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1

Convective storm measurement program planned  

NASA Astrophysics Data System (ADS)

An independent group of cloud physicists and chemists is planning a cooperative program on storm measurement for summer 1988. The program, which will be conducted in east-central Illinois, will focus on convective storms and is meant to provide as complete a description as possible of the dynamical, microphysical, and chemical processes that occur within precipitating convective clouds in a regionally polluted environment.

2

Mesoscale aspects of convective storms  

NASA Technical Reports Server (NTRS)

The structure, evolution and mechanisms of mesoscale convective disturbances are reviewed and observation techniques for "nowcasting" their nature are discussed. A generalized mesometeorological scale is given, classifying both low and high pressure systems. Mesoscale storms are shown often to induce strong winds, but their wind speeds are significantly less than those accompanied by submesoscale disturbances, such as tornadoes, downbursts, and microbursts. Mesoscale convective complexes, severe storm wakes, and flash floods are considered. The understanding of the evolution of supercells is essential for improving nowcasting capabilities and a very accurate combination of radar and satellite measurements is required.

Fujita, T. T.

1981-01-01

3

Convective storms in planetary atmospheres  

NASA Astrophysics Data System (ADS)

The atmospheres of the planets in the Solar System have different physical properties that in some cases can be considered as extreme when compared with our own planet's more familiar atmosphere. From the tenuous and cold atmosphere of Mars to the dense and warm atmosphere of Venus in the case of the terrestrial planets, to the gigantic atmospheres of the outer planets, or the nitrogen and methane atmosphere of Saturn's moon Titan, we can find a large variety of physical environments. The comparative study of these atmospheres provides a better understanding of the physics of a geophysical fluid. In many of these worlds convective storms of different intensity appear. They are analogous to terrestrial atmospheres fed by the release of latent heat when one of the gases in the atmosphere condenses and they are therefore called moist convective storms. In many of these planets they can produce severe meteorological phenomena and by studying them in a comparative way we can aspire to get a further insight in the dynamics of these atmospheres even beyond the scope of moist convection. A classical example is the structure of the complex systems of winds in the giant planets Jupiter and Saturn. These winds are zonal and alternate in latitude but their deep structure is not accessible to direct observation. However the behaviour of large--scale convective storms vertically extending over the "weather layer" allows to study the buried roots of these winds. Another interesting atmosphere with a rather different structure of convection is Titan, a world where methane is close to its triple point in the atmosphere and can condense in bright clouds with large precipitation fluxes that may model part of the orography of the surface making Titan a world with a methane cycle similar to the hydrological cycle of Earth's atmosphere.

Hueso, R.; Sánchez-Lavega, A.

2013-05-01

4

Concentration of Cloud Condensation Nuclei Before and After Convective Storms  

E-print Network

Chamber of a Cloud Condensation Nuclei Counter Relative Humidity > 100 % Determines the numberConcentration of Cloud Condensation Nuclei Before and After Convective Storms David Delene the concentration of Cloud Condensation Nuclei (CCN) change during the summer and fall in North Dakota Determine

Delene, David J.

5

Surface Outflows of Convective Storms.  

NASA Astrophysics Data System (ADS)

The vertical structure and surface characteristics of tropical maritime convective outflows over the Atlantic Ocean are investigated using instrumented tethered balloon and ship boom data collected during GATE. It is found that, while tropical maritime gust fronts are much less severe than those emanating from midlatitude continental storms, the updrafts induced at the gust fronts are sufficient to play a significant role in the initiation and maintenance of convection. A one-dimensional hydrostatic and incompressible model based upon the shallow water wave equations is developed. Axial symmetry is used to simulate outflows in a non-shearing environment, and slab symmetry is used to simulate unidirectional outflow. The data from two GATE gust front cases and one midlatitude squall line are used as input into the model and the results compared with the observations. The unidirectional model is capable of simulating the slope, depth and overall shape of both a mature and a decaying squall line gust front. The mean flow rates behind the model gust front compare well with horizontal velocities measured in the lower 1000 m. The model is used to construct a series of nomograms relating the depth of the gust front head to the origin and strength of the downdraft for various density differences and downdraft radii. It is found that cumulonimbi, which generate deep downdrafts over a large horizontal area and grow in an environment which encourages unidirectional outflow at the surface, produce the deepest gust fronts. They also require the weakest downdraft velocities to be maintained. From mechanical considerations alone, deep gust fronts propagating in a line produce the greatest amounts of lifting of boundary layer air, and hence play a significant role in the initiation and enhancement of convection.

Addis, Robert Paul

6

Interactions Between Convective Storms and Their Environment  

NASA Technical Reports Server (NTRS)

The ways in which intense convective storms interact with their environment are considered for a number of specific severe storm situations. A physical model of subcloud wind fields and vertical wind profiles was developed to explain the often observed intensification of convective storms that move along or across thermal boundaries. A number of special, unusually dense, data sets were used to substantiate features of the model. GOES imagery was used in conjunction with objectively analyzed surface wind data to develop a nowcast technique that might be used to identify specific storm cells likely to become tornadic. It was shown that circulations associated with organized meso-alpha and meso-beta scale storm complexes may, on occasion, strongly modify tropospheric thermodynamic patterns and flow fields.

Maddox, R. A.; Hoxit, L. R.; Chappell, C. F.

1979-01-01

7

Principles of Convection III: Shear and Convective Storms  

NSDL National Science Digital Library

This module discusses the role of wind shear in the structure and evolution of convective storms. Using the concept of horizontal vorticity, the module demonstrates how shear enhances uplift, leading to longer-lived supercell and multicell storms. The module also explores the role of shear in the development of mesoscale convective systems, including bow echoes and squall lines. Most of the material in this module previously appeared in the COMET modules developed with Dr. Morris Weisman. This version includes a concise summary for quick reference and a final exam to test your knowledge. The module comes with audio narration, rich graphics, and a companion print version.

2014-09-14

8

Comparison of TEC response for summer and winter geomagnetic storms  

Microsoft Academic Search

We investigated the response of TEC over Europe to summer and winter geomagnetic storms using observations of European GPS network. The spatial and temporal evolution of TEC during storm was analyzed on base of TEC maps which created with 1 hour interval in latitudinal range of 35° -70° N. Comparison of storm effects was carried out for severe geomagnetic storm

Irk Shagimuratov; Galina Yakimova; Irina Zakharenkova; Andrzej Krankowski

2008-01-01

9

A Convective Storm Matrix: Buoyancy/Shear Dependencies  

NSDL National Science Digital Library

In order to help forecasters build a strategy for anticipating convective storm structures, their evolution, and the potential for severe weather, A Convective Storm Matrix provides learners the opportunity for extensive exploration of the relationship between a storm's environment and its structure. The matrix is composed of 54 four-dimensional numerical simulations based on the interactions of 16 different hodographs and 4 thermodynamic profiles. By comparing animated displays of these simulations, learners are able to discern the influences of varying buoyancy and vertical wind shear profiles on storm structure and evolution. A series of questions guides the exploration and helps to reveal key storm/environment relationships evident in the matrix. A synopsis of the physical processes that control storm structure, as well as the current conceptual models of key convective storms types, is included for reference. Subject matter expects for A Convective Storm Matrix: Buoyancy/Shear Dependencies include Mr. Steve Keighton, Mr. Ed Szoke, and Dr. Morris Weisman. Note: This module was originally published on CD-ROM in March 1996 (v1.1) and re-released in 2001 as v1.3 for Microsoft Windows users only. CD-ROM version 1.3 works fairly well with Windows 98/ME/NT4/2000 but has reported to be problematic with Windows XP. Users of version 1.1 should obtain the patch located at http://www.comet.ucar.edu/help/ModuleSupport/matrix_problem.htm or use the new, Web-based module.

2014-09-14

10

Validation of satellite-based CI detection of convective storms via backward trajectories  

NASA Astrophysics Data System (ADS)

Within this study, the rapid development and evolution of several severe convective events is investigated based on geostationary satellite images, and is related to previous findings on suitable detection thresholds for convective initiation. Nine severe events have been selected that occurred over Central Europe in summer 2012, and have been classified into the categories supercell, mesoscale convective system, frontal system and orographic convection. The cases are traced backward starting from the fully developed convective systems to its very beginning initial state using ECMWF data with 0.5 degree spatial resolution and 3h temporal resolution. For every case the storm life cycle was quantified through the storm's infrared (IR) brightness temperatures obtained from Meteosat Second Generation SEVIRI with 5 min temporal resolution and 4.5 km spatial resolution. In addition, cloud products including cloud optical thickness, cloud phase and effective droplet radius have been taken into account. A semi-automatic adjustment of the tracks within a search box was necessary to improve the tracking accuracy and thus the quality of the derived life-cycles. The combination of IR brightness temperatures, IR temperature time trends and satellite-based cloud products revealed different stages of storm development such as updraft intensification and glaciation well in most casesconfirming previously developed CI criteria from other studies. The vertical temperature gradient between 850 and 500 hPa, the Total-Totals-Index and the storm-relative helicity have been derived from ECMWF data and were used to characterize the storm synoptic environment. The results suggest that the storm-relative helicity also influences the life time of convective storms over Central Europe confirming previous studies. Tracking accuracy has shown to be a crucial issue in our study and a fully automated approach is required to enlarge the number of cases for significant statistics.

Dietzsch, Felix; Senf, Fabian; Deneke, Hartwig

2013-04-01

11

Severe Deep Moist Convective Storms: Forecasting and Mitigation  

Microsoft Academic Search

Small-scale (2-20 km) circulations, termed 'severe deep moist convective storms', account for a disproportionate share of the world's insured weather-related losses. Spatial frequency maximums of severe convective events occur in South Africa, India, Mexico, the Caucasus, and Great Plains\\/Prairies region of North America, where the maximum tornado frequency occurs east of the Rocky Mountains. Interest in forecasting severe deep moist

David L. Arnold

2008-01-01

12

Horizontal dipoles of potential vorticity generated by convective storms  

NASA Astrophysics Data System (ADS)

The structure and dynamics of potential vorticity (PV) anomalies generated by convective storms is investigated both theoretically and in a numerical case study. Linear theory suggests that if the storm-induced heating is on a sufficiently small scale relative to the Rossby radius of deformation and the environment contains moderate vertical wind shear of order 1 m/s/km, then the dominant mode of PV is a horizontally oriented dipole. The horizontal dipoles are typically of larger magnitude e.g., 10 PVU than the vertical dipoles that have been studied extensively throughout the literature. Furthermore, the horizontal PV dipoles are realised almost entirely as relative vorticity anomalies on a time scale of order tens of minutes after the heating. The analysis of horizontal PV dipoles offers a new perspective on vorticity dynamics of individual convective cells, implying that moist processes play a role in the maintenance of small scale vortices in the storm environment.

Chagnon, J.; Gray, S. L.

2009-04-01

13

Extreme Summer Convection in South America ULRIKE ROMATSCHKE  

E-print Network

Extreme Summer Convection in South America ULRIKE ROMATSCHKE University of Washington, Seattle for extreme summer convection over South America. The three- dimensional reflectivity field is analyzed related to continental heating. 1. Introduction South America features some of the most extreme convective

Houze Jr., Robert A.

14

The Simulation of Three-Dimensional Convective Storm Dynamics  

Microsoft Academic Search

A new three-dimensional cloud model has been developed for investigating the dynamic character of convective storms. This model solves the compressible equations of motion using a splitting procedure which provides numerical efficiency by treating the sound wave modes separately. For the subgrid turbulence processes, a time-dependent turbulence energy equation is solved which depends on local buoyancy, shear and dissipation. First-order

Joseph B. Klemp; Robert B. Wilhelmson

1978-01-01

15

A-Train Observations of Deep Convective Storm Tops  

NASA Technical Reports Server (NTRS)

The paper highlights simultaneous observations of tops of deep convective clouds from several space-borne instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Aqua satellite, Cloud Profiling Radar (CPR) of the CloudSat satellite, and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) flown on the CALIPSO satellite. These satellites share very close orbits, thus together with several other satellites they are referred to as the "A-Train" constellation. Though the primary responsibility of these satellites and their instrumentation is much broader than observations of fine-scale processes atop convective storms, in this study we document how data from the A-Train can contribute to a better understanding and interpretation of various storm-top features, such as overshooting tops, cold-U/V and cold ring features with their coupled embedded warm areas, above anvil ice plumes and jumping cirrus. The relationships between MODIS multi-spectral brightness temperature difference (BTD) fields and cloud top signatures observed by the CPR and CALIOP are also examined in detail to highlight the variability in BTD signals across convective storm events.

Setvak, Martin; Bedka, Kristopher; Lindsey, Daniel T.; Sokol, Alois; Charvat, Zdenek; Stastka, Jindrich; Wang, Pao K.

2013-01-01

16

Modes of isolated, severe convective storm formation along the dryline  

SciTech Connect

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 a 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.

Bluestein, H.B.; Parker, S.S. (Univ. of Oklahoma, Norman (United States))

1993-05-01

17

Late-summer Martian Dust Storm  

NASA Technical Reports Server (NTRS)

This is an image of Mars taken from orbit by the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI). The Red Planet's polar ice-cap is in the middle of the image. Captured in this image is a 37,000 square-kilometer (almost 23,000 miles) dust storm that moved counter-clockwise through the Phoenix landing site on Oct 11, 2008, or Sol 135 of the mission.

Viewing this image as if it were the face of a clock, Phoenix is shown as a small white dot, located at about 10 AM. The storm, which had already passed over the landing site earlier in the day, is located at about 9:30 AM.

2008-01-01

18

Characteristics of Extreme Summer Convection over equatorial America and Africa  

NASA Astrophysics Data System (ADS)

Fourteen years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) version 7 data for June-August show the temporal and spatial characteristics of extreme convection over equatorial regions of the American and African continents. We identify three types of extreme systems: storms with deep convective cores (contiguous convective 40 dBZ echoes extending ?10 km in height), storms with wide convective cores (contiguous convective 40 dBZ echoes with areas >1,000 km2) and storms with broad stratiform regions (stratiform echo >50,000 km2). European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis is used to describe the environmental conditions around these forms of extreme convection. Storms with deep convective cores occur mainly over land: in the equatorial Americas, maximum occurrence is in western Mexico, Northern Colombia and Venezuela; in Africa, the region of maximum occurrence is a broad zone enclosing the central and west Sudanian Savanna, south of the Sahel region. Storms with wide convective radar echoes occur in these same general locations. In the American sector, storms with broad stratiform precipitation regions (typifying robust mesoscale convective systems) occur mainly over the eastern tropical Pacific Ocean and the Colombia-Panama bight. In the African sector, storms with broad stratiform precipitation areas occur primarily over the eastern tropical Atlantic Ocean near the coast of West Africa. ECMWF reanalyses show how the regions of extreme deep convection associated with both continents are located mainly in regions affected by diurnal heating and influenced by atmospheric jets in regions with strong humidity gradients. Composite analysis of the synoptic conditions leading to the three forms of extreme convection provides insights into the forcing mechanisms in which these systems occur. These analyses show how the monsoonal flow directed towards the Andes slopes is mainly what concentrates the occurrence of extreme cases over tropical America. Over Africa the monsoon is also important in modulating the occurrence of extreme convection; however, diurnal heating and the passage of African Easterly Waves are of primary importance in distributing the extreme convection zonally across the tropical African savannas.

Zuluaga, M. D.; Houze, R.

2013-12-01

19

Empirical reconstruction of storm-time steady magnetospheric convection events  

NASA Astrophysics Data System (ADS)

We investigate the storm-scale morphology of the magnetospheric magnetic field as well as underlying distributions of electric currents, equatorial plasma pressure and entropy for four Steady Magnetospheric Convection (SMC) events that occurred during the May 2000 and October 2011 magnetic storms. The analysis is made using the empirical geomagnetic field model TS07D, in which the structure of equatorial currents is not predefined and it is dictated by data. The model also combines the strengths of statistical and event-oriented approaches in mining data for the reconstruction of the magnetic field. The formation of a near-Earth minimum of the equatorial magnetic field in the midnight sector is inferred from data without ad hoc assumptions of a special current system postulated in earlier empirical reconstructions. In addition, a new SMC class is discovered where the minimum equatorial field is substantially larger and located closer to Earth. The magnetic field tailward of the minimum is also much larger, and the corresponding region of accumulated magnetic flux may occupy a very short tail region. The equatorial current and plasma pressure are found to be strongly enhanced far beyond geosynchronous orbit and in a broad local time interval covering the whole nightside region. This picture is consistent with independent recent statistical studies of the SMC pressure distributions, global MHD and kinetic RCM-E simulations. Distributions of the flux tube volume and entropy inferred from data reveal different mechanisms of the magnetotail convection crisis resolution for two classes of SMC events.

Stephens, G. K.; Sitnov, M. I.; Kissinger, J.; Tsyganenko, N. A.; McPherron, R. L.; Korth, H.; Anderson, B. J.

2013-12-01

20

Empirical reconstruction of storm time steady magnetospheric convection events  

NASA Astrophysics Data System (ADS)

We investigate the storm-scale morphology of the magnetospheric magnetic field as well as underlying distributions of electric currents, equatorial plasma pressure, and entropy for four steady magnetospheric convection (SMC) events that occurred during the May 2000 and October 2011 magnetic storms. The analysis is made using the empirical geomagnetic field model TS07D, in which the structure of equatorial currents is not predefined and it is dictated by data. The model also combines the strengths of statistical and event-oriented approaches in mining data for the reconstruction of the magnetic field. The formation of a near-Earth minimum of the equatorial magnetic field in the midnight sector is inferred from data without ad hoc assumptions of a special current system postulated in earlier empirical reconstructions. In addition, a new SMC class is discovered where the minimum equatorial field is substantially larger and located closer to Earth. The magnetic field tailward of the minimum is also much larger, and the corresponding area of accumulated magnetic flux may occupy a very short tail region. The equatorial current and plasma pressure are found to be strongly enhanced far beyond geosynchronous orbit and in a broad local time interval covering the whole nightside region. This picture is consistent with independent recent statistical studies of the SMC pressure distributions, global MHD, and kinetic Rice Convection Model-Equilibrium (RCM-E) simulations. Distributions of the flux tube volume and entropy inferred from data reveal different mechanisms of the magnetotail convection crisis resolution for two classes of SMC events.

Stephens, G. K.; Sitnov, M. I.; Kissinger, J.; Tsyganenko, N. A.; McPherron, R. L.; Korth, H.; Anderson, B. J.

2013-10-01

21

Plasmapause Convects to the Magnetopause During Halloween Solar Storm  

NSDL National Science Digital Library

The plasmasphere is a region of ionospheric plasma which co-rotates with the Earth, carried by the magnetic field lines. The plasmapause marks the outer boundary of this region. This colder plasma is more easily moved by the electric fields created by strong solar storms. In the Halloween 2003 event, these fields convected some of the cold plasma out to the magnetopause (grey, semi-transparent surface) and reduced the size of the cold plasma region near the Earth. For this visualization, the 3-dimensional structure was constructed from the equatorial profile of the plasmapause (as measured by IMAGE-EUV data) by extending the region along field lines of a simple dipole field.

Tom Bridgman

2004-12-15

22

Changes in concentration of Alternaria and Cladosporium spores during summer storms  

NASA Astrophysics Data System (ADS)

Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly concentrations of atmospheric Alternaria and Cladosporium spores on days with summer storms in Szczecin (Poland) based on meteorological conditions. For this study we have chosen all days of June, July and August (2004-2009) with convective thunderstorms. There were statistically significant relationships between spore concentration and meteorological parameters: positive for air temperature and ozone content while negative for relative humidity. In general, before a thunderstorm, air temperature and ozone concentration increased, which was accompanied by a considerable increase in spore concentration. During and after a storm, relative humidity increased while both air temperature ozone concentration along with spore concentrations decreased. Artificial neural networks (ANN) were used to assess forecasting possibilities. Good performance of ANN models in this study suggest that it is possible to predict spore concentrations from meteorological variables 2 h in advance and, thus, warn people with spore-related asthma symptoms about the increasing abundance of airborne fungi on days with storms.

Grinn-Gofro?, Agnieszka; Strzelczak, Agnieszka

2013-09-01

23

Changes in concentration of Alternaria and Cladosporium spores during summer storms.  

PubMed

Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly concentrations of atmospheric Alternaria and Cladosporium spores on days with summer storms in Szczecin (Poland) based on meteorological conditions. For this study we have chosen all days of June, July and August (2004-2009) with convective thunderstorms. There were statistically significant relationships between spore concentration and meteorological parameters: positive for air temperature and ozone content while negative for relative humidity. In general, before a thunderstorm, air temperature and ozone concentration increased, which was accompanied by a considerable increase in spore concentration. During and after a storm, relative humidity increased while both air temperature ozone concentration along with spore concentrations decreased. Artificial neural networks (ANN) were used to assess forecasting possibilities. Good performance of ANN models in this study suggest that it is possible to predict spore concentrations from meteorological variables 2 h in advance and, thus, warn people with spore-related asthma symptoms about the increasing abundance of airborne fungi on days with storms. PMID:23161270

Grinn-Gofro?, Agnieszka; Strzelczak, Agnieszka

2013-09-01

24

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project  

NASA Astrophysics Data System (ADS)

The Convective Storm Initiation Project (CSIP) took place during the summers of 2004 and 2005, centred on the research radar at Chilbolton, UK. Precursors to convective precipitation were studied, using a comprehensive and broad-based range of fieldwork and modelling. The principal aim of CSIP was the detection of the primary and secondary initiation of convective cells. The Universities Facility for Atmospheric Measurements (UFAM) Cessna 182 was used to map temperature and humidity fields over a broad area within and beyond the Chilbolton radar beam. Additionally, air motion was measured using a new turbulence probe, the AIMMS20AQ. The performance of the probe is critically appraised, based on calibrations, test flights and data flights flown during CSIP intensive operating periods. In general, the probe performed well, although some aspects require more careful data interpretation which we describe in detail.

Beswick, K. M.; Gallagher, M. W.; Webb, A. R.; Norton, E. G.; Perry, F.

2007-03-01

25

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project  

NASA Astrophysics Data System (ADS)

The Convective Storm Initiation Project (CSIP) took place during the summers of 2004 and 2005, centred on the research radar at Chilbolton, UK. Precursors to convective precipitation were studied, using a comprehensive and broad-based range of fieldwork and modelling. The principal aim of CSIP was the detection of the primary and secondary initiation of convective cells. The Universities Facility for Atmospheric Measurements (UFAM) Cessna 182 was used to map temperature and humidity fields over a broad area within and beyond the Chilbolton radar beam. Additionally, air motion was measured using a new turbulence probe, the AIMMS20AQ. The performance of the probe is critically appraised, based on calibrations, test flights and data flights flown during CSIP intensive operating periods. In general, the probe performed well, although some aspects require more careful data interpretation which we describe in detail.

Beswick, K. M.; Gallagher, M. W.; Webb, A. R.; Norton, E. G.; Perry, F.

2008-09-01

26

Atmospheric infrasound observed during intense convective storms on 9-10 July 2011  

NASA Astrophysics Data System (ADS)

Atmospheric infrasound of frequencies 0.1-4 Hz observed in Central Europe during convective storms on 9-10 July 2011 from 21:00 to 02:57 UT was analysed. Azimuth of signal arrival followed positions of the convective storms passing over the region of measurements from south-west to north-east. Significant variations in azimuths of signal arrival (up to 105°) occurred periodically between 21:30 and 23:00 UT, at the time of maximum development of convective storms. Sprites (discharges in the mesosphere) seem to be potential sources of these infrasound signals. Stable infrasound arrivals were observed between 02:00 and 02:57 UT from direction where abating convective storms were located.

Sindelarova, T.; Chum, J.; Skripnikova, K.; Base, J.

2015-01-01

27

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON  

E-print Network

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON. 2004; Givati and Rosenfeld 2004; Molders and Olson 2004; Jirak and Cotton 2006); 2) increased surface

Collett Jr., Jeffrey L.

28

Atmospheric structure and variability in areas of convective storms determined from 3-h rawinsonde data  

NASA Technical Reports Server (NTRS)

The structure and variability of the atmosphere in areas of radar-observed convection were established by using 3-h rawinsonde and surface data from NASA's second Atmospheric Variability Experiment. Convective activity was shown to exist in areas where the low and middle troposphere is moist and the air is potentially and convectively unstable and has upward motion, in combination with positive moisture advection, at either the surface or within the boundary layer. The large variability of the parameters associated with convective storms over time intervals less than 12 h was also demonstrated so as to possibly produce a change in the probability of convective activity by a factor of 8 or more in 3 h. Between 30 and 60 percent of the total changes in parameters associated with convective activity over a 12-h period were shown to take place during a 3-h period. These large changes in parameters are related to subsynoptic-scale systems that often produce convective storms.

Wilson, G. S.; Scoggins, J. R.

1976-01-01

29

Observed and Simulated Radiative and Microphysical Properties of Tropical Convective Storms  

NASA Technical Reports Server (NTRS)

Increases in the ice content, albedo and cloud cover of tropical convective storms in a warmer climate produce a large negative contribution to cloud feedback in the GISS GCM. Unfortunately, the physics of convective upward water transport, detrainment, and ice sedimentation, and the relationship of microphysical to radiative properties, are all quite uncertain. We apply a clustering algorithm to TRMM satellite microwave rainfall retrievals to identify contiguous deep precipitating storms throughout the tropics. Each storm is characterized according to its size, albedo, OLR, rain rate, microphysical structure, and presence/absence of lightning. A similar analysis is applied to ISCCP data during the TOGA/COARE experiment to identify optically thick deep cloud systems and relate them to large-scale environmental conditions just before storm onset. We examine the statistics of these storms to understand the relative climatic roles of small and large storms and the factors that regulate convective storm size and albedo. The results are compared to GISS GCM simulated statistics of tropical convective storms to identify areas of agreement and disagreement.

DelGenio, Anthony D.; Hansen, James E. (Technical Monitor)

2001-01-01

30

Environments that Produce "Extreme" Convective Storm Behavior: Results from a Large Numerical Modeling Study  

NASA Astrophysics Data System (ADS)

The behavior of a convective storm is closely related to its ambient environment. In this paper, we explore the environments that produce "extreme" storm behaviors, namely, strong surface winds; copious amounts of precipitation (rain and hail); and strong low level rotation, related to tornadoes. The study focuses on a set of over 200 cloud-resolving numerical simulations, with the dominant storm in each simulation tracked and analyzed for up to 2 h. It is found that different environmental conditions are needed to produce different types of "extreme" behavior. For example, increased convective available potential energy (CAPE) typically causes the amount of hail produced to increase, but has relatively little effect on surface precipitation rates. The ambient precipitable water (PW) is found to have a greater impact on heavy rainfall than does CAPE. The storms with the strongest low level rotation exist in environments with low cloud bases and low, continental values of PW, however storms that produce large swaths of strong outflow winds at the surface occur in environments with deeper sub-cloud layers and enhanced PW. These and other relationships will be discussed. An understanding of these atmospheric conditions and how they relate to storm behavior will be critical for future study of long-term temporal trends in the distribution of convection-driven high impact weather.

Kirkpatrick, C.; McCaul, E. W., Jr.

2010-12-01

31

Upper tropospheric conditions in relation to the cloud top features of 15 August 2010 convective storms  

NASA Astrophysics Data System (ADS)

This study focuses on 15 August 2010, when many severe convective storms occurred over parts of central and Eastern Europe, with some of these exhibiting various interesting cloud-top characteristics observed by weather satellites. The importance of the phenomena of cold-U and cold-ring features in the infrared brightness temperature enhanced imagery stems from the fact that storms exhibiting these features are very often accompanied by severe weather. Therefore, besides the general description of the atmospheric conditions in the area, we seek possible reasons for the different cloud-top appearance of these storms from the perspective of Meteosat Second Generation and polar-orbiting weather satellites. Two main issues are discussed in this paper - the unusually warm appearance of the cloud-top of the “Prague hailstorm” and the presence of cold-ring and cold-U shaped storms in close proximity to the warmer “Prague hailstorm”. Both of these issues prove that the storm top appearance is very sensitive to the upper tropospheric and lower stratospheric conditions, with the first one strongly reflecting variations in the tropopause height due to the presence of the jet-stream over the region. The second topic addresses the strength of the storm relative upper level winds as a major discriminator between the cold-U and cold-ring storm top categories. Due to the above mentioned facts, 15 August 2010 was selected as one of the prime cases of interest for the Convection Working Group.

Pú?ik, Tomáš; Valachová, Michaela; Zacharov, Petr

2013-04-01

32

Documentary evidence on strong winds related to convective storms in the Czech Republic since AD 1500  

Microsoft Academic Search

This article summarizes information about the occurrence of strong winds connected with convective storms in the Czech Republic for the last 500 years obtained on the basis of the study of historical documentary sources. Documentary evidence about strong winds is characterized with respect to its advantages and drawbacks. Principles are stated for setting up the database of strong winds and

Petr Dobrovolný; Rudolf Brázdil

2003-01-01

33

A Method for Diagnosing the Sources of Infrasound in Convective Storm Simulations DAVID A. SCHECTER  

E-print Network

A Method for Diagnosing the Sources of Infrasound in Convective Storm Simulations DAVID A. SCHECTER July 2011) ABSTRACT This paper presents a convenient method for diagnosing the sources of infrasound are carried out to illustrate the infrasound of Suu and Sm. Moreover, the diagnostic method is applied

Schecter, David

34

The role of near surface outflow in maintaining convective activity. [in storms  

NASA Technical Reports Server (NTRS)

Continuous measurements of horizontal velocity, temperature and humidity at the surface over a dense network of stations were used to examine the behavior, at the surface, of a large number of convective storms. Feedback between storm outflow at the surface and the generation of convective cells is demonstrated. The outflow is shown in the surface divergence fields once rain begins, with characteristics common to storms in distinctly different meteorological environments, such as summertime Florida and Illinois. This commencement precedes the occurence of rainfall and radar echo in the location of the cell by some tens of minutes up to more than 100 mins. Given surface measurements with a spacing of no more than 10 km, the direction of propagation, timing of the future occurence of rainfall and the intensity of the rainfall generated in the cell can be determined.

Garstang, M.; Cooper, H. J.

1981-01-01

35

Thunderstorms In some storms, convection produces lightning and thunder. Although storm electrification can occur in a variety of circumstances, most thunderstorms  

E-print Network

1 Thunderstorms In some storms, convection produces lightning and thunder. Although storm and atmospheric haze, but their presence is made evident by lightning and thunder. Because such clouds can be very updraft and downdraft, the heaviest precipitation, and the most frequent lightning. Finally, the cell

Doswell III, Charles A.

36

Analysis of Severe Convective Storms Observed by Radar  

Microsoft Academic Search

A survey of thunderstorms observed during 1956 by CPS-9 radar from Blue Hill (Milton, Massachusetts) revealed a high frequency of hail occurrence (as reported by a regional network of cooperative observers) in storms in which the radar echo attained high altitudes and large values of radar reflectivity factor. Hail frequencies are related to these criteria, and to the single criterion

Ralph J. Donaldson Jr.

1958-01-01

37

Sensitivity of Severe Convective Storms to Soil Moisture and Lower Atmospheric Water Vapor  

NASA Astrophysics Data System (ADS)

Numerous studies have examined the sensitivity of the atmospheric state to soil moisture on time scales of up to a day. Dry line intensity, lower tropospheric water vapor content, and precipitation have all been shown through modeling studies to be affected by modest perturbations to upstream soil moisture content and subsequent lower atmospheric water vapor. Since all of these aspects could be associated with convection, a high-impact forecast event that exhibits rapid nonlinear error growth, it is reasonable to expect that irrigation practices might influence severe convective storms. Understanding the link between soil moisture and specific convective elements could have broad implications for severe weather forecasting, and could reveal the degree to which irrigation-induced storm-scale inadvertent weather modification exists. This work examines the sensitivity to soil moisture and lower atmospheric water vapor content of a severe convective storm that struck Moore, Oklahoma, USA on May 20th, 2013, killing 24 people. While adjoint sensitivity analysis that employs the tangent linear version of a numerical weather prediction model might be used to examine convective sensitivities to soil moisture, the strong nonlinearity associated with these events likely renders this technique inaccurate. Alternatively, the approach here utilizes backward trajectory analysis to identify the regions up to a day prior to which the storm might be sensitive. Once the regions are identified, an ensemble of model forecasts is created by varying initial soil moisture to reveal the degree to which perturbations must be made to influence the downstream storm. Subsequent comparisons are made between the required soil moisture perturbations and realistic soil water values added through irrigation.

Ancell, Brian; Nauert, Christian

2014-05-01

38

The DYMECS project: The Dynamical and Microphysical Evolution of Convective Storms  

NASA Astrophysics Data System (ADS)

A new frontier in weather forecasting is emerging by operational forecast models now being run at convection-permitting resolutions at many national weather services. However, this is not a panacea; significant systematic errors remain in the character of convective clouds and rainfall distributions. The DYMECS project (Dynamical and Microphysical Evolution of Convective Storms) is taking a fundamentally new approach to evaluate and improve such models: rather than relying on a limited number of cases, which may not be representative, we have gathered a large database of 3D storm structures on 40 convective days using an automated storm-tracking and scan-scheduling algorithm for the high resolution Chilbolton radar in southern England. These structures have been related to storm life-cycles derived by tracking features in the rainfall from the UK radar network, and compared statistically to simulated reflectivity fields from multiple versions of the Met Office model, varying horizontal grid length between 1.5 km and 100 m, and changing the sub-grid mixing and microphysics schemes. We also evaluated the scale and intensity of convective updrafts using a new radar technique. We find that the horizontal size of simulated convective clouds and the updrafts within them decreases with decreasing grid lengths down to 200 m, below which no further decrease is found. Comparison with observations reveals that at these resolutions, updrafts are about the right size (around 2 km across), but the clouds are typically too narrow and rain too intense (in both cases by around a factor of two), while progressing through their lifecycle too slowly. The scale error may be remedied by artificially increasing mixing length, but the microphysics scheme has little effect on either scale or intensity.

Stein, Thorwald; Hogan, Robin; Hanley, Kirsty; Nicol, John; Plant, Robert; Lean, Humphrey; Clark, Peter; Halliwell, Carol

2014-05-01

39

Analysis of Severe Convective Storms Observed by Radar-Ii  

Microsoft Academic Search

The frequency of hail occurrence in New England thunderstorms during 1956 and 1957 was directly related to the maximum heights and maximum reflectivity factors of the thunderstorm echoes measured by CPS-9 radar. Hail frequencies in excess of 33 per cent occurred in storms with echo heights above 46,000 to 49,000 ft, with little dependence on reflectivity. Higher hail frequencies were

Ralph J. Donaldson Jr.

1959-01-01

40

Submicron Aerosol Transport and Aging by Convective Storms During the DC3 Campaign  

NASA Astrophysics Data System (ADS)

The Deep Convective Clouds and Chemistry (DC3) study was a multiagency sponsored aircraft campaign to characterize the contribution of strong convective spring storms over the Midwestern US to the chemistry of the upper troposphere (UT), both by transport of pollutants from the boundary layer to the UT and by acting as a fast, multiphase chemical reactor. Over twenty research flights targeting storms in Eastern Colorado, Southern Oklahoma and Alabama as well as outflow from past storms in those regions were conducted out of Salina, KS using the NCAR/NSF G-V and the NASA DC-8 research aircraft. An Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) was deployed on board of the NASA DC-8 during DC3. Chemically speciated submicron aerosol mass concentrations were measured with 1 second time resolution. Size-resolved composition data were acquired with a lower frequency (~1 min). While overall, measured aerosol concentrations in the UT were very low and consistent with background sulfate, several stronger storms sampled during DC3 resulted in significant concentrations of (aged) organic and nitrate aerosols at altitudes >8 km. A detailed analysis of the concentration and chemical properties of the organic fraction of the aerosol in the storm inflow and UT aerosol is used to determine to what extent the aging signature is due to selective transport/deposition of particles from the boundary layer vs in-cloud formation and/or processing of those particles. A special case was the flight on Jun 22nd, 2012, when fresh smoke from the High Park Fire near Ft. Collins,CO was entrained into the updraft of a storm, resulting in organic UT loadings in excess of 50 ug/m3. Here it was again possible to sample the fresh smoke plume prior to entering the storm cloud and hence observe the chemical evolution of the smoke as it was lofted by the storm.

Campuzano Jost, P.; Day, D. A.; Palm, B. B.; Ortega, A. M.; Hayes, P. L.; Jimenez, J. L.

2012-12-01

41

Simulating supercell thunderstorms in a convective boundary layer: Effects on storm and boundary layer properties  

NASA Astrophysics Data System (ADS)

Nearly all previous numerical simulations of supercell thunderstorms have neglected surface uxes of heat, moisture, and momentum as well as horizontal inhomogeneities in the near-storm environment from resulting dry boundary layer convection. This investigation uses coupled radiation and land-surface schemes within an idealized cloud model to identify the effects of organized boundary layer convection in the form of horizontal convective rolls (HCRs) on the strength, structure, and evolution of simulated supercell thunderstorms. The in uence of HCRs and the importance of their orientation relative to storm motion is tested by comparing simulations with a convective boundary layer (CBL) against those with a horizontally homogeneous base state having the same mean environment. The impact of anvil shading on the CBL is tested by comparing simulations with and without the effects of clouds in the radiative transfer scheme. The results of these simulations indicate that HCRs provide a potentially important source of environmental vertical vorticity in the sheared, near-storm boundary layer. These vorticity perturbations are amplified both beneath the main supercell updraft and along the trailing out ow boundary, leading to the formation of occasionally intense misovortices. HCRs perpendicular to storm motion are found to have a detrimental effect on the strength and persistence of the lowlevel mesocyclone, particularly during its initial development. Though the mean environment is less supportive of low-level rotation with a wind profile conducive to HCRs oriented parallel to storm motion, such HCRs are found to often enhance the low-level mesocyclone circulation. When anvil shading is included, stabilization results in generally weaker low-level mesocyclone circulation, regardless of HCR orientation. Moreover, HCRs diminish in the near-storm environment such that the effects of HCRs on the supercell are mitigated. HCRs are also shown to be a necessary condition for the formation of so-called "feeder clouds" and anking line convection in these simulations. These findings suggest potentially important rami fications regarding both non-mesocyclone and mesocyclone tornadoes in supercell thunderstorms in an environment with active boundary layer convection.

Nowotarski, Christopher J.

42

What can simulated convective storms tell us about thunderstorm behavior under climate change?  

NASA Astrophysics Data System (ADS)

Isolated convective storms are responsible for numerous high-impact weather events. Their frequency and intensity under the present climate change has been the subject of much speculation, and this uncertainty is magnified when considering that these storms are sensitive to modest changes in their ambient environments. In this work we use an idealized, cloud-resolving model to study the role of environmental changes on storm behavior. This approach is useful since it allows direct comparison of storm morphology between one environment (e.g., the present) and another (e.g., the future). Our current understanding is that for much of the globe, atmospheric temperature and water vapor will increase, and, at least in the middle latitudes, tropospheric wind shear may decrease owing to a weakening of the zonal temperature gradient that maintains the polar jet stream. The vertically integrated effects of temperature and water vapor can be summarized by the convective available potential energy (CAPE), a measure of buoyant energy available to updrafts. These two parameters, CAPE and tropospheric wind shear, are known to exert significant control on storm behavior and are explored herein. Between simulations, either CAPE or shear or both are varied (by 200 J kg-1 and 2 m s-1, respectively), and storm properties in the various environments are then compared. In 112 experiment pairs with CAPE increased and shear decreased, 56% of storms produce stronger updrafts, with some that are stronger by as much as 20 m s-1. However, the magnitude and sign of the change is strongly dependent on the starting values of CAPE and shear. For example, in simulations where CAPE is already >2000 J kg-1 and shear is weak, such as the moist tropics, small changes to either parameter actually work to reduce updraft intensity, by 5 to 10 m/s. In environments where CAPE is very low (400 J kg-1), addition of just 200 J kg-1 of buoyancy can be the difference between storms that last 30-40 minutes, and storms that last over 2 hours and produce updrafts in excess of 30 m s-1. When considering storm rotation, only 44% of storms produce more vorticity near the ground when CAPE is increased and shear decreased. As with updraft speeds, these results are also highly sensitive to starting values. Additional analyses will be presented, including impacts on total rainfall, surface wind speeds, and hail production. These results underscore the need for further study of convective storm predictability as climate continues to change and highlight the importance of climate change as a regional phenomenon with implications that go beyond global temperatures. It is hoped that this work will foster discussion on such regional trends, what their outcomes might be, and the vital role of convective storms in earth's climate system.

Kirkpatrick, C.

2013-12-01

43

C/NOFS and radar observations during a convective ionospheric storm event over South America  

NASA Astrophysics Data System (ADS)

The development of a convective ionospheric storm is studied using three radars, the C/NOFS satellite, airglow instrumentation, and a numerical model. First detected in the form of convective plumes over the Eastern Pacific, plasma irregularities, airglow signatures, plumes, and irregularities were also detected over Brazil and then Peru. Dynamo conditions were such that a modest prereversal enhancement was recorded at both Christmas Island and Peru and probably over Brazil as well. No prereversal enhancement occurred during the next two days and no plumes were detected. The numerical model reproduced the results quite well over Peru. Evidence for seeding by both gravity waves and the Kelvin-Helmholtz instability is presented.

Kelley, M. C.; Rodrigues, F. S.; Makela, J. J.; Tsunoda, R.; Roddy, P. A.; Hunton, D. E.; Retterer, J. M.; de La Beaujardiere, O.; de Paula, E. R.; Ilma, R. R.

2009-08-01

44

Sensitivity of the Amazon rainforest to convective storms  

NASA Astrophysics Data System (ADS)

The Amazon rainforest is the largest contiguous continental tropical forest in the world and is a world center of carbon storage, biodiversity, biogeochemical cycles and biogeophysical processes that affect the Earth climate system. Yet anthropogenic activities have produced changes in the forest-climate system. Consequently, an increase in rainfall in both the Western and Central Amazon and a decrease in the Eastern Amazon are expected due to these anthropogenic activities. While the projected decrease in rainfall has been discussed under the context of drought, deforestation, and fires, the effect of an increase in rainfall, and associated convective processes, on forest ecosystems has been overlooked. Across the Amazon rainforest, Western Amazonia has the highest precipitation rates, wood productivity, soil fertility, recruitment and mortality rates. Yet our field-measured tree mortality data from blowdowns that occurred in Western and Central Amazonia do not show a statistical difference in tree mortality between these regions. However, downburst velocities associated with these disturbances were calculated to be lower in Western Amazonia than in the Central Amazon. This suggests the Western Amazon is more highly sensitive to intense convective systems. This result is particularly relevant given the expected increase in rainfall in the Western and Central Amazon. The increase in rainfall is associated with more intense convective systems that in turn imply an increase in low level jet stream (LLJ) intensity east of the Andes. The presence of the LLJ is the main cause of squall lines and an increase in LLJ intensity will therefore cause increased propagation of squall lines into the Amazon basin. More frequent and active squall lines have the potential to increase the intensity and frequency of downbursts responsible for large forest blowdowns that will affect the biogeophysical feedbacks on the forest ecosystem and carbon budget.

Negron Juarez, R. I.; Chambers, J. Q.; Rifai, S. W.; Urquiza Munoz, J. D.; Tello, R.; Alegria Munoz, W.; Marra, D.; Ribeiro, G.; Higuchi, N.

2012-12-01

45

GOES 12 observations of convective storm variability and evolution during the Tropical Composition, Clouds and Climate Coupling Experiment field program  

NASA Astrophysics Data System (ADS)

This study characterizes convective clouds that occurred during the Tropical Composition, Clouds and Climate Coupling Experiment as observed within GOES imagery. Overshooting deep convective cloud tops (OT) that penetrate through the tropical tropopause layer and into the stratosphere are of particular interest in this study. The results show that there were clear differences in the areal coverage of anvil cloud, deep convection, and OT activity over land and water and also throughout the diurnal cycle. The offshore waters of Panama, northwest Colombia, and El Salvador were the most active regions for OT-producing convection. A cloud object tracking system is used to monitor the duration and areal coverage of convective cloud complexes as well as the time evolution of their cloud-top microphysical properties. The mean lifetime for these complexes is 5 hours, with some existing for longer than 16 hours. Deep convection is found within the anvil cloud during 60% of the storm lifetime and covered 24% of the anvil cloud. The cloud-top height and optical depth at the storm core followed a reasonable pattern, with maximum values occurring 20% into the storm lifetime. The values in the surrounding anvil cloud peaked at a relative age of 20%-50% before decreasing as the convective cloud complex decayed. Ice particle diameter decreased with distance from the core but generally increased with storm age. These results, which characterize the average convective system during the experiment, should be valuable for formulating and validating convective cloud process models.

Bedka, Kristopher M.; Minnis, Patrick

2010-05-01

46

A Five-Year Climatology of Elevated Severe Convective Storms in the United States East of the Rocky Mountains  

Microsoft Academic Search

A 5-yr climatology of elevated severe convective storms was constructed for 1983-87 east of the Rocky Mountains. Potential cases were selected by finding severe storm reports on the cold side of sur- face fronts. Of the 1826 days during the 5-yr period, 1689 (91%) had surface fronts east of the Rockies. Of the 1689 days with surface fronts, 129 (8%)

Katherine L. Horgan; David M. Schultz; JOHN E. HALES JR; Stephen F. Corfidi; Robert H. Johns

2007-01-01

47

Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm  

NASA Astrophysics Data System (ADS)

Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme within a meso-? scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration is given to the model’s dynamical response to the forcing as well as to the sensitivity of the LHN scheme to uncertainty in the observations and the environment. The results indicate that the LHN scheme is well able to capture the dynamical structure and the right rainfall amount of the storm in a perfect environment. This holds true even in degraded environments but a number of important issues arise. In particular, changes in the low-level humidity field are found to affect mainly the precipitation amplitude during the assimilation with a fast adaptation of the storm to the system dynamics determined by the environment during the free forecast. A constant bias in the environmental wind field, on the other hand, has the potential to render a successful assimilation with the LHN scheme difficult, as the velocity of the forcing is not consistent with the system propagation speed determined by the wind. If the rainfall forcing moves too fast, the system propagation is supported and the assimilated storm and forecasts initialised therefrom develop properly. A too slow forcing, on the other hand, can decelerate the system and eventually disturb the system dynamics by decoupling the low-level moisture inflow from the main updrafts during the assimilation. This distortion is sustained in the free forecast. It has further been found that a sufficient temporal resolution of the rainfall input is crucial for the successful assimilation of a fast moving, coherent convective storm and that the LHN scheme, when applied to a convective storm, appears to necessitate a careful tuning.

Leuenberger, D.; Rossa, A.

2007-12-01

48

Numerical simulation of a mesoscale convective system and a tornadic supercell storm in Marmara Region, Turkey  

NASA Astrophysics Data System (ADS)

Although there are not studies done in region, convective storms cause severe weather and significant damage in Turkey. In this study, a severe convection case of 15 August 2004 is simulated which occurred in the Marmara region, the most populated and industrialized region of Turkey. The convection was triggered by a mesoscale convective system (MCS) and a small tornadic supercell caused by pre-frontal instability. Despite the fact that the MCS had been indicated by forecast models and early warnings had been issued for Istanbul ahead of time, the supercellular convection which was responsible for the tornado in Yalova could not be predicted. The tornado caused no injuries, but there was substantial damage in fields and some buildings. In this study, Advanced Research WRF (WRF-ARW) is used for a fine-resolution simulation of the phenomena, initializated with GFS analysis data. Results are very encouraging, with the succesful capture of the mesoscale convective system and the small supercell. The mesocyclone and rotation of the cell is clear, and precipitation estimates are satisfying.

Kahraman, A.; Kadioglu, M.

2009-04-01

49

Initialization of a modeled convective storm using Doppler radar-derived fields  

SciTech Connect

A method is developed to initialize convective storm simulations with Doppler radar-derived fields. Input fields for initialization include velocity, rain water derived from radar reflectivity, and pressure and temperature fields obtained through thermodynamic retrieval. A procedure has been developed to fill in missing wind data, followed by a variational adjustment to the filled wind field to minimize [open quotes]shocks[close quotes] that would otherwise cause the simulated fields to deteriorate rapidly. A series of experiments using data from a simulated storm establishes the feasibility of the initialization method. Multiple Doppler radar observations from the 20 May 1977 Del City tornadic storm are used for the initialization experiments. Simulation results initialized from observations taken at two different stages of storm development are shown and compared to observations taken at later times. A simulation initialized from one of the observation times showed good agreement with subsequent observations, though the simulated storm appeared to be evolving much faster than observed. Possible mechanisms for error growth are discussed.

Lin, Y.

1992-01-01

50

CONVECTIVE BURSTS AND THE COUPLING OF SATURN'S EQUATORIAL STORMS AND INTERIOR ROTATION  

SciTech Connect

Temporal variations of Saturn's equatorial jet and magnetic field hint at rich dynamics coupling the atmosphere and the deep interior. However, it has been assumed that rotation of the interior dynamo must be steady over tens of years of modern observations. Here we use a numerical convection model and scaling estimates to show how equatorial convective bursts can transfer angular momentum to the deeper interior. The numerical model allows angular momentum transfer between a fluid outer spherical shell and a rigid inner sphere. Convection drives a prograde equatorial jet exhibiting quasiperiodic bursts that fill the equatorial volume outside the tangent cylinder. For each burst strong changes in the equatorial surface velocity are associated with retrograde torque on the inner sphere. Our results suggest that Saturn's Great White Spot, a giant storm that was observed to fill the equatorial region in 1990, could mobilize a volume of fluid carrying roughly 15% of Saturn's moment of inertia. Conservation of angular momentum then implies that a 20% change in the equatorial jet angular velocity could change the average interior rotation rate by about 0.1%-roughly an order of magnitude less than the apparent rotation rate changes associated with Saturn's kilometric radio (SKR) signal. However, if the SKR signal originates outside the liquid metal core in a 'planetary tachocline' that separates the layer of fast zonal flow from the magnetically controlled and slowly convecting deep interior, then convective bursts can provide a possible mechanism for the observed {approx}1% SKR changes.

Heimpel, Moritz [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Aurnou, Jonathan M., E-mail: mheimpel@ualberta.ca, E-mail: aurnou@ucla.edu [Department of Earth and Space Sciences, University of California, Los Angeles, CA (United States)

2012-02-10

51

Influence of the Convection Electric Field Models on Predicted Plasmapause Positions During Magnetic Storms  

NASA Technical Reports Server (NTRS)

In the present work, we determine how three well documented models of the magnetospheric electric field, and two different mechanisms proposed for the formation of the plasmapause influence the radial distance, the shape and the evolution of the plasmapause during the geomagnetic storms of 28 October 2001 and of 17 April 2002. The convection electric field models considered are: Mcllwain's E51) electric field model, Volland-Stern's model and Weimer's statistical model compiled from low-Earth orbit satellite data. The mechanisms for the formation of the plasmapause to be tested are: (i) the MHD theory where the plasmapause should correspond to the last-closed- equipotential (LCE) or last-closed-streamline (LCS), if the E-field distribution is stationary or time-dependent respectively; (ii) the interchange mechanism where the plasmapause corresponds to streamlines tangent to a Zero-Parallel-Force surface where the field-aligned plasma distribution becomes convectively unstable during enhancements of the E-field intensity in the nightside local time sector. The results of the different time dependent simulations are compared with concomitant EUV observations when available. The plasmatails or plumes observed after both selected geomagnetic storms are predicted in all simulations and for all E-field models. However, their shapes are quite different depending on the E-field models and the mechanisms that are used. Despite the partial success of the simulations to reproduce plumes during magnetic storms and substorms, there remains a long way to go before the detailed structures observed in the EUV observations during periods of geomagnetic activity can be accounted for very precisely by the existing E-field models. Furthermore, it cannot be excluded that the mechanisms currently identified to explain the formation of "Carpenter's knee" during substorm events, will', have to be revised or complemented in the cases of geomagnetic storms.

Pierrard, V.; Khazanov, G.; Cabrera, J.; Lemaire, J.

2007-01-01

52

An estimation of the condensation rates in three severe storm systems from satellite observations of the convective mass flux  

NASA Technical Reports Server (NTRS)

A technique was developed for estimating the condensation rates of convective storms using satellite measurements of cirrus anvil expansion rates and radiosonde measurements of environmental water vapor. Three cases of severe convection in Oklahoma were studied and a diagnostic model was developed for integrating radiosonde data with satellite data. Two methods were used to measure the anvil expansion rates - the expansion of isotherm contours on infrared images, and the divergent motions of small brightness anomalies tracked on the visible images. The differences between the two methods were large as the storms developed, but these differences became small in the latter stage of all three storms. A comparison between the three storms indicated that the available moisture in the lowest levels greatly affected the rain rates of the storms. This was evident from both the measured rain rates of the storms and the condensation rates estimated by the model. The possibility of using this diagnostic model for estimating the intensities of convective storms also is discussed.

Mack, R. A.; Wylie, D. P.

1982-01-01

53

Occurrence of summer and winter storms in GPS TEC during solar minimum period  

Microsoft Academic Search

The GPS measurements collected by IGS\\/EPN over Europe were used to study of the ionosphere response to summer (July 2009) and winter (October 2008) storms. Analysis was based on behaviour of GPS TEC variations over individual GPS stations within 35-70N latitudes and GPS TEC maps created with high resolution. The features of spatial and temporal dynamics of the ionosphere during

Irk Shagimuratov; Andrzej Krankowski; Irina Zakharenkova; Nadezhda Tepenitsyna; Galina Yakimova

2010-01-01

54

Convective Activities in the Tropical Western Pacific and Their Impact on the Northern Hemisphere Summer Circulation  

Microsoft Academic Search

Interannual and intraseasonal variations of convective activities in the tropical western Pacific during summer and their impact on the Northern Hemisphere circulation are investigated by using satellite cloud amount, sea surface temperature (SST) and geopotential data for 7 years (1978-1984). During summers when SST in the tropical western Pacific is about 1.0°C warmer than normal, active convection regions consisting of

Tsuyoshi Nitta

1987-01-01

55

The distribution of deep convection over ocean and land during the Asian summer monsoon  

NASA Technical Reports Server (NTRS)

The characteristics of the convection over the summer monsoon are investigated using the highly reflective cloud (HRC) data set (which is a subjective-analyzed daily index of organized deep convection, at one degree resolution, for years between 1971 and 1988 of the polar-orbiting satellite imagery). The results of the analysis are used to obtain the geographical distribution of HRCs for the climatological mean summer monsoon season and its four component months and to examine the intraseasonal variation of convection over selected areas. The model results of Webster and Chou (1980) are tested by comparing the relative frequency of occurrence of HRC for continental areas, coastal zones, and open ocean.

Grossman, Robert L.; Garcia, Oswaldo

1990-01-01

56

Evaluation and development of satellite inferences of convective storm intensity using combined case study and thunderstorm model simulations  

NASA Technical Reports Server (NTRS)

Observational requirements for predicting convective storm development and intensity as suggested by recent numerical experiments are examined. Recent 3D numerical experiments are interpreted with regard to the relationship between overshooting tops and surface wind gusts. The development of software for emulating satellite inferred cloud properties using 3D cloud model predicted data and the simulation of Heymsfield (1981) Northern Illinois storm are described as well as the development of a conceptual/semi-quantitative model of eastward propagating, mesoscale convective complexes forming to the lee of the Rocky Mountains.

Cotton, W. R.; Tripoli, G. J.

1982-01-01

57

Microwave-lightning cooperation to provide frequent rainfall scenarios of Mediterranean convective storms  

NASA Astrophysics Data System (ADS)

The close connection between lightning occurrences and convection is the foundation of the employment of ground based lightning location networks data as proxies of storms position and evolution. Weak statistics support their direct use for quantitative precipitation estimation, while the usefulness of information related with the position and frequency of lightning strokes arises forcefully by the visual inspection of maps. On the contrary, microwave-based precipitation retrieval techniques, recognized as a good tool to quantify the instantaneous rainfall amount, suffer from low spatial and most low temporal resolution related to the orbital characteristics of the low earth observation (LEO) satellites accommodating MW sensors. A cooperative microwave-lightning system is developed that exploits lightning network data to propagate rain fields estimated using multifrequency brightness temperatures acquired by AMSU passive radiometers. The method both drives the movement of the rain cells using lightning occurencies as well as modifies the morphology and the intensity of the storm according to the course of spatial and temporal distribution of lightning strokes. The successful application of this method to the analysis of some severe storms included in FP6 project FLASH (Observations, Analysis and Modeling of Lightning Activity in Thunderstorms for use in Short Term Forecasting of Flash Floods) will be illustrated.

Dietrich, S.; di Paola, F.; Mugnai, A.

2009-09-01

58

Sprite-producing Convective Storms within the Colorado Lightning Mapping Array  

NASA Astrophysics Data System (ADS)

The multi-year, multi-institution effort entitled Physical Origins of Coupling to the Upper Atmosphere from Lightning (PhOCAL), has among its goals to qualitatively understand the meteorology and lightning flash characteristics that produce the unusual and/or very energetic lightning responsible for phenomena such as sprites, halos, elves, blue jets and gigantic jets, collectively known as Transient Luminous Events (TLEs). A key task is to obtain simultaneous video, ideally with a high-speed imager (HSI), of both a TLE and its parent lightning discharge, within the domain of a 3-D Lightning Mapping Array (LMA). While conceptually simple, this task is logistically quite complicated. In 2012, a new 15-station Colorado LMA (COLMA) became operational, covering northeastern Colorado, with the Yucca Ridge Field Station (YRFS) near its western edge. The National Charge Moment Change Network (CMCN), which since 2007 has been documenting sprite-class +CGs (those with impulse change moment changes >100 C km), indicates that a strong gradient of energetic +CGs exists west-to-east through the COLMA, with the most likely region for sprite-producing storms being in the COLMA eastern fringes (western Kansas and Nebraska). Yet, on 8 and 25 June, 2012, intense convective systems formed in the COLMA along and just east of the Front Range, producing severe weather and intense lightning. On the 8th, four sprite parent +CGs were captured at 3000 fps from YRFS with the sprites confirmed by dual (conventional speed) cameras in New Mexico. In a second storm on the 25th, viewing conditions prevented +CG video acquisition, but sprites were logged over the COLMA and detailed reconstructions of the discharges are being made. The parent discharges often began as upward negative leaders propagating into a mid-level positive charge layer at 8-10 km. They often originated within or near the convective core before expanding outward into a stratiform region and involving several hundred square kilometers, to be followed by +CG and strong continuing currents. LMA indications of recoil leaders appear confirmed by some high-speed video. These storms were somewhat smaller than the typical sprite-bearing MCS. The storm structures will be categorized using GOES IR, NEXRAD reflectivity, NLDN lightning data, CMCN impulse charge moment data, and full charge moment charge retrievals. The sprite parent CG discharges will be cataloged along with their points of origin, the height and volume from which charge is removed, the charge lowered to ground, and the continuing current characteristics. These CGs will be placed in the context of the storms' meteorological structure and evolution.

Lyons, W. A.; Cummer, S. A.; Rison, W.; Krehbiel, P. R.; Lang, T. J.; Rutledge, S. A.; Lu, G.; Stanley, M. A.; Ashcraft, T.; Nelson, T. E.

2012-12-01

59

The Impact of Microphysics and Planetary Boundary Layer Physics on Model Simulation of U.S. Deep South Summer Convection  

NASA Technical Reports Server (NTRS)

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics pararneterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRn Center to select NOAAlNWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boWldary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage oflightuing activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

McCaul, Eugene W., Jr.; Case, Jonathan L.; Zavodsky, Bradley T.; Srikishen, Jayanthi; Medlin, Jeffrey M.; Wood, Lance

2014-01-01

60

The Impacts of Microphysics and Planetary Boundary Layer Physics on Model Simulations of U. S. Deep South Summer Convection  

NASA Technical Reports Server (NTRS)

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics parameterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRT Center to select NOAA/NWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boundary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage of lightning activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

McCaul, E. W., Jr.; Case, J. L.; Zavodsky, B. T.; Srikishen, J.; Medlin, J. M.; Wood, L.

2014-01-01

61

Midweek Increase in U.S. Summer Rain and Storm Heights, Suggests Air Pollution Invigorates Rainstorms  

NASA Technical Reports Server (NTRS)

Tropical Rainfall Measuring Mission (TRMM) satellite data show a significant midweek increase in summertime rainfall over the southeast U.S., due to afternoon intensification. TRMM radar data show a significant midweek increase in rain area and in the heights reached by afternoon storms. Weekly variations in model-reanalysis wind patterns over the region and in rain-gauge data are consistent with the satellite data. A midweek decrease of rainfall over the nearby Atlantic is also seen. EPA measurements of particulate concentrations show a midweek peak over much of the U.S. These observations are consistent with the theory that anthropogenic air pollution suppresses cloud-drop coalescence and early rainout during the growth of thunderstorms over land, allowing more water to be carried above the 0 C isotherm, where freezing yields additional latent heat, invigorating the storms--most dramatically evidenced by the shift in the midweek distribution of afternoon-storm heights--and producing large ice hydrometeors. The enhanced convection induces regional convergence, uplifting and an overall increase of rainfall. Compensating downward air motion suppresses convection over the adjacent ocean areas. Pre-TRMM-era data suggest that the weekly cycle only became strong enough to be detectable beginning in the 1980's. Rain-gauge data also suggest that a weekly cycle may have been detectable in the 1940's, but with peak rainfall on Sunday or Monday, possibly explained by the difference in composition of aerosol pollution at that time. This "weekend effect" may thus offer climate researchers an opportunity to study the regional climate-scale impact of aerosols on storm development and monsoon-like circulation.

Bell, Thomas L.; Rosenfeld, Daniel; Kim, Kyu-Myong; Yoo, Jung-Moon; Hahnenberger, Maura

2007-01-01

62

Diurnal evolution and distribution of warm-season convective storms in different prevailing wind regimes over contiguous North China  

NASA Astrophysics Data System (ADS)

The diurnal evolution and distribution of warm-season convective storms in different prevailing wind regimes at the 925 hPa and 500 hPa levels over contiguous North China have been studied using a climatology based on radar reflectivity mosaics, soundings, and reanalysis data from 15 May to 15 September, in 2008-2011. In the wind regimes at the 925 hPa level, the frequency of occurrence of convection is highest for south-southwesterly flows, followed by that for south-southeasterly flows. The low-level southerly warm and moist flow over the foothills and plains favors initiation and intensification of convection resulting from topographic forcing. Among the wind regimes at the 500 hPa level, the frequency of occurrence of convection shows a pronounced maximum for west-southwesterly flows, and most of these storms initiate and develop over the foothills and plains. Convection in the wind regime shows the morphology and slowly east-southeastward moving characteristics of well-organized, longer-lived systems, with environmental conditions conducive to vertical wind shear and instability. At the 500 hPa level, the high frequency of occurrence of convection for west-southwesterly flows is followed by that for west-northwesterly flows. Under west-northwesterly flows, convective storms initiated over mountains located to the northwest in the early afternoon move rapidly to the plains in the southeast of the study region. These storms show the primary formation characteristics of shorter-lived convection and intensify noticeably as they move from the mountains to the foothills and plains.

Chen, Mingxuan; Wang, Yingchun; Gao, Feng; Xiao, Xian

2014-03-01

63

Assessment of the European Severe Convective Storm Climatology using Reanalysis Data  

NASA Astrophysics Data System (ADS)

Thunderstorms and their accompanying phenomena like large hail, severe wind gusts, tornadoes and excessive precipitation are increasingly recognized as an important hazard to life and property in Europe. Within the project STEPCLIM ("Severe Thunderstorm Evaluation and Predictability in Climate Models"), we link historic severe thunderstorm events in Europe to atmospheric conditions resolved by reanalysis data. The aim is to find a relation between quantities, which can be represented by relatively coarse climate models, and the occurrence of short-lived and local severe weather phenomena associated with convection. At a later stage, this relation will be applied to climate forecast data, so that the effects of climate change on the frequency and intensity of severe convective storms can be investigated. A set of parameters is defined for the characterization of the local state of the atmosphere at any given point in place and time. These parameters represent the "ingredients" for severe thunderstorms, namely instability, vertical wind shear, and a measure of support for convective initiation. They are calculated from 6-hourly ERA-Interim reanalysis fields (1979-2011). The such derived fields are compared with the occurrence or non-occurrence of severe weather phenomena according to the quality-controlled severe storm reports collected in the European Severe Weather Database (ESWD). A logistic regression is then fitted in order to find the best relation between a given combination of parameters and the associated severe weather probability. This relation is postulated to be invariant against any changes in climate, an assumption that is justified by the physics-based nature of the chosen parameters. With this restriction, the derived relation can be used to estimate future severe weather frequencies based on modeled climatic changes of the underlying parameter distributions. In this presentation, emphasis is put on the used methodology and on a way to deal with spatial and temporal inhomogeneities of the observational data.

Pistotnik, Georg; Groenemeijer, Pieter; Kühne, Thilo

2013-04-01

64

Simulation and Analysis of Infrasound Generated by Convective Storms and Tornadoes  

NASA Astrophysics Data System (ADS)

Observational studies have shown that severe storms can emit abnormally strong, sustained infrasound in the 0.5-5 Hz frequency range. There is reason to believe that the infrasonic emissions come from developing and mature tornadoes, but some ambiguity remains in the interpretation of the data. It is fair to say that we do not yet fully understand the conditions for which a vortex signal is discernible from the infrasound of non-tornadic sources within a storm. There is a pressing need to advance our fundamental understanding of the different mechanisms that generate infrasound in atmospheric convection. To this end, numerical modeling may be the best method of investigation. We are exploring this avenue of research with a customized version of the Regional Atmospheric Modeling System (c-RAMS). Previous studies have established the basic credibility of c-RAMS for simulating acoustic phenomena. More recently, we have developed a convenient method for diagnosing the primary sources of infrasound in complex storm simulations. The method is based on a generalization of Lighthill's acoustic analogy, and is aptly illustrated in the context of a simulated cumulonimbus. Applying the diagnostic method to this system, we find that the 0.1-1 Hz infrasound of diabatic processes in the hail-to-rain transition layer dominates that of turbulent wind fluctuations covering the entire storm. We have also used c-RAMS to investigate the infrasound of tornadoes created by artificial buoyancy forcing in a dry, rotational environment. The simulated tornadoes have realistic structure, but their cores are typically quiet in the frequency range of interest. In other words, we find that dry fluctuations of the vortex core may not provide a robust source of discernible infrasound. Apparent deficiencies of earlier theories that predicted otherwise will be addressed. This work was supported by NSF grant AGS-0832320.

Schecter, D.; Nicholls, M.

2011-12-01

65

Columns of differential reflectivity: a precursor for storm evolution and convective rain  

NASA Astrophysics Data System (ADS)

Nowcasting aims at providing accurate information about weather hazards related to convection at a very high refresh rate well suited for fast evolving convective systems. Polarimetric weather radars arise as a key tool to provide "seamless" analysis and nowcast of convective risk to aviation, because of their ability to observe 3dimensional storm structure, evolution, microphysical processes, and generated precipitation. Columns of differential reflectivity ZDR measured by polarimetric weather radars are prominent signatures associated with thunderstorm updrafts. Since greater vertical velocities can loft larger drops and water-coated ice particles to higher altitudes above the environmental freezing level, the integrated ZDR column above the freezing level increases with increasing updraft intensity. Frequently, they can extend several kilometers above the environmental freezing level. These positive ZDR values above the environmental freezing level point to the presence of large, oblate raindrops and perhaps water-coated hailstones and graupel. Analyses on the informative content of ZDR columns as precursor for storm evolution will be presented based on both the X-band polarimetric data collected by the twin radars (XPol Bonn and XPol Jülich) in the Bonn area, Germany, and volume radar data collected with the S-band KOUN radar, in Norman, Oklahoma. In order to derive the ZDR column product, radar volume data is interpolated onto a three-dimensional Cartesian (x,y,z) grid and then, for each (x,y) coordinate, the number of vertical grid boxes above the freezing level containing ZDR values in excess of a predetermined threshold (=1dB) are counted. The ZDR column product is simply a count of the number of grid boxes, which can be converted into "ZDR column volume" by simply multiplying the count by the dimension ?x?y?z of the grid box. Interdependencies between the volumes of ZDR columns above the environmental freezing level, precipitation near the surface, the VIL-value (Vertically Integrated Liquid) and the cloud top heights already in use for monitoring the tendency of convective development in aviation applications are analyzed. The VIL-value at a certain location is the sum of all observed radar reflectivities converted to liquid water content in a vertical column above this location and can be regarded as a measure for the potential rainfall. Time series of all variables are then compared with each other both qualitatively and quantitatively. Analyses show among others that the ZDR column volume above the 0°C level is related to a time-lagged increase in low-level horizontal reflectivity ZH. This implies that the increasing ZDR column volume precedes an intensification of surface precipitation and can be identified as a precursor for convective rain.

Troemel, S.; Diederich, M.; Kumjian, M. R.; Picca, J. C.; Simmer, C.

2012-12-01

66

Severe convection and lightning in subtropical South America  

NASA Astrophysics Data System (ADS)

Satellite radar and radiometer data show that subtropical South America has the world's deepest convective storms, robust mesoscale convective systems, and very frequent large hail. We determine severe weather characteristics for the most intense precipitation features seen by satellite in this region. In summer, hail and lightning concentrate over the foothills of western Argentina. Lightning has a nocturnal maximum associated with storms having deep and mesoscale convective echoes. In spring, lightning is maximum to the east in association with storms having mesoscale structure. A tornado alley is over the Pampas, in central Argentina, distant from the maximum hail occurrence, in association with extreme storms. In summer, flash floods occur over the Andes foothills associated with storms having deep convective cores. In spring, slow-rise floods occur over the plains with storms of mesoscale dimension. This characterization of high-impact weather in South America provides crucial information for socioeconomic implications and public safety.

Rasmussen, Kristen L.; Zuluaga, Manuel D.; Houze, Robert A.

2014-10-01

67

Diagnosis of the secondary circulation of tropical storm Bilis (2006) and the effects of convective systems on its track  

NASA Astrophysics Data System (ADS)

We diagnose characteristics of the quasi-balanced flow and secondary circulation (SC) of tropical storm Bilis (2006) using the potential vorticity (PV)- ? inversion method. We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall. The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV- ? inversion. The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75% of the magnitude simulated using the Weather Research and Forecasting (WRF) model. The SC of Bilis (2006) contained two strong regions of ascending motion, both of which were located in the southwest quadrant of the storm. The first (150-200 km southwest of the storm center) corresponded to the eyewall region, while the second (approximately 400 km southwest of the storm center) corresponded to latent heat release associated with strong precipitation in major spiral rainbands. The SC was very weak in the northeast quadrant (the upshear direction). Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear (by 20%-25%). This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant, with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels. The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about -2.14 and -0.7 m s-1, respectively. These steering flows contributed substantially to the zonal (66.15%) and meridional (33.98%) motion of the storm at 0000 UTC 15 July 2006. The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward. The direction of the large-scale meridional steering flow (3.02 m s-1) was opposite to the actual meridional motion (-2.06 m s-1).

Yu, Jinhua; Fu, Hao; Tang, Sheng; Sheng, Siwei

2014-02-01

68

Evaluation and development of satellite inferences of convective storm intensity using combined case study analysis and thunderstorm model simulations  

NASA Technical Reports Server (NTRS)

Major research accomplishments which were achieved during the first year of the grant are summarized. The research concentrated in the following areas: (1) an examination of observational requirements for predicting convective storm development and intensity as suggested by recent numerical experiments; (2) interpretation of recent 3D numerical experiments with regard to the relationship between overshooting tops and surface wind gusts; (3) the development of software for emulating satellite-inferred cloud properties using 3D cloud model predicted data; and (4) the development of a conceptual/semi-quantitative model of eastward propagating, mesoscale convective complexes forming to the lee of the Rocky Mountains.

Cotton, W. R.; Tripoli, G. J.

1980-01-01

69

P2.17 Impact of Spatial Over-sampling by Phase-Array Radar on Convective-Storm Analysis using Ensemble Kalman Filter and Simulated Data  

E-print Network

P2.17 Impact of Spatial Over-sampling by Phase-Array Radar on Convective-Storm Analysis using and Computer Engineering University of Oklahoma 1. Introduction 1 The phased-array radar (PAR) of the National

Xue, Ming

70

Automatic differentiation as a tool for sensitivity analysis of a convective storm in a 3-D cloud model  

SciTech Connect

The ADIFOR automatic differentiation tool is applied to a 3-D storm-scale meteorological model to generate a sensitivity-enhanced code capable of providing derivatives of all model output variables and related diagnostic (derived) parameters as a function of specified control parameters. The tangent linear approximation, applied to a deep convective storm by the first of its kind using a full-physics compressible model, is valid up to 50 min for a 1% water vapor perturbations. The result is very encouraging considering the highly nonlinear and discontinuous properties of solutions. The ADIFOR-generated code has provided valuable sensitivity information on storm dynamics. Especially, it is very efficient and useful for investigating how a perturbation inserted at earlier time propagates through the model variables at later times. However, it is computationally very expensive to be applied to the variational data assimilation, especially for 3-D meteorological models, which potentially have a large number of input variables.

Park, S.K.; Droegemeier, K.K. [Univ. of Oklahoma, Norman, OK (United States); Bischof, C.H. [Argonne National Lab., IL (United States). Mathematics and Computer Science Div.

1996-10-01

71

Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes  

NASA Astrophysics Data System (ADS)

Globally, changes in stable isotope ratios of oxygen and hydrogen (? 18O and ? D ) in the meteoric water cycle result from distillation and evaporation processes. Isotope fractionation occurs when air masses rise in elevation, cool, and reduce their water-vapor holding capacity with decreasing temperature. As such, ? 18O and ? D values from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges. Based on 234 stream-water samples, we demonstrate that areas experiencing deep convective storms in the eastern south-central Andes (22-28° S) do not show the commonly observed relationship between ? 18O and ? D with elevation. These convective storms arise from intermontane basins, where diurnal heating forces warm air masses upward, resulting in cloudbursts and raindrop evaporation. Especially at the boundary between the tropical and extra-tropical atmospheric circulation regimes where deep-convective storms are very common (?26° to 32° N and S), the impact of such storms may yield non-systematic stable isotope-elevation relationships as convection dominates over adiabatic lifting of air masses. Because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation, linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions, and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells.

Rohrmann, Alexander; Strecker, Manfred R.; Bookhagen, Bodo; Mulch, Andreas; Sachse, Dirk; Pingel, Heiko; Alonso, Ricardo N.; Schildgen, Taylor F.; Montero, Carolina

2014-12-01

72

Enhancement of seasonal prediction of East Asian summer rainfall related to western tropical Pacific convection  

NASA Astrophysics Data System (ADS)

The prediction skills of climate model simulations in the western tropical Pacific (WTP) and East Asian region are assessed using the retrospective forecasts of seven state-of-the-art coupled models and their multi-model ensemble (MME) for boreal summers (June-August) during the period 1983-2005, along with corresponding observed and reanalyzed data. The prediction of summer rainfall anomalies in East Asia is difficult, while the WTP has a strong correlation between model prediction and observation. We focus on developing a new approach to further enhance the seasonal prediction skill for summer rainfall in East Asia and investigate the influence of convective activity in the WTP on East Asian summer rainfall. By analyzing the characteristics of the WTP convection, two distinct patterns associated with El Niño-Southern Oscillation developing and decaying modes are identified. Based on the multiple linear regression method, the East Asia Rainfall Index (EARI) is developed by using the interannual variability of the normalized Maritime continent-WTP Indices (MPIs), as potentially useful predictors for rainfall prediction over East Asia, obtained from the above two main patterns. For East Asian summer rainfall, the EARI has superior performance to the East Asia summer monsoon index or each MPI. Therefore, the regressed rainfall from EARI also shows a strong relationship with the observed East Asian summer rainfall pattern. In addition, we evaluate the prediction skill of the East Asia reconstructed rainfall obtained by hybrid dynamical-statistical approach using the cross-validated EARI from the individual models and their MME. The results show that the rainfalls reconstructed from simulations capture the general features of observed precipitation in East Asia quite well. This study convincingly demonstrates that rainfall prediction skill is considerably improved by using a hybrid dynamical-statistical approach compared to the dynamical forecast alone.

Lee, Doo Young; Ahn, Joong-Bae; Yoo, Jin-Ho

2014-09-01

73

Effects of vertical wind shear on convective development during a landfall of severe tropical storm Bilis (2006)  

NASA Astrophysics Data System (ADS)

Effects of vertical wind shear on convective development during the landfall of tropical storm Bilis (2006) are investigated with a pair of sensitivity experiments using a two-dimensional cloud-resolving model. The validated simulation data from Wang et al. [Wang, D., Li, X., Tao, W.-K., Liu, Y., Zhou, H., 2009: Torrential rainfall processes associated with a landfall of severe tropical storm Bilis (2006): A two-dimensional cloud-resolving modeling study. Atmos. Res., 91, 94-104.] are used as the control experiment. The difference between the control and sensitivity experiments is that vertically varying zonal winds in the control experiment are replaced by their mass-weighted means in the sensitivity experiment. The imposed vertical velocity with ascending motion in the upper troposphere and descending motion in the lower troposphere is responsible for dominant stratiform rainfall on 15 July. The vertical wind shear does not have important impacts on development of stratiform rainfall. One day later, imposed upward motion extends to the lower troposphere. The inclusion of negative vertical wind shear produces well-organized convection and strong convective rainfall because it causes kinetic energy transfer from large-scale forcing to perturbation circulations.

Wang, Donghai; Li, Xiaofan; Tao, Wei-Kuo; Wang, Yuan

2009-10-01

74

A study of the relationship between certain moisture parameters and severe convective storms in central Oklahoma  

E-print Network

for 1800 CST ?6 April 1970. 29 11. LPW chart (from 1934-2000 CST) 26 April 1970. . . 12. UPW chart (from 1934-2000 CST) 26 April 1970. . . 13. Plot for 0' tilt angle for 1815 CST 26 April 1970. . . 30 31 33 14. Plot of PVIL centers for the storm... storm events associated with the storm system on this evening, but the one of interest occurred, according to Storm Data, at Lawton, Oklahoma, 61 nm southwest of the NSSL radar site at 1815 CST. Gusty winds estimated at 70 kts turned over...

Scott, Carven Allen

1977-01-01

75

Numerical Simulation and Diagnostic Analysis of a Severe Convective Storm Process with Tornado1  

Microsoft Academic Search

Severe convective weather is serious disastrous weather . It has such features as small spatial scale, short life span, abrupt occurrence and large destructive power. Due to the features, it is difficulty to predict strong convective weathers. Many scientists have investigated this issue. Along with the various improvements of meso-scale models and study of local strong convections, scientists have found

Shou Shaowen; Zhang Lin

76

The vertical profile of radar reflectivity of convective cells: A strong indicator of storm intensity and lightning probability?  

NASA Technical Reports Server (NTRS)

Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSs) in three different environmental regimes. The National Center for Atmospheric Research CP-3 and CP-4 radars are used to calculate median VPRR for MCSs in the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central in 1985. The National Oceanic and Atmospheric Administration-Tropical Ocean Global Atmosphere radar in Darwin, Australia, is used to calculate VPRR for MCSs observed both in oceanic, monsoon regimes and in continental, break period regimes during the wet seasons of 1987/88 and 1988/89. The midlatitude and tropical continental VPRRs both exhibit maximum reflectivity somewhat above the surface and have a gradual decrease in reflectivity with height above the freezing level. In sharp contrast, the tropical oceanic profile has a maximum reflectivity at the lowest level and a very rapid decrease in reflectivity with height beginning just above the freezing level. The tropical oceanic profile in the Darwin area is almost the same shape as that for two other tropical oceanic regimes, leading to the conclustion that it is characteristic. The absolute values of reflectivity in the 0 to 20 C range are compared with values in the literature thought to represent a threshold for rapid storm electrification leading to lightning, about 40 dBZ at -10 C. The large negative vertical gradient of reflectivity in this temperature range for oceanic storms is hypothesized to be a direct result of the characteristically weaker vertical velocities observed in MCSs over tropical oceans. It is proposed, as a necessary condition for rapid electrification, that a convective cell must have its updraft speed exceed some threshold value. Based upon field program data, a tentative estimate for the magnitude of this threshold is 6-7 m/s for mean speed and 10-12 m/s for peak speed.

Zipser, Edward J.; Lutz, Kurt R.

1994-01-01

77

Evaluate the urban effect on summer convective precipitation by coupling a urban canopy model with a Regional Climate Model  

NASA Astrophysics Data System (ADS)

One of the most significant urbanization in the world occurred in Great Beijing Area of China during the past several decades. The land use and land cover changes modifies the land surface physical characteristics, including the anthropogenic heat and thermo-dynamic conduction. All of those play important roles in the urban regional climate changes. We developed a single layer urban canopy module based on the Community Land Surface Model Urban Module (CLMU). We have made further improvements in the urban module: the energy balances on the five surface conditions are considered separately: building roof, sun side and shade side wall, pervious and impervious land surface. Over each surface, a method to calculate sky view factor (SVF) is developed based on the physically process while most urban models simply provide an empirical value; A new scheme for calculating the latent heat flux is applied on both wall and impervious land; anthropogenic heat is considered in terms of industrial production, domestic wastes, vehicle and air condition. All of these developments improve the accuracy of surface energy balance processing in urban area. The urban effect on summer convective precipitation under the unstable atmospheric condition in the Great Beijing Area was investigated by simulating a heavy rainfall event in July 21st 2012. In this storm, strong meso-scale convective complexes (MCC) brought precipitation of averagely 164 mm within 6 hours, which is the record of past 60 years in the region. Numerical simulating experiment was set up by coupling MCLMU with WRF. Several condition/blank control cases were also set up. The horizontal resolution in all simulations was 2 km. While all of the control results drastically underestimate the urban precipitation, the result of WRF-MCLMU is much closer to the observation though still underestimated. More sensitive experiments gave a preliminary conclusion of how the urban canopy physics processing affects the local precipitation: the existence of large area of impervious surfaces restrain the surface evaporation and latent heat flux in urban while the anthropogenic heat and enhanced sensible heat flux warm up the lower atmospheric layer and strengthen the vertical stratification instability; In this storm event, the water supply of the MCC was thought to be sufficient, thus the instability of the vertical stratification was the key factor for precipitation.

Liu, Z.; Liu, S.; Xue, Y.; Oleson, K. W.

2013-12-01

78

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land and Its Microphysical Implications  

NASA Technical Reports Server (NTRS)

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-POL) radar from two field experiments are used to evaluate the Surface ref'ercnce technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in vxo deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at. the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and dry ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level, and that the data are not readil explained in terms of a gamma function raindrop size distribution.

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; Starr, D. OC. (Technical Monitor)

2001-01-01

79

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land Its Microphysical Implications  

NASA Technical Reports Server (NTRS)

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-Pol) radar from two field experiments are used to evaluate the surface reference technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in two deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and (dry) ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level.

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; O'C.Starr, D. (Technical Monitor)

2001-01-01

80

Satellite detection of severe convective storms by their retrieved vertical profiles of cloud particle effective radius and thermodynamic phase  

NASA Astrophysics Data System (ADS)

A new conceptual model that facilitates the inference of the vigor of severe convective storms, producing tornadoes and large hail, by using satellite-retrieved vertical profiles of cloud top temperature (T)-particle effective radius (re) relations is presented and tested. The driving force of these severe weather phenomena is the high updraft speed, which can sustain the growth of large hailstones and provide the upward motion that is necessary to evacuate the violently converging air of a tornado. Stronger updrafts are revealed by the delayed growth of re to greater heights and lower T, because there is less time for the cloud and raindrops to grow by coalescence. The strong updrafts also delay the development of a mixed phase cloud and its eventual glaciation to colder temperatures. Analysis of case studies making use of these and related criteria show that they can be used to identify clouds that possess a significant risk of large hail and tornadoes. Although the strength and direction of the wind shear are major modulating factors, it appears that they are manifested in the updraft intensity and cloud shapes and hence in the T-re profiles. It is observed that the severe storm T-re signature is an extensive property of the clouds that develop ahead in space and time of the actual hail or tornadic storm, suggesting that the probabilities of large hail and tornadoes can be obtained at substantial lead times. Analysis of geostationary satellite time series indicates lead times of up to 2 h.

Rosenfeld, Daniel; Woodley, William L.; Lerner, Amit; Kelman, Guy; Lindsey, Daniel T.

2008-02-01

81

The vertical profile of radar reflectivity of convective cells: A strong indicator of storm intensity and lightning probability?  

SciTech Connect

Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSs) in three different environmental regimes. The National Center for Atmospheric Research CP-3 and CP-4 radars are used to calculate median VPRR for MCSs in the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central in 1985. The National Oceanic and Atmospheric Administration-Tropical Ocean Global Atmosphere radar in Darwin, Australia, is used to calculate VPRR for MCSs observed both in oceanic, monsoon regimes and in continental, break period regimes during the wet seasons of 1987/88 and 1988/89. The midlatitude and tropical continental VPRRs both exhibit maximum reflectivity somewhat above the surface and have a gradual decrease in reflectivity with height above the freezing level. In sharp contrast, the tropical oceanic profile has a maximum reflectivity at the lowest level and a very rapid decrease in reflectivity with height beginning just above the freezing level. The tropical oceanic profile in the Darwin area is almost the same shape as that for two other tropical oceanic regimes, leading to the conclustion that it is characteristic. The absolute values of reflectivity in the 0 to 20 C range are compared with values in the literature thought to represent a threshold for rapid storm electrification leading to lightning, about 40 dBZ at -10 C. The large negative vertical gradient of reflectivity in this temperature range for oceanic storms is hypothesized to be a direct result of the characteristically weaker vertical velocities observed in MCSs over tropical oceans..

Zipser, E.J.; Lutz, K.R. [Texas A& M Univ., College Station, TX (United States)] [Texas A& M Univ., College Station, TX (United States)

1994-08-01

82

A two year (2008-2009) analysis of severe convective storms in the Mediterranean basin as observed by satellite imagery  

NASA Astrophysics Data System (ADS)

The increasing damages caused by natural disasters, a great part of them being direct or indirect effects of severe convective storms (SCS), seem to suggest that extreme events occur with greater frequency, also as a consequence of climate changes. A better comprehension of the genesis and evolution of SCS is then necessary to clarify if and what is changing in these extreme events. The major reason to go through the mechanisms driving such events is given by the growing need to have timely and precise predictions of severe weather events, especially in areas that show to be more and more sensitive to their occurrence. When dealing with severe weather events, either from a researcher or an operational point of view, it is necessary to know precisely the conditions under which these events take place to upgrade conceptual models or theories, and consequently to improve the quality of forecasts as well as to establish effective warning decision procedures. The Mediterranean basin is, in general terms, a sea of small areal extent, characterised by the presence of several islands; thus, a severe convection phenomenon originating over the sea, that lasts several hours, is very likely to make landfall during its lifetime. On the other hand, these storms are quasi-stationary or very slow moving so that, when convection happens close to the shoreline, it is normally very dangerous and in many cases can cause very severe weather, with flash floods or tornadoes. An example of these extreme events is one of the case study analysed in this work, regarding the flash flood occurred in Giampileri (Sicily, Italy) the evening of 1st October 2009, where 18 people died, other 79 injured and the historical centre of the village seriously damaged. Severe weather systems and strong convection occurring in the Mediterranean basin have been investigated for two years (2008-2009) using geostationary (MSG) and polar orbiting (AVHRR) satellite data, supported by ECMWF analyses and severe weather reports. The spatial and seasonal variability of storm occurrence have been also analysed, as well as the most favourable synoptic conditions for their formation. The analysis shows the existence of preferential areas of genesis of these extreme events, mainly located in the central Mediterranean (i.e., Ionic and Tyrrhenian seas), where the storms develop and grow preferentially in fall. The synoptic features, identified as precursors of severe convective events genesis, show how the totality of the identified cases occur in mid-troposphere (500 hPa) troughs or cut-off circulation within southerly flow, with values of deep level shear of at least 15 m s-1 and high ?e (850 hPa) values. Among all the detected cases of severe convection, two selected cases of enhanced-V features are presented in detail, either for the different synoptic environments in which they are embedded, and for being long-lived or severe in terms of heavy rainfall and damages they produced at the ground. In a long-term perspective, this preliminary study aims to make a climatological database of severe weather events occurring in the Mediterranean sea which may critically impact on the Italian peninsula and potentially affect population, in order to develop an objective procedure which can support regional meteorological services in forecasting extreme events, their development and impact, for taking proper early decisions.

Gozzini, B.; Melani, S.; Pasi, F.; Ortolani, A.

2010-09-01

83

THE CONDITIONAL RISK OF SEVERE CONVECTION ESTIMATED FROM ARCHIVED NWS\\/STORM PREDICTION CENTER MESOSCALE OBJECTIVE ANALYSES: POTENTIAL USES IN SUPPORT OF FORECAST OPERATIONS AND VERIFICATION  

Microsoft Academic Search

-1 ) or damage consistent with such wind speeds, or tornadoes) as a function of convective available potential energy (CAPE) and deep-layer (0-6 km) bulk shear. We have also populated a 5-dimensional parameter space that includes CAPE, convective inhibition (CIN), deep-layer shear, 0-1 km storm-relative helicity (SRH1) and lifting condensation level (LCL) height in order to develop a multi-parameter estimate

Andrew R. Dean; Russell S. Schneider; Richard L. Thompson; John Hart

84

Responses of vertical structures in convective and stratiform regions to large-scale forcing during the landfall of severe tropical storm Bilis (2006)  

Microsoft Academic Search

The responses of vertical structures, in convective and stratiform regions, to the large-scale forcing during the landfall\\u000a of tropical storm Bilis (2006) are investigated using the data from a two-dimensional cloud-resolving model simulation. An\\u000a imposed large-scale forcing with upward motion in the mid and upper troposphere and downward motion in the lower troposphere\\u000a on 15 July suppresses convective clouds, which

Donghai Wang; Xiaofan Li; Wei-Kuo Tao

2010-01-01

85

The Storms of SummerLessons Learned in the Aftermath of the Hurricanes of '04  

Microsoft Academic Search

Unlike the hoteliers chronicled in the accompanying report on the blackout of '03, the Walt Disney World® Resort did not face an electrical blackout when three hurricanes passed through Florida during the hurricane season of 2004. However, the dangerous storms forced Walt Disney World to suspend operations and ask guests to remain in their hotel rooms. The storms' violence also

Barbara A. Higgins

2005-01-01

86

A storm modeling system as an advanced tool in prediction of well organized slowly moving convective cloud system and early warning of severe weather risk  

NASA Astrophysics Data System (ADS)

Short-range prediction of precipitation is a critical input to flood prediction and hence the accuracy of flood warnings. Since most of the intensive processes come from convective clouds-the primary aim is to forecast these small-scale atmospheric processes. One characteristic pattern of organized group of convective clouds consist of a line of deep convection resulted in the repeated passage of heavy-rain-producing convective cells over NW part of Macedonia along the line. This slowly moving convective system produced extreme local rainfall and hailfall in urban Skopje city. A 3-d cloud model is used to simulate the main storm characteristic (e.g., structure, intensity, evolution) and the main physical processes responsible for initiation of heavy rainfall and hailfall. The model showed a good performance in producing significantly more realistic and spatially accurate forecasts of convective rainfall event than is possible with current operational system. The output results give a good initial input for developing appropriate tools such as flooding indices and potential risk mapping for interpreting and presenting the predictions so that they enhance operational flood prediction capabilities and warnings of severe weather risk of weather services. Convective scale model-even for a single case used has proved significant benefits in several aspects (initiation of convection, storm structure and evolution and precipitation). The storm-scale model (grid spacing-1 km) is capable of producing significantly more realistic and spatially accurate forecasts of convective rainfall events than is possible with current operational systems based on model with grid spacing 15 km.

Spiridonov, Vlado; Curic, Mladjen

2015-02-01

87

Origin of the pre-tropical storm Debby (2006) African easterly wave-mesoscale convective system  

NASA Astrophysics Data System (ADS)

The origins of the pre-Debby (2006) mesoscale convective system (MCS) and African easterly wave (AEW) and their precursors were traced back to the southwest Arabian Peninsula, Asir Mountains (AS), and Ethiopian Highlands (EH) in the vicinity of the ITCZ using satellite imagery, GFS analysis data and ARW model. The sources of the convective cloud clusters and vorticity perturbations were attributed to the cyclonic convergence of northeasterly Shamal wind and the Somali jet, especially when the Mediterranean High shifted toward east and the Indian Ocean high strengthened and its associated Somali jet penetrated farther to the north. The cyclonic vorticity perturbations were strengthened by the vorticity stretching associated with convective cloud clusters in the genesis region—southwest Arabian Peninsula. A conceptual model was proposed to explain the genesis of convective cloud clusters and cyclonic vorticity perturbations preceding the pre-Debby (2006) AEW-MCS system.

Lin, Yuh-Lang; Liu, Liping; Tang, Guoqing; Spinks, James; Jones, Wilson

2013-05-01

88

Summer season land cover—Convective cloud associations for the midwest U.S. “Corn Belt”  

NASA Astrophysics Data System (ADS)

Human-induced land cover modifications impact the planetary boundary layer's (PBL) thermal and moisture regimes on mesoscales. We investigate the association of croplands, forest, and the crop-forest “boundary” (CFB) with convective-cloud development (timing, amount) for three target areas (TAs) in the U.S. Midwest “Corn Belt”, during the summer seasons (JJA) 1991-98. For each land cover, hourly satellite-retrieved albedo and cloud-top temperature values are composited for three classes of mid-tropospheric synoptic circulation. On days with the strongest anticyclonicity, there are no consistent differences in convection related to land cover type: cloud development is regionalized and tied primarily to synoptic conditions. However, on days having weaker anticyclonicity the CFB is the dominant site of free convection, suggesting that Non-Classical Mesoscale Circulations (NCMCs) between cropped and adjacent forest areas may operate when reduced subsidence in the mid-troposphere does not effectively cap the PBL. Index terms: Land/atmosphere interactions (3322), Mesoscale meteorology (3329), Climate dynamics (1620), Anthropogenic effects (1803).

Carleton, Andrew M.; Adegoke, Jimmy; Allard, Jason; Arnold, David L.; Travis, David J.

89

Infrasound From Convective Storms: An Experimental Test of Electrical Source Mechanisms  

Microsoft Academic Search

paper reports the results of such a test. We find that the spatial and temporal correlation between the two kinds of emissions is much lower than we would expect if the two were causally related; therefore the source of severe storm infrasound is probably not electrical.

William H. Beasley; T. M. Georges; Michael W. Evans

1976-01-01

90

Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm  

E-print Network

is employed to study microphysical processes. Dual-Doppler techniques are used to analyze the 3D wind field Weather Surveil- lance Radar-1988 Doppler (WSR-88D) network of radars, given the current radar spacing is their ability to adaptively scan storms in real-time using the so-called distributed collaborative adaptive

Rutledge, Steven

91

Mesospheric concentric gravity waves generated by multiple convective storms over the North American Great Plain  

NASA Astrophysics Data System (ADS)

We report on six continuous hours of OH airglow imager observations (at z ˜ 87 km) of convectively generated gravity waves (GWs) near Fort Collins, Colorado, on the evening of 08 September 2005. These GWs appeared as nearly concentric rings, and had epicenters near the locations of deep convection in three thunderstorms in Colorado, Nebraska and South Dakota. Using GOES satellite and weather radar observations, we show that the GWs closely follow the thunderstorms. Using the background wind from a nearby radar, the intrinsic wave parameters and vertical wavelengths are calculated. The temperature perturbations are estimated to be T?/T¯ ˜ 1-3% for GWs with horizontal wavelengths ?h ˜ 20-40 km and horizontal phase speeds ˜40-60 m/s. The horizontal wavelengths of GWs from a convective cluster decreased in time from 30 to 15 km. We employ convective plume and ray-trace models to simulate the GW-induced OH intensity perturbations from convective plumes, clusters and complexes. We find that the results using the background model wind (radiosonde/TIME-GCM) agree well with the late-time observations, when the images are dominated by southwestward, short-wavelength, high-frequency GWs. These late-time GWs propagate against the background wind, and have ?h ˜ 30-40 km and periods of ? ˜ 20-30 min. The OH intensity perturbations are enhanced because the vertical wavelengths ?z increased, T?/T¯ increased, and the vertical velocity perturbations w? decreased (because the GWs were near their reflection levels). We also find that these short-wavelength GWs were created ˜5 h earlier by an extremely energetic, deep convective plume in South Dakota, thereby showing that small-scale, convective GWs directly link the troposphere and mesopause region.

Vadas, Sharon; Yue, Jia; Nakamura, Takuji

2012-04-01

92

Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm  

Microsoft Academic Search

Summary  Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes\\u000a for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme\\u000a within a meso-? scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration\\u000a is given to the model’s dynamical response to the forcing as

D. Leuenberger; A. Rossa

2007-01-01

93

Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)  

USGS Publications Warehouse

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).

Haase, K.B.; Jordan, C.; Mentis, E.; Cottrell, L.; Mayne, H.R.; Talbot, R.; Sive, B.C.

2011-01-01

94

Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)  

USGS Publications Warehouse

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.

Haase, Karl B.; Jordan, C.; Mentis, E.; Cottrell, L.; Mayne, H.R.; Talbot, R.; Sive, B.C.

2011-01-01

95

Mesospheric concentric gravity waves generated by multiple convective storms over the North American Great Plain  

E-print Network

, and had epicenters near the locations of deep convection in three thunderstorms in Colorado, Nebraska the thunderstorms. Using the background wind from a nearby radar, the intrinsic wave parameters and vertical and complexes. We find that the results using the background model wind (radiosonde/TIME-GCM) agree well

Vadas, Sharon

96

Arctic summer storm track in CMIP3/5 climate models  

NASA Astrophysics Data System (ADS)

Model performance and future projection of Arctic summertime storm-track activity and associated background states are assessed on the basis of Coupled Model Intercomparison Project Phase 3 (CMIP3)/5 (CMIP5) climate models. Despite some improvement in the CMIP5 models relative to the CMIP3 models, most of the climate models underestimate summertime storm-track activity over the Arctic Ocean compared to six reanalysis data sets as measured locally as the variance of subweekly fluctuations of sea level pressure. Its large inter-model spread (i.e., model-to-model differences) is correlated with that of the intensity of the Beaufort Sea High and the lower-tropospheric westerlies in the Arctic region. Most of the CMIP3/5 models project the enhancement of storm-track activity over the Arctic Ocean off the eastern Siberian and Alaskan coasts, the region called the Arctic Ocean Cyclone Maximum, in association with the strengthening of the westerlies in the warmed climate. A model with stronger enhancement of the storm-track activity tends to accompany stronger land-sea contrast in surface air temperature across the Siberian coast, which reflects greater surface warming over the continent and slower warming over the Arctic Ocean. Other processes, however, may also be likely to contribute to the future changes of the storm-track activity, which gives uncertainty in the projection by multiple climate models. Our analysis suggests that further clarification of those processes that influence storm-track activity over the Arctic is necessary for more reliable future projections of the Arctic climate.

Nishii, Kazuaki; Nakamura, Hisashi; Orsolini, Yvan J.

2014-07-01

97

Arctic summer storm track in CMIP3/5 climate models  

NASA Astrophysics Data System (ADS)

Model performance and future projection of Arctic summertime storm-track activity and associated background states are assessed on the basis of Coupled Model Intercomparison Project Phase 3 (CMIP3)/5 (CMIP5) climate models. Despite some improvement in the CMIP5 models relative to the CMIP3 models, most of the climate models underestimate summertime storm-track activity over the Arctic Ocean compared to six reanalysis data sets as measured locally as the variance of subweekly fluctuations of sea level pressure. Its large inter-model spread (i.e., model-to-model differences) is correlated with that of the intensity of the Beaufort Sea High and the lower-tropospheric westerlies in the Arctic region. Most of the CMIP3/5 models project the enhancement of storm-track activity over the Arctic Ocean off the eastern Siberian and Alaskan coasts, the region called the Arctic Ocean Cyclone Maximum, in association with the strengthening of the westerlies in the warmed climate. A model with stronger enhancement of the storm-track activity tends to accompany stronger land-sea contrast in surface air temperature across the Siberian coast, which reflects greater surface warming over the continent and slower warming over the Arctic Ocean. Other processes, however, may also be likely to contribute to the future changes of the storm-track activity, which gives uncertainty in the projection by multiple climate models. Our analysis suggests that further clarification of those processes that influence storm-track activity over the Arctic is necessary for more reliable future projections of the Arctic climate.

Nishii, Kazuaki; Nakamura, Hisashi; Orsolini, Yvan J.

2015-03-01

98

A case study of aerosol impacts on summer convective clouds and precipitation over northern China  

NASA Astrophysics Data System (ADS)

The emissions such as greenhouse gases, precursor gases and particulate matters may directly alter the Earth radiative budget or indirectly modify cloud and precipitation processes, and possibly induce changes in climate and the hydrological cycle at the regional to global scale. The previous publications reported a few quantitative assessments and inconsistent results on the effects of the emissions on cloud and precipitation. The aerosol properties and possible impacts on a convective precipitation case on 4 July 2008 over the urban region of northern China are investigated based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data and the Weather Research and Forecast (WRF) model coupled with Chemistry (WRF-Chem). Results show that the Aerosol Optical Depth (AOD) is over 0.9 in the study area, indicating a high concentration of aerosol pollution. The value of Angstrom exponent in the study area is larger than 1.0, indicating that the main particles in the area are industrial and biomass burning pollution aerosols with radii less than 0.25-0.5 ?m. The modeling results show that the domain-averaged precipitation amount under polluted conditions can be increased up to 17% during the whole cloud lifetime. However, the maximum rainfall rate above 30 mm/h is enhanced, whereas that below 30 mm/h is suppressed in most cloud lifetime. The differences of cloud microphysics and dynamics between polluted and clean conditions indicate that both warm and ice microphysics and updraft are suppressed at the storm's initial and dissipating stages, whereas those at the storm's mature stage are obviously enhanced under polluted conditions.

Guo, Xueliang; Fu, Danhong; Guo, Xin; Zhang, Chunming

2014-06-01

99

High resolution radiometric measurements of convective storms during the GATE experiment  

NASA Technical Reports Server (NTRS)

Using passive microwave data from the NASA CV-990 aircraft and radar data collected during the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE), an empirical model was developed relating brightness temperatures sensed at 19.35 GHz to surface rainfall rates. This model agreed well with theoretical computations of the relationship between microwave radiation and precipitation in the tropics. The GATE aircraft microwave data was then used to determine the detailed structure of convective systems. The high spatial resolution of the data permitted identification of individual cells which retained unique identities throughout their lifetimes in larger cloud masses and allowed analysis of the effects of cloud merger.

Fowler, G.; Lisa, A. S.

1976-01-01

100

Overview of ESSL's severe convective storms research using the European Severe Weather Database ESWD  

NASA Astrophysics Data System (ADS)

Severe thunderstorms constitute a major weather hazard in Europe, with an estimated total damage of 5-8 billion euros each year nowadays. Even though there is an upward trend in damage due to increases in vulnerability and possibly also due to climate change impacts, a pan-European database of severe thunderstorm reports in a homogeneous data format did not exist until a few years ago. The development of this European Severe Weather Database (ESWD) provided the final impetus for the establishment of the European Severe Storms Laboratory (ESSL) as a non-profit research organisation in 2006, after having started as an informal network in 2002. Our paper provides an overview of the first research results that have been achieved by ESSL. We start by outlining the reporting practice and quality-control procedure for the database, which has been enhanced by a major software upgrade in the fall of 2008. It becomes apparent that the state of reporting converges to a realistic description of the severe storms climatology, corroborating, for instance, earlier estimates of tornado occurrence in Europe. Nevertheless, a further rise in the number of reported events must be expected, even without the presence of any physical trends. The European tornado and damaging wind intensity distributions as a function of the Fujita scale are quantitatively similar to long-term distributions from the USA, except for a strong underreporting of weak events (F0) that still persists in Europe. In addition, the ESSL has recently proposed a new wind speed scale, the Energy- or " E-scale" which is linked to physical quantities and can be calibrated. Finally, we demonstrate the large potential of ESWD data use for forecast or nowcasting/warning verification purposes.

Dotzek, Nikolai; Groenemeijer, Pieter; Feuerstein, Bernold; Holzer, Alois M.

101

Radar Observation of Large Attenuation in Convective Storms: Implications for the Dropsize Distribution  

NASA Technical Reports Server (NTRS)

Airborne meteorological radars typically operate at attenuating wavelengths. The path integrated attenuation (PIA) can be estimated using the surface reference technique (SRT). In this method, an initial value is determined for the radar cross section of the earth surface in a rain-free area in relatively close proximity to the rain cloud. During subsequent observations of precipitation any decrease 'in the observed surface cross section from the reference value s assumed to be a result of the two-way attenuation along the propagation path. In this paper we present selected instances of high PIA observed over land by an airborne radar. The observations were taken in Brazil and Florida during TRMM (Tropical Rainfall Measurement Mission) field campaigns. We compared these observations with collocated and nearly simultaneous ground-based radar observations by an S-band radar that is not subject to significant attenuation. In this preliminary evaluation, a systematic difference in the attenuation in the two storms is attributed to a difference in the raindrop size distributions; this is supported by observations of ZDR (differential reflectivity).

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.

2000-01-01

102

Severe Storms  

NSDL National Science Digital Library

Part of the University of Illinois Weather World 2010 project, this guide uses multimedia technology and the dynamic capabilities of the web to incorporate text, colorful diagrams, animations, computer simulations, audio, and video to introduce topics and concepts in the atmospheric sciences. This module is a combination of two elements. The first is the National Oceanic and Atmospheric Administration (NOAA) Severe Storms Spotters Guide. The second is a section discussing the efforts and results of modeling severe storms. The Spotters Guide contains supplemental instructional resources and a program designed to familiarize meteorologists and advanced severe storm spotters with the building blocks of convective storm structure. The focus of the training series is the development of a thunderstorm spectrum and a discussion of the physical characteristics and severe weather potential of the various storm types in the spectrum.

2010-01-01

103

Use of satellite data for severe storm nowcasting and monitoring.  

NASA Astrophysics Data System (ADS)

The area of Poland suffers from many severe storms during summer period, with highest activity between May to September. Proper prediction and monitoring of their location, time and intensity is important task - still under investigation. On the base of selected convective case studies, possibilities and weaknesses of satellite products for severe storm nowcasting and tracing were demonstrated. Selected events were connected with tornado, hail, lightning, heavy rainfall and wind occurence. Potential improvement of operational storm warning process with the use of dedicated satellite products was discussed.

Pajek, M.

2009-09-01

104

Measurement and analysis of small-scale convective storm rainfall variability  

NASA Astrophysics Data System (ADS)

For large-scale catchment hydrology, the crucial importance of a good estimate of spatial rainfall variability is generally admitted. However, the assumption of uniform rainfall is still applied for small areas, whether they are studied as individual catchments or represent an elementary area in a distributed model. To investigate the validity of this assumption, an experiment was conducted in a small catchment (4.4 ha) in the semiarid USDA-ARS Walnut Gulch Experimental Watershed. Measurements were made with recording and non-recording raingages as well as vectopluviometers for a range of events during the 1990 monsoon season (July-September). Geostatistical analysis of the data indicated the presence of first-order drift with corresponding rainfall gradients ranging from 0.28 to 2.48 mm per 100 m with an average of 1.2 mm per 100 m. These gradients represent a 4-14% variation of the mean rainfall depth over a 100 m distance. Given these observations, the assumption of spatial rainfall uniformity in this and similar convective environments at the small watershed scale of 5 ha appears to be invalid.

Goodrich, David C.; Faurès, Jean-Marc; Woolhiser, David A.; Lane, Leonard J.; Sorooshian, Soroosh

1995-12-01

105

Skywarn Spotter Convective Basics  

NSDL National Science Digital Library

The "SKYWARN® Spotter Convective Basics" module will guide users to a basic understanding of convective storms. Through three different scenarios, you will cover reporting and proper communication of local storm reports to the National Weather Service (NWS), personal safety during these events, and field identification of convective storm hazards. After completing the scenarios, you will be given the opportunity to practice identifying storm features from a spectrum of photos.

COMET

2011-04-22

106

HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME  

E-print Network

or in tropical and arid countries. In this work, radiation, convection and conduction heat transfers radiation. Natural convection in the channel underneath drives off the residual heat. The bi: Double-skin roof; Radiation; Natural convection; Passive cooling; Solar loads. * Corresponding author

Boyer, Edmond

107

Unforced variability in summer storm track position over the past millennium  

NASA Astrophysics Data System (ADS)

Gridded past millennium climate reconstructions, encompassing the European continent (e.g. Luterbacher et al 2004), based on proxy records, have previously been generated assuming that spatial temperature covariance across the region behaves in the past in the same way as it does in the observational period. This strategy bears the risk of artificially identifying the same patterns of variability as presently observed and overlooking periodically occurring modes of internal climate variability, that are not uniformly spatio-temporally expressed. Here, we construct regional proxy composites for Europe which are not constrained by the modes of variability expressed in the 20th century, and should thus broadly represent coherent regional summer temperatures back through time, independent from present modes of variability. The proxy data set analysed was provided by the efforts of the EU 6th Framework Millennium project. Proxy data are dominated by tree ring width, density and annual height increment. Four composites are used describing summer temperatures in the Arctic, Central, Pyrenean and Alpine zones of Europe. The proxy data sets cover the period AD 1260-1996. We jointly analyse an ensemble of simulations with global climate models participating in the Climate Model Intercomparison Project (CMIP5) included in the 5th Assessment report of the Intergovernmental Panel on Climate Change (IPCC) covering the period AD 850-2005, with the above aims in mind. The climate models were driven by estimations of the main external forcings. The implementations of these forcings may vary among simulations, depending on the different estimates used and on the structure of the models themselves. We analyse three simulations (CCSM4, IPSL, MPI-ESM) that, at the time of writing, provide daily data over the period AD 850-2005 obtained with the very same model version through the whole period. The analysis of both proxy and model data allowed us to more precisely identify the behaviour of the internal climate mode identified.

Gagen, Mary; Zorita, Eduardo; McCarroll, Danny; Loader, Neil; Young, Giles; Robertson, Iain

2014-05-01

108

Improving the Knowledge of Summer Monsoon Storm Genesis on the Mumbai Region  

NASA Astrophysics Data System (ADS)

Over the Indian Subcontinent, almost 75% of the annual precipitation is expected to fall during the South Asia Monsoon (SAM) season, conventionally defined between June 1 and September 30. While precipitation patterns show a very strong spatial heterogeneity, the maximum annual values (which may exceed 4000 mm) occur in the Western Coast of Indian Peninsula. This is mainly associated with orographic forcing, in particular of the Western Ghats and the Ganges and Brahmaputra valleys. Extreme rainfall events during the SAM season may be particularly intense and long-lasting, causing great damages both in terms of life and economic losses. We aim at identifying large-scale meteorological patterns associated with the triggering of extreme rainfall events affecting the Mumbai area (approximately 18-20°N, 72.5-73.5°E), a very highly populated region (around 20 million people), during the SAM season. Seventy years of daily rainfall data are analyzed and compared to a database of damage-causing precipitations. Event days are selected with a twin-threshold function related to daily rainfall height and soil moisture content. To detect typical large-scale features, event days are compared to non-event days by analyzing MSLP, SST, and vertical wind profiles. Further, the storm-related processes are analyzed with moisture sources (via backtracing) and moisture flux convergence fields. First results on selected event days show that they are typically characterized by remote moisture sources (from S-W Arabian Sea) and increased lower level westerly winds which cause enhanced moisture flux convergence, leading to precipitable water’s enhancement.

Lomazzi, M.; Entekhabi, D.; Pinto, J. G.; Roth, G.; Rudari, R.

2009-09-01

109

The Impact on Simulated Storm Structure and Intensity of Variations in the Lifted Condensation Level and the Level of Free Convection  

NASA Technical Reports Server (NTRS)

The sensitivities of convective storm structure and intensity to changes in the altitudes of the prestorm environmental lifted condensation level and level of free convection axe studied using a full-physics three-dimensional cloud model. Matrices of simulations are conducted for a range of LCL=LFC altitudes, using a single moderately-sheared curved hodograph trace in conjunction with 1 convective available potential energy values of either 800 or 2000 J/kg, with the matrices consisting of all four combinations of two distinct choices of buoyancy and shear profile shape. For each value of CAPE, the LCL=LFC altitudes are also allowed to vary in a series of simulations based on the most highly compressed buoyancy and shear profiles for that CAPE, with the environmental buoyancy profile shape, subcloud equivalent potential temperature, subcloud lapse rates of temperature and moisture, and wind profile held fixed. For each CAPE, one final simulation is conducted using a near optimal LFC, but a lowered LCL, with a neutrally buoyant environmental thermal profile specified in between. Results show that, for the buoyancy-starved small-CAPE environments, the simulated storms are supercells and are generally largest and most intense when LCL=LFC altitudes lie in the approximate range 1.5-2.5 km above the surface. The simulations show similar trends for the shear-starved large-CAPE environments, except that conversion from supercell to multicell morphology frequently occurs when the LCL is high. For choices of LCL=LFC height within the optimal 1.5-2.5 km range, peak storm updraft overturning efficiency may approaches unity relative to parcel theory, while for lower LCL=LFC heights, overturning efficiency is reduced significantly. The enhancements of overturning efficiency and updraft diameter with increasing LFC height are shown to be the result of systematic increases in the mean equivalent potential temperature of the updraft at cloud base. For the shear-starved environments, the tendency for outflow dominance is eliminated, but a large overturning efficiency maintained, when a low LCL is used in conjunction with a high LFC. The result regarding outflow dominance at high LCL is consistent with expectations, but the beneficial effect of a high LFC on convective overturning efficiency has not previously been widely recognized. The simulation findings here also appear to be consistent with statistics from previous severe storm environment climatologies, but provide a new framework for interpreting those statistics.

McCaul, Eugene W., Jr.; Cohen, Charles; Arnold, James E. (Technical Monitor)

2001-01-01

110

11A.2 Forecasting Short Term Convective Mode And Evolution For Severe Storms Initiated Along Synoptic Boundaries  

E-print Network

have been shown to be discriminators for supercell versus non-supercell modes (e.g. Weisman and Klemp. Introduction Forecasting convective mode (discrete cells versus lines) and evolution continue to represent a correct anticipation of convective organization and evolution. Historically, buoyancy and vertical shear

111

Automated radar identification, measurement of parameters, and classification of convective cells for hail protection and storm warning  

Microsoft Academic Search

Methods, algorithms, and programs of automated radar identification of convective cells in cumulonimbus clouds are considered,\\u000a that provides the ability to measure the parameters of convective cells, to plot the graphs of the time course of parameters,\\u000a to compute the direction and speed of the movement, to assess their thunderstorm and hail danger, and to recognize the categories\\u000a of target

M. T. Abshaev; A. M. Abshaev; A. M. Malkarova; M. V. Zharashuev

2010-01-01

112

Lightning location relative to storm structure in a leading-line, trailing-stratiform mesoscale convective system  

Microsoft Academic Search

Horizontal and line-normal, vertical cross-sections and composite images of Dallas-Fort Worth Lightning Detection and Ranging (LDAR II) VHF radiation sources and radar reflectivity over a 30-min period provide a unique perspective on lightning pathways within a leading-line, trailing-stratiform (LLTS) mesoscale convective system (MCS) on 16 June 2002. The overwhelming majority of VHF lightning sources occurred within the leading convective line

Lawrence D. Carey; Martin J. Murphy; Tracy L. McCormick; Nicholas W. S. Demetriades

2005-01-01

113

Contribution of the MODIS instrument to observations of deep convective storms and stratospheric moisture detection in GOES and MSG imagery  

Microsoft Academic Search

Past studies based on the NOAA\\/AVHRR and GOES I-M imager instruments have documented the link between certain storm top features referred to as the “cold-U\\/V” shape in the 10–12 ?m IR band imagery and plumes of increased 3.7\\/3.9 ?m band reflectivity. Later, similar features in the 3.7\\/3.9 ?m band have been documented in the AVHRR\\/3 1.6 ?m band imagery.The present work focuses on storm

Martin Setvák; Robert M. Rabin; Pao K. Wang

2007-01-01

114

Effects of acid deposition on dissolution of carbonate stone during summer storms in the Adirondack Mountains, New York, 1987-89  

USGS Publications Warehouse

This study is part of a long-term research program designed to identify and quantify acid rain damage to carbonate stone. Acidic deposition accelerates the dissolution of carbonate-stone monuments and building materials. Sequential sampling of runoff from carbonate-stone (marble) and glass (reference) microcatchments in the Adirondack Mountains in New York State provided a detailed record of the episodic fluctuations in rain rate and runoff chemistry during individual summer storms. Rain rate and chemical concentrations from carbonate-stone and glass runoff fluctuated three to tenfold during storms. Net calcium-ion concentrations from the carbonatestone runoff, a measure of stone dissolution, typically fluctuated twofold during these storms. High net sulfate and net calcium concentrations in the first effective runoff at the start of a storm indicated that atmospheric pollutants deposited on the stone surface during dry periods formed calcium sulfate minerals, an important process in carbonate stone dissolution. Dissolution of the carbonate stone generally increased up to twofold during coincident episodes of low rain rate (less than 5 millimeters per hour) and decreased rainfall (glass runoff) pH (less than 4.0); episodes of high rain rate (cloudbursts) were coincident with a rapid increase in rainfall pH and also a rapid decrease in the dissolution of carbonate-stone. During a storm, it seems the most important factors causing increased dissolution of carbonate stone are coincident periods of low rain rate and decreased rainfall pH. Dissolution of the carbonate stone decreased slightly as the rain rate exceeded about 5 millimeters per hour, probably in response to rapidly increasing rainfall pH during episodes of high rain rate and shorter contact time between the runoff and the stone surface. High runoff rates resulting from cloudbursts remove calcium sulfate minerals formed during dry periods prior to storms and also remove dissolution products formed in large measure by chemical weathering as a result of episodes of low rain rate and decreased rainfall pH during a storm.

Schuster, Paul F.; Reddy, Michael M.; Sherwood, S.I.

1994-01-01

115

Arctic Storms and Their Links to Surface Energy Budget Changes at the Onset and End of the Summer Melt Season Over Pack Ice  

NASA Astrophysics Data System (ADS)

The length of the Arctic melt season has been observed to be increasing over the last two decades. However, the processes which initiate and end the summer melt season have not been studied in detail. Point observations at the Surface Heat Budget of the Arctic Ocean (SHEBA) site during the summer of 1998 suggest that Arctic storms over the pack ice at both ends of the melt season alter all of the terms of the surface energy budget, leading to the onset and end of the summer melt in late May or June and August, respectively. In particular, changes in longwave radiative conditions from clouds located in warm or cold air masses aloft produce key changes to the surface energy budget. This presentation will show these observations and examine the generality of the hypothesis using data from the Russian drifting stations, the North Pole Environmental Observatories, and Arctic Ocean Expedition-2001. The synoptic environment of the freeze-up process will be demonstrated with preliminary data from the recently completed Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA) and Arctic Summer Cloud-Ocean Study (ASCOS) field programs.

Persson, O. P.; Solomon, A.; Shupe, M.; Gasiewski, A. J.

2008-12-01

116

Synoptic pattern and severe weather associated with the wide convection over Southeast China during the summer monsoon period  

NASA Astrophysics Data System (ADS)

Based on the Tropical Rainfall Measuring Mission (TRMM) precipitation radar observations, wide convection (WC) is defined as contiguous convective echoes over 40 dBZ, accompanied with a near surface rainfall area exceeding 1000 km2. In Southeast China, the maximal occurrence frequency of WC takes place over the flat land region in the central plain of East China during the summer monsoon period of 1998-2010. When WC occurs in this region, the 500-hPa atmospheric fields are categorized into three patterns by using an objective classification method, i.e., the deep-trough-control (DTr) pattern, the subtropical-high-maintenance (STH) pattern, and the typhoon-effect (Typh) pattern, which respectively accounts for 20.8%, 52.8%, and 26.4% of the total WC occurrences. The DTr pattern starts to emerge the earliest (16-31 May) and occurs the most often in the second half of June; the STH pattern has a significant occurrence peak in the first half of July; the Typh pattern occurs mostly in July and August. Nearly all WC occurrences in this region are associated with thunderstorms, due to large convective available potential energy and abundant moisture. Among the three synoptic patterns, the DTr pattern features the driest and coldest air in the region, leading to the least occurrences of short-duration heavy rainfall. Strong winds occur the most often under the DTr pattern, probably owing to the largest difference in air humidity between the mid and low troposphere. Hail at the surface is rare for all occurrences of WC, which is probably related to the humid environmental air under all weather patterns and the high (> 5 km) freezing level under the STH pattern.

Wang, Hui; Luo, Yali; Zhang, Renhe

2015-02-01

117

The influence of Nunataks on atmospheric boundary layer convection during summer in Dronning Maud Land, Antarctica  

NASA Astrophysics Data System (ADS)

The effects of nunataks on temperature profiles and wind patterns are studied using simulations from the Weather Research and Forecasting model. Simulations are compared to hourly observations from an automatic weather station located at the Troll Research Station in Dronning Maud Land. Areas of bare ground have been implemented in the model, and the simulations correspond well with meteorological measurements acquired during the 4 day simulation period. The nunataks are radiatively heated during daytime, and free convection occurs in the overlying atmospheric boundary layer. The inflow below the updraft forces strong horizontal convergence at the surface, whereas weaker divergence appears aloft. In a control run with a completely ice-covered surface, the convection is absent. In situ observations carried out by a remotely controlled balloon and a small model airplane compare well with model temperature profiles, but these are only available over the ice field upwind to the nunatak.

Stenmark, Aurora; Hole, Lars Robert; Voss, Paul; Reuder, Joachim; Jonassen, Marius O.

2014-06-01

118

Summer convection and lightning over the Mackenzie river basin and their Impacts during 1994 and 1995  

Microsoft Academic Search

Lightning activity over the Mackenzie basin has been examined for the summers of 1994 and 1995. In recent years, the lightning network operating in the Northwest Territories has detected an average of 118 K strikes per season. Positive lightning strikes (defined as lightning discharges lowering positive charge to the earth) typically comprise 12% of the total. The lightning activity during

B. Kochtubajda; R. E. Stewart; J. R. Gyakum; M. D. Flannigan

2002-01-01

119

Factors Influencing the Development and Maintenance of Nocturnal Heavy-Rain-Producing Convective Systems in a Storm-Scale Ensemble  

E-print Network

&M University, College Station, Texas, and Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado ADAM J. CLARK Cooperative Institute for Mesoscale Meteorological Studies, University 2012, in final form 11 January 2013) ABSTRACT From 9 to 11 June 2010, a mesoscale convective vortex

Xue, Ming

120

Case studies of sprite-producing and non-sprite-producing summer thunderstorms  

NASA Astrophysics Data System (ADS)

Three summer thunderstorms in the eastern region of China were analyzed in detail using multiple data, including Doppler radar, lightning location network, TRMM (Tropical Rainfall Measuring Mission), MTSAT (Multi-Function Transport Satellite) images, NCEP (National Centers for Environmental Prediction) Reanalysis, and radiosonde. Two of the three storms were sprite-producing and the other was non-spriteproducing. The two sprite-producing storms occurred on 1-2 August and 27-28 July 2007, producing 16 and one sprite, respectively. The non-sprite-producing storm occurred on 29-30 July 2007. The major objective of the study was to try to find possible differences between sprite-producing and non-sprite producing storms using the multiple datasets. The results showed that the convection in the 1-2 August storm was the strongest compared with the other storms, and it produced the largest number of sprites. Precipitation ice, cloud ice and cloud water content in the convective regions in the 1-2 August storm were larger than in the other two storms, but the opposite was true in the weak convective regions. The storm microphysical properties along lines through parent CG (cloud-to-ground lightning) locations showed no special characteristics related to sprites. The flash rate evolution in the 1-2 August storm provided additional confirmation that major sprite activity coincides with a rapid decrease in the negative CG flash rate. However, the evolution curve of the CG flash rate was erratic in the sprite-producing storm on 27-28 July, which was significantly different from that in the 1-2 August storm. The average positive CG peak current in sprite-producing storms was larger than that in the non-sprite-producing one.

Yang, Jing; Yang, Meirong; Liu, Chao; Feng, Guili

2013-11-01

121

Thyroid storm  

MedlinePLUS

Thyrotoxic storm; Hyperthyroid storm; Accelerated hyperthyroidism ... Thyroid storm occurs in people with untreated hyperthyroidism. It is usually brought on by a major stress such as trauma, heart attack, or infection. Thyroid storm is very rare.

122

What is a geomagnetic storm?  

Microsoft Academic Search

The authors present a review of geomagnetic storm research. They examine the interaction of the solar wind with the magnetosphere. They argue that a storm results from the extended interaction of the solar wind\\/magnetosphere when a strong convection electric field is generated, which is able to perturb the ring current above some threshold level, triggering the event. They touch on

W. D. Gonzales; J. A. Joselyn; Y. Kamide; H. W. Kroehl; G. Rostoker; B. T. Tsurutani; V. M. Vasyliunas

1994-01-01

123

Boreal summer intraseasonal variability simulated in the NCEP climate forecast system: insights from moist static energy budget and sensitivity to convective moistening  

NASA Astrophysics Data System (ADS)

The NCEP Climate Forecast System (CFS) with the relaxed Arakawa Schubert (RAS, hereafter referred to as CTRL) convection scheme of Moorthi and Suarez exhibits better performance in representing boreal summer tropical intraseasonal variability as compared with a simulation using simplified Arakawa-Schubert scheme. The intraseasonal moist static energy (MSE) budget is analyzed in this version of the CFS model (CTRL), which produces realistic eastward and northward propagation characteristics. The moist and thermodynamic processes involved in the maintenance and propagation of the poleward moving intraseasonal oscillation (ISO) disturbances are examined here. Budget diagnostics show that horizontal MSE advection is the principal component of the budget, contributing to the poleward movement of the convection. The injection of MSE moistens the atmosphere north of the convective area causing the poleward movement of convection by destabilization of the atmosphere. The moistening process is mainly contributed by the climatological wind acting on the anomalous moisture gradient as confirmed from the examination of moisture advection equation. While surface enthalpy fluxes (consisting of radiative and surface turbulent heat fluxes) maintain the ISO anomalies, they oppose the MSE tendency due to horizontal advection thus regulating the poleward propagation characteristics. In addition, the model results show that wind-evaporation feedback dominates over cloud-radiation feedback for ISO propagation; this is in contrast to our estimates using the newly available European Centre for Medium Range Weather Forecasts Interim reanalysis. Sensitivity experiments suggest that intraseasonal variability in the CFS model with the RAS scheme is highly sensitive to the parameterization of both the shallow convection and the convective rain evaporation and downdrafts. Removal of these components adversely affects the propagation characteristics and greatly reduces the amplitude of intraseasonal variability. Our results support the primary importance of the moisture preconditioning ahead of the ISO and the physical relationship between moisture and precipitation. For realistic ISO simulations, models need to represent these features appropriately.

Sooraj, K. P.; Seo, Kyong-Hwan

2013-09-01

124

Evaluating storm-scale groundwater recharge dynamics with coupled weather radar data and unsaturated zone modeling  

NASA Astrophysics Data System (ADS)

Groundwater recharge rates through the unsaturated zone emerge from complex interactions within the soil-vegetation-atmosphere system that derive from nonlinear relationships amongst atmospheric boundary conditions, plant water use and soil hydraulic properties. While it is widely recognized that hydrologic models must capture soil water dynamics in order to provide reliable recharge estimates, information on episodic recharge generation remains uncommon, and links between storm-scale weather patterns and their influence on recharge is largely unexplored. In this study, the water balance of a heterogeneous one-dimensional soil domain (3 m deep) beneath a typical rainfed corn agro-ecosystem in eastern Nebraska was numerically simulated in HYDRUS-1D for 12 years (2001-2012) on hourly time steps in order to assess the relationships between weather events and episodic recharge generation. WSR-88D weather radar reflectivity data provided both rainfall forcing data (after estimating rain rates using the z/r ratio method) and a means of storm classification on a scale from convective to stratiform using storm boundary characteristics. Individual storm event importance to cumulative recharge generation was assessed through iterative scenario modeling (773 total simulations). Annual cumulative recharge had a mean value of 9.19 cm/yr (about 12 % of cumulative rainfall) with coefficient of variation of 73%. Simulated recharge generation events occurred only in late winter and spring, with a peak in May (about 35% of total annual recharge). Recharge generation is observed primarily in late spring and early summer because of the combination of high residual soil moisture following a winter replenishment period, heavy convective storms, and low to moderate potential evapotranspiration rates. During the growing season, high rates of root water uptake cause rapid soil water depletion, and the concurrent high potential evapotranspiration and low soil moisture prevented recharge generation until late winter, even when intense convective storms took place. For this reason, about 86% of all precipitation events produce insignificant recharge contributions. Recharge responses to individual storms were nonlinear and did not cluster well with either storm amount or storm classification type. For example, ~7% of rainfall events fall near the 1:1 rainfall/recharge line and these events represent about 37% of cumulative recharge, and individual storms accounted for up to 4% of their annual totals. However, recharge events in late winter are mainly triggered by stratiform precipitation whereas in spring they are generally generated by convective storms. This novel approach to assessing storm-scale recharge may be relevant to several current challenges in the characterization of groundwater recharge processes, including the evaluation of their spatiotemporal distributions and the impacts of climate change on groundwater.

Nasta, P.; Gates, J. B.; Lock, N.; Houston, A. L.

2013-12-01

125

Export mechanisms for dissolved organic carbon and nitrate during summer storm events in a glaciated forested catchment in New York, USA  

NASA Astrophysics Data System (ADS)

Nitrate and dissolved organic carbon (DOC) concentrations during a summer storm for a forested catchment in the Adirondack Mountains displayed a clear separation in trajectories and timing of maximum values. Nitrate concentrations peaked early on the rising limb of the hydrograph, whereas DOC concentrations gradually increased through the rising limb with maximum concentrations following the discharge peak. Solute data from precipitation, throughfall, soilwater, and ground/till water indicated till water and near-surface soil waters as the controlling end members for stream NO3- and DOC concentrations respectively. Streamflow concentrations of major base cations (Ca2+ and Mg2+), which were assumed to represent water originating from deep flow paths, matched the NO3- trajectory. These data suggest that streamflow NO3- concentrations are derived from till groundwater and that DOC is derived from near-surface soil waters. We attributed the early expression of NO3- to the displacement of till waters by infiltrating precipitation. In contrast, we hypothesized that the delayed DOC concentrations occurred with surface and near-surface runoff from near-stream wetlands/peatlands and isolated saturated areas that became connected only under conditions of maximum water content in the catchment.

Inamdar, Shreeram P.; Christopher, Sheila F.; Mitchell, Myron J.

2004-10-01

126

The impact of revised simplified Arakawa-Schubert convection parameterization scheme in CFSv2 on the simulation of the Indian summer monsoon  

NASA Astrophysics Data System (ADS)

Keeping the systematic bias of the climate forecast system model version 2 (CFSv2) in mind, an attempt is made to improve the Indian summer monsoon (ISM) rainfall variability in the model from diurnal through daily to seasonal scale. Experiments with default simplified Arakawa-Schubert (SAS) and a revised SAS schemes are carried out to make 15 years climate run (free run) to evaluate the model fidelity with revised SAS as compared to default SAS. It is clearly seen that the revised SAS is able to reduce some of the biases of CFSv2 with default SAS. Improvement is seen in the annual seasonal cycle, onset and withdrawal but most importantly the rainfall probability distribution function (PDF) has improved significantly. To understand the reason behind the PDF improvement, the diurnal rainfall simulation is analysed and it is found that the PDF of diurnal rainfall has significantly improved with respect to even a high resolution CFSv2 T382 version. In the diurnal run with revised SAS, the PDF of rainfall over central India has remarkably improved. The improvement of diurnal cycle of total rainfall has actually been contributed by the improvement of diurnal cycle of convection and associated convective rainfall. This is reflected in outgoing longwave radiation and high cloud diurnal cycle. This improvement of convective cycle has resolved a long standing problem of dry bias by CFSv2 over Indian land mass and wet bias over equatorial Indian Ocean. Besides the improvement, there are some areas where there are still scopes for further development. The cold tropospheric temperature bias, low cloud fractions need further improvement. To check the role of shallow convection, another free run is made with revised SAS along with shallow convection (SC). The major difference between the new and old SC schemes lies in the heating and cooling behavior in lower-atmospheric layers above the planetary boundary layer. However, the inclusion of revised SC scheme could not show much improvement as compared to revised SAS with deep convection. Thus, it seems that revised SAS with deep convection can be a potentially better parameterization scheme for CFSv2 in simulating ISM rainfall variability.

Ganai, Malay; Mukhopadhyay, P.; Krishna, R. Phani Murali; Mahakur, M.

2014-09-01

127

Moist Convection  

NASA Astrophysics Data System (ADS)

On Jupiter there is little doubt that the water condensation level is the seat of moist convective activity. Two major differences between Earth and Jupiter are the importance of the relatively high molecular weight of water on Jupiter and the altered bottom boundary condition on Jupiter. In addition, the triggering mechanism for convection by large scale motion is not yet understood. On Saturn the Great Storm came at a good time for Cassini observations, and the most interesting is the reversal in direction of the vertical motion tracers parahydrogen and potential temperature. Uranus and Neptune appear, on the basis of much less information, to be more exotic. With a high degree of uncertainty we here conjecture that moist convection on these planets is affected by hydrogen ortho-para latent heat in addition to water and methane and that intermittency is the outcome in both the spatial and temporal domains.

Gierasch, Peter J.

2014-11-01

128

Role of convection in redistributing formaldehyde to the upper troposphere over North America and the North Atlantic during the summer 2004 INTEX campaign  

NASA Astrophysics Data System (ADS)

Measurements of formaldehyde (CH2O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 aircraft during the summer 2004 INTEX-NA campaign to test our understanding of convection and CH2O production mechanisms in the upper troposphere (UT, 6-12 km) over continental North America and the North Atlantic Ocean. The present study utilizes these TDLAS measurements and results from a box model to (1) establish sets of conditions by which to distinguish "background" UT CH2O levels from those perturbed by convection and other causes; (2) quantify the CH2O precursor budgets for both air mass types; (3) quantify the fraction of time that the UT CH2O measurements over North America and North Atlantic are perturbed during the summer of 2004; (4) provide estimates for the fraction of time that such perturbed CH2O levels are caused by direct convection of boundary layer CH2O and/or convection of CH2O precursors; (5) assess the ability of box models to reproduce the CH2O measurements; and (6) examine CH2O and HO2 relationships in the presence of enhanced NO. Multiple tracers were used to arrive at a set of UT CH2O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. In general, production of CH2O from CH4 was found to be the dominant source term, even in perturbed air masses. This was followed by production from methyl hydroperoxide, methanol, PAN-type compounds, and ketones, in descending order of their contribution. At least 70% to 73% of the elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. In the presence of elevated NO, there was a definite trend in the CH2O measurement-model discrepancy, and this was highly correlated with HO2 measurement-model discrepancies in the UT.

Fried, Alan; Olson, Jennifer R.; Walega, James G.; Crawford, Jim H.; Chen, Gao; Weibring, Petter; Richter, Dirk; Roller, Chad; Tittel, Frank; Porter, Michael; Fuelberg, Henry; Halland, Jeremy; Bertram, Timothy H.; Cohen, Ronald C.; Pickering, Kenneth; Heikes, Brian G.; Snow, Julie A.; Shen, Haiwei; O'Sullivan, Daniel W.; Brune, William H.; Ren, Xinrong; Blake, Donald R.; Blake, Nicola; Sachse, Glen; Diskin, Glenn S.; Podolske, James; Vay, Stephanie A.; Shetter, Richard E.; Hall, Samuel R.; Anderson, Bruce E.; Thornhill, Lee; Clarke, Antony D.; McNaughton, Cameron S.; Singh, Hanwant B.; Avery, Melody A.; Huey, Gregory; Kim, Saewung; Millet, Dylan B.

2008-09-01

129

Winter Storms  

NSDL National Science Digital Library

This site offers general background about winter storms as well as interactive activities to teach visitors about these storms. It also offers a teacher's guide to using this site and links to other weather-related pages. There are four main topics: All About Winter Storms, Interactive Weather Maker, Interactive Winter Storm Timeline, and Ask Our Winter Storm Expert. All About Winter Storms gives general background information an a glossary of weather terms. The Weather Maker offers students a chance to control the weather through a simulation in which they affect the weather by changing variables such as humidity, equatorward temperature, and polarward temperature. The Storm Timeline offers students a chance to move up and down the timeline to learn about past winter storms. In Ask the Expert, students can email their questions to a winter storm expert and have them answered. This section also gives a brief biography of the expert.

1996-01-01

130

Storm Prediction Center  

NSDL National Science Digital Library

The Storm Prediction Center (SPC) is an agency of the National Oceanic and Atmospheric Administration (NOAA) National Weather Service. Materials available on the website include current weather watches, mesoscale discussions, convective outlooks, six-hour thunderstorm outlooks, and fire weather forecasts; research publications, experimental products and techniques; weather information including watch/warning maps, climatological data, and current radar; and a section on tornadoes. There is also an archive of weather images, and sections on the organization and history of the Center.

131

Orographic effects related to deep convection events over the Andes region  

NASA Astrophysics Data System (ADS)

In this work, we analyze a set of 39 storms which took place between 2006 and 2011 over the South of Mendoza, Argentina. This is a semiarid region situated at mid-latitudes (roughly between 32S and 36S) at the east of the highest Andes tops which constitutes a natural laboratory where diverse sources of gravity waves usually take place. We consider a cultivated subregion near San Rafael district, where every summer a systematic generation of deep convection events is registered. We propose that the lift mechanism required to raise a parcel to its level of free convection is partially supplied by mountain waves (MWs). From Weather Research and Forecasting (WRF) mesoscale model simulations and radar network data, we calculate the evolution of convective available potential energy and convective inhibition indices during the development of each storm. Global Final Analysis is used to construct initial and boundary conditions. Convective inhibition indices are compared with the vertical kinetic energy capable of being supplied by the MWs, in order to provide a rough estimation of this possible triggering mechanism. Vertical velocity is chosen as an appropriate dynamical variable to evidence the presence of MWs in the vicinity of each detected first radar echo. After establishing a criterion based on a previous work to represent MWs, the 39 storms are split into two subsets: with and without the presence of MWs. 12 cases with considerable MWs amplitude are retained and considered. Radar data differences between the two samples are analyzed and the simulated MWs are characterized.

Hierro, R.; Pessano, H.; Llamedo, P.; de la Torre, A.; Alexander, P.; Odiard, A.

2013-02-01

132

Deep convection observed by the Spinning Enhanced Visible and Infrared Imager on board Meteosat 8: Spatial distribution and temporal evolution over Africa in summer and winter 2006  

Microsoft Academic Search

We analyze the spatial distribution of deep convection and its diurnal cycle and life cycle over Africa in June and December 2006. We investigate regions of distinct temporal evolution and of largest frequency of occurrence of deep convection (hereinafter referred to as convective activity), and we define and identify the deep convective stage from space observations. The analysis is based

Marc Schröder; Marianne König; Johannes Schmetz

2009-01-01

133

Polarimetric and Multi-Doppler Radar Observations of Sprite-producing Storms  

NASA Technical Reports Server (NTRS)

Sprites are caused by luminous electrical breakdown of the upper atmosphere, and frequently occur over large mesoscale precipitation systems. Two sprite-producing storms (on 8 and 25 June) were observed in Colorado during the summer of 2012. Unlike most past studies of sprites, these storms were observed by a polarimetric radar - the CSU-CHILL facility - which provided both PPI and RHI scans of the cases. Also available were multiple-Doppler syntheses from CSU-CHILL, local NEXRAD radars, and the CSU-Pawnee radar; as well as data from the Colorado Lightning Mapping Array (COLMA), high speed cameras, and other lightning-detection instrumentation. This unique dataset provided an unprecedented look at the detailed kinematic and microphysical structures of the thunderstorms as they produced sprites, including electrical alignment signatures in the immediate location of the charge layers neutralized by sprite-parent positive cloud-to-ground lightning strokes. One of the sprite-producing cases (25 June) featured an anomalous charge structure and may serve as a model for how sprites can be produced over convection rather than the more typical stratiform regions. Also to be presented will be evidence for advection of charge into a common stratiform precipitation region (on 8 June), which was then tapped by lightning originating from multiple different convective cores to produce sprites. Depending on the outcome of the 2013 convective season, polarimetric data from additional storms that produce sprites and other transient luminous events (TLEs) may be presented.

Lang, TImothy J.; Lyons, Walter A.; Rutledge, Steven A.; Dolan, Brenda; Cummer, Steven A.; Krehbiel, Paul; Rison, William

2014-01-01

134

Calibration of a convective parameterization scheme in the WRF model and its impact on the simulation of East Asian summer monsoon precipitation  

NASA Astrophysics Data System (ADS)

Reasonably modeling the magnitude, south-north gradient and seasonal propagation of precipitation associated with the East Asian summer monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain-Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved. The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years. Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. By using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.

Yang, Ben; Zhang, Yaocun; Qian, Yun; Huang, Anning; Yan, Huiping

2015-03-01

135

Impact of domain size on the simulation of Indian summer monsoon in RegCM4 using mixed convection scheme and driven by HadGEM2  

NASA Astrophysics Data System (ADS)

In this study, a smaller domain over India alone and a larger South Asia (SA) domain have been used in the Regional Climate Model version 4.2 (RegCM4.2) to examine the effect of the domain size on the Indian summer monsoon simulations. These simulations were carried out over a period of 36 years at 50 km horizontal resolution with the lateral boundary forcings of the UK Met Office Hadley Centre Global Circulation Model Version 2.0. Results show that the Indian summer monsoon rainfall is significantly reduced when the domain size for the model integration is reduced from SA to the Indian domain. In case of SA domain simulation, the Equitable Threat Scores have higher values in case of very light, light and moderate rainfall events than those in case of the Indian domain simulation. It is also found that the domain size of model integration has dominant impact on the simulated convective precipitation. The cross-equatorial flow and the Somali Jet are better represented in the SA simulation than those in the Indian domain simulation. The vertically integrated moisture flux over the Arabian Sea in the SA domain simulation is close to that in the NCEP/NCAR reanalysis while it is underestimated in the Indian domain simulation. It is important to note that when RegCM4.2 is integrated over the smaller Indian domain, the effects of the Himalayas and the moisture advection from the Indian seas are not properly represented in the model simulation and hence the monsoon circulation and associated rainfall are underestimated over India.

Dash, S. K.; Pattnayak, K. C.; Panda, S. K.; Vaddi, Deepika; Mamgain, Ashu

2015-02-01

136

A long-lived mesoscale convective complex. I - The mountain-generated component  

NASA Technical Reports Server (NTRS)

The South Park Area Cumulus Experiment (SPACE) was conducted during the summer of 1977, and takes into account meteorological developments in a broad, elevated basin called South Park, which is located northeast of Colorado Springs, Colorado. The experiment was designed to investigate the organization of the mesoscale and storm-scale systems in detail over South Park. Many of the convective storms which were observed in the developing stages over South Park participated in the genesis of mesoscale convective complexes (MCCs) on the meso-alpha-scale. The present investigation is concerned with the evolution of the second MCC of this episode, which matured on the evening of August 4, 1977. Attention is given to the events from the preconvective stage early on August 4 to the incipient MCC stage in the early evening.

Cotton, W. R.; George, R. L.; Wetzel, P. J.; Mcanelly, R. L.

1983-01-01

137

Chasing Storms  

NSDL National Science Digital Library

John Monteverdi created this website to educate and entertain visitors in the science of storm chasing. Online storm journals for Spring Storm Chases from 1994 to the present take visitors through the life of a storm chaser. Throughout his discussions, the author provides weather charts and satellite images to assist visitors with the weather-related concepts. The site contains countless pictures of tornadoes and the destruction they leave behind. Although some of the amazing images take a few minutes to download, visitors will find that it is worth the wait.

Monteverdi, John

138

The Role of Convection in Redistributing Formaldehyde to the Upper Troposphere Over North America and the North Atlantic during the Summer 2004 INTEX Campaign  

NASA Technical Reports Server (NTRS)

Measurements of CH2O from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 during the summer 2004 INTEX-NA (Intercontinental Chemical Transport Experiment - North America) campaign to test our understanding of convection and production mechanisms in the upper troposphere (UT, 6-12-km) over continental North America and the North Atlantic Ocean. Point-by-point comparisons with box model calculations, when MHP (CH3OOH) measurements were available for model constraint, resulted in a median CH2O measurement/model ratio of 0.91 in the UT. Multiple tracers were used to arrive at a set of UT CH2O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. At least 66% to 73% of these elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. This distinction is important, since the effects from the former can last for over a week or more compared to one day or less in the case of convective transport of CH2O itself. In general, production of CH2O from CH4 was found to be the dominant source term, even in perturbed air masses. This was followed by production from MHP, methanol, PAN type compounds, and ketones, in descending order of their contribution. In the presence of elevated NO from lightning and potentially from the stratosphere, there was a definite trend in the CH2O discrepancy, which for the highest NO mixing ratios produced a median CH2O measurement/model ratio of 3.9 in the 10-12-km range. Discrepancies in CH2O and HO2 in the UT with NO were highly correlated and this provided further information as to the possible mechanism(s) responsible. These discrepancies with NO are consistent with additional production sources of both gases involving CH3O2 + NO reactions, most likely caused by unmeasured hydrocarbons.

Fried, Alan; Olson, Jennifer R.; Walega, Jim; Crawford, Jim H.; Chen, Gao; Weibring, Petter; Richter, Dirk; Roller, Chad; Tittel, Frank; Porter, Michael; Fuelberg, Henry; Halland, Jeremy; Bertram, Timothy H.; Cohen, Ronald C.; Pickering, Kenneth; Heikes, Brian G.

2007-01-01

139

Variability of the TRMM-PR total and convective and stratiform rain fractions over the Indian region during the summer monsoon  

NASA Astrophysics Data System (ADS)

Level 3 (3A25) TRMM Precipitation Radar (PR) data are used for 13 years period (1998-2010) to prepare climatology of TRMM PR derived near surface rain (Total rain) and rain fractions for the 4-months duration of Indian Summer Monsoon season (June-September) as well as for individual months. It is found that the total rain is contributed mostly (99 %) by two rain fractions i.e. stratiform and convective rain fractions for the season as well as on the monthly basis. It is also found that total rain estimates by PR are about 65 % of the gauge measured rain over continental India as well as on sub-regional basis. Inter-annual variability of TRMM-PR rain estimates for India mainland and its sub-regions as well as over the neighboring oceanic regions, in terms of coefficient of variability (CV) is discussed. The heaviest rain region over north Bay of Bengal (BoB) is found to have the lowest CV. Another sub-region of low CV lies over the eastern equatorial Indian ocean (EEIO). The CVs of total rain as well as its two major constituents are found to be higher on monthly basis compared to seasonal basis. Existence of a well known dipole between the EEIO and the north BoB is well recognized in PR data also. Significant variation in PR rainfall is found over continental India between excess and deficit monsoon seasons as well as between excess and deficit rainfall months of July and August. Examination of rainfall fractions between the BoB and Central India on year to year basis shows that compensation in rainfall fractions exists on monthly scale on both the regions. Also on the seasonal and monthly scales, compensation is observed in extreme monsoon seasons between the two regions. However, much less compensation is observed between the north BoB and EEIO belts in extreme rain months. This leads to speculation that the deficit and excess seasons over India may result from slight shift of the rainfall from Central India to the neighboring oceanic regions of north BoB. Contribution of stratiform and convective rain fractions have been also examined and the two fractions are found to contribute almost equally to the total rain. Results are further discussed in terms of the possible impact of the two rain fractions on circulation based on possible difference is vertical profiles of latent heat of two types of rain. Substantial differences in the lower and upper tropospheric circulation regimes are noticed in both deficit and excess monsoon months/seasons, emphasizing the interaction between rainfall (latent heat) and circulation.

Pokhrel, Samir; Sikka, D. R.

2013-07-01

140

Daytime identification of summer hailstorm cells from MSG data  

NASA Astrophysics Data System (ADS)

Identifying deep convection is of paramount importance, as it may be associated with extreme weather phenomena that have significant impact on the environment, property and populations. A new method, the hail detection tool (HDT), is described for identifying hail-bearing storms using multispectral Meteosat Second Generation (MSG) data. HDT was conceived as a two-phase method, in which the first step is the convective mask (CM) algorithm devised for detection of deep convection, and the second a hail mask algorithm (HM) for the identification of hail-bearing clouds among cumulonimbus systems detected by CM. Both CM and HM are based on logistic regression models trained with multispectral MSG data sets comprised of summer convective events in the middle Ebro Valley (Spain) between 2006 and 2010, and detected by the RGB (red-green-blue) visualization technique (CM) or C-band weather radar system of the University of León. By means of the logistic regression approach, the probability of identifying a cumulonimbus event with CM or a hail event with HM are computed by exploiting a proper selection of MSG wavelengths or their combination. A number of cloud physical properties (liquid water path, optical thickness and effective cloud drop radius) were used to physically interpret results of statistical models from a meteorological perspective, using a method based on these "ingredients". Finally, the HDT was applied to a new validation sample consisting of events during summer 2011. The overall probability of detection was 76.9 % and the false alarm ratio 16.7 %.

Merino, A.; López, L.; Sánchez, J. L.; García-Ortega, E.; Cattani, E.; Levizzani, V.

2014-04-01

141

High-Resolution Modeling of the Predictability of Convective Systems, and Influences by Absorbing Aerosols Over Northern India and the Himalayas Foothills During Boreal Summer  

NASA Technical Reports Server (NTRS)

The Himalayas foothills region (HFR) is an important component of the South Asian monsoon. To the south, the HFR borders the fertile, populous, and heavily polluted Indo-Gangetic Plain (IGP). To the north, it rises to great height (approx. 4-5 km) to the Tibetan Plateau over a distance of less than 100 km. The HFR itself consists of complex mountainous terrain, with strong orographic forcing for precipitation. During the late spring and early summer, dust aerosol from the Thar and Middle East deserts , as well as moisture from the Arabian Sea were transported to the western part of the western part of the IGP and foothills spurs pre-monsoon severe thunderstorm over the region. During the monsoon season (mid June -August) convection from the Bay of Bengal, spread along the foothills northwestward to northern Pakistan. Recent climate model studies and preliminary observations have indicted not only the importance of dynamical forcing of precipitation in the HFR, but also possible strong impacts by the dense aerosols, from both local sources, and remote transport, that blanket the IGP from late spring up to the onset of the monsoon in June, and during monsoon breaks in July. In this work, we use the NASA Unified Weather Research and Forecasting (Nu-WRF) model to study the predictability ( 1-7 days) South Asian monsoon rainfall system. Results of 7 -day forecast experiments using an embedded domain of 27 km and 9 km resolution were conducted for the period June 11- July 15, 2008, with and without aerosol forcing are carried out to assess the intrinsic predictability of rainfall over the HFR, and possible impacts by aerosol direct effect, and possible connection of large-scale South Asian monsoon system.

Kim, Kyu-Myong; Lau, William K.-M.; Tao, Wei-Kuo; Shi, Jainn; Tan, Qian; Chin, Mian; Matsui, Toshihisa; Bian, Huisheng

2011-01-01

142

Dust Storm  

Atmospheric Science Data Center

article title:  Massive Dust Storm over Australia     View Larger Image ... and dry conditions caused a massive blanket of dust from Australia's Outback to spread eastward across Queensland and New South Wales. ...

2013-04-16

143

EXTRATROPICAL SYNOPTIC-SCALE PROCESSES AND SEVERE CONVECTION  

E-print Network

EXTRATROPICAL SYNOPTIC-SCALE PROCESSES AND SEVERE CONVECTION Chapter 2 in Severe Convective Storms perspective of the interaction between severe convection and extratropical synoptic-scale processes severe convection develops (see, e.g., Newton 1963; Barnes and Newton 1983; Johns and Doswell 1992

Doswell III, Charles A.

144

Magnetic Storms  

NSDL National Science Digital Library

This is a lesson to introduce the Kp index, a common numerical indicator of magnetic storminess. Learners will access and analyze Kp index plots of magnetic storm strength and determine the relative frequency of stronger versus weaker magnetic storms during years of maximum solar activity. This resource is activity 13 from the Magnetic Mysteries of the Aurora teachers guide. Internet access is required for this activity.

2012-08-03

145

Infrasound generation by tornadic supercell storms  

E-print Network

Acoustic wave generation by turbulence in the stratified, moist atmosphere is studied. It is shown that in the saturated moist air turbulence in addition to the Lighthill's quadrupole and the dipole sources of sound related to stratification and temperature fluctuations, there exist monopole sources related to heat and mass production during the condensation of moisture. We determine acoustic power of these monopole sources. Performed analysis shows that the monopole radiation is dominant for typical parameters of strong convective storms. Obtained results are in good qualitative agreement with the main observed characteristics of infrasound radiation by strong convective storms such as total acoustic power and characteristic frequency.

Akhalkatsi, M

2008-01-01

146

Convective cell development and propagation in a mesoscale convective complex  

E-print Network

echoes at 1200 GMT- ? ? - 49 INTRODUCTION For many years, meteorologists had believed that thunderstorms occurred in two basic forms: air mass storms represented by isolated cells and squall lines involving many cells organized into a line. However... third mode of thunderstorm activity has been recently discovered. It has been found that many summertime storms are organized aggregations of thunderstorm cells which Maddox (1980b) has called mesoscale convective complexes (MCCs). The "supercell...

Ahn, Yoo-Shin

1987-01-01

147

Monitoring and Understanding Trends in Extreme Storms: State of Knowledge  

E-print Network

The state of knowledge regarding trends and an understanding of their causes is presented for a specific subset of extreme weather and climate types. For severe convective storms (tornadoes, hailstorms, and severe ...

Kunkel, Kenneth E.

148

Radar studies of heavy convective rainfall in mountainous terrain  

NASA Astrophysics Data System (ADS)

Heavy rainfall, topography, storm motion, and storm evolution are closely linked for four storms that produced catastrophic flooding along the Front Range of the Rocky Mountains and the east slope of the Blue Ridge Mountains. Storms selected for detailed study in this paper are the Rapidan storm of June 27, 1995, the Fort Collins storm of July 28, 1997, the Buffalo Creek storm of July 12, 1996, and the Monocacy storm of June 18, 1996. The Buffalo Creek storm and the Fort Collins storm occurred in the Front Range of the Rocky Mountains in Colorado; the Rapidan and Monocacy storms occurred along the east slopes of the Blue Ridge of Virginia and southern Pennsylvania. The four storms caused catastrophic flooding at drainage basin scales between 1 and 1000 km2. The scale of flood response for these events imposes a need to characterize rainfall variability at very fine space scales and timescales, of the order of 1 km spatial scale and 1-5 min timescale. A fundamental issue for the hydrometeorology of extreme rainfall in mountainous terrain is whether anomalously large rainfall accumulations in orographic convection result from anomalously slow net storm motion, anomalously large rainfall rates, or both. Anomalous storm motion and processes resulting in catastrophic rainfall rates are examined for each of the four storms. Of particular importance for anomalous storm motion in orographic convection are interactions between the low-level wind field and terrain features.

Landel, Gregoire; Smith, James A.; Baeck, Mary Lynn; Steiner, Matthias; Ogden, Fred L.

1999-01-01

149

Tropical Storm Erin  

NASA Technical Reports Server (NTRS)

Location: The Atlantic Ocean 210 miles south of Galveston, Texas Categorization: Tropical Storm Sustained Winds: 40 mph (60 km/hr)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Infrared ImageMicrowave Image

Infrared Images Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

Microwave Images In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue. Therefore deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. Land appears much warmer due to its high radiation emissivity.

Visible/Near-Infrared Images The AIRS instrument suite contains a sensor that captures radiation in four bands of the visible/near-infrared portion of the electromagetic spectrum. Data from three of these bands are combined to create 'visible' images similar to a snapshot taken with your camera.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

2007-01-01

150

Dust Storm  

Atmospheric Science Data Center

article title:  Elevated Dust over the Middle East     View ... on April 11, 2004 (top panels) contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom ... (MISR) depict both the abundance of airborne dust, and its height above the surface. The natural-color views at left ...

2013-04-16

151

Weak linkage between the heaviest rainfall and tallest storms  

PubMed Central

Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. PMID:25708295

Hamada, Atsushi; Takayabu, Yukari N.; Liu, Chuntao; Zipser, Edward J.

2015-01-01

152

Weak linkage between the heaviest rainfall and tallest storms  

NASA Astrophysics Data System (ADS)

Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection.

Hamada, Atsushi; Takayabu, Yukari N.; Liu, Chuntao; Zipser, Edward J.

2015-02-01

153

Characteristics of ionospheric storms in East Asia  

NASA Astrophysics Data System (ADS)

???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.

Wang, Xiao; Wang, Guojun; Shi, Jiankui

154

Storm morphology and electrification from CHUVA-GLM Vale do Paraiba field campaign  

NASA Astrophysics Data System (ADS)

CHUVA [Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)] Project is a series of itinerant field campaigns with the objective of characterizing the main precipitating systems observed in Brazil as a support for Global Precipitation Measurement (GPM) mission. The fourth field campaign was conducted at Vale do Paraiba in São Paulo, Brazil, from 1 November 2011 to 31 March 2012. For this specific field experiment, several lightning location systems (LLS) were deployed as part of GOES-R Geostationary Lightning Mapper (GLM) and MTG Lightning Imager (LI) pre-launch activities, resulting in a joint effort between INPE, USP, NOAA, NASA, EUMETSAT and several vendors of operational LLS for network intercomparison and GLM and LI proxy data generation. Among these networks, 4 of them detect total (intra-cloud and cloud-to-ground) lightning, including a Lightning Mapping Array (LMA), allowing a detailed description of the cloud electrification. To depict precipitating weather systems, CHUVA uses a mobile XPOL Doppler Radar, micro-rain radars, disdrometers, rain gauges, microwave radiometer, Lidar, and a GPS network for water vapor retrievals. Also, Vale do Paraíba and São Paulo are covered by 3 operational S-band radars. The precipitation data collected by these radars and the lightning detected by the LLS were grouped in a structure of storm features built by tracking the precipitating systems and its associated lightning. This storm feature database makes it easier to group similar convective systems and compare them in terms of area, lifetime, rainfall and convection intensity, lightning activity, and more. During this field experiment a large variety of cloud systems were sampled: cold fronts, squall lines, the South Atlantic Convergence Zone (SACZ) and local convective systems. Microphysical characteristics (such as hydrometeor identification and ice/water mass) of these summer 2011-2012 precipitating systems can be inferred from the X-Pol and 3 operational S-band radars, and the LLS provide detailed information about the storms electrical activity (such as charge centers and lighting propagation processes). We will summarize the results from this experiment providing an in-depth study of the relationship between the storm type and its microphysical-electrical characteristics by presenting the role of storm morphology on cloud electrification, rainfall and severe weather (hail and damaging winds) production. Also, this storm feature database will provide an easy access to CHUVA data for case studies and GLM and LI activities.

Albrecht, R. I.; Morales, C.; Lima, W. F.; Biscaro, T. S.; Mello, I. B.

2013-12-01

155

Metal Storm  

NSDL National Science Digital Library

The National Institute of Justice (NIJ) is exploring a unique application of biometrics technologies: a handgun that can recognize its owner and only fire when being held by that person. This innovation could make it impossible for a criminal to steal an officer's firearm and use it against other people. Metal Storm, the company that is working with the NIJ to develop the gun, has presentations and technology descriptions on its home page.

156

Severe dust storms over the Arabian Peninsula: Observations and modeling  

NASA Astrophysics Data System (ADS)

Dust aerosols and dust storms have tremendous effects on human health and all development activities. Also atmospheric dust plays a major role in the Earth climate system by its interaction with radiation and clouds. Severe dust storms are considered the severest phenomena in the Arabian Peninsula, since they are occurring all the year round with maximum activity and frequency in Summer. The Regional Climate Model (RegCM4) has been used to simulate severe dust storms events in the Arabian Peninsula from 1998 up to 2011. This long period simulation shows a typical pattern and dynamical features of the large-scale severe dust storm in winter seasons and summer seasons. The Aerosol Optical Depth (AOD) from the model outputs have been compared against ground--base observations of three AERONET stations (i.e., Kuwait, Mazeria and Solar-Village) and daily space--based observations of MISR, Deepblue and OMI. The dynamical analysis of the large—scale severe dust storms reveal the difference between winter time storms and summer time storm. Winter time storm occurs when the cold air front in the north is coupled with the extension of the Red Sea trough from the south. However, the summer time storm is associated with strong Shamal wind that extend from northern Kuwait to the southern Arabian Peninsula.

shalaby, ahmed

2014-05-01

157

Modeling "dusk-effect" during the main phase of geomagnetic storm  

NASA Astrophysics Data System (ADS)

Among the positive ionospheric disturbances which have appeared at the mid-or high latitudes during the main phase of magnetic storm, the evening electron density enhancements attract considerable interest. Usually those enhancements known as the "dusk" effect were observed in the subauroral and auroral ionosphere. Therefore it was suggested that moving auroral oval towards equator during the main phase of magnetic storm is the reason of "dusk" effect. The following observations by incoherent radar system at Millstone-Hill (American longitudinal sec-tor) made it possible to describe in details variations of the main characteristics of this event. At present it is established that "dusk" effect is significantly observed in summer and occurs more frequently in the course of the high geomagnetic activity periods. From the point of view of modern aeronomy the formation of abnormal electron density enhancements in evening ionosphere may be due to action of three principal factors: (i) magnetospheric convection and energetic electron precipitations; (ii) lifting of the F2-layer under the action of enhanced ther-mospheric wind, blowing towards equator and electromagnetic drift; (iii) propagation towards low latitudes of large scaled thermospheric waves, resulting in quick changes of thermospheric composition. The numerical model of ionosphere and plasmasphere was used, in which the vari-ations of the convection velocity, electron precipitation and thermospheric wind corresponded to the storm scenario. It was established following: -"dusk effect" takes place at the mid-and subauroral latitudes of the American longitudinal sector whereas it is at the subauroral latitudes of the Asia longitudinal sector; -the magnetospheric convection and energetic electron precipitations are considerable importance in the formation of "dusk effect" at the subauroral latitudes of the both American and Asia sectors; -thermospheric wind is responsible for the "dusk effect" at the midlatitudes of the American sector and it doesn't manifest itself in the Asia longitudinal sector.

Tashchilin, Anatoly; Romanova, Elena

158

Evaluation of UAS Concepts of Operation for Severe Storm Penetration using Hardware-in-the-Loop  

E-print Network

Evaluation of UAS Concepts of Operation for Severe Storm Penetration using Hardware-in-the-loop simulation of unmanned aircraft flight through severe storms is described. The system combines a full six severe convective storms. Interfaces have been written to enable the use of system hardware where

Frew, Eric W.

159

Viewing a California Storm  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] AIRS infrared channel 1486AIRS infrared channel 2616 [figure removed for brevity, see original site] Scale [figure removed for brevity, see original site] [figure removed for brevity, see original site] AMSU-A microwave channel 2 AMSU-A microwave channel 15

Looking as if they were tie-dyed, the images shown above of a recent California storm have meaning in their color. With cooler areas pushing to purple and warmer areas pushing to red, the images are a snapshot of a storm moving up from the lower latitudes.

The Vis/NIR image reveals three distinct very large 'blooms' within the large cloud formation, which may be major convective cells. The images show a prominent squall line pointing nearly north-south that is approaching the coast, and a large isolated cloud formation almost due west. Both features have high cold cloud tops, according to the AIRS image, and both were probably a major source of intense rainfall. The AMSU-A microwave sensor reveals the warm land surface and the moisture below the cloud tops.

2003-01-01

160

OPEN-OCEAN CONVECTION: OBSERVATIONS, THEORY, AND MODELS  

E-print Network

OPEN-OCEAN CONVECTION: OBSERVATIONS, THEORY, AND MODELS John Marshall Department of Earth by intermittent, deep-reaching convection, triggered by winter storms. Observational, laboratory, and modeling studies reveal a fascinating and complex interplay of convective and geostrophic scales, the large

Marshall, John

161

Principles of Convection II: Using Hodographs  

NSDL National Science Digital Library

This module provides a basic understanding of how to plot and interpret hodographs, with application to convective environments. Most of the material previously appeared in the CD module, Anticipating Convective Storm Structure and Evolution, developed with Dr. Morris Weisman. Principles of Convection II: Using Hodographs includes a concise summary for quick reference and a final exam to test your knowledge. The module comes with audio narration, rich graphics, and a companion print version.

2014-09-14

162

POCATELLO STORM DRAIN STUDY, BANNOCK COUNTY, IDAHO - 1979  

EPA Science Inventory

The City of Pocatello (17040208) storm drains were sampled during a winter snowmelt period and during a summer rainstorm. Chemical analyses of the drain water indicated levels of suspended solids, total solids, Chemical Oxygen Demand, sodium, potassium, chloride, fluoride, arsen...

163

Day-time identification of summer hailstorm cells from MSG data  

NASA Astrophysics Data System (ADS)

Identifying deep convection is of paramount importance, as it may be associated with extreme weather that has significant impact on the environment, property and the population. A new method, the Hail Detection Tool (HDT), is described for identifying hail-bearing storms using multi-spectral Meteosat Second Generation (MSG) data. HDT was conceived as a two-phase method, in which the first step is the Convective Mask (CM) algorithm devised for detection of deep convection, and the second a Hail Detection algorithm (HD) for the identification of hail-bearing clouds among cumulonimbus systems detected by CM. Both CM and HD are based on logistic regression models trained with multi-spectral MSG data-sets comprised of summer convective events in the middle Ebro Valley between 2006-2010, and detected by the RGB visualization technique (CM) or C-band weather radar system of the University of León. By means of the logistic regression approach, the probability of identifying a cumulonimbus event with CM or a hail event with HD are computed by exploiting a proper selection of MSG wavelengths or their combination. A number of cloud physical properties (liquid water path, optical thickness and effective cloud drop radius) were used to physically interpret results of statistical models from a meteorological perspective, using a method based on these "ingredients." Finally, the HDT was applied to a new validation sample consisting of events during summer 2011. The overall Probability of Detection (POD) was 76.9% and False Alarm Ratio 16.7%.

Merino, A.; López, L.; Sánchez, J. L.; García-Ortega, E.; Cattani, E.; Levizzani, V.

2013-10-01

164

Generation Mechanisms of Convectively Forced Internal Gravity Waves and Their Propagation to the Stratosphere  

Microsoft Academic Search

Characteristics of gravity waves induced by mesoscale convective storms and the gravity wave sources are investigated using a two-dimensional cloud-resolving numerical model. In a nonlinear moist (control) simulation, the convective system reaches a quasi-steady state after 4 h in which convective cells are periodically regenerated from a gust front updraft. In the convective storms, there are two types of wave

In-Sun Song; Hye-Yeong Chun

2003-01-01

165

STORM TIDE SIMULATIONS FOR HURRICANE HUGO (1989): ON THE SIGNIFICANCE OF INCLUDING INLAND FLOODING AREAS  

E-print Network

STORM TIDE SIMULATIONS FOR HURRICANE HUGO (1989): ON THE SIGNIFICANCE OF INCLUDING INLAND FLOODING Florida Orlando, Florida Summer Term 2004 #12;ABSTRACT In this study, storm tides are simulated element models with triangular elements are applied in order to simulate the storm tides, allow

Central Florida, University of

166

Storm Track Dynamics  

Microsoft Academic Search

This paper reviews the current state of observational, theoretical, and modeling knowledge of the midlatitude storm tracks of the Northern Hemisphere cool season.Observed storm track structures and variations form the first part of the review. The climatological storm track structure is described, and the seasonal, interannual, and interdecadal storm track variations are discussed. In particular, the observation that the Pacific

Edmund K. M. Chang; Sukyoung Lee; Kyle L. Swanson

2002-01-01

167

Ongoing Studies of the Characteristics of Storms and Lightning Discharges Which Do and Do Not Produce Sprites  

NASA Astrophysics Data System (ADS)

Within a year after the first intentional ground and aircraft monitoring of sprites (1993), it had become apparent that this class of mesospheric transient luminous event was almost uniquely associated with positive polarity cloud-to-ground lightning strokes (+CGs). Yet not all +CGs, even those with high peak currents, produce sprites. Moreover, sprite parent +CGs (SP+CGs) tend to occur only in certain types of convective storm systems. On the U.S. High Plains, the SP+CGs are most common in the stratiform precipitation regions of mature mesoscale convective systems (MCSs) larger than 10-20x10**4 km**2. The summer 2000 Severe Thunderstorm Electrification and Precipitation Study (STEPS) produced the most complete database of coordinated low-light television (LLTV), 3-D lightning mapping array (LMA) and remote ELF transient data available to date. A major question is whether large charge moment changes are both a necessary and a sufficient condition for sprites? This presentation presents the results of a reanalysis of the STEPS database which, aided by ELF charge moment change estimates, has revealed substantially more events than in the original catalog. Particular attention is paid to charge moment changes in three major classes of storms, (1) MCSs with many SP+CGs in the stratiform region, (2) supercells with only sporadic sprite events during restricted portions of their life cycle, and (3) MCSs and supercell storms which, in spite of many +CGs, produce no transient luminous events. In addition, the characteristics of continuing currents in High Plains lightning discharges monitored using high speed video cameras (1000 fps) is compared with ELF/ULF measurements (Courtesy: Martin Fullekrug). Additional observations of sprites and elves were obtained during summer 2003, in conjunction with an upgraded Duke University ELF transient monitoring system. Some initial results will be presented.

Lyons, W. A.; Cummer, S. A.; Stanley, M. A.

2003-12-01

168

Research Opportunities at Storm Peak Laboratory  

NASA Astrophysics Data System (ADS)

The Desert Research Institute (DRI) operates a high elevation facility, Storm Peak Laboratory (SPL), located on the west summit of Mt. Werner in the Park Range near Steamboat Springs, Colorado at an elevation of 3210 m MSL (Borys and Wetzel, 1997). SPL provides an ideal location for long-term research on the interactions of atmospheric aerosol and gas- phase chemistry with cloud and natural radiation environments. The ridge-top location produces almost daily transition from free tropospheric to boundary layer air which occurs near midday in both summer and winter seasons. Long-term observations at SPL document the role of orographically induced mixing and convection on vertical pollutant transport and dispersion. During winter, SPL is above cloud base 25% of the time, providing a unique capability for studying aerosol-cloud interactions (Borys and Wetzel, 1997). A comprehensive set of continuous aerosol measurements was initiated at SPL in 2002. SPL includes an office-type laboratory room for computer and instrumentation setup with outside air ports and cable access to the roof deck, a cold room for precipitation and cloud rime ice sample handling and ice crystal microphotography, a 150 m2 roof deck area for outside sampling equipment, a full kitchen and two bunk rooms with sleeping space for nine persons. The laboratory is currently well equipped for aerosol and cloud measurements. Particles are sampled from an insulated, 15 cm diameter manifold within approximately 1 m of its horizontal entry point through an outside wall. The 4 m high vertical section outside the building is capped with an inverted can to exclude large particles.

Hallar, A. G.; McCubbin, I. B.

2006-12-01

169

The impact of land cover change on storms in the Sydney Basin, Australia  

NASA Astrophysics Data System (ADS)

This study has used a numerical model (RAMS) at 1 km horizontal grid intervals over the Sydney Basin to assess the impact of land cover change on storms. Multiple storms using the National Center for Environmental Prediction (NCEP) reanalysis data were simulated with pre-European settlement land cover then re-simulated with land cover representing Sydney's current land use pattern. While all simulated storms did not respond to the change in land cover consistently, storms of similar types responded in comparable ways. All simulated synoptically forced storms (e.g. those triggered by cold fronts) were unresponsive to a changed land surface, while local convective storms were highly sensitive to the triggering mechanism associated with land surface influences. Storms travelling over the smoother agricultural land in the south-west of the Sydney Basin experienced an increase in velocity, and in a special case, the dense urban surface of Sydney's city core appears to trigger an intense convective storm. It is shown that the dynamical setting predominantly triggers storm outbreaks. This is seen most clearly in the isolated convective storm category where the sea breeze front often dictates the location of storm cell initiation.

Gero, A. F.; Pitman, A. J.; Narisma, G. T.; Jacobson, C.; Pielke, R. A.

2006-11-01

170

Evaluation of the model representation of the evolution of convective systems using satellite observations of outgoing  

E-print Network

Evaluation of the model representation of the evolution of convective systems using satellite October 2010. [1] We introduce a technique for assessing the diurnal development of convective storm systems based on outgoing longwave radiation fields. Using the size distribution of the storms measured

Hogan, Robin

171

Flow over Heated Terrain. Part II: Generation of Convective Precipitation  

E-print Network

indicate that precipitating convection was more likely to be generated downwind of ridges than upwind of them. Initiation of these storms was more likely downwind of ridges with their long axis parallel to the wind direction than downwind of ridges...

Tucker, Donna F.; Crook, N. Andrew

2005-09-01

172

Spectrum of infrasound radiation from supercell storms  

E-print Network

We consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high values of convective available potential energy (CAPE), which are known to favor significant tornadoes, also lead to a strong enhancement of supercell's low frequency acoustic radiation.

Akhalkatsi, Mariam

2010-01-01

173

Limits to Flood Forecasting in the Colorado Front Range for Two Summer Convection Periods Using Radar Nowcasting and a Distributed Hydrologic Model  

Microsoft Academic Search

Flood forecasting in mountain basins remains a challenge given the\\u000a difficulty in accurately predicting rainfall and in representing\\u000a hydrologic processes in complex terrain. This study identifies flood\\u000a predictability patterns in mountain areas using quantitative\\u000a precipitation forecasts for two summer events from radar nowcasting and\\u000a a distributed hydrologic model. The authors focus on 11 mountain\\u000a watersheds in the Colorado Front Range

Hernan A. Moreno; Enrique R. Vivoni; David J. Gochis

2013-01-01

174

Nowcasting, warning, mitigation, and documentation of hail storms in Styria, Austria  

NASA Astrophysics Data System (ADS)

The South-East of the Austrian province of Styria is a hail-hotspot. Typically on more than 50 days in summer hail warnings are released. Since decades, hail mitigation actions are carried out by means of specially equipped aircraft seeding 'suspicious' clouds with silver-iodide generators. In the year 2009, a project was started with the goal to document hail events and to increase the efficiency of hail finding measures. Since decades, the weather situation is observed in this region by the Austrian C-band weather radar network that provides every five minutes updated 3D reflectivity and velocity measurements with a resolution of 1 km. In 2009, the aircraft used for cloud seeding have been equipped with GPS sensors and tablet PCs. As a consequence, the position of the aircraft is accessible in close to real time and can be marked in the weather radar images. Further, the aircraft pilots have access to the current weather radar images. This idea guarantees a two-way information exchange. On the one hand, the pilots get a full picture of the overall weather situation. On the other hand, it can be documented what cloud cells the experienced aircraft pilots regarded as critical and when and where they chose to seed. Since the project started, aircraft seeding has been documented on more than 150 days. This study analyzes convective storms as they were tracked with the weather radar during their life cycle - from the origin to the collapse. Both categories of cells, seeded and unseeded ones, have been analyzed. The duration, the path-length of the track over ground, the vertical profile, the zero-degree isotherm, as well as the precipitation rate have been extracted. These datasets will allow the evaluation of forecast models for convective storms. It was further evaluated if the seeded convective storms met standardized seeding criteria. A long term perspective of the ongoing project is a scientific analysis of the effects of the hail suppression measures based on the comparison of seeded and unseeded convective cells and on documented hail information from the ground.

Teschl, Franz; Teschl, Reinhard; Paulitsch, Helmut; Randeu, Walter L.

2013-04-01

175

Mantle Convection  

NSDL National Science Digital Library

This page discusses thermal convection as it applies to the Earth's mantle and includes three QuickTime movies for three different cases of convection: heating from below, heating from within, and a combination of the two.

H. Schmeling

176

Exploring Hurricane Storm Surge  

NSDL National Science Digital Library

Hurricanes cause damage in three ways: wind, rain, and storm surge. This project explores the causes and effects of storm surge in hurricanes. While wind and rain are two of the most obvious effects of hurricanes, storm surge can be one of the most destructive. This project involves using the resources from the NSDL to understand why storm surge occurs, where it occurs, and what governs how bad it can be. Start by reading ...

Dean

2006-05-15

177

STORM WATER Residential  

E-print Network

STORM WATER QUALITY HOTLINE UCSC Residential Car Washing http THAT MAY CAUSE ENVIRONMENTAL HARM TO THE STORM WATER QUALITY HOTLINE: (831) 459-2553. LIKE US ON FACEBOOK AT UCSC STORM WATER MANAGEMENT PROGRAM! DID YOU KNOW? PRACTICAL SOLUTIONS > USE A COMMERCIAL CAR WASH

California at Santa Cruz, University of

178

Infrasound generation by turbulent convection  

E-print Network

Low frequency acoustic wave generation is studied taking into account the effect of stratification, inhomogeneity of background velocity profile and temperature fluctuations. It is shown that for the typical parameters of convective storms the dipole radiation related to temperature inhomogeneities is at least of the same order as radiation of Lighthill's quadrupole source. It is also shown that the source related to stratification could have valuable contribution whereas some other sources are shown to be inefficient.

Akhalkatsi, M; Morrison, P J

2004-01-01

179

Infrasound generation by turbulent convection  

E-print Network

Low frequency acoustic wave generation is studied taking into account the effect of stratification, inhomogeneity of background velocity profile and temperature fluctuations. It is shown that for the typical parameters of convective storms the dipole radiation related to temperature inhomogeneities is at least of the same order as radiation of Lighthill's quadrupole source. It is also shown that the source related to stratification could have valuable contribution whereas some other sources are shown to be inefficient.

M. Akhalkatsi; G. Gogoberidze; P. J. Morrison

2004-09-15

180

Test and evaluation plan for the Centralized Storm Information System  

NASA Technical Reports Server (NTRS)

The installation of the Centralized Storm Information System (CSIS) at the NOAA operational complex in Kansas City, Missouri is described. This complex includes the National Severe Storms Forecast center and a Satellite Field Service Station which is denoted in this research plan as NSSFC. CSIS computers will act in concert to merge analyze the many data sets needed to forecast severe convective storms. Specific aspects of CSIS are evaluated against the CSIS objectives. The functions to be evaluated characterize the attributes of a generalized interactive computer system. A major development in the CSIS program will allow communication between CSIS and the NSSFC Eclipse computer.

1985-01-01

181

Interannual variability of planet-encircling dust storms on Mars  

NASA Technical Reports Server (NTRS)

A recent review of earth-based telescopic observations of Mars together with Viking orbiter and lander data are employed to estimate the frequency of occurrence of planet-encircling dust storms over the past century and to test whether the period spanned by the Mariner 9 and Viking missions to Mars is representative of the decades prior to 1950. Both spacecraft and earth-based observations suggest that planet-encircling dust storms on Mars occur during a 'dust storm season' in southern spring and summer. Viking data show that planet-encircling dust storms could have occurred in the past on Mars without being detected from earth during years in which Mars was far from earth during the dust storm season. Planet-encircling storms were absent during the dust storm seasons monitored during several favorable oppositions prior to 1956 and after 1986. The change of a planet-encircling dust storm occurring in any arbitrary Mars year is estimated to be approximately one in three, if this occurrence is random from year to year and yet restricted seasonally to southern spring and summer.

Zurek, Richard W.; Martin, Leonard J.

1993-01-01

182

Storms in Space  

NASA Astrophysics Data System (ADS)

Introduction; The cast of characters; Vignettes of the storm; 1. Two kinds of weather; 2. The saga of the storm; 3. Weather stations in space; 4. Lights in the night: the signature of the storm; 5. A walking tour of the magnetosphere; 6. The sun: where it all begins; 7. Nowcasting and forecasting storms in space; 8. Technology and the risks from storms in space; 9. A conversation with Joe Allen; 10. Manned exploration and space weather hazards; 11. The present and future of space weather forecasting; Mathematical appendix. A closer look; Glossary; Figure captions.

Freeman, John W.

2012-11-01

183

Application of new methods based on ECMWF ensemble model for predicting severe convective weather situations  

NASA Astrophysics Data System (ADS)

The short and medium range operational forecasts, warning and alarm of the severe weather are one of the most important activities of the Hungarian Meteorological Service. Our study provides comprehensive summary of newly developed methods based on ECMWF ensemble forecasts to assist successful prediction of the convective weather situations. . In the first part of the study a brief overview is given about the components of atmospheric convection, which are the atmospheric lifting force, convergence and vertical wind shear. The atmospheric instability is often used to characterize the so-called instability index; one of the most popular and often used indexes is the convective available potential energy. Heavy convective events, like intensive storms, supercells and tornadoes are needed the vertical instability, adequate moisture and vertical wind shear. As a first step statistical studies of these three parameters are based on nine years time series of 51-member ensemble forecasting model based on convective summer time period, various statistical analyses were performed. Relationship of the rate of the convective and total precipitation and above three parameters was studied by different statistical methods. Four new visualization methods were applied for supporting successful forecasts of severe weathers. Two of the four visualization methods the ensemble meteogram and the ensemble vertical profiles had been available at the beginning of our work. Both methods show probability of the meteorological parameters for the selected location. Additionally two new methods have been developed. First method provides probability map of the event exceeding predefined values, so the incident of the spatial uncertainty is well-defined. The convective weather events are characterized by the incident of space often rhapsodic occurs rather have expected the event area can be selected so that the ensemble forecasts give very good support. Another new visualization tool shows time evolution of predefined multiple thresholds in graphical form for any selected location. With applying this tool degree of the dangerous weather conditions can be well estimated. Besides intensive convective periods are clearly marked during the forecasting period. Developments were done by MAGICS++ software under UNIX operating system. The third part of the study usefulness of these tools is demonstrated in three interesting cases studies of last summer.

Lazar, Dora; Ihasz, Istvan

2013-04-01

184

The relative contributions of summer and cool-season precipitation to groundwater recharge, Spring Mountains, Nevada, USA  

USGS Publications Warehouse

A comparison of the stable-isotope signatures of spring waters, snow, snowmelt, summer (July thru September) rain, and cool season (October thru June) rain indicates that the high-intensity, short-duration summer convective storms, which contribute approximately a third of the annual precipitation to the Spring Mountains, provide only a small fraction (perhaps 10%) of the recharge to this major upland in southern Nevada, USA. Late spring snowmelt is the principal means of recharging the fractured Paleozoicage carbonate rocks comprising the central and highest portion of the Spring Mountains. Daily discharge measurements at Peak Spring Canyon Creek during the period 1978-94 show that snowpacks were greatly enhanced during E1 Nin??o events.

Winograd, I.J.; Riggs, A.C.; Coplen, T.B.

1998-01-01

185

Vorticity imbalance and stability in relation to convection  

NASA Technical Reports Server (NTRS)

A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

Read, W. L.; Scoggins, J. R.

1977-01-01

186

Extreme convection of the near-equatorial Americas, Africa, and adjoining oceans as seen by TRMM  

E-print Network

1 Extreme convection of the near-equatorial Americas, Africa, and adjoining oceans as seen by TRMM;2 Abstract This study documents the preferred location and diurnal cycle of extreme convective storms Ocean, and Northern Africa. Data from the TRMM Precipitation Radar show three types of convective

Houze Jr., Robert A.

187

Tropical Storm Ernesto over Cuba  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Microwave Image

These infrared, microwave, and visible images were created with data retrieved by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite.

Infrared Image Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

Microwave Image In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue. Therefore deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. Land appears much warmer due to its high radiation emissivity.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

2006-01-01

188

Modeling Convection  

NSDL National Science Digital Library

Typically, teachers use simple models that employ differences in temperature and density to help students visualize convection. However, most of these models are incomplete or merely hint at (instead of model) convective circulation. In order to make the use of models more effective, the authors developed an alternative system that uses a simple, low-cost apparatus that not only maintains dynamic convective circulation, but also illustrates two adjacent cells that teaches students about Earth's processes.

Amanda Schulz

2004-09-01

189

Storm Alert: Latest Updates on Campus Closures ***STORM ALERT***  

E-print Network

Storm Alert: Latest Updates on Campus Closures 1 message ***STORM ALERT*** TROPICAL STORM ISAAC and another Storm Alert will be issued at 8 p.m. People should not return to campus until the all-clear has 26, 2012 9:53:18 AM Subject: Storm Alert: Latest Updates on Campus Closures #12;· Refrain from using

Miami, University of

190

Large Eddy Simulations of Severe Convection Induced Turbulence  

NASA Technical Reports Server (NTRS)

Convective storms can pose a serious risk to aviation operations since they are often accompanied by turbulence, heavy rain, hail, icing, lightning, strong winds, and poor visibility. They can cause major delays in air traffic due to the re-routing of flights, and by disrupting operations at the airports in the vicinity of the storm system. In this study, the Terminal Area Simulation System is used to simulate five different convective events ranging from a mesoscale convective complex to isolated storms. The occurrence of convection induced turbulence is analyzed from these simulations. The validation of model results with the radar data and other observations is reported and an aircraft-centric turbulence hazard metric calculated for each case is discussed. The turbulence analysis showed that large pockets of significant turbulence hazard can be found in regions of low radar reflectivity. Moderate and severe turbulence was often found in building cumulus turrets and overshooting tops.

Ahmad, Nash'at; Proctor, Fred

2011-01-01

191

Characterizing Extreme Ionospheric Storms  

NASA Astrophysics Data System (ADS)

Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for measuring ionospheric storm magnitudes. Since the level of ionospheric disturbance (as represented, for example, by enhancements or depletions in total electron content) does not always scale directly with the level of geophysical disturbance in a coincident magnetic storm, however, an independent, purely ionospheric storm index is preferable for ranking ionospheric storms by their magnitudes. Our storm magnitude metric is calculated from the standard ?2 goodness-of-fit parameter values associated with estimates of vertical total electron content (derived from observations collected by networks of GPS receivers) on a grid at regularly spaced intervals of geodetic latitude and longitude. It takes into account both the instantaneous magnitude of the storm and its temporal duration.

Sparks, L.; Komjathy, A.; Altshuler, E.

2011-12-01

192

The development of convective instability in relation to convective activity and synoptic systems in AVE IV  

E-print Network

Administration's fourth Atmospheric Variability Experiment (AVE IV). The 3- and 6-h sounding intervals allowed time changes in convective stability to be studied in areas of convective storms. A stability development equation was derived and each term... was examined to determine when and where it made a significant contribution to the development process. The usefulness of satellite data in describing stability development and the processes effecting its change also was evaluated. Of the terms...

Davis, James Gregory

1979-01-01

193

Stormtrack: Storm Chaser Homepage  

NSDL National Science Digital Library

Stormtrack, the storm chaser homepage, is an information-rich site geared toward general audiences. Along with up-to-the minute reports on exciting storm activity around the US, Stormtrack provides a library of chase logs and case studies, data links, weather maps, a message board and more. Miscellaneous topics posted at the site include the energy-helicicity index, hurricane and tornado damage, and the Oklahoma-based Storm Prediction Center. For serious weather buffs, there is also a page of equipment recommendations, a chat room,, and information on how to volunteer as a storm spotter.

194

Tropical Storms, Worldwide  

NSDL National Science Digital Library

The University of Hawaii's Mees Solar Observatory, stationed at Haleakala, Maui, provides a wealth of data and images in its Webpages. This page, Tropical Storms Worldwide, gives regional maps and written updates of hurricane, typhoon, and tropical cyclone activity around the globe. The page also features a strike probability calculator where users click on a list of geographic locations or enter map coordinates or a US zip code in order to view the probability of a tropical storm reaching that area. A storm data archive (1994-2000) and printer-friendly .pdf-formatted storm track maps are also available.

195

Inter-Annual Repeatability of Regional Dust Storms During the Martian Dusty Season (Invited)  

NASA Astrophysics Data System (ADS)

We investigate the annual pattern of large (regional) dust storms during the martian dusty season--southern spring and summer (Ls 180° to 360°)--and find a repeatable pattern of three distinct storms each Mars year without a global dust storm. We use a 200 K contour in the zonal mean climatology at 50 Pa from TES/MGS and MCS/MRO to identify the regional and global dust storms and then to characterize their extent and evolution. Observations from the two instruments cover the dusty season of five mars years without a global storm: MY24, MY26, MY29, MY30 and MY31. The exact timing, duration and peak temperatures vary somewhat from year to year, but each of the three storms has distinct characteristics and behavior, and overall the years follow a very similar pattern. Each year starts with an 'A' storm pre-perihelion (between Ls 210° and 240°) in the southern mid-latitudes. It lasts for 15° to 40° of Ls and ends no later than the solstice. The storm takes 2° to 12° of Ls to reach its peak zonal mean temperatures between 210 K and 230 K. The second storm ('B' storm) each year occurs as the 'A' storm is decaying. It starts around the perihelion along the southern seasonal polar cap edge and lasts until between Ls 285° and 295°. While the storm often has the strongest warming for the year (with zonal mean peak temperatures between 210 K and 225 K), the storm's impact remains south of the tropics. The final storm each year ('C' storm) starts between Ls 305° and 320°. It lasts a relatively short 3° to 15° of Ls. However, the later the storm starts seasonally, the longer it tends to last. The peak temperatures are quite variable for the 'C' storm, ranging from 200 K to 225 K. In MY26, the 'C' storm has the highest zonal mean temperatures for the season.

Kass, D. M.; Kleinboehl, A.; McCleese, D. J.; Schofield, J. T.; Smith, M. D.

2013-12-01

196

Summer Swimtime: Staying Healthy at the Pool and Beach  

MedlinePLUS

... the water. But recreational waters—including swimming pools, lakes and oceans—can sometimes get contaminated with bacteria ... in your summer plans. Natural water sources, including lakes, rivers and oceans, often get contaminated from storm ...

197

Storm Window Treatments  

NSDL National Science Digital Library

Students will be asked to analyze a given set of data to determine the best storm window treatments for a local company to use when building a new homes. Students will be asked to write a letter to the company explaining how they ranked the storm window treatments.

2012-12-03

198

STORM WATER MANAGEMENT MODEL  

EPA Science Inventory

Storm Water Management Model (SWMM) is a comprehensive model for analysis of quantity and quality problems associated with urban runoff. Both single-event and continuous simulation may be performed on catchments having storm sewers, combined sewers, and natural drainage, for pred...

199

Tropical Storm Cristobal  

NSDL National Science Digital Library

This animation shows Tropical Storm Cristobal on August 7, 2002 . Cristobal was located east of St. Augustine, Florida. The storm has had a maximum sustained wind speed of 45 MPH.Cristobal is expected to move east-northeast within the next 24 hours.

Lori Perkins

2002-08-07

200

Investigating Magnetic Storms  

NSDL National Science Digital Library

This is a lesson to introduce the Kp index, a common numerical indicator of magnetic storminess. Learners will access and analyze Kp index plots of magnetic storm strength and determine the relative frequency of stronger versus weaker magnetic storms. This is the fourteenth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

2012-08-03

201

Storms in Space  

Microsoft Academic Search

Imagine what an extra-terrestrial Weather Channel would be like, with a professional space weatherman as your forecaster, and you get rather close to the astounding aspects of nature described in John Freeman's Storms in Space. Known only to a handful of space scientists, yet capable of disrupting technical systems as extensive as communication satellites and electric power grids Storms in

John W. Freeman

2001-01-01

202

Catastrophic Storms, El Nino, and Patch Stability in a Southern California Kelp Community  

Microsoft Academic Search

Strong winter storms in southern California destroyed most of the canopy of the giant kelp Macrocystis pyrifera but not the patches of understory kelps in the Point Loma kelp forest near San Diego. Subsequent massive recruitment of Macrocystis juveniles and adults that survived the storms had low survival in the summer during the California El Nino of 1983. The combined

Paul K. Dayton; Mia J. Tegner

1984-01-01

203

Structure of Highly Sheared Tropical Storm Chantal during CAMEX-4.  

NASA Astrophysics Data System (ADS)

Tropical Storm Chantal during August 2001 was a storm that failed to intensify over the few days prior to making landfall on the Yucatan Peninsula. An observational study of Tropical Storm Chantal is presented using a diverse dataset including remote and in situ measurements from the NASA ER-2 and DC-8 and the NOAA WP-3D N42RF aircraft and satellite. The authors discuss the storm structure from the larger-scale environment down to the convective scale. Large vertical shear (850 200-hPa shear magnitude range 8 15 m s-1) plays a very important role in preventing Chantal from intensifying. The storm had a poorly defined vortex that only extended up to 5 6-km altitude, and an adjacent intense convective region that comprised a mesoscale convective system (MCS). The entire low-level circulation center was in the rain-free western side of the storm, about 80 km to the west-southwest of the MCS. The MCS appears to have been primarily the result of intense convergence between large-scale, low-level easterly flow with embedded downdrafts, and the cyclonic vortex flow. The individual cells in the MCS such as cell 2 during the period of the observations were extremely intense, with reflectivity core diameters of 10 km and peak updrafts exceeding 20 m s-1. Associated with this MCS were two broad subsidence (warm) regions, both of which had portions over the vortex. The first layer near 700 hPa was directly above the vortex and covered most of it. The second layer near 500 hPa was along the forward and right flanks of cell 2 and undercut the anvil divergence region above. There was not much resemblance of these subsidence layers to typical upper-level warm cores in hurricanes that are necessary to support strong surface winds and a low central pressure. The observations are compared to previous studies of weakly sheared storms and modeling studies of shear effects and intensification.The configuration of the convective updrafts, low-level circulation, and lack of vertical coherence between the upper- and lower-level warming regions likely inhibited intensification of Chantal. This configuration is consistent with modeled vortices in sheared environments, which suggest the strongest convection and rain in the downshear left quadrant of the storm, and subsidence in the upshear right quadrant. The vertical shear profile is, however, different from what was assumed in previous modeling in that the winds are strongest in the lowest levels and the deep tropospheric vertical shear is on the order of 10 12 m s-1.

Heymsfield, G. M.; Halverson, J.; Ritchie, E.; Simpson, Joanne; Molinari, J.; Tian, L.

2006-01-01

204

Structure of Highly Sheared Tropical Storm Chantal during CAMEX-4  

NASA Technical Reports Server (NTRS)

Tropical Storm Chantal during August 2001 was a storm that failed to intensify over the few days prior to making landfall on the Yucatan Peninsula. An observational study of Tropical Storm Chantal is presented using a diverse dataset including remote and in situ measurements from the NASA ER-2 and DC-8 and the NOAA WP-3D N42RF aircraft and satellite. The authors discuss the storm structure from the larger-scale environment down to the convective scale. Large vertical shear (850-200-hPa shear magnitude range 8-15 m/s) plays a very important role in preventing Chantal from intensifying. The storm had a poorly defined vortex that only extended up to 5-6-km altitude, and an adjacent intense convective region that comprised a mesoscale convective system (MCS). The entire low-level circulation center was in the rain-free western side of the storm, about 80 km to the west-southwest of the MCS. The MCS appears to have been primarily the result of intense convergence between large-scale, low-level easterly flow with embedded downdrafts, and the cyclonic vortex flow. The individual cells in the MCS such as cell 2 during the period of the observations were extremely intense, with reflectivity core diameters of 10 km and peak updrafts exceeding 20 m/s. Associated with this MCS were two broad subsidence (warm) regions, both of which had portions over the vortex. The first layer near 700 hPa was directly above the vortex and covered most of it. The second layer near 500 hPa was along the forward and right flanks of cell 2 and undercut the anvil divergence region above. There was not much resemblance of these subsidence layers to typical upper-level warm cores in hurricanes that are necessary to support strong surface winds and a low central pressure. The observations are compared to previous studies of weakly sheared storms and modeling studies of shear effects and intensification. The configuration of the convective updrafts, low-level circulation, and lack of vertical coherence between the upper- and lower-level warming regions likely inhibited intensification of Chantal. This configuration is consistent with modeled vortices in sheared environments, which suggest the strongest convection and rain in the downshear left quadrant of the storm, and subsidence in the upshear right quadrant. The vertical shear profile is, however, different from what was assumed in previous modeling in that the winds are strongest in the lowest levels and the deep tropospheric vertical shear is on the order of 10-12 m/s.

Heymsfield, G. M.; Halverson, J.; Ritchie, E.; Simpson, Joanne; Molinari, J.; Tian, L.

2006-01-01

205

Convection Movies  

NSDL National Science Digital Library

This page, on the website of Stephane Labrosse of ENS Lyon, presents some examples of flow motions resulting from convection calculations in different situations. All are for infinite Prandtl number and free-slip boundary conditions on horizontal surfaces

Stephane Labrosse

206

Arctic Summer Ice Processes  

NASA Technical Reports Server (NTRS)

The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open water, temporal change) using spaceborne SAR data obtained during the summer of 1998, and compare these results with an ocean and ice model of summer melt. Additional information is contained in the original.

Holt, Benjamin

1999-01-01

207

The Impacts of Chihuahua Desert Aerosol Intrusions on Convective Clouds and Regional Precipitation  

NASA Astrophysics Data System (ADS)

Growing up in a desert region influenced by a monsoon system and experiencing, first-hand, dust storms produced by convective thunderstorms stimulated my interest in the study of the impacts of aerosols on clouds. Contrary to other studies which focus more on anthropogenic aerosols, I chose to investigate the role of natural aerosols in the deserts of North America. Moreover, the role played by aerosols in desert regions within the North American Monsoon domain has not received as much attention as in other monsoon regions around the world. This dissertation describes my investigation of the connection between mineral aerosols (dust storms) and monsoon rainfall in the deserts of the Southwestern United States and Northwestern Mexico. To develop the context for the study of the role of mineral dust in summer-time convection on a regional scale, large-scale dynamical processes and their impact on the inter-annual variability of monsoon rainfall were analyzed. I developed the climatology of monsoonal rainfall and dust storms using surface observations to determine which mesoscale features influence North American Monsoon rainfall in the Paso Del Norte region. The strongest correlations were found between sea surface temperatures over the Gulf of California, Gulf of California moisture surges and monsoon rainfall in the Paso Del Norte region. A connection to ENSO could not be clearly established despite analyzing twenty-one years of data. However, by breaking the data into segments, a strong correlation was found for periods of intense rainfall. Twenty-one case studies were identified in which dust storms were produced in conjunction with thunderstorms during the 2005 - 2007 monsoon seasons. However, in some cases all the conditions were there for rainfall to occur but it did not precipitate. I concluded that strong thunderstorm outflow was triggering dust storms. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem V3.1.1) was used to evaluate the model's sensitivity to the inclusion of aerosol effects on cloud drop formation and on direct radiative forcing. A comparison of the relative contribution of aerosol direct and indirect forcings in terms of differences in aerosol and cloud optical thicknesses, cloud water content, cloud droplet number, and short wave and long wave radiation, revealed that cloud cover is reduced. This suggests that Chihuahua desert dust affects cloud formation.

Apodaca, Karina

208

Meteorology, Macrophysics, Microphysics, Microwaves, and Mesoscale Modeling of Mediterranean Mountain Storms: The M8 Laboratory  

NASA Technical Reports Server (NTRS)

Comprehensive understanding of the microphysical nature of Mediterranean storms can be accomplished by a combination of in situ meteorological data analysis and radar-passive microwave data analysis, effectively integrated with numerical modeling studies at various scales, from synoptic scale down through the mesoscale, the cloud macrophysical scale, and ultimately the cloud microphysical scale. The microphysical properties of and their controls on severe storms are intrinsically related to meteorological processes under which storms have evolved, processes which eventually select and control the dominant microphysical properties themselves. This involves intense convective development, stratiform decay, orographic lifting, and sloped frontal lifting processes, as well as the associated vertical motions and thermodynamical instabilities governing physical processes that affect details of the size distributions and fall rates of the various types of hydrometeors found within the storm environment. Insofar as hazardous Mediterranean storms, highlighted in this study by three mountain storms producing damaging floods in northern Italy between 1992 and 2000, developing a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution and the heterogeneous nature of precipitation fields within a storm domain. This involves convective development, stratiform transition and decay, orographic lifting, and sloped frontal lifting processes. This also involves vertical motions and thermodynamical instabilities governing physical processes that determine details of the liquid/ice water contents, size disi:ributions, and fall rates of the various modes of hydrometeors found within hazardous storm environments.

Starr, David O. (Technical Monitor); Smith, Eric A.

2002-01-01

209

New insights on geomagnetic storms from observations and modeling  

SciTech Connect

Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzstorms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

Jordanova, Vania K [Los Alamos National Laboratory

2009-01-01

210

Exploring the Differences in Deep Convective Transport Characteristics Between Quasi-Isolated Strong Convection and Mesoscale Convective Systems Using Seasonal WRF Simulations  

NASA Astrophysics Data System (ADS)

It has been shown in several previous studies that there is a relationship between mesoscale storm type and deep convective mass transport characteristics. For example, a previous simulation study showed that a supercell storm transported significantly more tracers into the stratosphere than did a multicell storm in an environment with identical thermodynamic structure. We utilize the Weather Research and Forecasting (WRF) model (version 3.2.1) with chemistry to simulate mass transport during the convective season of 2007 in the U.S. Southern Great Plains at convection-resolving scale (2 km). The storms that were resolved in the model were then classified using an object-based classification scheme. This classification scheme, which is based on schemes used in the mesoscale observational community, uses model-derived radar reflectivity (a function of precipitation hydrometeors) to classify storm type as either weak convection, quasi-isolated strong convection (QISC), mesoscale convective system (MCS), or linear MCS. This study focuses on examining the differences between the QISC and MCS regimes. Differences on the domain-scale are determined by investigation of two transport parameters: the level of maximum detrainment (LMD) and the magnitude of newly transport mass. Based on total transport over the entire region, results have shown that there are some significant differences between regimes. The mean LMD is 540 m higher in the MCS regime than in the QISC regime in July, but the LMD is very similar in the two regimes in May (only 150 m difference in the means). Conversely, the magnitude of newly transported mass in the MCS and QISC is not significantly different in July (MCS greater by a factor of 1.4), but is significantly different in May (MCS regime 1.8 times greater than QISC). At a per storm scale, differences were determined by analysis of the magnitude of transport per deeply convective object and the LMD relative to the height of the tropopause. The tropopause-relative LMD followed the domain-wide results, where there were significant differences in July (MCS regime mean altitude relative to the tropopause higher by 840 m to the QISC regime) but the regimes transported to similar altitudes in May (difference in the means is 70 m, favoring the MCS regime). There were significant differences in the magnitude of transport per deeply convective object for both May and July, where in May the MCS transported 2.2 times the mass per storm than the QISC regime, and in July the MCS transported 2.1 times more mass per storm than did the QISC regime.

Bigelbach, B. C.; Mullendore, G. L.; Starzec, M.; Jorgenson, S.

2013-12-01

211

Evaluation of European Storm Forecast Experiment (ESTOFEX) forecasts  

Microsoft Academic Search

Three years of forecasts of lightning and severe thunderstorms from the European Storm Forecast Experiment (ESTOFEX) have been evaluated. The forecasts exhibit higher quality in summer than in winter and there is some evidence that they have improved over the course of the evaluation. Five individual forecasters made the majority of the forecasts and differences in their forecasts are on

H. E. Brooks; P. T. Marsh; A. M. Kowaleski; P. Groenemeijer; T. E. Thompson; C. S. Schwartz; C. M. Shafer; A. Kolodziej; N. Dahl; D. Buckey

2011-01-01

212

Dusty gust fronts and their contributions to long-lived convection in West Africa/  

E-print Network

To model and predict the behavior of West African storms and mesoscale convective systems (MCSs), we must understand the life cycle of gust fronts, which invariably accompany thunderstorms and often initiate them. In this ...

McGraw-Herdeg, Michael (Michael P.)

2010-01-01

213

Severe convection and lightning in subtropical South America By Kristen L. Rasmussen1  

E-print Network

1 Severe convection and lightning in subtropical South America of the seasonal, diurnal, and extreme storm-related lightning in South America. · Preference for hail and lightning concentrate over the foothills of western Argentina. Lightning has a nocturnal maximum

Houze Jr., Robert A.

214

A climatology of springtime convection systems over the Northwest Gulf of Mexico and adjacent coasts  

E-print Network

of the relationship between the synoptic-scale environment with the structure and evolution of these storms. Particular attention was given to synoptic-scale factors that affect convective organization. Climatological attributes such as diurnal characteristics...

Hashem, Magda Sami

1996-01-01

215

The 2008 Super Tuesday Tornado Outbreak: Overview of the Tornadoes and their Parent Storms  

NASA Technical Reports Server (NTRS)

The cold-season Tornado outbreak that occurred over the Southeast on 5-6 February 2008 was significant for the following reasons: about 84 tornadoes were documented over a 15 h period between late afternoon on 5 February and early morning on 6 February 2008; a wide variety of parent storms were associated with the tornadoes; a total of five EF-4 tornadoes occurred, with two forming over Alabama during the early morning hours prior to sunrise; there was a significant lull period between the initial convective and the early morning activity over Alabama 10 hours later; and, a wide spectrum of storm types, ranging from isolated supercell storms to QLCS bow echoes, accompanied the tornadoes. The goal of this paper is to provide a general description of the outbreak including the distribution of tornadoes and supercell storms over the region, a detailed map of the tornado tracks, time series of tornadoes and parent storms, and general characteristics of all parent tornado storms. The total number of major storms (duration greater than 3 h, at least three tornadoes produced) was seven. Several noteworthy storms are described: a long track (198 km long) tornado and its parent storm over Arkansas; a prolific supercell storm persisted for 7-8 hours and produced 16 tornadoes from north-central Mississippi to southern KY; and, bow echo storms (QLCS's) were simultaneous over KY and produced 16 tornadoes.

Knupp, Kevin R.; Coleman, Tim; Carey, Larry; Petersen, Walt

2008-01-01

216

Choice of South Asian Summer Monsoon Indices.  

NASA Astrophysics Data System (ADS)

In the south Asian region, two of the major precipitation maxima associated with areas of intensive convective activity are located near the Bay of Bengal and in the vicinity of the Philippines. The variations of monthly mean outgoing longwave radiation in the two regions are poorly correlated, particularly in the decade of 1980s. The enhanced convection over the Bay of Bengal and Indian subcontinents is coupled with reinforced monsoon circulation west of 80°E over India, the western Indian Ocean, and the tropical northern Africa. In contrast, the enhanced convection in the vicinity of the Philippines corresponds to intensified monsoon circulation primarily east of 80°E over southeast Asia including the Indochina peninsula, South China Sea, Philippine Sea, and the Maritime Continent. To better reflect regional monsoon characteristics, two convection indices (or associated circulation indices that are dynamically coherent with the convection indices) are suggested to measure the variability of the Indian summer monsoon (ISM) and the southeast Asian summer monsoon, respectively.The change in the Bay of Bengal convection (the ISM) has planetary-scale implications, whereas the change in Philippine convection has primarily a regional impact including a linkage with the east Asia subtropical monsoon. The equatorial western Pacific winds exhibit a considerably higher correlation with the ISM convection than with the Philippine convection. During the summers when a major Pacific warm episode occurs (e.g., 1982-83, 1986-87, 1991-92, and 1997), the convection and circulation indices describing the ISM often diverge considerably, causing inconsistency among various normally coherent monsoon indices. This poses a primary difficulty for using a single monsoon index to characterize the interannual variability of a regional monsoon. The cause of the breakdown of the coherence between various convection and circulation indices during ENSO warm phase needs to be understood.

Wang, Bin; Fan, Zhen

1999-04-01

217

Observation and numerical simulation of a convective initiation during COHMEX  

NASA Technical Reports Server (NTRS)

Under a synoptically undisturbed condition, a dual-peak convective lifecycle was observed with the COoperative Huntsville Meteorological EXperiment (COHMEX) observational network over a 24-hour period. The lifecycle included a multicell storm, which lasted about 6 hours, produced a peak rainrate exceeding 100 mm/hr, and initiated a downstream mesoscale convective system. The 24-hour accumulated rainfall of this event was the largest during the entire COHMEX. The downstream mesoscale convective system, unfortunately, was difficult to investigate quantitatively due to the lack of mesoscale observations. The dataset collected near the time of the multicell storm evolution, including its initiation, was one of the best datasets of COHMEX. In this study, the initiation of this multicell storm is chosen as the target of the numerical simulations.

Song, J. Aaron; Kaplan, Michael L.

1991-01-01

218

The moisture budget in relation to convection  

NASA Technical Reports Server (NTRS)

An evaluation of the moisture budget in the environment of convective storms is presented by using the unique 3- to 6-h rawinsonde data. Net horizontal and vertical boundary fluxes accounted for most of the large amounts of moisture which were concentrated into convective regions associated with two squall lines that moved through the area during the experiment. The largest values of moisture accumulations were located slightly downwind of the most intense convective activity. Relationships between computed moisture quantities of the moisture budget and radar-observed convection improved when lagging the radar data by 3 h. The residual of moisture which represents all sources and sinks of moisture in the budget equation was largely accounted for by measurements of precipitation.

Scott, R. W.; Scoggins, J. R.

1977-01-01

219

Winter Storm Fire Safety  

MedlinePLUS

... electrical fires. Encourage safe holiday decoration displays, including candles. Suggest ways to safely cook indoors. Outreach materials ... fire #safetytip: always use a flashlight - not a candle - for emergency lighting. Facebook During a winter storm, ...

220

Hurricane: Storm Science  

NSDL National Science Digital Library

This site presents a good overall introduction to hurricane science at the elementary level. Topics include: Weather Instruments, Killer Storms, Surviviors, and Inside a Hurricane. Each section has activites and/or simple explanations of the topic.

2000-01-01

221

Why do Tornados and Hail Storms Rest on Weekends?  

NASA Technical Reports Server (NTRS)

When anthropogenic aerosols over the eastern USA during summertime are at their weekly mid-week peak, tornado and hail storm activity there is also near its weekly maximum. The weekly cycle in storm activity is statistically significant and unlikely to be due to natural variability. The pattern of variability supports the hypothesis that air pollution aerosols invigorate deep convective clouds in a moist, unstable atmosphere, to the extent of inducing production of large hailstones and tornados. This is caused by the effect of aerosols on cloud-drop nucleation, making cloud drops smaller, delaying precipitation-forming processes and their evaporation, and hence affecting cloud dynamics.

Rosenfeld, Daniel; Bell, Thomas L.

2010-01-01

222

Dust storm in Sudan  

NASA Technical Reports Server (NTRS)

A dust storm is carrying dust from Sudan, Africa, out over the Red Sea (right) in this Moderate Resolution Imaging Spectroradiometer Image from June 30, 2002. In the lower left quadrant of the image, the sinuous path of the Nile can be seen. Dust storms such as this reduce the amount of solar radiation that reaches the surface, and have a cooling effect on the area. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

223

Identification of Robust Terminal-Area Routes in Convective Weather  

E-print Network

Convective weather is responsible for large delays and widespread disruptions in the U.S. National Airspace System, especially during summer. Traffic flow management algorithms require reliable forecasts of route blockage ...

Balakrishnan, Hamsa

224

Hurricane and Severe Storm Sentinel (HS3)  

NASA Astrophysics Data System (ADS)

HS3 is one of five projects in NASA's Earth Venture program. The goal of HS3 is to enhance our understanding of the processes that underlie hurricane intensity change in the Atlantic Ocean basin. HS3 is motivated by hypotheses related to the roles of the large-scale environment and storm internal processes in hurricane intensity change as well as the controversial role of the Saharan Air Layer (SAL) in tropical storm formation and intensification, the role of deep convection in the inner-core region of storms, and the evolution of storm structure and intensity during the process of transition into a more extratropical system. The HS3 objectives are: (1) to obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers and (2) to observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. Past hurricane field campaigns have all faced the limitation of a relatively small sample of storms forming under a variety of scenarios and undergoing widely varying evolutions. The small sample is not only a function of tropical storm activity in any given year, but also the distance of storms from the base of operations. Addressing the science questions posed by HS3 requires sustained measurements over several years. HS3 will conduct a total of ten 30-hour flights during each of three one-month deployments using two NASA Global Hawk UASs. From mid-August to mid-September during 2012-2014, HS3 will be deployed from the NASA Wallops Flight Facility, providing access to unrestricted air space and unprecedented access to hurricanes over the Atlantic ocean. HS3 utilizes a suite of advanced instruments to measure key characteristics of the storm environment and the hurricane’s internal structures. The environmental payload will provide continuous sampling of temperature and relative humidity in the clear-air environment from the scanning High-resolution Interferometer Sounder (HIS), full tropospheric wind, temperature, and humidity profiles from the Advanced Vertical Atmospheric Profiling System (AVAPS) dropsonde system, continuous wind profiles in clear air from the TWiLiTE Doppler wind lidar, and aerosol and cloud layer vertical structure from the Cloud Physics Lidar (CPL). The over-storm payload measurements include three-dimensional wind and precipitation fields from the HIWRAP conically scanning Doppler radar, surface winds and rainfall from the Hurricane Imaging Radiometer (HIRAD) multi-frequency interferometric radiometer, and measurements of temperature, water vapor, and liquid water profiles, total precipitable water, sea-surface temperature, rain rates, and vertical precipitation profiles from the HAMSR microwave sounder. HS3 will provide a unique and comprehensive data set on a large number of Atlantic hurricanes to characterize the hurricane environment and internal structures. The HS3 measurements will be used enhance our understanding of hurricane intensification and, by coupling data analysis with both global and mesoscale modeling research, improve current Earth system modeling and prediction capabilities.

Braun, S. A.; Newman, P. A.; Vasques, M.

2010-12-01

225

Storm-Centered Ensemble Data Assimilation for Tropical Cyclones  

NASA Astrophysics Data System (ADS)

A significant challenge for tropical cyclone ensemble data assimilation is that storm-scale observations tend to make analyses that are more asymmetric than the prior forecasts. Compromised structure and intensity, such as an increase of amplitude across the azimuthal Fourier spectrum, are a routine property of ensemble-based analyses, even with accurate position observations and frequent assimilation. Storm dynamics in subsequent forecasts evolve these states toward axisymmetry, creating difficulty in distinguishing between model-induced and actual storm asymmetries for predictability studies and forecasting. To address this issue, we propose here a novel algorithm using a storm-centered approach. The method is designed for use with existing ensemble filters with little or no modification, facilitating its adoption and maintenance. The algorithm consists of: (1) an analysis of the environment using conventional coordinates, (2) a storm-centered analysis using storm-relative coordinates, and (3) a merged analysis that combines the large-scale and storm-scale fields together at an updated storm location. The storm-centered method is evaluated for two sets of experiments: no-cycling tests of the update step for idealized, three-dimensional storms in radiative--convective equilibrium, and full cycling tests of data assimilation applied shallow-water model for a field of interacting vortices. In both cases results are compared against a control based on a conventional ensemble Kalman filter scheme. Results show that storm-relative assimilation yields vortices that are more symmetric and exhibit finer inner-core structure than for the control, with errors reduced by an order of magnitude as compared to a control with prior spread similar to the National Hurricane Center's 12~h mean track error in 12~h forecasts. Azimuthal Fourier error spectra exhibit much-reduced noise associated with data assimilation as compared to the conventional EnKF scheme. An assessment of the affect of the merge step on balance reveals a similar, balanced trend in free-surface height tendency between the storm-centered and conventional EnKF approaches, with storm-centered values more closely resembling the reference state.

Navarro, Erika L.

226

The Diagnosis and application of a convective vorticity vector associated with convective systems  

NASA Astrophysics Data System (ADS)

Although dry/moist potential vorticity is a very useful and powerful physical quantity in the large scale dynamics, it is not a quite ideal dynamical tool for the study of convective systems or severe storms. A new convective vorticity vector (CVV) is introduced in this study to identify the development of convective systems or severe storms. The daily Aviation (AVN) Model Data is used to diagnose the distribution of the CVV associated with rain storms occurred in the period of Meiyu in 1998. The results have clearly demonstrated that the CVV is an effective vector for indicating the convective actions along the Meiyu front. The CVV also is used to diagnose a 2-D cloud-resolving simulation data associated with 2-D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the Tropical cean-Global tmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2-D x-z frame. Analysis of zonally averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

Gao, S.; Zhou, Y.; Tao, W.

2005-05-01

227

Trajectory analysis of Saudi Arabian dust storms  

NASA Astrophysics Data System (ADS)

Temporal and spatial characteristics of Saudi Arabian dust storms, with focus on associated air parcel trajectories, are investigated using station and gridded weather observations and remotely-sensed aerosol optical depth (AOD). For 13 focal stations, an extensive pool of 84-h backward trajectories is developed for dust storm days, and the trajectories are grouped into 3-5 representative clusters based on the K-means technique and Silhouette Coefficients. Saudi Arabian dust storms are most prominent during February-June, with a mid-winter peak along the southern coast of the Red Sea, spring peak across northern Saudi Arabia around the An Nafud Desert, and early summer peak in eastern Saudi Arabia around the Ad Dahna Desert. Based on backward trajectories, the primary local dust source is the Rub Al Khali Desert and the primary remote sources are the Saharan Desert, for western Saudi Arabia, and Iraqi Deserts, for northern and eastern Saudi Arabia. During February-April, the Mediterranean storm track is active, with passing cyclones and associated cold fronts carrying Saharan dust to Saudi Arabian stations along the northern coast of the Red Sea. Across Saudi Arabia, the highest AOD is achieved during dust storms that originate from the Rub Al Khali and Iraqi Deserts. Most stations are dominated by local dust sources (primarily Rub Al Khali), are characterized by three dominant trajectory paths, and achieve AOD values exceeding 1. In contrast, for stations receiving predominantly remote dust (particularly Saharan), 3-5 trajectory paths emerge and AOD values only reach approximately 0.6 as dust is lost during transport.

Notaro, Michael; Alkolibi, Fahad; Fadda, Eyad; Bakhrjy, Fawzieh

2013-06-01

228

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01

229

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1995-01-01

230

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1996-01-01

231

Modeling Convection  

ERIC Educational Resources Information Center

Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…

Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda

2004-01-01

232

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

Prueitt, M.L.

1996-01-16

233

Convection Current  

NSDL National Science Digital Library

In this activity, learners make their own heat waves in an aquarium. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen. Use this demonstration to show convection currents in water as well as light refraction in a simple, visually appealing way.

The Exploratorium

2012-06-26

234

Convection Activities  

NSDL National Science Digital Library

This page presents activities related to Convection from the Science & Engineering in the Lives of Students project. Activities include Candle Heat, Freezer Air Temperature, Hot Cup, Pencil Shaving, and Speed Melting. Each activity includes a detailed description, list of the materials needed, science concepts covered, and reflection questions.

235

Effects of Deep Convection on Atmospheric Chemistry  

NASA Technical Reports Server (NTRS)

This presentation will trace the important research developments of the last 20+ years in defining the roles of deep convection in tropospheric chemistry. The role of deep convection in vertically redistributing trace gases was first verified through field experiments conducted in 1985. The consequences of deep convection have been noted in many other field programs conducted in subsequent years. Modeling efforts predicted that deep convection occurring over polluted continental regions would cause downstream enhancements in photochemical ozone production in the middle and upper troposphere due to the vertical redistribution of ozone precursors. Particularly large post-convective enhancements of ozone production were estimated for convection occurring over regions of pollution from biomass burning and urban areas. These estimates were verified by measurements taken downstream of biomass burning regions of South America. Models also indicate that convective transport of pristine marine boundary layer air causes decreases in ozone production rates in the upper troposphere and that convective downdrafts bring ozone into the boundary layer where it can be destroyed more rapidly. Additional consequences of deep convection are perturbation of photolysis rates, effective wet scavenging of soluble species, nucleation of new particles in convective outflow, and the potential fix stratosphere-troposphere exchange in thunderstorm anvils. The remainder of the talk will focus on production of NO by lightning, its subsequent transport within convective clouds . and its effects on downwind ozone production. Recent applications of cloud/chemistry model simulations combined with anvil NO and lightning flash observations in estimating NO Introduction per flash will be described. These cloud-resolving case-study simulations of convective transport and lightning NO production in different environments have yielded results which are directly applicable to the design of lightning parameterizations for global chemical transport models. The range of mean values (factor of 3) of NO production per flash (or per meter of lightning channel length) that have been deduced from the model will be shown and compared with values of production in the literature that have been deduced using other methods, Results show that on a per flash basis, IC flashes are nearly as productive of NO as CG flashes. When combined with the global flash rate of 44 flashes per second from NASA's Optical Transient Detector (OTD) measurements, these estimates and the results from other techniques yield global NO production rates of 2-9 TgN/year. Vertical profiles of lightning NOx mass at the end of the 3-D storm simulations have been summarized to yield suggested profiles for use in global models. Simulations of the photochemistry over the 24 hours following a storm have been performed to determine the additional ozone production which can be attributed to lightning NO.

Pickering, Kenneth E.

2007-01-01

236

Dynamic Reconfiguration of Terminal Airspace During Convective Weather  

E-print Network

Dynamic Reconfiguration of Terminal Airspace During Convective Weather Diana Michalek and Hamsa research has largely focused on enroute airspace in clear weather conditions, the principle of better are often impacted by congestion due to convective weather, especially during summer months when travel

Gummadi, Ramakrishna

237

Into the Eye of the Storm  

NASA Technical Reports Server (NTRS)

MISR acquired this stereoimage of Hurricane Alberto on August 19, 2000 during Terra orbit 3571. At this time, the storm was located in the North Atlantic Ocean, about 1700 kilometers west of the Azores. According to the National Weather Service, Alberto was increasing in intensity and exhibiting maximum sustained winds of about 165 kilometers per hour.

This stereo 'anaglyph' image was generated using MISR's vertical (nadir)camera plus the 26-degree forward-viewing camera. It is oriented so that the spacecraft's flight path is from left to right. North is at the left. To view the image in 3-D, use red/blue glasses with the red filter over your left eye.

Near the center of the storm, the 'eye' measures about 60 kilometers in diameter. The steep eye wall, where surface winds reach their peak intensity, is very apparent. Convective thunderclouds are present in the storm's spiral arms, and their three-dimensional structure is visible in this stereo view.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

For more information: http://www-misr.jpl.nasa.gov

2000-01-01

238

Nontornadic convective wind fatalities in the United States  

Microsoft Academic Search

A database was compiled for the period 1977–2007 to assess the threat to life in the conterminous United States from nontornadic\\u000a convective wind events. This study reveals the number of fatalities from these wind storms, their causes, and their unique\\u000a spatial distributions. Nontornadic convective wind fatalities occur most frequently outdoors, in vehicles including aircraft,\\u000a or while boating. Fatalities are most

Alan W. BlackWalker; Walker S. Ashley

2010-01-01

239

MAMS data for the Convection and Moisture Experiment (CAMEX)  

NASA Technical Reports Server (NTRS)

During the fall of 1993, NASA sponsored a field program called the Convection And Moisture Experiment (CAMEX). The field effort focused on: convective storms in order to investigate their associated electrical properties, precipitation, and predictability, and atmospheric moisture studies. The data collected from the Multispectral Atmospheric Mapping Sensor (MAMS) onboard a NASA ER-2 aircraft which was deployed out of NASA/Wallops Flight Facility, Wallops Island, Virginia, from 11 Sep. through 7 Oct., 1993, is described.

Guillory, A. R.; Jedlovec, G. J.; Atkinson, R. J.

1994-01-01

240

Diagnostics of severe convection and subsynoptic scale ageostrophic circulations  

NASA Technical Reports Server (NTRS)

Diagnostics of severe convection and subsynoptic scale ageostrophic circulations are reported. Mesoscale circulations through forcing of ageostrophic motion by adiabatic, diabatic and frictional processes were studied. The development and application of a hybrid isentropic sigma coordinate numerical model was examined. The numerical model simulates mesoscale ageostrophic circulations associated with propagating jet streaks and severe convection. A complete list of publications and these completed through support of the NASA severe storms research project is included.

1985-01-01

241

On extreme geomagnetic storms  

NASA Astrophysics Data System (ADS)

Extreme geomagnetic storms are considered as one of the major natural hazards for technology-dependent society. Geomagnetic field disturbances can disrupt the operation of critical infrastructures relying on space-based assets, and can also result in terrestrial effects, such as the Quebec electrical disruption in 1989. Forecasting potential hazards is a matter of high priority, but considering large flares as the only criterion for early-warning systems has demonstrated to release a large amount of false alarms and misses. Moreover, the quantification of the severity of the geomagnetic disturbance at the terrestrial surface using indices as Dst cannot be considered as the best approach to give account of the damage in utilities. High temporal resolution local indices come out as a possible solution to this issue, as disturbances recorded at the terrestrial surface differ largely both in latitude and longitude. The recovery phase of extreme storms presents also some peculiar features which make it different from other less intense storms. This paper goes through all these issues related to extreme storms by analysing a few events, highlighting the March 1989 storm, related to the Quebec blackout, and the October 2003 event, when several transformers burnt out in South Africa.

Cid, Consuelo; Palacios, Judith; Saiz, Elena; Guerrero, Antonio; Cerrato, Yolanda

2014-10-01

242

Solar Radiation Storm  

NSDL National Science Digital Library

This past week has offered much excitement for space weather scientists and enthusiasts, alike. On Friday July 14, a major flare shot off the surface of the sun, pummeling Earth with a massive solar-radiation storm that interfered with satellite and radio communications and delayed a Russian space launch. The flare was one of the most powerful of the current eleven-year solar cycle (and the biggest solar radiation event since 1989) and was followed by a coronal mass ejection -- "a blast of billions of tons of electrically charged atomic particles and magnetic energy hurled in the Earth's direction at 3 million miles an hour" (1). When a very powerful coronal mass ejection hits the Earth's magnetosphere, a shock wave can compress the magnetosphere and unleash a geomagnetic storm -- causing interference with electric power transmission and triggering beautiful aurorae. Friday's flare was one of three storms last week, and the biggest since a small solar storm made the news in June (see the June 9, 2000 Scout Report for additional resources). Although this weekend's storms have diminished, more activity is anticipated as the sunspot group that is producing flares (region 9077) will continue to face the earth for another week.

Payne, Laura X.

243

Banded ion morphology - Main and recovery storm phases  

NASA Technical Reports Server (NTRS)

The occurrence of bands in ion spectra obtained with the high-altitude and low-altitude plasma instruments on DE-1 and DE-2, respectively, during main and recovery storm phases from the period September 1981 - January 1982 is analyzed statistically. Typical spectra are shown; diagrams and graphs of storm morphology are provided; and two theoretical models (one based on time-of-flight effects and another based on convective dispersion) are discussed. It is found that bands occur more often in the main phase than in the recovery phase, and more often and at higher latitudes in the evening than before noon. From the stability of the bands and the dependence of energy on latitude it is inferred that convective dispersion plays a more important role than time-of-flight effects in the motion of heavy ions in the magnetosphere.

Frahm, R. A.; Reiff, P. H.; Winningham, J. D.; Burch, J. L.

1986-01-01

244

Extreme storm activity in North Atlantic and European region  

NASA Astrophysics Data System (ADS)

The extreme storm activity study over North Atlantic and Europe includes the analyses of extreme cyclone (track number, integral cyclonic intensity) and extreme storm (track number) during winter and summer seasons in the regions: 1) 55°N-80N, 50°W-70°E; 2) 30°N-55°N, 50°W-70°E. Extreme cyclones were selected based on cyclone centre pressure (P<=970 mbar). Extreme storms were selected from extreme cyclones based on wind velocity on 925 mbar. The Bofort scala was used for this goal. Integral cyclonic intensity (for region) includes the calculation cyclone centers number and sum of MSLP anomalies in cyclone centers. The analyses based on automated cyclone tracking algorithm, 6-hourly MSLP and wind data (u and v on 925 gPa) from the NCEP/NCAR reanalyses from January 1948 to March 2010. The comparision of mean, calculated for every ten years, had shown, that in polar region extreme cyclone and storm track number, and integral cyclonic intensity gradually increases and have maximum during last years (as for summer, as for winter season). Every ten years means for summer season are more then for winter season, as for polar, as for tropical region. Means (ten years) for tropical region are significance less then for polar region.

Vyazilova, N.

2010-09-01

245

Storm track response to climate change: Insights from simulations using an idealized dry GCM.  

NASA Astrophysics Data System (ADS)

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.

Mbengue, Cheikh; Schneider, Tapio

2013-04-01

246

Interactions Between Saharan Dust and Tropical Convection  

NASA Astrophysics Data System (ADS)

The Saharan Air Layer has been observed to influence hurricane development over the tropical Atlantic Ocean, and Saharan dust particles have been found within cirrus anvil crystals over the eastern and western Atlantic. However, interactions between dust layers and the microphysical and dynamic properties of tropical clouds are not well understood. While dust particles are known to act strongly as heterogeneous ice nuclei, they also can adsorb and absorb water and can act as cloud condensation nuclei. Potentially different effects of dust on convection are possible depending on the nucleating mode (droplet vs. ice). Additionally, tropical storms may influence the distribution and loading of dust within the atmosphere, with impacts on climate and ocean biogeochemistry. We studied interactions between Saharan dust and tropical convective systems, using airborne measurements and an improved version of the RAMS cloud-resolving model. Simulations of small storms and tropical cyclones were initialized with actual field data from the NAMMA field program. Tracking of dust mass throughout the storm was also implemented, so the location of dust and how much was removed through precipitation could be assessed. Results are discussed in relation to field measurements of dust in the anvil region, as well as tropical storm development and evolution.

Twohy, C. H.; Saleeby, S. M.; van den Heever, S. C.; Herbener, S.; DeMott, P. J.

2012-12-01

247

Kinetic energy budgets in areas of convection  

NASA Technical Reports Server (NTRS)

Synoptic scale budgets of kinetic energy are computed using 3 and 6 h data from three of NASA's Atmospheric Variability Experiments (AVE's). Numerous areas of intense convection occurred during the three experiments. Large kinetic energy variability, with periods as short as 6 h, is observed in budgets computed over each entire experiment area and over limited volumes that barely enclose the convection and move with it. Kinetic energy generation and transport processes in the smaller volumes are often a maximum when the enclosed storms are near peak intensity, but the nature of the various energy processes differs between storm cases and seems closely related to the synoptic conditions. A commonly observed energy budget for peak storm intensity indicates that generation of kinetic energy by cross-contour flow is the major energy source while dissipation to subgrid scales is the major sink. Synoptic scale vertical motion transports kinetic energy from lower to upper levels of the atmosphere while low-level horizontal flux convergence and upper-level horizontal divergence also occur. Spatial fields of the energy budget terms show that the storm environment is a major center of energy activity for the entire area.

Fuelberg, H. E.

1979-01-01

248

The Sigüenza tornado: a case study based on convective ingredients concept and conceptual models  

Microsoft Academic Search

On 24 May 1993, part of the Iberian Peninsula was affected by convective activity concentrated on the eastern side of a low-level thermal boundary which was orientated north south. A series of storms evolved into a squall line striking at the province of Guadalajara (Central Spain). The southernmost cell of this mesoscale convective system generated a tornado that hit the

F. Martín; R. Riosalido; L. de Esteban

1997-01-01

249

Tropical Storm near Bermuda  

NASA Technical Reports Server (NTRS)

This unnamed tropical storm near Bermuda (26.5N, 59.5W) was the result of a strong mid-latitude low pressure system that formed over the Gulf Stream near Cape Hatteras. It rapidly developed into a spiral gyre with internal wind speeds of up to 50 knots and whipped up the sea surface with swells of 15 to 20 feet creating dangerous boating conditions. These sub-hurricane storms are frequent occurances in this region during the fall, winter and spring.

1992-01-01

250

A portable CW/FM-CW Doppler radar for local investigation of severe storms  

SciTech Connect

During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm. 2 refs., 2 figs.

Unruh, W.P.; Wolf, M.A.; Bluestein, H.B.

1988-01-01

251

Convection towers  

DOEpatents

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

Prueitt, M.L.

1994-02-08

252

Convection Demonstration  

NSDL National Science Digital Library

In this quick activity (located on page 2 of the PDF), learners will see the effects of convection and understand what makes hot air balloons rise. Learners will fill a bottle with hot water colored red and another bottle with cold water colored blue, then lower both into a container of water and observe the interaction of liquids of different temperatures/densities. Relates to the linked video, DragonflyTV GPS: Balloon Fiesta.

Twin Cities Public Television, Inc.

2007-01-01

253

Structure of Highly Sheared Tropical Storm Chantal during CAMEX-4 G. M. HEYMSFIELD,* J. HALVERSON, E. RITCHIE,# JOANNE SIMPSON,* J. MOLINARI,@ AND L. TIAN  

E-print Network

convection and rain in the downshear left quadrant of the storm, and subsidence in the upshear right quadrant coherence be- tween the upper- and lower-level warming regions likely inhibited intensification of Chantal

Ritchie, Elizabeth

254

Application and Study of Precipitation Schemes in Weather Simulation in Summer and Winter over China  

Microsoft Academic Search

Through simulation of summer and winter precipitation cases in China, the cloud precipitation schemes of model were examined. Results indicate that it is discrepant between convective precipitation simulated by the Kain-Fritsch (KF) scheme and Betts-Miller (BM) scheme in summer, the former scheme is better than the latter in this case. The ambient atmosphere may be varied by dieren t convective

XU Guoqiang; WAN Qilin; HUANG Liping; XUE Jishan; CHEN Dehui

255

Future changes in extratropical storm tracks and baroclinicity under climate change  

NASA Astrophysics Data System (ADS)

The weather in Eurasia, Australia, and North and South America is largely controlled by the strength and position of extratropical storm tracks. Future climate change will likely affect these storm tracks and the associated transport of energy, momentum, and water vapour. Many recent studies have analyzed how storm tracks will change under climate change, and how these changes are related to atmospheric dynamics. However, there are still discrepancies between different studies on how storm tracks will change under future climate scenarios. Here, we show that under global warming the CMIP5 ensemble of coupled climate models projects only little relative changes in vertically averaged mid-latitude mean storm track activity during the northern winter, but agree in projecting a substantial decrease during summer. Seasonal changes in the Southern Hemisphere show the opposite behaviour, with an intensification in winter and no change during summer. These distinct seasonal changes in northern summer and southern winter storm tracks lead to an amplified seasonal cycle in a future climate. Similar changes are seen in the mid-latitude mean Eady growth rate maximum, a measure that combines changes in vertical shear and static stability based on baroclinic instability theory. Regression analysis between changes in the storm tracks and changes in the maximum Eady growth rate reveal that most models agree in a positive association between the two quantities over mid-latitude regions.

Lehmann, Jascha; Coumou, Dim; Frieler, Katja; Eliseev, Alexey V.; Levermann, Anders

2014-08-01

256

Summer Astronomy  

ERIC Educational Resources Information Center

This brief article describes what can be expected of the skies in the summer of 2004 with quite a few celestial thrills to anticipate. In addition to the planet viewing opportunities, there is a very rare Venus transit of the Sun and the annual Perseid meteor shower. The 2004 summer also marks both an end and beginning for the Cassini/Huygens…

Riddle, Bob

2004-01-01

257

Probability forecasts for storm surges  

E-print Network

Deltares DMI Workshop 28 August 2007, Probability forecasts for storm surges 1 #12;G G G G Storm surge forecasts Europe + Atlantic Water levels Global Atmosphere Observations North Sea G G G G Deltares DMI of a storm surge Users SVSD, DNZ, DZL, Water boards, KNMI G G G G Deltares DMI Workshop 28 August 2007

Stoffelen, Ad

258

The Perfect Storm  

NSDL National Science Digital Library

The National Oceanic and Atmospheric Administration (NOAA) provides these two Websites on weather. The second site is narrower in scope but still of interest to weather researchers and to the public at large. Here, NOAA offers historical information, satellite images, and detailed text on the agency's coverage of the now-famous monster storm of October 1991, which sank the Andrea Gail.

259

Weather Stations: Storms  

NSDL National Science Digital Library

In this activity, learners test how cornstarch and glitter in water move when disturbed. Learners compare their observations with videos of Jupiter's and Earth's storm movements. This activity is one station that can be combined with other stations for an hour and half lesson on weather patterns on Jupiter and Earth.

Lunar and Planetary Institute

2011-01-01

260

California's Perfect Storm  

ERIC Educational Resources Information Center

The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

Bacon, David

2010-01-01

261

Stories from the Storm  

ERIC Educational Resources Information Center

For four months, St. Paul's Episcopal School in the Lakeview neighborhood of New Orleans, Louisiana remained closed after Hurricane Katrina ravaged the entire city in August 2005. The storm left St. Paul's campus under nine feet of water for two weeks, destroying many buildings and the entire first floor of the campus. As the only remaining art…

Smoczynski, Carol

2007-01-01

262

Magnetic Storms in Brazil  

NASA Astrophysics Data System (ADS)

Magnetic storms result from atypical processes generated in the Sun, the interaction between the solar wind and the Earth's magnetosphere and the energization of particles in the magnetosphere. As consequence, magnetic storms may cause problems on radio communication, in satellites, GPS imprecision and induce geomagnetic induced currents that my cause saturation and damage of transformers. Magnetic storms are measured in magnetic observatories, where it is possible to observe large variations in the horizontal magnetic field. These variations are most visible in equatorial or low-latitude magnetograms. In this work, we use low latitude dataset from three magnetic observatories in Brazil: Vassouras (Rio de Janeiro) that presents data since 1915, Tatuoca (Pará) since 1957 and data from a new magnetic observatory that was installed in Pantanal (Brazil) on the 22nd October 2012. Vassouras and Pantanal observatories are in the region of the South Atlantic Magnetic Anomaly. External magnetic field interactions in this region are poorly known due to the lack of magnetic data. Tatuoca observatory is located in another important geomagnetic region: the equatorial electrojet. In this work we present the data processing of the recent geomagnetic time series in Pantanal Observatory and its comparison with Vassouras and Tatuoca observatories in Brazil. We analyse the main characteristics of magnetic storms in these observatories, as the sudden commencement and their duration.

Pinheiro, K.; Siqueira, F.

2013-05-01

263

STORM INLET FILTRATION DEVICE  

EPA Science Inventory

Five field tests were conducted to evaluate the effectiveness of the Storm and Groundwater Enhancement Systems (SAGES) device for removing contaminants from stormwater. The SAGES device is a three-stage filtering system that could be used as a best management practices (BMP) retr...

264

Magnetic Storms and Aurora  

NSDL National Science Digital Library

This is a lesson to investigate auroras. Learners will plot and compare the amount of energy dissipated by auroras in the northern hemisphere with the recorded Kp index of magnetic storm severity. This is the sixteenth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

2012-08-03

265

An Update to the Warm-Season Convective Wind Climatology of KSC/CCAFS  

NASA Technical Reports Server (NTRS)

Total of 1100 convective events in the 17-year warm-season climatology at KSC/CCAFS. July and August typically are the peak of convective events, May being the minimum. Warning and non-warning level convective winds are more likely to occur in the late afternoon (1900-2000Z). Southwesterly flow regimes and wind directions produce the strongest winds. Storms moving from southwesterly direction tend to produce more warning level winds than those moving from the northerly and easterly directions.

Lupo, Kevin

2012-01-01

266

Convective weather hazards in the Twin Cities Metropolitan Area, MN  

NASA Astrophysics Data System (ADS)

This dissertation investigates the frequency and intensity of severe convective storms, and their associated hazards, in the Twin Cities Metropolitan Area (TCMA), Minnesota. Using public severe weather reports databases and high spatial density rain gauge data, annual frequencies and return-periods are calculated for tornadoes, damaging winds, large hail, and flood-inducing rainfall. The hypothesis that severe thunderstorms and tornadoes are less likely in the central TCMA than in surrounding areas also is examined, and techniques for estimating 100-year rainfall amounts are developed and discussed. This research finds that: (i) storms capable of significant damage somewhere within the TCMA recur annually (sometimes multiple times per year), while storms virtually certain to cause such damage recur every 2-3 years; (ii) though severe weather reports data are not amenable to classical comparative statistical testing, careful treatment of them suggests all types and intensity categories of severe convective weather have been and should continue to be approximately as common in the central TCMA as in surrounding areas; and (iii) applications of Generalized Extreme Value (GEV) statistics and areal analyses of rainfall data lead to significantly larger (25-50%) estimates of 100-year rainfall amounts in the TCMA and parts of Minnesota than those currently published and used for precipitation design. The growth of the TCMA, the popular sentiment that downtown areas somehow deter severe storms and tornadoes, and the prior underestimation of extreme rainfall thresholds for precipitation design, all act to enhance local susceptibility to hazards from severe convective storms.

Blumenfeld, Kenneth A.

267

Pilot Convective Weather Decision Making in En Route Airspace  

NASA Technical Reports Server (NTRS)

The present research investigates characteristics exhibited in pilot convective weather decision making in en route airspace. In a part-task study, pilots performed weather avoidance under various encounter scenarios. Results showed that the margins of safety that pilots maintain from storms are as fluid as deviation decisions themselves.

Wu, Shu-Chieh; Gooding, Cary L.; Shelley, Alexandra E.; Duong, Constance G.; Johnson, Walter W.

2012-01-01

268

Energy and Mass Transport of Magnetospheric Plasmas during the November 2003 Magnetic Storm  

NASA Technical Reports Server (NTRS)

Intensive energy and mass transport from the solar wind across the magnetosphere boundary is a trigger of magnetic storms. The storm on 20-21 November 2003 was elicited by a high-speed solar wind and strong southward component of interplanetary magnetic field. This storm attained a minimum Dst of -422 nT. During the storm, some of the solar wind particles enter the magnetosphere and eventually become part of the ring current. At the same time, the fierce solar wind powers strong outflow of H+ and O+ from the ionosphere, as well as from the plasmasphere. We examine the contribution of plasmas from the solar wind, ionosphere and plasmasphere to the storm-time ring current. Our simulation shows, for this particular storm, ionospheric O+ and solar wind ions are the major sources of the ring current particles. The polar wind and plasmaspheric H+ have only minor impacts. In the storm main phase, the strong penetration of solar wind electric field pushes ions from the geosynchronous orbit to L shells of 2 and below. Ring current is greatly intensified during the earthward transport and produces a large magnetic depression in the surface field. When the convection subsides, the deep penetrating ions experience strong charge exchange loss, causing rapid decay of the ring current and fast initial storm recovery. Our simulation reproduces very well the storm development indicated by the Dst index.

Fok, Mei-Chging; Moore, Thomas

2008-01-01

269

Observations of Convectively Coupled Kelvin Waves forced by Extratropical Wave Activity  

NASA Astrophysics Data System (ADS)

It is well established by observations that deep tropical convection can in certain situations be forced by extratropical Rossby wave activity. Such interactions are a well-known feature of regions of upper level westerly flow, and in particular where westerlies and equatorward wave guiding by the basic state occur at low enough latitudes to interact with tropical and subtropical moisture sources. In these regions convection is commonly initiated ahead of upper level troughs, characteristic of forcing by quasi-geostrophic dynamics. However, recent observational evidence indicates that extratropical wave activity is also associated with equatorial convection even in regions where there is a "critical line" to Rossby wave propagation at upper levels, that is, where the zonal phase speed of the wave is equal to the zonal flow speed. A common manifestation of this type of interaction involves the initiation of convectively coupled Kelvin waves, as well as mixed Rossby-gravity (MRG) waves. These waves are responsible for a large portion of the convective variability within the ITCZ over the Indian, Pacific, and Atlantic sectors, as well as within the Amazon Basin of South America. For example, Kelvin waves originating within the western Pacific ITCZ are often triggered by Rossby wave activity propagating into the Australasian region from the South Indian Ocean extratropics. At other times, Kelvin waves are seen to originate along the eastern slope of the Andes. In the latter case the initial forcing is sometimes linked to a low-level "pressure surge," initiated by wave activity propagating equatorward from the South Pacific storm track. In yet other cases, such as over Africa, the forcing appears to be related to wave activity in the extratropics which is not necessarily propagating into low latitudes, but appears to "project" onto the Kelvin structure, in line with past theoretical and modeling studies. Observational evidence for extratropical forcing of Kelvin and MRG waves will be presented, and the seasonality of these statistical associations will be discussed. Extratropical forcing of equatorial waves appears to be most efficient during the solstice seasons by waves originating within the winter hemisphere and interacting with convection in the summer hemisphere. A companion presentation by J. Biello will examine the theoretical basis for these interactions.

Kiladis, G. N.; Biello, J. A.; Straub, K. H.

2012-12-01

270

The soundproof dynamical core for COSMO model: representation of convective flows.  

NASA Astrophysics Data System (ADS)

Research conducted at Polish Institute of Meteorology and Water Management, National Research Institute, in collaboration with Consortium for Small Scale Modeling (COSMO) are aimed at developing new conservative dynamical core for next generation operational weather prediction model. As the result, a new prototype model was developed with dynamical core based on anelastic set of equation and numerics adopted from the EULAG model. An employment of EULAG allowed to profit from its desirable conservative properties and numerical robustness confirmed in number of benchmark tests and widely documented in scientific literature. The hybrid model consists of EULAG dynamical core implemented into the software environment of the operational COSMO model and basic COSMO physical parameterizations involving turbulence, friction, radiation, moist processes and surface fluxes (COSMO-EULAG). The tool is capable to compute weather forecast in mountainous area for the horizontal resolution of 0.28 km and with slopes reaching 60 degrees of inclination. The presentation is focused on two current research topics. First, the model and especially its dynamics-physics coupling is examined within idealized framework for representation of convective flows. The study is based on two complementary convection benchmarks of Weisman and Klemp (Mon. Wea. Rev. 110:504, 1982) and Grabowski et al. (Q. J. R. Meteorol. Soc. 132:317, 2006). While the first experiment can be used to examine a life cycle of a single convective storm structure in COSMO-EULAG model, the second experiment allows to evaluate the model representation of statistical properties of daytime convective development over land, involving convection initiation as well as is transition into a deep phase. The study involves also the comparison of COSMO-EULAG results with results of standard compressible COSMO-Runge-Kutta model to test the suitability of the anelastic dynamical core for operational mesoscale high-resolution NWP. Next, the results of a realistic case study of Alpine summer convection simulated by COSMO-EULAG with very high horizontal resolutions ranging from 2.2 to 0.28km are presented. While the simulations, even with highest resolution, do not require any artificial orography smoothing, the influence of such smoothing on simulation results is investigated. The study shows e.g. a comparison of flow, cloud and precipitation structure, and spectral analyses of horizontal wind fields. The Cosmo-Eulag forecast is also compared with available meteorological information.

Wójcik, Damian; Piotrowski, Zbigniew; Rosa, Bogdan; Ziemia?ski, Micha?

2014-05-01

271

Forecasting Dust Storms - Version 2  

NSDL National Science Digital Library

Forecasting Dust Storms Version 2 provides background and operational information about dust storms. The first part of the module describes dust source regions, the life cycle of a dust storm, and the major types of dust storms, particularly those found in the Middle East. The second part presents a process for forecasting dust storms and applies it to a case in the Middle East. Although the process refers to U.S. Department of Defense models and tools, it can easily be adapted to other forecast requirements and data sources. Note that this module is an updated version of the original one published in 2003.

2014-09-14

272

Hurricane Sandy Storm Tide Mapper  

NSDL National Science Digital Library

United States Geological Survey (USGS) provides real-time map-based information from USGS storm tide sensors. The data is reflected on the Hurricane Sandy Tide Mapper. The mapper provides location information, site photos and data for storm tide and inland flooding. In addition, the data from these sensors is used to create models of the precise time the storm-tide arrived, how ocean and inland water levels changed during the storm, the depth of the storm-tide throughout the event, and how long it took for the water to recede.

273

The relationship of storm severity to directionally resolved radio emissions  

NASA Technical Reports Server (NTRS)

The objective was to provide continuous observation of atmospheric electrical activity occurring in association with tropical storms in the Gulf of Mexico. The observations were to include the location of all detected intracloud and cloud-to-ground lightning activity occurring in the storm. To provide synoptic scale coverage, a phase linear interferometer high frequency direction finder (HFDF) system was constructed and developed at Marshall Space Flight Center (MSFC). This was used in concert with the existing HFDF interferometer at the southwest research institute to provide lightning location data through triangulation. Atmospheric electrical events were synchronized through the use of satellite receivers at each site. The intent of the data analysis was to correlate the location of electrical centers of activity with radar and satellite imagry to identify areas of intense convection within the tropical storm system. Analysis of the hurricane Alicia data indicate a center of atmospheric electrical activity associated with the vortex of the storm. The center appears to rotate from the Northern side of the vortex to the Southern side during the period of observation. An analysis of the atmospheric electrical burst rates associated with hurrican Alicia indicates that the electrical activity appears to maximize at the time of greatest storm intensity, i.e., maximum winds and lowest central pressure.

Johnson, R. L.

1986-01-01

274

Oxidant enhancement in martian dust devils and storms: storm electric fields and electron dissociative attachment.  

PubMed

Laboratory studies, numerical simulations, and desert field tests indicate that aeolian dust transport can generate atmospheric electricity via contact electrification or "triboelectricity." In convective structures such as dust devils and dust storms, grain stratification leads to macroscopic charge separations and gives rise to an overall electric dipole moment in the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous numerical simulations indicate that these storm electric fields on Mars can approach the ambient breakdown field strength of approximately 25 kV/m. In terrestrial dust phenomena, potentials ranging from approximately 20 to 160 kV/m have been directly measured. The large electrostatic fields predicted in martian dust devils and storms can energize electrons in the low pressure martian atmosphere to values exceeding the electron dissociative attachment energy of both CO2 and H2O, which results in the formation of the new chemical products CO/O- and OH/H-, respectively. Using a collisional plasma physics model, we present calculations of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with the ambient electric field, with substantial production of dissociative products when fields approach the breakdown value of approximately 25 kV/m. The dissociation of H2O into OH/H- provides a key ingredient for the generation of oxidants; thus electrically charged dust may significantly impact the habitability of Mars. PMID:16805701

Delory, Gregory T; Farrell, William M; Atreya, Sushil K; Renno, Nilton O; Wong, Ah-San; Cummer, Steven A; Sentman, Davis D; Marshall, John R; Rafkin, Scot C R; Catling, David C

2006-06-01

275

THE NOAA HAZARDOUS WEATHER TESTBED: COLLABORATIVE TESTING OF ENSEMBLE AND CONVECTION-ALLOWING WRF MODELS AND SUBSEQUENT  

E-print Network

THE NOAA HAZARDOUS WEATHER TESTBED: COLLABORATIVE TESTING OF ENSEMBLE AND CONVECTION-ALLOWING WRF NOAA's Hazardous Weather Testbed (HWT) is a joint facility managed by the National Severe Storms Laboratory (NSSL), the Storm Prediction Center (SPC), and the NWS Oklahoma City/Norman Weather Forecast

Xue, Ming

276

Dust Storm, Aral Sea  

NASA Technical Reports Server (NTRS)

The Aral Sea has shrunk to less than half its size since 1985. The Aral Sea receives little water (sometimes no water) from the two major rivers that empty into it-the Syr Darya and Amu Darya. Instead, the river water is diverted to support irrigation for the region's extensive cotton fields. Recently, water scarcity has increased due to a prolonged drought in Central Asia. As the Aral Sea recedes, its former sea bed is exposed. The Aral's sea bed is composed of fine sediments-including fertilizers and other agricultural chemicals-that are easily picked up by the region's strong winds, creating thick dust storms. The International Space Station crew observed and recorded a large dust storm blowing eastward from the Aral Sea in late June 2001. This image illustrates the strong coupling between human activities (water diversions and irrigation), and rapidly changing land, sea and atmospheric processes-the winds blow across the

2002-01-01

277

Severe storm electricity  

NASA Technical Reports Server (NTRS)

During FY-85, Researchers conducted a field program and analyzed data. The field program incorporated coordinated measurements made with a NASA U2. Results include the following: (1) ground truth measurements of lightning for comparison with those obtained by the U2; (2) analysis of dual-Doppler radar and dual-VHF lightning mapping data from a supercell storm; (3) analysis of synoptic conditions during three simultaneous storm systems on 13 May 1983 when unusually large numbers of positive cloud-to-ground (+CG) flashes occurred; (4) analysis of extremely low frequency (ELF) wave forms; and (5) an assessment of a cloud -ground strike location system using a combination of mobile laboratory and fixed-base TV video data.

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

1985-01-01

278

Winter Storm Lesson Plan  

NSDL National Science Digital Library

The subject of this lesson is Winter Storms. The length will be approximately 55 minutes (~15 minutes for each of the three websites and ~10 minutes for the students to create their slideshows). The slideshows may be presented the following day if not enough time is available. This lesson is intended for 4th grade and is directed towards Standard 2 of the 4th grade science core curriculum. This project explores factors that help create severe winter weather. An interactive simulation provides hands-on experience, followed by guiding questions and resource exploration. Winter Storms Connection to Standards: Utah Core Curriculum: Science Standard 2 (Students will understand that the elements of weather can be observed, measured, and recorded to make predictions and determine simple weather patterns.) NETS-T: 1. Facilitate and Inspire Student Learning and Creativity - Students will be using websites and situations that ...

Tasia S.

2010-09-23

279

Severe storm electricity  

NASA Technical Reports Server (NTRS)

Successful ground truth support of U-2 overflights was been accomplished. Data have been reduced for 4 June 1984 and some of the results have been integrated into some of MSFC's efforts. Staccato lightning (multiply branched, single stroke flash with no continuing current) is prevalent within the rainfree region around the main storm updraft and this is believed to be important, i.e., staccato flashes might be an important indicator of severe storm electrification. Results from data analysis from two stations appear to indicate that charge center heights can be estimated from a combination of intercept data with data from the fixed laboratory at NSSL. An excellent data base has been provided for determining the sight errors and efficiency of NSSL's LLP system. Cloud structures, observable in a low radar reflectivity region and on a scale smaller than is currently resolved by radar, which appear to be related to electrical activity are studied.

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

1984-01-01

280

Evolving dominant charge structures during upscale storm growth in West Texas on 4 June 2012  

NASA Astrophysics Data System (ADS)

The Deep Convective Cloud Chemistry (DC3) field campaign occurred from 15 May and 30 June 2012 with a primary goal of understanding the source of oxides of nitrogen (NOx) in the upper atmosphere due to lightning. In order to better understand this effect, it is necessary to better understand how the local environment can impact the polarity of the lightning in a storm. If polarity changes are driven by changes in electrification mechanisms, changes to the vertical distribution of the lightning channels and NOx source may result. One of the regions participating in DC3 extended from west Texas into central Oklahoma, where an arrangement of three Lightning Mapping Arrays (LMA) allowed for continuous analysis of electrification processes as storms moved across the region and through different local environments. On 4 June 2012 isolated storms initiated within range of the West Texas LMA and generated a mesoscale convective system, part of which dissipated over the West Texas LMA and Southwest Oklahoma LMA domains overnight. Initial storm cells developed within a relatively dry mid-level environment and were observed to contain a mid-level positive charge. However, later storm cells, both further east in deeper moisture and within areas that had previously been moistened by convection, were primarily observed to contain a mid-level negative charge. This presentation will detail the transition from initial discrete storm cells with mid-level positive charge regions and predominantly -IC flashes, to increased cellular coverage with a mixture of charge structures, to longer-lived multicellular clusters dominated by mid-level negative charge and +ICs at upper levels in the storm. These charge structures will be compared to proposed controls on storm electrification, including moisture variability in the mid-troposphere and its relationship to depletion of cloud liquid water.

Sullivan, V. C.; Bruning, E. C.; MacGorman, D. R.; Krehbiel, P. R.; Rison, W.; Edens, H. E.

2013-12-01

281

Defining Coastal Storm and Quantifying Storms Applying Coastal Storm Impulse Parameter  

NASA Astrophysics Data System (ADS)

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.

Mahmoudpour, Nader

2014-05-01

282

Ice Storm Supercomputer  

ScienceCinema

"A new Idaho National Laboratory supercomputer is helping scientists create more realistic simulations of nuclear fuel. Dubbed 'Ice Storm,' this 2048-processor machine allows researchers to model and predict the complex physics behind nuclear reactor behavior. And with a new visualization lab, the team can see the results of its simulations on the big screen." For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

None

2013-05-28

283

Tropical Severe Local Storms  

NSDL National Science Digital Library

The module provides a brief overview of severe local storms in the tropics. Basic ingredients for thunderstorms and assessment of thunderstorm potential from soundings are described. Then properties and hazards of ordinary thunderstorms, multicellular thunderstorms, supercells are reviewed. Conditions conducive to supercell formation in the tropics are examined along with methods of identifying them in radar and satellite images. Supercell and non-supercell tornado properties and formation are described. Finally, tornadoes, waterspouts, and dust devils properties are compared.

COMET

2013-01-09

284

Investigating Magnetic Storms  

NSDL National Science Digital Library

In this activity, students use an internet archive of data on the Earth's magnetic field to study the frequency of magnetic storms of different intensities during the year, and during the solar sunspot cycle. The archive contains values of the Kp scale, an index of how disturbed the Earth's magnetic field was, on average, over each three-hour period of the day. They will select their data, construct a bar graph with it, and answer questions on what their data reveals.

Sten Odenwald

285

3D Simulations of methane convective storms on Titan's atmosphere  

Microsoft Academic Search

The arrival of the Cassini\\/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a

R. Hueso; A. Sánchez-Lavega

2005-01-01

286

METEOR - an artificial intelligence system for convective storm forecasting  

SciTech Connect

An AI system called METEOR, which uses the meteorologist's heuristics, strategies, and statistical tools to forecast severe hailstorms in Alberta, is described, emphasizing the information and knowledge that METEOR uses to mimic the forecasting procedure of an expert meteorologist. METEOR is then discussed as an AI system, emphasizing the ways in which it is qualitatively different from algorithmic or statistical approaches to prediction. Some features of METEOR's design and the AI techniques for representing meteorological knowledge and for reasoning and inference are presented. Finally, some observations on designing and implementing intelligent consultants for meteorological applications are made. 7 references.

Elio, R.; De haan, J.; Strong, G.S.

1987-03-01

287

Catastrophic storms, el nino, and patch stability in a southern california kelp community.  

PubMed

Strong winter storms in southern California destroyed most of the canopy ofthe giant kelp Macrocystis pyrifera but not the patches of understory kelps in the Point Loma kelp forest near San Diego. Subsequent massive recruitment of Macrocystis juveniles and adults that survived the storms had low survival in the summer during the California El Niño of 1983. The combined disturbance may have long-lasting structural consequences for this community because, once established, the understory patches can resist invasion by Macrocystis. PMID:17734914

Dayton, P K; Tegner, M J

1984-04-20

288

Heavier summer downpours with climate change revealed by weather forecast resolution model  

NASA Astrophysics Data System (ADS)

The intensification of precipitation extremes with climate change is of key importance to society as a result of the large impact through flooding. Observations show that heavy rainfall is increasing on daily timescales in many regions, but how changes will manifest themselves on sub-daily timescales remains highly uncertain. Here we perform the first climate change experiments with a very high resolution (1.5 km grid spacing) model more typically used for weather forecasting, in this instance for a region of the UK. The model simulates realistic hourly rainfall characteristics, including extremes, unlike coarser resolution climate models, giving us confidence in its ability to project future changes at this timescale. We find the 1.5 km model shows increases in hourly rainfall intensities in winter, consistent with projections from a coarser 12 km resolution model and previous studies at the daily timescale. However, the 1.5 km model also shows a future intensification of short-duration rain in summer, with significantly more events exceeding the high thresholds indicative of serious flash flooding. We conclude that accurate representation of the local storm dynamics is an essential requirement for predicting changes to convective extremes; when included we find for the model here that summer downpours intensify with warming.

Kendon, Elizabeth J.; Roberts, Nigel M.; Fowler, Hayley J.; Roberts, Malcolm J.; Chan, Steven C.; Senior, Catherine A.

2014-07-01

289

ARkStorm: A West Coast Storm Scenario  

Microsoft Academic Search

The United Stated Geological Survey (USGS) Multi-Hazards Demonstration Project (MHDP) is preparing a new emergency-preparedness scenario, called ARkStorm, to address massive U.S. West Coast storms analogous to those that devastated California in 1861-62. Storms of this magnitude are projected to become more frequent and intense as a result of climate change. The MHDP has assembled experts from the National Oceanic

D. A. Cox; L. M. Jones; F. M. Ralph; M. D. Dettinger; K. Porter; S. C. Perry; P. L. Barnard; D. Hoover; C. J. Wills; J. D. Stock; W. Croyle; J. C. Ferris; G. S. Plumlee; C. N. Alpers; M. Miller; A. Wein; A. Rose; J. Done; K. Topping

2009-01-01

290

Convective heater  

DOEpatents

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation. 14 figs.

Thorogood, R.M.

1983-12-27

291

Convective heater  

DOEpatents

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Thorogood, Robert M. (Macungie, PA)

1986-01-01

292

Chasing Storms: Storm Photo Gallery and Case Study Page  

NSDL National Science Digital Library

John Monteverdi created this website to educate and entertain visitors in the science of storm chasing. Online storm journals for Spring Storm Chases from 1994 to the present take visitors through the life of a storm chaser. Throughout his discussions, the author provides weather charts and satellite images to assist visitors with the weather-related concepts. The site contains countless pictures of tornadoes and the destruction they leave behind. Although some of the amazing images take a few minutes to download, visitors will find that it is worth the wait.

Monteverdi, John P.

293

Extreme convection in subtropical South America: TRMM observations and high-resolution modeling  

NASA Astrophysics Data System (ADS)

Extreme convection tends to form in the vicinity of mountain ranges, and the Andes in subtropical South America help spawn some of the most intense convection in the world. Measurements from the TRMM satellite have allowed for detailed analysis of extreme weather patterns in remote regions of the world, such as subtropical South America. An investigation of the most intense storms for 11 years of TRMM Precipitation Radar (PR) data has shown a tendency for squall lines to initiate and develop in this region. The synoptic environment and mechanisms leading to extreme convection and MCSs in subtropical South America are similar to those found in other regions of the world, including the United States. The mesoscale organizational structure of storms in subtropical South America and the U.S. are markedly similar. However, the topographical influence on the convective initiation and maintenance of the MCSs is unique to South America, where the Andes and related topography focus deep convection initiation in a narrow region. In a previous study, we examined the storm evolution by making use of the time continuity of the GOES infrared satellite data and NCEP/NCAR reanalysis. However, information about the underlying dynamics could not be determined from the data alone. Therefore, we have conducted numerical simulations with the NCAR Weather Research and Forecasting (WRF) Model to extend the analysis and provide an objective dynamical evaluation of storm initiation mechanisms, which include a capping inversion in the lee of the Andes, orographic triggering of the convection, and downstream organization into mesoscale storm systems. We simulated two representative cases with triple-nested domains. The simulated mesoscale systems closely resemble the storm structures seen by the TRMM satellite as well as the overall shape and character of the storms shown in the GOES satellite data. Results from these simulations will be presented at the conference including the role of small scale topographic features, subsidence in the lee of the Andes, and sensitivity to model microphysics.

Rasmussen, K. L.; Houze, R.; Kumar, A.

2012-12-01

294

INTRODUCTION TO STORM SURGE Introduction to  

E-print Network

of storm surge. Too many exceptions to fit the scale: · Hurricane Katrina, a category 3 at landfall SURGE 3 STORM SURGE: BEFORE AND AFTER Before Hurricane Katrina After Hurricane Katrina Images courtesyINTRODUCTION TO STORM SURGE Introduction to Storm Surge National Hurricane Center Storm Surge Unit

295

Convective cell development and propagation in a mesoscale convective complex  

NASA Technical Reports Server (NTRS)

A case study was made of the mesoscale convective complex (MCC) which occurred over southern Oklahoma and northern Texas on 27 May 1981. This storm moved in an eastsoutheasterly direction and during much of its lifetime was observable by radars at Oklahoma City, Ok. and Stephenville, Tx. It was found that the direction of cell (VIP level 3 or more reflectivity) propagation was somewhat erratic but approximately the same as the system (VIP level 1 reflectivity) movement and the ambient wind. New cells developed along and behind the gust front make it appear that once the MCC is initiated, a synergistic relationship exists between the gust front and the MCC. The relationship between rainfall patterns and amounts and the infrared (IR) temperature field in the satellite imagery were examined. The 210 K isotherm of GOES IR imagery was found to encompass the rain area of the storm. The heaviest rainfall was in the vicinity of the VIP level 3 cells and mostly contained within the 205 K isotherm of GOES IR imagery.

Ahn, Yoo-Shin; Brundidge, Kenneth C.

1987-01-01

296

Role of wetlands in attenuation of storm surges using coastal circulation model (ADCIRC), Chesapeake Bay region  

NASA Astrophysics Data System (ADS)

The Chesapeake Bay, Virginia is subject to storm surge from extreme weather events nearly year-round; from tropical storms and hurricanes during the summer and fall, (e.g., hurricanes Isabel [2003] and Sandy [2012]), and from nor'easters during the winter (e.g., winter storms Nemo and Saturn [2013]). Coastal wetlands can deliver acute fortification against incoming hurricane storm surges. Coastal wetlands and vegetation shape the hydrodynamics of storm surge events by retaining water and slowing the propagation of storm surge, acting as a natural barrier to flooding. Consequently, a precise scheme to quantify the effect of wetlands on coastal surge levels was also prerequisite. Two wetland sites were chosen in the Chesapeake Bay region for detailed cataloging of vegetation characteristics, including: height, stem diameter, and density. A framework was developed combining these wetlands characterizations with numerical simulations. Storms surges were calculated using Coastal circulation model (ADCIRC) coupled to a wave model (SWAN) forced by an asymmetric hurricane vortex model using an unstructured mesh (comprised of 1.8 million nodes) under a High Performance Computing environment. The Hurricane Boundary Layer (HBL) model was used to compute wind and pressure fields for historical tropical storms and for all of the synthetic storms. Wetlands were characterized in the coupled numerical models by bathymetric and frictional resistance. Multiple model simulations were performed using historical hurricane data and hypothetical storms to compare the predicted storm surge inundation resulting from various levels of wetlands expansion or reduction. The results of these simulations demonstrate the efficacy of wetlands in storm surge attenuation and also the outcome will scientifically support planning of wetlands restoration projects with multi-objective benefits for society.

Deb, Mithun; Ferreira, Celso; Lawler, Seth

2014-05-01

297

Empirical STORM-E Model. [I. Theoretical and Observational Basis  

NASA Technical Reports Server (NTRS)

Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3 lm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 lm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 lm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3 lm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented

Mertens, Christopher J.; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin G.; Russell, James M., III

2013-01-01

298

Storm Tracks Across Eastern Canada  

NASA Astrophysics Data System (ADS)

The global storm tracks patterns across the Northern Hemisphere are well documented, but their regional impact on populations has yet to be characterized, as very few studies took a local perspective on storm tracks. In this study, a Lagrangian tracking algorithm is applied to the 850 hPa relative vorticity field to characterize extratropical storm tracks that pass through major cities in Canada. Storm tracks are first classified in reference to the metropolitan cities that they impact, such as Toronto, Montreal, Halifax and St-John's. They are then subjected to several analyses, including but not limited to the identification of main development regions, typical tracks, mean growth rate, intensity and typical regions of decay. We found that the preferential development regions are the lee of the Rockies, the Great Lakes and the Western Atlantic. The collection of storm tracks across each city is composed of storms developing not from a single development region, but from several. Results show that the storm track variability at a city is dominated by the storm track variability of its predominant development region. Among others, we found that the ensembles of storms crossing East coast cities (Halifax, St-John's) are dominated by Atlantic storms that are most frequent during the winter. Storms passing through Montreal and Toronto travel primarily from the Great Lakes and the mid-latitude Rockies. In eastern Canada, storms from the southernmost part of the Rockies are much less frequent, but this development region is the main source of extreme storms, and is thus important in terms of impacts on metropolitan areas. The relationship between storm tracks and modes of atmospheric variability are also examined with an emphasis on the El Nino Southern Oscillation (ENSO) and Northern Annular Mode (NAM). We found that teleconnection shifts storm tracks differently in different development regions. The anomalous storm track densities are presented, as well as their direct impact on specific metropolitan areas. Results show that the combination of these shifts impact cities differently according to their geographic location.

Plante, Mathieu; Son, Seok-Woo; Gyakum, John; Kevin, Grise

2013-04-01

299

Summer Modification  

NASA Technical Reports Server (NTRS)

5 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the outer edge of the south polar residual cap of Mars during southern summer. The variability in brightness across the image would not be as apparent had the data been acquired during late winter or spring, owing to the presence of seasonally deposited, carbon dioxide frost. Over the spring and into early summer, the seasonal carbon dioxide is removed through sublimation, and then the thicker, older accumulations of carbon dioxide -- deposited hundreds or thousands of years ago -- erodes. As this occurs, some surfaces become darker, either because they are roughened by erosion, contain dark material such as mineral dust, or both.

Location near: 86.9oS, 111.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2006-01-01

300

Polar Summer  

NASA Technical Reports Server (NTRS)

6 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows south polar mesas composed largely of solid carbon dioxide separated by generally circular depressions. The arcuate scarps, which delineate the mesas, retreat approximately 3 meters per Mars year (two Earth years), owing to sublimation which occurs primarily during the martian summer months.

Location near: 86.9oS, 340.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2006-01-01

301

Structure of the Highly Sheared Tropical Storm Chantal During CAMEX-4  

NASA Technical Reports Server (NTRS)

NASA's 4th Convection and Moisture Experiment (CAMEX-4) focused on Atlantic hurricanes during the 2001 hurricane season and it involved both NASA and NOAA participation. The NASA ER-2 and DC-8 aircraft were instrumented with unique remote sensing instruments to help increase the overall understanding of hurricanes. This paper is concerned about one of the storms studied, Tropical Storm Chantal, that was a weak storm which failed to intense into a hurricane. One of the practical questions of high importance is why some tropical stoins intensify into hurricanes, and others remain weak or die altogether. The magnitude of the difference between the horizontal winds at lower levels and upper altitudes in a tropical storm, i.e., the wind shear, is one important quantity that can affect the intensification of a tropical storm. Strong shear as was present during Tropical Storm Chantal s lifetime and it was detrimental to its intensification. The paper presents an analysis of unique aircraft observations collected from Chantal including an on-board radar, radiometers, dropsondes, and flight level measurements. These measurements have enabled us to examine the internal structure of the winds and thermal structure of Chantal. Most of the previous studies have involved intense hurricanes that overcame the effects of shear and this work has provided new insights into what prevents a weaker storm from intensifying. The storm had extremely intense thunderstorms and rainfall, yet its main circulation was confined to low levels of the atmosphere. Chantal's thermal structure was not configured properly for the storm to intensify. It is most typical that huricanes have a warm core structure where warm temperatures in upper levels of a storm s circulation help intensify surface winds and lower its central pressure. Chantal had two weaker warm layers instead of a well-defined warm core. These layers have been related to the horizontal and vertical winds and precipitation structure and have helped us learn more about why this storm didn't develop.

Heymsfield, G. M.; Halverson, J.; Ritchie, E.; Simpson, Joanne; Molinari, J.; Tian, L.

2004-01-01

302

Autumn Dust Storm  

NASA Technical Reports Server (NTRS)

7 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 3.7 m/pixel (12 ft/pixel) view of a portion of a small dust storm that occurred during early southern autumn in April 2004. The image is located on the floor of a crater near 57.8oS, 271.0oW. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.

2004-01-01

303

Current understanding of magnetic storms: Storm-substorm relationships  

Microsoft Academic Search

This paper attempts to summarize the current understanding of the storm\\/substorm relationship by clearing up a considerable amount of controversy and by addressing the question of how solar wind energy is deposited into and is dissipated in the constituent elements that are critical to magnetospheric and ionospheric processes during magnetic storms. (1) Four mechanisms are identified and discussed as the

Y. Kamide; W. Baumjohann; I. A. Daglis; W. D. Gonzalez; M. Grande; J. A. Joselyn; R. L. McPherron; J. L. Phillips; E. G. D. Reeves; G. Rostoker; A. S. Sharma; H. J. Singer; B. T. Tsurutani; V. M. Vasyliunas

1998-01-01

304

Dust Storms: Why Are Dust Storms a Concern  

MedlinePLUS

... Dust storms can take down power lines, cause power failures, damage infrastructure, and harm computers and communications equipment from the buildup of dust. Some intense dust storms are called haboobs, from the Arabic word for “wind.” They are most frequent in the Southwest from ...

305

Evaluating and Understanding Parameterized Convective Processes and their Role in the Development of Mesoscale Precipitation Systems  

NASA Technical Reports Server (NTRS)

Research efforts during the second year have centered on improving the manner in which convective stabilization is achieved in the Penn State/NCAR mesoscale model MM5. Ways of improving this stabilization have been investigated by (1) refining the partitioning between the Kain-Fritsch convective parameterization scheme and the grid scale by introducing a form of moist convective adjustment; (2) using radar data to define locations of subgrid-scale convection during a dynamic initialization period; and (3) parameterizing deep-convective feedbacks as subgrid-scale sources and sinks of mass. These investigations were conducted by simulating a long-lived convectively-generated mesoscale vortex that occurred during 14-18 Jul. 1982 and the 10-11 Jun. 1985 squall line that occurred over the Kansas-Oklahoma region during the PRE-STORM experiment. The long-lived vortex tracked across the central Plains states and was responsible for multiple convective outbreaks during its lifetime.

Fritsch, J. Michael; Kain, John S.

1997-01-01

306

A study of severe storm electricity via storm intercept  

NASA Technical Reports Server (NTRS)

Storm electricity data, radar data, and visual observations were used both to present a case study for a supercell thunderstorm that occurred in the Texas Panhandle on 19 June 1980 and to search for insight into how lightning to ground might be related to storm dynamics in the updraft/downdraft couplet in supercell storms. It was observed that two-thirds of the lightning ground-strike points in the developing and maturing stages of a supercell thunderstorm occurred within the region surrounding the wall cloud (a cloud feature often characteristic of a supercell updraft) and on the southern flank of the precipitation. Electrical activity in the 19 June 1980 storm was atypical in that it was a right-mover. Lightning to ground reached a peak rate of 18/min and intracloud flashes were as frequent as 176/min in the final stages of the storm's life.

Arnold, Roy T.; Horsburgh, Steven D.; Rust, W. David; Burgess, Don

1985-01-01

307

Perturbation growth at the convective scale  

NASA Astrophysics Data System (ADS)

The development of ensemble forecasting techniques specific to the convective scale is now an active area of research. The aims of this study are to identify the physical processes that lead to perturbation growth at the convective scale in response to model state perturbations and determine the sensitivity to the characterisation of the perturbations. The Met Office Unified Model is run for case which is strongly upper-level forced but for which the detailed mesoscale/convective-scale evolution is dependent on smaller-scale processes. This case was observed during Intensive Observing Period 18 (IOP18) of the Convective Storms Initiation Project (CSIP). Potential temperature is perturbed at a specific model level within the boundary layer. The effects on perturbation growth of both the amplitude and typical scale-length of the perturbations are investigated and perturbations are applied either sequentially (every 30 min. throughout the model simulation) or at specific times. The direct effects (within one timestep) of the perturbations are to generate propagating Lamb and acoustic waves and produce generally small changes in cloud parameters and convective instability. In exceptional cases a perturbation at a specific gridpoint leads to switching of the diagnosed boundary-layer type or discontinuous changes in convective instability, through the generation or removal of a convective lid. The indirect effects (during the entire evolution) of the simulations are changes in the intensity and location of precipitation and the cloud-size distribution. Qualitatively different behaviour is found for strong (1K amplitude) and weak (0.01K amplitude) perturbations with sensitivity to the time of day found only for the weaker perturbations. However, the overall perturbation growth (as measured by the root mean square error of the accumulated precipitation) reaches similar values at saturation, regardless of the perturbation characterisation.

Leoncini, G.; Plant, R. S.; Gray, S. L.; Clark, P. A.

2009-04-01

308

Interannual Behavior of Large Regional Dust Storms  

NASA Astrophysics Data System (ADS)

We examine large regional dust storms in MCS and TES retrieved temperature profiles. There is significant repeatability with three regional storms (A, B and C) each Mars year. Each type of storm is distinct seasonally and in its behavior.

Kass, D. M.; Kleinboehl, A.; McCleese, D. J.; Schofield, J. T.; Smith, M. D.

2014-07-01

309

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2011-10-01

310

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2010-10-01

311

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2013-10-01

312

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2014 CFR

... 2014-10-01 2014-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2014-10-01

313

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2010-10-01

314

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2014-10-01

315

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2011-10-01

316

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2012-10-01

317

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2011-10-01

318

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2010-10-01

319

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2014-10-01

320

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2014-10-01

321

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2012-10-01

322

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2014 CFR

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2014-10-01

323

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2012-10-01

324

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2010-10-01

325

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2011-10-01

326

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2013-10-01

327

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2013-10-01

328

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2012-10-01

329

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2013 CFR

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2013-10-01

330

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2011 CFR

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2011-10-01

331

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2010 CFR

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2010-10-01

332

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2013 CFR

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2013-10-01

333

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2012 CFR

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2012-10-01

334

Summer Journal.  

ERIC Educational Resources Information Center

This student activity book is intended for junior high or high school students. Originally written to be used in a summer television course, the material can be adapted to a regular class situation. The wide variety of materials are relevant to courses in reading, literature, composition, speech, psychology, and social studies. The book includes…

Evansville-Vanderburgh School Corp., IN.

335

Summer Programs.  

ERIC Educational Resources Information Center

An intensive 6-week summer readiness program held in the Beaver Area School District, Beaver, Pennsylvania, developed linguistic facility among 15 preschool children. Daily activities included discussion, picture study, creative arts, field trips, developing experience charts, and other nonlanguage arts activities. A combined experiential,…

Toussaint, Isabella H.

336

Summer Skies  

ERIC Educational Resources Information Center

During the evening hours of the summer of 2005, there will be numerous opportunities to observe several of the brighter planets as they move along their respective orbits, overtaking and passing one another, performing a planetary dance with the choreography set to orbital speeds. With the exception of Mars, the visible planets will all be in the…

Science Scope, 2005

2005-01-01

337

Summer Camp.  

ERIC Educational Resources Information Center

About 50 participants and 8 supervisors attended the Summer Camp. Visitors were encouraged and parents often came to see what their kids were doing. Before arriving at camp, the students learned how important balancing the supplies was when loading the boats. On the way to camp, students studied the: (1) landmarks so that they could find their way…

Pfisterer, Bill

338

Pilgrim Summer.  

ERIC Educational Resources Information Center

Relates the experiences of a teacher's summer working as an "Englishman" on the "Mayflower" II, focusing on questions asked by tourists such as "Where are the other two ships?" Considering the misperceptions of history demonstrated by both young and old Americans, reflects that perhaps there was no "golden age" of education to which we should try…

Trenouth, Peter

1986-01-01

339

Severe storm electricity  

NASA Technical Reports Server (NTRS)

Severe storms and lightning were measured with a NASA U2 and ground based facilities, both fixed base and mobile. Aspects of this program are reported. The following results are presented: (1) ground truth measurements of lightning for comparison with those obtained by the U2. These measurements include flash type identification, electric field changes, optical waveforms, and ground strike location; (2) simultaneous extremely low frequency (ELF) waveforms for cloud to ground (CG) flashes; (3) the CG strike location system (LLP) using a combination of mobile laboratory and television video data are assessed; (4) continued development of analog-to-digital conversion techniques for processing lightning data from the U2, mobile laboratory, and NSSL sensors; (5) completion of an all azimuth TV system for CG ground truth; (6) a preliminary analysis of both IC and CG lightning in a mesocyclone; and (7) the finding of a bimodal peak in altitude lightning activity in some storms in the Great Plains and on the east coast. In the forms on the Great Plains, there was a distinct class of flash what forms the upper mode of the distribution. These flashes are smaller horizontal extent, but occur more frequently than flashes in the lower mode of the distribution.

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

1984-01-01

340

Outreach Plans for Storm Peak Laboratory  

NASA Astrophysics Data System (ADS)

The Desert Research Institute (DRI) operates a high elevation facility, Storm Peak Laboratory (SPL), located on the west summit of Mt. Werner in the Park Range near Steamboat Springs, Colorado at an elevation 10,500 ft. SPL provides an ideal location for long-term research on the interactions of atmospheric aerosol and gas- phase chemistry with cloud and natural radiation environments. SPL includes an office-type laboratory room for computer and instrumentation setup with outside air ports and cable access to the roof deck, a full kitchen and two bunk rooms with sleeping space for nine persons. We plan to create a unique summer undergraduate education experiences for students of diversity at Storm Peak Laboratory. As stressed by the College Pathways to Science Education Standards [Siebert and McIntosh, 2001], to support changes in K-12 science education transformations must first be made at the college level, including inquiry-oriented opportunities to engage in meaningful research. These workshops will be designed to allow students to experience the excitement of science, increasing their likelihood of pursing careers within the fields of scientific education or research.

Hallar, A. G.; McCubbin, I. B.

2006-12-01

341

Hydromagnetic Theory of Geomagnetic Storms  

Microsoft Academic Search

A hydromagnetic theory is presented which explains the average characteristics of geomagnetic storms. The magnetic storm is caused by a sudden increase in the intensity of the solar wind. Stresses are then set up in the geomagnetic field by the solar plasma impinging upon the geomagnetic field and becoming trapped in it. These stresses, which are propagated to the earth

A. J. Dessler; E. N. Parker

1959-01-01

342

Large scale storm outage management  

Microsoft Academic Search

This paper describes a process for improving information used by electric utilities for managing restoration of distribution facilities damaged by large-scale storms such as large-scale ice storms and hurricanes. The process is realized in the form of a decision support tool that utilizes the model of the distribution circuit layout, the placement of protective and switching devices and the location

David Lubkeman; Danny E. Julian

2004-01-01

343

Overwash induced by storm conditions  

E-print Network

.................................................................................29 3.3.2. Tropical Storm Matthew..................................................................33 3.3.3. Hurricane Katrina ............................................................................34 3.3.4. Hurricane Rita...................................................................32 3.9 The track of tropical storm Matthew, 2004 (NOAA, 2004b). ..............................33 3.10 Overwash fan generated by the swell of hurricane Katrina, 2005........................34 3.11 The track of hurricane Katrina...

Park, Young Hyun

2009-05-15

344

A Storm (Worm) Is Brewing  

Microsoft Academic Search

Skilled hackers have designed a sophisticated type of malware that blends multiple techniques, hides and changes its code, and employs tricks to entice users to implement and spread it. The malware is generally called the Storm worm. This paper introduces the basic information about Storm worm and how we can combat against this attack.

Brad Smith

2008-01-01

345

Adolescent Storm and Stress, Reconsidered.  

ERIC Educational Resources Information Center

Explores G. Hall's (1904) view that adolescence is a period of heightened storm and stress in light of contemporary research, focusing on (1) conflict with parents; (2) mood disruptions; and (3) risk behavior. In all these areas, evidence supports a modified storm-and-stress view that takes into account individual differences and cultural…

Arnett, Jeffrey Jensen

1999-01-01

346

Mars Atmospheric Chemistry in Electrified Dust Devils and Storms  

NASA Technical Reports Server (NTRS)

Laboratory studies, simulations and desert field tests all indicate that aeolian mixing dust can generate electricity via contact electrification or "triboelectricity". In convective structures like dust devils or storms, grain stratification (or charge separation) occurs giving rise to an overall electric dipole moment to the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous simulation studies [1] indicate that this storm electric field on Mars can approach atmospheric breakdown field strength of 20 kV/m. In terrestrial dust devils, coherent dipolar electric fields exceeding 20 kV/m have been measured directly via electric field instrumentation. Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via the electric field to values exceeding the electron dissociative attachment energy of both CO2 and H2O, resulting in the formation of new chemical products CO and O- and OH and H- within the storm. Using a collisional plasma physics model we present a calculation of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with ambient electric field, with substantial production of dissociative products when fields approach breakdown levels of 20-30 kV/m.

Farrell, W. M.; Delory, G. T.; Atreya, S. K.; Wong, A.-S.; Renno, N. O.; Sentmann, D. D.; Marshall, J. G.; Cummer, S. A.; Rafkin, S.; Catling, D.

2005-01-01

347

Record-breaking storm activity on Uranus in 2014  

NASA Astrophysics Data System (ADS)

In spite of an expected decline in convective activity following the 2007 equinox of Uranus, eight sizable storms were detected on the planet with the near-infrared camera NIRC2, coupled to the adaptive optics system, on the 10-m W.M. Keck telescope on UT 5 and 6 August 2014. All storms were on Uranus' northern hemisphere, including the brightest storm ever seen in this planet at 2.2 ?m, reflecting 30% as much light as the rest of the planet at this wavelength. The storm was at a planetocentric latitude of ?15°N and reached altitudes of ?330 mbar, well above the regular uppermost cloud layer (methane-ice) in the atmosphere. A cloud feature at a latitude of 32°N, that was deeper in the atmosphere (near ?2 bar), was later seen by amateur astronomers. We also present images returned from our HST ToO program, that shows both of these cloud features. We further report the first detection of a long-awaited haze over the north polar region.

de Pater, Imke; Sromovsky, L. A.; Fry, P. M.; Hammel, Heidi B.; Baranec, Christoph; Sayanagi, Kunio M.

2015-05-01

348

Martian dust storms as a possible sink of atmospheric methane  

NASA Astrophysics Data System (ADS)

Recent laboratory tests, analog studies and numerical simulations all suggest that Martian dust devils and larger dusty convective storms generate and maintain large-scale electric fields. Such expected E-fields will have the capability to create significant electron drift motion in the collisional gas and to form an extended high energy (u $\\gg$ kT) electron tail in the distribution. We demonstrate herein that these energetic electrons are capable of dissociating any trace CH4 in the ambient atmosphere thereby acting as an atmospheric sink of this important gas. We demonstrate that the methane destruction rate increases by a factor of 1012 as the dust storm E-fields, E, increase from 5 to 25 kV/m, resulting in an apparent decrease in methane stability from ~ 1010 sec to a value of ~1000 seconds. While destruction in dust storms is severe, the overall methane lifetime is expected to decrease only moderately due to recycling of products, heterogeneous effects from localized sinks, etc. We show further evidence that the electrical activity anticipated in Martian dust storms creates a new harsh electro-chemical environment.

Farrell, W. M.; Delory, G. T.; Atreya, S. K.

2006-11-01

349

Record-breaking Storm Activity on Uranus in 2014  

E-print Network

In spite of an expected decline in convective activity following the 2007 equinox of Uranus, eight sizable storms were detected on the planet with the near-infrared camera NIRC2, coupled to the adaptive optics system, on the 10-m W. M. Keck telescope on UT 5 and 6 August 2014. All storms were on Uranus's northern hemisphere, including the brightest storm ever seen in this planet at 2.2 $\\mu$m, reflecting 30% as much light as the rest of the planet at this wavelength. The storm was at a planetocentric latitude of $\\sim$15$^{\\circ}$N and reached altitudes of $\\sim$330 mbar, well above the regular uppermost cloud layer (methane-ice) in the atmosphere. A cloud feature at a latitude of 32$^{\\circ}$N, that was deeper in the atmosphere (near $\\sim$2 bar), was later seen by amateur astronomers. We also present images returned from our HST ToO program, that shows both of these cloud features. We further report the first detection of a long-awaited haze over the north polar region.

de Pater, Imke; Fry, P M; Hammel, Heidi B; Baranec, Christoph; Sayanagi, Kunio

2015-01-01

350

Deep convection in the Sahel : a focus on gust fronts  

NASA Astrophysics Data System (ADS)

Convection in the Sahel presents a diurnal variability that is influenced by deep convection systems like the Mesoscale Convective Systems (MCSs) and isolated storms or smaller convective systems. These smaller systems have drew less attention than the MCSs, even though they also play a role in the water cycle of this region, contribute to the monsoon dynamics, and to set the scales of the surface heterogeneities. During the African Monsoon Multidisciplinary Analysis (AMMA) intensive observation period in 2006, many of these smaller systems have been observed with the Massachusetts Institute of Technology (MIT) radar that was installed in Niamey, Niger. A systematic study of daytime convection observed during the month of July 2006 is carried out based on the MIT radar data and on the complementary observations given by the ARM mobile facility, in order to analyse the processes and mechanisms involved of deep convection initiation. The results highlight a large frequency of occurrence of the density currents, and their importance in the initiation of new convective cells. Based on this observational analysis and on results from Large Eddy Simulation (LES), density currents are specifically studied, with the aim at : (1) evaluating their frequency of occurrence, (2) assessing their ability to trigger new convective cells, (3) analysing the sensitivity of density currents velocity to land surface contrasts, (4) testing a simple model for their parametrization, (5) evaluating the ability of the LES to represent density currents.

Dione, Cheikh; Lothon, Marie; Campistron, Bernard; Sall, Saidou M.; Guichard, Françoise; Badiane, Daouda; Couvreux, Fleur

2014-05-01

351

Thyroid storm: an updated review.  

PubMed

Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition. PMID:23920160

Chiha, Maguy; Samarasinghe, Shanika; Kabaker, Adam S

2015-03-01

352

Methane storms as a driver of Titan's dune orientation  

E-print Network

Titan's equatorial regions are covered by eastward propagating linear dunes. This direction is opposite to mean surface winds simulated by Global Climate Models (GCMs), which are oriented westward at these latitudes, similar to trade winds on Earth. Different hypotheses have been proposed to address this apparent contradiction, involving Saturn's gravitational tides, large scale topography or wind statistics, but none of them can explain a global eastward dune propagation in the equatorial band. Here we analyse the impact of equinoctial tropical methane storms developing in the superrotating atmosphere (i.e. the eastward winds at high altitude) on Titan's dune orientation. Using mesoscale simulations of convective methane clouds with a GCM wind profile featuring superrotation, we show that Titan's storms should produce fast eastward gust fronts above the surface. Such gusts dominate the aeolian transport, allowing dunes to extend eastward. This analysis therefore suggests a coupling between superrotation, tro...

Charnay, Benjamin; Rafkin, Scot; Narteau, Clément; Lebonnois, Sébastien; Rodriguez, Sébastien; Pont, Sylvain Courrech du; Lucas, Antoine

2015-01-01

353

Clouds and Dust Storms  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

354

Winter Storm Activity  

NSDL National Science Digital Library

This project explores factors that help create severe winter weather. An interactive simulation provides hands-on experience, followed by guiding questions and resource exploration. Weather affects our everyday lives. Some days it's sunny and some days its not. The years weather is split up into seasons. 1. What are the four seasons? 2. What kind of weather do you see in the summer? 3. What kind of weather is unique to winter? 4. What ...

Jennifer Haight

2010-02-22

355

ARkStorm: A West Coast Storm Scenario  

NASA Astrophysics Data System (ADS)

The United Stated Geological Survey (USGS) Multi-Hazards Demonstration Project (MHDP) is preparing a new emergency-preparedness scenario, called ARkStorm, to address massive U.S. West Coast storms analogous to those that devastated California in 1861-62. Storms of this magnitude are projected to become more frequent and intense as a result of climate change. The MHDP has assembled experts from the National Oceanic and Atmospheric Administration (NOAA), USGS, Scripps Institute of Oceanography, the State of California, California Geological Survey, the University of Colorado, the National Center for Atmospheric Research, and other organizations to design the large, but scientifically plausible, hypothetical scenario storm that would provide emergency responders, resource managers, and the public a realistic assessment of what is historically possible. The ARkStorm patterns the 1861 - 1862 historical events but uses modern modeling methods and data from large storms in 1969 and 1986. The ARkStorm draws heat and moisture from the tropical Pacific, forming Atmospheric Rivers (ARs) that grow in size, gain speed, and with a ferocity equal to hurricanes, slam into the U.S. West Coast for several weeks. Using sophisticated weather models and expert analysis, precipitation, snowlines, wind, and pressure data the modelers will characterize the resulting floods, landslides, and coastal erosion and inundation. These hazards will then be translated into the infrastructural, environmental, agricultural, social, and economic impacts. Consideration will be given to catastrophic disruptions to water supplies resulting from impacts on groundwater pumping, seawater intrusion, water supply degradation, and land subsidence. Possible climate-change forces that could exacerbate the problems will also be evaluated. In contrast to the recent U.S. East and Gulf Coast hurricanes, only recently have scientific and technological advances documented the ferocity and strength of possible future West Coast storms. A task of ARkStorm is to elevate the visibility of the very real threats to human life, property, and ecosystems posed by extreme storms on the U.S. West Coast. This enhanced visibility will help increase the preparedness of the emergency management community and the public to such storms. ARkStorm is scheduled to be completed by September 2010 and will be the basis of a state-wide emergency response drill, Golden Guardian, led by the California Emergency Management Agency in 2011.

Cox, D. A.; Jones, L. M.; Ralph, F. M.; Dettinger, M. D.; Porter, K.; Perry, S. C.; Barnard, P. L.; Hoover, D.; Wills, C. J.; Stock, J. D.; Croyle, W.; Ferris, J. C.; Plumlee, G. S.; Alpers, C. N.; Miller, M.; Wein, A.; Rose, A.; Done, J.; Topping, K.

2009-12-01

356

Storm Events Database  

NSDL National Science Digital Library

From the National Climatic Data Center comes the Storms Events Database. Events are included from 1993 to the present, but as is stated on the site, the site is usually 90-120 days behind the current month. Users first choose a state and then, if necessary, a county, date, and event type. Results can be limited by tornado type, hail size, wind speed, number of injuries or deaths, and even amount of property or crop damage. The generated report lists all of the events during the time period specified and, when clicked, contain specific information about that event. Although the reports can not be downloaded, this powerful resource can be an helpful addition to a researcher's toolbox.

357

Hurricane: Storm Science  

NSDL National Science Digital Library

The Miami Museum of Science educational Web site provides a fun and interactive page called Hurricane: Storm Science. The main page consists of a clickable illustration that includes a Inside a Hurricane link where kids can learn what hurricanes are, how they form, and how to understand a radar image; see a cutaway picture of a hurricane; and more. The weather instruments page lets students explore and complete activities on wind, moisture, temperature, air pressure, and weather measuring tools. Other interesting areas of the site include how radar tracks hurricanes, an interactive exercise to learn how this is done, and even stories that have been submitted by people who have survived hurricanes and other disasters.

2000-01-01

358

Microphysics, Meteorology, Microwave and Modeling of Mediterranean Storms: The M(sup 5) Problem  

NASA Technical Reports Server (NTRS)

Comprehensive understanding of the microphysical nature of Mediterranean storms requires a combination of in situ meteorological data analysis and radar-passive microwave data analysis, effectively integrated with numerical modeling studies at various scales, particularly from synoptic scale down to mesoscale. The microphysical properties of and their controls on severe storms are intrinsically related to meteorological processes under which storms have evolved, processes which eventually select and control the dominant microphysical properties themselves. Insofar as hazardous Mediterranean storms, highlighted by the September 25-28/1992 Genova flood event, the October 5-7/1998 Friuli flood event, and the October 13-15/2000 Piemonte flood event (all taking place in northern Italy), developing a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution and the heterogeneous nature of precipitation fields within the storm domains. This involves convective development, stratiform transition and decay, orographic lifting, and sloped frontal lifting proc esses. This also involves vertical motions and thermodynamical instabilities governing physical processes that determine details of the liquid/ice water contents, size distributions, and fall rates of the various modes of hydrometeors found within the storm environments. This paper presents detailed 4-dimensional analyses of the microphysical elements of the three severe Mediterranean storms identified above, investigated with the aid of SSM/I and TRMM satellite measurements (and other remote sensing measurements). The analyses are guided by nonhydrostatic mesoscale model simulations at high resolution of the intense rain producing portions of the storm environments. The results emphasize how meteorological controls taking place at the large scale, coupled with localized terrain controls, ultimately determine the most salient features of the bulk microphysical properties of the storms. These results have bearing on precipitation remote sensing from space, and the role of modeling in designing precipitation retrieval algorithms.

Smith, Eric A.; Fiorino, Steven; Mugnai, Alberto; Panegrossi, Giulia; Tripoli, Gregory; Starr, David (Technical Monitor)

2001-01-01

359

Detection of Infrasonic Energy From Tornado-Producing Storms  

NASA Astrophysics Data System (ADS)

There are numerous reports in the literature on the observation of infrasound emitted from tornadic thunderstorms. Most of these observations have been made from sensors that are several hundreds of kilometers from the location of the storm, and "ground truth" about the tornadic activity is not well established. We report here on a campaign carried out during the summer of 2011 in which 50 infrasound microphones (whose approximate frequency response is 0.01-500 Hz) developed at the University of Mississippi were deployed by members of Hyperion Technology Group and their associates as part of an ongoing multi-university program on hazard detection and alert funded by the National Oceanic and Atmospheric Administration (NOAA). In this campaign, our deployment teams were able to deploy sensors along the paths of developing tornadic storms, including sensors that were located between twin F5 tornados near Oklahoma City on May 24, 2011. For this particular deployment we had sensors located a few kilometers from the northern most F5 tornado, and a second array, composed of three linear element arrays, that was optimally northeast of the storm. (A total of 7 tornados touched down in this area during this particular severe weather outbreak.) Substantial meteorological information, including ground truth about tornados (intensity and size as a function of time), and the relative close proximity of the sensors to the storms, provides us with a level of detail not available in previous storms. We will report on our infrasound measurements and analysis (source strength, frequency content as a function of tornadic intensity) from this outbreak as well as data from two other interceptions of tornadic storms, which occurred on the dates of May 30 and June 19, 2001.

Talmadge, C. L.; Waxler, R.; Kleinert, D. E.; Carter, G. E.; Godbold, G.; Harris, D. R.; Williams, C.

2011-12-01

360

The climatology of lightning producing large impulse charge moment changes with an emphasis on mesoscale convective systems  

NASA Astrophysics Data System (ADS)

The use of both total charge moment change (CMC) and impulse charge moment change (iCMC) magnitudes to assess the potential of a cloud-to-ground (CG) lightning stroke to induce a mesospheric sprite has been well described in literature. However, this work has primarily been carried out on a case study basis. To complement these previous case studies, climatologies of regional, seasonal, and diurnal observations of large-iCMC discharges are presented. In this study, large-iCMC discharges for thresholds > 100 and > 300 C km in both positive and negative polarities are analyzed on a seasonal basis using density maps of 2o by 2o resolution across the conterminous U.S. using data from the Charge Moment Change Network (CMCN). Also produced were local solar time diurnal distributions in eight different regions covering the lower 48 states as well as the Atlantic Ocean, including the Gulf Stream. In addition, National Lightning Detection Network (NLDN) cloud-to-ground (CG) flash diurnal distributions were included. The seasonal maps show the predisposition of large positive iCMCs to dominate across the Northern Great Plains, with large negative iCMCs favored in the Southeastern U.S. year-round. During summer, the highest frequency of large positive iCMCs across the Upper Midwest aligns closely with the preferred tracks of nocturnal mesoscale convective systems (MCSs). As iCMC values increase above 300 C km, the maximum shifts eastward of the 100 C km maximum in the Central Plains. The Southwestern U.S. also experiences significant numbers of large-iCMC discharges in summer, presumably due to convection associated with the North American Monsoon (NAM). The Gulf Stream is active year round, with a bias towards more large positive iCMCs in winter. Diurnal distributions in the eight regions support these conclusions, with a nocturnal peak in large-iCMC discharges in the Northern Great Plains and Great Lakes, an early- to mid-afternoon peak in the Intermountain West and the Southeastern US, and a morning peak in large-iCMC discharge activity over the Atlantic Ocean. Large negative iCMCs peak earlier in time than large positive iCMCs, attributed to the maturation of large stratiform charge reservoirs after initial convective development. Results of eight case studies of Northern Great Plains MCSs using the NMQ National Radar Mosaic dataset are also presented. Thresholds described above were used to disseminate iCMC discharges within the MCSs. The radar analysis algorithm on a 5-minute radar volume basis included convective-stratiform partitioning, association of iCMCs and CGs to their respective storms, and statistical analysis on large (100-300 C km) and sprite-class (>300 C km) iCMC-producing storms. Results from these case studies indicated a strong preference of sprite-class iCMCs to be positive and located in stratiform-identified regions. A 2-3 hour delay in the maximum activity of sprite-class iCMCs after the maximum large iCMC activity was noted, and was strongly correlated with the maximum areal coverage of stratiform area. A loose correlation between more frequent sprite-class iCMC production and larger stratiform areas was noted, suggesting that larger stratiform areas are simply more capable, not more likely, to produce high sprite-class iCMC rates. Enhanced maximum convective echo heights corresponded to enhanced sprite-class iCMC activity in stratiform areas, attributed in part to enhanced charge advection from the convective line. In situ charging was also presumed to have a significant role in charge generation leading to sprite-class iCMC discharges in stratiform regions.

Beavis, Nicholas

361

Thromboembolic complications of thyroid storm  

PubMed Central

Summary Thyroid storm is a rare but potentially life-threatening complication of hyperthyroidism. Early recognition and prompt treatment are essential. Atrial fibrillation can occur in up to 40% of patients with thyroid storm. Studies have shown that hyperthyroidism increases the risk of thromboembolic events. There is no consensus with regard to the initiation of anticoagulation for atrial fibrillation in severe thyrotoxicosis. Anticoagulation is not routinely initiated if the risk is low on a CHADS2 score; however, this should be considered in patients with thyroid storm or severe thyrotoxicosis with impending storm irrespective of the CHADS2 risk, as it appears to increase the risk of thromboembolic episodes. Herein, we describe a case of thyroid storm complicated by massive pulmonary embolism. Learning points Diagnosis of thyroid storm is based on clinical findings. Early recognition and prompt treatment could lead to a favourable outcome.Hypercoagulable state is a recognised complication of thyrotoxicosis.Atrial fibrillation is strongly associated with hyperthyroidism and thyroid storm.Anticoagulation should be considered for patients with severe thyrotoxicosis and atrial fibrillation irrespective of the CHADS2 score.Patients with severe thyrotoxicosis and clinical evidence of thrombosis should be immediately anticoagulated until hyperthyroidism is under control. PMID:24683480

Min, T; Benjamin, S; Cozma, L

2014-01-01

362

Late-summer inflitration as affected by cropping and grazing management of winter-wheat pastures.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Agricultural practices that incorporate grazed winter wheat and associated summer management are vital to the rural economy of the southern Great Plains. In regions where high intensity, late summer storms prevail, limited information exists about the impact of these practices, including chemical fa...

363

Colorful Convection Currents  

NSDL National Science Digital Library

In this activity, students create artifical convection currents using hot and cold water, food coloring, and bottles. A materials list, instructions, and a brief explanation of the convection phenomenon are included.

364

Mantle Convection Modeling  

NSDL National Science Digital Library

This research page provides links to two animations of modeled mantle convection, showing the progression of convection over millions of years. There are also links to other work and publications by the author.

Yarden Livnat

365

Prediction and Identification of Flash Flood Storms in Colorado. Part I: Attributes of Environment and Storm Evolution  

NASA Astrophysics Data System (ADS)

Heavy rainfall and hail frequently occur in association with intense, summertime convective storms that form along the foothills and eastern plains of the Colorado Rocky Mountains. Heavy rainfall amounts over localized regions can result in flash flooding in mountain communities and in the dense urban areas along the Front Range, disrupting traffic, causing damage to property and in extreme events, resulting in loss of life. Various approaches have been taken over the years to provide the best possible estimations of quantitative precipitation (QPE) and nowcasts and short-term forecasts of heavy precipitation (QPN and QPF, respectively) in order to assess the potential for flash floods over the 0-6 hr time period and to accurately model and predict streamflow increases and runoff. Ten Colorado flash flood and hailstorm events that occurred during the period from 2008-2012 are examined in detail in Parts I and II of this study to benchmark our current understanding of the attributes and evolution of flash flood events and determine how to improve our prediction and identification of those storms that are likely to produce heavy rainfall of short duration over very specific regions and basins sensitive to flooding. In Part I of this study, we utilize instrumentation available from the Front Range Observational Network Testbed (FRONT) located along the Colorado Front Range. This testbed includes 5 dual-polarimetric Doppler S-band radars and a variety of operational and experimental surface, upper air, and satellite observing systems. These detailed observations provide high resolution observations of wind, temperature, moisture, stability, precipitation rate and accumulation. The events are characterized by environments with relatively high moisture content for the area, both in the boundary layer and at mid-levels and conditionally unstable atmospheres either over the plains or over the mountains, or both. Boundary layer and steering level winds were generally between 2.5 - 15 m/s (5-30 kts), so storms were either semi-stationary or not moving particularly fast. Numerous storms formed on these days, but the heaviest rainfall and flash flood resulted from merging storms, back-building storms, and the continual re-initiation of new storms over the same elevated terrain locations during the afternoon period. The collision of convergence boundaries over the plains and the enhancement of existing storms by convergence boundary passage resulted in the formation of large, semi-stationary storms that proceeded to rain heavily over the Denver urban area, and caused one fatality on one of the days. On another day, the storms that formed all seemed rather similar in character, but the rainfall associated with storms that passed over a recent fire burn area caused flooding in that sensitive land area. Identifying and improving the prediction of those specific storms that will produce the heaviest rainfall or case substantial flooding is challenging. Use of basic extrapolation techniques are not sufficient for prediction of heavy rainfall and flooding events (see Part II). Planned efforts include using the documented attributes of the ten heavy precipitation events to develop improved, location-specific, detection and prediction of heavy precipitation storms.

Roberts, Rita; Wilson, James

2013-04-01

366

Centralized Storm Information System (CSIS)  

NASA Technical Reports Server (NTRS)

A final progress report is presented on the Centralized Storm Information System (CSIS). The primary purpose of the CSIS is to demonstrate and evaluate real time interactive computerized data collection, interpretation and display techniques as applied to severe weather forecasting. CSIS objectives pertaining to improved severe storm forecasting and warning systems are outlined. The positive impact that CSIS has had on the National Severe Storms Forecast Center (NSSFC) is discussed. The benefits of interactive processing systems on the forecasting ability of the NSSFC are described.

Norton, C. C.

1985-01-01

367

Steamship Portland: X-Storms  

NSDL National Science Digital Library

In this lesson students will discover what causes extreme storms such as the Portland Gale of 1898 and the Halloween Nor'easter of 1991. They will identify and explain three factors that contributed to extreme storm conditions in the northwest Atlantic Ocean, off New England, discover how to obtain real-time and historical meteorological data, and compare and contrast extra-tropical cyclones, tropical cyclones, and hybrid storms. This hands-on activity uses on-line data resources and includes: focus questions, learning objectives, teaching time, audio/visual materials needed, background information, learning procedures, evaluations, extensions, as well as resources and student handouts.

Mel Goodwin

368

Stageverslag Open Cell Convection and  

E-print Network

Stageverslag Open Cell Convection and Closed Cell Convection S. Noteboom De Bilt, 2007 #12 or otherwise, without prior permission in writing from the publisher. #12;Open Cell Convection and Closed Cell Convection Saskia Noteboom September 2006 #12;#12;Open Cell Convection and Closed Cell Convection Saskia

Stoffelen, Ad

369

Storm Surge Climatology of the Arctic Marginal Seas  

NASA Astrophysics Data System (ADS)

The shore of the arctic seas are generally of low relief and the combination of waves and high water levels during late summer and fall storms before the development of significant sea-ice cover can be particularly damaging to shorelines. Gravel barrier beaches can be overwashed and eroded while bluffs consisting of unlithified ice-bonded sediment and segregated ice can fail and retreat. Storm surge climatology of the arctic marginal seas is investigated based on observational data and 2-D coupled ice-ocean barotropic model results. Meteorological forcing is calculated based on NCAR/NCEP reanalysis data for 1948-present period. The spatial resolution of the model is 13.89 km. The sea ice conditions (concentration and thickness) are prescribed on the mean monthly basis. The model was calibrated based on the strongest storm surges observed in the Kara, Laptev, East-Siberian, Chukchi and Beaufort Seas. Simulation results are in relatively good agreement with observations of sea level heights and ice drift. Detailed studies showed that the spatial and temporal resolutions of the NCEP/NCAR sea level pressure data (2.5x2.5 degree, 6 hours) are too low and can not reproduce well extreme conditions typical for the relatively small polar cyclones but storm surge event frequency is reproduce very well. The results of this study can be used to aid current and future scenario risk assessments of coastal flooding and costal erosion rates.

Proshutinsky, T.; Proshutinsky, A.; Maslanik, J.; Solomon, S.; Ashik, I.

2002-12-01

370

Convection Simulations A. Nordlund  

E-print Network

Convection Simulations š A. Nordlund Astronomical Observatory, and Theoretical Astrophysics Center State University, East Lansing, MI 48823, U.S.A. Abstract. The abrupt transition from convective convection zone, and properties of the solar p­modes for such direct comparisons between simulations

Stein, Robert

371

SURFACE TENSION DRIVEN CONVECTION  

E-print Network

SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS CONCLUDING REMARKS DYNAMIC TRANSITIONS OF SURFACE TENSION DRIVEN CONVECTION H.Dijkstra T. Sengul S. Wang #12;SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS

Wang, Shouhong

372

Zoned mantle convection  

Microsoft Academic Search

We review the present state of our understanding of mantle convection with respect to geochemical and geophysical evidence and we suggest a model for mantle convection and its evolution over the Earth's history that can reconcile this evidence. Whole-mantle convection, even with material segregated within the Dprimeprime region just above the core-mantle boundary, is incompatible with the budget of argon

Francis Albarède; Rob D. van der Hilst

2002-01-01

373

Severe storm identification with satellite microwave radiometry: An initial investigation with Nimbus-7 SMMR data  

NASA Technical Reports Server (NTRS)

The severe weather characteristics of convective storms as observed by the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) are investigated. Low 37 GHz brightness temperatures (due to scattering of upwelling radiation by precipitation size ice) are related to the occurrence of severe weather (large hail, strong winds or wind damage, tornadoes and funnel clouds) within one hour of the satellite observation time. During 1979 and 1980 over the United States there were 263 storms which had very cold 37 GHz signatures. Of these storms 15% were severe. The SMMR detected hail, wind, and tornadic storms equally well. Critical Success Indices (CSI's) of 0.32, 0.48, and 0.38 are achieved for the thresholding of severe vs. nonsevere low brightness temperature events during 1979, 1980, and the two years combined, respectively. Such scores are comparable to skill scores for early radar detection methods. These results suggest that a future geostationary passive microwave imaging capability at 37 GHz, with sufficient spatial and temporal resolution, would allow the detection of severe convective storms. This capability would provide a useful complement to radar, especially in areas not covered by radar.

Spencer, R. W.; Howland, M. R.

1984-01-01

374

Storm Water Quality Please report any concerns,  

E-print Network

Storm Water Quality Hotline: Please report any concerns, illegal dumping into storm drains, or suspicious activities that may cause environmental harm to the Storm Water Quality Hotline: (831) 4592553) 4594520 http://cleanwater.ucsc.edu Volunteer and intern with the Storm Water Management Program

California at Santa Cruz, University of

375

Storm catastrophes in the United States  

Microsoft Academic Search

A unique historical data set describing the 142 storms each producing losses in excess of $100 million in the United States during the 1950–89 period were analyzed to describe their temporal characteristics. The storms caused $66.2 billion in losses (in 1991 values), 76% of the nation's insured storm losses in this period. These extreme storm catastrophes (SCs) were most prevalent

Joyce M. Changnon

1992-01-01

376

Moisture surges over the Gulf of California and relationships with convective activity  

NASA Astrophysics Data System (ADS)

The North American Monsoon (NAM) is characterized by widespread convective activity and rainfall that is tied to key synoptic and sub-synoptic atmospheric circulation features during summer - from mid-June to September. The core monsoon region, particularly over southwestern United States and around the Gulf of California (GoC), often experiences atmospheric phenomena recognized in the literature as "moisture surges". These moisture surges represent one of the most important sources of rainfall variability in the NAM core region with important implications in the hydroclimate and the water resources management in this semiarid region. Although there are a number of studies relating NAM synoptic-scale conditions with moisture surges and regional rainfall patterns, the interactions between atmospheric phenomena of differing scales still remains under-investigated. The overall objective of this research is to improve the understanding of how smaller-spatial scale atmospheric processes modify the evolution of larger-scale atmospheric conditions over the NAM domain. More specifically, this study aims to determine the relationship between organized mesoscale convective systems (MCSs) and moisture surges, and their associated synoptic forcings in the form of Tropical Easterly Waves (TEW), and eastern Pacific Tropical Storms (TS)/Tropical Cyclones (TC). Similarly, relationships were determined between MCSs and GoC low-level jet (GCLLJ). The present research uses three approaches to determine the links between MCSs and moisture surges. A first component of the research consisted of a detailed analyses of a well-observed moisture surge event that occurred during the North American Monsoon Experiment (NAME-2004). Analyses of aircraft flight-level data, together with other special and routine observations are used to describe the four-dimensional structure of this surge event. Theory and observations indicate that this surge's leading edge resembles a solitary Kelvin wave during its initial stages. MCS convective outflows in the central-GoC were observed to modify northern GoC surge variability and the GCLLJ intensity. The observations highlighted the role of convective activity in modulating the surge and its subsequent evolution. The second component of this research consists of a comprehensive climatological study using historical satellite-estimated MCSs, a multiyear set of surge events, the North American Regional Reanalysis (NARR) products, and microwave scatterometer SeaWinds (QuikSCAT) data. Climatological composites are created based on synoptic timescales features (such as TEWs and TSs/TCs) and intraseasonal variations (30-60 -day Madden-Julian Oscillation (MJO) variability), and are further stratified with respect to mesoscale rainfall variability in the NAMS core region. These results provided new insights into the nature of the GoC moisture flux variability and describe the influence of MCSs in modulating the intensity of moisture surges and the GCLLJ. Further, results revealed the role of MCSs in modulating the diurnal cycle of the GoC low-level circulation during "major surge", "minor surge", and "non-surge" environments. In the third and final component of this research, numerical simulation experiments were performed using the Advance Research Weather and Research Forecasting (ARW V3.0) model to investigate the sensitivity of the model to those physical representations associated with convective processes in surge and non-surge synoptic-scale environments. The approach consisted of simulating features associated with mesoscale convective processes on different synoptic-scale background flows (e.g. during moisture surge and non-surge conditions). In the interest of simplicity, convective outflows, typically resulting from MCS events, were replaced by Cold Bubbles (CBs). Although several assumptions were made to replace the effect of convective activity by those of the CBs, this model configuration permitted evaluating the impact that CBs have on the regional flow during surge a

Mejia-Valencia, John Fredy

377

Lobe cell convection and field-aligned currents poleward of the region 1 current system  

Microsoft Academic Search

We present a case and statistical study of plasma convection in the Northern Hemisphere during summer conditions using electric field, magnetic field, and particle data taken during dawn-dusk directed orbits of the FAST satellite. To our knowledge, this set provides the most comprehensive combination of data as yet presented in support of lobe cell convection from an ionospheric perspective this

S. Eriksson; J. W. Bonnell; L. G. Blomberg; R. E. Ergun; G. T. Marklund; C. W. Carlson

2002-01-01

378

Convectively generated stratospheric gravity waves - The role of mean wind shear  

NASA Technical Reports Server (NTRS)

A two-dimensional numerical simulation of mid-latitude squall lines is used to study the properties of storm-induced stratospheric gravity waves. Owing to the tendency for convective cells to form at the forward edge of a squall line, and then propagate toward the rear, the simulated storms preferentially generate gravity waves that propagate toward the rear of the storm. This anisotropy in gravity wave generation leads to a net vertical transfer of momentum into the stratosphere. Cases with and without stratospheric mean wind shear are compared. In the latter case Doppler shifting of the waves to lower frequencies leads to wave breaking and enhanced wave - mean-flow interaction.

Holton, J. R.; Durran, D.

1993-01-01

379

Analyses of Storm Events in an Adirondack Watershed: a Combined Approach Using Stable Isotopes of Sulfate and Nitrate, Chemistry and Hydrology  

NASA Astrophysics Data System (ADS)

The Archer Creek catchment which is the major inlet to Arbutus Lake at the Huntington Forest in the Adirondack Mountains of New York has been the focus of intensive investigations on hydrological and biogeochemical interactions. We used hydrologic information, solute chemistry and isotopic composition of nitrate (? 15N and ? 18O) and sulfate (? 34S and ? 18O) to evaluate how four summer/early autumn storms affected surface water chemistry after a summer of unusually dry conditions in 2002. Precipitation amounts varied among the storms (Storm 1--Sept. 14-18, 19 mm; Storm 2--Sept. 21-24, 33 mm; Storm 3--Sept. 27-29, 43 mm; Storm 4--Oct. 16-21, 68 mm). With the four storms there was an increase in water yield from 2 to 14%. The first storms resulted in relatively small changes in water chemistry. With progressive storms the changes in water chemistry became more marked with particularly major changes in Cb (sum of base cations), sulfate, nitrate, DOC and pH. The marked changes in chemistry were also reflected in changes in the isotopic composition of sulfate and nitrate. The results indicate that especially for storms 3 and 4 that there was an important solute source most likely attributable to wetlands. The contributions of wetlands was evident due to the large increases in DOC during the storm and evidence of changes in S wetland constituents from both chemical and isotopic information. Although these late summer and fall storms do not play a major role in the overall annual mass balances of solutes for this watershed, these events have distinctive chemistry including depressed pH that have important consequences to watershed processes and the linkage of these processes to climate change.

Mitchell, M. J.; Piatek, K.; Mayer, B.; Kendall, C.; Page, B.; Christopher, S.

2004-05-01

380

Simulating organization of convective cloud fields and interactions with the surface  

E-print Network

! convergence! and! evapotranspiration! or!vapour! condensation! and! deposition,! termed! largeMscale! and! cloud! microphysics!precipitation! efficiency,! respectively;! the! diurnal! nature! of! tropical! oceanic! convection!with!nocturnal!precipitation!peaks... !sea!surface!flux!algorithm!(COARE)!to!the!cloudMresolving!Active!Tracer!HighMresolution!Atmospheric!Model!(ATHAM).!!We!investigate!the!full!diurnal!cycle!of! convection! based! on! the! example! of! the! Hector! storm! over! Tiwi! Islands,! notably...

Hoffmann, Alex

2013-11-12

381

Hurricane and Severe Storm Lenticular  

NSDL National Science Digital Library

This resource is a 4 x 6" lenticular card on NASA's HS3 (Hurricane and Severe Storm Sentinel) aircraft mission, which will overfly tropical storms and hurricanes using NASA's Global Hawk Unmanned Aircraft Systems (UAS) in the Northern Atlantic, Caribbean, and Gulf of Mexico. These flights will improve our understanding of the processes that lead to the development of intense hurricanes. The mission will take place for one-month periods during the 2012, 2013, and 2014 Atlantic Basin hurricane seasons.

382

Hurricane Katrina Storm Surge Reconnaissance  

Microsoft Academic Search

Hurricane Katrina August 23-30, 2005 was one of the costliest and deadliest hurricanes to ever strike the United States, impacting 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

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

2008-01-01

383

Magnetic Storms and Induction Hazards  

NASA Astrophysics Data System (ADS)

Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

Love, Jeffrey J.; Joshua Rigler, E.; Pulkkinen, Antti; Balch, Christopher C.

2014-12-01

384

Magnetic Storms and Solar Activity  

NSDL National Science Digital Library

This is a lesson about the Kp index, a common numerical indicator of magnetic storminess. Learners will access and analyze Kp index plots of magnetic storm strength and determine the relative frequency of stronger versus weaker magnetic storms during periods of higher and lower solar activity. This is the fifteenth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

385

Tropical Storm Sam, Eastern Indian Ocean  

NASA Technical Reports Server (NTRS)

Tropical Storm Sam, Eastern Indian Ocean, exact location unknown, was begining to decay when this photograph was taken. The storm was mostly at sea for its entire duration and had little effect on land. The eye of the storm is still visible with the gyre of swirling clouds rotating clockwise. Winds aloft have begun to shear the tops of the thunderstorms associated with the storm forming a high cirrus cloud cover over the center of the storm.

1990-01-01

386

Assessment of the Pseudo Geostationary Lightning Mapper Products at the Spring Program and Summer Experiment  

NASA Technical Reports Server (NTRS)

Since 2010, the de facto Geostationary Lightning Mapper (GLM) demonstration product has been the Pseudo-Geostationary Lightning Mapper (PGLM) product suite. Originally prepared for the Hazardous Weather Testbed's Spring Program (specifically the Experimental Warning Program) when only four ground-based lightning mapping arrays were available, the effort now spans collaborations with several institutions and eight collaborative networks. For 2013, NASA's Short-term Prediction Research and Transition (SPoRT) Center and NOAA's National Severe Storms Laboratory have worked to collaborate with each network to obtain data in real-time. This has gone into producing the SPoRT variant of the PGLM that was demonstrated in AWIPS II for the 2013 Spring Program. Alongside the PGLM products, the SPoRT / Meteorological Development Laboratory's total lightning tracking tool also was evaluated to assess not just another visualization of future GLM data but how to best extract more information while in the operational environment. Specifically, this tool addressed the leading request by forecasters during evaluations; provide a time series trend of total lightning in real-time. In addition to the Spring Program, SPoRT is providing the PGLM "mosaic" to the Aviation Weather Center (AWC) and Storm Prediction Center. This is the same as what is used at the Hazardous Weather Testbed, but combines all available networks into one display for use at the national centers. This year, the mosaic was evaluated during the AWC's Summer Experiment. An important distinction between this and the Spring Program is that the Summer Experiment focuses on the national center perspective and not at the local forecast office level. Specifically, the Summer Experiment focuses on aviation needs and concerns and brings together operational forecaster, developers, and FAA representatives. This presentation will focus on the evaluation of SPoRT's pseudo-GLM products in these separate test beds. The emphasis will be on how future GLM observations can support operations at both the local and national scale and how the PGLM was used in combination with other lightning data sets. Evaluations for the PGLM were quite favorable with forecasters appreciating the high temporal resolution, the ability to look for rapid increases in lightning activity ahead of severe weather, as well as situational awareness for where convection is firing and for flight routing.

Stano, Geoffrey T.; Calhoun, Kristin K.; Terborg, Amanda M.

2014-01-01

387

Characterization of Convective Systems in Africa in Terms of their Vertical Structure, Electrification and Dynamics  

NASA Astrophysics Data System (ADS)

Mesoscale Convective Systems (MCS) are cloud systems that occur from an ensemble of thunder storms and result in a precipitation that covers a huge contiguous area. They are long-lived storm system having dimensions much larger than an individual storm. Storm systems associated with MCSs over the Africa are tracked for the period July to December 2004 and their properties at different stages of their life are investigated in terms of the vertical reflectivity profile, electrification and dynamics of clouds. The research is facilitated by remote sensing data, which include instantaneous vertical reflectivity fields derived from the TRMM precipitation radar (PR), coincident 1/2-hourly observations of long-range lightning accumulation and Global IR fields. Results show a strong indication of the magnitude and intensity of electrification of a thunderstorm with the stage of its life. More vigorous dynamic conditions with intense electrification are observed during the growing stage of the storm and more or less stable situation uniform distribution of electrification has been distributed to most of the pixels in the storm during its maturity stage and less rainfall and electrification during its decaying stage was a general observation during the period. The vertical reflectivity has been found to be strongly related to the electrification and the stage of the convective life cycle in such away that the reflectivity decrease as the storm matures and decays. A good correlation is observed between the strength of vertical profile of reflectivity, which is a proxy for the ice concentration, and lightning activity.

Tadesse, A.; Anagnostou, E. N.

2007-05-01

388

Eye of the Storm  

NSDL National Science Digital Library

This Website showcases materials from the recently published Simon & Schuster book, Eye of the Storm, which details in vivid watercolors, maps, and journal entries, events from the Civil War as witnessed by Union soldier Private Knox Sneden. The site offers 20 selections from Knox's diaries covering from 1861 to December of 1864, each accompanied by a watercolor or map viewable in two sizes, as well as four Flash presentations of these watercolors based around particular incidents Knox witnessed. The watercolors, while not masterpieces, are fine renderings of characteristic events of the war -- a surprise artillery attack by Rebels against an overconfident and underobservant Union fortification, a surrendering of 10,000 troops, views of battles, sabotage operations, and the like. More than anything, they give a sense of the harsh imprint of war upon an otherwise typically bucolic countryside. Knox's dark lines of soldiers, scarred earth, and flames reflected in slow running rivers show that America's bloodiest war touched not only its people, but its landscape as well.

389

Storm and Clouds  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Yesterday's storm front was moving westward, today's moves eastward. Note the thick cloud cover and beautifully delineated cloud tops.

Image information: VIS instrument. Latitude 72.1, Longitude 308.3 East (51.7 West). 40 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

390

Severe Convection II: Mesoscale Convective Systems  

NSDL National Science Digital Library

Mesoscale convective systems occur worldwide and year-round and are accompanied by the potential for severe weather and flooding. This module describes typical system evolution by examining squall line, bow echo, and MCC characteristics throughout their life cycles. This module has less emphasis on the physical processes controlling MCS structure and evolution than our previously released module, Mesoscale Convective Systems: Squall Lines and Bow Echoes. Instead, this newly updated module includes more material on tropical squall lines, MCC's, and on NWP’s ability to predict convective systems. The module starts with a forecast scenario and concludes with a final exam. Rich graphics, audio narration, and frequent interactions enhance the learning experience.

COMET

2004-09-24

391

New opportunities for the study of Mediterranean storms: the unique capabilities of the Global Hawk aircraft  

NASA Astrophysics Data System (ADS)

Airborne measurements have often played a pivotal role in unravelling critical processess and improving our understanding of the genesis and development of atmospheric disturbances. The availability of innovative aerial platforms now opens new perspectives for the scientific research. One of these platforms is the high altitude long endurance unmanned aircraft Global Hawk (GH), which has unique capabilities in terms of altitude, range of operation, diurnal coverage and flexibility. The GH has an endurance of 31 hrs, a service ceiling of 20000 m and can host a payload of 680 kg. Since it can operate at altitudes close to the boundary conditions of radiative processes, can follow the diurnal variation of aerosol and clouds, can rapidly deploy new instruments with space-time coverage comparable to space-borne ones, it is a platform which is at the same time complementary and competitive with satellites. In fact it combines the short time deployment of aircraft instruments with the global coverage of satellite instruments, while its flight altitude allows better spatial resolution than a satellite and its endurance provides a sufficiently broad overview at a scale relevant for sinoptic meteorology studies. NASA has recently acquired two of such unmanned high altitude aircraft to address a variety of Earth Science objectives, and Italy has a decade long experience of stratospheric in-situ and remote sensing science missions using the Russian M-55 "Geophysica" high altitude piloted aircraft. There is a common interest in a bilateral cooperative program in climate change science using the GH. The collaboration between NASA and Italian scientific institutions may offer the opportunity of deploying the GH over the Mediterranean Basin. The Mediterranean area is of particular interest under many respects. As instance, it would be of great interest to measure, when possible, the 3-dimensional structure and evolution of the aerosol content over the Mediterranean, with particular emphasis on Saharan Air Layer (SAL) events. The frequent occurrence of such events, influencing the development of heavy precipitation systems in the region, as they do for hurricane genesis in the Atlantic west of Africa, promts the study of their impact on microphysical processes during precipitation formation; on lower and upper atmosphere destabilization stemming respectively from the production of a deep mixed layer of near zero potential vorticity and from the associated capping warm layer; and on their radiative impact leading to an enhanced heating of the lower troposphere due to solar radiation absorption by the Saharan dust itself. A different area of investigation would be the study of origin and fate of strong mesoscale disturbances originating in the area during the end of Summer and Fall period. In fact, while most Mediterranean storms have classic baroclinic origins, there are intense mesoscale convective storms which form and evolve into warm core structures deriving their energy directly from the warm sea surface in a fashion similar to tropical cyclones, e.g. hurricanes and typhoons. This type of tropical-like storms have been named Medicanes: understanding their origin and development is of utmost importance in view of their potential changing response in relationship to expected climate changes since it has been speculated that these Mediterranean storms would become more frequent and more vigorous in the near future due to the Mediterranean sea-surface temperature increase that is (probably) already occurring because of global warming. Remote sensing instrumentation (radars, microwave radiometers, lidars) is a primary tool to address this issue from a high-flying platform, to improve the understanding of the thermodynamics, dynamics, and microphysics of clouds, by measuring the evolution of their 3-dimensional thermodynamical, dynamical, and microphysical structures and the 3-dimensional structure and evolution of the aerosol content. The long endurance of the GH will allow the study of cloud systems following their evolution ov

Cairo, F.; Curry, R. E.; Carli, B.

2009-09-01

392

Severe Weather Research at the European Severe Storms Laboratory  

NASA Astrophysics Data System (ADS)

The European Severe Storms Laboratory's (ESSL) aim is to increase understanding of high-impact weather, with a particular focus on phenomena with small spatial and temporal dimensions, such as large hail, convectively-driven severe wind gusts, tornadoes and extreme precipitation.The ESSL performs and supports research activities and contributes to enhancing forecasting and warning capabilities in several ways. First, ESSL supports research by providing quality-controlled point data on severe weather events in the European Severe Weather Database. These data are collected through collaborations with networks of voluntary observers, and National HydroMeteorological Institutes throughout Europe. Second, research carried out at ESSL includes modelling the present and future occurrence of severe weather phenomena. This is done by developing proxies for severe weather events for use with reanalysis and climate model data. Third, at the ESSL Testbed, new products to support forecasting and warning operations are tested and demonstrated. Among these tools are visualizations of NWP ensemble data as well as radar, satellite and lightning detection data. Testbed participants provide feedback to the products and receive training in forecasting severe convective weather. Last, every second year ESSL organizes or co-organizes the European Conferences on Severe Storms.

Groenemeijer, Pieter

2013-04-01

393

A New Perspective on Southern Hemisphere Storm Tracks.  

NASA Astrophysics Data System (ADS)

A detailed view of Southern Hemisphere storm tracks is obtained based on the application of filtered variance and modern feature-tracking techniques to a wide range of 45-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data. It has been checked that the conclusions drawn in this study are valid even if data from only the satellite era are used. The emphasis of the paper is on the winter season, but results for the four seasons are also discussed. Both upper- and lower-tropospheric fields are used. The tracking analysis focuses on systems that last longer than 2 days and are mobile (move more than 1000 km). Many of the results support previous ideas about the storm tracks, but some new insights are also obtained. In the summer there is a rather circular, strong, deep high-latitude storm track. In winter the high-latitude storm track is more asymmetric with a spiral from the Atlantic and Indian Oceans in toward Antarctica and a subtropical jet related lower-latitude storm track over the Pacific, again tending to spiral poleward. At all times of the year, maximum storm activity in the higher-latitude storm track is in the Atlantic and Indian Ocean regions. In the winter upper troposphere, the relative importance of, and interplay between, the subtropical and subpolar storm tracks is discussed. The genesis, lysis, and growth rate of lower-tropospheric winter cyclones together lead to a vivid picture of their behavior that is summarized as a set of overlapping plates, each composed of cyclone life cycles. Systems in each plate appear to feed the genesis in the next plate through downstream development in the upper-troposphere spiral storm track. In the lee of the Andes in South America, there is cyclogenesis associated with the subtropical jet and also, poleward of this, cyclogenesis largely associated with system decay on the upslope and regeneration on the downslope. The genesis and lysis of cyclones and anticyclones have a definite spatial relationship with each other and with the Andes. At 500 hPa, their relative longitudinal positions are consistent with vortex-stretching ideas for simple flow over a large-scale mountain. Cyclonic systems near Antarctica have generally spiraled in from lower latitudes. However, cyclogenesis associated with mobile cyclones occurs around the Antarctic coast with an interesting genesis maximum over the sea ice near 150°E. The South Pacific storm track emerges clearly from the tracking as a coherent deep feature spiraling from Australia to southern South America. A feature of the summer season is the genesis of eastward-moving cyclonic systems near the tropic of Capricorn off Brazil, in the central Pacific and, to a lesser extent, off Madagascar, followed by movement along the southwest flanks of the subtropical anticyclones and contribution to the “convergence zone” cloud bands seen in these regions.

Hoskins, B. J.; Hodges, K. I.

2005-10-01

394

The southern England tornadoes of 30 December 2006: Case study of a tornadic storm in a low CAPE, high shear environment  

NASA Astrophysics Data System (ADS)

On 30 December 2006 an outbreak of tornadoes affected parts of southern and eastern England. The tornadoes occurred as a small, developing depression tracked northeastwards over southern England. Convection developed in the vicinity of the surface cold front as a dry intrusion overspread low level warm sector air from the west. As the tornadic storm moved northeast it progressively moved ahead of the surface cold front and into the warm sector. Although the storm developed within an area of dynamic rainfall, it became increasingly isolated owing to a decrease in coverage and intensity of the surrounding rainfall. After development over central southern England the storm moved northeastwards from Berkshire to Norfolk before moving into the North Sea. Radar reflectivity sequences, a damage survey, and the storm relative locations of tornado damage, suggest that the storm contained a mesocyclone in the early part of its lifetime, which spawned the first two or three tornadoes. The storm echo evolved rapidly as it moved northeast. A bow shaped echo developed between 1530 and 1630 UTC to the south of the tornadic portion of the storm. A larger cyclonic vortex subsequently developed immediately to the north of the bowing echo, which was associated with a large hook shaped echo in radar reflectivity fields. Further tornadic damage occurred close to the tip of this hook. The storm environment was characterised by very large 0-1 km storm relative helicity (over 400 m 2 s - 2 ) and meagre CAPE. Previous studies have shown that the majority of tornado outbreaks in the UK occur in the cool season in similar high shear, low CAPE environments. This case study shows that mesocyclonic tornadic convection may occur in such environments. Further research into cool season tornadic storms is required to determine the dominant type of cool season tornadic convection in the UK and in particular the relative frequency of mesocyclonic and non mesocyclonic tornadoes.

Clark, Matthew R.

395

Estimation of convective mass transfer in solar distillation systems  

Microsoft Academic Search

In this article a thermal model has been developed to determine the convective mass transfer for different Grashof Number range in solar distillatiOn process. The model is based on simple regression analysis. Based on the experimental data obtained from the rigorous outdoor experimentation on passive and active distillation systems for summer climatic conditions, the values of C and n have

Sanjay Kumar; G. N. Tiwari

1996-01-01

396

Tornadoes and severe storms in Spain  

NASA Astrophysics Data System (ADS)

A climatology of tornadoes, waterspouts, and straight winds linked to convection in Spain is presented. The database is divided into three periods according to the main source of information. The three distributions of severe weather are very sensitive to the sources of information, much more than to a possible change in climate. The early period, up to 1825, comprises cases that contain the real facts together with spurious inputs such as religion, myths, beliefs, etc, mixed in an unknown proportion. The period between 1826 and 1975, and the most recent one, up to 2009, enable us to observe geographical and temporal variations as a function of societal changes. The analysis of temporal and geographical distributions allows us to frame the risk in the face of severe storms, and the changes in their perception and management that have come about over time. Although the most recent tornadoes have been weak or strong, the Cádiz tornado of 1671 demonstrates that an extremely rare and violent event can occur in Spain. The large number of victims claimed by this tornado makes it one of the most important in the world.

Gayà, Miquel

2011-06-01

397

2013 Geomagnetic Storm Observations in the Arctic and Antarctic  

NASA Astrophysics Data System (ADS)

During recent 2013 geomagnetic storms, several tongue of ionization (TOI) events have been observed with polar maps of total electron content (TEC) derived from the global network of GNSS receivers. The TOI plasma originates from plasma that has been transported from the mid-latitudes by a feature known as storm enhanced density (SED). The SED plasma separates from the base of the enhanced mid-latitude ionosphere in the afternoon-dusk sector, and forms a plume that carries the plasma westward to the noon-time cusp. The TOI, as observed by GNSS, extends through the dayside cusp, across the polar cap to the night side, in both hemispheres. The TOI is a source of ionospheric irregularities and its distribution across the high latitude ionosphere is controlled by plasma convection. Here, TOI observations are shown using GNSS TEC polar plots overlaid onto SuperDARN HF radar observations of the high-latitude convection pattern. The locations where HF scatter is observed in the presence of TOI plumes are examined. In addition, we overlay observations of scintillation collected by specially equipped GNSS receivers. We explore the similarities between TOI events observed simultaneously in the two hemispheres and examine the time history of the gradients and irregularities. Finally, we report on cases where the position of the SED base stays fixed in latitude and longitude as the earth rotates. This observation is shown below in Figure 1 and holds true in both hemispheres. We correlate these observations to changes in the IMF geomagnetic field. Illustration of fixed position of SED base in March 17, 2013 storm in Northern and Southern Hemispheres.

Coster, A. J.; Thomas, E. G.; Baker, J. B.; Ruohoniemi, J.; Erickson, P. J.; Foster, J. C.

2013-12-01

398

Is Titan's Dune Orientation Controlled by Tropical Methane Storms?  

NASA Astrophysics Data System (ADS)

Titan’s equatorial regions are covered by eastward oriented linear dunes. This direction is opposite to mean surface winds simulated by Global Climate Models (GCMs) at these latitudes, oriented westward as trade winds on Earth [1, 2].Here, we propose that Titan’s dune orientation is actually determined by equinoctial tropical methane storms producing a coupling with superrotation and dune formation. Using meso-scale simulations of convective methane clouds [3, 4] with a GCM wind profile featuring the superrotation [5, 6], we show that Titan’s storms should produce fast eastward gust fronts above the surface. Such gusts dominate the aeolian transport. Using GCM wind roses and analogies with terrestrial dune fields [7], we show that Titan's dune growth occurs eastward under these conditions. Finally, this scenario combining global circulation winds and methane storms can explain other major features of Titan's dunes (i.e. divergence from the equator, size and spacing).References:[1] Lorenz et al.: The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes, Science (2006)[2] Lorenz & Radebaugh: Global pattern of Titan’s dunes: Radar survey from the Cassini prime mission, Geophysical Research Letter (2009)[3] Barth & Rafkin.: TRAMS: A new dynamic cloud model for Titan’s methane clouds, Geophysical Research Letter (2007)[4] Barth & Rafkin.: Convective cloud heights as a diagnostic for methane environment on Titan, Icarus (2010)[5] Charnay & Lebonnois: Two boundary layers in Titan's lower troposphere inferred from a climate model, Nature Geoscience (2012)[6] Lebonnois et al.: Titan global climate model: A new 3-dimensional version of the IPSL Titan GCM, Icarus (2012)[7] Courrech du Pont, Narteau & Gao: Two modes for dune orientation, Geology (2014)

Charnay, Benjamin; Barth, Erika; Rafkin, Scot; Narteau, Clément; Lebonnois, Sébastien; Rodriguez, Sébastien; Courrech du Pont, Sylvain; Lucas, Antoine

2014-11-01

399

Moist convection of Neptune  

SciTech Connect

The authors present a study of methane moist convection on Neptune. They examine the stability conditions to initiate moist convection of methane clouds. Temperature lapse rates that are unstable to moist convection are subadiabatic by a factor of two or more while adiabatic and superadiabatic lapse rates are stable. In the observed Neptune temperature structure, vertical velocities {>=} 40 m s{sup {minus}1} are required to lift moist air above the stable region and initiate moist convection. Alternatively, moist convection could be initiated by air that is slightly drier than its surroundings. Moist convective clouds achieve altitudes up to 100 mb, thereby exceeding the temperature minimum and depositing methane in the Neptune stratosphere. They predict that at least 2000 such clouds penetrate the Neptune stratosphere per hour.

Stoker, C.R.; Toon, O.B. (NASA Ames Research Center, Moffett Field, CA (USA))

1989-08-01

400

The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures  

NASA Technical Reports Server (NTRS)

A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

2005-01-01

401

Yale Summer Session 2014 Summer Faculty Handbook  

E-print Network

;TABLE OF CONTENTS I. FOREWORD 1 II. YALE SUMMER SESSION A. A Brief History of Yale Summer Session 1 B the tremendous institution of higher learning that it is ­ year round. II. YALE SUMMER SESSION A. A BRIEF HISTORY. Credit 5 B. Full-time Enrollment 5 C. Grades 6 D. Final Grades and Transcripts 6 E. Course Changes

402

Yale Summer Session 2013 Summer Faculty Handbook  

E-print Network

;TABLE OF CONTENTS I. FOREWORD 1 II. YALE SUMMER SESSION A. A Brief History of Yale Summer Session 1 B the tremendous institution of higher learning that it is ­ year round. II. YALE SUMMER SESSION A. A BRIEF HISTORY. Credit 5 B. Full-time Enrollment 5 C. Grades 6 D. Final Grades and Transcripts 6 E. Course Changes

403

Meteorological aspects associated with dust storms in the Sistan region, southeastern Iran  

NASA Astrophysics Data System (ADS)

Dust storms are considered natural hazards that seriously affect atmospheric conditions, ecosystems and human health. A key requirement for investigating the dust life cycle is the analysis of the meteorological (synoptic and dynamic) processes that control dust emission, uplift and transport. The present work focuses on examining the synoptic and dynamic meteorological conditions associated with dust-storms in the Sistan region, southeastern Iran during the summer season (June-September) of the years 2001-2012. The dust-storm days (total number of 356) are related to visibility records below 1 km at Zabol meteorological station, located near to the dust source. RegCM4 model simulations indicate that the intense northern Levar wind, the high surface heating and the valley-like characteristics of the region strongly affect the meteorological dynamics and the formation of a low-level jet that are strongly linked with dust exposures. The intra-annual evolution of the dust storms does not seem to be significantly associated with El-Nino Southern Oscillation, despite the fact that most of the dust-storms are related to positive values of Oceanic Nino Index. National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis suggests that the dust storms are associated with low sea-level pressure conditions over the whole south Asia, while at 700 hPa level a trough of low geopotential heights over India along with a ridge over Arabia and central Iran is the common scenario. A significant finding is that the dust storms over Sistan are found to be associated with a pronounced increase of the anticyclone over the Caspian Sea, enhancing the west-to-east pressure gradient and, therefore, the blowing of Levar. Infrared Difference Dust Index values highlight the intensity of the Sistan dust storms, while the SPRINTARS model simulates the dust loading and concentration reasonably well, since the dust storms are usually associated with peaks in model simulations.

Kaskaoutis, D. G.; Rashki, A.; Houssos, E. E.; Mofidi, A.; Goto, D.; Bartzokas, A.; Francois, P.; Legrand, M.

2014-06-01

404

Atmospheric Processes: Convection  

NSDL National Science Digital Library

In this two-part activity, students observe the phenomenon of convection and the fact that air can behave as a fluid like water, only less dense. They should understand that convection currents are found in many places and on many scales, such as huge convection currents in the atmosphere, oceans, and even in the Earth's interior, or as smaller convection currents that can be found in a cup of hot cocoa or a fish tank. Lists of materials, instructions, variations on the experiments, observations, and questions are provided. This activity can be performed as a demonstration by the teacher, or older students can conduct the experiments themselves.

2005-03-10

405

Deep Convective Clouds  

NSDL National Science Digital Library

Convective clouds are clouds that develop vertically appearing like big stacks of clouds. One very common example is cumulonimbus clouds. Convective clouds are commonly connected to stormy weather. Monthly Cloud Coverage for Deep Convective Cloud data can be used to predict patterns in weather. The specific pattern associated with this data is tracking and predicting thunderstorms. In this lesson, the students will take a look at the Monthly Cloud Coverage for Deep Convective Cloud data, and name one month of the year 'Thunderstorm Season' for their continent.

406

Silver iodide seeding impact on the microphysics and dynamics of convective clouds in the high plains  

Microsoft Academic Search

The concept of dynamic seeding is a physically plausible hypothesis but has not yet been confirmed by observations or numerical simulations. To verify the hypothesis of dynamic seeding, a three-dimensional nonhydrostatic cloud model with two-moment bulk microphysics scheme has been used to investigate the effects of silver iodide seeding on cloud microphysics, dynamics and precipitation of convective storms. Eight species

Baojun Chen; Hui Xiao

2010-01-01

407

Relationships between lightning and properties of convective cloud clusters  

NASA Astrophysics Data System (ADS)

Satellite observations of convective system properties and lightning flash rate are used to investigate the ability of potential lightning parameterizations to capture both the dominant land-ocean contrast in lightning occurrence and regional differences between Africa, the Amazon and the islands of the maritime continent. As found in previous studies, the radar storm height is tightly correlated with the lightning flash rate. A roughly second order power-law fit to the mean radar echo top height above the 0°C isotherm is shown to capture both regional and land-ocean contrasts in lightning occurrence and flash rate using a single set of parameters. Recent developments should soon make it possible to implement a parameterization of this kind in global models. Parameterizations based on cloud top height, convective rain rate and convective rain fraction all require the use of separate fits over land and ocean and fail to capture observed differences between continental regions.

Futyan, Joanna M.; Del Genio, Anthony D.

2007-08-01

408

Springtime North Polar Dust Storms  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-321, 12 December 2002

As on the Earth, many severe storms brew in the martian polar regions. Here, temperature contrasts between the cold carbon dioxide ('dry ice') seasonal frost cap and the warm ground adjacent to it--combined with a flow of cool polar air evaporating off the cap--sweeps up dust and funnels it into swirling dust storms along the cap edge. The dust storms shown here were observed during the recent northern spring by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2002. The picture is a mosaic of daily global images from the MOC wide angle cameras. The north polar cap is the bright, frosty surface at the top.

2002-01-01

409

Modeling storm-time electrodynamics of the low-latitude ionosphere–thermosphere system: Can long lasting disturbance electric fields be accounted for?  

Microsoft Academic Search

Storm-time ionospheric disturbance electric fields are studied for two large geomagnetic storms, March 31, 2001 and April 17–18, 2002, by comparing low-latitude observations of ionospheric plasma drifts with results from numerical simulations based on a combination of first-principles models. The simulation machinery combines the Rice convection model (RCM), used to calculate inner magnetospheric electric fields, and the coupled thermosphere ionosphere

Naomi Maruyama; Stanislav Sazykin; Robert W. Spiro; David Anderson; Adela Anghel; Richard A. Wolf; Frank R. Toffoletto; Timothy J. Fuller-Rowell; Mihail V. Codrescu; Arthur D. Richmond; George H. Millward

2007-01-01

410

A coordinated study of a storm system over the South American continent. I. Weather information and quasi-dc stratospheric electric field data  

SciTech Connect

A coordinated campaign conducted in Brazil on 13 December 1989, to study the electrical signals associated with a large storm system over the South American continent is presented. Within the storm, large convective cells developed extending up to the tropopause, as observed from meteorological balloon soundings. The analysis of IR imagery supports the general tendency for lightning strikes to be close to but not exactly beneath the coldest cloud tops. 35 refs.

Pinto, O. Jr.; Pinto, I.R.C.A.; Gin, R.B.B.; Mendes, O. Jr. (INPE, Sao Jose dos Campos (Brazil))

1992-11-01

411

A summary of research on mesoscale energetics of severe storm environments  

NASA Technical Reports Server (NTRS)

The goals of this research were to better understand interactions between areas of intense convection and their surrounding mesoscale environments by using diagnostic budgets of kinetic (KE) and available potential energy (APE). Three cases of intense convection were examined in detail. 1) Atmospheric Variability Experiments (AVE) carried out on 24 to 25 April 1975 were studied. Synoptic scale data at 3 to 6 hour intervals, contained two mesoscale convective complexes (MCCs). Analyses included total KE budgets and budgets of divergent and rotational components of KE. 2) AVE-Severe Environmental Storms and Mesoscale Experiments (SESAME)-4 carried out on 10 to 11 April 1979 were studied. Synotpic and meso alpha-scale data (250 km spacing, 3 hour intervals), contained the Red River Valley tornado outbreak. Analyses included total KE budgets (separate synoptic and mesoscale version), budgets for the divergent and rotational components, and the generation of APE by diabatic processes. 3) AVE-SESAME 5 studies were carried out on 20 to 31 May 1979. Synoptic and meso beta-scale data (75 km spacing, 1 1/2 to 3 hour intervals), contained a small MCC. Analyses include separate KE budgets for the synotic and meso beta-scales and a water vapor budget. Major findings of these investigations are: (1) The synoptic scale storm environment contains energy conversions and transports that are comparable to those of mature midlatitude cyclones. (2) Energetic in the mesoscale storm environment are often an order of magnitude larger than those in an undisturbed region. (3) Mesoscale wind maxima form in the upper troposphere on the poleward sides of convective areas, whereas speeds decrease south of storm regions.

Fuelberg, H. E.

1985-01-01

412

Indian Summer  

SciTech Connect

This paper focuses on preserving and strengthening two resources culturally and socially important to the Shoshone-Bannock Indian Tribe on the Fort Hall Reservation in Idaho; their young people and the Pacific-Northwest Salmon. After learning that salmon were not returning in significant numbers to ancestral fishing waters at headwater spawning sites, tribal youth wanted to know why. As a result, the Indian Summer project was conceived to give Shoshone-Bannock High School students the opportunity to develop hands-on, workable solutions to improve future Indian fishing and help make the river healthy again. The project goals were to increase the number of fry introduced into the streams, teach the Shoshone-Bannock students how to use scientific methodologies, and get students, parents, community members, and Indian and non-Indian mentors excited about learning. The students chose an egg incubation experiment to help increase self-sustaining, natural production of steelhead trout, and formulated and carried out a three step plan to increase the hatch-rate of steelhead trout in Idaho waters. With the help of local companies, governmental agencies, scientists, and mentors students have been able to meet their project goals, and at the same time, have learned how to use scientific methods to solve real life problems, how to return what they have used to the water and land, and how to have fun and enjoy life while learning.

Galindo, E. [Sho-Ban High School, Fort Hall, ID (United States)

1997-08-01

413

National Severe Storms Forecast Center  

NASA Technical Reports Server (NTRS)

The principal mission of the National Severe Storms Forecast Center (NSSFC) is to maintain a continuous watch of weather developments that are capable of producing severe local storms, including tornadoes, and to prepare and issue messages designated as either Weather Outlooks or Tornado or Severe Thunderstorm Watches for dissemination to the public and aviation services. In addition to its assigned responsibility at the national level, the NSSFC is involved in a number of programs at the regional and local levels. Subsequent subsections and paragraphs describe the NSSFC, its users, inputs, outputs, interfaces, capabilities, workload, problem areas, and future plans in more detail.

1977-01-01

414

Multi-Sensor Analysis of Overshooting Tops in Tornadic Storms  

NASA Astrophysics Data System (ADS)

The disastrous 2011 tornado season focused much attention on the ~75% false alarm rate for NWS-issued tornado warnings. Warnings are correctly issued on ~80% of verified tornados, but the false alarm rate has plateaued at near 75%. Any additional clues that may signal tornadogenesis would be of great benefit to the public welfare. We have performed statistical analyses of the structure and time-evolution of convective overshooting tops for tornadic storms occurring in the continental United States since 2006. An amalgam of case studies and theory has long suggested that overshooting tops may often collapse just prior to the onset of tornado touchdown. Our new results suggest that this view is supported by a broad set of new statistical evidence. Our approach to the analysis makes use of a high resolution, multi-sensor data set, and seeks to gather statistics on a large set of storms. Records of 88-D NEXRAD radar Enhanced-Resolution Echo Tops (product available since 2009) have been analyzed for an hour prior to and following touchdown of all EF1 and stronger storms. In addition, a coincidence search has been performed for the NASA A-Train satellite suite and tornadic events since 2006. Although the paths of the polar-orbiting satellites do not aid in analyses of temporal storm-top evolution, Aqua-MODIS, CALIPSO, and Cloud-Sat have provided a detailed structural picture of overshooting tops in tornadic and non-tornadic supercell thunderstorms. 250 m resolution AQUA-MODIS image at 1950Z on 4/27/2011, color-enhanced to emphasize overshooting tops during tornado outbreak.

Magee, N. B.; Goldberg, R.; Hartline, M.

2012-12-01

415

Role of model resolution and microphysical properties in simulating flash flood induce storms  

NASA Astrophysics Data System (ADS)

Flash flood induce storms are mainly of convective nature and develop at small space and short time scales making their predictability a particularly challenging task. The tremendous societal and economical impact of this hazard necessitates the development of accurate forecasting systems in order to advance warnings and mitigate the risk. To be able to develop a forecasting system that can accurately represent flash flood storms, we need to understand the key elements that control the generation and evolution of this type of events. This study examines the effect of topographic representation, model grid resolution and cloud microphysical properties in simulating three major flash flood storms that occurred in Northern Italy. To simulate those heavy precipitation events, the high-resolution integrated atmospheric model RAMS / ICLAMS was used with grid resolutions of 250 m, in order to properly resolve the complex physical processes and convective activity. In addition, a high resolution topography dataset of 3 arcsec from the NASA SRTM mission was implemented in the model. The sensitivity of microphysical properties and aerosol cloud interactions towards convection and precipitation over the area were examined through various model setups and simulations. The specific properties proved to play a significant role in the correct estimation of spatial distribution and quantity of precipitation, as indicated from the comparison of the model outputs with bias adjusted radar data.

Bartsotas, Nikolaos; Solomos, Stavros; Nikolopoulos, Efthymios I.; Anagnostou, Emmanouil; Kallos, George

2013-04-01

416

a Diagnostic Study of Two Summer Depressions Over the Changjiang-Huaihe Valley  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Two summer depressions over the Changjiang-Huaihe Valley are investigated using data obtained from a synoptic observation network over East Asia and objectively analysed by applying a new scheme, which is mainly based on spline function interpolation. Detailed spatial structures and temporal evolution are documented in terms of pressure, temperature, moisture and wind fields. Vertical velocity fields are estimated using two independent methods, namely, the kinematic method and the quasi-geostrophic omega equation with consideration of stable and convective condensational heating. Quasi -Lagrangian budgets are computed for vorticity, kinetic energy, available potential energy, moisture and heat. The dynamic structures of the two depressions are analysed in terms of potential vorticity, moisture-related stabilities and geostrophic frontogenesis. Although their vertical structures and budget relations have some features typical of tropical disturbances, both depressions are closely related to a feeble Mei-yu front in the lower troposphere during their mature stage. Two different structures associated with the lower level frontal zone and a mid-upper layer warm belt are identified and related to the large scale circulation over East Asia. The adiabatic forcing under the quasi-geostrophic approximation is able to determine the general regions of ascent and descent associated with these depressions. On the other hand, the diabatic heating is the primary factor to account for the large magnitude of ascent, especially during the pre-storm and mature stages. Conditional symmetric instability and frontogenesis in the presence of small conditional symmetric stability are possible mechanisms in favour of the maintenance and development of the degressions. Based on these results, a conceptual model of the summer depressions over the Changjiang-Huaihe Valley is proposed.

Dingchen, Hou

1987-09-01

417

The Perfect Storm? By Tom Steele  

E-print Network

life around here. On August 14 a violent storm ripped through the Northwoods. Kemp Station lay directly in its path. The storm left hundreds of snapped, shattered and toppled trees in its wake. The good news

418

ESTIMATING PARAMETERS FOR CHARACTERIZING TIMES BETWEEN STORMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Characterization and estimation of times between storms are needed for stochastic storm simulation, drought studies, etc. An exploratory investigation into practical estimation of two characterization parameters was conducted using regression equations - critical duration (CD, minimum dry time betw...

419

Storm Water Survey Answer Sheet About You  

E-print Network

is not allowed in the storm drains on campus? (Check all that apply) Irrigation water Water flowing from irrigation systems Water flowing from washing vehiclesStorm Water Survey Answer Sheet About You 1. What is your

California at Santa Cruz, University of

420

Summer Studies CALENDAR 2010  

E-print Network

Summer Studies UNIVERSITY CALENDAR 2010 #12;McGill University, 2010 Summer Studies 1 ABOUT About This Calendar Published by: McGill Summer Studies McGill University 688 Sherbrooke Street West, Suite 1029, and changes can be made after this Calendar is published. Please check the Summer Studies website at www

Fabry, Frederic

421

Slithering into Summer  

ERIC Educational Resources Information Center

The summer provides a unique opportunity for children to further their interests in science, especially science in the out-of-doors. Once school is out for the summer, there is seemingly unlimited time, with no strict curriculum guidelines to follow. For students with a passion for the out-of-doors, summer science camps and school-based summer

Scott, Catherine; Matthews, Catherine

2012-01-01

422

Microphysical Contributions to the Latent Heating Structures of Midlatitude and Tropical Storms and Feedbacks to Storm Organization  

NASA Astrophysics Data System (ADS)

Latent heating associated with phase changes is a fundamental cloud process, and is influenced by both the microphysical and dynamical characteristics of the cloud system. As such, the structure of latent heating tends to be a function of the vertical profile, as well as of cloud type. Furthermore, changes to the latent heating can induce significant changes to the intensity of the cloud system, which in turn can have feedbacks on the microphysical processes and precipitation production of such storms. In spite of the importance of latent heating across a broad range of cloud systems, few direct measurements of this field are made routinely on a global basis. Nearly all current large-scale retrieval schemes depend heavily on some form of cloud resolving model simulations. With the development and design of future satellite and radar systems, it is hoped that more direct measurements of latent heat may become possible. However, in the meantime, it appears that one of our most appropriate tools to examine latent heating is cloud resolving models with sophisticated cloud microphysical schemes. The goal of the research to be presented is to examine the variations in the magnitude and distribution of latent heating across a range of different storm types, the role of different microphysical processes in explaining such variations, and the feedbacks between latent heating and dynamics in the organization of such systems. In particular, these characteristics will be examined for extratropical cyclones, squall lines and deep tropical convection. The goal will be achieved by examining a suite of numerical simulations of these storm systems conducted using the Regional Atmospheric Modeling System (RAMS). Recent developments to the model code allow for the evaluation of the contributions made by each microphysical process to the latent heating throughout the model domain. Insights into the importance of different microphysical processes in explaining the vertical and horizontal structures in the latent heating field, as well as the feedbacks to storm organization will be discussed.

van den Heever, S. C.; Saleeby, S. M.; Herbener, S.; Storer, R. L.; Seigel, R. B.; Igel, A. L.; Sheffield, A. M.; McGee, C. J.; Igel, M. R.; Grant, L. D.; Clavner, M.; L'Ecuyer, T.; Berg, W. K.

2012-12-01

423

Assessing the Predictability of Convection using Ensemble Data Assimilation of Simulated Radar Observations in an LETKF system  

NASA Astrophysics Data System (ADS)

This study uses the Local Ensemble Transform Kalman Filter (LETKF) to perform storm-scale Data Assimilation of simulated Doppler radar observations into the non-hydrostatic, convection-permitting COSMO model. In perfect model experiments (OSSEs), it is investigated how the limited predictability of convective storms affects precipitation forecasts. The study compares a fine analysis scheme with small RMS errors to a coarse scheme that allows for errors in position, shape and occurrence of storms in the ensemble. The coarse scheme uses superobservations, a coarser grid for analysis weights, a larger localization radius and larger observation error that allow a broadening of the Gaussian error statistics. Three hour forecasts of convective systems (with typical lifetimes exceeding 6 hours) from the detailed analyses of the fine scheme are found to be advantageous to those of the coarse scheme during the first 1-2 hours, with respect to the predicted storm positions. After 3 hours in the convective regime used here, the forecast quality of the two schemes appears indiscernible, judging by RMSE and verification methods for rain-fields and objects. It is concluded that, for operational assimilation systems, the analysis scheme might not necessarily need to be detailed to the grid scale of the model. Depending on the forecast lead time, and on the presence of orographic or synoptic forcing that enhance the predictability of storm occurrences, analyses from a coarser scheme might suffice.

Lange, Heiner; Craig, George

2014-05-01

424

Pie-Pan Convection  

NSDL National Science Digital Library

In this activity, students observe fluid motion and the formation of convection cells as a solution of soap and water is heated. This procedure can be performed as a demonstration by the teacher, or older students can conduct the experiment themselves. A list of materials, instructions, and a description of the convective process are included.

2005-03-10