Stefan

2015-04-01

Global warming is enhanced at high northern latitudes where the Arctic surface air temperature has risen at twice the rate of the global average in recent decades - a feature called Arctic amplification. This recent Arctic warming signal likely results from several factors such as the albedo feedback due to a diminishing cryosphere, enhanced poleward atmospheric and oceanic transport, and change in humidity. The reduction in Arctic sea ice is without doubt substantial and a key factor. Arctic summer sea-ice extent has declined by more than 10% per decade since the start of the satellite era (e.g. Stroeve et al., 2012), culminating in a new record low in September 2012, with the long-term trend largely attributed to anthropogenic global warming. Eurasian snow cover changes have been suggested as a driver for changes in the Arctic Oscillation and might provide a link between sea ice decline in the Arctic during summer and atmospheric circulation in the following winter. However, the mechanism connecting snow cover in Eurasia to sea ice decline in autumn is still under debate. Our analysis focuses at sea ice decline in the Barents-Kara Sea region, which allows us to specify regions of interest for FLEXPART forward and backwards moisture trajectories. Based on Eularian and Lagrangian diagnostics from ERA-INTERIM, we can address the origin and cause of late autumn snow depth variations in a dense (snow observations from 820 land stations), unutilized observational datasets over the Commonwealth of Independent States. Open waters in the Barents and Kara Sea have been shown to increase the diabatic heating of the atmosphere, which amplifies baroclinic cyclones and might induce a remote atmospheric response by triggering stationary Rossby waves (Honda et al. 2009). In agreement with these studies, our results show enhanced storm activity originating at the Barents and Kara with disturbances entering the continent through a small sector from the Barents and Kara Seas, steered in October by a Scandinavia block and a low to the East, extending to Central Russia land areas. The disturbances transport moisture southward where their tracks merge with the eastward extension of the Mediterranean storm track. Maxima in storm activity trigger increasing uplift, often accompanied by positive snowfall and snow depth anomalies. We show that declining sea ice in the Barents and Kara Seas acts as moisture source for enhanced Siberian snow cover as a result of changed tropospheric moisture transport. Transient disturbances enter the continent from the Barents and Kara Seas region related to anomalies in the planetary wave pattern and move southward along the Ural mountains.

A method for determining average beach slope and beach slope variability for U.S. sandy coastlines

USGS Publications Warehouse

Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.

2015-01-01

The U.S. Geological Survey (USGS) National Assessment of Hurricane-Induced Coastal Erosion Hazards compares measurements of beach morphology with storm-induced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The wave-induced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storm-induced changes in beach slope can lead to differences on the order of 1 meter (m) in wave-induced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200-m alongshore section of coastline.

Analysis of satellite data on energetic particles of ionospheric origin

NASA Technical Reports Server (NTRS)

Sharp, R. D.; Johnson, R. G.; Shelley, E. G.

1975-01-01

The morphology was studied of precipitating O(+) and H(+) ions in the energy range 0.7 equal to or less than E equal to or less than 12 keV during the storm-time period from December 16-18, 1971, which encompassed two principal magnetic storms. The results are described with emphasis on the temporal variations of parameters characterizing the intensity, average energy, and spatial location of the zones of precipitation of the two ionic species. One of the principal results was the finding that the intensity of the precipitating O(+) ions was well correlated with the geomagnetic indices which measure the strength of magnetospheric substorm activity and the strength of the storm-time ring current. Since the O(+) ions are almost certainly of ionospheric origin the correlations indicate that a previously unknown strong coupling mechanism existed between the magnetosphere and the ionosphere during the storm period.

Toward Quantifying the Impact of Atmospheric Forcing on Arctic Sea Ice Variability Using the NPS 1/12 Degree Pan-Arctic Coupled Ice-Ocean Model

DTIC Science & Technology

2010-03-01

strong while the temperatures over Scandinavia and Europe (eastern Arctic) are warmer and winds are weaker than average (Serreze and Barry 2005...than the Fram Strait branch than previously thought. This could facilitate an increase in the frequency of storms reaching higher latitudes...REFERENCES Ackerman, J. T., 2008: Climate Change, National Security, and the Quadrennial Defense Review: Avoiding the Perfect Storm . Strategic Studies

Stream Channel Stability. Appendix A. Evaluation of Streambank Erosion Control Demonstration Projects in the Bluff Line Streams of Northwest Mississippi,

DTIC Science & Technology

1981-04-01

streambanks except on very small channels and agricultural waterways. Vegetation is commonly used to stabilize small agricultural storm runoff ...subjected to severe hydrologic and plant growth stresses during 1980. Large storm runoff events, occurring early in the year, produced velocities in...than average for the prevailing conditions. The overall survival rate for the 1979 and 1980 plantings of the shrub type bristly locus (Robinia fertilis

National Economic Development Procedures Manual. Coastal Storm Damage and Erosion

DTIC Science & Technology

1991-09-01

study area is temperate with warm summers and moderate winters. The annual temperature averages approximately 53 degrees Fahrenheit (*F). On average ...January is the coolest month with a mean temperature of 32°F and July is the warmest month. The average annual precipitation is about 45 inches with...0704.0188 Public rooing burden for rhr$ LoIlecton of ,nformaton .s estma eO to average I hour oer resiorse including the time for resrewing inttuctiOn

Geomagnetic storm effects on the occurrences of ionospheric irregularities over the African equatorial/low-latitude region

NASA Astrophysics Data System (ADS)

Amaechi, P. O.; Oyeyemi, E. O.; Akala, A. O.

2018-04-01

The study investigated the effects of intense geomagnetic storms of 2015 on the occurrences of large scale ionospheric irregularities over the African equatorial/low-latitude region. Four major/intense geomagnetic storms of 2015 were analyzed for this study. These storms occurred on 17th March 2015 (-229 nT), 22nd June 2015 (-204 nT), 7th October 2015 (-124 nT), and 20th December 2015 (-170 nT). Total Electron Content (TEC) data obtained from five African Global Navigation Satellite Systems (GNSS) stations, grouped into eastern and western sectors were used to derive the ionospheric irregularities proxy indices, e.g., rate of change of TEC (ROT), ROT index (ROTI) and ROTI daily average (ROTIAVE). These indices were characterized alongside with the disturbance storm time (Dst), the Y component of the Interplanetary Electric Field (IEFy), polar cap (PC) index and the H component of the Earth's magnetic field from ground-based magnetometers. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) and disturbance dynamo electric field (DDEF) modulated the behaviour of irregularities during the main and recovery phases of the geomagnetic storms. The effect of electric field over both sectors depends on the local time of southward turning of IMF Bz. Consequently, westward electric field inhibited irregularities during the main phase of March and October 2015 geomagnetic storms, while for the June 2015 storm, eastward electric field triggered weak irregularities over the eastern sector. The effect of electric field on irregularities during December 2015 storm was insignificant. During the recovery phase of the storms, westward DDEF suppressed irregularities.

Some characteristics of intense geomagnetic storms and their energy budget

NASA Astrophysics Data System (ADS)

Vichare, Geeta; Alex, S.; Lakhina, G. S.

2005-03-01

The present study analyses nine intense geomagnetic storms (∣Dst∣ > 175 nT) with the aid of ACE satellite measurements and ground magnetic field values at Alibag Magnetic Observatory. The study confirms the crucial role of southward IMF in triggering the storm main phase as well as controlling the magnitude of the storm. The main phase interval shows clear dependence on the duration of southward IMF. An attempt is made to identify the multipeak signature in the ring current energy injection rate during main phase of the storm. In order to quantify the energy budget of magnetic storms, the present paper computes the solar wind energies, magnetospheric coupling energies, auroral and Joule heating energies, and the ring current energies for each storm under examination. Computation of the solar wind- magnetosphere coupling function considers the variation of the size of the magnetosphere by using the measured solar wind ram pressure. During the main phase of the storm, the solar wind kinetic energy ranges from 9 × 1017 to 72 × 1017 J with an average of 30 × 1017 J; the total energy dissipated in the auroral ionosphere varies between 2 × 1015 and 9 × 1015 J, whereas ring current energies range from 8 × 1015 to 19 × 1015 J. For the total storm period, about 3.5% of total solar wind kinetic energy is available for the redistribution in the magnetosphere, and around 20% of this goes into the inner magnetosphere and in the auroral ionosphere of both the hemispheres. It is found that during main phase of the storm, almost 5% of the total solar wind kinetic energy is available for the redistribution in the magnetosphere, whereas during the recovery phase the percentage becomes 2.3%.

Statistical uncertainty of extreme wind storms over Europe derived from a probabilistic clustering technique

NASA Astrophysics Data System (ADS)

Walz, Michael; Leckebusch, Gregor C.

2016-04-01

Extratropical wind storms pose one of the most dangerous and loss intensive natural hazards for Europe. However, due to only 50 years of high quality observational data, it is difficult to assess the statistical uncertainty of these sparse events just based on observations. Over the last decade seasonal ensemble forecasts have become indispensable in quantifying the uncertainty of weather prediction on seasonal timescales. In this study seasonal forecasts are used in a climatological context: By making use of the up to 51 ensemble members, a broad and physically consistent statistical base can be created. This base can then be used to assess the statistical uncertainty of extreme wind storm occurrence more accurately. In order to determine the statistical uncertainty of storms with different paths of progression, a probabilistic clustering approach using regression mixture models is used to objectively assign storm tracks (either based on core pressure or on extreme wind speeds) to different clusters. The advantage of this technique is that the entire lifetime of a storm is considered for the clustering algorithm. Quadratic curves are found to describe the storm tracks most accurately. Three main clusters (diagonal, horizontal or vertical progression of the storm track) can be identified, each of which have their own particulate features. Basic storm features like average velocity and duration are calculated and compared for each cluster. The main benefit of this clustering technique, however, is to evaluate if the clusters show different degrees of uncertainty, e.g. more (less) spread for tracks approaching Europe horizontally (diagonally). This statistical uncertainty is compared for different seasonal forecast products.

Variability of dissolved organic carbon in precipitation during storms at the Shale Hills Critical Zone Observatory

USGS Publications Warehouse

Iavorivska , Lidiia; Boyer, Elizabeth W.; Grimm, Jeffrey W.; Miller, Matthew P.; DeWalle, David R.; Davis, Kenneth J.; Kaye, Margot W.

2017-01-01

Organic compounds are removed from the atmosphere and deposited to the earth's surface via precipitation. In this study, we quantified variations of dissolved organic carbon (DOC) in precipitation during storm events at the Shale Hills Critical Zone Observatory, a forested watershed in central Pennsylvania (USA). Precipitation samples were collected consecutively throughout the storm during 13 events, which spanned a range of seasons and synoptic meteorological conditions, including a hurricane. Further, we explored factors that affect the temporal variability by considering relationships of DOC in precipitation with atmospheric and storm characteristics. Concentrations and chemical composition of DOC changed considerably during storms, with the magnitude of change within individual events being comparable or higher than the range of variation in average event composition among events. While some previous studies observed that concentrations of other elements in precipitation typically decrease over the course of individual storm events, results of this study show that DOC concentrations in precipitation are highly variable. During most storm events concentrations decreased over time, possibly as a result of washing out of the below-cloud atmosphere. However, increasing concentrations that were observed in the later stages of some storm events highlight that DOC removal with precipitation is not merely a dilution response. Increases in DOC during events could result from advection of air masses, local emissions during breaks in precipitation, or chemical transformations in the atmosphere that enhance solubility of organic carbon compounds. This work advances understanding of processes occurring during storms that are relevant to studies of atmospheric chemistry, carbon cycling, and ecosystem responses.

Hurricane Ike Deposits on the Bolivar Peninsula, Galveston Bay, Texas

NASA Astrophysics Data System (ADS)

Evans, C. A.; Wilkinson, M. J.; Eppler, D.

2011-12-01

In September 2008, Hurricane Ike made landfall on Galveston Bay, close to the NASA Johnson Space Center (JSC). The storm flooded much of the area with a storm surge ranging from 11-20 feet. The Bolivar peninsula, the southeastern coast of Galveston Bay, experienced the brunt of the surge. Several agencies collected excellent imagery baselines before the storm and complementary data a few days afterward that helped define the impacts of the storm. In April of 2011, a team of scientists and astronauts from JSC conducted field mapping exercises along the Bolivar Peninsula, the section of the Galveston Bay coast most impacted by the storm. Astronauts routinely observe and document coastal changes from orbit aboard the International Space Station. As part of their basic Earth Science training, scientists at the Johnson Space Center take astronauts out for field mapping exercises so that they can better recognize and understand features and processes that they will later observe from the International Space Station. Using pre-storm baseline images of the Bolivar Peninsula near Rollover Pass and Gilchrist (NOAA/Google Earth Imagery and USGS aerial imagery and lidar data), the astronauts mapped current coastline positions at defined locations, and related their findings to specific coastal characteristics, including channel, jetties, and other developments. In addition to mapping, we dug trenches along both the Gulf of Mexico coast as well as the Galveston Bay coast of the Bolivar peninsula to determine the depth of the scouring from the storm on the Gulf side, and the amount of deposition of the storm surge deposits on the Bay side of the peninsula. The storm signature was easy to identify by sharp sediment transitions and, in the case of storm deposits, a layer of storm debris (roof shingles, PVC pipes, etc) and black, organic rich layers containing buried sea grasses in areas that were marshes before the storm. The amount of deposition was generally about 20-25 cm; the local areas experiencing obvious deposition are readily obvious in post-Ike imagery of the region. We used a March 2010 aerial photograph from the NOAA-Google Earth collection because construction and vegetation recovery was minimal. Based on the before and after aerial imagery and the trenching data collected over two days, we can begin to characterize the material transported and deposited by Hurricane Ike along one stretch of the Bolivar peninsula. We summarize the results from our mapping and trenching data. The basic data collected 2.5 years after the storm are ephemeral as the storm deposits become reworked and overprinted by coastal processes, vegetation regrowth and reconstruction.

Hurricane Ike Deposits on the Bolivar Peninsula, Galveston Bay, Texas

NASA Technical Reports Server (NTRS)

Evans, Cynthia A.; Wilkinson, M. J.; Eppler, Dean

2011-01-01

In September 2008, Hurricane Ike made landfall on Galveston Bay, close to the NASA Johnson Space Center (JSC). The storm flooded much of the area with a storm surge ranging from 11 -20 feet. The Bolivar peninsula, the southeastern coast of Galveston Bay, experienced the brunt of the surge. Several agencies collected excellent imagery baselines before the storm and complementary data a few days afterward that helped define the impacts of the storm. In April of 2011, a team of scientists and astronauts from JSC conducted field mapping exercises along the Bolivar Peninsula, the section of the Galveston Bay coast most impacted by the storm. Astronauts routinely observe and document coastal changes from orbit aboard the International Space Station. As part of their basic Earth Science training, scientists at the Johnson Space Center take astronauts out for field mapping exercises so that they can better recognize and understand features and processes that they will later observe from the International Space Station. Using pre -storm baseline images of the Bolivar Peninsula near Rollover Pass and Gilchrist (NOAA/Google Earth Imagery and USGS aerial imagery and lidar data), the astronauts mapped current coastline positions at defined locations, and related their findings to specific coastal characteristics, including channel, jetties, and other developments. In addition to mapping, we dug trenches along both the Gulf of Mexico coast as well as the Galveston Bay coast of the Bolivar peninsula to determine the depth of the scouring from the storm on the Gulf side, and the amount of deposition of the storm surge deposits on the Bay side of the peninsula. The storm signature was easy to identify by sharp sediment transitions and, in the case of storm deposits, a layer of storm debris (roof shingles, PVC pipes, etc) and black, organic rich layers containing buried sea grasses in areas that were marshes before the storm. The amount of deposition was generally about 20 -25 cm; the local areas experiencing obvious deposition are readily obvious in post -Ike imagery of the region. We used a March 2010 aerial photograph from the NOAA -Google Earth collection because construction and vegetation recovery was minimal. Based on the before and after aerial imagery and the trenching data collected over two days, we can begin to characterize the material transported and deposited by Hurricane Ike along one stretch of the Bolivar peninsula. We summarize the results from our mapping and trenching data. The basic data collected 2.5 years after the storm are ephemeral as the storm deposits become reworked and overprinted by coastal processes, vegetation regrowth and reconstruction.

Estimates of suspended-sediment flux and bedform activity on the inner portion of the Eel continental shelf

USGS Publications Warehouse

Cacchione, D.A.; Wiberg, P.L.; Lynch, J.; Irish, J.; Traykovski, P.

1999-01-01

Energetic waves, strong bottom currents, and relatively high rates of sediment discharge from the Eel River combined to produce large amounts of suspended-sediment transport on the inner continental shelf near the Eel River during the winter of 1995-1996. Bottom-boundary-layer (BBL) measurements at a depth of ~50 m using the GEOPROBE tripod showed that the strongest near-bottom flows (combined wave and current speeds of over 1 m/s) and highest sediment concentrations (exceeding 2 g/l at ~1.2 m above the bed) occurred during two storms, one in December 1995 and the other in February 1996. Discharge from the Eel River during these storms was estimated at between 2 and 4 x 103 m3/s. Suspended-sediment flux (SSF) was measured 1.2 m above the bed and calculated throughout the BBL, by applying the tripod data to a shelf sediment-transport model. These results showed initially northward along-shelf SSF during the storms, followed by abrupt and persistent southward reversals. Along-shelf flux was more pronounced during and after the December storm than in February. Across-shelf SSF over the entire measurement period was decidedly seaward. This seaward transport could be responsible for surficial deposits of recent sediment on the outer shelf and upper continental slope in this region. Sediment ripples and larger bedforms were observed in the very fine to fine sand at 50-m depth using a sector-scanning sonar mounted on the tripod. Ripple wavelengths estimated from the sonar images were about 9 cm, which compared favorably with photographs of the bottom taken with a camera mounted on the tripod. The ripple patterns were stable during periods of low combined wave-current bottom stresses, but changed significantly during high-stress events, such as the February storm. Two different sonic altimeters recorded changes in bed elevation of 10 to 20 cm during the periods of measurement. These changes are thought to have been caused principally by the migration of low-amplitude, long-wavelength sand waves into the measurement area.

Storm-driven Mixing and Potential Impact on the Arctic Ocean

NASA Technical Reports Server (NTRS)

Yang, Jiayan; Comiso, Josefino; Walsh, David; Krishfield, Richard; Honjo, Susumu; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Observations of the ocean, atmosphere, and ice made by Ice-Ocean Environmental Buoys (IOEBs) indicate that mixing events reaching the depth of the halocline have occurred in various regions in the Arctic Ocean. Our analysis suggests that these mixing events were mechanically forced by intense storms moving across the buoy sites. In this study, we analyzed these mixing events in the context of storm developments that occurred in the Beaufort Sea and in the general area just north of Fram Strait, two areas with quite different hydrographic structures. The Beaufort Sea is strongly influenced by inflow of Pacific water through Bering Strait, while the area north of Fram Strait is directly affected by the inflow of warm and salty North Atlantic water. Our analyses of the basin-wide evolution of the surface pressure and geostrophic wind fields indicate that the characteristics of the storms could be very different. The buoy-observed mixing occurred only in the spring and winter seasons when the stratification was relatively weak. This indicates the importance of stratification, although the mixing itself was mechanically driven. We also analyze the distribution of storms, both the long-term climatology as well as the patterns for each year in the last two decades. The frequency of storms is also shown to be correlated- (but not strongly) to Arctic Oscillation indices. This study indicates that the formation of new ice that leads to brine rejection is unlikely the mechanism that results in the type of mixing that could overturn the halocline. On the other hand, synoptic-scale storms can force mixing deep enough to the halocline and thermocline layer. Despite a very stable stratification associated with the Arctic halocline, the warm subsurface thermocline water is not always insulated from the mixed layer.

Assessing Cost-effectiveness of Green Infrastructures in response to Large Storm Events at Household Scale

NASA Astrophysics Data System (ADS)

Chui, T. F. M.; Liu, X.; Zhan, W.

2015-12-01

Green infrastructures (GI) are becoming more important for urban stormwater control worldwide. However, relatively few studies focus on researching the specific designs of GI at household scale. This study assesses the hydrological performance and cost-effectiveness of different GI designs, namely green roofs, bioretention systems and porous pavements. It aims to generate generic insights by comparing the optimal designs of each GI in 2-year and 50-year storms of Hong Kong, China and Seattle, US. EPA SWMM is first used to simulate the hydrologic performance, in particular, the peak runoff reduction of thousands of GI designs. Then, life cycle costs of the designs are computed and their effectiveness, in terms of peak runoff reduction percentage per thousand dollars, is compared. The peak runoff reduction increases almost linearly with costs for green roofs. However, for bioretention systems and porous pavements, peak runoff reduction only increases significantly with costs in the mid values. For achieving the same peak runoff reduction percentage, the optimal soil depth of green roofs increases with the design storm, while surface area does not change significantly. On the other hand, for bioretention systems and porous pavements, the optimal surface area increases with the design storm, while thickness does not change significantly. In general, the cost effectiveness of porous pavements is highest, followed by bioretention systems and then green roofs. The cost effectiveness is higher for a smaller storm, and is thus higher for 2-year storm than 50-year storm, and is also higher for Seattle when compared to Hong Kong. This study allows us to better understand the hydrological performance and cost-effectiveness of different GI designs. It facilitates the implementation of optimal choice and design of each specific GI for stormwater mitigation.

A Study of Oceans and Atmospheric Interactions Associated with Tropical Cyclone Activity using Earth Observing Technology

NASA Astrophysics Data System (ADS)

Abdullah, Warith; Reddy, Remata

From October 22nd to 30th, 2012 Hurricane Sandy was a huge storm of many abnormalities causing an estimated 50 billion dollars in damage. Tropical storm development states systems’ energy as product of warm sea surface temperatures (SST’s) and tropical cyclone heat potential (TCHP). Advances in Earth Observing (EO) technology, remote sensing and proxy remote sensing have allowed for accurate measurements of SST and TCHP information. In this study, we investigated rapid intensification of Sandy through EO applications for precipitable water vapor (PWAT), SST’s and TCHP during the period of October 27th. These data were obtained from NASA and NOAA satellites and NOAA National Buoy data center (NDBC). The Sensible Heat (Qs) fluxes were computed to determine available energy resulting from ocean-atmosphere interface. Buoy 41010, 120 NM east of Cape Canaveral at 0850 UTC measured 22.3 °C atmospheric temperatures and 27 °C SST, an interface of 4.7 °C. Sensible heat equation computed fluxes of 43.7 W/m2 at 982.0 mb central pressure. Sandy formed as late-season storm and near-surface air temperatures averaged > 21 °C according to NOAA/ESRL NCEP/NCAR reanalysis at 1000 mb and GOES 13 (EAST) geostationary water vapor imagery shows approaching cold front during October 27th. Sandy encountered massive dry air intrusion to S, SE and E quadrants of storm while travelling up U.S east coast but experienced no weakening. Cool, dry air intrusion was considered for PWAT investigation from closest sounding station during Oct. 27th 0900 - 2100 UTC at Charleston, SC station 72208. Measured PWAT totaled 42.97 mm, indicating large energy potential supply to the storm. The Gulf Stream was observed using NASA Short-term Prediction Research and Transition Center (SPoRT) MODIS SST analysis. The results show 5 °C warmer above average than surrounding cooler water, with > 25 °C water extent approximately 400 NM east of Chesapeake Bay and eddies > 26 °C. Results from sensible heat computations for atmospheric interface suggests unusual warmth associated with Gulf Stream current, such that it provided Sandy with enough kinetic energy to intensify at high latitude. The study further suggests that energy gained from Caribbean TCHP and Gulf Stream SST’s were largely retained by Sandy upon losing tropical-cyclone characteristics and merging with strong cold front and polar jet stream. Storms of Sandy’s magnitude and unusual source of energy resulting from Gulf Stream may indicate a building average for tropical cyclone development and intensity for North Atlantic, particularly as the GOM waters continue to warm on seasonal averages.

Analysis of Storm Surge in Hong Kong

NASA Astrophysics Data System (ADS)

Kao, W. H.

2017-12-01

A storm surge is a type of coastal flood that is caused by low-pressure systems such as tropical cyclones. Storm surges caused by tropical cyclones can be very powerful and damaging, as they can flood coastal areas, and even destroy infrastructure in serious cases. Some serious cases of storm surges leading to more than thousands of deaths include Hurricane Katrina (2005) in New Orleans and Typhoon Haiyan (2013) in Philippines. Hong Kong is a coastal city that is prone to tropical cyclones, having an average of 5-6 tropical cyclones entering 500km range of Hong Kong per year. Storm surges have seriously damaged Hong Kong in the past, causing more than 100 deaths by Typhoon Wanda (1962), and leading to serious damage to Tai O and Cheung Chau by Typhoon Hagupit (2008). To prevent economic damage and casualties from storm surges, accurately predicting the height of storm surges and giving timely warnings to citizens is very important. In this project, I will be analyzing how different factors affect the height of storm surge, mainly using data from Hong Kong. These factors include the windspeed in Hong Kong, the atmospheric pressure in Hong Kong, the moon phase, the wind direction, the intensity of the tropical cyclone, distance between the tropical cyclone and Hong Kong, the direction of the tropical cyclone relative to Hong Kong, the speed of movement of the tropical cyclone and more. My findings will also be compared with cases from other places, to see if my findings also apply for other places.

Precipitation records and flood-producing storms in Cheyenne, Wyoming

USGS Publications Warehouse

Lindner-Lunsford, J. B.

1988-01-01

Annual maximum precipitation data for Cheyenne, Wyoming, are presented for the years 1871-1986 for durations of 5, 10, 15, and 30 minutes and 1, 2, and 24 hours. Precipitation-frequency curves are developed on the basis of data collected before 1985; a second set of curves are developed on the basis of data collected through 1986. The data are plotted and analyzed three times, assuming: (1) The data are described by a Gumbel distribution; (2) the logarithms of the data are described by a Gumbel distribution; and (3) the logarithms of the data are described by a Pearson Type III distribution. The inclusion of data for the large storm of August 1, 1985, had the most noticeable effect on the prediction of the magnitude of storms of long average recurrence intervals for the 1-, 2-, and 24-hour durations. Seven intensity-duration curves were calculated for the August 1, 1985 storm. For durations greater than 30 minutes, the observed curve indicates greater intensity than do five of the seven calculated curves. Dimensionless hyetographs were developed for 10 flood-producing storms that have occurred in the Cheyenne area since 1903. The pattern index (integral of the dimensionless hyetograph curve) for the storm of August 1, 1985, is 3 standard deviations lower than the mean of the pattern indices for the remaining 9 storms, indicating that the distribution of precipitation with time for the August 1, 1985, storm was outside the normal range for Cheyenne. (USGS)

Atmospheric inputs of organic matter to a forested watershed: Variations from storm to storm over the seasons

NASA Astrophysics Data System (ADS)

Iavorivska, Lidiia; Boyer, Elizabeth W.; Miller, Matthew P.; Brown, Michael G.; Vasilopoulos, Terrie; Fuentes, Jose D.; Duffy, Christopher J.

2016-12-01

The objectives of this study were to determine the quantity and chemical composition of precipitation inputs of dissolved organic carbon (DOC) to a forested watershed; and to characterize the associated temporal variability. We sampled most precipitation that occurred from May 2012 through August 2013 at the Susquehanna Shale Hills Critical Zone Observatory (Pennsylvania, USA). Sub-event precipitation samples (159) were collected sequentially during 90 events; covering various types of synoptic meteorological conditions in all climatic seasons. Precipitation DOC concentrations and rates of wet atmospheric DOC deposition were highly variable from storm to storm, ranging from 0.3 to 5.6 mg C L-1 and from 0.5 to 32.8 mg C m-2 h-1, respectively. Seasonally, storms in spring and summer had higher concentrations of DOC and more optically active organic matter than in winter. Higher DOC concentrations resulted from weather types that favor air advection, where cold frontal systems, on average, delivered more than warm/stationary fronts and northeasters. A mixed modeling statistical approach revealed that factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in dissolved organic matter that can be useful in modeling of atmospheric oxidative chemistry, exploring relationships between organics and other elements of precipitation chemistry, and in considering temporal changes in ecosystem nutrient balances and microbial activity.

Resolution Dependence of Future Tropical Cyclone Projections of CAM5.1 in the U.S. CLIVAR Hurricane Working Group Idealized Configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehner, Michael; ., Prabhat; Reed, Kevin A.

The four idealized configurations of the U.S. CLIVAR Hurricane Working Group are integrated using the global Community Atmospheric Model version 5.1 at two different horizontal resolutions, approximately 100 and 25 km. The publicly released 0.9° × 1.3° configuration is a poor predictor of the sign of the 0.23° × 0.31° model configuration’s change in the total number of tropical storms in a warmer climate. However, it does predict the sign of the higher-resolution configuration’s change in the number of intense tropical cyclones in a warmer climate. In the 0.23° × 0.31° model configuration, both increased CO 2 concentrations and elevatedmore » sea surface temperature (SST) independently lower the number of weak tropical storms and shorten their average duration. Conversely, increased SST causes more intense tropical cyclones and lengthens their average duration, resulting in a greater number of intense tropical cyclone days globally. Increased SST also increased maximum tropical storm instantaneous precipitation rates across all storm intensities. It was found that while a measure of maximum potential intensity based on climatological mean quantities adequately predicts the 0.23° × 0.31° model’s forced response in its most intense simulated tropical cyclones, a related measure of cyclogenesis potential fails to predict the model’s actual cyclogenesis response to warmer SSTs. These analyses lead to two broader conclusions: 1) Projections of future tropical storm activity obtained by a direct tracking of tropical storms simulated by coarse-resolution climate models must be interpreted with caution. 2) Projections of future tropical cyclogenesis obtained from metrics of model behavior that are based solely on changes in long-term climatological fields and tuned to historical records must also be interpreted with caution.« less

Erosion under extreme climatic events in tropical climates : the case of the storm Helena (1963) in the Guadeloupe island (Lesser Antilles Arc)

NASA Astrophysics Data System (ADS)

Allemand, P.; Lajeunesse, E.; Devauchelle, O.; Delacourt, C.

2012-04-01

he volume of sediment exported from a tropical watershed is dramatically increased during extreme climatic events, such as storms and tropical cyclones (Dadson et al. 2004; Hilton et al. 2008). Indeed, the exceptionally high rainfall rates reached during these events generate runoff and trigger landslides which accumulate a significant amount of sediments in flooded rivers (Gabet et al., 2004; Lin et al., 2008). We estimate the volume of sediments mobilized by the storm Helena (26 to 28 October 1963) on Basse-Terre Island in the archipelago of Guadeloupe. This is achieved using images acquired by IGN (Institut Géographique National) a few weeks after the storm which produced numerous landslides. All the available images from this campaign have been pseudo-orthorectified and included in a GIS with a Digital Elevation Model with a resolution of 10 m. Two hundred fifty three landslides have been identified and mapped. Most of them are located in the center of the island, where the highest slopes are. The cumulated surface of the landslides is 0.5 km2. Field observations on Basse-Terre show that landslides mobilized the whole regolith layer, which is about 1m thick. Assuming an average landslide thickness of 1m, we find that the total volume of sediment mobilized by the storm Helena is 0.5 km3. The associated denudation averaged over all watersheds affected by landslides is 1.4 mm with a maximum of 5 mm for the watersheds of Vieux-Habitants and Capesterre. The impact of the storm Helena is then discussed with respect to 1) the erosion induced on the Capesterre catchment by the highest flood available in a two years survey record (less than 0.1 mm/y); 2) the long term denudation rate of the major watersheds of Basse-Terre estimated by reconstructing the initial volcanic topography (between 0.1 and 0.4 mm/y).

Resolution Dependence of Future Tropical Cyclone Projections of CAM5.1 in the U.S. CLIVAR Hurricane Working Group Idealized Configurations

DOE PAGES

Wehner, Michael; ., Prabhat; Reed, Kevin A.; ...

2015-05-12

The four idealized configurations of the U.S. CLIVAR Hurricane Working Group are integrated using the global Community Atmospheric Model version 5.1 at two different horizontal resolutions, approximately 100 and 25 km. The publicly released 0.9° × 1.3° configuration is a poor predictor of the sign of the 0.23° × 0.31° model configuration’s change in the total number of tropical storms in a warmer climate. However, it does predict the sign of the higher-resolution configuration’s change in the number of intense tropical cyclones in a warmer climate. In the 0.23° × 0.31° model configuration, both increased CO 2 concentrations and elevatedmore » sea surface temperature (SST) independently lower the number of weak tropical storms and shorten their average duration. Conversely, increased SST causes more intense tropical cyclones and lengthens their average duration, resulting in a greater number of intense tropical cyclone days globally. Increased SST also increased maximum tropical storm instantaneous precipitation rates across all storm intensities. It was found that while a measure of maximum potential intensity based on climatological mean quantities adequately predicts the 0.23° × 0.31° model’s forced response in its most intense simulated tropical cyclones, a related measure of cyclogenesis potential fails to predict the model’s actual cyclogenesis response to warmer SSTs. These analyses lead to two broader conclusions: 1) Projections of future tropical storm activity obtained by a direct tracking of tropical storms simulated by coarse-resolution climate models must be interpreted with caution. 2) Projections of future tropical cyclogenesis obtained from metrics of model behavior that are based solely on changes in long-term climatological fields and tuned to historical records must also be interpreted with caution.« less

Examining Hurricane Track Length and Stage Duration Since 1980

NASA Astrophysics Data System (ADS)

Fandrich, K. M.; Pennington, D.

2017-12-01

Each year, tropical systems impact thousands of people worldwide. Current research shows a correlation between the intensity and frequency of hurricanes and the changing climate. However, little is known about other prominent hurricane features. This includes information about hurricane track length (the total distance traveled from tropical depression through a hurricane's final category assignment) and how this distance may have changed with time. Also unknown is the typical duration of a hurricane stage, such as tropical storm to category one, and if the time spent in each stage has changed in recent decades. This research aims to examine changes in hurricane stage duration and track lengths for the 319 storms in NOAA's National Ocean Service Hurricane Reanalysis dataset that reached Category 2 - 5 from 1980 - 2015. Based on evident ocean warming, it is hypothesized that a general increase in track length with time will be detected, thus modern hurricanes are traveling a longer distance than past hurricanes. It is also expected that stage durations are decreasing with time so that hurricanes mature faster than in past decades. For each storm, coordinates are acquired at 4-times daily intervals throughout its duration and track lengths are computed for each 6-hour period. Total track lengths are then computed and storms are analyzed graphically and statistically by category for temporal track length changes. The stage durations of each storm are calculated as the time difference between two consecutive stages. Results indicate that average track lengths for Cat 2 and 3 hurricanes are increasing through time. These findings show that these hurricanes are traveling a longer distance than earlier Cat 2 and 3 hurricanes. In contrast, average track lengths for Cat 4 and 5 hurricanes are decreasing through time, showing less distance traveled than earlier decades. Stage durations for all Cat 2, 4 and 5 storms decrease through the decades but Cat 3 storms show a positive increase though time. This compliments the results of the track length analysis indicating that as storms intensify faster, they are doing so over a shorter distance. It is expected that this research could be used to improve hurricane track forecasting and provide information about the effects of climate change on tropical systems and the tropical environment.

Geomagnetic storm under laboratory conditions: randomized experiment

NASA Astrophysics Data System (ADS)

Gurfinkel, Yu I.; Vasin, A. L.; Pishchalnikov, R. Yu; Sarimov, R. M.; Sasonko, M. L.; Matveeva, T. A.

2017-10-01

The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

Geomagnetic storm under laboratory conditions: randomized experiment.

PubMed

Gurfinkel, Yu I; Vasin, A L; Pishchalnikov, R Yu; Sarimov, R M; Sasonko, M L; Matveeva, T A

2018-04-01

The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

Influence of recharge basins on the hydrology of Nassau and Suffolk Counties, Long Island, New York

USGS Publications Warehouse

Seaburn, G.E.; Aronson, D.A.

1974-01-01

An investigation of recharge basins on Long Island was made by the U.S. Geological Survey in cooperation with the New York State Department of Environmental Conservation, Nassau County Department of Public Works, Suffolk County Department of Environmental Control, and Suffolk County Water Authority. The major objectives of the study were to (1) catalog basic physical data on the recharge basins in use on Long Island, (2) measure quality and quantity of precipitation and inflow, (3) measure infiltration rates at selected recharge basins, and (4) evaluate regional effects of recharge basins on the hydrologic system of Long Island. The area of study consists of Nassau and Suffolk Counties -- about 1,370 square miles -- in eastern Long Island, N.Y. Recharge basins, numbering more than 2,100 on Long Island in 1969, are open pits in moderately to highly permeable sand and gravel deposits. These pits are used to dispose of storm runoff from residential, industrial, and commercial areas, and from highways, by infiltration of the water through the bottom and sides of the basins. The hydrology of three recharge basins on Long Island -- Westbury, Syosset, and Deer Park basins -- was studied. The precipitation-inflow relation showed that the average percentages of precipitation flowing into each basin were roughly equivalent to the average percentages of impervious areas in the total drainage areas of the basins. Average percentages of precipitation flowing into the basins as direct runoff were 12 percent at the Westbury basin, 10 percent at the Syosset basin, and 7 percent at the Deer Park basin. Numerous open-bottomed storm-water catch basins at Syosset and Deer Park reduced the proportion of inflow to those basins, as compared with the Westbury basin, which has only a few open-bottomed catch basins. Inflow hydrographs for each basin typify the usual urban runoff hydrograph -- steeply rising and falling limbs, sharp peaks, and short time bases. Unit hydrographs for the Westbury and the Syosset basins are not expected to change; however, the unit hydrograph for the Deer Park basin is expected to broaden somewhat as a result of additional future house construction within the drainage area. Infiltration rates averaged 0.9 fph (feet per hour) for 63 storms between July 1967 and May 1970 at the Westbury recharge basin, 0.8 fph for 22 storms from July 1969 to September 1970 at the Syosset recharge basin, and 0.2 fph for 24 storms from March to September 1970 at the Deer Park recharge basin. Low infiltration rates at Deer Park resulted mainly from (1) a high percentage of eroded silt, clay, and organic debris washed in from construction sites in the drainage area, which partly filled the interstices of the natural deposits, and (2) a lack of a well-developed plant-root system on the floor of the younger basin, which would have kept the soil zone more permeable. The apparent rate of movement of storm water through the unsaturated zone below each basin averaged 5.5 fph at Westbury, 3.7 fph at Syosset, and 3.1 fph at Deer Park. The rates of movement for storms during the warm months (April through October) were slightly higher than average, probably because the recharging water was warmer than it was during the rest of the year, and therefore, was slightly less viscous. On the average, a 1-inch rainfall resulted in a peak rise of the water table directly below each basin of 0.5 foot; a 2-inch rainfall resulted in a peak rise of about 2 feet. The mound commonly dissipated within 1 to 4 days at Westbury, 7 days to more than 15 days at Syosset, and 1 to 3 days at Deer Park, depending on the magnitude of the peak buildup. Average annual ground-water recharge was estimated to be 6.4 acre-feet at the Westbury recharge basin, 10.3 acre-feet at the Syosset recharge basin, and 29.6 acre-feet at the Deer Park recharge basin. Chemical composition of precipitation at Westbury, Syosset, and Deer Park drainage areas was similar:

Coastal emergency managers' preferences for storm surge forecast communication.

PubMed

Morrow, Betty Hearn; Lazo, Jeffrey K

2014-01-01

Storm surge, the most deadly hazard associated with tropical and extratropical cyclones, is the basis for most evacuation decisions by authorities. One factor believed to be associated with evacuation noncompliance is a lack of understanding of storm surge. To address this problem, federal agencies responsible for cyclone forecasts are seeking more effective ways of communicating storm surge threat. To inform this process, they are engaging various partners in the forecast and warning process.This project focuses on emergency managers. Fifty-three emergency managers (EMs) from the Gulf and lower Atlantic coasts were surveyed to elicit their experience with, sources of, and preferences for storm surge information. The emergency managers-who are well seasoned in hurricane response and generally rate the surge risk in their coastal areas above average or extremely high-listed storm surge as their major concern with respect to hurricanes. They reported a general lack of public awareness about surge. Overall they support new ways to convey the potential danger to the public, including the issuance of separate storm surge watches and warnings, and the expression of surge heights using feet above ground level. These EMs would like more maps, graphics, and visual materials for use in communicating with the public. An important concern is the timing of surge forecasts-whether they receive them early enough to be useful in their evacuation decisions.

Climate change, atmospheric rivers, and floods in California - a multimodel analysis of storm frequency and magnitude changes

USGS Publications Warehouse

Dettinger, M.

2011-01-01

Recent studies have documented the important role that "atmospheric rivers" (ARs) of concentrated near-surface water vapor above the Pacific Ocean play in the storms and floods in California, Oregon, and Washington. By delivering large masses of warm, moist air (sometimes directly from the Tropics), ARs establish conditions for the kinds of high snowlines and copious orographic rainfall that have caused the largest historical storms. In many California rivers, essentially all major historical floods have been associated with AR storms. As an example of the kinds of storm changes that may influence future flood frequencies, the occurrence of such storms in historical observations and in a 7-model ensemble of historical-climate and projected future climate simulations is evaluated. Under an A2 greenhouse-gas emissions scenario (with emissions accelerating throughout the 21st Century), average AR statistics do not change much in most climate models; however, extremes change notably. Years with many AR episodes increase, ARs with higher-than-historical water-vapor transport rates increase, and AR storm-temperatures increase. Furthermore, the peak season within which most ARs occur is commonly projected to lengthen, extending the flood-hazard season. All of these tendencies could increase opportunities for both more frequent and more severe floods in California under projected climate changes. ?? 2011 American Water Resources Association.

Hydro morphodynamic modelling in Mediterranean storms: errors and uncertainties under sharp gradients

NASA Astrophysics Data System (ADS)

Sánchez-Arcilla, A.; Gracia, V.; García, M.

2014-02-01

This paper deals with the limits in hydrodynamic and morphodynamic predictions for semi-enclosed coastal domains subject to sharp gradients (in bathymetry, topography, sediment transport and coastal damages). It starts with an overview of wave prediction limits (based on satellite images) in a restricted domain such as is the Mediterranean basin, followed by an in-depth analysis of the Catalan coast, one of the land boundaries of such a domain. The morphodynamic modeling for such gradient regions is next illustrated with the simulation of the largest recorded storm in the Catalan coast, whose morphological impact is a key element of the storm impact. The driving wave and surge conditions produce a morphodynamic response that is validated against the pre and post storm beach state, recovered from two LIDAR images. The quality of the fit is discussed in terms of the physical processes and the suitability of the employed modeling equations. Some remarks about the role of the numerical discretization and boundary conditions are also included in the analysis. From here an assessment of errors and uncertainties is presented, with the aim of establishing the prediction limits for coastal engineering flooding and erosion analyses.

Sensitivity of storm wave modeling to wind stress evaluation methods

NASA Astrophysics Data System (ADS)

Chen, Yingjian; Yu, Xiping

2017-06-01

The application of the wave boundary layer model (WBLM) for wind stress evaluation to storm wave modeling is studied using Hurricane Katrina (2005) as an example, which is chosen due to its great intensity and good availability of field data. The WBLM is based on the momentum and energy conservation equations and takes into account the physical details of air-sea interaction processes as well as energy dissipation due to the presence of sea spray. Four widely-used bulk-type formulas are also used for comparison. Simulated significant wave heights with WBLM are shown to agree well with the observed data over deep water. The WBLM yields a smaller wind stress coefficient on the left hand side of the hurricane track, which is reasonable considering the effect of the sea state on momentum transfer. Quantitative results show that large differences of the significant wave height are observed in the hurricane core among five wind stress evaluation methods and the differences are up to 12 m, which is in agreement with the general knowlege that the ocean dynamic processes under storm conditions are very sensitive to the amount of momentum exchange at the air-sea interface. However, it is the depth-induced energy dissipation, rather than the wind energy input, that dominates the wave height in the shallow water region. A larger value of depth-induced breaking parameter in the wave model results in better agreement with the measurements over shallow water.

Airborne dust absorption by semi-arid forests reduces PM pollution in nearby urban environments.

PubMed

Uni, Daphna; Katra, Itzhak

2017-11-15

Dust storms are a major source of global atmospheric particulate matter (PM), having significant impacts on air pollution and human health. During dust storms, daily averages of atmospheric PM concentrations can reach high levels above the World Health Organization (WHO) guideline for air quality. The objective of this study was to explore the impact of forests on PM distribution following dust events in a region that is subjected to frequent dust storms (Northern Negev, Israel). Dust was measured in a forest transect including urban environments that are nearby the forest and at a distal location. During a background period, without dust events, the forest with its surrounding areas were characterized by lower monthly average of PM concentrations (38μg/m 3 ) compared with areas that are not affected by the forest (54μg/m 3 ). Such difference can be meaningful for long-term human health exposure. A reduction in PM levels in the forest transect was evident at most measured dust events, depending on the storm intensity and the locations of the protected areas. A significant reduction in PM 2.5 /PM 10 during dust events, indicates the high efficiency of the forest trees to absorb airborne PM 2.5 . Analysis of dust particles absorbed on the foliage revealed a total dust deposits of 8.1-9.2g/m 2 , which is equal to a minimum of 418.2tons removed from the atmosphere per a forest foliage area (30km 2 ). The findings can support environmental strategies to enhance life quality in regions that are subjected to dust storms, or under potential risk of dust-related PM due to land use and/or climate changes. Copyright © 2017 Elsevier B.V. All rights reserved.

The ionospheric response to the Saint Patrick storm over South East Asia

NASA Astrophysics Data System (ADS)

Spogli, L.; Alfonsi, L.; Di Mauro, D.; Pezzopane, M.; Cesaroni, C.; Povero, G., Sr.; Pini, M., Sr.; Dovis, F., Sr.; Romero, R.; Linty, N.; Abadi, P.; Nuraeni, F.; Husin, A.; Huy Le, M.; La The, V.; Pillat, V. G.; Floury, N.

2015-12-01

ERICA, a project funded by the European Space Agency, aims at characterizing the ionospheric variability of the Equatorial Ionospheric Anomaly in the South East Asia. In particular, ERICA focuses on the variation of the plasma electron density in the southern and northern crests of the anomaly and over the dip equator identified by the Equatorial Ionospheric Trough. To achieve this goal, an ad hoc measurements campaign is on-going with ground-based instruments located in the footprints of the Equatorial Ionospheric Anomaly and of the Equatorial Ionospheric Trough in Vietnam and Indonesia.The campaign started on the 1st of March 2015, timing to monitor the Saint Patrick storm effects on the ionosphere by means of ionosondes, double frequency hardware and software defined radio GNSS receivers, ground based and spaceborne magnetometers and Langmuir probe. Such multi-instrumental and multi-parametric observations of the region enables an in-depth investigation of the ionospheric response to the largest geomagnetic storm of the current solar cycle. The observations record positive and negative ionospheric storms, sporadic E layer and spread F conditions, scintillations enhancement and inhibition, TEC gradients. The ancillary information on the local magnetic field allows to highlight the variety of ionospheric perturbations happened during the main and the long recovery phase of the storm.The paper presents the outcomes of the investigation evidencing the peculiarities of a region not yet extensively reported in the open literature.

Biogeochemical responses of arctic hillslopes to storms and seasonal thaw

NASA Astrophysics Data System (ADS)

Harms, T.

2015-12-01

Resilience of watersheds includes maintenance of biogeochemical functions, including retention and transport of solutes, following perturbations. In the arctic, important perturbations that may result in departure from the current state of watersheds include gradual or catastrophic loss of permafrost, increasing temperature, and increased intensity of storms. However, these long-term changes are occurring against the backdrop of variation introduced by seasonality and storms. Thus, establishing baselines that capture temporal patterns is an essential step in predicting vulnerability of arctic watersheds to climate-induced change. We have documented temporal patterns in solute concentrations of six water tracks, zero-order channels that drain arctic hillslopes. Temporal patterns were typically site-specific, underscoring the value of watershed monitoring for predicting responses to perturbations. In some catchments, peak export of organic carbon, nitrogen, and phosphorus occurred during snowmelt, whereas in others, flushing during storms yielded greater export. Concentrations of non-limiting inorganic solutes (e.g., sulfate, calcium) increased through the thaw period in some catchments, suggesting that these solutes may serve as indicators of degrading permafrost. We observed a decrease in the magnitude of flushing of biolabile solutes (e.g., ammonium, organic carbon) during storms through the thaw season, reflecting hydrologic disconnection of upper, organic soils as thaw depth increases and flowpaths deepen. The observed patterns establish a template of temporal variation against which future observations may be assessed to evaluate departures from a stable state.

Coast of California Storm and Tidal Waves Study.

DTIC Science & Technology

1986-07-01

Nee0y d Identify by block mbr ) THIS IS THE THIRD ANNUAL REPORT OF THE CORPS OF ENGINEERS’ LANDMARK STUDY OF THE COAST OF CALIFORNIA. IT IS A REPORT...rods driven into the bottom and by measuring changes in depth from submerged reference lines. In addition, sediment traps are fastened to canyon walls

Developing empirical lightning cessation forecast guidance for the Kennedy Space Center

NASA Astrophysics Data System (ADS)

Stano, Geoffrey T.

The Kennedy Space Center in east Central Florida is one of the few locations in the country that issues lightning advisories. These forecasts are vital to the daily operations of the Space Center and take on even greater significance during launch operations. The U.S. Air Force's 45th Weather Squadron (45WS), who provides forecasts for the Space Center, has a good record of forecasting the initiation of lightning near their locations of special concern. However, the remaining problem is knowing when to cancel a lightning advisory. Without specific scientific guidelines detailing cessation activity, the Weather Squadron must keep advisories in place longer than necessary to ensure the safety of personnel and equipment. This unnecessary advisory time costs the Space Center millions of dollars in lost manpower each year. This research presents storm and environmental characteristics associated with lightning cessation that then are utilized to create lightning cessation guidelines for isolated thunderstorms for use by the 45WS during the warm season months of May through September. The research uses data from the Lightning Detection and Ranging (LDAR) network at the Kennedy Space Center, which can observe intra-cloud and portions of cloud-to-ground lightning strikes. Supporting data from the Cloud-to-Ground Lightning Surveillance System (CGLSS), radar observations from the Melbourne WSR-88D, and Cape Canaveral morning radiosonde launches also are included. Characteristics of 116 thunderstorms comprising our dataset are presented. Most of these characteristics are based on LDAR-derived spark and flash data and have not been described previously. In particular, the first lightning activity is quantified as either cloud-to-ground (CG) or intra-cloud (IC). Only 10% of the storms in this research are found to initiate with a CG strike. Conversely, only 16% of the storms end with a CG strike. Another characteristic is the average horizontal extent of all the flashes comprising a storm. Our average is 12-14 km, while the greatest flash extends 26 km. Comparisons between the starting altitude of the median and last flashes of a storm are analyzed, with only 37% of the storms having a higher last flash initiating altitude. Additional observations are made of the total lightning flash rate, percentage of CG to IC lightning, trends of individual flash initiation altitudes versus the average initiation altitude, the average inter-flash time distribution, and time series of inter-flash times. Five schemes to forecast lightning cessation are developed and evaluated. 100 of the 116 storms were randomly selected as the dependent sample, while the remaining 16 storms were used for verification. The schemes included a correlation and regression tree analysis, multiple linear regression, trends of storm duration, trend of the altitude of the greatest reflectivity to the time of the final flash, and a percentile scheme. Surprisingly, the percentile method was found to be the most effective technique and the simplest. The inclusion of real time storm parameters is found to have little effect on the results, suggesting that different forecast predictors, such as microphysical data from polarimetric radar, will be necessary to produce improved skill. When the percentile method used a confidence level of 99.5%, it successfully maintained lightning advisories for all 16 independent storms on which the schemes were tested. Since the computed wait time was 25 min, compared to the 45WS' most conservative and accurate wait time of 30 min, the percentile method saves 5 min for each advisory. This 5 min of savings safely shortens the Weather Squadron's advisories and saves money. Additionally, these results are the first to evaluate the 30/30 rule that is used commonly. The success of the percentile method is surprising since it out performs more complex procedures involving correlation and regression tree analysis and regression schemes. These more sophisticated statistical analyses were expected to perform better since they include more predictors in the forecasts. However, with the predictors available to us, this was not the case. While not the expected result, the percentile method succeeds in creating a safe and expedited forecast.

Multi-Instrument Investigation of Ionospheric Flow Channels and Their Impact on the Ionosphere and Thermosphere during Geomagnetic Storms

DTIC Science & Technology

2017-12-29

indicated as shaded intervals in cyan) is shown in the context of the 5-6 August 2011 storm energetics. These are depicted by the time series of [b...of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing   data sources...documented in a series of journal articles [Horvath and Lovell, 2017A; 2017B; 2017C; 2017D]. Our findings contribute to the better understanding of

Precipitation patterns and moisture fluxes in a sandy, tropical environment with a shallow water table

NASA Astrophysics Data System (ADS)

Minihane, M. R.; Freyberg, D. L.

2011-08-01

Identifying the dominant mechanisms controlling recharge in shallow sandy soils in tropical climates has received relatively little attention. Given the expansion of coastal fill using marine sands and the growth of coastal populations throughout the tropics, there is a need to better understand the nature of water balances in these settings. We use time series of field observations at a coastal landfill in Singapore coupled with numerical modeling using the Richards' equation to examine the impact of precipitation patterns on soil moisture dynamics, including percolation past the root zone and recharge, in such an environment. A threshold in total precipitation event depth, much more so than peak precipitation intensity, is the strongest event control on recharge. However, shallow antecedent moisture, and therefore the timing between events along with the seasonal depth to water table, also play significant roles in determining recharge amounts. For example, at our field site, precipitation events of less than 3 mm per event yield little to no direct recharge, but for larger events, moisture content changes below the root zone are linearly correlated to the product of the average antecedent moisture content and the total event precipitation. Therefore, water resources planners need to consider identifying threshold precipitation volumes, along with the multiple time scales that capture variability in event antecedent conditions and storm frequency in assessing the role of recharge in coastal water balances in tropical settings.

Southern California Beaches during the El Niño Winter of 2009/2010

NASA Astrophysics Data System (ADS)

Doria, A.; Guza, R. T.; Yates, M. L.; O'Reilly, W.

2010-12-01

Storms during the El Niño winter 2009/2010 produced prolonged periods of energetic waves, and severely eroded southern California beaches. Sand elevations were measured at several beaches over alongshore spans of a few km, for up to 5 years, on cross-shore transects extending from the back beach to about 8 meters depth, and spaced every 100 meters alongshore. Wave conditions were estimated using the CDIP network of directional wave buoys. At the Torrey Pines Outer Buoy, the median significant wave height for January 2010 was the largest for any month in the past 10 year record. Anomalous changes in beach sand level, characterized as the excess volume displaced relative to average-winter profiles, were extreme in both the amount of shoreline erosion and the amount of offshore accretion. Anomalous shoreline erosion volumes were almost twice as large as the second-most severe winter, with vertical deviations as large as -2.3m. Anomalous offshore accretion, in depths between 4-8m and as large as 1.5m vertical, was also exceptional. Beach widths, based on the cross-shore location of the Mean Sea Level (MSL) contour, were narrower than measured in previous winters. The accuracy of shoreline (MSL) location, predicted using an existing shoreline change equilibrium model driven with the estimated waves, will be assessed. Beach recovery, based on ongoing surveys, will also be discussed.

Use of Historical Radar Rainfall Estimates to Develop Design Storms in Los Angeles.

NASA Astrophysics Data System (ADS)

Curtis, D. C.; Humphrey, J.; Moffitt, J.

2007-12-01

A database of 15-minute historical gage adjusted radar-rainfall estimates was used to evaluate the geometric properties of storms in the City of Los Angeles, CA. The database includes selected months containing significant rainfall during the period 1996-2007. For each time step, areas of contiguous rainfall were identified as individual storm cells. An idealized ellipse was fit to each storm cell and the properties of the ellipse (e.g., size, shape, orientation, velocity and other parameters) were recorded. To accurately account for the range of storm cell sizes, capture a large number of storm cells in a climatologically similar area, assess the variability of storm movement, and minimize the impact of edge effects (i.e., incomplete coverage of cells entering and leaving), a study area substantially larger than the City of Los Angeles was used. The study area extends from city center to 30 miles north to the crest of San Gabriel Mountains, 45 miles east to Ontario, 60 miles south to Santa Catalina Island, and 70 miles west to Oxnard, an area of about10,000 square miles. Radar data for this area over 30 months in the study yields many thousands of storm cells for analysis. Storms were separated into classes by origin, direction and speed of movement. Preliminary investigations considers three types: Arctic origin (west-northwest), Pacific origin (southwest) and Tropical origin (south or stationary). Radar data (for 1996-2007) and upper air maps (1948-2006) are used to identify the direction and speed of significant precipitation events. Typical duration and temporal patterns of Los Angeles historical storms were described by season and storm type. Time of maximum intensity loading variation were determined for a selection of historic storms Depth-Areal Reduction Factors (DARF) for cloudbursts were developedfrom the radar data. These data curves are fit to equations showing the relationships between DARF, area and central intensity. Separate DARF curves are developed for 6X (6 events per year), 4X, 3X, 2X, 1, 2, 5 and 10 year recurrence, and durations from 5 minutes to 7-days. A comparison is made between DARF derived in these analyses with NOAA Atlas 12 DARF, the USACE Sierra Madre Storm and other DARF developed for the interior Southwest. Orographic increases in DDF are related to the Los Angeles County Flood Control District Hydrology Manual 24-hr 50-yr Precipitation maps, elevation from USGS topographic maps and Mean Annual Precipitation maps.

Equations for estimating synthetic unit-hydrograph parameter values for small watersheds in Lake County, Illinois

USGS Publications Warehouse

Melching, C.S.; Marquardt, J.S.

1997-01-01

Design hydrographs computed from design storms, simple models of abstractions (interception, depression storage, and infiltration), and synthetic unit hydrographs provide vital information for stormwater, flood-plain, and water-resources management throughout the United States. Rainfall and runoff data for small watersheds in Lake County collected between 1990 and 1995 were studied to develop equations for estimation of synthetic unit-hydrograph parameters on the basis of watershed and storm characteristics. The synthetic unit-hydrograph parameters of interest were the time of concentration (TC) and watershed-storage coefficient (R) for the Clark unit-hydrograph method, the unit-graph lag (UL) for the Soil Conservation Service (now known as the Natural Resources Conservation Service) dimensionless unit hydrograph, and the hydrograph-time lag (TL) for the linear-reservoir method for unit-hydrograph estimation. Data from 66 storms with effective-precipitation depths greater than 0.4 inches on 9 small watersheds (areas between 0.06 and 37 square miles (mi2)) were utilized to develop the estimation equations, and data from 11 storms on 8 of these watersheds were utilized to verify (test) the estimation equations. The synthetic unit-hydrograph parameters were determined by calibration using the U.S. Army Corps of Engineers Flood Hydrograph Package HEC-1 (TC, R, and UL) or by manual analysis of the rainfall and run-off data (TL). The relation between synthetic unit-hydrograph parameters, and watershed and storm characteristics was determined by multiple linear regression of the logarithms of the parameters and characteristics. Separate sets of equations were developed with watershed area and main channel length as the starting parameters. Percentage of impervious cover, main channel slope, and depth of effective precipitation also were identified as important characteristics for estimation of synthetic unit-hydrograph parameters. The estimation equations utilizing area had multiple correlation coefficients of 0.873, 0.961, 0.968, and 0.963 for TC, R, UL, and TL, respectively, and the estimation equations utilizing main channel length had multiple correlation coefficients of 0.845, 0.957, 0.961, and 0.963 for TC, R, UL, and TL, respectively. Simulation of the measured hydrographs for the verification storms utilizing TC and R obtained from the estimation equations yielded good results without calibration. The peak discharge for 8 of the 11 storms was estimated within 25 percent and the time-to-peak discharge for 10 of the 11 storms was estimated within 20 percent. Thus, application of the estimation equations to determine synthetic unit-hydrograph parameters for design-storm simulation may result in reliable design hydrographs; as long as the physical characteristics of the watersheds under consideration are within the range of those for the watersheds in this study (area: 0.06-37 mi2, main channel length: 0.33-16.6 miles, main channel slope: 3.13-55.3 feet per mile, and percentage of impervious cover: 7.32-40.6 percent). The estimation equations are most reliable when applied to watersheds with areas less than 25 mi2.

A stability analysis of AVE-4 severe weather soundings

NASA Technical Reports Server (NTRS)

Johnson, D. L.

1982-01-01

The stability and vertical structure of an average severe storm sounding, consisting of both thermodynamic and wind vertical profiles, were investigated to determine if they could be distinguished from an average lag sounding taken 3 to 6 hours prior to severe weather occurrence. The term average is defined here to indicate the arithmetic mean of a parameter, as a function of altitude, determined from a large number of available observations taken either close to severe weather occurrence, or else more than 3 hours before it occurs. The investigative computations were also done to help determine if a severe storm forecast or index could possibly be used or developed. These mean vertical profiles of thermodynamic and wind parameters as a function of severity of the weather, determined from manually digitized radar (MDR) categories are presented. Profile differences and stability index differences are presented along with the development of the Johnson Lag Index (JLI) which is determined entirely upon environmental vertical parameter differences between conditions 3 hours prior to severe weather, and severe weather itself.

Understanding impacts of tropical storms and hurricanes on submerged bank reefs and coral communities in the northwestern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Lugo-Fernández, A.; Gravois, M.

2010-06-01

A 100-year climatology of tropical storms and hurricanes within a 200-km buffer was developed to study their impacts on coral reefs of the Flower Garden Banks (FGB) and neighboring banks of the northwestern Gulf of Mexico. The FGB are most commonly affected by tropical storms from May through November, peaking in August-September. Storms approach from all directions; however, the majority of them approach from the southeast and southwest, which suggests a correlation with storm origin in the Atlantic and Gulf of Mexico. A storm activity cycle lasting 30-40 years was identified similar to that known in the Atlantic basin, and is similar to the recovery time for impacted reefs. On average there is 52% chance of a storm approaching within 200 km of the FGB every year, but only 17% chance of a direct hit every year. Storm-generated waves 5-25 m in height and periods of 11-15 s induce particle speeds of 1-4 m s -1 near these reefs. The wave-current flow is capable of transporting large (˜3 cm) sediment particles, uplifting the near-bottom nepheloid layer to the banks tops, but not enough to break coral skeletons. The resulting storm-driven turbulence induces cooling by heat extraction, mixing, and upwelling, which reduces coral bleaching potential and deepens the mixed layer by about 20 m. Tropical storms also aid larvae dispersal from and onto the FGB. Low storm activity in 1994-2004 contributed to an 18% coral cover increase, but Hurricane Rita in 2005 reduced it by 11% and brought coral cover to nearly pre-1994 levels. These results suggest that the FGB reefs and neighboring reef banks act as coral refugia because of their offshore location and deep position in the water column, which shields them from deleterious effects of all but the strongest hurricanes.

An automated and integrated framework for dust storm detection based on ogc web processing services

NASA Astrophysics Data System (ADS)

Xiao, F.; Shea, G. Y. K.; Wong, M. S.; Campbell, J.

2014-11-01

Dust storms are known to have adverse effects on public health. Atmospheric dust loading is also one of the major uncertainties in global climatic modelling as it is known to have a significant impact on the radiation budget and atmospheric stability. The complexity of building scientific dust storm models is coupled with the scientific computation advancement, ongoing computing platform development, and the development of heterogeneous Earth Observation (EO) networks. It is a challenging task to develop an integrated and automated scheme for dust storm detection that combines Geo-Processing frameworks, scientific models and EO data together to enable the dust storm detection and tracking processes in a dynamic and timely manner. This study develops an automated and integrated framework for dust storm detection and tracking based on the Web Processing Services (WPS) initiated by Open Geospatial Consortium (OGC). The presented WPS framework consists of EO data retrieval components, dust storm detecting and tracking component, and service chain orchestration engine. The EO data processing component is implemented based on OPeNDAP standard. The dust storm detecting and tracking component combines three earth scientific models, which are SBDART model (for computing aerosol optical depth (AOT) of dust particles), WRF model (for simulating meteorological parameters) and HYSPLIT model (for simulating the dust storm transport processes). The service chain orchestration engine is implemented based on Business Process Execution Language for Web Service (BPEL4WS) using open-source software. The output results, including horizontal and vertical AOT distribution of dust particles as well as their transport paths, were represented using KML/XML and displayed in Google Earth. A serious dust storm, which occurred over East Asia from 26 to 28 Apr 2012, is used to test the applicability of the proposed WPS framework. Our aim here is to solve a specific instance of a complex EO data and scientific model integration problem by using a framework and scientific workflow approach together. The experimental result shows that this newly automated and integrated framework can be used to give advance near real-time warning of dust storms, for both environmental authorities and public. The methods presented in this paper might be also generalized to other types of Earth system models, leading to improved ease of use and flexibility.

Nitrate Removal Rates in Denitrifying Bioreactors During Storm Flows

NASA Astrophysics Data System (ADS)

Pluer, W.; Walter, T.

2017-12-01

Field denitrifying bioreactors are designed to reduce excess nitrate (NO3-) pollution in runoff from agricultural fields. Field bioreactors saturate organic matter to create conditions that facilitate microbial denitrification. Prior studies using steady flow in lab-scale bioreactors showed that a hydraulic retention time (HRT) between 4 and 10 hours was optimal for reducing NO3- loads. However, during storm-induced events, flow rate and actual HRT fluctuate. These fluctuations have the potential to disrupt the system in significant ways that are not captured by the idealized steady-flow HRT models. The goal of this study was to investigate removal rate during dynamic storm flows of variable rates and durations. Our results indicate that storm peak flow and duration were not significant controlling variables. Instead, we found high correlations (p=0.004) in average removal rates between bioreactors displaying a predominantly uniform flow pattern compared with bioreactors that exhibited preferential flow (24.4 and 21.4 g N m-3 d-1, respectively). This suggests that the internal flow patterns are a more significant driver of removal rate than external factors of the storm hydrograph. Designing for flow patterns in addition to theoretical HRT will facilitate complete mixing within the bioreactors. This will help maximize excess NO3- removal during large storm-induced runoff events.

Levee Scour Protection for Storm Waves

NASA Astrophysics Data System (ADS)

Johnson, E.; Sustainable; Resiliency in Levee Scour Protection

2011-12-01

Earnest Johnson, Firat Y. Testik *, Nadarajah Ravichandran Civil Engineering, Clemson University, Clemson, SC, USA * Contact author ftestik@clemson.edu Levee failure due to scouring has been a prominent occurrence among intense storm surges and waves, giving rise to the implementation of various scour protection measures over the years. This study is to investigate the levee scour and to compare different scour protection measures on a model-levee system in a laboratory wave tank. The protection measures that are tested and compared for their effectiveness in this study include turf reinforcement mats, woven geotextiles, and core-locs. This is an ongoing research effort and experiments are currently being conducted with model levees constructed based upon the United States Army Corps of Engineers' levee design and construction guidelines under various simulated storm conditions. Parameters such as wave elevations, deformation time history of the floodwall, and the scour depth are measured in each test. The finding of this research will be translated to provide effective scour protection measures for robust levee designs.

Technique for assessing vegetation-induced moisture flux, with implications for global climate modeling

NASA Technical Reports Server (NTRS)

Macari, Emir Jose

1990-01-01

The time between storms, the duration of storms, and the storm depths are studied in relation to vegetation controls on the disposition of rainfall. It is proposed that understanding the movement of water between the vegetation and soil (including evapotranspiration and infiltration) will be the gateway for modeling atmospheric flux and improving global climate models. The overall objective goal of the proposed research effort is to develop a field/lab methodology which will provide a better understanding of vegetation induced water movement. Water flow initiated from stem flow of wooded slopes feeds soil water pathways, which in turn feed the deeper ground water system and give rise to stream response. This is balanced by more water inputs via throughfall, where it percolates the soil matrix and allows much greater rates of evapotranspiration and atmospheric/soil moisture flux. This research study seeks to gain an understanding of the effect of vegetation on soil moisture, and the effect of this differential wetting on resulting evapotranspiration and atmospheric flux.

Scaling relationships between bed load volumes, transport distances, and stream power in steep mountain channels

NASA Astrophysics Data System (ADS)

Schneider, Johannes M.; Turowski, Jens M.; Rickenmann, Dieter; Hegglin, Ramon; Arrigo, Sabrina; Mao, Luca; Kirchner, James W.

2014-03-01

Bed load transport during storm events is both an agent of geomorphic change and a significant natural hazard in mountain regions. Thus, predicting bed load transport is a central challenge in fluvial geomorphology and natural hazard risk assessment. Bed load transport during storm events depends on the width and depth of bed scour, as well as the transport distances of individual sediment grains. We traced individual gravels in two steep mountain streams, the Erlenbach (Switzerland) and Rio Cordon (Italy), using magnetic and radio frequency identification tags, and measured their bed load transport rates using calibrated geophone bed load sensors in the Erlenbach and a bed load trap in the Rio Cordon. Tracer transport distances and bed load volumes exhibited approximate power law scaling with both the peak stream power and the cumulative stream energy of individual hydrologic events. Bed load volumes scaled much more steeply with peak stream power and cumulative stream energy than tracer transport distances did, and bed load volumes scaled as roughly the third power of transport distances. These observations imply that large bed load transport events become large primarily by scouring the bed deeper and wider, and only secondarily by transporting the mobilized sediment farther. Using the sediment continuity equation, we can estimate the mean effective thickness of the actively transported layer, averaged over the entire channel width and the duration of individual flow events. This active layer thickness also followed approximate power law scaling with peak stream power and cumulative stream energy and ranged up to 0.57 m in the Erlenbach, broadly consistent with independent measurements.

Arctic Moisture Source for Eurasian Snow Cover Variations in Autumn

NASA Astrophysics Data System (ADS)

Wegmann, M.

2015-12-01

Global warming is enhanced at high northern latitudes where the Arctic surface airtemperature has risen at twice the rate of the global average in recent decades - afeature called Arctic amplification. This recent Arctic warming signal likely resultsfrom several factors such as the albedo feedback due to a diminishing cryosphere,enhanced poleward atmospheric and oceanic transport, and change in humidity. Moreover, Arcticsummer sea-ice extent has declined by more than 10% per decade since the start ofthe satellite era (e.g. Stroeve et al., 2012), culminating in a new record low inSeptember 2012.Eurasian snow cover changes have been suggested as a driver for changes in theArctic Oscillation and might provide a link between sea ice decline in the Arcticduring summer and atmospheric circulation in the following winter. However, themechanism connecting snow cover in Eurasia to sea ice decline in autumn is stillunder debate. Our analysis focuses on sea ice decline in the Barents-Kara Sea region, which allowsus to specify regions of interest for FLEXPART forward and backwards moisturetrajectories. Based on Eularian and Lagrangian diagnostics from ERA-INTERIM, wecan address the origin and cause of late autumn snow depth variations in a dense(snow observations from 820 land stations), unutilized observational datasets over theCommonwealth of Independent States.Open waters in the Barents and Kara Sea have been shown to increase the diabaticheating of the atmosphere, which amplifies baroclinic cyclones and might induce aremote atmospheric response by triggering stationary Rossby waves (Honda et al.2009).In agreement with these studies, our results show enhanced storm activity originatingat the Barents and Kara with disturbances entering the continent through a smallsector from the Barents and Kara Seas. Maxima in storm activity trigger increasing uplift, oftenaccompanied by positive snowfall and snow depth anomalies.We show that declining sea ice in the Barents and Kara Seas acts as moisture sourcefor enhanced Siberian snow cover as a result of changed tropospheric moisturetransport. Transient disturbances enter the continent from the Barents and Kara Seasregion, related to anomalies in the planetary wave pattern and move southward alongthe Ural mountains.

Atmospheric inputs of organic matter to a forested watershed: Variations from storm to storm over the seasons

USGS Publications Warehouse

Iavorivska , Lidiia; Boyer, Elizabeth W.; Miller, Matthew P.; Brown, Michael G.; Vasilopoulos , Terrie; Fuentes, Jose D.; Duffy, Christopher J.

2016-01-01

The objectives of this study were to determine the quantity and chemical composition of precipitation inputs of dissolved organic carbon (DOC) to a forested watershed; and to characterize the associated temporal variability. We sampled most precipitation that occurred from May 2012 through August 2013 at the Susquehanna Shale Hills Critical Zone Observatory (Pennsylvania, USA). Sub-event precipitation samples (159) were collected sequentially during 90 events; covering various types of synoptic meteorological conditions in all climatic seasons. Precipitation DOC concentrations and rates of wet atmospheric DOC deposition were highly variable from storm to storm, ranging from 0.3 to 5.6 mg C L−1 and from 0.5 to 32.8 mg C m−2 h−1, respectively. Seasonally, storms in spring and summer had higher concentrations of DOC and more optically active organic matter than in winter. Higher DOC concentrations resulted from weather types that favor air advection, where cold frontal systems, on average, delivered more than warm/stationary fronts and northeasters. A mixed modeling statistical approach revealed that factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in dissolved organic matter that can be useful in modeling of atmospheric oxidative chemistry, exploring relationships between organics and other elements of precipitation chemistry, and in considering temporal changes in ecosystem nutrient balances and microbial activity.

An investigation of recent storm histories using Ground Penetrating Radar at Bay-Bay Spit, Bicol, Central Philippines

NASA Astrophysics Data System (ADS)

Switzer, Adam D.; Pile, Jeremy; Soria, Janneli Lea A.; Siringan, Fernando; Daag, Arturo; Brill, Dominik

2016-04-01

The Philippine archipelago lies in the path of seasonal tropical cyclones, and much of the coast is prone to periodic inundation and overwash during storm surges. On example is typhoon Durian a category 3 storm that made landfall on the 30th November 2006, in Bicol province, on the east central Philippine coast. Satellite imagery from May 2007 reveal that Durian breached a sandy spit that runs southeast from the mouth of the Quinale River at Bay-Bay village towards Tabaco City. The imagery also showed that, although the breach site showed signs of partial recovery, geomorphological evidence of the inundation event associated with typhoon Durian still remains. In 2012 we mapped the geomorphological features of Durian. In June 2013 we returned to conduct Ground Penetrating Radar (GPR) surveys on the Bay-Bay spit to investigate potential subsurface evidence of previous storm events. The GPR surveys comprised five, 1.5 km, longshore profiles and 12 cross-shore profiles, of 50 m - 200 m in length. The GPR system used for this study was a Sensors and Software Noggin with 100 Mhz antennas. Near surface velocities were determine using Hyperbolae matching in order to estimate depth. Topographic and positional data were collected using a dGPS system. After minimal processing depth of penetration during the survey varied from 2 - 8 m. The cross-shore GPR profiles reveal at least two erosional events prior to 2006 typhoon Durian, with approximately 10 m of recovery and progradation between each erosion surface. The GPR profiles that captured the erosional features were revisited in September 2013 for trial pitting, stratigraphic description, and sediment sampling. Sediment cores were taken horizontally from the trench walls and vertically from the trench bases to date sediments using Optically Stimulated Luminescence (OSL), which eventually could constrain the timing of the erosional surfaces.

Impact of heliogeophysical disturbances on ionospheric HF channels

NASA Astrophysics Data System (ADS)

Uryadov, V. P.; Vybornov, F. I.; Kolchev, A. A.; Vertogradov, G. G.; Sklyarevsky, M. S.; Egoshin, I. A.; Shumaev, V. V.; Chernov, A. G.

2018-04-01

The article presents the results of the observation of a strong magnetic storm and two X-ray flares during the summer solstice in 2015, and their impact on the HF signals characteristics in ionospheric oblique sounding. It was found that the negative phase of the magnetic storm led to a strong degradation of the ionospheric channel, ultimately causing a long blackout on paths adjacent to subauroral latitudes. On mid-latitude paths, the decrease in 1FMOF reached ∼50% relative to the average values for the quiet ionosphere. It is shown that the propagation conditions via the sporadic Es layer during the magnetic storm on a subauroral path are substantially better than those for F-mode propagation via the upper ionosphere. The delay of the sharp decrease in 1FMOF during the main phase of the magnetic storm allowed us to determine the propagation velocity of the negative phase disturbances (∼100 m/s) from subauroral to mid-latitude ionosphere along two paths: Lovozero - Yoshkar-Ola and Cyprus - Nizhny Novgorod. It is shown that both the LOF and the signal/noise ratio averaged over the frequency band corresponding to the propagation mode via the sporadic Es layer correlate well with the auroral AE index. Using an over-the-horizon chirp radar with a bistatic configuration on the Cyprus - Rostov-on-Don path, we located small-scale scattering irregularities responsible for abnormal signals in the region of the equatorial boundary of the auroral oval.

Multi-decadal and seasonal variability of dust observations in West Greenland.

NASA Astrophysics Data System (ADS)

Bullard, Joanna E.; Mockford, Tom

2017-04-01

Since the early 1900s expedition records from west Greenland have reported local dust storms. The Kangerlussuaq region, near the inland ice, is dry (mean annual precipitation <160 mm) with, on average, 150 snow-free days per year. The main local dust sources are active, proglacial outwash plains although reworking of loess deposits may also be important. This paper presents an analysis of 70-years of dust storm observations (1945-2015) based on WMO weather codes 6 (dust haze), 7 (raised dust or sand) and 9 (distant or past dust storm) and associated wind data. The 70-year average number of dust observations days is 5 per year but variable ranging from 0 observations to 23 observations in 1985. Over the past 7 decades the number of dust days has increased from <30 in 1945-54 to >75 in 1995-2004 and 2005-2015. The seasonality of dust observations has remained consistent throughout most of the period. Dust days occur all year round but are most frequent in May-June and September-October and are associated with minimum snow cover and glacial meltwater-driven sediment supply to the outwash plains during spring and fall flood events. Wind regime is bimodal dominated by katabatic winds from the northeast, which are strongest and most frequent during winter months (Nov-Jan), with less frequent, southwesterly winds generated by Atlantic storms mostly confined to spring (May, June). The southwesterly winds are those most likely to transport dust onto the Greenland ice sheet.

Percentage entrainment of constituent loads in urban runoff, south Florida

USGS Publications Warehouse

Miller, R.A.

1985-01-01

Runoff quantity and quality data from four urban basins in south Florida were analyzed to determine the entrainment of total nitrogen, total phosphorus, total carbon, chemical oxygen demand, suspended solids, and total lead within the stormwater runoff. Land use of the homogeneously developed basins are residential (single family), highway, commercial, and apartment (multifamily). A computational procedure was used to calculate, for all storms that had water-quality data, the percentage of constituent load entrainment in specified depths of runoff. The plot of percentage of constituent load entrained as a function of runoff is termed the percentage-entrainment curve. Percentage-entrainment curves were developed for three different source areas of basin runoff: (1) the hydraulically effective impervious area, (2) the contributing area, and (3) the drainage area. With basin runoff expressed in inches over the contributing area, the depth of runoff required to remove 90 percent of the constituent load ranged from about 0.4 inch to about 1.4 inches; and to remove 80 percent, from about 0.3 to 0.9 inch. Analysis of variance, using depth of runoff from the contributing area as the response variable, showed that the factor 'basin' is statistically significant, but that the factor 'constituent' is not statistically significant in the forming of the percentage-entrainment curve. Evidently the sewerage design, whether elongated or concise in plan dictates the shape of the percentage-entrainment curve. The percentage-entrainment curves for all constituents were averaged for each basin and plotted against basin runoff for three source areas of runoff-the hydraulically effective impervious area, the contributing area, and the drainage area. The relative positions of the three curves are directly related to the relative sizes of the three source areas considered. One general percentage-entrainment curve based on runoff from the contributing area was formed by averaging across both constituents and basins. Its coordinates are: 0.25 inch of runoff for 50-percent entrainment, 0.65 inch of runoff for 80-percent entrainment, and 0.95 inch of runoff for 90-percent entrainment. The general percentage-entrainment curve based on runoff from the hydraulically effective impervious area has runoff values of 0.35, 0.95, 1.6 inches, respectively.

Assessment of the Great Lakes Marine Renewable Energy Resources: Characterizing Lake Erie Surge, Seiche and Waves

NASA Astrophysics Data System (ADS)

Farhadzadeh, A.; Hashemi, M. R.

2016-02-01

Lake Erie, the fourth largest in surface area, smallest in volume and shallowest among the Great Lakes is approximately 400 km long and 90 km wide. Short term lake level variations are due to storm surge generated by high winds and moving pressure systems over the lake mainly in the southwest-northeast direction, along the lakes longitudinal axis. The historical wave data from three active offshore buoys shows that significant wave height can exceed 5 m in the eastern and central basins. The long-term lake level data show that storm surge can reach up to 3 m in eastern Lake Erie. Owing its shallow depth, Lake Erie frequently experiences seiching motions, the low frequency oscillations that are initiated by storm surge. The seiches whose first mode of oscillations has a period of nearly 14.2 hours can last from several hours to days. In this study, the Lake Erie potential for power generation, primarily using storm surge and seiche and also waves are assessed. Given the cyclic lake level variations due to storm-induced seiching, a concept similar to that of tidal range development is utilized to assess the potential of storm surge and seiche energy harvesting mechanisms for power generation. In addition, wave energy resources of the Lake is characterized -. To achieve these objectives, the following steps are taken : (1) Frequency of occurrence for extreme storm surge and wave events is determined using extreme value analysis such as Peak-Over-Threshold method for the long-term water level and wave data; (2) Spatial and temporal variations of wave height, storm surge and seiche are characterized. The characterization is carried out using the wave and storm surge outputs from numerical simulation of a number of historical extreme events. The coupled ADCIRC and SWAN model is utilized for the modeling; (3) Assessment of the potentials for marine renewable power generation in Lake Erie is made. The approach can be extended to the other lakes in the Great Lakes region.

Atlas of depth-duration frequency of precipitation annual maxima for Texas

USGS Publications Warehouse

Asquith, William H.; Roussel, Meghan C.

2004-01-01

Ninety-six maps depicting the spatial variation of the depth-duration frequency of precipitation annual maxima for Texas are presented. The recurrence intervals represented are 2, 5, 10, 25, 50, 100, 250, and 500 years. The storm durations represented are 15 and 30 minutes; 1, 2, 3, 6, and 12 hours; and 1, 2, 3, 5, and 7 days. The maps were derived using geographically referenced parameter maps of probability distributions used in previously published research by the U.S. Geological Survey to model the magnitude and frequency of precipitation annual maxima for Texas. The maps in this report apply that research and update depth-duration frequency of precipitation maps available in earlier studies done by the National Weather Service.

An Extensive Study on Dynamical aspects of Dust Storm over the United Arab Emirates during 18-20 March 2012

NASA Astrophysics Data System (ADS)

Basha, Ghouse; Phanikumar, Devulapalli V.; Ouarda, Taha B. M. J.

2015-04-01

On 18 March 2012, a super dust storm event occurred over Middle East (ME) and lasted for several hours. Following to this, another dust storm occurred on early morning of 20 March 2012 with almost higher intensity. Both these storms reduced the horizontal visibility to few hundreds of meters and represented as one of the most intense and long duration dust storms over United Arab Emirates (UAE) in recent times. These storms also reduced the air quality in most parts of the ME implying the shutdown of Airports, schools and hundreds of people were hospitalized with respirational problems. In the context of the above, we have made a detailed study on the dynamical processes leading to triggering of dust storm over UAE and neighboring regions. We have also analyzed its impact on surface, and vertical profiles of background parameters and aerosols during the dust storm period by using ground-based, space borne, dust forecasting model, and reanalysis data sets. The synoptic and dynamic conditions responsible for the occurrence of the dust storm are discussed extensively by using European Centre for Medium-Range Weather Forecasts (ECMWF) ERA interim reanalysis data sets. The Impact of dust storm on surface and upper air radiosonde measurements and aerosol optical properties are also investigated before, during and after the dust storm event. During the dust storm, surface temperature decreased by 15oC when compared to before and after the event. PM10 values significantly increased maximum of about 1600µg/m3. Spatial variation of Aerosol Optical Depth (AOD) from Moderate-resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI) aerosol index (AI) exhibited very high values during the event and source region can be identified of dust transport to our region with this figure. The total attenuated backscatter at 550nm from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite shows the vertical extent of dust up to 8km. The dynamics of this event is related to coupling of subtropical jet and polar jet over the Saudi Arabia region, which leads to massive dust storm generation and dust transport through Rub-Al-Khali, and Persian Gulf over the UAE region. AOD from ground based measurements showed fourfold increase from 0.2 to 1.8 during the event implying an atmospheric forcing of ~ 150 Wm-2. In addition, vertical profile of heating rate showed heating of ~1.5 K/day at 3-4 km during the event. In the view of the above, the present event is discussed in the light of current understanding of dust storm aerosol optical and physical processes and associated dynamics over UAE region.

Automated Identification of Initial Storm Electrification and End-of-Storm Electrification Using Electric Field Mill Sensors

NASA Technical Reports Server (NTRS)

Maier, Launa M.; Huddleston, Lisa L.

2017-01-01

Kennedy Space Center (KSC) operations are located in a region which experiences one of the highest lightning densities across the United States. As a result, on average, KSC loses almost 30 minutes of operational availability each day for lightning sensitive activities. KSC is investigating using existing instrumentation and automated algorithms to improve the timeliness and accuracy of lightning warnings. Additionally, the automation routines will be warning on a grid to minimize under-warnings associated with not being located in the center of the warning area and over-warnings associated with encompassing too large an area. This study discusses utilization of electric field mill data to provide improved warning times. Specifically, this paper will demonstrate improved performance of an enveloping algorithm of the electric field mill data as compared with the electric field zero crossing to identify initial storm electrification. End-of-Storm-Oscillation (EOSO) identification algorithms will also be analyzed to identify performance improvement, if any, when compared with 30 minutes after the last lightning flash.

Water-quality assessment of stormwater runoff from a heavily used urban highway bridge in Miami, Florida

USGS Publications Warehouse

McKenzie, Donald J.; Irwin, G.A.

1983-01-01

Runoff from a heavily-traveled, 1.43-acre bridge section of Interstate-95 in Miami, Florida, was comprehensively monitored for both quality and quantity during five selected storms between November 1979 and May 1981. For most water-quality parameters, 6 to 11 samples were collected during each of the 5 runoff events. Concentrations of most parameters in the runoff were quite variable both during individual storm events and among the five storm events; however, the ranges in parameter concentration were about the same magnitude report for numerous other highway and urban drainages. Data were normalized to estimate the average, discharge-weighted parameter loads per storm per acre of bridge surface and results suggested that the most significant factor influencing stormwater loads was parameter concentration. Rainfall intensity and runoff volume, however, influenced rates of loading. The total number of antecedent dry days and traffic volume did not appear to be conspicously related to either runoff concentrations or loads. (USGS)

Electric field soundings through thunderstorms

NASA Technical Reports Server (NTRS)

Marshall, Thomas C.; Rust, W. D.

1991-01-01

Twelve balloon soundings of the electric field in thunderstorms are reported. The maximum magnitude of E in the storms averaged 96 +/-28 kV/m, with the largest being 146 kV/m. The maximum was usually observed between vertically adjacent regions of opposite charge. Using a 1D approximation to Gauss' law, four to ten charge regions in the storms are inferred. The magnitude of the density in the charge regions varied between 0.2 and 13 nC/cu m. The vertical extent of the charge regions ranged from 130 to 2100 m. None of the present 12 storms had charge distributions that fit the long-accepted model of Simpson et al. (1937, 1941) of a lower positive charge, a main negative charge, and an upper positive charge. In addition to regions similar to the Simpson model, the present storms had screening layers at the upper and lower cloud boundaries and extra charge regions, usually in the lower part of the cloud.

Coastal Hazard due to Tropical Cyclones in Mexico

NASA Astrophysics Data System (ADS)

Silva-Casarin, R.; Mendoza-Baldwin, E.; Marino-Tapia, I.; Enriquez, C.; Ruiz, G.; Escalante-MAncera, E.; Ruíz-Rentería, F.

2013-05-01

The Mexican coast is hit every year by at least 3 cyclones and it is affected for nearly 59 hours a year on average; this induces undesirable consequences, such as coastal erosion and flooding. To evaluate the hazard to which the coastal zone is exposes, a historical characterization of atmospheric conditions (surface winds and pressure conditions of the storms), waves (wave heights and their associated wave periods) and flooding levels due to tropical storms for more than 60 years is presented. The atmospheric and wave conditions were evaluated using a modification of the original parametric Hydromet-Rankin Vortex Model by Bretschneider (1990) and Holland (1980) as presented by Silva, et al. (2002). The flooding levels caused by hurricanes were estimated using a two-dimensional, vertically averaged finite volume model to evaluate the storm surge, Posada et al. (2008). The cyclone model was compared to the data series of 29 cyclones recorded by buoys of the National Data Buoy Center-NOAA and some data recorded in shallow waters near Cancun, Mexico and the flooding model was compared with observed data from Cancun, Mexico; both models gave good results. For the extreme analyses of wind, wave heights and maximum flooding levels on the Mexican coasts, maps of the scale and location parameters used in the Weibull cumulative distribution function and numerical results for different return periods are provided. The historical occurrence of tropical storms is also revised as some studies indicate that the average intensity of tropical cyclones is increasing; no definite trends pointing to an increase in storm frequency or intensity were found. What was in fact found is that although there are more cyclones in the Pacific Ocean and these persist longer, the intensity of the cyclones in the Atlantic Ocean is greater affecting. In any case, the strong necessity of avoiding storm induced coastal damage (erosion and flooding) is reflected in numerous works, such as this one, which aim to better manage the coastal area and reduce its vulnerability to hurricanes. References Bretschneider, C.L., 1990. Tropical Cyclones. Handbook of Coastal and Ocean Engineering, Gulf Publishing Co., Vol. 1, 249-370. Holland, G.L., 1980. An analytical model of wind and pressure profiles in hurricanes. Monthly Weather Review, 108, 1212-1218. Posada, G., Silva, R. & de Brye, S. 2008. Three dimensional hydrodynamic model with multiquadtree meshes. American Journal of Environmental Sciences. 4(3): 209-222. Silva, R., Govaere, G., Salles, P., Bautista, G. & Díaz, G. 2002. Oceanographic vulnerability to hurricanes on the Mexican coast. International Conference on Coastal Engineering, pp. 39-51.

Influences of Hydrological Regime on Runoff Quality and Pollutant Loadings in Tropical Urban Areas

NASA Astrophysics Data System (ADS)

Chow, M.; Yusop, Z.

2011-12-01

Experience in many developed countries suggests that non point source (NPS) pollution is still the main contributor to pollutant loadings into water bodies in urban areas. However, the mechanism of NPS pollutant transport and the influences of hydrologic regime on the pollutant loading are still unclear. Understanding these interactions will be useful for improving design criteria and strategies for controlling NPS pollution in urban areas. This issue is also extremely relevant in tropical environment because its rainfall and the runoff generation processes are so different from the temperate regions where most of the studies on NPS pollutant have been carried out. In this regard, an intensive study to investigate the extent of this pollution was carried out in Skudai, Johor, Malaysia. Three small catchments, each represents commercial, residential and industrial land use were selected. Stormwater samples and flow rate data were collected at these catchments over 52 storm events from year 2008 to 2009. Samples were analyzed for ten water quality constituents including total suspended solids, 5-day biochemical oxygen demand, chemical oxygen demand, oil and grease, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, soluble phosphorus, total phosphorus and zinc. Quality of stormwater runoff is estimated using Event Mean Concentration (EMC) value. The storm characteristics analyzed included rainfall depth, rainfall duration, mean intensity, max 5 minutes intensity, antecedent dry day, runoff volume and peak flow. Correlation coefficients were determined between storm parameters and EMCs for the residential, commercial and industrial catchments. Except for the antecedent storm mean intensity and antecedent dry days, the other rainfall and runoff variables were negatively correlated with EMCs of most pollutants. This study reinforced the earlier findings on the importance of antecedent dry days for causing greater EMC values with exceptions for oil and grease, nitrate nitrogen, total phosphorus and zinc. There is no positive correlation between rainfall intensity and EMC of constituents in all the studied catchments. In contrast, the pollutant loadings are influenced primarily by the rainfall and runoff characteristics. Rainfall depth, mean intensity, max 5 minute intensity, runoff volume and peak flow were positively correlated with the loadings of most of the constituents. Antecedent storm mean intensity and antecedent dry days seemed to be less important for estimating the pollutant loadings. Such study should be further conducted for acquiring a long term monitoring data related to storm runoff quality during rainfall, in order to have a better understanding on NPS pollution in urban areas.

Assessing cost-effectiveness of specific LID practice designs in response to large storm events

NASA Astrophysics Data System (ADS)

Chui, Ting Fong May; Liu, Xin; Zhan, Wenting

2016-02-01

Low impact development (LID) practices have become more important in urban stormwater management worldwide. However, most research on design optimization focuses on relatively large scale, and there is very limited information or guideline regarding individual LID practice designs (i.e., optimal depth, width and length). The objective of this study is to identify the optimal design by assessing the hydrological performance and the cost-effectiveness of different designs of LID practices at a household or business scale, and to analyze the sensitivity of the hydrological performance and the cost of the optimal design to different model and design parameters. First, EPA SWMM, automatically controlled by MATLAB, is used to obtain the peak runoff of different designs of three specific LID practices (i.e., green roof, bioretention and porous pavement) under different design storms (i.e., 2 yr and 50 yr design storms of Hong Kong, China and Seattle, U.S.). Then, life cycle cost is estimated for the different designs, and the optimal design, defined as the design with the lowest cost and at least 20% peak runoff reduction, is identified. Finally, sensitivity of the optimal design to the different design parameters is examined. The optimal design of green roof tends to be larger in area but thinner, while the optimal designs of bioretention and porous pavement tend to be smaller in area. To handle larger storms, however, it is more effective to increase the green roof depth, and to increase the area of the bioretention and porous pavement. Porous pavement is the most cost-effective for peak flow reduction, followed by bioretention and then green roof. The cost-effectiveness, measured as the peak runoff reduction/thousand Dollars of LID practices in Hong Kong (e.g., 0.02 L/103 US s, 0.15 L/103 US s and 0.93 L/103 US s for green roof, bioretention and porous pavement for 2 yr storm) is lower than that in Seattle (e.g., 0.03 L/103 US s, 0.29 L/103 US s and 1.58 L/103 US s for green roof, bioretention and porous pavement for 2 yr storm). The optimal designs are influenced by the model and design parameters (i.e., initial saturation, hydraulic conductivity and berm height). However, it overall does not affect the main trends and key insights derived, and the results are therefore generic and relevant to the household/business-scale optimal design of LID practices worldwide.

77 FR 112 - Effluent Limitations Guidelines and Standards for the Construction and Development Point Source...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-03

... Precipitation on Performance of Passive Treatment D. Exemptions--Design Storm Depth vs. Intensity E. Use of... treatment in the diversion ditches and the forebay. The third type of system tested was the same design as... and sediment controls were designed and implemented to mimic pre-developed peak flow and runoff...

40 CFR 258.42 - Approval of site-specific flexibility requests in Indian country.

Code of Federal Regulations, 2012 CFR

2012-07-01

... VI. (2) The owner and/or operator may operate Phase VI as a bioreactor by recirculating leachate and... IVA by recirculating leachate and landfill gas condensate, and by adding storm water and groundwater... than a 30-cm depth of leachate on the liner. (5) The owner and/or operator shall submit reports to the...

40 CFR 258.42 - Approval of site-specific flexibility requests in Indian country.

Code of Federal Regulations, 2013 CFR

2013-07-01

... VI. (2) The owner and/or operator may operate Phase VI as a bioreactor by recirculating leachate and... IVA by recirculating leachate and landfill gas condensate, and by adding storm water and groundwater... than a 30-cm depth of leachate on the liner. (5) The owner and/or operator shall submit reports to the...

40 CFR 258.42 - Approval of site-specific flexibility requests in Indian country.

Code of Federal Regulations, 2014 CFR

2014-07-01

... VI. (2) The owner and/or operator may operate Phase VI as a bioreactor by recirculating leachate and... IVA by recirculating leachate and landfill gas condensate, and by adding storm water and groundwater... than a 30-cm depth of leachate on the liner. (5) The owner and/or operator shall submit reports to the...

77 FR 11086 - Revised Notice of Intent To Prepare a Draft Environmental Impact Statement for the Brunswick...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-24

... DEPARTMENT OF DEFENSE Department of the Army; Corps of Engineers Revised Notice of Intent To Prepare a Draft Environmental Impact Statement for the Brunswick County Beaches, NC, Coastal Storm Damage... the borrow area extend between 1-5 miles offshore and at depth contours between - 10 and -30 feet. 5...

Joint Probability Analysis of Extreme Precipitation and Storm Tide in a Coastal City under Changing Environment

PubMed Central

Xu, Kui; Ma, Chao; Lian, Jijian; Bin, Lingling

2014-01-01

Catastrophic flooding resulting from extreme meteorological events has occurred more frequently and drawn great attention in recent years in China. In coastal areas, extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. The impact of storm tide or changing environment on flooding is ignored or underestimated in the design of drainage systems of today in coastal areas in China. This paper investigates the joint probability of extreme precipitation and storm tide and its change using copula-based models in Fuzhou City. The change point at the year of 1984 detected by Mann-Kendall and Pettitt’s tests divides the extreme precipitation series into two subsequences. For each subsequence the probability of the joint behavior of extreme precipitation and storm tide is estimated by the optimal copula. Results show that the joint probability has increased by more than 300% on average after 1984 (α = 0.05). The design joint return period (RP) of extreme precipitation and storm tide is estimated to propose a design standard for future flooding preparedness. For a combination of extreme precipitation and storm tide, the design joint RP has become smaller than before. It implies that flooding would happen more often after 1984, which corresponds with the observation. The study would facilitate understanding the change of flood risk and proposing the adaption measures for coastal areas under a changing environment. PMID:25310006

Joint probability analysis of extreme precipitation and storm tide in a coastal city under changing environment.

PubMed

Xu, Kui; Ma, Chao; Lian, Jijian; Bin, Lingling

2014-01-01

Catastrophic flooding resulting from extreme meteorological events has occurred more frequently and drawn great attention in recent years in China. In coastal areas, extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. The impact of storm tide or changing environment on flooding is ignored or underestimated in the design of drainage systems of today in coastal areas in China. This paper investigates the joint probability of extreme precipitation and storm tide and its change using copula-based models in Fuzhou City. The change point at the year of 1984 detected by Mann-Kendall and Pettitt's tests divides the extreme precipitation series into two subsequences. For each subsequence the probability of the joint behavior of extreme precipitation and storm tide is estimated by the optimal copula. Results show that the joint probability has increased by more than 300% on average after 1984 (α = 0.05). The design joint return period (RP) of extreme precipitation and storm tide is estimated to propose a design standard for future flooding preparedness. For a combination of extreme precipitation and storm tide, the design joint RP has become smaller than before. It implies that flooding would happen more often after 1984, which corresponds with the observation. The study would facilitate understanding the change of flood risk and proposing the adaption measures for coastal areas under a changing environment.

The influence of neap-spring tidal variation and wave energy on sediment flux in salt marsh tidal creeks

USGS Publications Warehouse

Lacy, Jessica; Ferner, Matthew C.; Callaway, John C.

2018-01-01

Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three six-to-ten-week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally-averaged suspended-sediment flux (SSF) in the tidal creeks decreased with increasing tidal energy, and SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF measured during the deployments. During ebb tides following the highest tides, velocities exceeded 1 m/s in the narrow tidal creeks, resulting in negative tidally-averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally-averaged SSF was positive in wavey conditions with moderate tides. Spring-tide sediment export was about 50% less at a station 130 m further up the tidal creek than at the creek mouth. The negative tidally-averaged water flux near the creek mouth during spring tides indicates that in the lower marsh, some of the water flooding directly across the bay--marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well.

The Response of Mid-Latitude Ionospheric TEC to Geomagnetic Storms and Solar Flares

NASA Astrophysics Data System (ADS)

Huang, Z.; Roussel-Dupre, R.

2004-12-01

The effects of geomagnetic storms and solar flares on the ionosphere are manifested as large magnitude sudden fluctuations in the Total Electron Content (TEC). In this study, the broadband VHF signal (30-100MHz) data from the Los Alamos Portable Pulser (LAPP) received by the FORTE (Fast Onboard Recording of Transient Events) satellite during the period of 1997-2002 are used to investigate the mean TEC variation response to geomagnetic storm. A total of 14 geomagnetic storms are selected where FORTE-LAPP data are available to derive average TECs during extended storm-time and non-storm time for a given storm. The variations in the ionospheric TECs at Los Alamos, New Mexico are investigated for the 14 selected geomagnetic storms. In most cases (12 out of 14), we see overall enhancements in TEC as a result of geomagnetic storm impact at Los Alamos. The relative enhancements in TEC at Los Alamos due to a geomagnetic storm can reach as high as 3-fold of the normal TEC values. The overall absolute enhancements in TEC at Los Alamos are up to about 30 TECU. The magnitude of TEC enhancements is diversified over all storm categories without a clean-cut relationship between the storm intensity and the TEC enhancement. The mean TEC variation response to geomagnetic storm can be complicated when several consecutive storms occurred in a row and a net TEC reduction may be seen. Data of continuous GPS TEC measurements are collected at a 1-minute time resolution during July 2004 when 5 X-class solar flares occurred from two Allen Osborne Associates ICS-4000Z GPS receivers mounted at the Physics Building at Los Alamos National Laboratory. In detecting effects of solar flares on the ionospheric TEC, we apply appropriate filtering to remove the linear trend of TEC and a coherent processing of TEC variations simultaneously for all the visible GPS satellites in a given time interval. The responses of ionospheric TEC at minute time scale to these powerful impulsive solar flares are investigated. The onset time of the ionospheric response and the magnitude of the TEC fluctuations and its time derivative are examined along with their relationships with the solar flux characteristics, duration of the flare and location of the flare on the Sun, X-ray emission variations during the flares, and local time of the flare occurrence.

Seasonal Temperature Pattern Indicating Martian Dust Storms

NASA Image and Video Library

2016-06-09

This graphic shows Martian atmospheric temperature data related to seasonal patterns in occurrence of large regional dust storms. The data shown here were collected by the Mars Climate Sounder instrument on NASA's Mars Reconnaissance Orbiter over the course of one-half of a Martian year, during 2012 and 2013. The color coding indicates daytime temperatures of a layer of the atmosphere centered about 16 miles (25 kilometers) above ground level, corresponding to the color-key bar at the bottom of the graphic. Three regional dust storms indicated by increased temperatures are labeled A, B and C. A similar sequence of three large regional dust storms has been seen in atmosphere-temperature data from five other Martian years. The vertical axis is latitude on Mars, from the north pole at the top to south pole at the bottom. Each graphed data point is an average for all Martian longitudes around the planet. The horizontal axis is the time of year, spanning from the beginning of Mars' southern-hemisphere spring (on the left) to the end of southern-hemisphere summer. This is the half of the year when large Martian dust storms are most active. http://photojournal.jpl.nasa.gov/catalog/PIA20746

Increasing large scale windstorm damage in Western, Central and Northern European forests, 1951-2010

NASA Astrophysics Data System (ADS)

Gregow, H.; Laaksonen, A.; Alper, M. E.

2017-04-01

Using reports of forest losses caused directly by large scale windstorms (or primary damage, PD) from the European forest institute database (comprising 276 PD reports from 1951-2010), total growing stock (TGS) statistics of European forests and the daily North Atlantic Oscillation (NAO) index, we identify a statistically significant change in storm intensity in Western, Central and Northern Europe (17 countries). Using the validated set of storms, we found that the year 1990 represents a change-point at which the average intensity of the most destructive storms indicated by PD/TGS > 0.08% increased by more than a factor of three. A likelihood ratio test provides strong evidence that the change-point represents a real shift in the statistical behaviour of the time series. All but one of the seven catastrophic storms (PD/TGS > 0.2%) occurred since 1990. Additionally, we detected a related decrease in September-November PD/TGS and an increase in December-February PD/TGS. Our analyses point to the possibility that the impact of climate change on the North Atlantic storms hitting Europe has started during the last two and half decades.

Global mortality from storm surges is decreasing

NASA Astrophysics Data System (ADS)

Bouwer, Laurens M.; Jonkman, Sebastiaan N.

2018-01-01

Changes in society’s vulnerability to natural hazards are important to understand, as they determine current and future risks, and the need to improve protection. Very large impacts including high numbers of fatalities occur due to single storm surge flood events. Here, we report on impacts of global coastal storm surge events since the year 1900, based on a compilation of events and data on loss of life. We find that over the past, more than eight thousand people are killed and 1.5 million people are affected annually by storm surges. The occurrence of very substantial loss of life (>10 000 persons) from single events has however decreased over time. Moreover, there is a consistent decrease in event mortality, measured by the fraction of exposed people that are killed, for all global regions, except South East Asia. Average mortality for storm surges is slightly higher than for river floods, but lower than for flash floods. We also find that for the same coastal surge water level, mortality has decreased over time. This indicates that risk reduction efforts have been successful, but need to be continued with projected climate change, increased rates of sea-level rise and urbanisation in coastal zones.

Increasing large scale windstorm damage in Western, Central and Northern European forests, 1951–2010

PubMed Central

Gregow, H.; Laaksonen, A.; Alper, M. E.

2017-01-01

Using reports of forest losses caused directly by large scale windstorms (or primary damage, PD) from the European forest institute database (comprising 276 PD reports from 1951–2010), total growing stock (TGS) statistics of European forests and the daily North Atlantic Oscillation (NAO) index, we identify a statistically significant change in storm intensity in Western, Central and Northern Europe (17 countries). Using the validated set of storms, we found that the year 1990 represents a change-point at which the average intensity of the most destructive storms indicated by PD/TGS > 0.08% increased by more than a factor of three. A likelihood ratio test provides strong evidence that the change-point represents a real shift in the statistical behaviour of the time series. All but one of the seven catastrophic storms (PD/TGS > 0.2%) occurred since 1990. Additionally, we detected a related decrease in September–November PD/TGS and an increase in December–February PD/TGS. Our analyses point to the possibility that the impact of climate change on the North Atlantic storms hitting Europe has started during the last two and half decades. PMID:28401947

Tropical and Extratropical Cyclone Damages under Climate Change

NASA Astrophysics Data System (ADS)

Ranson, M.; Kousky, C.; Ruth, M.; Jantarasami, L.; Crimmins, A.; Tarquinio, L.

2014-12-01

This paper provides the first quantitative synthesis of the rapidly growing literature on future tropical and extratropical cyclone losses under climate change. We estimate a probability distribution for the predicted impact of changes in global surface air temperatures on future storm damages, using an ensemble of 296 estimates of the temperature-damage relationship from twenty studies. Our analysis produces three main empirical results. First, we find strong but not conclusive support for the hypothesis that climate change will cause damages from tropical cyclones and wind storms to increase, with most models (84 and 92 percent, respectively) predicting higher future storm damages due to climate change. Second, there is substantial variation in projected changes in losses across regions. Potential changes in damages are greatest in the North Atlantic basin, where the multi-model average predicts that a 2.5°C increase in global surface air temperature would cause hurricane damages to increase by 62 percent. The ensemble predictions for Western North Pacific tropical cyclones and European wind storms (extratropical cyclones) are approximately one third of that magnitude. Finally, our analysis shows that existing models of storm damages under climate change generate a wide range of predictions, ranging from moderate decreases to very large increases in losses.

Does it make sense to modify tropical cyclones? A decision-analytic assessment.

PubMed

Klima, Kelly; Morgan, M Granger; Grossmann, Iris; Emanuel, Kerry

2011-05-15

Recent dramatic increases in damages caused by tropical cyclones (TCs) and improved understanding of TC physics have led DHS to fund research on intentional hurricane modification. We present a decision analytic assessment of whether it is potentially cost-effective to attempt to lower the wind speed of TCs approaching South Florida by reducing sea surface temperatures with wind-wave pumps. Using historical data on hurricanes approaching South Florida, we develop prior probabilities of how storms might evolve. The effects of modification are estimated using a modern TC model. The FEMA HAZUS-MH MR3 damage model and census data on the value of property at risk are used to estimate expected economic losses. We compare wind damages after storm modification with damages after implementing hardening strategies protecting buildings. We find that if it were feasible and properly implemented, modification could reduce net losses from an intense storm more than hardening structures. However, hardening provides "fail safe" protection for average storms that might not be achieved if the only option were modification. The effect of natural variability is larger than that of either strategy. Damage from storm surge is modest in the scenario studied but might be abated by modification.

Modes of isolated, severe convective storm formation along the dryline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bluestein, H.B.; Parker, S.S.

1993-05-01

Patterns of the formation of isolated, severe convective storms along the dryline in the Southern plains of the United States during the spring over a 16-year period were determined from an examination of the evolution of radar echoes as depicted by WSR-57 microfilm data. It was found that in the first 30 min after the first echo, more than half of the radar echoes evolved into isolated storms as isolated cells from the start; others developed either from a pair of cells, from a line segment, from a cluster of cells, from the merger of mature cells, or from amore » squall line. Proximity soundings were constructed from both standard and special soundings, and from standard surface data. It was found that the estimated convective available potential energy and vertical shear are characteristic of the environment of supercell storms. The average time lag between the first echo and the first occurrence of severe weather of any type, or tornadoes alone, was approximately 2 h. There were no significant differences in the environmental parameters for the different modes of storm formation. 49 refs., 15 figs., 3 tabs.« less

A qualitative and quantitative assessment of the reproductive litter from Posidonia oceanica accumulated on a sand beach following a storm

NASA Astrophysics Data System (ADS)

Balestri, E.; Vallerini, F.; Lardicci, C.

2006-01-01

The biomass of reproductive litter from Posidonia oceanica deposited on a 3.5 km stretch of beach in the north-western Mediterranean, as a consequence of a storm in May 2004, was quantified. The damage caused by this storm to the meadow from which fruits originated was evaluated in terms of loss of seed production. Intermediate fruits (i.e., developing fruits) were the most important reproductive component, followed by immature and damaged fruits. No fully mature fruits were found. No significant differences in the average number of fruits and biomass accumulated were detected among beach sections hundreds of metres apart. Extrapolation of the results at four beach sections indicated that about 1 million fruits were deposited on the entire (3.5 km) beach. This was equivalent to the seed production potential of about 313,217 inflorescences, or a flowered area of 1500 m 2. The organic input to the beach was 224 kg ash-free dry weight (AFDM). These results suggest that storms may provide an unpredictable source of seed mortality in P. oceanica. The reproductive material produced by storms, however, may constitute an important source of allochthonous organic matter to the beach.

Solar wind driving of ionosphere-thermosphere responses during three storms on St. Patrick's Day.

NASA Astrophysics Data System (ADS)

Verkhoglyadova, O. P.; Tsurutani, B.; Mannucci, A. J.; Komjathy, A.; Mlynczak, M. G.; Hunt, L. A.; Paxton, L. J.

2015-12-01

We overview solar wind features of three intense CME-driven storms occurring around the same time in March of 2012, 2013 and 2015 (74 - 80 DOY). Differences in solar wind drivers lead to different ionosphere-thermosphere (IT) responses in time, magnitude, and to different pre-conditioning. The purpose of our study is to establish a correspondence between interplanetary transient structures (parts of a CME or a high-speed-stream) and dynamics of IT parameters over the course of a geomagnetic storm. Detailed analysis will be presented for the St. Patrick's Day storm of 2015. We introduce global metrics of daytime and dusktime average ionospheric response of VTEC estimates from over ~2000 GPS ground stations distributed globally. Nitric oxide and carbon dioxide cooling radiation fluxes measured by TIMED/SABER instrument are calculated in several latitudinal bins throughout the storm phases. In addition, GUVI observations of the dynamical response of the thermosphere (NO and O/N2) are compared. SSUSI observations of the equatorial ionosphere, particularly the magnitude and separation of the equatorial arcs are considered. In our analysis, metrics are inter-compared to get better understanding of the self-consistent IT response to solar wind driving.

Depth averaged wave-current interaction in the multi bank morphology of the southern North Sea

NASA Astrophysics Data System (ADS)

Komijani, Homayoon; Osuna, Pedro; Ocampo Torres, Francisco; Monbaliu, Jaak

2017-04-01

The effects of wind induced waves on the barotropic mean flow during a storm event in the southern North Sea are investigated. The well known radiation stress gradient theory of Longuet-Higgins and Stewart (1962, 1964) together with the influence of waves through the Stokes drift (Hasselmann, 1971 and Garret, 1976) are incorporated in the RANS equation system of the COHERENS circulation model (Luyten et al., 2005) following the methodology worked out by Bennis et al. (2011) . The SWAN spectral wave model (version 40.91, http://www.swan.tudelft.nl/) is used to provide the wave information. This allows us to take into account the dissipative terms of wave momentum flux to the mean flow such as depth induced wave breaking and bottom friction as well as the conservative terms of wave effects such as the vortex-force and wave induced pressure gradient. The resulting coupled COHERENS-SWAN model has been validated using the well known planar beach test case proposed by Haas and Warner (2009) in depth averaged mode. For the application in the southern North Sea, a series of nested grids using COHERENS (circulation model) and WAM cycle 4.5.3 (spectral wave model applied to the North Sea shelf area, Monbaliu et al. 2000; Günther, H. and A. Behrens, personal communications, May 2012) is set up to provide the hydrodynamic and wave boundary conditions for the COHERENS-SWAN two way coupled wave-current model for the Belgian coastal zone model. The improvements obtained in hindcasting the circulation processes in the Belgian coastal area during a storm event will be highlighted. But also difficulties faced in the coupling of the models and in the simulation of a real case storm will be discussed. In particular, some of the approaches for dealing with the numerical instabilities due to multi bank morphology of the southern North Sea will be addressed. References : Bennis, A.-C., F. Ardhuin, and F. Dumas (2011). "On the coupling of wave and three-dimensional circulation models: Choice of theoretical framework, practical implementation and adiabatic tests". In: Ocean modelling 40.3-4, 260-272.issn: 1463-5003.doi:{10.1016/j.ocemod.2011.09.003}. Garrett, C. (1976). "Generation of Langmuir circulations by surface waves-a feedback mechanism". In: J. Mar. Res.34.117-130. Haas, K.A. and J.C. Warner (2009). "Comparing a quasi-3D to a full 3D nearshore circulation model: SHORECIRC and ROMS". In: Ocean modelling26.1-2, 91-103.issn: 1463-5003.doi:{10.1016/j.ocemod.2008.09.003}. Hasselmann, K. (1971). "On the mass and momentum transfer between short gravity waves and larger-scale motions". In: Journal of Fluid Mechanics50.1, 189205.doi:10.1017/S0022112071002520. Longuet-Higgins, M.S. and R.W. Stewart (1962). "Radiation stress and mass transport in gravity waves, with application to surf beats". In: Journal of fluid mechanics 13.4, 481-504.issn: 0022-1120.doi:{10.1017/S0022112062000877}. Longuet-Higgins, M.S. and R.W. Stewart (1964). "Radiation stresses in water waves - a physical discussion, with applications". In:Deep-sea research 11.4, 529-562.doi:{10.1016/0011-7471(64)90001-4}. Luyten P, Andreu-Burillo I, Norro A, Ponsar S, Proctor R (2005) A new version of the European public domain code COHERENS. In: Proceedings of the fourth international conference on EuroGOOS, pp 474-481. Monbaliu, J., R. Padilla-Hernandez, J.C. Hargreaves, J.C.C. Albiach, W.M. Luo, M. Sclavo, and H. Gunther (2000). "The spectral wave model, WAM, adapted for applications with high spatial resolution". In: Coastal engineering 41.1-3, 41-62.issn: 0378-3839.doi:{10.1016/S0378-3839(00)00026-0}.

Development of Inundation Map for Bantayan Island, Cebu Using Delft3D-Flow Storm Surge Simulations of Typhoon Haiyan

NASA Astrophysics Data System (ADS)

Cuadra, Camille; Suarez, John Kenneth; Biton, Nophi Ian; Cabacaba, Krichi May; Lapidez, John Phillip; Santiago, Joy; Mahar Francisco Lagmay, Alfredo; Malano, Vicente

2014-05-01

On average, 20 typhoons enter the Philippine area of responsibility annually, making it vulnerable to different storm hazards. Apart from the frequency of tropical cyclones, the archipelagic nature of the country makes it particularly prone to storm surges. On 08 November 2013, Haiyan, a Category 5 Typhoon with maximum one-minute sustained wind speed of 315 kph, hit the central region of the Philippines. In its path, the howler devastated Bantayan Island, a popular tourist destination. The island is located north of Cebu City, the second largest metropolis of the Philippines in terms of populace. Having been directly hit by Typhoon Haiyan, Bantayan Island was severely damaged by strong winds and storm surges, with more than 11,000 houses totally destroyed while 5,000 more suffered minor damage. The adverse impacts of possible future storm surge events in the island can only be mitigated if hazard maps that depict inundation of the coastal areas of Bantayan are generated. To create such maps, Delft3D-Flow, a hydrodynamic model was used to simulate storm surges. These simulations were made over a 10-m per pixel resolution Digital Elevation Model (DEM) and the General Bathymetric Chart of the Oceans (GEBCO) bathymetry. The results of the coastal inundation model for Typhoon Haiyan's storm surges were validated using data collected from field work and local government reports. The hydrodynamic model of Bantayan was then calibrated using the field data and further simulations were made with varying typhoon tracks. This was done to generate scenarios on the farthest possible inland incursion of storm surges. The output of the study is a detailed storm surge inundation map that depicts safe zones for development of infrastructure near coastal areas and for construction of coastal protection structures. The storm surge inundation map can also be used as basis for disaster preparedness plans of coastal communities threatened by approaching typhoons.

Characteristics of ionospheric storms in East Asia

NASA Astrophysics Data System (ADS)

Wang, Xiao; Wang, Guojun; Shi, Jiankui

The ionosphere experiences intense response during the geomagnetic storm and it varies with latitude and longitude. The DPS-4 digisonde measurements and GPS-TEC data of ionospheric stations located at different latitudes in the longitudinal sector of 90-130E during 2002 to 2012 were analyzed to investigate the ionospheric effects in the different latitude of East Asia during geomagnetic storm. About 70 geomagnetic storms are selected according to the Dst index and observed data and they are in different seasons and different solar activity levels. A few quiet days’ averages of data before geomagnetic storm were used as the undisturbed level. Results show that for the middle and high latitude, the short-lived positive disturbance associated with the initial phase of the every storm was observed in each season and then the disturbances were negative till the termination of storm. At the low latitude, storm-time disturbances of foF2 have obvious diurnal, seasonal and solar cycle characteristics. Generally, geomagnetic activity will cause foF2 to increase at daytime and decrease at nighttime except for the summer in low solar activity period. The intensity of response of foF2 is stronger at nighttime than that at daytime. The negative ionospheric storm effect is the strongest in summer and the positive ionospheric storm effect is the strongest in winter. In high solar activity period, the diurnal variation of the response of foF2 is very pronounced in each season, and the strong ionospheric response can last several days. In low solar activity period, ionospheric response has very pronounced diurnal variation in winter only. It’s notable that geomagnetic activities occurred at local time nighttime can cause stronger and longer responses of foF2 at the low latitude. All in all, the obvious negative phase ionospheric storms often occurred at the low latitude. Moreover a notable phenomenon was observed for the low latitude, there are the intensive oscillations of foF2 occurring during the main storm phase of enhanced storm in Hainan, and it occurred in the morning generally. For the TEC data, strong disturbances can be observed simultaneously from high latitude to low latitude during the main phase of some storms. Generally strong/weak storms can cause the negative/positive phase storms of TEC in the low latitude and which are obvious in the daytime for the summer and winter and in the period from noon to midnight for the equinox. The differences of the responses of foF2 and TEC are also investigated.

Relationship between the trajectory of mid-latitude cyclones in the eastern Pacific Ocean and the isotopic composition of snowfall in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Vasquez, K. T.; Sickman, J. O.; Lucero, D. M.; Heard, A. M.

2014-12-01

Climate change has caused a change in the Sierra Nevada snowpack and the timing of its snowmelt, threatening a valuable water resource that provides for 25 million people and 5 million hectares of irrigated land. Understanding past and future variations in the snowpack is crucial in order to plan future water management. Of particular importance would be an archive of the variability of past snowfall, which can be recorded through the isotopic records found in local paleoproxies (e.g., diatoms). We propose to quantify the relationship between sources of atmospheric moisture in the Sierra Nevada and the isotopic composition of its snowpack to uncover whether isotopic variations recorded in paloearchives are a result of the isotopic composition of the precipitation, thereby showing whether these archives could serve as a reliable source of atmospheric moisture. Preliminary analysis conducted from December 2012 to March 2013 at Sequoia National Park resulted in statistically significant correlations between the isotopic composition of the winter snowfall and storm track trajectories. It was observed that storms originating from more northern latitudes had predominantly lighter isotopes (more negative δ 2H and δ18O) and sub-tropical/tropical Pacific storms showed more positive δ 2H and δ18O. This pattern reflects the isotopic gradient of the Pacific Ocean and can prove useful when interpreting the climatic significance of the δ2H and δ18O values in analyzed proxies. While our initial investigation was promising, the winter of 2012 -2013 was abnormally dry compared to long-term averages. Before directing our investigation to known paleoproxies, we aim to determine if the correlation between storm tracks and isotopic composition of precipitation holds in years with average and above average precipitation through analysis of archived samples from calendar years 2007 - 2011 from Giant Forest in Sequoia National Park (southern sierra) and Manzanita Lake in Lassen Volcanic National Park (northern sierra).

Forest structure and light regimes following moderate wind storms: implications for multi-cohort management.

PubMed

Hanson, Jacob J; Lorimer, Craig G

2007-07-01

Moderate-severity disturbances appear to be common throughout much of North America, but they have received relatively little detailed study compared to catastrophic disturbances and small gap dynamics. In this study, we examined the immediate impact of moderate-intensity wind storms on stand structure, opening sizes, and light regimes in three hemlock-hardwood forests of northeastern Wisconsin. These were compared to three stands managed by single-tree and group selection, the predominant forest management system for northern hardwoods in the region. Wind storms removed an average of 41% of the stand basal area, compared to 27% removed by uneven-aged harvests, but both disturbances removed trees from a wide range of size classes. The removal of nearly half of the large trees by wind in two old-growth stands caused partial retrogression to mature forest structure, which has been hypothesized to be a major disturbance pathway in the region. Wind storms resulted in residual stand conditions that were much more heterogeneous than in managed stands. Gap sizes ranged from less than 10 m2 up to 5000 m2 in wind-disturbed stands, whereas the largest opening observed in managed stands was only 200 m2. Wind-disturbed stands had, on average, double the available solar radiation at the forest floor compared to managed stands. Solar radiation levels were also more heterogeneous in wind-disturbed stands, with six times more variability at small scales (0.1225 ha) and 15 times more variability at the whole-stand level. Modification of uneven-aged management regimes to include occasional harvests of variable intensity and spatial pattern may help avoid the decline in species diversity that tends to occur after many decades of conventional uneven-aged management. At the same time, a multi-cohort system with these properties would retain a high degree of average crown cover, promote structural heterogeneity typical of old-growth forests, and maintain dominance by late-successional species.

L-band Microwave Remote Sensing and Land Data Assimilation Improve the Representation of Prestorm Soil Moisture Conditions for Hydrologic Forecasting

NASA Technical Reports Server (NTRS)

Crow, W. T.; Chen, F.; Reichle, R. H.; Liu, Q.

2017-01-01

Recent advances in remote sensing and land data assimilation purport to improve the quality of antecedent soil moisture information available for operational hydrologic forecasting. We objectively validate this claim by calculating the strength of the relationship between storm-scale runoff ratio (i.e., total stream flow divided by total rainfall accumulation in depth units) and pre-storm surface soil moisture estimates from a range of surface soil moisture data products. Results demonstrate that both satellite-based, L-band microwave radiometry and the application of land data assimilation techniques have significantly improved the utility of surface soil moisture data sets for forecasting stream flow response to future rainfall events.

Experimental study of hydraulics and sediment capture efficiency in catchbasins.

PubMed

Tang, Yangbo; Zhu, David Z; Rajaratnam, N; van Duin, Bert

2016-12-01

Catchbasins (also known as gully pot in the UK and Australia) are used to receive surface runoff and drain the stormwater into storm sewers. The recent interest in catchbasins is to improve their effectiveness in removing sediments in stormwater. An experimental study was conducted to examine the hydraulic features and sediment capture efficiency in catchbasins, with and without a bottom sump. A sump basin is found to increase the sediment capture efficiency significantly. The effect of inlet control devices, which are commonly used to control the amount of flow into the downstream storm sewer system, is also studied. These devices will increase the water depth in the catchbasin and increase the sediment capture efficiency. Equations are developed for predicting the sediment capture efficiency in catchbasins.

Statistical characterization of the Sub-Auroral Polarization Stream (SAPS)

NASA Astrophysics Data System (ADS)

Kunduri, B.; Baker, J. B.; Ruohoniemi, J. M.; Erickson, P. J.; Coster, A. J.; Oksavik, K.

2017-12-01

The Sub-Auroral Polarization Stream (SAPS) is a narrow region of westward directed plasma convection typically observed in the dusk-midnight sector equatorward of the main auroral oval. SAPS plays an important role in mid-latitude space weather dynamics and has a controlling influence on the evolution of large-scale plasma features, such as Storm Enhanced Density (SED) plumes. In this study, data from North American mid-latitude SuperDARN radars collected between January 2011 and December 2014 have been used to compile a database of SAPS events for statistical analysis. We examine the dependence of SAPS velocity magnitude and direction on geomagnetic activity and magnetic local time. The lowest speed limit and electric fields observed during SAPS are discussed and histograms of SAPS velocities for different Dst bins and MLAT-MLT locations are presented. We find significant differences in SAPS characteristics between periods of low and high geomagnetic activity, suggesting that SAPS are driven by different mechanisms during storm and non-storm conditions. To further explore this possibility, we have characterized the SAPS location and peak speed relative to the ionospheric trough specified by GPS Total Electron Content (TEC) data from the MIT Haystack Madrigal database. A particular emphasis is placed on identifying the extent to which the location, structure, and depth of the trough may play a controlling influence on SAPS speeds during storm and non-storm periods. The results are interpreted in terms of the current paradigm for active thermosphere-ionosphere feedback being an important component of SAPS physics.

Storm Surge Hazard in Oman Based on Cyclone Gonu and Historic Events

NASA Astrophysics Data System (ADS)

Blount, C.; Fritz, H. M.; Albusaidi, F. B.; Al-Harthy, A. H.

2008-12-01

Super Cyclone Gonu was the strongest tropical cyclone on record in the Arabian Sea. Gonu developed sustained winds reaching 240 km/h with gusts up to 315 km/h and an estimated central pressure of 920 mbar by late 4 June 2007 while centered east-southeast of Masirah Island on the coast of Oman. Gonu weakened after encountering dry air and cooler waters prior to the June 5 landfall on the eastern-most tip of Oman, becoming the strongest tropical cyclone to hit the Arabian Peninsula. Gonu dropped heavy rainfall near the eastern coastline, reaching up to 610 mm which caused wadi flooding and heavy damage. The shore parallel cyclone track resulted in coastal damage due to storm surge and storm wave impact along a 300km stretch of Omani coastline. Maximum high water marks, overland flow depths, and inundation distances were measured along the Gulf of Oman during the 1-4 August 2007 reconnaissance. The high water marks peaked at Ras al Hadd at the eastern tip of Oman exceeding 5 meters, surpassing 2004 Indian Ocean tsunami runup at every corresponding point. The cyclone caused $4 billion in damage and at least 49 deaths in the Sultanate of Oman. Prior to Gonu, only two similar cyclones struck the coast of Oman in the last 1200 years (in 865 and 1890). The 1890 storm, which remains the worst natural disaster in Oman's history, drenched the coast from Soor to Suwayq causing inland wadi flooding. Matrah and Muscat were the hardest hit areas with many ships being washed ashore and wrecked. The storm is known to have killed about 727 people and caused huge agricultural and shipping losses. Similarly, the 865 storm affected areas between Gobrah and Sohar. A high-resolution finite element ADCIRC mesh of the Arabian Sea is created to model storm surge and is coupled with STWAVE. Modeling results from Gonu are compared to measurements and used to determine the contribution from storm surge and waves. The 1890 and 865 storms are modeled with standard cyclone parameters and results are compared to historical records to estimate the storm tracks. These results can be used to assess the coastal vulnerability in the Gulf of Oman.

Satellite Studies of Storm-Time Thermospheric Winds

NASA Technical Reports Server (NTRS)

Fejer, Bela G.

2005-01-01

In this project we have studied the climatology and storm-time dependence of longitude-averaged mid- and low-latitude thermospheric neutral winds observed by the WINDII instrument on board the UARS satellite. This satellite is in a circular, 57 deg inclination orbit at a height of 585 km; the orbit precesses at a rate of 5 deg per day. WINDII is a Michelson interferometer that measures Doppler shifts of the green line (557.7 nm) and red line (630.0 nm) airglow emissions at the Earth's limb, covering latitudes up to 72 deg.

Hurricane & Tropical Storm Impacts over the South Florida Metropolitan Area: Mortality & Government

NASA Astrophysics Data System (ADS)

Colon Pagan, I. C.

2007-12-01

Since 1985, the South Florida Metropolitan area (SFMA), which covers the counties of Miami-Dade, Broward, and Palm Beach, has been directly affected by 9 tropical cyclones: four tropical storms and 5 hurricanes. This continuous hurricane and tropical storm activity has awakened the conscience of the communities, government, and private sector, about the social vulnerability, in terms of age, gender, ethnicity, and others. Several factors have also been significant enough to affect the vulnerability of the South Florida Metropolitan area, like its geographic location which is at the western part of the Atlantic hurricane track, with a surface area of 6,137 square miles, and elevation of 15 feet. And second, from the 2006 Census estimate, this metropolitan area is the 7th most populous area in the United States supporting almost 1,571 individuals per square mile. Mortality levels due to hurricanes and tropical storms have fluctuated over the last 21 years without any signal of a complete reduction, a phenomenon that can be related to both physical characteristics of the storms and government actions. The average annual death count remains almost the same from 4.10 between 1985 and 1995 to 4 from 1996 to 2006. However, the probability of occurrence of a direct impact of an atmospheric disturbance has increase from 0.3 to 0.6, with an average of three hurricane or tropical storm direct impacts for every five. This analysis suggests an increasing problem with regard to atmospheric disturbances-related deaths in the South Florida Metropolitan area. In other words, despite substantial increases in population during the last 21 years, the number of tropical cyclone-related deaths is not declining; it's just being segregated among more storms. Gaps between each impact can be related to mortality levels. When that time increases in five years or more, such as Bob and Andrew or Irene and Katrina, or decreases in weeks or months, such as Harvey and Irene or Katrina and Wilma, mortality also increases. A relief is also remarkable when that time is between one and four years, which might be related to better government actions during a certain period after a strong hurricane impact. Results reflect a lack of focus on hurricane and tropical storm related themes, while a decrease in funding can be the consequence of less interest and much more attention on less probable hazards with a long term recovery period. Even though the government has an important role in hurricanes and tropical storms mitigation, some of the main ideas to decrease mortality are focused in networking between private and public sector and the understanding of self-vulnerability of each individual.

Three-dimensional variational assimilation of MODIS aerosol optical depth: Implementation and application to a dust storm over East Asia

NASA Astrophysics Data System (ADS)

Liu, Zhiquan; Liu, Quanhua; Lin, Hui-Chuan; Schwartz, Craig S.; Lee, Yen-Huei; Wang, Tijian

2011-12-01

Assimilation of the Moderate Resolution Imaging Spectroradiometer (MODIS) total aerosol optical depth (AOD) retrieval products (at 550 nm wavelength) from both Terra and Aqua satellites have been developed within the National Centers for Environmental Prediction (NCEP) Gridpoint Statistical Interpolation (GSI) three-dimensional variational (3DVAR) data assimilation system. This newly developed algorithm allows, in a one-step procedure, the analysis of 3-D mass concentration of 14 aerosol variables from the Goddard Chemistry Aerosol Radiation and Transport (GOCART) module. The Community Radiative Transfer Model (CRTM) was extended to calculate AOD using GOCART aerosol variables as input. Both the AOD forward model and corresponding Jacobian model were developed within the CRTM and used in the 3DVAR minimization algorithm to compute the AOD cost function and its gradient with respect to 3-D aerosol mass concentration. The impact of MODIS AOD data assimilation was demonstrated by application to a dust storm from 17 to 24 March 2010 over East Asia. The aerosol analyses initialized Weather Research and Forecasting/Chemistry (WRF/Chem) model forecasts. Results indicate that assimilating MODIS AOD substantially improves aerosol analyses and subsequent forecasts when compared to MODIS AOD, independent AOD observations from the Aerosol Robotic Network (AERONET) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument, and surface PM10 (particulate matter with diameters less than 10 μm) observations. The newly developed AOD data assimilation system can serve as a tool to improve simulations of dust storms and general air quality analyses and forecasts.

Assessing the spatial variability of mountain precipitation in California's Sierra Nevada using the Airborne Snow Observatory

NASA Astrophysics Data System (ADS)

Brandt, T.; Deems, J. S.; Painter, T. H.; Dozier, J.

2016-12-01

In California's Sierra Nevada, 10 or fewer winter storms are responsible for most of the annual precipitation, which falls mostly as snow. Presently, surface stations are used to measure the dynamics of mountain precipitation. However, even in places like the Sierra Nevada—one of the most gauged regions in the world—the paucity of surface stations can lead to large errors in precipitation thereby biasing both total water year and short-term streamflow forecasts. Remotely sensed snow depth and water equivalent, at a time scale that resolves storms, might provide a novel solution to the problems of: (1) quantifying the spatial variability of mountain precipitation; and (2) assessing gridded precipitation products that are mostly based on surface station interpolation. NASA's Airborne Snow Observatory (ASO), an imaging spectrometer and LiDAR system, has measured snow in the Tuolumne River Basin in California's Sierra Nevada for the past four years, 2013-2016; and, measurements will continue. Principally, ASO monitors the progression of melt for water supply forecasting, nonetheless, a number of flights bracketed storms allowing for estimates of snow accumulation. In this study we examine a few of the ASO recorded storms to determine both the basin and subbasin orographic effect as well as the spatial patterns in total precipitation. We then compare these results to a number of gridded climate products and weather models including: Daymet, the Parameter-elevation Regressions on Independent Slopes Model (PRISM), the North American Land Data Assimilation System (NLDAS-2), and the Weather Research and Forecasting (WRF) model. Finally, to put each ASO recorded storm into context, we use a climatology produced from snow pillows and the North American Regional Reanalysis (NARR) for 2014-2016 to examine key accumulation events, and classify storms based on their integrated water vapor flux.

Colluvium supply in humid regions limits the frequency of storm-triggered landslides.

PubMed

Parker, Robert N; Hales, Tristram C; Mudd, Simon M; Grieve, Stuart W D; Constantine, José A

2016-09-30

Shallow landslides, triggered by extreme rainfall, are a significant hazard in mountainous landscapes. The hazard posed by shallow landslides depends on the availability and strength of colluvial material in landslide source areas and the frequency and intensity of extreme rainfall events. Here we investigate how the time taken to accumulate colluvium affects landslide triggering rate in the Southern Appalachian Mountains, USA and how this may affect future landslide hazards. We calculated the failure potential of 283 hollows by comparing colluvium depths to the minimum (critical) soil depth required for landslide initiation in each hollow. Our data show that most hollow soil depths are close to their critical depth, with 62% of hollows having soils that are too thin to fail. Our results, supported by numerical modeling, reveal that landslide frequency in many humid landscapes may be insensitive to projected changes in the frequency of intense rainfall events.

Colluvium supply in humid regions limits the frequency of storm-triggered landslides

PubMed Central

Parker, Robert N.; Hales, Tristram C.; Mudd, Simon M.; Grieve, Stuart W. D.; Constantine, José A.

2016-01-01

Shallow landslides, triggered by extreme rainfall, are a significant hazard in mountainous landscapes. The hazard posed by shallow landslides depends on the availability and strength of colluvial material in landslide source areas and the frequency and intensity of extreme rainfall events. Here we investigate how the time taken to accumulate colluvium affects landslide triggering rate in the Southern Appalachian Mountains, USA and how this may affect future landslide hazards. We calculated the failure potential of 283 hollows by comparing colluvium depths to the minimum (critical) soil depth required for landslide initiation in each hollow. Our data show that most hollow soil depths are close to their critical depth, with 62% of hollows having soils that are too thin to fail. Our results, supported by numerical modeling, reveal that landslide frequency in many humid landscapes may be insensitive to projected changes in the frequency of intense rainfall events. PMID:27688039

Peak-flow frequency and extreme flood potential for streams in the vicinity of the Highland Lakes, central Texas

USGS Publications Warehouse

Asquith, William H.; Slade, R.M.; Lanning-Rush, Jennifer

1996-01-01

The Highland Lakes on the Colorado River are in an area periodically threatened by large storms and floods. Many storms exceeding 10 inches (in.) in depth have been documented in the area, including some with depths approaching 40 in. These storms typically produce large peak discharges that often threaten lives and property. The storms sometimes occur with little warning. Steep stream slopes and thin soils characteristic of the area often cause large peak discharges and rapid movement of floods through watersheds. A procedure to predict the discharge associated with large floods is needed for the area so that appropriate peak discharges can be used in the design of flood plains, bridges, and other structures.The U.S. Geological Survey (USGS), in cooperation with the Lower Colorado River Authority (LCRA), studied flood peaks for streams in the vicinity of the Highland Lakes of central Texas. The Highland Lakes are a series of reservoirs constructed on the Colorado River. The chain of lakes (and year each was completed) comprises Lake Buchanan (1937), Inks Lake (1938), Lake Lyndon B. Johnson (1950), Lake Marble Falls (1951), Lake Travis (1942), and lake Austin (1890). The study area (fig. 1), which includes all or parts of 21 counties in the vicinity of the Highland Lakes, was selected because most streams in the area have flood characteristics similar to streams entering the Highland Lakes. The entire study area is in a region subject to large storms.The purpose of this report is to present (1) peak-flow frequency data for stations and equations to estimate peak-flow frequency for large streams with natural drainage basins in the vicinity of the Highland Lakes, and (2) a technique to estimate the extreme flood peak discharges for the large streams in the vicinity of the Highland Lakes. Peak-flow frequency in this report refers to the peak discharges for recurrence intervals of 2,5, 10,25,50, and 100 years. A large stream is defined as having a contributing drainage area of at least0.5 square mile (mi’); and a natural drainage basin has less than 10 percent impervious cover and less than 10 percent of its drainage area controlled by reservoirs.The mean annual precipitation in the study area for 1951–80 ranges from about 20 in, in western Kimble County to about 34 in. at the eastern edge of Williamson County (Riggio and others, 1987, p. 23). Many large storms and catastrophic floods have occurred along or in the adjacent area west of the Balcones escarpment (fig. 1) (Dalrymple and others, 1939, Breeding and Dalrymple, 1944; Breeding and Montgomery, 1954; Schroeder and others, 1979; Caran and Baker, 1986; Slade, 1986; and Hejl and others, 1996). About a dozen storms with precipitation depths exceeding 15 in. in a few days or less have been documented in this area during the past 60 years. Some of these storms have produced world-record precipitation depths for durations less than 48 hours. The documentation for these and for other large storms indicates that they are not uniformly distributed temporally or spatially; therefore, the recurrence intervals for such storms cannot be verified (Slade, 1986, p. 17). These large storms can cause flood peaks that would exceed those that can be predicted accurately by analyses of available precipitation or flood data.The peak-flow frequency was estimated for each of 55 qualified stations in the study area (table 1) following guidelines established by the Interagency Advisory Committee on Water Data (1982). Qualified streamflow-gaging stations for the study area are those with at least 8 years of data from natural drainage basins (sites 1–55, fig. 1). Equations to estimate peak-flow frequency for large streams with natural drainage basins in the vicinity of the Highland Lakes were developed. These equations were developed from selected stations on the basis of the relation between peak-flow frequency and basin characteristics for each station. The entire period of systematic record (through 1993) was used in the frequency analyses for each qualified station except for stations at which streamflow was regulated during part of the record. These stations are Leon River near Belton (site 1): Lampasas River near Youngsport (site 5); North Fork San Gabriel River near Georgetown (site 6); San Gabriel River at Laneport (site 12); Brady Creek at Brady (site 16); San Saba River at San Saba (site 18); Rebecca Creek near Spring Branch (site 51); and Cibolo Creek near Boerne (site 54). One or more reservoirs were completed in the basin of each of these stations during the period of systematic record. These reservoirs caused the annual peak discharges to become regulated. The annual peak discharges for 1994 and 1995 at Sandy Creek near Kingsland (site 28) were used to include data associated with extreme flooding that occurred in 1995.The extreme flood potential in the study area was investigated using an "envelope" or "extreme flood potential" curve. This curve is based on the relation between the contributing drainage area and (1) the maximum peak discharge of record for each qualified station (table 1); (2) substantial peak discharges documented for 84 sites without stations (sites 56–139, fig. 1, table 2); and (3) 100-year peak discharges from peak-flow frequency for stations (table 1). Peak discharges estimated from this curve represent the extreme flood potential for the study area.

Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)

USGS Publications Warehouse

Haase, K.B.; Jordan, C.; Mentis, E.; Cottrell, L.; Mayne, H.R.; Talbot, R.; Sive, B.C.

2011-01-01

Monoterpenes are an important class of biogenic hydrocarbons that influence ambient air quality and are a principle source of secondary organic aerosol (SOA). Emitted from vegetation, monoterpenes are a product of photosynthesis and act as a response to a variety of environmental factors. Most parameterizations of monoterpene emissions are based on clear weather models that do not take into account episodic conditions that can drastically change production and release rates into the atmosphere. Here, the ongoing monoterpene dataset from the rural Thompson Farm measurement site in Durham, New Hampshire is examined in the context of a set of known severe storm events. While some storm systems had a negligible influence on ambient monoterpene mixing ratios, the average storm event increased mixing ratios by 0.59 ?? 0.21 ppbv, a factor of 93 % above pre-storm levels. In some events, mixing ratios reached the 10's of ppbv range and persisted overnight. These mixing ratios correspond to increases in the monoterpene emission rate, ranging from 120 to 1240 g km-2 h -1 compared to an estimated clear weather rate of 116 to 193 g km-2 h-1. Considering the regularity of storm events over most forested areas, this could be an important factor to consider when modeling global monoterpene emissions and their resulting influence on the formation of organic aerosols. ?? 2011 Author(s).

Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)

USGS Publications Warehouse

Haase, Karl B.; Jordan, C.; Mentis, E.; Cottrell, L.; Mayne, H.R.; Talbot, R.; Sive, B.C.

2011-01-01

Monoterpenes are an important class of biogenic hydrocarbons that influence ambient air quality and are a principle source of secondary organic aerosol (SOA). Emitted from vegetation, monoterpenes are a product of photosynthesis and act as a response to a variety of environmental factors. Most parameterizations of monoterpene emissions are based on clear weather models that do not take into account episodic conditions that can drastically change production and release rates into the atmosphere. Here, the monoterpene dataset from the rural Thompson Farm measurement site in Durham, New Hampshire is examined in the context of a set of known severe storm events. While some storm systems had a negligible influence on ambient monoterpene mixing ratios, the average storm event increased mixing ratios by 0.59 ?? 0.21 ppbv, a factor of 93% above pre-storm levels. In some events, mixing ratios reached the 10's of ppbv range and persisted overnight. These mixing ratios correspond to increases in the monoterpene emission rate, ranging from 120 to 1240 g km-2 h -1 compared to an estimated clear weather rate of 116 to 193 g km-2 h-1. Considering the regularity of storm events over most forested areas, this could be an important factor to consider when modeling global monoterpene emissions and their resulting influence on the formation of organic aerosols.

Parameterization of synoptic weather systems in the South Atlantic Bight for modeling applications

NASA Astrophysics Data System (ADS)

Wu, Xiaodong; Voulgaris, George; Kumar, Nirnimesh

2017-10-01

An event based, long-term, climatological analysis is presented that allows the creation of coastal ocean atmospheric forcing on the coastal ocean that preserves both frequency of occurrence and event time history. An algorithm is developed that identifies individual storm event (cold fronts, warm fronts, and tropical storms) from meteorological records. The algorithm has been applied to a location along the South Atlantic Bight, off South Carolina, an area prone to cyclogenesis occurrence and passages of atmospheric fronts. Comparison against daily weather maps confirms that the algorithm is efficient in identifying cold fronts and warm fronts, while the identification of tropical storms is less successful. The average state of the storm events and their variability are represented by the temporal evolution of atmospheric pressure, air temperature, wind velocity, and wave directional spectral energy. The use of uncorrected algorithm-detected events provides climatologies that show a little deviation from those derived using corrected events. The effectiveness of this analysis method is further verified by numerically simulating the wave conditions driven by the characteristic wind forcing and comparing the results with the wave climatology that corresponds to each storm type. A high level of consistency found in the comparison indicates that this analysis method can be used for accurately characterizing event-based oceanic processes and long-term storm-induced morphodynamic processes on wind-dominated coasts.

Contribution of recent hurricanes to wetland sedimentation in coastal Louisiana

NASA Astrophysics Data System (ADS)

Liu, Kam-biu; Bianchette, Thomas; Zou, Lei; Qiang, Yi; Lam, Nina

2017-04-01

Hurricanes are important agents of sediment deposition in the wetlands of coastal Louisiana. Since Hurricanes Katrina and Rita of 2005, coastal Louisiana has been impacted by Hurricanes Gustav (2008), Ike (2008), and Isaac (2012). By employing the principles and methods of paleotempestology we have identified the storm deposits attributed to the three most recent hurricanes in several coastal lakes and swamps in Louisiana. However, the spatial distribution and volume of these storm depositions cannot be easily inferred from stratigraphic data derived from a few locations. Here we report on results from a GIS study to analyze the spatial and temporal patterns of storm deposition based on data extracted from the voluminous CRMS (Coastal Reference Monitoring System) database, which contains vertical accretion rate measurements obtained from 390 wetland sites over various time intervals during the past decade. Wetland accretion rates averaged about 2.89 cm/yr from stations sampled before Hurricane Isaac, 4.04 cm/yr during the 7-month period encompassing Isaac, and 2.38 cm/yr from sites established and sampled after Isaac. Generally, the wetland accretion rates attributable to the Isaac effects were 40% and 70% greater than before and after the event, respectively. Accretion rates associated with Isaac were highest at wetland sites along the Mississippi River and its tributaries instead of along the path of the hurricane, suggesting that freshwater flooding from fluvial channels, enhanced by the storm surge from the sea, is the main mechanism responsible for increased accretion in the wetlands. Our GIS work has recently been expanded to include other recent hurricanes. Preliminary results indicate that, for non-storm periods, the average wetland accretion rates between Katrina/Rita and Gustav/Ike was 2.58 cm/yr; that between Gustav/Ike and Isaac was 1.95 cm/yr; and that after Isaac was 2.37 cm/yr. In contrast, the accretion rates attributable to the effects of Gustav/Ike and Isaac were 4.41 cm/yr and 3.52 cm/yr, respectively. These results show that hurricane-related accretion rates in wetlands are 50 - 225% higher than the normal rates typical of non-storm periods.

Depth distribution of microbial production and oxidation of methane in northern boreal peatlands.

PubMed

Sundh, I; Nilsson, M; Granberg, G; Svensson, B H

1994-05-01

The depth distributions of anaerobic microbial methane production and potential aerobic microbial methane oxidation were assessed at several sites in both Sphagnum- and sedge-dominated boreal peatlands in Sweden, and compared with net methane emissions from the same sites. Production and oxidation of methane were measured in peat slurries, and emissions were measured with the closed-chamber technique. Over all eleven sites sampled, production was, on average, highest 12 cm below the depth of the average water table. On the other hand, highest potential oxidation of methane coincided with the depth of the average water table. The integrated production rate in the 0-60 cm interval ranged between 0.05 and 1.7 g CH4 m (-2) day(-) and was negatively correlated with the depth of the average water table (linear regression: r (2) = 0.50, P = 0.015). The depth-integrated potential CH4-oxidation rate ranged between 3.0 and 22.1 g CH4 m(-2) day(-1) and was unrelated to the depth of the average water table. A larger fraction of the methane was oxidized at sites with low average water tables; hence, our results show that low net emission rates in these environments are caused not only by lower methane production rates, but also by conditions more favorable for the development of CH4-oxidizing bacteria in these environments.

Modeling Street-Level Inundation in Galveston, Texas City, and Houston during 2008 Hurricane Ike: Now and Implications for the Future

NASA Astrophysics Data System (ADS)

Loftis, D.

2016-02-01

In the wake of Hurricane Katrina (2005), Hurricane Ike (2008) is the second most devastating tropical cyclone to make landfall in the Gulf of Mexico in recent history. The path of the eye of Hurricane Ike passing directly over the Galveston's City Center requires the finesse of a street-level hydrodynamic model to accurately resolve the spatial inundation extent observed during the storm. A version of the Holland wind model was coupled with a sub-grid hydrodynamic model to address the complexity of spatially-varying hurricane force winds on the irregular movement of fluid though the streets of the coastal cities adjacent to the Galveston Bay. Sub-grid modeling technology is useful for incorporating high-resolution lidar-derived elevation measurements into the conventional hydrodynamic modeling framework to resolve detailed topographic features for inclusion in a hydrological transport model for storm surge simulations. Buildings were mosaicked into a lidar-derived Digital Surface Model at 5m spatial resolution for the study area, and in turn, embedded within a sub-grid layer of the hydrodynamic model mesh in a cross-scale approach to address the movement of Ike's storm surge from the Gulf of Mexico through the Galveston Bay, up estuaries and onto land. Model predictions for timing and depth of flooding during Hurricane Ike were compared with 8 verified water level gauges throughout the study area to evaluate the effectiveness of the sub-grid model's partial wetting and drying scheme. Statistical comparison yielded a mean R2 of 0.914, a relative error of 4.19%, and a root-mean-squared error of 19.47cm. A rigorous point-to-point comparison between street-level model results and 217 high water mark observations collected by the USGS and FEMA at several sites after the storm revealed that the model predicted the depth of inundation comparably well with an aggregate root-mean-squared error 0.283m. Finally, sea-level rise scenarios using Hurricane Ike as a base case revealed future storm-induced inundation could extend 0.6-2.8 km inland corresponding to increases in mean sea level of 37.5-150 cm based upon IPCC climate change prediction scenarios specified in their 5th assessment report in 2013.

Radiative impact of a heavy dust storm over India and surrounding oceanic regions

NASA Astrophysics Data System (ADS)

Kedia, Sumita; Kumar, Rajesh; Islam, Sahidul; Sathe, Yogesh; Kaginalkar, Akshara

2018-07-01

Efficient management of frequently occurring destructive dust storms requires an in-depth understanding of the extent of impacts of such events. Due to limited availability of observational data, it is difficult to understand/estimate the impact of dust aerosols on the Earth's radiation budget in detail. This study, applies a regional model, Weather Research and Forecasting model with chemistry (WRF-Chem), to investigate the impact of an intense dust storm that originated over the Arabian peninsula during 01-02 April 2015 and transported towards the Indian subcontinent by the westerly winds. Two identical numerical experiments are designed, each for 15 days, one with and another without dust aerosols, to estimate the impact of the dust storm over the Indian subcontinent and adjoining regions. WRF-Chem model reproduced the spatial, temporal as well as the vertical distribution of dust plume reasonably well. Model results show significant changes in aerosol optical, physical and radiative properties due to the dominance of coarse mode aerosols in the atmosphere during the dust storm. Analysis of vertical profiles of particulate matter (PM10) concentration reveals the presence of dust aerosols extending from the surface to altitudes as high as 3-4 km during the dust storm period. The dust storm induced a cooling effect at the surface via reduction in shortwave (SW) radiative flux. A substantial decrease in temperature is also seen at 850 hPa due to dust, indicating a significant impact of dust layer on the atmospheric temperature profile. Atmospheric heating due to dust aerosols in the SW region is found to be compensated up to a large extent by longwave (LW) cooling effect of dust. The net dust induced radiative perturbation at the top of the atmosphere (TOA) over different regions is negative and varied from -2.49 to -0.34 Wm-2, while it is in the range of -0.62 to + 0.32 Wm-2 at the surface.

4 Living roofs in 3 locations: Does configuration affect runoff mitigation?

NASA Astrophysics Data System (ADS)

Fassman-Beck, Elizabeth; Voyde, Emily; Simcock, Robyn; Hong, Yit Sing

2013-05-01

Four extensive living roofs and three conventional (control) roofs in Auckland, New Zealand have been evaluated over periods of 8 months to over 2 yrs for stormwater runoff mitigation. Up to 56% cumulative retention was measured from living roofs with 50-150 mm depth substrates installed over synthetic drainage layers, and with >80% plant coverage. Variation in cumulative %-retention amongst sites is attributed to different durations of monitoring, rather than actual performance. At all sites, runoff rarely occurred at all from storms with less than 25 mm of precipitation, from the combined effects of substrates designed to maximize moisture storage and because >90% of individual events were less than 25 mm. Living roof runoff depth per event is predicted well by a 2nd order polynomial model (R2 = 0.81), again demonstrating that small storms are well managed. Peak flow per event from the living roofs was 62-90% less than a corresponding conventional roof's runoff. Seasonal retention performance decreased slightly in winter, but was nonetheless substantial, maintaining 66% retention at one site compared to 45-93% in spring-autumn at two sites. Peak flow mitigation did not vary seasonally. During a 4-month period of concurrent monitoring at all sites, varied substrate depth did not influence runoff depth (volume), %-retention, or %-peak flow mitigation compared to a control roof at the same site. The magnitude of peak flow was greater from garden shed-scale living roofs compared to the full-scale living roofs. Two design aspects that could be manipulated to increase peak flow mitigation include lengthening the flow path through the drainage layer to vertical gutters and use of flow-retarding drainage layer materials.

Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere-ocean-wave model

NASA Astrophysics Data System (ADS)

Prakash, Kumar Ravi; Nigam, Tanuja; Pant, Vimlesh

2018-04-01

A coupled atmosphere-ocean-wave model was used to examine mixing in the upper-oceanic layers under the influence of a very severe cyclonic storm Phailin over the Bay of Bengal (BoB) during 10-14 October 2013. The coupled model was found to improve the sea surface temperature over the uncoupled model. Model simulations highlight the prominent role of cyclone-induced near-inertial oscillations in subsurface mixing up to the thermocline depth. The inertial mixing introduced by the cyclone played a central role in the deepening of the thermocline and mixed layer depth by 40 and 15 m, respectively. For the first time over the BoB, a detailed analysis of inertial oscillation kinetic energy generation, propagation, and dissipation was carried out using an atmosphere-ocean-wave coupled model during a cyclone. A quantitative estimate of kinetic energy in the oceanic water column, its propagation, and its dissipation mechanisms were explained using the coupled atmosphere-ocean-wave model. The large shear generated by the inertial oscillations was found to overcome the stratification and initiate mixing at the base of the mixed layer. Greater mixing was found at the depths where the eddy kinetic diffusivity was large. The baroclinic current, holding a larger fraction of kinetic energy than the barotropic current, weakened rapidly after the passage of the cyclone. The shear induced by inertial oscillations was found to decrease rapidly with increasing depth below the thermocline. The dampening of the mixing process below the thermocline was explained through the enhanced dissipation rate of turbulent kinetic energy upon approaching the thermocline layer. The wave-current interaction and nonlinear wave-wave interaction were found to affect the process of downward mixing and cause the dissipation of inertial oscillations.

The Association between Dust Storms and Daily Non-Accidental Mortality in the United States, 1993-2005.

PubMed

Crooks, James Lewis; Cascio, Wayne E; Percy, Madelyn S; Reyes, Jeanette; Neas, Lucas M; Hilborn, Elizabeth D

2016-11-01

The impact of dust storms on human health has been studied in the context of Asian, Saharan, Arabian, and Australian storms, but there has been no recent population-level epidemiological research on the dust storms in North America. The relevance of dust storms to public health is likely to increase as extreme weather events are predicted to become more frequent with anticipated changes in climate through the 21st century. We examined the association between dust storms and county-level non-accidental mortality in the United States from 1993 through 2005. Dust storm incidence data, including date and approximate location, are taken from the U.S. National Weather Service storm database. County-level mortality data for the years 1993-2005 were acquired from the National Center for Health Statistics. Distributed lag conditional logistic regression models under a time-stratified case-crossover design were used to study the relationship between dust storms and daily mortality counts over the whole United States and in Arizona and California specifically. End points included total non-accidental mortality and three mortality subgroups (cardiovascular, respiratory, and other non-accidental). We estimated that for the United States as a whole, total non-accidental mortality increased by 7.4% (95% CI: 1.6, 13.5; p = 0.011) and 6.7% (95% CI: 1.1, 12.6; p = 0.018) at 2- and 3-day lags, respectively, and by an average of 2.7% (95% CI: 0.4, 5.1; p = 0.023) over lags 0-5 compared with referent days. Significant associations with non-accidental mortality were estimated for California (lag 2 and 0-5 day) and Arizona (lag 3), for cardiovascular mortality in the United States (lag 2) and Arizona (lag 3), and for other non-accidental mortality in California (lags 1-3 and 0-5). Dust storms are associated with increases in lagged non-accidental and cardiovascular mortality. Citation: Crooks JL, Cascio WE, Percy MS, Reyes J, Neas LM, Hilborn ED. 2016. The association between dust storms and daily non-accidental mortality in the United States, 1993-2005. Environ Health Perspect 124:1735-1743; http://dx.doi.org/10.1289/EHP216.

Geomagnetic storms, the Dst ring-current myth and lognormal distributions

USGS Publications Warehouse

Campbell, W.H.

1996-01-01

The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30 years ago at the start of space exploration and the discovery of the Van Allen belt of particles encircling the Earth. The Dst global 'ring-current' index of geomagnetic disturbances, formulated in that period, is still taken to be the definitive representation for geomagnetic storms. Dst indices, or data from many world observatories processed in a fashion paralleling the index, are used widely by researchers relying on the assumption of such a magnetospheric current-ring depiction. Recent in situ measurements by satellites passing through the ring-current region and computations with disturbed magnetosphere models show that the Dst storm is not solely a main-phase to decay-phase, growth to disintegration, of a massive current encircling the Earth. Although a ring current certainly exists during a storm, there are many other field contributions at the middle-and low-latitude observatories that are summed to show the 'storm' characteristic behavior in Dst at these observatories. One characteristic of the storm field form at middle and low latitudes is that Dst exhibits a lognormal distribution shape when plotted as the hourly value amplitude in each time range. Such distributions, common in nature, arise when there are many contributors to a measurement or when the measurement is a result of a connected series of statistical processes. The amplitude-time displays of Dst are thought to occur because the many time-series processes that are added to form Dst all have their own characteristic distribution in time. By transforming the Dst time display into the equivalent normal distribution, it is shown that a storm recovery can be predicted with remarkable accuracy from measurements made during the Dst growth phase. In the lognormal formulation, the mean, standard deviation and field count within standard deviation limits become definitive Dst storm parameters.

Ionospheric irregularities over Bahir Dar, Ethiopia during selected geomagnetic storms

NASA Astrophysics Data System (ADS)

Kassa, Tsegaye; Damtie, Baylie

2017-07-01

We have analyzed the effect of geomagnetic storms on the occurrence of ionospheric irregularities by considering seven case studies in the period of 2013-2014 over Bahir Dar, Ethiopia (11° N , 38° E). We inferred the irregularity indices from GPS phase fluctuation by computing the median of 1-min rate of change of total electron content (fp) along the ray paths from all satellites observed. The Fp -index was calculated as an hourly average fp -index values along the ray paths from all satellites observed during each hour. Our results revealed that the irregularity level was inhibited during post sunset hours of the main phase of the storms we considered. On average, the irregularity index has dropped from 400 (0.4 TECU/min) during quiet time to 50 (0.05 TECU/min) on disturbed time with an amount of 350 (0.35 TECU/min). However, in some of the cases, immediately after the onset of the storm, we observed the enhancement of irregularities. We found that only the observations on 01 June 2013 and 19 February 2014 exhibited a correspondence of the time of occurrence of the minimum of the Dst-index with inhibition of irregularities noted by other researchers. Our observations of the enhancement of irregularities on 17 March 2013 and 19 February 2014 can partly be explained by the orientation of the IMF BZ . Other measurements such as neutral wind, electric field are required to explain the observations on 29 June 2013, 06 July 2013, 09 November 2013 and 27 February 2014.

Ecological Restoration Programs Induced Amelioration of the Dust Pollution in North China Plain

NASA Astrophysics Data System (ADS)

Long, X.; Tie, X.; Li, G.; Junji, C.

2017-12-01

With Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product (MCD12Q1), we quantitatively evaluate the ecological restoration programs (ERP) induced land cover change in China by calculating gridded the land use fraction (LUF). We clearly capture two obvious vegetation (grass and forest) protective barriers arise between the dust source region DSR and North China Plain NCP from 2011 to 2013. The WRF-DUST model is applied to investigate the impact of ERPs on dust pollution from 2 to 8 March 2016, corresponding to a national dust storm event over China. Despite some model biases, the WRF-DUST model reasonably reproduced the temporal variations of dust storm event, involving IOA of 0.96 and NMB of 2% for DSR, with IOA of 0.83 and NMB of -15% for downwind area of NCP. Generally, the WRF-DUST model well capture the spatial variations and evolutions of dust storm events with episode-average [PMC] correlation coefficient (R) of 0.77, especially the dust storm outbreak and transport evolution, involving daily average [PMC] R of 0.9 and 0.73 on 4-5 March, respectively. It is found that the ERPs generally reduce the dust pollution in NCP, especially for BTH, involving upper dust pollution control benefits of -15.3% (-21.0 μg m-3) for BTH, and -6.2% (-9.3 μg m-3) for NCP. We are the first to conduct model sensitivity studies to quantitatively evaluate the impacts of the ERPs on the dust pollution in NCP. And our narrative is independently based on first-hand sources, whereas government statistics.

Observational evidence for the convective transport of dust over the Central United States

NASA Astrophysics Data System (ADS)

Corr, C. A.; Ziemba, L. D.; Scheuer, E.; Anderson, B. E.; Beyersdorf, A. J.; Chen, G.; Crosbie, E.; Moore, R. H.; Shook, M.; Thornhill, K. L.; Winstead, E.; Lawson, R. P.; Barth, M. C.; Schroeder, J. R.; Blake, D. R.; Dibb, J. E.

2016-02-01

Bulk aerosol composition and aerosol size distributions measured aboard the DC-8 aircraft during the Deep Convective Clouds and Chemistry Experiment mission in May/June 2012 were used to investigate the transport of mineral dust through nine storms encountered over Colorado and Oklahoma. Measurements made at low altitudes (<5 km mean sea level (MSL)) in the storm inflow region were compared to those made in cirrus anvils (altitude > 9 km MSL). Storm mean outflow Ca2+ mass concentrations and total coarse (1 µm < diameter < 5 µm) aerosol volume (Vc) were comparable to mean inflow values as demonstrated by average outflow/inflow ratios greater than 0.5. A positive relationship between Ca2+, Vc, ice water content, and large (diameter > 50 µm) ice particle number concentrations was not evident; thus, the influence of ice shatter on these measurements was assumed small. Mean inflow aerosol number concentrations calculated over a diameter range (0.5 µm < diameter < 5.0 µm) relevant for proxy ice nuclei (NPIN) were ~15-300 times higher than ice particle concentrations for all storms. Ratios of predicted interstitial NPIN (calculated as the difference between inflow NPIN and ice particle concentrations) and inflow NPIN were consistent with those calculated for Ca2+ and Vc and indicated that on average less than 10% of the ingested NPIN were activated as ice nuclei during anvil formation. Deep convection may therefore represent an efficient transport mechanism for dust to the upper troposphere where these particles can function as ice nuclei cirrus forming in situ.

Combined Aircraft and Satellite-Derived Storm Electric Current and Lightning Rates Measurements and Implications for the Global Electric Circuit

NASA Technical Reports Server (NTRS)

Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

2010-01-01

Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of electrified shower clouds and thunderstorms spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, with and without lightning, and with positive and negative fields above the storms. The measurements were made with the NASA ER-2 and the Altus-II high altitude aircrafts. Peak electric fields, with lightning transients removed, ranged from -1.0 kV/m to 16 kV/m, with a mean value of 0.9 kV/m. The median peak field was 0.29 kV/m. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean storms with lightning is 1.6 A while the mean current for land storms with lightning is 1.0 A. The mean current for oceanic storms without lightning (i.e., electrified shower clouds) is 0.39 A and the mean current for land storms without lightning is 0.13 A. Thus, on average, land storms with or without lightning have about half the mean current as their corresponding oceanic storm counterparts. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal lightning statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. This excellent agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 0.7 kA (ocean) and 1.1 kA (land) from lightning-producing storms, and 0.22 kA (ocean) and 0.04 (land) from electrified shower clouds, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Breaking the results down into mean storm counts reveals 1100 for land storms with lightning, 530 for ocean storms without lightning, 390 for ocean storms with lightning, and 330 for land storms without lightning.

Mobilization of pesticides on an agricultural landscape flooded by a torrential storm.

PubMed

Donald, David B; Hunter, Fraser G; Sverko, Ed; Hill, Bernard D; Syrgiannis, Jim

2005-01-01

Mobilization of pesticides into surface waters of flooded agricultural landscapes following extreme precipitation events has not been previously investigated. After receiving 96 mm of rain in the previous 45 d, the Vanguard area of southeastern Saskatchewan, Canada, was subjected to a torrential storm on July 3, 2000, that produced as much as 375 mm of rain in 8 h. The majority of herbicides, but no insecticides, would have been applied to crops in the Vanguard area during the four weeks preceding the storm. After the storm, 19 herbicides and insecticides were detected in flooded wetlands, with 14 of them detected in 50% or more of wetlands. Average concentrations ranged from 0.43 ng/L (endosulfan) to 362 ng/L (2,4-dichlorophenoxyacedic acid). The pesticides probably were from long-range transport, followed by deposition in rain, and from herbicides applied to crops within the area subjected to the storm (1,700 km2). In the following year, when only 62 mm of rain fell in the same 45 d, only five pesticides were detected in 50% or more of wetlands. We estimated that for the 1,700-km2 storm zone, 278 kg of herbicide were mobilized into rain and by runoff into surface waters, and 105 kg were removed from the Vanguard area by discharge into Notukeu Creek. Significant quantities of herbicides are mobilized to aquatic environments when prairie agricultural landscapes are subjected to torrential storms. In these circumstances, flooded wells and small municipal reservoirs used as sources of drinking water may be compromised by 10 or more pesticides, some at relatively high concentrations.

Determining storm sampling requirements for improving precision of annual load estimates of nutrients from a small forested watershed.

PubMed

Ide, Jun'ichiro; Chiwa, Masaaki; Higashi, Naoko; Maruno, Ryoko; Mori, Yasushi; Otsuki, Kyoichi

2012-08-01

This study sought to determine the lowest number of storm events required for adequate estimation of annual nutrient loads from a forested watershed using the regression equation between cumulative load (∑L) and cumulative stream discharge (∑Q). Hydrological surveys were conducted for 4 years, and stream water was sampled sequentially at 15-60-min intervals during 24 h in 20 events, as well as weekly in a small forested watershed. The bootstrap sampling technique was used to determine the regression (∑L-∑Q) equations of dissolved nitrogen (DN) and phosphorus (DP), particulate nitrogen (PN) and phosphorus (PP), dissolved inorganic nitrogen (DIN), and suspended solid (SS) for each dataset of ∑L and ∑Q. For dissolved nutrients (DN, DP, DIN), the coefficient of variance (CV) in 100 replicates of 4-year average annual load estimates was below 20% with datasets composed of five storm events. For particulate nutrients (PN, PP, SS), the CV exceeded 20%, even with datasets composed of more than ten storm events. The differences in the number of storm events required for precise load estimates between dissolved and particulate nutrients were attributed to the goodness of fit of the ∑L-∑Q equations. Bootstrap simulation based on flow-stratified sampling resulted in fewer storm events than the simulation based on random sampling and showed that only three storm events were required to give a CV below 20% for dissolved nutrients. These results indicate that a sampling design considering discharge levels reduces the frequency of laborious chemical analyses of water samples required throughout the year.

Modeling Storm-Induced Inundation on the Yukon-Kuskokwim Delta for Present and Future Climates

NASA Astrophysics Data System (ADS)

Ravens, T. M.; Allen, J.

2012-12-01

The Yukon-Kuskokwim (YK) Delta is a large delta on the west coast of Alaska and one of the few remaining deltas that is largely free of anthropogenic impacts. The delta hosts a wide-range of nesting birds including the endangered Spectacled Eider. The delta plain, with an elevation of about 2 m (m.s.l.) - and an average tidal range of 2.7 m - is subject to frequent inundation by storm surges originating from the adjacent Bering Sea. Here, we report on our efforts to validate a storm-surge modeling system consisting of a course-grid ADCIRC model covering the Bering and Chukchi Seas and a Delft3D fine-grid model of the southern YK Delta. The storm surge models are validated based on measured water levels from 2007-2010 and using satellite observations of inundation due to large storms in 2005 and 2006. About 10 storms over the past 30 years are modeled. Based on model output, we computed a spatially distributed inundation index which is a time-integral of water level throughout the fine-grid model domain from individual storms and from the 30 year period. In order to examine the change in inundation in future climates, the models of the 30 year period were re-run assuming a 1 and 2 meter sea level rise. The impact of climate change on inundation frequency and intensity - using the inundation index - is reported. Future work will relate the present and projected inundation index to ecological parameters such as bird-nest concentration and vegetation type.

A subsynoptic-scale kinetic energy study of the Red River Valley tornado outbreak (AVE-SESAME 1)

NASA Technical Reports Server (NTRS)

Jedlovec, G. J.; Fuelberg, H. E.

1981-01-01

The subsynoptis-scale kinetic energy balance during the Red River Valley tornado outbreak is presented in order to diagnose storm environment interactions. Area-time averaged energetics indicate that horizontal flux convergence provides the major energy source to the region, while cross contour flow provides the greatest sink. Maximum energy variability is found in the upper levels in association with jet stream activity. Area averaged energetics at individual observation times show that the energy balance near times of maximum storm activity differs considerably from that of the remaining periods. The local kinetic energy balance over Oklahoma during the formation of a limited jet streak receives special attention. Cross contour production of energy is the dominant local source for jet development. Intense convection producing the Red River Valley tornadoes may have contributed to this local development by modifying the surrounding environment.

[Off-line control of runoff pollution by filtering ditch-pond system in urban tourist areas].

PubMed

Chen, Qing-Feng; Shan, Bao-Qing; Yin, Cheng-Qing; Hu, Cheng-Xiao

2007-10-01

An off-line filtering ditch-pond system for controlling storm runoff pollution in urban tourist areas was developed, which could retain the first flush effectively, resulting in the decrease of pollutant concentration and suspended solid average grain size, and the improvement of pollutant retention in runoff. This system could be an effective treatment system for storm runoff pollution, particularly for the scarcity of available land use in urban areas. In 2005, the yearly retention rates of TSS, COD, TN and TP were 86.4%, 85.5%, 83.9% and 82.9%, and during a storm event on June 26, the retention rates of runoff volume, TSS, COD, TN and TP were 67.9%, 97.0%, 89.2%, 94.9% and 96.2%, respectively. This system could also retain most of the suspended solids in runoff.

In situ measurements and radar observations of a severe storm - Electricity, kinematics, and precipitation

NASA Technical Reports Server (NTRS)

Byrne, G. J.; Few, A. A.; Stewart, M. F.; Conrad, A. C.; Torczon, R. L.

1987-01-01

Electric field measurements made inside a multicell severe storm in Oklahoma in 1983 with a balloon-borne instrument are presented. The properties of the electric charge regions, such as altitude, thickness, and charge concentrations, are studied. These measurements are analzyed with meteorological measurements of temperature and humidity, and balloon tracking and radar observations. The relation between the electric charge structure and the precipitation and kinematic features of the storm is examined. The data reveal that the cell exhibits a bipolar charge structure with negative charge below positive charge. The average charge concentrations of the two regions are estimated as -1.2 and 0.15 nC/cu m, respectively; the upper positive charge is about 6 km in vertical extent, and the lower negative charge is less than 1 km in vertical extent.

Using Satellite Imagery to Quantify Water Quality Impacts and Recovery from Hurricane Harvey

NASA Astrophysics Data System (ADS)

Sobel, R. S.; Kiaghadi, A.; Rifai, H. S.

2017-12-01

Record rainfall during Hurricane Harvey in the Houston-Galveston region generated record flows containing suspended sediment that was likely contaminated. Conventional water quality monitoring requires resource intensive field campaigns, and produces sparse datasets. In this study, satellite data were used to quantify suspended sediment (TSS) concentrations and mass within the region's estuary system and to estimate sediment deposition and transport. A conservative two band, red-green empirical regression was developed from the Sentinel 2 satellite to calculate TSS concentrations and masses. The regression was calibrated with an R2 = 0.73 (n=28) and validated with an R2 = 0.75 (n=12) using 2016 & 2017 imagery. TSS concentrations four days, 14 days, and 44 days post-storm were compared with a reference condition three days before storm arrival. Results indicated that TSS concentrations were an average of 100% higher four days post-storm, and 150% higher after 14 days, however, the average concentration on day 144 was only seven percent higher than the reference condition, suggesting the estuary system is approaching recovery to pre-storm conditions. Sediment masses were determined from the regressed concentrations and water volumes estimated from a bottom elevation grid combined with water surface elevations observed coincidently with the satellite image. While water volumes were only 13% higher on both day four and day 14 post-storm; sediment masses were 195% and 227% higher than the reference condition, respectively. By day 44, estuary sediment mass returned to just 2.9% above the reference load. From a mechanistic standpoint, the elevated TSS concentrations on day four indicated an advection-based regime due to stormwater runoff draining through the estuarine system. Sometime, however, between days 14 and 44, transport conditions switched from advection-dominated to deposition-driven as indicated by the near normal TSS concentrations on day 44.

Determination of effective droplet radius and optical depth of liquid water clouds over a tropical site in northern Thailand using passive microwave soundings, aircraft measurements and spectral irradiance data

NASA Astrophysics Data System (ADS)

Nimnuan, P.; Janjai, S.; Nunez, M.; Pratummasoot, N.; Buntoung, S.; Charuchittipan, D.; Chanyatham, T.; Chantraket, P.; Tantiplubthong, N.

2017-08-01

This paper presents an algorithm for deriving the effective droplet radius and optical depth of liquid water clouds using ground-based measurements, aircraft observations and an adiabatic model of cloud liquid water. The algorithm derives cloud effective radius and cloud optical depth over a tropical site at Omkoi (17.80°N, 98.43°E), Thailand. Monthly averages of cloud optical depth are highest in April (54.5), which is the month with the lowest average cloud effective radius (4.2 μm), both occurring before the start of the rainy season and at the end of the high contamination period. By contrast, the monsoon period extending from May to October brings higher cloud effective radius and lower cloud optical depth to the region on average. At the diurnal scale there is a gradual increase in average cloud optical depth and decrease in cloud effective radius as the day progresses.

XBeach and CSHORE Numerical Model Assessment of the Beach and Foredune Morphodynamic Response of a Barrier Island during Hurricane Storm Surge Inundation - Folletts Island Case Study

NASA Astrophysics Data System (ADS)

Figlus, J.

2016-02-01

More than 400 barrier islands line the United States coasts providing a first line of defense against surge and wave attack during extreme storm events. While some pre- and post-storm topography and bathymetry data of barrier islands inundated during a storm exist, very little information is available to help understand the complex hydrodynamic and morphodynamic processes during storm impact. These processes are crucial to understanding sediment budgets, potential threats to infrastructure and best coastal management practices for specific locations. Follett's Island (FI) is a low-lying sediment-starved barrier island located on the Upper Texas Coast, a stretch of coastline along the Gulf of Mexico experiencing on average four hurricanes and four tropical cyclones per decade. During Hurricane Ike, water levels and wave heights at FI exceeded the 100-year and 40-year return values, respectively. This caused the island to undergo a sequence of four distinct interaction regimes, including impact, overtopping, inundation, and storm surge ebb. Each regime caused unique morphology changes to the island. The physical processes governing the real-time morphodynamic response of the beach and dune system during 96 hours of hurricane impact were modeled using XBeach (2D) and CSHORE (1D). Hydrodynamic boundary conditions were obtained from ADCIRC/SWAN model runs validated with measured buoy and wave gauge data while LiDAR surveys provided pre- and post-storm measured topography. XBeach displayed a decent model skill and was very useful in qualitatively visualizing erosion and deposition patterns during each regime. CSHORE also displayed a decent model skill and was able to accurately predict the post-storm beach slope and shoreline, but was less effective at simulating the foredune morphology. Modeling results show that the complete morphodynamic response of FI to Hurricane Ike was far more complex than suggested by only before and after storm topography surveys.

Sediment accretion and organic carbon burial relative to sea-level rise and storm events in two mangrove forests in Everglades National Park

USGS Publications Warehouse

Smoak, Joseph M.; Breithaupt, Joshua L.; Smith, Thomas J.; Sanders, Christian J.

2013-01-01

The goal of this investigation was to examine how sediment accretion and organic carbon (OC) burial rates in mangrove forests respond to climate change. Specifically, will the accretion rates keep pace with sea-level rise, and what is the source and fate of OC in the system? Mass accumulation, accretion and OC burial rates were determined via 210Pb dating (i.e. 100 year time scale) on sediment cores collected from two mangrove forest sites within Everglades National Park, Florida (USA). Enhanced mass accumulation, accretion and OC burial rates were found in an upper layer that corresponded to a well-documented storm surge deposit. Accretion rates were 5.9 and 6.5 mm yr−1 within the storm deposit compared to overall rates of 2.5 and 3.6 mm yr−1. These rates were found to be matching or exceeding average sea-level rise reported for Key West, Florida. Organic carbon burial rates were 260 and 393 g m−2 yr−1 within the storm deposit compared to 151 and 168 g m−2 yr−1 overall burial rates. The overall rates are similar to global estimates for OC burial in marine wetlands. With tropical storms being a frequent occurrence in this region the resulting storm surge deposits are an important mechanism for maintaining both overall accretion and OC burial rates. Enhanced OC burial rates within the storm deposit could be due to an increase in productivity created from higher concentrations of phosphorus within storm-delivered sediments and/or from the deposition of allochthonous OC. Climate change-amplified storms and sea-level rise could damage mangrove forests, exposing previously buried OC to oxidation and contribute to increasing atmospheric CO2 concentrations. However, the processes described here provide a mechanism whereby oxidation of OC would be limited and the overall OC reservoir maintained within the mangrove forest sediments.

Storm track response to climate change: Insights from simulations using an idealized dry GCM.

NASA Astrophysics Data System (ADS)

Mbengue, Cheikh; Schneider, Tapio

2013-04-01

The midlatitude storm tracks, where the most intense extratropical cyclones are found, are an important fixture in the general circulation. They are instrumental in balancing the Earth's heat, momentum, and moisture budgets and are responsible for the weather and climatic patterns over large regions of the Earth's surface. As a result, the midlatitude storm tracks are the subject of a considerable amount of scientific research to understand their response to global warming. This has produced the robust result showing that the storm tracks migrate poleward with global warming. However, the dynamical mechanisms responsible for this migration remain unclear. Our work seeks to broaden understanding of the dynamical mechanisms responsible for storm track migration. Competing mechanisms present in the comprehensive climate models often used to study storm track dynamics make it difficult to determine the primary mechanisms responsible for storm track migration. We are thus prompted to study storm track dynamics from a simplified and idealized framework, which enables the decoupling of mean temperature effects from the effects of static stability and of tropical from extratropical effects. Using a statistically zonally symmetric, dry general circulation model (GCM), we conduct a series of numerical simulations to help understand the storm track response to global mean temperatures and to the tropical convective static stability, which we can vary independently. We define storm tracks as regions of zonally and temporally averaged maxima of barotropic eddy kinetic energy (EKE). This storm track definition also allows us to use previously found scalings between the magnitude of bulk measures of mean available potential energy (MAPE) and EKE, to decompose MAPE, and to obtain some mechanistic understanding of the storm track response in our simulations. These simulations provide several insights, which enable us to extend upon existing theories on the mechanisms driving the poleward migration of the storm tracks. We demonstrate a poleward migration of the midlatitude storm tracks in dry atmospheres with fixed pole-equator temperature contrast and increasing radiative equilibrium mean temperature, without changes in convective static stability. We also show scalings between the location of maxima of surface MAPE and of barotropic EKE. In the simulations where we independently vary tropical convective static stability, we find a marked poleward migration of the storm tracks. However, our decomposition shows that meridional temperature gradients, and not static stability, determine the location and the intensity of the storm tracks. This suggests that although the storm tracks are sensitive to tropical convective static stability, it influences them indirectly. Furthermore, our simulations show that the storm tracks generally migrate in tandem with the terminus of the Hadley cell. Therefore, we hypothesize that it is possible that the Hadley cell provides the tropical-extratropical communication necessary to generate the storm track response to tropical convective static stability we observe in the simulations. The results contained herein could be used to supplement ongoing storm track research in moist atmospheres using comparatively more comprehensive GCMs to understand storm track dynamics in earth-like environments.

The Historical Context of the 2017 Hurricane Season's Ocean Warmth

NASA Astrophysics Data System (ADS)

Jacobs, P.; Akella, S.; Trenberth, K. E.; Lijing, C.; Abraham, J. P.

2017-12-01

Public discussion of the unusually active 2017 North Atlantic Hurricane Season quickly focused on the role of sea surface temperatures (SSTs) in the North Atlantic. Some meteorologists characterized them as near-normal, while climate-focused voices tended to characterize them as warmer than average, placing them in the context of anthropogenic warming. Much of this divergence in views can be explained by the relatively recent, relatively warm baseline (1981-2010) used for daily SST information, such as provided by OISSTv2. Longer term records of SSTs, such as HadISST, HadSST, and ERSST only attempt to provide monthly averages, while tropical cyclones have lifetimes on the timescale of days. Further, hurricanes create a cold wake which can impact storm movement and intensity, as well as subsequent storms, but is gradually wiped out by the sun. This process is further complicated by the role of ocean heat content (OHC), an increase in which can mitigate the impact of upwelled water. Here we examine the statistical characteristics of daily SSTs and OHC during the satellite record, including their temporal autocorrelation, and use this information in conjunction with longer term monthly records to bound what we can and cannot confidently say about the longer term historical context of the storms Harvey, Irma, and Maria.

U.S. Geological Survey Catskill/Delaware Water-Quality Network: Water-Quality Report Water Year 2006

USGS Publications Warehouse

McHale, Michael R.; Siemion, Jason

2010-01-01

The U.S. Geological Survey operates a 60-station streamgaging network in the New York City Catskill/Delaware Water Supply System. Water-quality samples were collected at 13 of the stations in the Catskill/Delaware streamgaging network to provide resource managers with water-quality and water-quantity data from the water-supply system that supplies about 85 percent of the water needed by the more than 9 million residents of New York City. This report summarizes water-quality data collected at those 13 stations plus one additional station operated as a part of the U.S. Environmental Protection Agency's Regional Long-Term Monitoring Network for the 2006 water year (October 1, 2005 to September 30, 2006). An average of 62 water-quality samples were collected at each station during the 2006 water year, including grab samples collected every other week and storm samples collected with automated samplers. On average, 8 storms were sampled at each station during the 2006 water year. The 2006 calendar year was the second warmest on record and the summer of 2006 was the wettest on record for the northeastern United States. A large storm on June 26-28, 2006, caused extensive flooding in the western part of the network where record peak flows were measured at several watersheds.

Characteristics of peak streamflows and extent of inundation in areas of West Virginia and southwestern Virginia affected by flooding, June 2016

USGS Publications Warehouse

Austin, Samuel H.; Watson, Kara M.; Lotspeich, R. Russell; Cauller, Stephen J.; White , Jeremy S.; Wicklein, Shaun M.

2017-11-17

Heavy rainfall occurred across central and southern West Virginia in June 2016 as a result of repeated rounds of torrential thunderstorms. The storms caused major flooding and flash flooding in central and southern West Virginia with Kanawha, Fayette, Nicholas, and Greenbrier Counties among the hardest hit. Over the duration of the storms, from 8 to 9.37 inches of rain was reported in areas in Greenbrier County. Peak streamflows were the highest on record at 7 locations, and streamflows at 18 locations ranked in the top five for the period of record at U.S. Geological Survey streamflow-gaging stations used in this study. Following the storms, U.S. Geological Survey hydrographers identified and documented 422 high-water marks in West Virginia, noting location and height of the water above land surface. Many of these high-water marks were used to create flood-inundation maps for selected communities of West Virginia that experienced flooding in June 2016. Digital datasets of the inundation areas, mapping boundaries, and water depth rasters are available online.

Artificial magnetic field for the space station (Protecting space stations in future space missions)

NASA Astrophysics Data System (ADS)

Ahmadi Tara, Miss

Problem Explanation Strong solar storms and cosmic rays make great disturbances for equip-ment outside the magnetosphere. Also these disturbances are so harmful for biological process of living cells. If one decides to stay more outside the Earth, one's healthy is in a great danger. To investigate space station situation against strong solar storms, 5 recent strong solar storms have been selected. Dst of these storms are more than -300 nT. Each one of these storms has an accurate danger percentage. These data has been shown in Tab I. Tab I. strong solar storms during 1989-2003 and their danger percentage for space equipments and astronauts on outside the magnetic field As has been shown in Tab I. these strong storms are so dangerous and make problem for human outside the Earth layers. Basic on [13] solar activities in next century will be more than this century. That paper shows that the average number of sunspots in this century is less than 77 and this average will be more than 150 sunspots in a century. So we have only 70 years to prepare a suitable space station in other wise building this centre wills has many problem such as health security and long travels. Method explanation Only method to face with energetic particles is magnetic field. Space station is bereft of strong magnetic field to protect herself from energetic particles that released from the Sun and other types of stars in other galaxies (cosmic rays). Therefore the existence of an artificial magnetic field is necessary, this is not important that this field will be for the space station or its inner space because this field performs as magnetosphere. It does not allow energetic particles to enter the field. Also this field loads up to solar magnetic field as magnetosphere. Position of this artificial field is not important because basic on the simulations this field could repulse 85.6Modeling Important feature of this artificial field is its situation against solar magnetic field, i.e. these fields always are anti-aligned because artificial field could change direction by itself basic on the situation of Sun. Relationship between artificial field and solar storm has two types: 1) Artifi-cial field loads up to solar storm's magnetic field and makes magnetic reconnection 2) artificial field repulses energetic solar particles. These below equations show situation of artificial field against magnetic reconnection with magnetic field of solar storm and repulsing particles. Basic on the volume of repulsed particles the strength of field could be: Each one of these storms has an accurate danger percentage. These data has been shown in Tab I. Tab I. strong solar storms during 1989-2003 and their danger percentage for space equipments and astronauts on outside the magnetic field As has been shown in Tab I. these strong storms are so dangerous and make problem for human outside the Earth layers. Basic on [13] solar activities in next century will be more than this century. That paper shows that the average number of sunspots in this century is less than 77 and this average will be more than 150 sunspots in a century. So we have only 70 years to prepare a suitable space station in other wise building this centre wills has many problem such as health security and long travels. Method explanation Only method to face with energetic particles is magnetic field. Space station is bereft of strong magnetic field to protect herself from energetic particles that released from the Sun and other types of stars in other galaxies (cosmic rays). Therefore the existence of an artificial magnetic field is necessary, this is not important that this field will be for the space station or its inner space because this field performs as magnetosphere. It does not allow energetic particles to enter the field. Also this field loads up to solar magnetic field as magnetosphere. Position of this artificial field is not important because basic on the simulations this field could repulse 85.6Modeling Important feature of this artificial field is its situation against solar magnetic field, i.e. these fields always are anti-aligned because artificial field could change direction by itself basic on the situation of Sun. Relationship between artificial field and solar storm has two types: 1) Artificial field loads up to solar storm's magnetic field and makes magnetic reconnection 2) ar-tificial field repulses energetic solar particles. These below equations show situation of artificial field against magnetic reconnection with magnetic field of solar storm and repulsing particles. Basic on the volume of repulsed particles the strength of field could be: General equation of artificial field: Equations of artificial field basic on the magnetic reconnection: Also equation of balance of electrical energy is: That , V and P are denoting respectively density, velocity and pressure. is plasma energy density. J= current density, Bo =artificial magnetic field, B,E=plasma magnetic and electric field. Vs=volume of a sphere with r radius and =resistance General equation of artificial field: Equations of artificial field basic on the magnetic reconnec-tion: Also equation of balance of electrical energy is: That , V and P are denoting respectively density, velocity and pressure. is plasma energy density. J= current density, Bo =artificial magnetic field, B,E=plasma magnetic and electric field. Vs=volume of a sphere with r radius and =resistance Results Tab II. Danger percentage of 5 strong solar storms for equipment and astronauts in the future space station within the influence on artificial field As has been shown in Tab II artificial magnetic field could pass great dangers of solar storms and protect space station wherever of free space. FIG.2) Upper panel shows X-ray flux at two wavelengths 0.5-4 ˚ and 1-8 ˚. Lower Panel shows Proton flux in various energy levels received on the Moon's A A surface from solar storm 2000(obtained from simulation) 0-14(UT) obtained from outside the field, 14-7(UT) obtained from receiver in the field, 7-0(UT) obtained from receiver behind in-strument Conclusion In this brief paper, I describe a way to protect future space station from energetic particles. This field could reduce damage of solar storms and cosmic rays that arrived to the space station outside the Earth magnetic field. This field performs as magnetosphere for space station. It could change its situation and make easy live on the space station. This strong magnetic field must be generated by low-temperature superconductors. They are suit-able material to use at generating a strong magnetic field. These materials could be used in the structure of spacecrafts during long duration space travels in future

Loading of fecal indicator bacteria in North Carolina tidal creek headwaters: hydrographic patterns and terrestrial runoff relationships.

PubMed

Stumpf, Curtis H; Piehler, Michael F; Thompson, Suzanne; Noble, Rachel T

2010-09-01

In the New River Estuary (NRE) in eastern North Carolina (NC), fecal indicator bacteria (FIB) levels exceed water quality standards, leading to closure of estuarine waters for shellfishing and classification of parts of the estuary as "impaired" per the Clean Water Act section 303(d) list. As a means to investigate fecal contamination and loading of FIB to the NRE, a continuous automated sampler (ISCO) outfitted with flow modules and water quality probes was placed in four first-order tidal creek headwaters. Total storm discharge and bacterial load for Escherichia coli (EC) and Enterococcus spp. (ENT) were calculated using graphical volumetric flow calculations and interpolation of FIB measurements over each storm's duration for 10 storms. Mean total load of 10(9)-10(12) EC and ENT cells (MPN) occurred over the course of each storm. Total storm loading, averaged across all storms, was as much as 30 and 37 times greater than equivalent duration of baseflow loading for EC and ENT, respectively. Within the first 30% of creek storm volume for all storms and all creeks combined, a mean cumulative load of only 37% and 44% of the total EC and ENT cells, respectively, was discharged, indicating these creeks are not demonstrating a 'first flush' scenario for FIB. The median storm Event Mean Concentrations (EMCs) were 6.37 × 10(2) and 2.03 × 10(2) MPN/100 mL, for EC and ENT, respectively, compared with median baseflow concentrations of 1.48 × 10(2) and 4.84 × 10(1) for EC and ENT, respectively, and were significantly different between base and storm flow events. FIB was correlated with TSS (weak), flow rate (strong), and different stages (base, rising, peak, and falling) of the hydrograph (strong). Pollutographs indicate large intra-storm variability of FIB, and the need for more intensive sampling throughout a storm in order to attain accurate FIB contaminant estimates. Instream sediment concentrations ranged from 5 to 478 (MPN/g) and 13 to 776 (MPN/g) for EC and ENT, respectively, indicating sediment as a source, but a minor reservoir. This overall approach for calculating loading in headwater tidal creeks is detailed. Accurate loading characterization of FIB during storms and dry weather conditions, and understanding intra-storm FIB concentrations, is imperative for understanding patterns of water quality impairment, establishing management planning, and developing appropriate mitigation strategies. Copyright © 2010 Elsevier Ltd. All rights reserved.

Differences in generation of magnetic storms driven by magnetic clouds, ejecta, sheath region before ICME and CIR

NASA Astrophysics Data System (ADS)

Nikolaeva, Nadezhda; Yermolaev, Yuri; Lodkina, Irina

2016-07-01

We investigate the efficiency of main phase storm generation by different solar wind (SW) streams when using 12 functions coupling (FC) various interplanetary parameters with magnetospheric state. By using our Catalog of Solar Wind Phenomena [Yermolaev et al., 2009] created on the basis of the OMNI database for 1976-2000, we selected the magnetic storms with Dst ≤ -50 nT for which interplanetary sources were following: MC (10 storms); Ejecta (31 storms); Sheath (21 storms); CIRs (31magnetic storms). To compare the interplanetary drivers we estimate an efficiency of magnetic storm generation by type of solar wind stream with using 12 coupling functions. We obtained that in average Sheath has more large efficiency of the magnetic storm generation and MC has more low efficiency in agreement with our previous results which show that by using a modification of formula by Burton et al. [1975] for connection of interplanetary conditions with Dst and Dst* indices the efficiency of storm generation by Sheath and CIR was ~50% higher than generation by ICME [Nikolaeva et al., 2013; 2015]. The most part of FCs has sufficiently high correlation coefficients. In particular the highest values of coefficients (~ 0.5 up to 0.63) are observed for Sheath- driven storms. In a small part of FCs with low coefficients it is necessary to increase the number of magnetic storms to increase the statistical significance of results. The reliability of the obtained data and possible reasons of divergences for various FCs and various SW types require further researches. The authors are grateful for the opportunity to use the OMNI database. This work was supported by the Russian Foundation for Basic Research, project 16-02-00125, and by Program of Presidium of the Russian Academy of Sciences. References: Nikolaeva, N. S., Y. I. Yermolaev, and I. G. Lodkina (2013), Modeling of Dst-index temporal profile on the main phase of the magnetic storms generated by different types of solar wind, Cosmic Res., 51 (6), 401-412. Nikolaeva, N. S., Y. I. Yermolaev, and I. G. Lodkina (2015), Modeling of the corrected Dst* index temporal profile on the main phase of the magnetic storms generated by different types of solar wind, Cosmic Res., 53(2), 119-127. Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, 47(2), 81-94.

Ionospheric storms at geophysically-equivalent sites - Part 1: Storm-time patterns for sub-auroral ionospheres

NASA Astrophysics Data System (ADS)

Mendillo, M.; Narvaez, C.

2009-04-01

The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions), the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ~12° tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms. The ionosonde stations at Wallops Island (VA) and Hobart (Tasmania) have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2) spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964-1976), 206 geomagnetic storms occurred that had Ap≥30 or Kp≥5 for at least one day of the storm. Our analysis of average storm-time perturbations (percent deviations from the monthly means) showed a remarkable agreement at both sites under a variety of conditions. Yet, small differences do appear, and in systematic ways. We attempt to relate these to stresses imposed over a few days of a storm that mimic longer term morphology patterns occurring over seasonal and solar cycle time spans. Storm effects versus season point to possible mechanisms having hemispheric differences (as opposed to simply seasonal differences) in how solar wind energy is transmitted through the magnetosphere into the thermosphere-ionosphere system. Storm effects versus the strength of a geomagnetic storm may, similarly, be related to patterns seen during years of maximum versus minimum solar activity.

Combined effects of projected sea level rise, storm surge, and peak river flows on water levels in the Skagit Floodplain

USGS Publications Warehouse

Hamman, Josheph J; Hamlet, Alan F.; Fuller, Roger; Grossman, Eric E.

2016-01-01

Current understanding of the combined effects of sea level rise (SLR), storm surge, and changes in river flooding on near-coastal environments is very limited. This project uses a suite of numerical models to examine the combined effects of projected future climate change on flooding in the Skagit floodplain and estuary. Statistically and dynamically downscaled global climate model scenarios from the ECHAM-5 GCM were used as the climate forcings. Unregulated daily river flows were simulated using the VIC hydrology model, and regulated river flows were simulated using the SkagitSim reservoir operations model. Daily tidal anomalies (TA) were calculated using a regression approach based on ENSO and atmospheric pressure forcing simulated by the WRF regional climate model. A 2-D hydrodynamic model was used to estimate water surface elevations in the Skagit floodplain using resampled hourly hydrographs keyed to regulated daily flood flows produced by the reservoir simulation model, and tide predictions adjusted for SLR and TA. Combining peak annual TA with projected sea level rise, the historical (1970–1999) 100-yr peak high water level is exceeded essentially every year by the 2050s. The combination of projected sea level rise and larger floods by the 2080s yields both increased flood inundation area (+ 74%), and increased average water depth (+ 25 cm) in the Skagit floodplain during a 100-year flood. Adding sea level rise to the historical FEMA 100-year flood resulted in a 35% increase in inundation area by the 2040's, compared to a 57% increase when both SLR and projected changes in river flow were combined.

The influence of sea surface temperature on the intensity and associated storm surge of tropical cyclone Yasi: a sensitivity study

NASA Astrophysics Data System (ADS)

Lavender, Sally L.; Hoeke, Ron K.; Abbs, Deborah J.

2018-03-01

Tropical cyclones (TCs) result in widespread damage associated with strong winds, heavy rainfall and storm surge. TC Yasi was one of the most powerful TCs to impact the Queensland coast since records began. Prior to Yasi, the SSTs in the Coral Sea were higher than average by 1-2 °C, primarily due to the 2010/2011 La Niña event. In this study, a conceptually simple idealised sensitivity analysis is performed using a high-resolution regional model to gain insight into the influence of SST on the track, size, intensity and associated rainfall of TC Yasi. A set of nine simulations with uniform SST anomalies of between -4 and 4 °C applied to the observed SSTs are analysed. The resulting surface winds and pressure are used to force a barotropic storm surge model to examine the influence of SST on the associated storm surge of TC Yasi. An increase in SST results in an increase in intensity, precipitation and integrated kinetic energy of the storm; however, there is little influence on track prior to landfall. In addition to an increase in precipitation, there is a change in the spatial distribution of precipitation as the SST increases. Decreases in SSTs result in an increase in the radius of maximum winds due to an increase in the asymmetry of the storm, although the radius of gale-force winds decreases. These changes in the TC characteristics also lead to changes in the associated storm surge. Generally, cooler (warmer) SSTs lead to reduced (enhanced) maximum storm surges. However, the increase in surge reaches a maximum with an increase in SST of 2 °C. Any further increase in SST does not affect the maximum surge but the total area and duration of the simulated surge increases with increasing upper ocean temperatures. A large decrease in maximum storm surge height occurs when a negative SST anomaly is applied, suggesting if TC Yasi had occurred during non-La Niña conditions the associated storm surge may have been greatly diminished, with a decrease in storm surge height of over 3 m when the SST is reduced by 2 °C. In summary, increases in SST lead to an increase in the potential destructiveness of TCs with regard to intensity, precipitation and storm surge, although this relationship is not linear.

Coastal hazards in a changing world: projecting and communicating future coastal flood risk at the local-scale using the Coastal Storm Modeling System (CoSMoS)

NASA Astrophysics Data System (ADS)

O'Neill, Andrea; Barnard, Patrick; Erikson, Li; Foxgrover, Amy; Limber, Patrick; Vitousek, Sean; Fitzgibbon, Michael; Wood, Nathan

2017-04-01

The risk of coastal flooding will increase for many low-lying coastal regions as predominant contributions to flooding, including sea level, storm surge, wave setup, and storm-related fluvial discharge, are altered with climate change. Community leaders and local governments therefore look to science to provide insight into how climate change may affect their areas. Many studies of future coastal flooding vulnerability consider sea level and tides, but ignore other important factors that elevate flood levels during storm events, such as waves, surge, and discharge. Here we present a modelling approach that considers a broad range of relevant processes contributing to elevated storm water levels for open coast and embayment settings along the U.S. West Coast. Additionally, we present online tools for communicating community-relevant projected vulnerabilities. The Coastal Storm Modeling System (CoSMoS) is a numerical modeling system developed to predict coastal flooding due to both sea-level rise (SLR) and plausible 21st century storms for active-margin settings like the U.S. West Coast. CoSMoS applies a predominantly deterministic framework of multi-scale models encompassing large geographic scales (100s to 1000s of kilometers) to small-scale features (10s to 1000s of meters), resulting in flood extents that can be projected at a local resolution (2 meters). In the latest iteration of CoSMoS applied to Southern California, U.S., efforts were made to incorporate water level fluctuations in response to regional storm impacts, locally wind-generated waves, coastal river discharge, and decadal-scale shoreline and cliff changes. Coastal hazard projections are available in a user-friendly web-based tool (www.prbo.org/ocof), where users can view variations in flood extent, maximum flood depth, current speeds, and wave heights in response to a range of potential SLR and storm combinations, providing direct support to adaptation and management decisions. In order to capture the societal aspect of the hazard, projections are combined with socioeconomic exposure to produce clear, actionable information (https://www.usgs.gov/apps/hera/); this integrated approach to hazard displays provides an example of how to effectively translate complex climate impacts projections into simple, societally-relevant information.

A study of geomagnetic storms

NASA Technical Reports Server (NTRS)

Patel, V. L.

1975-01-01

Twenty-one geomagnetic storm events during 1966 and 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. When the Bz is already negative, its value becomes further negative. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onet. On the small-scale behavior of the magnetic field and electric field (E=-VxB) studied in details for the three events, it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. These fluctuations become larger just before the main phase of the storm begins. In the largescale behavior field remains quiet because the small scale variations are averaged out.

Interception loss, throughfall and stemflow in a maritime pine stand. II. An application of Gash's analytical model of interception

NASA Astrophysics Data System (ADS)

Loustau, D.; Berbigier, P.; Granier, A.

1992-10-01

Interception, throughfall and stemflow were determined in an 18-year-old maritime pine stand for a period of 30 months. This involved 71 rainfall events, each corresponding either to a single storm or to several storms. Gash's analytical model of interception was used to estimate the sensitivity of interception to canopy structure and climatic parameters. The seasonal cumulative interception loss corresponded to 12.6-21.0% of the amount of rainfall, whereas throughfall and stemflow accounted for 77-83% and 1-6%, respectively. On a seasonal basis, simulated data fitted the measured data satisfactorily ( r2 = 0.75). The rainfall partitioning between interception, throughfall and stemflow was shown to be sensitive to (1) the rainfall regime, i.e. the relative importance of light storms to total rainfall, (2) the climatic parameters, rainfall rate and average evaporation rate during storms, and (3) the canopy structure parameters of the model. The low interception rate of the canopy was attributed primarily to the low leaf area index of the stand.

Sediment concentrations and loads in the Loxahatchee River estuary, Florida, 1980-82

USGS Publications Warehouse

Sonntag, Wayne H.; McPherson, Benjamin F.

1984-01-01

This study was conducted to estimate the magnitude of sediment loads and the general spatial and temporal patterns of sediment transport in the Loxahatchee River estuary, Florida. Mean concentrations of suspended sediment generally were higher in the Jupiter Inlet area than in the remainder of the embayment area. Concentrations of suspended sediment varied with season and weather conditions. Concentrations in selected tributaries following Tropical Storm Dennis in August 1981 immediately increased as much as 16 times over concentrations before the storm. Suspended-sediment loads from the tributaries were also highly seasonal and storm related. During a 61-day period of above-average rainfall that included Tropical Storm Dennis, 5 major tributaries discharged 926 tons (short) of suspended sediment to the estuary, accounting for 74 percent of the input for the 1981 water year and 49 percent of the input for the 20-month study period. Suspended-sediment loads at Jupiter Inlet and at the mouth of the estuary embayment on both incoming and outgoing tides far exceeded tributary loads, but the direction of long-term, net tidal transport was not determined. (USGS)

Tropical Cyclone Evolution and Water and Energy Fluxes: A Hurricane Katrina Case Study

NASA Astrophysics Data System (ADS)

Pinheiro, M. C.; Zhou, Y.

2015-12-01

Tropical cyclones are a highly destructive force of nature, characterized by extreme precipitation levels and wind speeds and heavy flooding. There are concerns that climate change will cause changes in the intensity and frequency of tropical cyclones. Therefore, the quantification of the water and energy fluxes that occur during a tropical cyclone's life cycle are important for anticipating the magnitude of damages that are likely to occur. This study used HURDAT2 storm track information and data from the satellite-derived SeaFlux and TRMM products to determine changes in precipitation, wind, and latent and sensible heat throughout the life cycle of Hurricane Katrina. The variables were examined along and around the storm track, taking averages both at stationary 5x5 degree boxes and within the instantaneous hurricane domain. Analysis focused on contributions of convergence and latent heat to the storm evolution and examined how the total flux was related to the storm intensity. Certain features, such as the eye, were not resolved due to the data resolution, but the data captures the general trend of enhanced flux levels that are due to the storm's presence. Analysis also included examination of the water and energy budgets as related to convergence and the sensible and latent heat fluxes.

Retrieving Storm Electric Fields From Aircraft Field Mill Data. Part 2; Applications

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Mach, D. M.; Christian, H. J.; Stewart, M. F.; Bateman, M. G.

2005-01-01

The Lagrange multiplier theory and "pitch down method" developed in Part I of this study are applied to complete the calibration of a Citation aircraft that is instrumented with six field mill sensors. When side constraints related to average fields are used, the method performs well in computer simulations. For mill measurement errors of 1 V/m and a 5 V/m error in the mean fair weather field function, the 3-D storm electric field is retrieved to within an error of about 12%. A side constraint that involves estimating the detailed structure of the fair weather field was also tested using computer simulations. For mill measurement errors of 1 V/m, the method retrieves the 3-D storm field to within an error of about 8% if the fair weather field estimate is typically within 1 V/m of the true fair weather field. Using this side constraint and data from fair weather field maneuvers taken on 29 June 2001, the Citation aircraft was calibrated. The resulting calibration matrix was then used to retrieve storm electric fields during a Citation flight on 2 June 2001. The storm field results are encouraging and agree favorably with the results obtained from earlier calibration analyses that were based on iterative techniques.

Observations of storm morphodynamics using Coastal Lidar and Radar Imaging System (CLARIS): Importance of wave refraction and dissipation over complex surf-zone morphology at a shoreline erosional hotspot

NASA Astrophysics Data System (ADS)

Brodie, Katherine L.

Elevated water levels and large waves during storms cause beach erosion, overwash, and coastal flooding, particularly along barrier island coastlines. While predictions of storm tracks have greatly improved over the last decade, predictions of maximum water levels and variations in the extent of damage along a coastline need improvement. In particular, physics based models still cannot explain why some regions along a relatively straight coastline may experience significant erosion and overwash during a storm, while nearby locations remain seemingly unchanged. Correct predictions of both the timing of erosion and variations in the magnitude of erosion along the coast will be useful to both emergency managers and homeowners preparing for an approaching storm. Unfortunately, research on the impact of a storm to the beach has mainly been derived from "pre" and "post" storm surveys of beach topography and nearshore bathymetry during calm conditions. This has created a lack of data during storms from which to ground-truth model predictions and test hypotheses that explain variations in erosion along a coastline. We have developed Coastal Lidar and Radar Imaging System (CLARIS), a mobile system that combines a terrestrial scanning laser and an X-band marine radar system using precise motion and location information. CLARIS can operate during storms, measuring beach topography, nearshore bathymetry (from radar-derived wave speed measurements), surf-zone wave parameters, and maximum water levels remotely. In this dissertation, we present details on the development, design, and testing of CLARIS and then use CLARIS to observe a 10 km section of coastline in Kitty Hawk and Kill Devil Hills on the Outer Banks of North Carolina every 12 hours during a Nor'Easter (peak wave height in 8 m of water depth = 3.4 m). High decadal rates of shoreline change as well as heightened erosion during storms have previously been documented to occur within the field site. In addition, complex bathymetric features that traverse the surf-zone into the nearshore are present along the southern six kilometers of the field site. In addition to the CLARIS observations, we model wave propagation over the complex nearshore bathymetry for the same storm event. Data reveal that the complex nearshore bathymetry is mirrored by kilometer scale undulations in the shoreline, and that both morphologies persist during storms, contrary to common observations of shoreline and surf-zone linearization by large storm waves. We hypothesize that wave refraction over the complex nearshore bathymetry forces flow patterns which may enhance or stabilize the shoreline and surf-zone morphology during storms. In addition, our semi-daily surveys of the beach indicate that spatial and temporal patterns of erosion are strongly correlated to the steepness of the waves. Along more than half the study site, fifty percent or more of the erosion that occurred during the first 12 hours of the storm was recovered within 24 hours of the peak of the storm as waves remained large (>2.5 m), but transitioned to long period swell. In addition, spatial variations in the amount of beach volume change during the building portion of the storm were strongly correlated with observed wave dissipation within the inner surf zone, as opposed to predicted inundation elevations or alongshore variations in wave height.

Looking inside out: tracing internal moisture and salinity changes in dunes on the west coast of Ireland

NASA Astrophysics Data System (ADS)

Nash, Ciaran; Bourke, Mary

2017-04-01

Coastal sand dune systems are some of the most physically dynamic landscapes; their susceptibility to geomorphic change is rooted in a host of interconnected processes and feedbacks. Soil moisture and salinity are two fundamental environmental variables capable of exerting a geomorphic influence but have not been thoroughly investigated in coastal dunes. In northwest Europe, coastal dunes are predominantly sediment-limited systems with reduced capacities to avoid severe morphological changes arising from storms. Climatic changes over the next century are predicted to manifest in more frequent and intense storms with the potential to enact severe geomorphic change in coastal settings. A lack of data pertaining to internal dune hydrosaline dynamics suggests we are missing part of the bigger picture. We conducted a pilot study of moisture and salinity dynamics within the upper 50 cm of the vadose zone in a vegetated dune system at Golden Strand, Achill Island on the west coast of Ireland. Golden Strand is a roughly 800 m long embayed sandy beach, backed by vegetated dunes that protect a low-lying machair grassland. A study transect was established across this dune-machair system, perpendicular to the shore. Innovative instrumentation in the form of capacitance probes and internal dune thermochrons were deployed to sample at 10 cm depth intervals at a sampling rate of 10 minutes and coupled with on-site rainfall data. Results indicate that dune moisture tracks rainfall inputs up to 30 cm depth. Antecedent moisture at depth was found to influence infiltration of water through the dune profile. Salinity within the study transect decreased with distance from the beach, suggesting that salt spray is the primary salt delivery mechanism in the dune system. We also noted that moisture and salinity below 30 cm depth failed to respond to rainfall events of varying intensities. Relatively constant moisture and salinity were observed at all depths within the machair. Predictions of climatic change for Ireland suggest more intense short-period precipitation events, this may increase infiltration depth. Baseline data collected will prove informative in predicting the response of Irish coastal dunes via changes in vegetation and dune stability.

Snow depth on Arctic sea ice from historical in situ data

NASA Astrophysics Data System (ADS)

Shalina, Elena V.; Sandven, Stein

2018-06-01

The snow data from the Soviet airborne expeditions Sever in the Arctic collected over several decades in March, April and May have been analyzed in this study. The Sever data included more measurements and covered a much wider area, particularly in the Eurasian marginal seas (Kara Sea, Laptev Sea, East Siberian Sea and Chukchi Sea), compared to the Soviet North Pole drifting stations. The latter collected data mainly in the central part of the Arctic Basin. The following snow parameters have been analyzed: average snow depth on the level ice (undisturbed snow) height and area of sastrugi, depth of snow dunes attached to ice ridges and depth of snow on hummocks. In the 1970s-1980s, in the central Arctic, the average depth of undisturbed snow was 21.2 cm, the depth of sastrugi (that occupied about 30 % of the ice surface) was 36.2 cm and the average depth of snow near hummocks and ridges was about 65 cm. For the marginal seas, the average depth of undisturbed snow on the level ice varied from 9.8 cm in the Laptev Sea to 15.3 cm in the East Siberian Sea, which had a larger fraction of multiyear ice. In the marginal seas the spatial variability of snow depth was characterized by standard deviation varying between 66 and 100 %. The average height of sastrugi varied from 23 cm to about 32 cm with standard deviation between 50 and 56 %. The average area covered by sastrugi in the marginal seas was estimated to be 36.5 % of the total ice area where sastrugi were observed. The main result of the study is a new snow depth climatology for the late winter using data from both the Sever expeditions and the North Pole drifting stations. The snow load on the ice observed by Sever expeditions has been described as a combination of the depth of undisturbed snow on the level ice and snow depth of sastrugi weighted in proportion to the sastrugi area. The height of snow accumulated near the ice ridges was not included in the calculations because there are no estimates of the area covered by those features from the Sever expeditions. The effect of not including that data can lead to some underestimation of the average snow depth. The new climatology refines the description of snow depth in the central Arctic compared to the results by Warren et al. (1999) and provides additional detailed data in the marginal seas. The snow depth climatology is based on 94 % Sever data and 6 % North Pole data. The new climatology shows lower snow depth in the central Arctic comparing to Warren climatology and more detailed data in the Eurasian seas.

The Early-Warning System for incoming storm surge and tide in the Republic of Mauritius

NASA Astrophysics Data System (ADS)

Bogaard, Tom; de Lima Rego, Joao; Vatvani, Deepak; Virasami, Renganaden; Verlaan, Martin

2016-04-01

The Republic of Mauritius (ROM) is a group of islands in the South West of the Indian Ocean, consisting of the main islands of Mauritius, Rodrigues and Agalega and the archipelago of Saint Brandon. The ROM is particularly vulnerable to the adverse effects of climate change, especially in the coastal zone, where a convergence of accelerating sea level rise and increasing intensity of tropical cyclones is expected to result in considerable economic loss, humanitarian stresses, and environmental degradation. Storm surges and swell waves are expected to be aggravated through sea level rise and climate change effects on weather patterns. Adaptation to increased vulnerability requires a re-evaluation of existing preparedness measures. The focus of this project is on more effective preparedness and issuing of alerts developing a fully-automated Early-Warning System for incoming storm surge and tide, together with the Mauritius Meteorological Services and the National Disaster Risk Reduction and Management Centre (NDRRMC), such that coastal communities in Mauritius, Rodrigues and Agalega Islands are able to evacuate timely and safely in case of predicted extreme water levels. The Mauritius Early-Warning System for storm surge and tide was implemented using software from Deltares' Open-Source and free software Community. A set of five depth-averaged Delft3D-FLOW hydrodynamic models are run every six-hours with a forecast horizon of three days, simulating water levels along the coast of the three main islands. Two regional models of horizontal resolution 5km force the three detailed models of 500m resolution; all models are forced at the surface by the 0.25° NOAA/GFS meteorological forecasts. In addition, our Wind-Enhancement Scheme is used to blend detailed cyclone track bulletin's info with the larger-scale Numerical Weather Predictions. Measured data is retrieved near real-time from available Automatic Weather Stations. All these workflows are managed by the operational platform software, Delft-FEWS. The presently operational Mauritius Early-Warning System produces a set of intuitive tables for each island, containing time- and space-varying information on threshold crossings by predicted water levels. At multiple locations for each island of the ROM, the operator is informed in one glance about the recommended preparedness level, from "Safe" to "Watch", "Alert" or "Warning" based on water level forecasts. The HTML page was designed together with the MMS and the NDRRMC, in order to be easy to interpret and disseminate by local authorities.

Efficacy of methoprene for mosquito control in storm water catch basins

USGS Publications Warehouse

Butler, M.; LeBrun, R.A.; Ginsberg, H.S.; Gettman, A.D.

2006-01-01

This study evaluated the efficacy of methoprene, a widely used juvenile hormone mimic, formulated as 30-day slow release Altosid? pellets, at controlling mosquitoes in underground storm water drainage catch basins. Data from applications to ?-sized cement catch basins in the laboratory, field observations from treated and untreated basins, and an experiment that confined mosquito larvae in floating emergence jars in catch basins showed that methoprene effectively controlled mosquitoes for a month under field conditions and substantially longer under laboratory conditions when applied at a dose of 3.5 g pellets per average-sized catch basin.

Hydrologic conditions controlling runoff generation immediately after wildfire

USGS Publications Warehouse

Ebel, Brian A.; Moody, John A.; Martin, Deborah A.

2012-01-01

We investigated the control of postwildfire runoff by physical and hydraulic properties of soil, hydrologic states, and an ash layer immediately following wildfire. The field site is within the area burned by the 2010 Fourmile Canyon Fire in Colorado, USA. Physical and hydraulic property characterization included ash thickness, particle size distribution, hydraulic conductivity, and soil water retention curves. Soil water content and matric potential were measured indirectly at several depths below the soil surface to document hydrologic states underneath the ash layer in the unsaturated zone, whereas precipitation and surface runoff were measured directly. Measurements of soil water content showed that almost no water infiltrated below the ash layer into the near-surface soil in the burned site at the storm time scale (i.e., minutes to hours). Runoff generation processes were controlled by and highly sensitive to ash thickness and ash hydraulic properties. The ash layer stored from 97% to 99% of rainfall, which was critical for reducing runoff amounts. The hydrologic response to two rain storms with different rainfall amounts, rainfall intensity, and durations, only ten days apart, indicated that runoff generation was predominantly by the saturation-excess mechanism perched at the ash-soil interface during the first storm and predominantly by the infiltration-excess mechanism at the ash surface during the second storm. Contributing area was not static for the two storms and was 4% (saturation excess) to 68% (infiltration excess) of the catchment area. Our results showed the importance of including hydrologic conditions and hydraulic properties of the ash layer in postwildfire runoff generation models.

Using SMAP to identify structural errors in hydrologic models

NASA Astrophysics Data System (ADS)

Crow, W. T.; Reichle, R. H.; Chen, F.; Xia, Y.; Liu, Q.

2017-12-01

Despite decades of effort, and the development of progressively more complex models, there continues to be underlying uncertainty regarding the representation of basic water and energy balance processes in land surface models. Soil moisture occupies a central conceptual position between atmosphere forcing of the land surface and resulting surface water fluxes. As such, direct observations of soil moisture are potentially of great value for identifying and correcting fundamental structural problems affecting these models. However, to date, this potential has not yet been realized using satellite-based retrieval products. Using soil moisture data sets produced by the NASA Soil Moisture Active/Passive mission, this presentation will explore the use of the remotely-sensed soil moisture data products as a constraint to reject certain types of surface runoff parameterizations within a land surface model. Results will demonstrate that the precision of the SMAP Level 4 Surface and Root-Zone soil moisture product allows for the robust sampling of correlation statistics describing the true strength of the relationship between pre-storm soil moisture and subsequent storm-scale runoff efficiency (i.e., total storm flow divided by total rainfall both in units of depth). For a set of 16 basins located in the South-Central United States, we will use these sampled correlations to demonstrate that so-called "infiltration-excess" runoff parameterizations under predict the importance of pre-storm soil moisture for determining storm-scale runoff efficiency. To conclude, we will discuss prospects for leveraging this insight to improve short-term hydrologic forecasting and additional avenues for SMAP soil moisture products to provide process-level insight for hydrologic modelers.

Modelling the 2013 Typhoon Haiyan storm surge: Effect of waves, offshore winds, tide phase, and translation speed

NASA Astrophysics Data System (ADS)

Bilgera, P. H. T.

2015-12-01

Super Typhoon Haiyan, with wind speeds exceeding 300 km h-1 (160 knots) generated a storm surge in San Pedro Bay reaching heights of more than 6m in Tacloban City. Delft Dashboard (DDB), an open-source standalone Matlab based graphical user interface linked to the FLOW and WAVE modeling software of Deltares, was used to develop a coupled flow and wave storm surge model to understand the Typhoon Haiyan storm surge development and propagation. Various experiments were designed to determine the effect of waves, the occurrence of offshore winds prior to the surge, tidal phase, and typhoon translation speed on the surge height. Wave coupling decreased the surge height by about 0.5m probably due to energy dissipation from white capping, bottom friction, and depth-induced breaking. Offshore-directed winds before the arrival of the storm eye resulted to receding of the water level in San Pedro and Cancabato Bay, corroborated by eyewitness and tide gauge data. The experiment wherein the offshore winds were removed resulted to no water receding and a surge with a smaller and gentler surge front, pointing to the importance of the initial water level drawdown in contributing to the destructive power of the wave front. With regard to tides, the effect in Tacloban was actually neither linear nor additive to the surge, with higher surge coincident to low tides and lower surge coincident to high tides. Lastly, the model run with typhoon having a slower translation speed than Haiyan was found to generate higher surges.

Characterization and statistical modeling of bacterial (Escherichia coli) outflows from watersheds that discharge into Southern Lake Michigan

USGS Publications Warehouse

Olyphant, G.A.; Thomas, Joan; Whitman, R.L.; Harper, D.

2003-01-01

Two watersheds in northwestern Indiana were selected for detailed monitoring of bacterially contaminated discharges (Escherichia coli) into Lake Michigan. A large watershed that drains an urbanized area with treatment plants that release raw sewage during storms discharges into Lake Michigan at the outlet of Burns Ditch. A small watershed drains part of the Great Marsh, a wetland complex that has been disrupted by ditching and limited residential development, at the outlet of Derby Ditch. Monitoring at the outlet of Burns Ditch in 1999 and 2000 indicated that E. coli concentrations vary over two orders of magnitude during storms. During one storm, sewage overflows caused concentrations to increase to more than 10,000 cfu/100 mL for several hours. Monitoring at Derby Ditch from 1997 to 2000 also indicated that E. coli concentrations increase during storms with the highest concentrations generally occurring during rising streamflow. Multiple regression analysis indicated that 60% of the variability in measured outflows of E. coli from Derby Ditch (n = 88) could be accounted for by a model that utilizes continuously measured rainfall, stream discharge, soil temperature and depth to water table in the Great Marsh. A similar analysis indicated that 90% of the variability in measured E. coli concentrations at the outlet of Burns Ditch (n = 43) during storms could be accounted for by a combination of continuously measured water-quality variables including nitrate and ammonium. These models, which utilize data that can be collected on a real-time basis, could form part of an Early Warning System for predicting beach closures.

Modelling the 2013 Typhoon Haiyan Storm Surge: Effect of Waves, Offshore Winds, Tide Phase, and Translation Speed

NASA Astrophysics Data System (ADS)

Bilgera, P. H. T.; Villanoy, C.; Cabrera, O.

2016-02-01

Super Typhoon Haiyan, with wind speeds exceeding 300 km h-1 (160 knots) generated a storm surge in San Pedro Bay reaching heights of more than 6m in Tacloban City. Delft Dashboard (DDB), an open-source standalone Matlab based graphical user interface linked to the FLOW and WAVE modeling software of Deltares, was used to develop a coupled flow and wave storm surge model to understand the Typhoon Haiyan storm surge development and propagation. Various experiments were designed to determine the effect of waves, the occurrence of offshore winds prior to the surge, tidal phase, and typhoon translation speed on the surge height. Wave coupling decreased the surge height by about 0.5m probably due to energy dissipation from white capping, bottom friction, and depth-induced breaking. Offshore-directed winds before the arrival of the storm eye resulted to receding of the water level in San Pedro and Cancabato Bay, corroborated by eyewitness and tide gauge data. The experiment wherein the offshore winds were removed resulted to no water receding and a surge with a smaller and gentler surge front, pointing to the importance of the initial water level drawdown in contributing to the destructive power of the wave front. With regard to tides, the effect in Tacloban was actually neither linear nor additive to the surge, with higher surge coincident to low tides and lower surge coincident to high tides. Lastly, the model run with typhoon having a slower translation speed than Haiyan was found to generate higher surges.

Infiltration and runoff generation processes in fire-affected soils

USGS Publications Warehouse

Moody, John A.; Ebel, Brian A.

2014-01-01

Post-wildfire runoff was investigated by combining field measurements and modelling of infiltration into fire-affected soils to predict time-to-start of runoff and peak runoff rate at the plot scale (1 m2). Time series of soil-water content, rainfall and runoff were measured on a hillslope burned by the 2010 Fourmile Canyon Fire west of Boulder, Colorado during cyclonic and convective rainstorms in the spring and summer of 2011. Some of the field measurements and measured soil physical properties were used to calibrate a one-dimensional post-wildfire numerical model, which was then used as a ‘virtual instrument’ to provide estimates of the saturated hydraulic conductivity and high-resolution (1 mm) estimates of the soil-water profile and water fluxes within the unsaturated zone.Field and model estimates of the wetting-front depth indicated that post-wildfire infiltration was on average confined to shallow depths less than 30 mm. Model estimates of the effective saturated hydraulic conductivity, Ks, near the soil surface ranged from 0.1 to 5.2 mm h−1. Because of the relatively small values of Ks, the time-to-start of runoff (measured from the start of rainfall),  tp, was found to depend only on the initial soil-water saturation deficit (predicted by the model) and a measured characteristic of the rainfall profile (referred to as the average rainfall acceleration, equal to the initial rate of change in rainfall intensity). An analytical model was developed from the combined results and explained 92–97% of the variance of  tp, and the numerical infiltration model explained 74–91% of the variance of the peak runoff rates. These results are from one burned site, but they strongly suggest that  tp in fire-affected soils (which often have low values of Ks) is probably controlled more by the storm profile and the initial soil-water saturation deficit than by soil hydraulic properties.

Development and Design of Cost-Effective, Real-Time Implementable Sediment and Contaminant Release Controls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hampson, Steve

2007-08-01

Alternative design options for integrated storm water and sediment control systems were developed and evaluated for Outfalls 008, 011 and 015 of the Paducah Gaseous Diffusion Plant. The remedial options were required to be cost effective and implementable in a relatively short timeframe. Additionally, construction activities were to minimize earth disturbance, especially with respect to excavation. The current database for storm water and effluent sediment oncentration was assessed for the three outfalls. It was concluded that there was a significant lack of data and recommendations for monitoring equipment were provided to initiate a comprehensive surface water and sediment data acquisitionmore » system. Modeling was completed for current conditions. Peak flow, runoff volume, peak sediment concentration and storm sediment load were modeled for storm events, ranging from 0.5 inches (12.7mm) to 3.0 inches (6.2mm). Predicted peak flows ranged from 2.5 cfs (0.071 m3/s) for Outfall 011 and a 0.5 inches (12.7mm) storm to 210 cfs (5.95 m3/s) for Outfall 008 and a 3.0 inches (76.2mm) storm. Additionally, the 100-yr 24-hr NRCS Type II storm was modeled. Storm sediment loads, for the corresponding outfalls and storm events, ranged from 0.1 to 9.0 tons (8.18 tonnes). Retention ponds were designed and evaluated for each of the three outfalls. The ponds had a dual function; 1) contain the storm runoff volume for smaller storm events and 2) passively treat and discharge runoff that was in excess of the pond’s storage capacity. Stored runoff was transferred to alternative secondary treatment systems. The expected performance of these treatment systems was evaluated. The performance of the outfall ponds was evaluated for storm events ranging from 0.5 inches (12.7mm) to 4.0 inches (101.6mm). Outfall 011 has a watershed of 33.3 acres. Pond 011 (Outfall 011) has the largest storage capacity of the three outfalls, and therefore the highest potential for effective treatment. The predicted sediment trapping efficiency for a 4.0 in (101.6mm) 24-hour storm was 99.7% with an initial empty pond condition. Stored runoff is expected to be transferred to the treatment plant located near Outfall 010. A 4-in storm event accounts for approximately 97% of the average annual precipitation. Pond 015 is relatively small due to the non-excavation restriction. Ninety eight percent and 72.3% sediment trap efficiencies were predicted for a 1.5 in and 3.0 in 24-hour storm; based on the pond being empty at the start of the storm and retained runoff being transferred to one of the secondary treatment systems. A 3-in storm event accounts for approximately 92% of the average annual precipitation. The watershed area of Pond 008 is 113.6 acres and the storage capacity is only 0.92 ac-ft. Sediment trap efficiencies of 96.7%, 77.2% and 67.6% were predicted for storms of 1, 1.5 and 2 inches, respectively. Thus, nearly a 70+% sediment trap efficiency is predicted for storm events of 2 inches or less; accounting for 82% of the average annual precipitation.The approximate quantity of runoff that can be retained and pumped to a secondary treatment system was determined on a storm and annual basis. On an annual basis, Ponds 008, 011 and 015 are expected to retain 20.2%, 83.1% and 34.7% of the generated runoff, respectively. Retained runoff will be pumped to alternative treatment systems. The alternative treatment systems designed and evaluated are: 1) evapotranspiration-only, 2) evapotranspiration - infiltration and 3) a combination weep berm – grass filter control system. The evapotranspiration-only method would result in complete treatment of the runoff transferred from the retention pond. The evapotranspiration - infiltration technique is expected to result in treatment through filtration and natural attenuation of soil and associated constituents. Both drip and micro-sprinklers were evaluated for the first two listed treatment systems. Outfall 015 was used to illustrate the evaporation –only and evapotranspiration – infiltration secondary treatment methods. Based on a 5 acre site and a very conservative evapotranspiration rate, i.e. a low value of 0.10 in/day, a completely full Pond 015 would take approximately 10 days to empty by the drip irrigation system design. For a 25 acre site, the dewatering time would, of course, be 2 days. For the micro-sprinkler irrigation system 8 and 1 ¾ days would be required for the 5 acre and 25 acre sites, respectively. When the evapotranspiration – infiltration treatment system was employed the drip irrigation system, based on a 5 acre site, would take 2 days to dewatering Pond 015; 1/10 of the evapotranspiration-only method. For the micro-sprinklers, with a 5 acre site the dewatering time would be 1 ¾ days. A comprehensive irrigation design was completed for each alternative scenario and a listing of all major system components was provided. Outfall 008 was used to illustrate the combination weep berm – grass filter treatment system. Such a system has proven to be very effective at other applied research and at international hard rock mines. Design considerations were provided encompassing dewatering pumping rate, sediment load and concentration, soil type, weep berm characteristics and grass filter length and infiltration rates. The expected performance of a combination weep berm – grass filter system design was illustrated through a detailed example and SEDCAD modeling. The retention pond – weep berm – grass filter, for the illustrated example, resulted in a peak effluent sediment concentration at the end of the grass filter of 2 mg« less

Bioretention storm water control measures decrease the toxicity of copper roof runoff.

PubMed

LaBarre, William J; Ownby, David R; Rader, Kevin J; Lev, Steven M; Casey, Ryan E

2017-06-01

The present study evaluated the ability of 2 different bioretention storm water control measures (SCMs), planter boxes and swales, to decrease the toxicity of sheet copper (Cu) roofing runoff to Daphnia magna. The present study quantified changes in storm water chemistry as it passed through the bioretention systems and utilized the biotic ligand model (BLM) to assess whether the observed D. magna toxicity could be predicted by variations found in water chemistry. Laboratory toxicity tests were performed using select storm samples with D. magna cultured under low ionic strength conditions that were appropriate for the low ionic strength of the storm water samples being tested. The SCMs decreased toxicity of Cu roof runoff in both the BLM results and the storm water bioassays. Water exiting the SCMs was substantially higher than influent runoff in pH, ions, alkalinity, and dissolved organic carbon and substantially lower in total and dissolved Cu. Daphnids experienced complete mortality in untreated runoff from the Cu roof (the SCM influent); however, for planter and swale effluents, survival averaged 86% and 95%, respectively. The present study demonstrated that conventional bioretention practices, including planter boxes and swales, are capable of decreasing the risk of adverse effects from sheet Cu roof runoff to receiving systems, even before considering dilution of effluents in those receiving systems and associated further reductions in copper bioavailability. Environ Toxicol Chem 2017;36:1680-1688. © 2016 SETAC. © 2016 SETAC.

Exploring Lightning Jump Characteristics

NASA Technical Reports Server (NTRS)

Chronis, Themis; Carey, Larry D.; Schultz, Christopher J.; Schultz, Elise; Calhoun, Kristin; Goodman, Steven J.

2014-01-01

This study is concerned with the characteristics of storms exhibiting an abrupt temporal increase in the total lightning flash rate (i.e., lightning jump, LJ). An automated storm tracking method is used to identify storm "clusters" and total lightning activity from three different lightning detection systems over Oklahoma, northern Alabama and Washington, D.C. On average and for different employed thresholds, the clusters that encompass at least one LJ (LJ1) last longer, relate to higher Maximum Expected Size of Hail, Vertical Integrated Liquid and lightning flash rates (area-normalized) than the clusters that did not exhibit any LJ (LJ0). The respective mean values for LJ1 (LJ0) clusters are 80 min (35 min), 14 mm (8 mm), 25 kg per square meter (18 kg per square meter) and 0.05 flash per min per square kilometer (0.01 flash per min per square kilometer). Furthermore, the LJ1 clusters are also characterized by slower decaying autocorrelation functions, a result that implies a less "random" behavior in the temporal flash rate evolution. In addition, the temporal occurrence of the last LJ provides an estimate of the time remaining to the storm's dissipation. Depending of the LJ strength (i.e., varying thresholds), these values typically range between 20-60 min, with stronger jumps indicating more time until storm decay. This study's results support the hypothesis that the LJ is a proxy for the storm's kinematic and microphysical state rather than a coincidental value.

Superposed Epoch Analysis of Ring Current Geoeffectiveness Related to Solar Wind and Plasma Sheet Drivers

NASA Technical Reports Server (NTRS)

Liemohm, M. W.; Kozyra, J. U.; Thomsen, M. F.; Borovsky, J. E.; Gahurthakurta, Madulika (Technical Monitor)

2004-01-01

The goal of that proposal was to examine the relationship between solar wind drivers and ring current dynamics through data analysis and numerical simulations. The data analysis study was a statistical examination (via superposed epoch analyses) of a solar cycle's worth of storm data. Solar wind data, geophysical indices, and geosynchronous plasma data were collected for every time period with Dst< -50 nT from 1989 through 2002, and the storm list now exceeds 400 entries. This work was first conducted by a summer undergraduate student, Mr. John Vann (University of Kansas), with funding from the NSF Research Experience for Undergraduates program. It was then continued by a University of Michigan graduate student, Mr. Jichun Zhang. Mr. Zhang is now in his fourth year at U-M and is progressing very well toward a PhD in space science. His dissertation will be based on his data analysis and modeling efforts using this geomagnetic storm database. The results of the data analysis study have been the focus of several conference presentations, and the first manuscript has just been published. Two additional papers are presently being prepared, one on average (superposed) solar wind features for various storm subsets (e.g., intense storms at solar maximum), and another on geosynchronous plasma features for these same storm subsets. The latter result was highlighted by the TR&T program director in his presentation at the COSPAR meeting this summer.

On using scatterometer and altimeter data to improve storm surge forecasting in the Adriatic Sea

NASA Astrophysics Data System (ADS)

Bajo, Marco; Umgiesser, Georg; De Biasio, Francesco; Vignudelli, Stefano; Zecchetto, Stefano

2017-04-01

Satellite data are seldom used in storm surge forecasting. Among the most important issues related to the storm surge forecasting are the quality of the model wind forcing and the initial condition of the sea surface elevation. In this work, focused on storm surge forecasting in the Adriatic Sea, satellite scatterometer wind data are used to correct the wind speed and direction biases of the ECMWF global atmospheric model by tuning the spatial fields, as an alternative to data assimilation. The capability of such an unbiased wind is tested against that of a high resolution wind, produced by a regional non-hydrostatic model. On the other hand, altimeter Total Water Level Envelope (TWLE) data, which provide the sea level elevation, are used to improve the accuracy of the initial state of the model simulations. This is done by assimilating into a storm surge model the TWLE obtained by the altimeter observations along ground tracks, after subtraction of the tidal components. In order to test the methodology, eleven storm surge events recorded in Venice, from 2008 to 2012, have been simulated using different configurations of forcing wind and altimeter data assimilation. Results show that the relative error on the estimation of the maximum surge peak, averaged over the cases considered, decreases from 13% to 7% using both the unbiased wind and the altimeter data assimilation, while forcing the hydrodynamic model with the high resolution wind (no tuning), the altimeter data assimilation reduces the error from 9% to 6%.

Sensitivity analysis of the DRAINWAT model applied to an agricultural watershed in the lower coastal plain, North Carolina, USA

Treesearch

Hyunwoo Kim; Devendra M. Amatya; Stephen W. Broome; Dean L. Hesterberg; Minha Choi

2011-01-01

The DRAINWAT, DRAINmod for WATershed model, was selected for hydrological modelling to obtain water table depths and drainage outflows at Open Grounds Farm in Carteret County, North Carolina, USA. Six simulated storm events from the study period were compared with the measured data and analysed. Simulation results from the whole study period and selected rainfall...

Coastal change from Hurricane Sandy and the 2012-13 winter storm season: Fire Island, New York

USGS Publications Warehouse

Hapke, Cheryl J.; Brenner, Owen; Henderson, Rachel E.; Reynolds, B.J.

2013-01-01

The U.S. Geological Survey (USGS) mounted a substantial effort in response to Hurricane Sandy including an assessment of the morphological impacts to the beach and dune system at Fire Island, New York. Field surveys of the beach and dunes collected just prior to and after landfall were used to quantify change in several focus areas. In order to quantify morphologic change along the length of the island, pre-storm (May 2012) and post-storm (November 2012) lidar and aerial photography were used to assess changes to the shoreline and beach, and to measure volumetric changes. The extent and thicknesses of overwash deposits were mapped in the field, and measurements were used to determine volume, distribution, and characteristics of the deposits. The beaches and dunes on Fire Island were severely eroded during Hurricane Sandy, and the island breached in three locations on the eastern segment of the island. Landward shift of the upper portion of the beach averaged 19.7 meters (m) but varied substantially along the coast. Shoreline change was also highly variable, but the shoreline prograded during the storm by an average of 11.4 m, due to the deposition of material eroded from the upper beach and dunes onto the lower portion of the beach. The beaches and dunes lost 54.4 percent of their pre-storm volume, and the dunes experienced overwash along 46.6 percent of the island. The inland overwash deposits account for 14 percent of the volume lost from the beaches and dunes, indicating that the majority of material was moved offshore. In the winter months following Hurricane Sandy, seven storm events with significant wave heights greater than four m were recorded at a wave buoy 30 nautical miles south of Fire Island. Monthly shoreline and profile surveys indicate that the beach continued to erode dramatically. The shoreline, which exhibited a progradational trend immediately after Sandy, eroded an average of 21.4 m between November 2012 and mid-March 2013, with a maximum landward shift of nearly 60 m. By March 2013 the elevation of the beach in the majority of the surveyed profiles was lowered below the mean high water level (0.46 m), and the beach lost an additional 18.9 percent of its remaining volume. In the final time period of the field surveys (March to April 2013), the beach began to show signs of rapid recovery, and in 90 percent of the profiles, the volume of the beach in April 2013 was similar to the volume measured immediately after Hurricane Sandy. Overall, Hurricane Sandy profoundly impacted the morphology of Fire Island and resulted in an extremely low elevation, low relief configuration that has left the barrier island vulnerable to future storms. The coastal system subsequently began to show signs of recovery, and although the beach is likely to experience continued recovery in the form of volume gains, the dunes will take years to rebuild. Events such as Sandy result in a coastal environment that is a more vulnerable to future storm impacts, but they are an important natural process of barrier islands that allow these systems to evolve in response to sea-level rise.

Segmentation and Contrasting Magma Supply Along the South-East Indian Ridge, 130°E to 140°E: Results of the STORM Cruise

NASA Astrophysics Data System (ADS)

Briais, A.; Ruellan, E.; Maia, M.; Hemond, C.; Hanan, B. B.; Ceuleneer, G.; Graham, D. W.; Park, S. H.

2017-12-01

We present observations of the South-East Indian Ridge (SEIR) between 130°E to 140°E, mostly collected during the STORM cruise (South Tasmania Ocean Ridge and Mantle) on the N/O L'Atalante. The SEIR displays large variations of axial depth despite an almost constant intermediate full spreading rate of 75 km/m.y. In the study area the analysis of multibeam bathymetry maps shows that the axis displays a rise morphology to the east away from the discontinuities, and a rifted high morphology in the west and near the OSCs, as often observed along intermediate-spreading mid-ocean ridges. The ridge axis is offset by 27 km at 131°E and 20 km at 135°E by two large-offset overlapping spreading centers (OSCs) propagating westward, and by a smaller OSC at 137°17'E. These OSCs define four second-order ridge segments (A2 to A5 from west to east). We observe a general shallowing of the ridge axis from 3100 m depth in the west to 2400 m depth in the east, and a prominent deepening of the axis near the large OSCs. The easternmost segment A5 shows a very shallow axial ridge suggesting a robust magma supply despite its proximity to the George V transform fault (140°E). Major element variations in basalt glasses are systematically related to morphotectonic segmentation of the ridge axis, showing contrasts in crystal fractionation from one segment to another that may relate to differences in replenishment of axial melt lenses by primitive melts. Along segment A5, crystallization increases with proximity to the George V transform fault, consistent with an expected cold edge effect. In contrast, along segment A3 the extent of crystallization increases progressively from east to west in the direction of ridge propagation. *STORM Cruise Scientific Party: F. Barrere, C. Boulart, A. Briais, D. Brunelli, G. Ceuleneer, N. Ferreira, D. Graham, B. Hanan, C. Hémond, S. Macleod, M. Maia, A. Maillard, S. Merkuryev, S.H. Park, S. Révillon, E. Ruellan, A. Schohn, S. Watson, and Y.S. Yang.

Sedimentology of gravelly Lake Lahontan highstand shoreline deposits, Churchill Butte, Nevada, USA

NASA Astrophysics Data System (ADS)

Blair, Terence C.

1999-02-01

Gravelly shoreline deposits of the latest Pleistocene highstand of Lake Lahontan occur in pristine depositional morphology, and are exposed in gravel pits along Churchill Butte in west-central Nevada. Four environments differentiated at this site are alluvial fan/colluvium, lakeshore barrier spit, lake lower-shoreface spit platform, and lake bottom. Lakeshore deposits abut, along erosional wave headcuts, either unsorted muddy to bouldery colluvium fringing Churchill Butte bedrock, or matrix-supported, cobbly and pebbly debris-flow deposits of the Silver Springs fan. The lakeshore barrier spit is dominated by granule pebble gravel concentrated by wave erosion of the colluvial and alluvial-fan facies. The lakeward side of the barrier consists of beachface deposits of well-sorted granules or pebbles in broad, planar beds 1-10 cm thick and sloping 10-15°. They interfinger downslope with thicker (10-25 cm) and less steep (5-10°) lakeward-dipping beds of fine to medium pebble gravel of the lake upper shoreface. Interstratified with the latter are 10-40-cm-thick sets of high-angle cross-beds that dip southward, alongshore. Higher-angle (15-20°), landward-dipping foresets of similar texture but poorer sorting comprise the proximal backshore on the landward side of the barrier. They were deposited during storm surges that overtopped the barrier berm. Gastropod-rich sand and mud, also deposited by storm-induced washover, are found landward of the gravel foresets in a 15-m-wide backshore pond. Algal stromatolites, ostracodes, and diatoms accumulated in this pond between storm events. The lake lower shoreface, extending from water depths of 2 to 8 m, consists of a southward-prograding spit platform built by longshore drift. The key component of this platform is large-scale sandy pebble gravel in 16° southward-dipping `Gilbert' foresets that grade at a water depth of about 6-7 m to 4°-dipping sandy toesets. A shift from bioturbated lower-shoreface sand and silt, to flat and laminated lake-bottom silt and mud, occurs between water depths of 10-40 m and over a shore-normal distance of ≥250 m. This lake-bottom mud facies, unlike the others, is areally expansive.

Atmospheric particles retrieval using satellite remote sensing: Applications for sandstorms and volcanic clouds

NASA Astrophysics Data System (ADS)

Gu, Yingxin

This thesis is concerned with atmospheric particles produced by sandstorms and volcanic eruptions. Three studies were conducted in order to examine particle retrieval methodology, and apply these towards an improved understanding of large-scale sandstorms. A thermal infrared remote sensing retrieval method developed by Wen and Rose [1994], which retrieves particle sizes, optical depth, and total masses of silicate particles in the volcanic cloud, was applied to an April 07, 2001 sandstorm over northern China, using MODIS. Results indicate that the area of the dust cloud observed was 1.34 million km2, the mean particle radius of the dust was 1.44 mum, and the mean optical depth at 11 mum was 0.79. The mean burden of dust was approximately 4.8 tons/km2 and the main portion of the dust storm on April 07, 2001 contained 6.5 million tons of dust. The results are supported by both independent remote sensing data (TOMS) and in-situ data for a similar event in 1998, therefore suggesting that the technique is appropriate for quantitative analysis of silicate dust clouds. This is the first quantitative evaluation of annual and seasonal dust loading in 2003 produced by Saharan dust storms by satellite remote sensing analysis. The retrieved mean particle effective radii of 2003 dust events are between 1.7--2.6 mum which is small enough to be inhaled and is hazardous to human health. The retrieved yearly dust mass load is 658--690 Tg, which is ˜45% of the annual global mineral dust production. Winter is the heaviest dust loading season in the year 2003, which is more than 5 times larger than that in the summer season in 2003.The mean optical depths at 11 mum in the winter season (around 0.7) are higher than those in the summer season (around 0.5). The results could help both meteorologists and environmental scientists to evaluate and predict the hazard degree caused by Saharan dust storms. (Abstract shortened by UMI.)

Maximizing effectiveness of adaptation action in Pacific Island communities using coastal wave attenuation models

NASA Astrophysics Data System (ADS)

Jung, H.; Carruthers, T.; Allison, M. A.; Weathers, D.; Moss, L.; Timmermans, H.

2017-12-01

Pacific Island communities are highly vulnerable to the effects of climate change, specifically accelerating rates of sea level rise, changes to storm intensity and associated rainfall patterns resulting in flooding and shoreline erosion. Nature-based adaptation is being planned not only to reduce the risk from shoreline erosion, but also to support benefits of a healthy ecosystem (e.g., supporting fisheries or coral reefs). In order to assess potential effectiveness of the nature-based actions to dissipate wave energy, two-dimensional X-Beach models were developed to predict the wave attenuation effect of coastal adaptation actions at the pilot sites—the villages of Naselesele and Somosomo on Taveuni island, Fiji. Both sites are experiencing serious shoreline erosion due to sea level rise and storm wave. The water depth (single-beam bathymetry), land elevation (truck-based LiDAR), and vegetation data including stem density and height were collected in both locations in a June 2017 field experiment. Wave height and water velocity were also measured for the model setup and calibration using a series of bottom-mounted instruments deployed in the 0-15 m water depth portions of the study grid. The calibrated model will be used to evaluate a range of possible adaptation actions identified by the community members of Naselesele and Somosomo. Particularly, multiple storm scenario runs with management-relevant shoreline restoration/adaptation options will be implemented to evaluate efficiencies of each adaptation action (e.g., no action, with additional planted trees, with sand mining, with seawalls constructed with natural materials, etc.). These model results will help to better understand how proposed adaption actions may influence future shoreline change and maximize benefits to communities in island nations across the SW Pacific.

Evaporation of impact water droplets in interception processes: Historical precedence of the hypothesis and a brief literature overview

NASA Astrophysics Data System (ADS)

Dunkerley, David L.

2009-10-01

SummaryIntra-storm evaporation depths exceed post-storm evaporation depths in the interception of rainfall on plant canopies. An important fraction of the intra-storm evaporation may involve the small impact (or splash) droplets produced when raindrops, and perhaps gravity drops (drips released from plant parts), collide with wet plant surfaces. This idea has been presented as a new conception by Murakami [Murakami, S., 2006. A proposal for a new forest canopy interception mechanism: splash droplet evaporation. Journal of Hydrology 319, 72-82; Murakami, S., 2007a. Application of three canopy interception models to a young stand of Japanese cypress and interpretation in terms of interception mechanism. Journal of Hydrology 342, 305-319; Murakami, S., 2007b. A follow-up for the splash droplet evaporation hypothesis of canopy interception and remaining problems: why is humidity unsaturated during rainfall? In: Proceedings of the 20th Annual Conference. Japan Society of Hydrology and Water Resources (in Japanese). < http://www.jstage.jst.go.jp/article/jshwr/20/0/20_62/_article>] but was in fact advanced by Dunin [Dunin, F.X., O'Loughlin, E.M., Reyenga, W., 1988. Interception loss from eucalypt forest: lysimeter determination of hourly rates for long term evaluation. Hydrological Processes 2, 315-329] more than 20 years ago. In addition, Dunin et al. considered that canopy ventilation might be enhanced in intense rain. This note draws attention to the historical precedence of the work of Dunin et al. and also presents a short review of literature on impact droplet production, highlighting areas where data are still required for the full exploration of the role of droplet evaporation in canopy interception. Droplet production needs to be properly parameterised and included in models of interception processes and landsurface-atmosphere interactions.

Derivation of flood frequency curves in poorly gauged Mediterranean catchments using a simple stochastic hydrological rainfall-runoff model

NASA Astrophysics Data System (ADS)

Aronica, G. T.; Candela, A.

2007-12-01

SummaryIn this paper a Monte Carlo procedure for deriving frequency distributions of peak flows using a semi-distributed stochastic rainfall-runoff model is presented. The rainfall-runoff model here used is very simple one, with a limited number of parameters and practically does not require any calibration, resulting in a robust tool for those catchments which are partially or poorly gauged. The procedure is based on three modules: a stochastic rainfall generator module, a hydrologic loss module and a flood routing module. In the rainfall generator module the rainfall storm, i.e. the maximum rainfall depth for a fixed duration, is assumed to follow the two components extreme value (TCEV) distribution whose parameters have been estimated at regional scale for Sicily. The catchment response has been modelled by using the Soil Conservation Service-Curve Number (SCS-CN) method, in a semi-distributed form, for the transformation of total rainfall to effective rainfall and simple form of IUH for the flood routing. Here, SCS-CN method is implemented in probabilistic form with respect to prior-to-storm conditions, allowing to relax the classical iso-frequency assumption between rainfall and peak flow. The procedure is tested on six practical case studies where synthetic FFC (flood frequency curve) were obtained starting from model variables distributions by simulating 5000 flood events combining 5000 values of total rainfall depth for the storm duration and AMC (antecedent moisture conditions) conditions. The application of this procedure showed how Monte Carlo simulation technique can reproduce the observed flood frequency curves with reasonable accuracy over a wide range of return periods using a simple and parsimonious approach, limited data input and without any calibration of the rainfall-runoff model.

Establishing storm thresholds for the Spanish Gulf of Cádiz coast

NASA Astrophysics Data System (ADS)

Del Río, Laura; Plomaritis, Theocharis A.; Benavente, Javier; Valladares, María; Ribera, Pedro

2012-03-01

In this study critical thresholds are defined for storm impacts along the Spanish coast of the Gulf of Cádiz. The thresholds correspond to the minimum wave and tide conditions necessary to produce significant morphological changes on beaches and dunes and/or damage on coastal infrastructure or human occupation. Threshold definition was performed by computing theoretical sea-level variations during storms and comparing them with the topography of the study area and the location of infrastructure at a local level. Specifically, the elevations of the berm, the dune foot and the entrance of existing washovers were selected as threshold parameters. The total sea-level variation generated by a storm event was estimated as the sum of the tidal level, the wind-induced setup, the barometric setup and the wave-associated sea-level variation (wave setup and runup), assuming a minimum interaction between the different processes. These components were calculated on the basis of parameterisations for significant wave height (Hs) obtained for the oceanographic and environmental conditions of the Gulf of Cadiz. For this purpose real data and reanalysis time-series (HIPOCAS project) were used. Validation of the obtained results was performed for a range of coastal settings over the study area. The obtained thresholds for beach morphological changes in spring tide conditions range between a significant wave height of 1.5 m and 3.7 m depending on beach characteristics, while for dune foot erosion are around 3.3 to 3.7 m and for damage to infrastructure around 7.2 m. In case of neap tide conditions these values are increased on average by 50% over the areas with large tidal range. Furthermore, records of real damage in coastal infrastructure caused by storms were collected at a regional level from newspapers and other bibliographic sources and compared with the hydrodynamic conditions that caused the damage. These were extracted from the hindcast database of the HIPOCAS project, including parameters such as storm duration, mean and maximum wave height and wave direction. Results show that the duration of the storm is not critical in determining the occurrence of coastal damage in the regional study area. This way, the threshold would be defined as a duration ≥30 h, with moderate average wave height (≥3.3 m) and high maximum wave height (≥4.1 m) approaching from the 3rd and 4th quadrants, during mean or spring tide situation. The calculated thresholds constitute snapshots of risk conditions within a certain time framework. Beach and nearshore zones are extremely dynamic, and also the characteristics of occupation on the coast change over time, so critical storm thresholds will change accordingly and therefore will need to be updated.

Cyclone Nargis survey in Myanmar's Ayeyarwady River delta

NASA Astrophysics Data System (ADS)

Fritz, H. M.; Blount, C.; Thwin, S.; Thu, M. K.; Chan, N.

2008-12-01

Tropical cyclone Nargis (Cat. 4) made landfall on May 2, 2008, causing the worst natural disaster in Myanmar's recorded history. Official death toll estimates exceed 130,000 fatalities making it the 7th deadliest cyclone ever recorded worldwide. Nargis took a rare nearly eastern track over the Bay of Bengal while developing sustained winds over 210 km/h with gusts up to 260 km/h hours prior to landfall in Myanmar at untypically low latitude near 16°N. It then proceeded northeast and approximately 12 hours later weakened to a Category 1 storm with sustained wind speeds of 130 km/h as it passed over Yangon. The first independent storm surge reconnaissance team was deployed to Myanmar from 9 to 23 August 2008. Cyclone Nargis struck low-lying coastal plains particularly vulnerable to storm surge flooding due to the lack of effective barriers. The team surveyed coastal and inland villages from Pyapon to Purian Point, encompassing the Bogale and Ayeyarwady River mouths. The survey by boat spanned more than 150 km parallel to the cyclone track between Pyapon and Pyinkhayan encompassing 20 hardest hit settlements such as Pyinsalu. More than 1m vertical erosion and 150 m land loss were measured at various coastal locations such as Aya. Massive deforestation of mangroves and land use were documented. Maximum storm surge elevations and overland flow depths were measured based on water marks on buildings, scars on trees, and rafted debris. The storm surge peaked in the landfall area south of Pyinkhayan and eastwards in Pyinsalu exceeding 5m. Storm waves more than 2m high were superimposed on the storm surge level in most areas according to eyewitnesses. Inundation distances reached beyond 50 km inland. Catastrophic peak fatality rates exceeded 80% in hardest hit villages with the majority being children and women. The high water marks and fatality rates significantly exceeded corresponding 2004 Indian Ocean tsunami values at every location. Eyewitnesses were interviewed to document the time history of the event, survival strategies, cyclone awareness and evacuation. At the end of the 3 month relief operations survivors were left drinking from rice paddies with contaminated wells and no source of safe drinking water besides rain water. Storm surge simulations can be benchmarked against the measured cyclone Nargis storm surge and inundation to perform vulnerability analysis. Unfortunately, the widely deforested, low lying and densely populated Ayeyarwady delta remains extremely vulnerable to future storm surge flooding or potential sea level rise.

Statistical Aspects of Tropical Cyclone Activity in the North Atlantic Basin, 1945-2010

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2012-01-01

Examined are statistical aspects of the 715 tropical cyclones that formed in the North Atlantic basin during the interval 1945-2010. These 715 tropical cyclones include 306 storms that attained only tropical storm strength, 409 hurricanes, 179 major or intense hurricanes, and 108 storms that struck the US coastline as hurricanes. Comparisons made using 10-year moving average (10-yma) values between tropical cyclone parametric values and surface air and ENSO-related parametric values indicate strong correlations to exist, in particular, against the Armagh Observatory (Northern Ireland) surface air temperature, the Atlantic Multi-decadal Oscillation (AMO) index, the Atlantic Meridional Mode (AMM) index, and the North Atlantic Oscillation (NAO) index, in addition to the Oceanic Ni o index (ONI) and Quasi-Biennial Oscillation (QBO) indices. Also examined are the decadal variations of the tropical cyclone parametric values and a look ahead towards the 2012 hurricane season and beyond.

Seasonality, phytoplankton succession and the biogeochemical impacts of an autumn storm in the northeast Atlantic Ocean

NASA Astrophysics Data System (ADS)

Painter, Stuart C.; Finlay, Madelaine; Hemsley, Victoria S.; Martin, Adrian P.

2016-03-01

Phytoplankton chemotaxonomic distributions are examined in conjunction with taxon specific particulate biomass concentrations and phytoplankton abundances to investigate the biogeochemical consequences of the passage of an autumn storm in the northeast Atlantic Ocean. Chemotaxonomy indicated that the phytoplankton community was dominated by nanoplankton (2-20 μm), which on average represented 75 ± 8% of the community. Microplankton (20-200 μm) and picoplankton (<2 μm) represented 21 ± 7% and 4 ± 3% respectively with the microplankton group composed of almost equal proportions of diatoms (53 ± 17%) and dinoflagellates (47 ± 17%). Total chlorophyll-a (TCHLa = CHLa + Divinyl CHLa) concentrations ranged from 22 to 677 ng L-1, with DvCHLa making minor contributions of between <1% and 13% to TCHLa. Higher DvCHLa contributions were seen during the storm, which deepened the surface mixed layer, increased mixed layer nutrient concentrations and vertically mixed the phytoplankton community leading to a post-storm increase in surface chlorophyll concentrations. Picoplankton were rapid initial respondents to the changing conditions with pigment markers showing an abrupt 4-fold increase in proportion but this increase was not sustained post-storm. 19‧-HEX, a chemotaxonomic marker for prymnesiophytes, was the dominant accessory pigment pre- and post-storm with concentrations of 48-435 ng L-1, and represented 44% of total carotenoid concentrations. Accompanying scanning electron microscopy results support the pigment-based analysis but also provide detailed insight into the nano- and microplankton communities, which proved to be highly variable between pre-storm and post-storm sampling periods. Nanoplankton remained the dominant size class pre- and post-storm but the microplankton proportion peaked during the period of maximum nutrient and chlorophyll concentrations. Classic descriptions of autumn blooms resulting from storm driven eutrophication events promoting phytoplankton growth in surface waters should be tempered with greater understanding of the role of storm driven vertical reorganization of the water column and of resident phytoplankton communities. Crucially, in this case we observed no change in integrated chlorophyll, particulate organic carbon or biogenic silica concentrations despite also observing a ∼50% increase in surface chlorophyll concentrations which indicated that the surface enhancement in chlorophyll concentrations was most likely fed from below rather than resulting from in situ growth. Though not measured directly there was no evidence of enhanced export fluxes associated with this storm. These observations have implications for the growing practice of using chlorophyll fluorescence from remote platforms to determine ocean productivity late in the annual productivity period and in response to storm mixing.

Hydrography and bottom boundary layer dynamics: Influence on inner shelf sediment mobility, Long Bay, North Carolina

USGS Publications Warehouse

Davis, L.A.; Leonard, L.A.; Snedden, G.A.

2008-01-01

This study examined the hydrography and bottom boundary-layer dynamics of two typical storm events affecting coastal North Carolina (NC); a hurricane and the passages of two small consecutive extratropical storms during November 2005. Two upward-looking 1200-kHz Acoustic Doppler Current Profilers (ADCP) were deployed on the inner shelf in northern Long Bay, NC at water depths of less than 15 m. Both instruments profiled the overlying water column in 0.35 in bins beginning at a height of 1.35 in above the bottom (mab). Simultaneous measurements of wind speed and direction, wave and current parameters, and acoustic backscatter were coupled with output from a bottom boundary layer (bbl) model to describe the hydrography and boundary layer conditions during each event. The bbl model also was used to quantify sediment transport in the boundary layer during each storm. Both study sites exhibited similar temporal variations in wave and current magnitude, however, wave heights during the November event were higher than waves associated with the hurricane. Near-bottom mean and subtidal currents, however, were of greater magnitude during the hurricane. Peak depth-integrated suspended sediment transport during the November event exceeded transport associated with the hurricane by 25-70%. Substantial spatial variations in sediment transport existed throughout both events. During both events, along-shelf sediment transport exceeded across-shelf transport and was related to the magnitude and direction of subtidal currents. Given the variations in sediment type across the bay, complex shoreline configuration, and local bathymetry, the sediment transport rates reported here are very site specific. However, the general hydrography associated with the two storms is representative of conditions across northern Long Bay. Since the beaches in the study area undergo frequent renourishment to counter the effects of beach erosion, the results of this study also are relevant to coastal management decision-making. Specifically, these issues include 1) identification of municipalities that should share the cost for renourishment given the likelihood for significant along-shelf sand movement and 2) appropriate timing of sand placement with respect to local climatology and sea-turtle nesting restrictions.

Curve Number Application in Continuous Runoff Models: An Exercise in Futility?

NASA Astrophysics Data System (ADS)

Lamont, S. J.; Eli, R. N.

2006-12-01

The suitability of applying the NRCS (Natural Resource Conservation Service) Curve Number (CN) to continuous runoff prediction is examined by studying the dependence of CN on several hydrologic variables in the context of a complex nonlinear hydrologic model. The continuous watershed model Hydrologic Simulation Program-FORTRAN (HSPF) was employed using a simple theoretical watershed in two numerical procedures designed to investigate the influence of soil type, soil depth, storm depth, storm distribution, and initial abstraction ratio value on the calculated CN value. This study stems from a concurrent project involving the design of a hydrologic modeling system to support the Cumulative Hydrologic Impact Assessments (CHIA) of over 230 coal-mined watersheds throughout West Virginia. Because of the large number of watersheds and limited availability of data necessary for HSPF calibration, it was initially proposed that predetermined CN values be used as a surrogate for those HSPF parameters controlling direct runoff. A soil physics model was developed to relate CN values to those HSPF parameters governing soil moisture content and infiltration behavior, with the remaining HSPF parameters being adopted from previous calibrations on real watersheds. A numerical procedure was then adopted to back-calculate CN values from the theoretical watershed using antecedent moisture conditions equivalent to the NRCS Antecedent Runoff Condition (ARC) II. This procedure used the direct runoff produced from a cyclic synthetic storm event time series input to HSPF. A second numerical method of CN determination, using real time series rainfall data, was used to provide a comparison to those CN values determined using the synthetic storm event time series. It was determined that the calculated CN values resulting from both numerical methods demonstrated a nonlinear dependence on all of the computational variables listed above. It was concluded that the use of the Curve Number as a surrogate for the selected subset of HPSF parameters could not be justified. These results suggest that use of the Curve Number in other complex continuous time series hydrologic models may not be appropriate, given the limitations inherent in the definition of the NRCS CN method.

Spatial and temporal variation of acoustic backscatter in the STRESS experiment

NASA Astrophysics Data System (ADS)

Dworski, J. George; Jackson, Darrell R.

1994-08-01

Acoustic backscatter measurements were made of the seabed with a bottom mounted, circularly scanning sonar. The placement was at 91 m depth, mid-shelf of Northern California (38° 34'N), site C3 of the experiment STRESS I (1988-1989). Our expectation was that sonar images (70 m radius, 12,000 m 2) would provide a means of observing, over a large field of view, changes in the bottom due to storm-induced sediment transport and due to bioturbation. This expectation was supported in part by towed sonar measurements at 35 kHz over a sandy area in the North Sea, where dramatic spatial variation in the level of the backseattered signal was observed during an Autumn storm on scales of a few km with no concomitant change in sediment grain size [ JACKSONet al. (1986) The Journal of the Acoustical Society of America, 80, 1188-1199]. It appeared possible that storm-driven sediment transport might have been responsible for this patchiness, by altering bottom roughness and by redeposition of suspended material. At the California site, a conventional sonar processing of our data from the STRESS experiment reveals no such dramatic change in backscattered signal level due to storms. The sonar images contain random structures whose time evolution is subtle and difficult to interpret. A much clearer picture of temporal and spatial variations emerges from a processing scheme involving cross-correlation of time-separated acoustic views of the bottom. In effect, the sequence of correlation data images produces a movie in which patches of activity are seen to develop as functions of time. It appears that most of this activity is biological rather than hydrodynamic. A tentative explanation is two-fold. The bottom shear stress might have been considerably greater at the North Sea site (with depth only one-half of the California site). The seafloor at the California site was silty-clayey, and backscatter from such floor is less sensitive to the water-floor interface shape and roughness than it would be to the same parameters of a sandy bottom.

Investigations of Desert Dust and Smoke in the North Atlantic in Support of the TOMS Instrument

NASA Technical Reports Server (NTRS)

Toon, Owen B.

2005-01-01

During the initial period of the work we concentrated on Saharan dust storms and published a sequence of papers (Colarco et a1 2002,2003a,b, Toon, 2004). The U.S. Air Force liked the dust model so well that they appropriated it for operational dust storm forecasting (Barnum et al., 2004). The Air Force has used it for about 5 yrs in the Middle East where dust storms cause significant operational problems. The student working on this project, Peter Colarco, has graduated and is now a civil servant at Goddard where he continues to interact with the TOMS team. This work helped constrain the optical properties of dust at TOMS wavelengths, which is useful for climate simulations and for TOMS retrievals of dust properties such as optical depth. We also used TOMS data to constrain the sources of dust in Africa and the Middle East, to determine the actual paths taken by Saharan dust storms, to learn more about the mechanics of variations in the optical depths, and to learn more about the mechanisms controlling the altitudes of the dust. During the last two years we have been working on smoke from fires. Black carbon aerosols are one of the leading factors in radiative forcing. The US Climate Change Science Program calls this area out for specific study. It has been suggested by Jim Hansen, and Mark Jacobsen among others, that by controlling emissions of black carbon we might reduce greenhouse radiative forcing in a relatively painless manner. However, we need a greatly improved understanding of the amount of black carbon in the atmosphere, where it is located, where it comes from, how it is mixed with other particles, what its actual optical properties are, and how it evolves. In order to learn about these issues we are using a numerical model of smoke. We have applied this model to the SAFARI field program data, and used the TOMS satellite observations in that period (Sept. 2000). Our goal is to constrain source function estimates for black carbon, and smoke optical properties.

Domain-averaged snow depth over complex terrain from flat field measurements

NASA Astrophysics Data System (ADS)

Helbig, Nora; van Herwijnen, Alec

2017-04-01

Snow depth is an important parameter for a variety of coarse-scale models and applications, such as hydrological forecasting. Since high-resolution snow cover models are computational expensive, simplified snow models are often used. Ground measured snow depth at single stations provide a chance for snow depth data assimilation to improve coarse-scale model forecasts. Snow depth is however commonly recorded at so-called flat fields, often in large measurement networks. While these ground measurement networks provide a wealth of information, various studies questioned the representativity of such flat field snow depth measurements for the surrounding topography. We developed two parameterizations to compute domain-averaged snow depth for coarse model grid cells over complex topography using easy to derive topographic parameters. To derive the two parameterizations we performed a scale dependent analysis for domain sizes ranging from 50m to 3km using highly-resolved snow depth maps at the peak of winter from two distinct climatic regions in Switzerland and in the Spanish Pyrenees. The first, simpler parameterization uses a commonly applied linear lapse rate. For the second parameterization, we first removed the obvious elevation gradient in mean snow depth, which revealed an additional correlation with the subgrid sky view factor. We evaluated domain-averaged snow depth derived with both parameterizations using flat field measurements nearby with the domain-averaged highly-resolved snow depth. This revealed an overall improved performance for the parameterization combining a power law elevation trend scaled with the subgrid parameterized sky view factor. We therefore suggest the parameterization could be used to assimilate flat field snow depth into coarse-scale snow model frameworks in order to improve coarse-scale snow depth estimates over complex topography.

Health effects of the September 2009 dust storm in Sydney, Australia: did emergency department visits and hospital admissions increase?

PubMed

Merrifield, Alistair; Schindeler, Suzanne; Jalaludin, Bin; Smith, Wayne

2013-04-16

During September 2009, a large dust storm was experienced in Sydney, New South Wales, Australia. Extremely high levels of particulate matter were recorded, with daily average levels of coarse matter (<10 μm) peaking over 11,000 μg/m3 and fine (<2.5 μm) over 1,600 μg/m3. We conducted an analysis to determine whether the dust storm was associated with increases in all-cause, cardiovascular, respiratory and asthma-related emergency department presentations and hospital admissions. We used distributed-lag Poisson generalized models to analyse the emergency department presentations and hospital admissions adjusted for pollutants, humidity, temperature and day of week and seasonal effects to obtain estimates of relative risks associated with the dust storm. The dust storm period was associated with large increases in asthma emergency department visits (relative risk 1.23, 95% confidence interval 1.10-1.38, p < 0.01), and to a lesser extent, all emergency department visits (relative risk 1.04, 95% confidence interval 1.03-1.06, p < 0.01) and respiratory emergency department visits (relative risk 1.20, 95% confidence interval 1.15-1.26, p < 0.01). There was no significant increase in cardiovascular emergency department visits (p = 0.09) or hospital admissions for any reason. Age-specific analyses showed the dust storm was associated with increases in all-cause and respiratory emergency department visits in the ≥65 year age group; the ≤5 year group had higher risks of all-cause, respiratory and asthma-related emergency department presentations. We recommend public health measures, especially targeting asthmatics, should be implemented during future dust storm events.

Revised Dst and the epicycles of magnetic disturbance: 1958-2007

USGS Publications Warehouse

Love, J.J.; Gannon, J.L.

2009-01-01

A revised version of the storm-time disturbance index Dst is calculated using hourly-mean magnetic-observatory data from four standard observatories and collected over the years 1958-2007. The calculation algorithm is a revision of that established by Sugiura et al., and which is now used by the Kyoto World Data Center for routine production of Dst. The most important new development is for the removal of solar-quiet variation. This is done through time and frequency-domain band-stop filtering - selectively removing specific Fourier terms approximating stationary periodic variation driven by the Earth's rotation, the Moon's orbit, the Earth's orbit around the Sun, and their mutual coupling. The resulting non-stationary disturbance time series are weighted by observatory-site geomagnetic latitude and then averaged together across longitudes to give what we call Dst5807-4SH. Comparisons are made with the standard Kyoto D st. Various biases, especially for residual solar-quiet variation, are identified in the Kyoto Dst, and occasional storm-time errors in the Kyoto Dst are noted. Using Dst5807-4SH, storms are ranked for maximum storm-time intensity, and we show that storm-occurrence frequency follows a power-law distribution with an exponential cutoff. The epicycles of magnetic disturbance are explored: we (1) map low-latitude local-time disturbance asymmetry, (2) confirm the 27-day storm-recurrence phenomenon using autocorrelation, (3) investigate the coupled semi-annual-diurnal variation of magnetic activity and the proposed explanatory equinoctial and Russell-McPherron hypotheses, and (4) illustrate the well-known solar-cycle modulation of storm-occurrence likelihood. Since Dst5807-4SH is useful for a variety of space physics and solid-Earth applications, it is made freely available to the scientific community.

Health effects of the September 2009 dust storm in Sydney, Australia: did emergency department visits and hospital admissions increase?

PubMed Central

2013-01-01

Background During September 2009, a large dust storm was experienced in Sydney, New South Wales, Australia. Extremely high levels of particulate matter were recorded, with daily average levels of coarse matter (<10 μm) peaking over 11,000 μg/m3 and fine (<2.5 μm) over 1,600 μg/m3. We conducted an analysis to determine whether the dust storm was associated with increases in all-cause, cardiovascular, respiratory and asthma-related emergency department presentations and hospital admissions. Methods We used distributed-lag Poisson generalized models to analyse the emergency department presentations and hospital admissions adjusted for pollutants, humidity, temperature and day of week and seasonal effects to obtain estimates of relative risks associated with the dust storm. Results The dust storm period was associated with large increases in asthma emergency department visits (relative risk 1.23, 95% confidence interval 1.10-1.38, p < 0.01), and to a lesser extent, all emergency department visits (relative risk 1.04, 95% confidence interval 1.03-1.06, p < 0.01) and respiratory emergency department visits (relative risk 1.20, 95% confidence interval 1.15-1.26, p < 0.01). There was no significant increase in cardiovascular emergency department visits (p = 0.09) or hospital admissions for any reason. Age-specific analyses showed the dust storm was associated with increases in all-cause and respiratory emergency department visits in the ≥65 year age group; the ≤5 year group had higher risks of all-cause, respiratory and asthma-related emergency department presentations. Conclusions We recommend public health measures, especially targeting asthmatics, should be implemented during future dust storm events. PMID:23587335

Artificial reproduction of magnetic fields produced by a natural geomagnetic storm increases systolic blood pressure in rats.

PubMed

Martínez-Bretón, J L; Mendoza, B; Miranda-Anaya, M; Durán, P; Flores-Chávez, P L

2016-11-01

The incidence of geomagnetic storms may be associated with changes in circulatory physiology. The way in which the natural variations of the geomagnetic field due to solar activity affects the blood pressure are poorly understood and require further study in controlled experimental designs in animal models. In the present study, we tested whether the systolic arterial pressure (AP) in adult rats is affected by simulated magnetic fields resembling the natural changes of a geomagnetic storm. We exposed adult rats to a linear magnetic profile that simulates the average changes associated to some well-known geomagnetic storm phases: the sudden commencement and principal phase. Magnetic stimulus was provided by a coil inductor and regulated by a microcontroller. The experiments were conducted in the electromagnetically isolated environment of a semi-anechoic chamber. After exposure, AP was determined with a non-invasive method through the pulse on the rat's tail. Animals were used as their own control. Our results indicate that there was no statistically significant effect in AP when the artificial profile was applied, neither in the sudden commencement nor in the principal phases. However, during the experimental period, a natural geomagnetic storm occurred, and we did observe statistically significant AP increase during the sudden commencement phase. Furthermore, when this storm phase was artificially replicated with a non-linear profile, we noticed a 7 to 9 % increase of the rats' AP in relation to a reference value. We suggested that the changes in the geomagnetic field associated with a geomagnetic storm in its first day could produce a measurable and reproducible physiological response in AP.

Hydrological Controls on Nutrient Concentrations and Fluxes in Agricultural Catchments

NASA Astrophysics Data System (ADS)

Petry, J.; Soulsby, C.

2002-12-01

This investigation into diffuse agricultural pollution and the hydrological controls that exert a strong influence on both nutrient concentrations and fluxes, was conducted in an intensively farmed lowland catchment in north-east Scotland. The study focuses on spatial and seasonal variations in nutrient concentrations and fluxes at the catchment scale, over a 15-month period. The water quality of the 14.5 km2 Newmills Burn catchment has relatively high nutrient levels with mean concentrations of NO3-N and NH3-N at 6.09 mg/l and 0.28 mg/l respectively. Average PO4-P concentrations are 0.06 mg/l. Over short timescales nutrient concentrations and fluxes are greatest during storm events when PO4-P and NH3-N are mobilised by overland flow in riparian areas, where soils have been compacted by livestock or machinery. Delivery of deeper soil water in subsurface storm flow, facilitated by agricultural under-drainage, produces a marked increase in NO3-N (6.9 mg/l) concentrations on the hydrograph recession limb. A more detailed insight into the catchment response to storm events, and in particular the response of the hydrological pathways which provide the main sources of runoff during storm events, was gained by sampling stream water at 2-hourly intervals during 5 events. End Member Mixing Analysis (EMMA) was carried out using event specific end-member chemistries to differentiate three catchment-scale hydrological pathways (overland flow, subsurface storm flow, groundwater flow) on the basis of observed Si and NO3-N concentrations in sampled source waters. Results show that overland flow generally dominates the storm peak and provides the main flow path by which P is transferred to stream channels during storm events, whilst subsurface storm flows usually dominate the storm hydrograph volumetrically and route NO3-rich soil water to the stream. The study shows that altering hydrological pathways in a catchment can have implications for nutrient management. Whilst buffer strips can reduce the delivery of NH3-N and PO4-P by overland flow to stream channels during storm events, the management of N-rich storm runoff as NO3 via sub-surface drains would require significant interference with the drainage network. This could have a negative impact on agricultural production in the catchment.

The Association between Dust Storms and Daily Non-Accidental Mortality in the United States, 1993–2005

PubMed Central

Crooks, James Lewis; Cascio, Wayne E.; Percy, Madelyn S.; Reyes, Jeanette; Neas, Lucas M.; Hilborn, Elizabeth D.

2016-01-01

Background: The impact of dust storms on human health has been studied in the context of Asian, Saharan, Arabian, and Australian storms, but there has been no recent population-level epidemiological research on the dust storms in North America. The relevance of dust storms to public health is likely to increase as extreme weather events are predicted to become more frequent with anticipated changes in climate through the 21st century. Objectives: We examined the association between dust storms and county-level non-accidental mortality in the United States from 1993 through 2005. Methods: Dust storm incidence data, including date and approximate location, are taken from the U.S. National Weather Service storm database. County-level mortality data for the years 1993–2005 were acquired from the National Center for Health Statistics. Distributed lag conditional logistic regression models under a time-stratified case-crossover design were used to study the relationship between dust storms and daily mortality counts over the whole United States and in Arizona and California specifically. End points included total non-accidental mortality and three mortality subgroups (cardiovascular, respiratory, and other non-accidental). Results: We estimated that for the United States as a whole, total non-accidental mortality increased by 7.4% (95% CI: 1.6, 13.5; p = 0.011) and 6.7% (95% CI: 1.1, 12.6; p = 0.018) at 2- and 3-day lags, respectively, and by an average of 2.7% (95% CI: 0.4, 5.1; p = 0.023) over lags 0–5 compared with referent days. Significant associations with non-accidental mortality were estimated for California (lag 2 and 0–5 day) and Arizona (lag 3), for cardiovascular mortality in the United States (lag 2) and Arizona (lag 3), and for other non-accidental mortality in California (lags 1–3 and 0–5). Conclusions: Dust storms are associated with increases in lagged non-accidental and cardiovascular mortality. Citation: Crooks JL, Cascio WE, Percy MS, Reyes J, Neas LM, Hilborn ED. 2016. The association between dust storms and daily non-accidental mortality in the United States, 1993–2005. Environ Health Perspect 124:1735–1743; http://dx.doi.org/10.1289/EHP216 PMID:27128449

Sediment characteristics of small streams in southern Wisconsin, 1954-59

USGS Publications Warehouse

Collier, Charles R.

1963-01-01

The results of investigations of the sediment and water discharge characteristics of Black Earth Creek, Mount Vernon Creek, and Yellowstone River from 1954 to 1959 and Dell Creek for 1958 and 1959 indicate large differences in annual runoff and sediment yields. The suspended-sediment discharge of Black Earth Creek averaged 3,260 tons per year or 71 tons per square mile : the annual yields ranged from 27 to 102 tons per square mile. The annual suspended-sediment yield of Mount Vernon Creek ranged from 48 to 171 tons per square mile and averaged 96 tons per square mile. The maximum daily discharge was 1,120 tons on April 1, 1960, during a storm which produced 67 percent of the suspended load for that water year and exceeded the discharge for the preceding 3 years. The sediment discharge of the Yellowstone River averaged 6,870 tons per year or 236 tons per square riffle. The maximum daily sediment discharge, 3,750 tons on April 1, 1959, occurred during a 14-day period of high flow during which the sediment discharge was 15,480 tons. In 1958 and 1959, Dell Creek had suspended-sediment yields of 4.7 and 26 tons per square mile of drainage area. The suspended sediment transported by Black Earth and Mount Vernon Creeks is about two-thirds clay and one-third silt. For Yellowstone River the particle-size distribution of the suspended sediment ranged from three-fourths clay and one-fourth silt during periods of low sediment discharge to one-third clay and two-thirds silt during high sediment discharges. For Dell Creek nearly all of the suspended sediment is clay, but the bed load is sand. The mean sediment concentration of storm runoff averaged two to three times more in the summer than in the winter. No significant changes with time occurred in the relation between storm runoff and sediment yield.

Dust deposition and ambient PM10 concentration in northwest China: spatial and temporal variability

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Xiao; Sharratt, Brenton; Chen, Xi; Wang, Zi-Fa; Liu, Lian-You; Guo, Yu-Hong; Li, Jie; Chen, Huan-Sheng; Yang, Wen-Yi

2017-02-01

Eolian dust transport and deposition are important geophysical processes which influence global bio-geochemical cycles. Currently, reliable deposition data are scarce in central and east Asia. Located at the boundary of central and east Asia, Xinjiang Province of northwestern China has long played a strategic role in cultural and economic trade between Asia and Europe. In this paper, we investigated the spatial distribution and temporal variation in dust deposition and ambient PM10 (particulate matter in aerodynamic diameter ≤ 10 µm) concentration from 2000 to 2013 in Xinjiang Province. This variation was assessed using environmental monitoring records from 14 stations in the province. Over the 14 years, annual average dust deposition across stations in the province ranged from 255.7 to 421.4 t km-2. Annual dust deposition was greater in southern Xinjiang (663.6 t km-2) than northern (147.8 t km-2) and eastern Xinjiang (194.9 t km-2). Annual average PM10 concentration across stations in the province varied from 100 to 196 µg m-3 and was 70, 115 and 239 µg m-3 in northern, eastern and southern Xinjiang, respectively. The highest annual dust deposition (1394.1 t km-2) and ambient PM10 concentration (352 µg m-3) were observed in Hotan, which is located in southern Xinjiang and at the southern boundary of the Taklamakan Desert. Dust deposition was more intense during the spring and summer than other seasons. PM10 was the main air pollutant that significantly influenced regional air quality. Annual average dust deposition increased logarithmically with ambient PM10 concentration (R2 ≥ 0.81). While the annual average dust storm frequency remained unchanged from 2000 to 2013, there was a positive relationship between dust storm days and dust deposition and PM10 concentration across stations. This study suggests that sand storms are a major factor affecting the temporal variability and spatial distribution of dust deposition in northwest China.

Effects of urban development on direct runoff to East Meadow Brook, Nassau County, Long Island, New York

USGS Publications Warehouse

Seaburn, G.E.

1969-01-01

The study described in this report is concerned with the effects of intensive urban development on direct runoff to East Meadow Brook, a southward-flowing stream in central Nassau County, N.Y., during the period 1937-66. The specific objectives of the study were (a) to relate indices of urban development to increases in the volume of annual direct runoff to the stream; (b) to compare hydrograph features at different periods during the transition of the drainage basin from rural to urban conditions; and (c) to compare the rainfall-runoff relations for periods before and after urban development.Periods of housing and street construction in the drainage basin correspond to three distinct periods of increased direct runoff after the base period 1937-43-namely, 1944-51, 1952-59, and 1960-62. During each period, the average annual direct runoff increased because of an increase in the area served by storm sewers that discharged into East Meadow Brook. The amount of land served by sewers increased from about 570 acres in 1943 to about 3,600 acres in 1962, or about 530 percent. During this same period, the average annual direct runoff increased from about 920 acre-feet per year to about 3,400 acre-feet per year, or about 270 percent.The shape of direct-runoff unit hydrographs of East Meadow Brook also changed during the period of study. The average peak discharge of a 1-hour-duration unit hydrograph increased from 313 cubic feet per second, for storms in 1937-43, to 776 cubic feet per second, for storms in 1960-62, or about 2.5 times. In addition, the widths of the unit hydrographs for 1960-62 at values of 50 and 75 percent of the peak discharge were 38 and 28 percent, respectively, the comparable widths of the unit hydrographs for 1937-43.An analysis of the rainfall-runoff relations for both preurban and urban conditions indicates that the direct runoff for both periods increased with the magnitude of the storm. However, the direct runoff during a period of urbanized conditions (1964- 66) was from 1.1 to 4.6 times greater than the corresponding runoff during the preurban period 1937-43, depending on the size of the individual storm.The volume of direct runoff from the parts of the subarea equipped with storm sewers that discharged into East Meadow Brook is estimated to have been roughly 3,000 acre-feet per year in 1960-62, or about 20 percent of the precipitation on those parts of the area.The increase in direct runoff probably represents a loss of ground-water recharge. However, because data changes in evapo-transpiration are insufficient and because the effects of recharge basins are unknown, adequate quantitative estimates of groundwater recharge can not be made.On the basis of the present zoning regulations and on assumption that an additional 320 acres in the Hempstead subarea will be serviced by storm sewers that discharge into East Meadow Brook, direct runoff from the subarea is expected to increase in the future to an estimated 4,000-4,500 acre-feet per year.

Seasonal Variation of Phytoplankton and Primary Production in the Thames River, Southeastern Connecticut

NASA Astrophysics Data System (ADS)

Wainright, S. C.

2016-02-01

A year-long study was performed to investigate seasonal changes in the phytoplankton biomass and primary production in the Thames River, a salt wedge estuary that empties into Long Island Sound in southeastern CT. Chlorophyll measurements were made on discrete filtered samples collected above and below the 1-3 m deep pycnocline at a 5-meter deep station. Surface chlorophyll concentrations, primarily from diatoms, averaged approx. 2 mg m-3, with maxima (up to 10 mg m-3) during summer months (Jun to Aug) and minima during October through March (as low as 0.3 mg m-3). The lower water layer had nearly the same annual average but a smaller range (0.7-3.3 mg m-3) and a winter/spring bloom (Jan-Apr) that was not seen in surface water. During most of the winter, chlorophyll concentrations were higher in the lower layer. Primary production, as measured by 13C uptake in bottle incubations, averaged 67 mgC m-3 h-1 in surface water [range 0.1 (Jan 2012) to 800 mgC m-3 h-1 (Aug 2011)], and 3 mgC m-3 h-1 [range 0.04 (Jan 2012) to 17 mgC m-3 h-1 (Aug 2011)] in the lower layer. On most occasions, deep water incubated near the surface had a higher primary production rate than surface water incubated at the surface; apparently the light-limited phytoplankton in the lower layer were released from light-limitation during these incubations. During the study period there were over a dozen heavy wind or heavy rain events, including Hurricane Irene in August and a freak Nor'easter snow storm in October 2011. Hurricane Irene was associated with a large decline in phytoplankton biomass and primary production. With significant storms as frequent as the rate of sampling, it is difficult to separate a "storm effect" from a background seasonal pattern. The study reveals that phytoplankton, especially those in the lower layer, are light-limited in the Thames River estuary, and that the effects of significant storm events are superimposed on significant seasonal variation.

Changing Water-Resources on Ile de la Gonave, Haiti

NASA Astrophysics Data System (ADS)

Troester, J. W.

2002-12-01

Ile de la Gonave is a 750-square-kilometer island off the western coast of Haiti. The island is composed of Eocene and Miocene limestones unconformably overlain by Pleistocene limestone. The highest elevation is 778 meters. Annual precipitation varies across the island because of the orographic effect and ranges from 800 to 1,400 millimeters. There is no surface water except immediately after large storms. Droughts, some extending for more than one year, and frequent crop failures due to droughts have been reported. Potential evaporation is estimated to be about 2,000 millimeters at the coast, but less at higher elevations. Consequently most rain is lost through evapotranspiration; recharge to the limestone aquifers apparently occurs only after large storms and is estimated to be about 4 percent of the mean annul precipitation based on a chloride mass balance. Depth to the water table ranges from less than 30 meters in the Eocene and Miocene limestones to over 60 meters in the 300-meter thick Quaternary limestone. Average annual precipitation at Port au-Prince (50 kilometers to the east and on the main island of Hispaniola) has decreased from about 1600 millimeters in 1860's to about 1300 mm in the 1950's. Precipitation data from Port-au-Prince after the 1950's are sporadic, making further comments about climate change difficult. Even without decreasing precipitation, which may be due in part to climate change or the deforestation of Haiti, the increasing population on Ile de la Gonave has and will continue to exacerbate the scarce water supply, particularly because of the small number of sources (springs, cave pools, and wells) where people can obtain water. Women take an average of almost three hours per day to travel an average of 2.5 kilometers (one-way) to obtain water for their families. Because of the difficulties in obtaining freshwater, the 100,000 inhabitants use an average of only 7 to 13 liters per person per day. Reconnaissance field analyses indicate that ground water in the interior of the island is of a calcium-bicarbonate type, while water at the coast is of a sodium-chloride type and has mixed with as much as 20 percent seawater. Tests for the presence of hydrogen sulfide-producing bacteria were negative in most drilled wells, but positive in most capped springs and positive in all springs, cave pools, and hand-dug wells, indicating contamination of most drinking-water sources. Widespread bacterial contamination of the water is not surprising, in that there are few latrines on the island and livestock grazes everywhere, enabling waste to be washed into the drinking water sources. The contaminated drinking water likely causes typhoid fever, which is frequently seen in the one hospital on the island.

Validation of foF2 and TEC Modeling During Geomagnetic Disturbed Times: Preliminary Outcomes of International Forum for Space Weather Modeling Capabilities Assessment

NASA Astrophysics Data System (ADS)

Shim, J. S.; Tsagouri, I.; Goncharenko, L. P.; Kuznetsova, M. M.

2017-12-01

To address challenges of assessment of space weather modeling capabilities, the CCMC (Community Coordinated Modeling Center) is leading the newly established "International Forum for Space Weather Modeling Capabilities Assessment." This presentation will focus on preliminary outcomes of the International Forum on validation of modeled foF2 and TEC during geomagnetic storms. We investigate the ionospheric response to 2013 Mar. geomagnetic storm event using ionosonde and GPS TEC observations in North American and European sectors. To quantify storm impacts on foF2 and TEC, we first quantify quiet-time variations of foF2 and TEC (e.g., the median and the average of the five quietest days for the 30 days during quiet conditions). It appears that the quiet time variation of foF2 and TEC are about 10% and 20-30%, respectively. Therefore, to quantify storm impact, we focus on foF2 and TEC changes during the storm main phase larger than 20% and 50%, respectively, compared to 30-day median. We find that in European sector, both foF2 and TEC response to the storm are mainly positive phase with foF2 increase of up to 100% and TEC increase of 150%. In North America sector, however, foF2 shows negative effects (up to about 50% decrease), while TEC shows positive response (the largest increase is about 200%). To assess modeling capability of reproducing the changes of foF2 and TEC due to the storm, we use various model simulations, which are obtained from empirical, physics-based, and data assimilation models. The performance of each model depends on the selected metrics, therefore, only one metrics is not enough to evaluate the models' predictive capabilities in capturing the storm impact. The performance of the model also varies with latitude and longitude.