Data requirements in support of the marine weather service program

NASA Technical Reports Server (NTRS)

Travers, J.; Mccaslin, R. W.; Mull, M.

1972-01-01

Data support activities for the Marine Weather Service Program are outlined. Forecasts, cover anomolous water levels, including sea and swell, surface and breakers, and storm surge. Advisories are also provided for sea ice on the Great Lake and Cook inlet in winter, and in the Bering, Chukchi, and Beaufort Seas in summer. Attempts were made to deal with ocean currents in the Gulf Stream, areas of upwelling, and thermal structure at least down through the mixed layer.

Characterization of Sea Lamprey stream entry using dual‐frequency identification sonar

USGS Publications Warehouse

McCain, Erin L.; Johnson, Nicholas; Hrodey, Peter J.; Pangle, Kevin L.

2018-01-01

Effective methods to control invasive Sea Lampreys Petromyzon marinus in the Laurentian Great Lakes often rely on knowledge of the timing of the Sea Lamprey spawning migration, which has previously been characterized using data gathered from traps. Most assessment traps are located many kilometers upstream from the river mouth, so less is known about when Sea Lampreys enter spawning streams and which environmental cues trigger their transition from lakes to rivers. To decide how to develop barriers and traps that target Sea Lampreys when they enter a stream, the stream entry of Sea Lampreys into a Lake Huron tributary during 2 years was assessed using dual‐frequency identification sonar (DIDSON). Sea Lampreys entered the stream in low densities when temperatures first reached 4°C, which was up to 6 weeks and a mean of 4 weeks earlier than when they were first captured in traps located upstream. The probability of stream entry was significantly affected by stream temperature and discharge, and stream entry timing peaked when stream temperatures rose to 12°C and discharge was high. Examination of the entry at a finer temporal resolution (i.e., minutes) indicated that Sea Lampreys did not exhibit social behavior (e.g., shoaling) during stream entry. Our findings indicate that Sea Lampreys may be vulnerable to alternative trap types near river mouths and hydraulic challenges associated with traditional traps. Also, seasonal migration barriers near stream mouths may need to be installed soon after ice‐out to effectively block the entire adult Sea Lamprey cohort from upstream spawning habitat.

Reconstruction of the 3-D Dynamics From Surface Variables in a High-Resolution Simulation of North Atlantic

NASA Astrophysics Data System (ADS)

Fresnay, S.; Ponte, A. L.; Le Gentil, S.; Le Sommer, J.

2018-03-01

Several methods that reconstruct the three-dimensional ocean dynamics from sea level are presented and evaluated in the Gulf Stream region with a 1/60° realistic numerical simulation. The use of sea level is motivated by its better correlation with interior pressure or quasi-geostrophic potential vorticity (PV) compared to sea surface temperature and sea surface salinity, and, by its observability via satellite altimetry. The simplest method of reconstruction relies on a linear estimation of pressure at depth from sea level. Another method consists in linearly estimating PV from sea level first and then performing a PV inversion. The last method considered, labeled SQG for surface quasi-geostrophy, relies on a PV inversion but assumes no PV anomalies. The first two methods show comparable skill at levels above -800 m. They moderately outperform SQG which emphasizes the difficulty of estimating interior PV from surface variables. Over the 250-1,000 m depth range, the three methods skillfully reconstruct pressure at wavelengths between 500 and 200 km whereas they exhibit a rapid loss of skill between 200 and 100 km wavelengths. Applicability to a real case scenario and leads for improvements are discussed.

Warm ocean surface led to ice margin retreat in central-eastern Baffin Bay during the Younger Dryas

NASA Astrophysics Data System (ADS)

Oksman, Mimmi; Weckström, Kaarina; Miettinen, Arto; Juggins, Stephen; Divine, Dmitry; Jackson, Rebecca; Korsgaard, Niels J.; Telford, Richard; Kucera, Michal

2017-04-01

The Greenland ice sheet stability is linked to fast-flowing ice streams that are influenced by sea surface temperatures (SSTs) at their front. One of the largest ice streams in West Greenland is the Jakobshavn Isbræ, which has been shown to have collapsed at ca. 12.2 kyr BP in the middle of the Younger Dryas (YD) cold period (12.9-11.7 kyr BP). The cause for this collapse is still unknown yet hypotheses, such as warm Atlantic water inflow, have been put forward to explain it. Here we present the first diatom-based high-resolution reconstruction of sea surface conditions in the central-eastern Baffin Bay between 14.0 and 10.2 kyr BP. The sea surface temperatures reveal warmer conditions beginning at ca. 13.4 kyr BP and leading to intensive calving and iceberg discharge from Jakobshavn Isbræ visible as increased sedimentation rates and deposition of coarse-grained material in our sediment stratigraphy. The warm YD ocean surface conditions in Baffin Bay are out of phase with the δ18O record from the North Greenland Ice Core Project (NGRIP) and other SST records from northern North-Atlantic. We show that the ocean has had significant interactions with the Greenland ice sheet in the past and emphasize its importance under the current warming of the North Atlantic.

Constraining Future Sea Level Rise Estimates from the Amundsen Sea Embayment, West Antarctica

NASA Astrophysics Data System (ADS)

Nias, I.; Cornford, S. L.; Edwards, T.; Gourmelen, N.; Payne, A. J.

2016-12-01

The Amundsen Sea Embayment (ASE) is the primary source of mass loss from the West Antarctic Ice Sheet. The catchment is particularly susceptible to grounding line retreat, because the ice sheet is grounded on bedrock that is below sea level and deepening towards its interior. Mass loss from the ASE ice streams, which include Pine Island, Thwaites and Smith glaciers, is a major uncertainty on future sea level rise, and understanding the dynamics of these ice streams is essential to constraining this uncertainty. The aim of this study is to construct a distribution of future ASE sea level contributions from an ensemble of ice sheet model simulations and observations of surface elevation change. A 284 member ensemble was performed using BISICLES, a vertically-integrated ice flow model with adaptive mesh refinement. Within the ensemble parameters associated with basal traction, ice rheology and sub-shelf melt rate were perturbed, and the effect of bed topography and sliding law were also investigated. Initially each configuration was run to 50 model years. Satellite observations of surface height change were then used within a Bayesian framework to assign likelihoods to each ensemble member. Simulations that better reproduced the current thinning patterns across the catchment were given a higher score. The resulting posterior distribution of sea level contributions is narrower than the prior distribution, although the central estimates of sea level rise are similar between the prior and posterior. The most extreme simulations were eliminated and the remaining ensemble members were extended to 200 years, using a simple melt rate forcing.

Assessing occupational exposure to sea lamprey pesticides

PubMed Central

Ceballos, Diana M; Beaucham, Catherine C; Kurtz, Kristine; Musolin, Kristin

2015-01-01

Background: Sea lampreys are parasitic fish found in lakes of the United States and Canada. Sea lamprey is controlled through manual application of the pesticides 3-trifluoromethyl-4-nitrophenol (TFM) and BayluscideTM into streams and tributaries. 3-Trifluoromethyl-4-nitrophenol may cause irritation and central nervous system depression and Bayluscide may cause irritation, dermatitis, blisters, cracking, edema, and allergic skin reactions. Objectives: To assess occupational exposures to sea lamprey pesticides. Methods: We developed a wipe method for evaluating surface and skin contamination with these pesticides. This method was field tested at a biological field station and at a pesticide river application. We also evaluated exposures using control banding tools. Results: We verified TFM surface contamination at the biological station. At the river application, we found surfaces and worker’s skin contaminated with pesticides. Conclusion: We recommended minimizing exposures by implementing engineering controls and improved use of personal protective equipment. PMID:25730600

OSTM/Jason-2 and Jason-1 Tandem Mission View of the Gulf Stream

NASA Image and Video Library

2009-04-27

Created with altimeter data from NASA's Ocean Surface Topography Mission (OSTM)/Jason-2 satellite and the Jason-1 satellite, this image shows a portion of the Gulf Stream off the east coast of the United States. It demonstrates how much more detail is visible in the ocean surface when measured by two satellites than by one alone. The image on the left was created with data from OSTM/Jason-2. The image on the right is the same region but made with combined data from OSTM/Jason-2 and Jason-1.It shows the Gulf Stream's eddies and rings much more clearly. This image is a product of the new interleaved tandem mission of the Jason-1 and Ocean Surface Topography Mission (OSTM)/Jason-2 satellites. (The first global map from this tandem mission is available at PIA11859.) In January 2009, Jason-1 was maneuvered into orbit on the opposite side of Earth from its successor, OSTM/Jason-2 satellite. It takes 10 days for the satellites to cover the globe and return to any one place over the ocean. So, in this new tandem configuration, Jason-1 flies over the same region of the ocean that OSTM/Jason-2 flew over five days earlier. Its ground tracks fall mid-way between those of Jason-2, which are about 315 kilometers (195 miles) apart at the equator. Working together, the two spacecraft measure the surface topography of the ocean twice as often as would be possible with one satellite, and over a 10-day period, they return twice the amount of detailed measurements. Combining data from the two satellites makes it possible to map smaller, more rapidly changing features than one satellite could alone. These images show sea-level anomaly data from the first 14 days of the interleaved orbit of Jason-1 and OSTM/Jason-2, the period beginning on Feb. 20, 2009. An anomaly is a departure from a value averaged over a long period of time. Red and yellow are regions where sea levels are higher than normal. Purple and dark blue show where sea levels are lower. A higher-than-normal sea surface is usually a sign of warm waters below, while lower sea levels indicate cooler than normal temperatures. http://photojournal.jpl.nasa.gov/catalog/PIA11997

Ocean backscatter across the Gulf Stream sea surface temperature front

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

Nghiem, S.V.; Li, F.K.

1997-06-01

Ocean backscatter was measured by the Jet Propulsion Laboratory, with the airborne NUSCAT K{sub u}-band scatterometer, across the Gulf Stream sea surface temperature front during the Surface Wave Dynamics Experiment off the coast of Virginia and Maryland in the winter of 1991. Backscatter across the front between the National Oceanic and Atmospheric Administration experimental coastal buoy A (44024) on the cold side and Discus C buoy (44023) on the warm side shows a difference of more than 5 dB for vertical polarization in many cases. This large frontal backscatter change is observed in all upwind, downwind, and crosswind directions. Themore » sea surface temperature difference measured by the buoys was about 9{degrees}C. The corresponding difference in wind speed cannot account for the large backscatter change in view of geophysical model functions depending only on neutral wind velocity such as SASS. The measured backscatter also has larger upwind-downwind and upwind-crosswind ratios compared to the model results. Furthermore, NUSCAT data reveal that upwind backscatter on the cold side was smaller than or close to crosswind backscatter on the warm side for incidence angles between 30{degrees} to 50{degrees}. This suggests that the temperature front can be detected by the scatterometer at these incidence angles for different wind directions in the cold and warm sides.« less

The influence of local sea surface temperatures on Australian east coast cyclones

NASA Astrophysics Data System (ADS)

Pepler, Acacia S.; Alexander, Lisa V.; Evans, Jason P.; Sherwood, Steven C.

2016-11-01

Cyclones are a major cause of rainfall and extreme weather in the midlatitudes and have a preference for genesis and explosive development in areas where a warm western boundary current borders a continental landmass. While there is a growing body of work on how extratropical cyclones are influenced by the Gulf Stream and Kuroshio Current in the Northern Hemisphere, there is little understanding of similar regions in the Southern Hemisphere including the Australian east coast, where cyclones that develop close to the coast are the main cause of severe weather and coastal flooding. This paper quantifies the impact of east Australian sea surface temperatures (SSTs) on local cyclone activity and behavior, using three different sets of sea surface temperature boundary conditions during the period 2007-2008 in an ensemble of Weather Research and Forecasting Model physics parameterizations. Coastal sea surface temperatures are demonstrated to have a significant impact on the overall frequency of cyclones in this region, with warmer SSTs acting as a trigger for the intensification of weak or moderate cyclones, particularly those of a subtropical nature. However, sea surface temperatures play only a minor role in the most intense cyclones, which are dominated by atmospheric conditions.

A global monthly sea surface temperature climatology

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

Shea, D.J.; Trenberth, K.E.; Reynolds, R.W.

1992-09-01

The paper presents a new global 2 deg x 2 deg monthly sea surface temperature (SST) climatology, referred here to as the Shea-Trenberth-Reynolds (STR) climatology, which was derived by modifying a 1950-1979-based SST climatology from the Climate Analysis Center (CAC), by using data from the Comprehensive Ocean-Atmosphere Data Set to improve the SST estimates in the regions of the Kuroshio and the Gulf Stream. A comparison of the STR climatology with the Alexander and Mobley SST climatology showed that the STR climatology is warmer in the Northern Hemisphere, and colder poleward of 45 deg S. 22 refs.

Optimizing larval assessment to support sea lamprey control in the Great Lakes

USGS Publications Warehouse

Hansen, Michael J.; Adams, Jean V.; Cuddy, Douglas W.; Richards, Jessica M.; Fodale, Michael F.; Larson, Geraldine L.; Ollila, Dale J.; Slade, Jeffrey W.; Steeves, Todd B.; Young, Robert J.; Zerrenner, Adam

2003-01-01

Elements of the larval sea lamprey (Petromyzon marinus) assessment program that most strongly influence the chemical treatment program were analyzed, including selection of streams for larval surveys, allocation of sampling effort among stream reaches, allocation of sampling effort among habitat types, estimation of daily growth rates, and estimation of metamorphosis rates, to determine how uncertainty in each element influenced the stream selection program. First, the stream selection model based on current larval assessment sampling protocol significantly underestimated transforming sea lam-prey abundance, transforming sea lampreys killed, and marginal costs per sea lamprey killed, compared to a protocol that included more years of data (especially for large streams). Second, larval density in streams varied significantly with Type-I habitat area, but not with total area or reach length. Third, the ratio of larval density between Type-I and Type-II habitat varied significantly among streams, and that the optimal allocation of sampling effort varied with the proportion of habitat types and variability of larval density within each habitat. Fourth, mean length varied significantly among streams and years. Last, size at metamorphosis varied more among years than within or among regions and that metamorphosis varied significantly among streams within regions. Study results indicate that: (1) the stream selection model should be used to identify streams with potentially high residual populations of larval sea lampreys; (2) larval sampling in Type-II habitat should be initiated in all streams by increasing sampling in Type-II habitat to 50% of the sampling effort in Type-I habitat; and (3) methods should be investigated to reduce uncertainty in estimates of sea lamprey production, with emphasis on those that reduce the uncertainty associated with larval length at the end of the growing season and those used to predict metamorphosis.

Switch of flow direction in an Antarctic ice stream.

PubMed

Conway, H; Catania, G; Raymond, C F; Gades, A M; Scambos, T A; Engelhardt, H

2002-10-03

Fast-flowing ice streams transport ice from the interior of West Antarctica to the ocean, and fluctuations in their activity control the mass balance of the ice sheet. The mass balance of the Ross Sea sector of the West Antarctic ice sheet is now positive--that is, it is growing--mainly because one of the ice streams (ice stream C) slowed down about 150 years ago. Here we present evidence from both surface measurements and remote sensing that demonstrates the highly dynamic nature of the Ross drainage system. We show that the flow in an area that once discharged into ice stream C has changed direction, now draining into the Whillans ice stream (formerly ice stream B). This switch in flow direction is a result of continuing thinning of the Whillans ice stream and recent thickening of ice stream C. Further abrupt reorganization of the activity and configuration of the ice streams over short timescales is to be expected in the future as the surface topography of the ice sheet responds to the combined effects of internal dynamics and long-term climate change. We suggest that caution is needed when using observations of short-term mass changes to draw conclusions about the large-scale mass balance of the ice sheet.

Synthetic temperature profiles derived from Geosat altimetry: Comparison with air-dropped expendable bathythermograph profiles

NASA Astrophysics Data System (ADS)

Carnes, Michael R.; Mitchell, Jim L.; de Witt, P. Webb

1990-10-01

Synthetic temperature profiles are computed from altimeter-derived sea surface heights in the Gulf Stream region. The required relationships between surface height (dynamic height at the surface relative to 1000 dbar) and subsurface temperature are provided from regression relationships between dynamic height and amplitudes of empirical orthogonal functions (EOFs) of the vertical structure of temperature derived by de Witt (1987). Relationships were derived for each month of the year from historical temperature and salinity profiles from the region surrounding the Gulf Stream northeast of Cape Hatteras. Sea surface heights are derived using two different geoid estimates, the feature-modeled geoid and the air-dropped expendable bathythermograph (AXBT) geoid, both described by Carnes et al. (1990). The accuracy of the synthetic profiles is assessed by comparison to 21 AXBT profile sections which were taken during three surveys along 12 Geosat ERM ground tracks nearly contemporaneously with Geosat overflights. The primary error statistic considered is the root-mean-square (rms) difference between AXBT and synthetic isotherm depths. The two sources of error are the EOF relationship and the altimeter-derived surface heights. EOF-related and surface height-related errors in synthetic temperature isotherm depth are of comparable magnitude; each translates into about a 60-m rms isotherm depth error, or a combined 80 m to 90 m error for isotherms in the permanent thermocline. EOF-related errors are responsible for the absence of the near-surface warm core of the Gulf Stream and for the reduced volume of Eighteen Degree Water in the upper few hundred meters of (apparently older) cold-core rings in the synthetic profiles. The overall rms difference between surface heights derived from the altimeter and those computed from AXBT profiles is 0.15 dyn m when the feature-modeled geoid is used and 0.19 dyn m when the AXBT geoid is used; the portion attributable to altimeter-derived surface height errors alone is 0.03 dyn m less for each. In most cases, the deeper structure of the Gulf Stream and eddies is reproduced well by vertical sections of synthetic temperature, with largest errors typically in regions of high horizontal gradient such as across rings and the Gulf Stream front.

Sea lamprey avoid areas scented with conspecific tissue extract in Michigan streams

USGS Publications Warehouse

Di Rocco, Richard; Johnson, Nicholas; Brege, Linnea; Imre, I.; Brown, G.E.

2016-01-01

Three in-stream experiments were conducted to determine whether sea lamprey, Petromyzon marinus L., tissue extract (alarm cue) and 2-phenylethylamine hydrochloride (PEA HCl, a putative predator cue) influenced the distribution of migrating adult sea lamprey. Experiments evaluated sea lamprey movement when an odour was applied to (1) a tributary of a larger stream; and (2) half of a stream channel. Fewer sea lamprey entered the tributary and side of the river scented with sea lamprey tissue extract compared to the control treatment. Sea lamprey did not avoid the tributary and side of the river scented with PEA HCl. A final laboratory experiment found no difference in the avoidance response of sea lamprey to PEA HCl mixed with river water vs PEA HCl mixed with water from Lake Huron. As such, the lack of sea lamprey response to PEA HCl in the stream was unlikely to have been caused by the presence of the river water. Rather, the difference between laboratory and field results may be attributed to the complexity of the physical environment.

Impact of river discharge on the California coastal ocean circulation and variability

NASA Astrophysics Data System (ADS)

Leiva, J.; Chao, Y.; Farrara, J. D.; Zhang, H.

2016-12-01

A real-time California coastal ocean nowcast and forecast system is used to quantify the impact of river discharge on the California coastal ocean circulation and variability. River discharge and freshwater runoff is monitored by an extensive network of stream gages maintained through the U.S. Geological Survey, that offers archived stream flow records as well as real-time datasets. Of all the rivers monitored by the USGS, 25 empty into the Pacific Ocean and contribute a potential source of runoff data. Monthly averages for the current water year yield discharge estimates as high as 6,000 cubic meters per second of additional freshwater input into our present model. Using Regional Ocean Modeling System (ROMS), we performed simulations from October 2015 to May 2016 with and without the river discharge. Results of these model simulations are compared with available observations including both in situ and satellite. Particular attention is paid to the salinity simulation. Validation is done with comparisons to sea glider data available through Oregon State University and UC San Diego, which provides depth profiles along the California coast during this time period. Additional validation is performed through comparisons with sea surface salinity measurements from the Soil Moisture and Ocean Salinity (SMOS) mission. Continued testing for previous years, e.g. between 2011 and 2015, is being made using the Aquarius sea surface salinity data. Discharge data collected by the USGS stream gages provides a necessary source of freshwater input that must be accounted for. Incorporating a new runoff source produces a more robust model that generates improved forecasts. Following validation with available sea glider and satellite data, the enhanced model can be adapted to real-time forecasting.

Climatic teleconnections between the subtropical and polar North Atlantic during the Last Interglacial period (MIS5e)

NASA Astrophysics Data System (ADS)

Bauch, H. A.; Zhuravleva, A.

2017-12-01

Meridional gradients in sea surface temperature (SST) control ocean-atmosphere circulation patterns and, thus, regulate the global climate. Here we reconstruct variability of these gradients in the course of the Last Interglacial (MIS5e), by using sediment records from the low and high latitude North Atlantic which are linked via the Gulf Stream.In the Nordic Seas, i.e., at the northern end of the Gulf Stream extension, strong post-Saalian meltwater discharge reduced northward-directed transport of surface oceanic heat until the mid-MIS5e, resulting in a late and rather weak SST peak. To decipher the corresponding climatic changes in the area of the Gulf Stream origin, we employ stable isotopes data, planktic foraminifera assemblages as well as a new alkenone paleotemperature record from core drilled on the upper northern slope of the Little Bahama Bank. In addition, chemical composition of sediments (XRF data) was used to asses past sea level fluctuations and sedimentation regimes on this shallow-water carbonate bank. Significant variations in Sr/Ca ratios point to a two-fold structure of the Last Interglacial. Stabilized Sr/Ca values were reached only during the second phase of MIS5e, possibly representing the interval of maximum bank-top flooding after the northern hemisphere deglaciation terminated. Faunal-based proxies as well as oxygen isotopic gradients between surface and bottom-dwelling foraminifera corroborate existence of the two major climatic phases within the Last Interglacial, in agreement with the respective development in the polar region. This further suggests a strong climatic coupling between the subtropical and high-latitude North Atlantic with important implications for meridional SST gradients during the Last Interglacial.

Exploring spatiotemporal changes of the Yangtze River (Changjiang) nitrogen and phosphorus sources, retention and export to the East China Sea and Yellow Sea.

PubMed

Liu, Xiaochen; Beusen, Arthur H W; Van Beek, Ludovicus P H; Mogollón, José M; Ran, Xiangbin; Bouwman, Alexander F

2018-06-04

Nitrogen (N) and phosphorus (P) flows from land to sea in the Yangtze River basin were simulated for the period 1900-2010, by combining models for hydrology, nutrient input to surface water, and an in-stream retention. This study reveals that the basin-wide nutrient budget, delivery to surface water, and in-stream retention increased during this period. Since 2004, the Three Gorges Reservoir has contributed 5% and 7% of N and P basin-wide retention, respectively. With the dramatic rise in nutrient delivery, even this additional retention was insufficient to prevent an increase of riverine export from 337 Gg N yr -1 and 58 Gg P yr -1 (N:P molar ratio = 13) to 5896 Gg N yr -1 and 381 Gg P yr -1 (N:P molar ratio = 35) to the East China Sea and Yellow Sea (ECSYS). The midstream and upstream subbasins dominate the N and P exports to the ECSYS, respectively, due to various human activities along the river. Our spatially explicit nutrient source allocation can aid in the strategic targeting of nutrient reduction policies. We posit that these should focus on improving the agricultural fertilizer and manure use efficiency in the upstream and midstream and better urban wastewater management in the downstream subbasin. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Multi-sensor Improved Sea Surface Temperature (MISST) for GODAE

DTIC Science & Technology

2007-09-30

NAVOCEANO has improved on its methodology to add retrieval error information to the US Navy operational data stream. Quantitative estimates of...hycom.rsmas.miami.edu/ “ POSITIV : Prototype Operational System – ISAR – Temperature Instrumentation for the VOS fleet” CIRA/CSU Joint Hurricane Testbed

Using the glacial geomorphology of palaeo-ice streams to understand mechanisms of ice sheet collapse

NASA Astrophysics Data System (ADS)

Stokes, Chris R.; Margold, Martin; Clark, Chris; Tarasov, Lev

2017-04-01

Processes which bring about ice sheet deglaciation are critical to our understanding of glacial-interglacial cycles and ice sheet sensitivity to climate change. The precise mechanisms of deglaciation are also relevant to our understanding of modern-day ice sheet stability and concerns over global sea level rise. Mass loss from ice sheets can be broadly partitioned between melting and a 'dynamic' component whereby rapidly-flowing ice streams/outlet glaciers transfer ice from the interior to the oceans. Surface and basal melting (e.g. of ice shelves) are closely linked to atmospheric and oceanic conditions, but the mechanisms that drive dynamic changes in ice stream discharge are more complex, which generates much larger uncertainties about their future contribution to ice sheet mass loss and sea level rise. A major problem is that observations of modern-day ice streams typically span just a few decades and, at the ice-sheet scale, it is unclear how the entire drainage network of ice streams evolves during deglaciation. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean-climate forcing. To address this issue, numerous workers have sought to understand ice stream dynamics over longer time-scales using their glacial geomorphology in the palaeo-record. Indeed, our understanding of their geomorphology has grown rapidly in the last three decades, from almost complete ignorance to a detailed knowledge of their geomorphological products. Building on this body of work, this paper uses the glacial geomorphology of 117 ice streams in the North American Laurentide Ice Sheet to reconstruct their activity during its deglaciation ( 22,000 to 7,000 years ago). Ice stream activity was characterised by high variability in both time and space, with ice streams switching on and off in different locations. During deglaciation, we find that their overall number decreased, they occupied a progressively smaller percentage of the ice sheet perimeter, and their total discharge decreased. Underlying geology and topography clearly influenced ice stream activity, but - at the ice sheet scale - their drainage network adjusted and was strongly linked to changes in ice sheet volume. It is unclear whether these findings are directly translatable to modern ice sheets but, contrary to the view that sees ice streams as unstable entities that can draw-down large sectors of an ice sheet and accelerate its demise, we conclude that they reduced in effectiveness during deglaciation of the Laurentide Ice Sheet, with final deglaciation accomplished most effectively by surface melting. This raises some interesting questions about the source and nature of major meltwater pulses and iceberg discharge events in the sea-level record.

Regional Stratification and Shear of the Various Streams Feeding the Philippine Straits

DTIC Science & Technology

2007-09-30

Route 9W Palisades , NY 10964-8000 phone: (845) 365-8325 fax: (845) 365-8157 email: agordon@ldeo.columbia.edu Award Number: N00014-06-1-0689...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Lamont-Doherty Earth Observatory,61 Route 9W, Palisades ,NY,10964- 8. PERFORMING ORGANIZATION REPORT...Sea, the Pacific surface westward flow being the “river”, the Sulu Sea being the “coastal ocean”. There appears to be a double Estuarine cells

Atmospheric Signature of the Agulhas Current

NASA Astrophysics Data System (ADS)

Nkwinkwa Njouodo, Arielle Stela; Koseki, Shunya; Keenlyside, Noel; Rouault, Mathieu

2018-05-01

Western boundary currents play an important role in the climate system by transporting heat poleward and releasing it to the atmosphere. While their influence on extratropical storms and oceanic rainfall is becoming appreciated, their coastal influence is less known. Using satellite and climate reanalysis data sets and a regional atmospheric model, we show that the Agulhas Current is a driver of the observed band of rainfall along the southeastern African coast and above the Agulhas Current. The Agulhas current's warm core is associated with sharp gradients in sea surface temperature and sea level pressure, a convergence of low-level winds, and a co-located band of precipitation. Correlations among wind convergence, sea level pressure, and sea surface temperature indicate that these features show high degree of similarity to those in the Gulf Stream region. Model experiments further indicate that the Agulhas Current mostly impacts convective rainfall.

Assimilation of Altimeter Data into a Quasigeostrophic Model of the Gulf Stream System. Part 1; Dynamical Considerations

NASA Technical Reports Server (NTRS)

Capotondi, Antonietta; Malanotte-Rizzoli, Paola; Holland, William R.

1995-01-01

The dynamical consequences of constraining a numerical model with sea surface height data have been investigated. The model used for this study is a quasigeostrophic model of the Gulf Stream region. The data that have been assimilated are maps of sea surface height obtained as the superposition of sea surface height variability deduced from the Geosat altimeter measurements and a mean field constructed from historical hydrographic data. The method used for assimilating the data is the nudging technique. Nudging has been implemented in such a way as to achieve a high degree of convergence of the surface model fields toward the observations. The assimilation of the surface data is thus equivalent to the prescription of a surface pressure boundary condition. The authors analyzed the mechanisms of the model adjustment and the characteristics of the resultant equilibrium state when the surface data are assimilated. Since the surface data are the superposition of a mean component and an eddy component, in order to understand the relative role of these two components in determining the characteristics of the final equilibrium state, two different experiments have been considered: in the first experiment only the climatological mean field is assimilated, while in the second experiment the total surface streamfunction field (mean plus eddies) has been used. It is shown that the model behavior in the presence of the surface data constraint can be conveniently described in terms of baroclinic Fofonoff modes. The prescribed mean component of the surface data acts as a 'surface topography' in this problem. Its presence determines a distortion of the geostrophic contours in the subsurface layers, thus constraining the mean circulation in those layers. The intensity of the mean flow is determined by the inflow/outflow conditions at the open boundaries, as well as by eddy forcing and dissipation.

Applications of SMART: A DRDC Atmospheric Radiative Transfer Library Optimized for Wide Band Computations

DTIC Science & Technology

2011-06-28

DRDC accurate refracted path calculation – 2-stream (flux) and DISORT (N-stream) MS calculations – Lambert and sea surface (DRDC analytical model ) BRDF ...display a currently valid OMB control number. 1. REPORT DATE 28 JUN 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND...radiance – MODTRAN molecular extinctions (CK) • Seamless integration of MOD4v3r1 – MODTRAN and DRDC aerosol models – Falling snow model (DRDC

No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic.

PubMed

Foukal, Nicholas P; Lozier, M Susan

2016-04-22

Recent Lagrangian analyses of surface drifters have questioned the existence of a surface current connecting the Gulf Stream (GS) to the subpolar gyre (SPG) and have cast doubt on the mechanism underlying an apparent pathway for sea-surface temperature (SST) anomalies between the two regions. Here we use modelled Lagrangian trajectories to determine the fate of surface GS water and satellite SST data to analyse pathways of GS SST anomalies. Our results show that only a small fraction of the surface GS water reaches the SPG, the water that does so mainly travels below the surface mixed layer, and GS SST anomalies do not propagate into the SPG on interannual timescales. Instead, the inter-gyre heat transport as part of the Atlantic Meridional Overturning Circulation must be accomplished via subsurface pathways. We conclude that the SST in the SPG cannot be predicted by tracking SST anomalies along the GS.

No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic

PubMed Central

Foukal, Nicholas P.; Lozier, M. Susan

2016-01-01

Recent Lagrangian analyses of surface drifters have questioned the existence of a surface current connecting the Gulf Stream (GS) to the subpolar gyre (SPG) and have cast doubt on the mechanism underlying an apparent pathway for sea-surface temperature (SST) anomalies between the two regions. Here we use modelled Lagrangian trajectories to determine the fate of surface GS water and satellite SST data to analyse pathways of GS SST anomalies. Our results show that only a small fraction of the surface GS water reaches the SPG, the water that does so mainly travels below the surface mixed layer, and GS SST anomalies do not propagate into the SPG on interannual timescales. Instead, the inter-gyre heat transport as part of the Atlantic Meridional Overturning Circulation must be accomplished via subsurface pathways. We conclude that the SST in the SPG cannot be predicted by tracking SST anomalies along the GS. PMID:27103496

Multi-Sensor Improved Sea Surface Temperature (MISST) for GODAE

DTIC Science & Technology

2008-01-01

its methodology to add 3 retrieval error information to the US Navy operational data stream. Quantitative estimates of reliability are added to...hycom.rsmas.miami.edu/ “ POSITIV : Prototype Operational System – ISAR – Temperature Instrumentation for the VOS fleet” CIRA/CSU Joint Hurricane Testbed project

Air-sea interactions during strong winter extratropical storms

USGS Publications Warehouse

Nelson, Jill; He, Ruoying; Warner, John C.; Bane, John

2014-01-01

A high-resolution, regional coupled atmosphere–ocean model is used to investigate strong air–sea interactions during a rapidly developing extratropical cyclone (ETC) off the east coast of the USA. In this two-way coupled system, surface momentum and heat fluxes derived from the Weather Research and Forecasting model and sea surface temperature (SST) from the Regional Ocean Modeling System are exchanged via the Model Coupling Toolkit. Comparisons are made between the modeled and observed wind velocity, sea level pressure, 10 m air temperature, and sea surface temperature time series, as well as a comparison between the model and one glider transect. Vertical profiles of modeled air temperature and winds in the marine atmospheric boundary layer and temperature variations in the upper ocean during a 3-day storm period are examined at various cross-shelf transects along the eastern seaboard. It is found that the air–sea interactions near the Gulf Stream are important for generating and sustaining the ETC. In particular, locally enhanced winds over a warm sea (relative to the land temperature) induce large surface heat fluxes which cool the upper ocean by up to 2 °C, mainly during the cold air outbreak period after the storm passage. Detailed heat budget analyses show the ocean-to-atmosphere heat flux dominates the upper ocean heat content variations. Results clearly show that dynamic air–sea interactions affecting momentum and buoyancy flux exchanges in ETCs need to be resolved accurately in a coupled atmosphere–ocean modeling framework.

SEASAT views oceans and sea ice with synthetic aperture radar

NASA Technical Reports Server (NTRS)

Fu, L. L.; Holt, B.

1982-01-01

Fifty-one SEASAT synthetic aperture radar (SAR) images of the oceans and sea ice are presented. Surface and internal waves, the Gulf Stream system and its rings and eddies, the eastern North Pacific, coastal phenomena, bathymetric features, atmospheric phenomena, and ship wakes are represented. Images of arctic pack and shore-fast ice are presented. The characteristics of the SEASAT SAR system and its image are described. Maps showing the area covered, and tables of key orbital information, and listing digitally processed images are provided.

The sedimentary evolution of the Celtic Sea during Marine Isotope Stages 1 and 2

NASA Astrophysics Data System (ADS)

Lockhart, Edward; Scourse, James; Van Landeghem, Katrien; Praeg, Daniel; Mellett, Claire; Huws, Dei; Saher, Margot; Benetti, Sara

2017-04-01

During the Last Glacial Maximum (LGM), the Celtic Sea was partially glaciated by the Irish Sea Ice Stream and is considered to have subsequently experienced a high-energy post-glacial transgression. The combination of these events resulted in the deposition, reworking and erosion of a wide range of sediment types to produce the upper stratigraphy of the shelf, including the world's largest submarine elongated ridges. These geomorphic features dominate the shelf and have been previously interpreted to have formed as a result of the tidal reworking of shelf deposits during transgression, despite not having been directly dated. Shelf-wide high-resolution geophysical data, and vibrocores, collected as part of the BRITICE-CHRONO Project, provide new information on relationships between seismic and shallow sedimentary units. A regionally extensive near-surface reflector, cored in several locations, correlates to a gravel/shell layer with an erosive base, unconformably overlying fine-grained LGM glacial sediments with undrained shear strengths in excess of 120 kPa, and in places exhibiting visibly deformed laminations. Geotechnical tests suggest these sediments to be over-consolidated, and we propose that these properties and the observed deformation can only be explained by subglacial reworking under a re-advancing Irish Sea Ice Stream, a scenario never before evidenced in reconstructions of Celtic Sea glaciation. Previous reconstructions propose a single advance-retreat cycle; therefore, a re-advance during a time of inferred retreat would represent a significant change in glacial dynamics. Seismic reflection profiles show that the regionally continuous gravel/shell layer appears to form an undulating palaeo-topography, possibly influenced by the geotechnical properties of the deposits below, on which the large surface ridges are formed. The presence of a regionally continuous reflection surface truncating LGM glacial sediments would suggest a significant erosion event after glacial deposition occurred, possibly representing transgression. This suggests that the large surface ridges may be of post-glacial tidal origin, but with significant sediment supply and morphological control influenced by the glaciation of the Celtic Sea.

Comparison data for Seasat altimetry in the western North Atlantic

NASA Technical Reports Server (NTRS)

Cheney, R. E.

1981-01-01

The radar altimeter flown on Seasat in 1978 collected approximately 1,000 orbits of high quality data (5-8 precision). In the western North Atlantic these data were combined with a detailed gravimetric geoid in an attempt to produce profiles of dynamic topography. In order to provide a basis for evaluation of these profiles, available oceanographic observations in the Gulf Stream/Sargasso Sea region have been compiled into a series of biweekly maps. The data include XBT's, satellite infrared imagery, and selected trajectories of surface drifters and sub-surface SOFAR floats. The maps document the known locations of the Gulf Stream, cyclonic and anticyclonic rings, and mid-ocean eddies during the period July to October 1978.

Selecting Great Lakes streams for lampricide treatment based on larval sea lamprey surveys

USGS Publications Warehouse

Christie, Gavin C.; Adams, Jean V.; Steeves, Todd B.; Slade, Jeffrey W.; Cuddy, Douglas W.; Fodale, Michael F.; Young, Robert J.; Kuc, Miroslaw; Jones, Michael L.

2003-01-01

The Empiric Stream Treatment Ranking (ESTR) system is a data-driven, model-based, decision tool for selecting Great Lakes streams for treatment with lampricide, based on estimates from larval sea lamprey (Petromyzon marinus) surveys conducted throughout the basin. The 2000 ESTR system was described and applied to larval assessment surveys conducted from 1996 to 1999. A comparative analysis of stream survey and selection data was conducted and improvements to the stream selection process were recommended. Streams were selected for treatment based on treatment cost, predicted treatment effectiveness, and the projected number of juvenile sea lampreys produced. On average, lampricide treatments were applied annually to 49 streams with 1,075 ha of larval habitat, killing 15 million larval and 514,000 juvenile sea lampreys at a total cost of $5.3 million, and marginal and mean costs of $85 and $10 per juvenile killed. The numbers of juvenile sea lampreys killed for given treatment costs showed a pattern of diminishing returns with increasing investment. Of the streams selected for treatment, those with > 14 ha of larval habitat targeted 73% of the juvenile sea lampreys for 60% of the treatment cost. Suggested improvements to the ESTR system were to improve accuracy and precision of model estimates, account for uncertainty in estimates, include all potentially productive streams in the process (not just those surveyed in the current year), consider the value of all larvae killed during treatment (not just those predicted to metamorphose the following year), use lake-specific estimates of damage, and establish formal suppression targets.

Simulated interaction between freshwater and saltwater and effects of ground-water pumping and sea-level change, lower Cape Cod aquifer system, Massachusetts

USGS Publications Warehouse

Masterson, John P.

2004-01-01

The U.S. Geological Survey, in cooperation with the National Park Service, Massachusetts Executive Office of Environmental Affairs, Cape Cod Commission, and the Towns of Eastham, Provincetown, Truro, and Wellfleet, began an investigation in 2000 to improve the understanding of the hydrogeology of the four freshwater lenses of the Lower Cape Cod aquifer system and to assess the effects of changing ground-water pumping, recharge conditions, and sea level on ground-water flow in Lower Cape Cod, Massachusetts. A numerical flow model was developed with the computer code SEAWAT to assist in the analysis of freshwater and saltwater flow. Model simulations were used to determine water budgets, flow directions, and the position and movement of the freshwater/saltwater interface. Model-calculated water budgets indicate that approximately 68 million gallons per day of freshwater recharge the Lower Cape Cod aquifer system with about 68 percent of this water moving through the aquifer and discharging directly to the coast, 31 percent flowing through the aquifer, discharging to streams, and then reaching the coast as surface-water discharge, and the remaining 1 percent discharging to public-supply wells. The distribution of streamflow varies greatly among flow lenses and streams; in addition, the subsurface geology greatly affects the position and movement of the underlying freshwater/saltwater interface. The depth to the freshwater/saltwater interface varies throughout the study area and is directly proportional to the height of the water table above sea level. Simulated increases in sea level appear to increase water levels and streamflows throughout the Lower Cape Cod aquifer system, and yet decrease the depth to the freshwater/saltwater interface. The resulting change in water levels and in the depth to the freshwater/saltwater interface from sea-level rise varies throughout the aquifer system and is controlled largely by non-tidal freshwater streams. Pumping from large-capacity municipal-supply wells increases the potential for effects on surface-water bodies, which are affected by pumping and wastewater-disposal locations and rates. Pumping wells that are upgradient of surface-water bodies potentially capture water that would otherwise discharge to these surface-water bodies, thereby reducing streamflow and pond levels. Kettle-hole ponds, such as Duck Pond in Wellfleet, that are near the top of a freshwater flow lens, appear to be more susceptible to changing pumping and recharge conditions than kettle-hole ponds closer to the coast or near discharge boundaries, such as the Herring River.

Shifting Surface Currents in the Northern North Atlantic Ocean

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Rhines, Peter B.

2007-01-01

Analysis of surface drifter tracks in the North Atlantic Ocean from the time period 1990 to 2006 provides the first evidence that the Gulf Stream waters can have direct pathways to the Nordic Seas. Prior to 2000, the drifters entering the channels leading to the Nordic Seas originated in the western and central subpolar region. Since 2001 several paths from the western subtropics have been present in the drifter tracks leading to the Rockall Trough through which the most saline North Atlantic Waters pass to the Nordic Seas. Eddy kinetic energy from altimetry shows also the increased energy along the same paths as the drifters, These near surface changes have taken effect while the altimetry shows a continual weakening of the subpolar gyre. These findings highlight the changes in the vertical structure of the northern North Atlantic Ocean, its dynamics and exchanges with the higher latitudes, and show how pathways of the thermohaline circulation can open up and maintain or increase its intensity even as the basin-wide circulation spins down.

Potential effects of sea-level rise on the depth to saturated sediments of the Sagamore and Monomoy flow lenses on Cape Cod, Massachusetts

USGS Publications Warehouse

Walter, Donald A.; McCobb, Timothy D.; Masterson, John P.; Fienen, Michael N.

2016-05-25

In 2014, the U.S. Geological Survey, in cooperation with the Association to Preserve Cape Cod, the Cape Cod Commission, and the Massachusetts Environmental Trust, began an evaluation of the potential effects of sea-level rise on water table altitudes and depths to water on central and western Cape Cod, Massachusetts. Increases in atmospheric and oceanic temperatures arising, in part, from the release of greenhouse gases likely will result in higher sea levels globally. Increasing water table altitudes in shallow, unconfined coastal aquifer systems could adversely affect infrastructure—roads, utilities, basements, and septic systems—particularly in low-lying urbanized areas. The Sagamore and Monomoy flow lenses on Cape Cod are the largest and most populous of the six flow lenses that comprise the region’s aquifer system, the Cape Cod glacial aquifer. The potential effects of sea-level rise on water table altitude and depths to water were evaluated by use of numerical models of the region. The Sagamore and Monomoy flow lenses have a number of large surface water drainages that receive a substantial amount of groundwater discharge, 47 and 29 percent of the total, respectively. The median increase in the simulated water table altitude following a 6-foot sea-level rise across both flow lenses was 2.11 feet, or 35 percent when expressed as a percentage of the total sea-level rise. The response is nearly the same as the sea-level rise (6 feet) in some coastal areas and less than 0.1 foot near some large inland streams. Median water table responses differ substantially between the Sagamore and Monomoy flow lenses—at 29 and 49 percent, respectively—because larger surface water discharge on the Sagamore flow lens results in increased dampening of the water table response than in the Monomoy flow lens. Surface waters dampen water table altitude increases because streams are fixed-altitude boundaries that cause hydraulic gradients and streamflow to increase as sea-level rises, partially fixing the local water table altitude.The region has a generally thick vadose zone with a mean of about 38 feet; areas with depths to water of 5 feet or less, as estimated from light detection and ranging (lidar) data from 2011 and simulated water table altitudes, currently [2011] occur over about 24.9 square miles, or about 8.4 percent of the total land area of the Sagamore and Monomoy flow lenses, generally in low-lying coastal areas and inland near ponds and streams. Excluding potentially submerged areas, an additional 4.5, 9.8, and 15.9 square miles would have shallow depths to water (5 feet or less) for projected sea-level rises of 2, 4, and 6 feet above levels in 2011. The additional areas with shallow depths to water generally occur in the same areas as the areas with current [2011] depths to water of 5 feet or less: low-lying coastal areas and near inland surface water features. Additional areas with shallow depths to water for the largest sea-level rise prediction (6 feet) account for about 5.7 percent of the total land area, excluding areas likely to be inundated by seawater. The numerous surface water drainages will dampen the response of the water table to sea-level rise. This dampening, combined with the region’s thick vadose zone, likely will mitigate the potential for groundwater inundation in most areas. The potential does exist for groundwater inundation in some areas, but the effects of sea-level rise on depths to water and infrastructure likely will not be substantial on a regional level.

Turbulent convection driven by internal radiative heating of melt ponds on sea ice

NASA Astrophysics Data System (ADS)

Wells, Andrew; Langton, Tom; Rees Jones, David; Moon, Woosok

2016-11-01

The melting of Arctic sea ice is strongly influenced by heat transfer through melt ponds which form on the ice surface. Melt ponds are internally heated by the absorption of incoming radiation and cooled by surface heat fluxes, resulting in vigorous buoyancy-driven convection in the pond interior. Motivated by this setting, we conduct two-dimensional direct-numerical simulations of the turbulent convective flow of a Boussinesq fluid between two horizontal boundaries, with internal heating predicted from a two-stream radiation model. A linearised thermal boundary condition describes heat exchange with the overlying atmosphere, whilst the lower boundary is isothermal. Vertically asymmetric convective flow modifies the upper surface temperature, and hence controls the partitioning of the incoming heat flux between emission at the upper and lower boundaries. We determine how the downward heat flux into the ice varies with a Rayleigh number based on the internal heating rate, the flux ratio of background surface cooling compared to internal heating, and a Biot number characterising the sensitivity of surface fluxes to surface temperature. Thus we elucidate the physical controls on heat transfer through Arctic melt ponds which determine the fate of sea ice in the summer.

El Niño rides again

NASA Astrophysics Data System (ADS)

Friebele, Elaine

Another weather-disrupting El Niño may be brewing in the Pacific Ocean, according to ocean measurements taken by NASA instruments on two orbiting satellites. Sea-surface height measurements taken by the radar altimeter on board the joint U.S.-French TOPEX/Poseidon satellite and wind data collected by the NASA scatterometer on Japan's Advanced Earth Observing Satellite (ADEOS) have been used together for the first time to predict changing weather conditions in the tropical Pacific Ocean.El Niño occurs when steady westward blowing trade winds weaken and reverse direction, moving the mass of warm water near Australia eastward to the coast of South America. The displacement of the warm water mass alters the atmospheric jet stream and weather patterns around the world. The TOPEX/Poseidon satellite uses an altimeter to bounce radar signals off the ocean's surface to make precise measurements of the distance between the satellite and sea surface. Researchers then map the barely perceptible hills and valleys of the sea surface by combining these data with measurements pinpointing the satellite's exact location in space.

Effects of sea lamprey substrate modification and carcass nutrients on macroinvertebrate assemblages in a small Atlantic coastal stream

USGS Publications Warehouse

Weaver, Daniel M.; Coghlan, Stephen M.; Zydlewski, Joseph D.

2018-01-01

Aquatic macroinvertebrates respond to patch dynamics arising from interactions of physical and chemical disturbances across space and time. Anadromous fish, such as sea lamprey, Petromyzon marinus, migrate from the ocean and alter physical and chemical properties of recipient spawning streams. Sea lamprey disturb stream benthos physically through nest construction and spawning, and enrich food webs through nutrient deposition from decomposing carcasses. Sea lamprey spawning nests support greater macroinvertebrate abundance than adjacent reference areas, but concurrent effects of stream bed modification and nutrient supplementation have not been examined sequentially. We added carcasses and cleared substrate experimentally to mimic the physical disturbance and nutrient enrichment associated with lamprey spawning, and characterized effects on macroinvertebrate assemblage structure. We found that areas receiving cleared substrate and carcass nutrients were colonized largely by Simuliidae compared to upstream and downstream control areas that were colonized largely by Hydropsychidae, Philopotamidae, and Chironomidae. Environmental factors such as stream flow likely shape assemblages by physically constraining macroinvertebrate establishment and feeding. Our results indicate potential changes in macroinvertebrate assemblages from the physical and chemical changes to streams brought by spawning populations of sea lamprey.

The refreezing of melt ponds on Arctic sea ice

NASA Astrophysics Data System (ADS)

Flocco, Daniela; Feltham, Daniel L.; Bailey, Eleanor; Schroeder, David

2015-02-01

The presence of melt ponds on the surface of Arctic sea ice significantly reduces its albedo, inducing a positive feedback leading to sea ice thinning. While the role of melt ponds in enhancing the summer melt of sea ice is well known, their impact on suppressing winter freezing of sea ice has, hitherto, received less attention. Melt ponds freeze by forming an ice lid at the upper surface, which insulates them from the atmosphere and traps pond water between the underlying sea ice and the ice lid. The pond water is a store of latent heat, which is released during refreezing. Until a pond freezes completely, there can be minimal ice growth at the base of the underlying sea ice. In this work, we present a model of the refreezing of a melt pond that includes the heat and salt balances in the ice lid, trapped pond, and underlying sea ice. The model uses a two-stream radiation model to account for radiative scattering at phase boundaries. Simulations and related sensitivity studies suggest that trapped pond water may survive for over a month. We focus on the role that pond salinity has on delaying the refreezing process and retarding basal sea ice growth. We estimate that for a typical sea ice pond coverage in autumn, excluding the impact of trapped ponds in models overestimates ice growth by up to 265 million km3, an overestimate of 26%.

TOPEX/El Nino Watch - Satellite shows El Nino-related Sea Surface Height, Mar, 14, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

Techniques and methods for estimating abundance of larval and metamorphosed sea lampreys in Great Lakes tributaries, 1995 to 2001

USGS Publications Warehouse

Slade, Jeffrey W.; Adams, Jean V.; Christie, Gavin C.; Cuddy, Douglas W.; Fodale, Michael F.; Heinrich, John W.; Quinlan, Henry R.; Weise, Jerry G.; Weisser, John W.; Young, Robert J.

2003-01-01

Before 1995, Great Lakes streams were selected for lampricide treatment based primarily on qualitative measures of the relative abundance of larval sea lampreys, Petromyzon marinus. New integrated pest management approaches required standardized quantitative measures of sea lamprey. This paper evaluates historical larval assessment techniques and data and describes how new standardized methods for estimating abundance of larval and metamorphosed sea lampreys were developed and implemented. These new methods have been used to estimate larval and metamorphosed sea lamprey abundance in about 100 Great Lakes streams annually and to rank them for lampricide treatment since 1995. Implementation of these methods has provided a quantitative means of selecting streams for treatment based on treatment cost and estimated production of metamorphosed sea lampreys, provided managers with a tool to estimate potential recruitment of sea lampreys to the Great Lakes and the ability to measure the potential consequences of not treating streams, resulting in a more justifiable allocation of resources. The empirical data produced can also be used to simulate the impacts of various control scenarios.

75 FR 28596 - Bryant Mountain LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... acre-feet and normal water surface elevation of 5500 feet mean sea level; (2) an earthen dam... facility to release water into the stream below the dam; and (4) intake facilities for the power tunnel with facilities to store additional water to provide black start capability. Lower Reservoir (1) Will...

Transport driven by eddy momentum fluxes in the Gulf Stream Extension region

NASA Astrophysics Data System (ADS)

Greatbatch, R. J.; Zhai, X.; Claus, M.; Czeschel, L.; Rath, W.

2010-12-01

The importance of the Gulf Stream Extension region in climate and seasonal prediction research is being increasingly recognised. Here we use satellite-derived eddy momentum fluxes to drive a shallow water model for the North Atlantic Ocean that includes the realistic ocean bottom topography. The results show that the eddy momentum fluxes can drive significant transport, sufficient to explain the observed increase in transport of the Gulf Stream following its separation from the coast at Cape Hatteras, as well as the observed recirculation gyres. The model also captures recirculating gyres seen in the mean sea surface height field within the North Atlantic Current system east of the Grand Banks of Newfoundland, including a representation of the Mann Eddy.

Aerial Observations of Symmetric Instability at the North Wall of the Gulf Stream

NASA Astrophysics Data System (ADS)

Savelyev, I.; Thomas, L. N.; Smith, G. B.; Wang, Q.; Shearman, R. K.; Haack, T.; Christman, A. J.; Blomquist, B.; Sletten, M.; Miller, W. D.; Fernando, H. J. S.

2018-01-01

An unusual spatial pattern on the ocean surface was captured by thermal airborne swaths taken across a strong sea surface temperature front at the North Wall of the Gulf Stream. The thermal pattern on the cold side of the front resembles a staircase consisting of tens of steps, each up to ˜200 m wide and up to ˜0.3°C warm. The steps are well organized, clearly separated by sharp temperature gradients, mostly parallel and aligned with the primary front. The interpretation of the airborne imagery is aided by oceanographic measurements from two research vessels. Analysis of the in situ observations indicates that the front was unstable to symmetric instability, a type of overturning instability that can generate coherent structures with similar dimensions to the temperature steps seen in the airborne imagery. It is concluded that the images capture, for the first time, the surface temperature field of symmetric instability turbulence.

The East Asian Jet Stream and Asian-Pacific Climate

NASA Technical Reports Server (NTRS)

Yang, Song; Lau, K.-M.; Kim, K.-M.

1999-01-01

In this study, the NASA GEOS and NCEP/NCAR reanalyses and GPCP rainfall data have been used to study the variability of the East Asian westerly jet stream and its impact on the Asian-Pacific climate, with a focus on interannual time scales. Results indicate that external forcings such as sea surface temperature (SST) and land surface processes also play an important role in the variability of the jet although this variability is strongly governed by internal dynamics. There is a close link between the jet and Asian-Pacific climate including the Asian winter monsoon and tropical convection. The atmospheric teleconnection pattern associated with the jet is different from the ENSO-related pattern. The influence of the jet on eastern Pacific and North American climate is also discussed.

Are North Slope surface alluvial fans pre-Holocene relicts?

USGS Publications Warehouse

Reimnitz, Erk; Wolf, Stephen C.

1998-01-01

The surface morphology of the northern slope of the Brooks Range (North Slope) from the Canning River, Alaska, eastward is dominated by a series of large alluvial fans and braided streams floored by coarse alluvium. On the basis of our studies, we conclude that the fans are not prograding now nor have they been prograding at any time during the Holocene. During the latest transgression and the following sea-level highstand, the North Slope depositional environment and climate probably differed greatly from the present ones.

ERTS-1 observations of sea surface circulation and sediment transport, Cook Inlet, Alaska

NASA Technical Reports Server (NTRS)

Wright, F. F.; Sharma, G. D.; Burbank, D. C.

1973-01-01

Cook Inlet is a large tide-dominated estuary in southern Alaska. Highly turbid streams enter the upper inlet, providing an excellent tracer for circulation in the lower inlet. MSS 4 and 5 images both can be used in this area to plot sediment and pollutant trajectories, areas of (probable) commercial fish concentration, and the entire circulation regime.

Ground Water in the Southern Lihue Basin, Kauai, Hawaii

USGS Publications Warehouse

Izuka, Scot K.; Gingerich, Stephen B.

1998-01-01

A multi-phased study of ground-water resources, including well drilling, aquifer tests, analysis of ground-water discharge, and numerical ground-water modeling, indicates that the rocks of the southern Lihue Basin, Kauai, have permeabilities that are much lower than in most other areas of ground-water development in the Hawaiian islands. The regional hydraulic conductivity of the Koloa Volcanics, which dominates fresh ground-water flow in the basin, is about 0.275 foot per day. The Waimea Canyon Basalt which surrounds the basin and underlies the Koloa Volcanics within the basin is intruded by dikes that reduce the bulk hydraulic conductivity of the rocks to about 1.11 feet per day. The low permeabilities result in steeper head gradients compared with other areas in the Hawaiian islands, and a higher proportion of ground-water discharging to streams than to the ocean. Water levels rise from near sea level at the coast to several hundreds of feet above sea level at the center of the basin a few miles inland. The high inland water levels are part of a completely saturated ground-water system. Because of the low regional hydraulic conductivity and high influx of water from recharge in the southern Lihue Basin, the rocks become saturated nearly to the surface and a variably saturated/unsaturated (perched) condition is not likely to exist. Streams incising the upper part of the aquifer drain ground water and keep the water levels just below the surface in most places. Streams thus play an important role in shaping the water table in the southern Lihue Basin. At least 62 percent of the ground water discharging from the aquifer in the southern Lihue Basin seeps to streams; the remainder seeps directly to the ocean or is withdrawn by wells.

Sources and compositional distribution of organic carbon in surface sediments from the lower Pearl River to the coastal South China Sea

NASA Astrophysics Data System (ADS)

Li, X.; Zhang, Z.; Wade, T.; Knap, A. H.; Zhang, C.

2017-12-01

The Pearl River plays an important role in transporting terrestrial organic carbon (OC) to the South China Sea (SCS). However, the sources and compositional distribution of OC in the system are poorly understood. This study focused on delineating the sources and determining the fate of surface sedimentary OC from the Feilaixia Hydro-power Station to the coastal SCS. Elemental, stable carbon/nitrogen isotope (δ13C, δ15N) and lignin-phenol analyses have been conducted. The total OC (TOC) from the up-stream sites were generally derived from vascular plants (higher C/N, and depleted δ13C) and soils. Additional input was attributed to riverine primary production (lower C/N and enriched δ13C), which was enhanced near the dam-created reservoir. The C/N and δ13C values were not significantly different among sites in the mid-stream. The estuary/coastal sites witnessed hydrodynamically sorted riverine OC, which was diluted by marine primary production (lower C/N and more enriched δ13C). The lignin concentration was the highest in the up-stream sites, remained relatively unchanged in the mid-stream sites and decreased significantly along the estuary/coastal sites, which was corroborated by variation in TOC. A comprehensive five-endmember Monte Carlo simulation suggested that previous studies had underestimated the C4 plant input by 14 ± 11% and overestimated the riverbank soil input by 21 ± 17%. Thus, our study provided valuable information for more accurate source and mass balance studies of terrestrial OC transported to the SCS, which helped to further understand the carbon cycling in the large river-ocean continuum.

The Interrelationship Between Temperature Changes in the Free Atmosphere and Sea Surface Temperature Changes

NASA Astrophysics Data System (ADS)

Newell, Reginald E.; Wu, Zhong-Xiang

1992-03-01

Fields of sea surface temperature anomalies from the Global Ocean Surface Temperature Atlas (GOSTA) and microwave sounding measurements (MSU) of temperature in the troposphere are examined separately and together for the 1979-1988 period. Global correlation patterns of both sets of fields are investigated at a range of leads and lags up to 6 months and exhibit a wide range of correlation structure. There are regions, such as the tropical eastern Pacific, where sea surface temperature anomalies persist for several months and are associated with local air temperature anomalies; in this particular example, about 0.7°C air temperature change is associated with a 1.0°C sea temperature change. By contrast, some ocean regions and many atmospheric regions, mostly in middle and high latitude, show only local spatial correlations that disappear completely in a month or two. The most persistent and extensive spatial correlation patterns are quite different for the sea and the air. In the sea the "butterfly" pattern of the Pacific is the most important and reverses sign between the eastern equatorial Pacific and the western Pacific and subtropics. In the warm phase the temperature anomalies associated with this pattern are similar to the correlation pattern. For the atmosphere the main correlation pattern is an equatorial belt with no sign changes in the tropics; this pattern is linked to the oceanic El Niño mode. In the warm phase the temperature anomalies show peak values on both sides of the equator in the eastern and central Pacific. Based mainly on the results from the spatial patterns, certain regions are selected for intercomparison of time series. In the tropical eastern Pacific the sea leads the air by about a month while in the Gulf Stream and Kuroshio regions the sequence is reversed.

Observational evidence of European summer weather patterns predictable from spring

NASA Astrophysics Data System (ADS)

Ossó, Albert; Sutton, Rowan; Shaffrey, Len; Dong, Buwen

2018-01-01

Forecasts of summer weather patterns months in advance would be of great value for a wide range of applications. However, seasonal dynamical model forecasts for European summers have very little skill, particularly for rainfall. It has not been clear whether this low skill reflects inherent unpredictability of summer weather or, alternatively, is a consequence of weaknesses in current forecast systems. Here we analyze atmosphere and ocean observations and identify evidence that a specific pattern of summertime atmospheric circulation––the summer East Atlantic (SEA) pattern––is predictable from the previous spring. An index of North Atlantic sea-surface temperatures in March–April can predict the SEA pattern in July–August with a cross-validated correlation skill above 0.6. Our analyses show that the sea-surface temperatures influence atmospheric circulation and the position of the jet stream over the North Atlantic. The SEA pattern has a particularly strong influence on rainfall in the British Isles, which we find can also be predicted months ahead with a significant skill of 0.56. Our results have immediate application to empirical forecasts of summer rainfall for the United Kingdom, Ireland, and northern France and also suggest that current dynamical model forecast systems have large potential for improvement.

Factors influencing capture of invasive sea lamprey in traps baited with a synthesized sex pheromone component

USGS Publications Warehouse

Johnson, Nicholas; Siefkes, Michael J.; Wagner, C. Michael; Bravener, Gale; Steeves, Todd; Twohey, Michael; Li, Weiming

2015-01-01

The sea lamprey, Petromyzon marinus, is emerging as a model organism for understanding how pheromones can be used for manipulating vertebrate behavior in an integrated pest management program. In a previous study, a synthetic sex pheromone component 7α,12α, 24-trihydroxy-5α-cholan-3-one 24-sulfate (3kPZS) was applied to sea lamprey traps in eight streams at a final in-stream concentration of 10−12 M. Application of 3kPZS increased sea lamprey catch, but where and when 3kPZS had the greatest impact was not determined. Here, by applying 3kPZS to additional streams, we determined that overall increases in yearly exploitation rate (proportion of sea lampreys that were marked, released, and subsequently recaptured) were highest (20–40 %) in wide streams (~40 m) with low adult sea lamprey abundance (<1000). Wide streams with low adult abundance may be representative of low-attraction systems for adult sea lamprey and, in the absence of other attractants (larval odor, sex pheromone), sea lamprey may have been more responsive to a partial sex pheromone blend emitted from traps. Furthermore, we found that the largest and most consistent responses to 3kPZS were during nights early in the trapping season, when water temperatures were increasing. This may have occurred because, during periods of increasing water temperatures, sea lamprey become more active and males at large may not have begun to release sex pheromone. In general, our results are consistent with those for pheromones of invertebrates, which are most effective when pest density is low and when pheromone competition is low.

Midwestern streamflow, precipitation, and atmospheric vorticity influenced by Pacific sea-surface temperatures and total solar-irradiance variations

USGS Publications Warehouse

Perry, C.A.

2006-01-01

A solar effect on streamflow in the Midwestern United States is described and supported in a six-step physical connection between total solar irradiance (TSI), tropical sea-surface temperatures (SSTs), extratropical SSTs, jet-stream vorticity, surface-layer vorticity, precipitation, and streamflow. Variations in the correlations among the individual steps indicate that the solar/hydroclimatic mechanism is complex and has a time element (lag) that may not be constant. Correct phasing, supported by consistent spectral peaks between 0.092 and 0.096 cycles per year in all data sets within the mechanism is strong evidence for its existence. A significant correlation exists between total solar irradiance and the 3-year moving average of annual streamflow for Iowa (R = 0.67) and for the Mississippi River at St Louis, Missouri (R = 0.60), during the period 1950-2000. Published in 2005 by John Wiley & Sons, Ltd.

Rivers and streams: Physical setting and adapted biota

USGS Publications Warehouse

Wilzbach, Margaret A.; Cummins, K.W.

2008-01-01

Streams and rivers are enormously important, with their ecological, and economic value, greatly outweighing their significance on the landscape. Lotic ecology began in Europe with a focus on the distribution, abundance, and taxonomic composition of aquatic organisms and in North American with a focus on fishery biology. Since 1980, stream/river research has been highly interdisciplinary, involving fishery biologists, aquatic entomologists, algologists, hydrologists, geomorphologists, microbiologists, and terrestrial plant ecologists. Stream and river biota evolved in response to, and in concert with, the physical and chemical setting. Streams/rivers transport water and move sediments to the sea as part of the hydrologic cycle that involves evaporation, plant evapotranspiration, and precipitation. Ephemeral streams flow only in the wettest year, intermittent streams flow predictably every year during capture of surface runoff, and perennial streams flow continuously during wet and dry periods, receiving both stormflow and groundwater baseflow. The lotic biota, for example, algae, macrophytes, benthic invertebrates, and fishes, have evolved adaptations to their running-water setting. Dominant physical features of this setting are current, substrate, and temperature. Key chemical constituents are dissolved gases, dissolved inorganic ions and compounds, particulate inorganic material, particulate organic material, and dissolved organic ions (nitrogen and phosphorus) and compounds.

Quantifying surface water runoff from Wadi Arogut towards the Dead Sea

NASA Astrophysics Data System (ADS)

Geyer, Stefan; Khayat, Saed; Marei, Amer

2015-04-01

The surrounded area of the Dead Sea, especially the west side suffers from many hydrological problems. While the Dead Sea level drop considered a major problem that affect the quality of the surrounded freshwater resources, a lot of the surface water flood from the adjacent Wadi are lost through direct run off without any exploitation. Therefore, it is necessary to maintain a type of balance between surface water exploitation through the Wadi and at the same time allow a sufficient amount of flow to the Dead Sea to ensure its sustainability. In this study, we choose one of the larger tributaries in the western side of the Dead Sea basin. The stream was modelled for runoff response to different rainfall amount and climate conditions (dry, normal, and wet seasons) which were chosen from the rainy seasons in the previous 30 years. Finally, the amount of surface water contribution from each of the three seasons of the Dead Sea was quantified. The outcome of the model shows the results from the normal rainy season, which is frequently reoccurs and common in the region. The model data show that such events normally contribute with about 18-22 MCM annually to the Dead Sea. The problem is with the recurrence of dry season such as 2005/2006, by which the amount of the surface water decrease and consequently has adverse effect on the Dead Sea. However, the presence of less frequent thunder storm season such as that one in 1991/1992 has also a positive effect on the Dead Sea level. In the rainy season 1991/1992 there was a higher amount of rainfall over the study area that reaches around 155 MCM. Despite the presence of this high amount most of the recharge lost to the ground as groundwater recharge. The high amount of rain increases the amount of inundated surface water out of the Wadi banks and covers more surfaces all over the study area, which in role promote more water loss to the ground. That is why the total loss (rather than surface runoff) was much higher (77%). Moreover, 50% less precipitation in 2006 decrease the Dead Sea five metres within five years, and 60% 1992 increase of precipitation raise the water level two metre only for two to three next years. How can we balance the groundwater needs and the Dead Sea survival with those 40% surface water? By no mean: preventing the Dead Sea decline by increasing runoff will not only preventing the fresh water deterioration, but also it will be in the account of groundwater recharge in the surrounding aquifers of the Dead Sea. These conclusions suggest strongly the need of an integrated groundwater model, in order to quantify all scenarios.

Assimilation of Altimeter Data into a Quasigeostrophic Model of the Gulf Stream System. Part 2; Assimilation Results

NASA Technical Reports Server (NTRS)

Capotondi, Antonietta; Holland, William R.; Malanotte-Rizzoli, Paola

1995-01-01

The improvement in the climatological behavior of a numerical model as a consequence of the assimilation of surface data is investigated. The model used for this study is a quasigeostrophic (QG) model of the Gulf Stream region. The data that have been assimilated are maps of sea surface height that have been obtained as the superposition of sea surface height variability deduced from the Geosat altimeter measurements and a mean field constructed from historical hydrographic data. The method used for assimilating the data is the nudging technique. Nudging has been implemented in such a way as to achieve a high degree of convergence of the surface model fields toward the observations. Comparisons of the assimilation results with available in situ observations show a significant improvement in the degree of realism of the climatological model behavior, with respect to the model in which no data are assimilated. The remaining discrepancies in the model mean circulation seem to be mainly associated with deficiencies in the mean component of the surface data that are assimilated. On the other hand, the possibility of building into the model more realistic eddy characteristics through the assimilation of the surface eddy field proves very successful in driving components of the mean model circulation that are in relatively good agreement with the available observations. Comparisons with current meter time series during a time period partially overlapping the Geosat mission show that the model is able to 'correctly' extrapolate the instantaneous surface eddy signals to depths of approximately 1500 m. The correlation coefficient between current meter and model time series varies from values close to 0.7 in the top 1500 m to values as low as 0.1-0.2 in the deep ocean.

An Imminent Revolution in Modeling Interactions of Ice Sheets With Climate

NASA Astrophysics Data System (ADS)

Hughes, T.

2008-12-01

Modeling continental ice sheets was inaugurated by meteorologists William Budd and Uwe Radok, with mathematician Richard Jenssen, in 1971. Their model calculated the thermal and mechanical regime using measured surface accumulation rates, temperatures, and elevations, and bed topography. This top-down approach delivered a basal thermal regime of temperatures or melting rates for an assumed basal geothermal heat flux. When Philippe Huybrechts and others incorporated time, largely unknownpast surface conditions had a major effect on present basal thermal conditions. This approach produced ice-sheet models with only a slow response to external forcing, whereas the glacial geological record and climate records from ice and ocean cores show that ice sheets can have rapid changes in size and shape independent of external forcing. These top-down models were wholly inadequate for reconstructing former ice sheets at the LGM for CLIMAP in 1981. Ice-sheet areas,elevations, and volumes provided the albedo, surface topography, and sea-surface area as input to climate models. A bottom-up model based on dated glacial geology was developed to provide the areal extent and basal thermal regime of ice sheets at the LGM. Basal thermal conditions determined ice-bed coupling and therefore the elevation of ice sheets. High convex ice surfaces for slow sheet flow lower about 20 percent when a frozen bed becomes thawed. As further basal melting drowns bedrock bumps that "pin" basal ice, the ice surface becomes concave in fast stream flow that ends as low floating ice shelves at marine ice margins. A revolution in modeling interactions between glaciation, climate, and sea level is driven by new Greenland and Antarctic data from Earth-orbiting satellites, airborne and surface traverses, and deep drilling. We anticipate continuous data acquisition of surface albedo, accumulation/ablation rates, elevations, velocities, and temperatures over a whole ice sheet, mapping basal thermal conditions by radar, seismic, and magnetic profiling, and direct measurement of basal conditions by deep drilling and coring into the ice and the bed. These data allow calculating the geothermal heat flux and mapping flow of basal meltwater from geothermal sources to sinks at the termini of ice streams, which discharge up to 90 percent of the ice. James Fastook has a preliminary solution of the full momentum equation needed to model ice streams. Douglas MacAyeal has pioneered modeling catastrophic ice-shelf disintegration that releases "armadas" of icebergs into the world ocean, to extract heat from ocean surface water and thereby reduce the critical ocean-to-atmosphere heat exchange that drives global climate. Ice sheets are the only component of Earth's climate machine that can destroy itself-- swiftly--and thereby radically and rapidly alter global climate and sea level.

A Paleo Perspective on Arctic and Mid-latitude Linkages from a Southeast Alaska Ice Core

NASA Astrophysics Data System (ADS)

Porter, S. E.; Mosley-Thompson, E.; Thompson, L. G.; Bolzan, J. F.

2017-12-01

Recent extreme weather events in the Northern Hemisphere have been linked to anomalously amplified jet stream patterns, North Pacific marine heatwaves, retreating Arctic sea ice extent, and/or the combination thereof. The role of the Arctic in influencing mid-latitude weather and extreme events is a burgeoning topic of climate research that is limited primarily to the recent decades in which Arctic amplification and shrinking Arctic sea ice extent are occurring. Paleo-proxy data afford an opportunity to place the changing Arctic and its far-reaching climatic consequences in the longer context of Earth's climate history and allow identification of time periods with conditions analogous to the present. Ice core-derived annual net accumulation from the Bona-Churchill (BC) ice core, retrieved in 2002 from the Wrangell-St. Elias mountain range in southeast Alaska, is used to explore the historical characteristics of the regional North Pacific climate and the further afield teleconnections. Variability of accumulation on BC is driven primarily by shifts in the position of the Aleutian Low which influences the available moisture sources for the drill site. The accumulation record is also related to sea surface temperatures in the Gulf of Alaska, defined here by the North Pacific Mode and somewhat colloquially as the North Pacific "blob". Thus due to its connection with the Aleutian Low and North Pacific sea surface temperatures, this uniquely situated ice core record indirectly captures the phasing of troughs and ridges in the polar jet stream over North America, and thereby facilitates examination of the atmospheric wave structure prior to the instrumental record. The relationships among the ice core accumulation record and various North Pacific climate features are presented along with evidence identifying specific time periods possibly characterized by persistently amplified wave patterns.

The North Atlantic Ocean Is in a State of Reduced Overturning

NASA Astrophysics Data System (ADS)

Smeed, D. A.; Josey, S. A.; Beaulieu, C.; Johns, W. E.; Moat, B. I.; Frajka-Williams, E.; Rayner, D.; Meinen, C. S.; Baringer, M. O.; Bryden, H. L.; McCarthy, G. D.

2018-02-01

The Atlantic Meridional Overturning Circulation (AMOC) is responsible for a variable and climatically important northward transport of heat. Using data from an array of instruments that span the Atlantic at 26°N, we show that the AMOC has been in a state of reduced overturning since 2008 as compared to 2004-2008. This change of AMOC state is concurrent with other changes in the North Atlantic such as a northward shift and broadening of the Gulf Stream and altered patterns of heat content and sea surface temperature. These changes resemble the response to a declining AMOC predicted by coupled climate models. Concurrent changes in air-sea fluxes close to the western boundary reveal that the changes in ocean heat transport and sea surface temperature have altered the pattern of ocean-atmosphere heat exchange over the North Atlantic. These results provide strong observational evidence that the AMOC is a major factor in decadal-scale variability of North Atlantic climate.

An approach to derive groundwater and stream threshold values for total nitrogen and ensure good ecological status of associated aquatic ecosystems - example from a coastal catchment to a vulnerable Danish estuary.

NASA Astrophysics Data System (ADS)

Hinsby, Klaus; Markager, Stiig; Kronvang, Brian; Windolf, Jørgen; Sonnenborg, Torben; Sørensen, Lærke

2015-04-01

Nitrate, which typically makes up the major part (~>90%) of dissolved inorganic nitrogen in groundwater and surface water, is the most frequent pollutant responsible for European groundwater bodies failing to meet the good status objectives of the European Water Framework Directive generally when comparing groundwater monitoring data with the nitrate quality standard of the Groundwater Directive (50 mg/l = the WHO drinking water standard). Still, while more than 50 % of the European surface water bodies do not meet the objective of good ecological status "only" 25 % of groundwater bodies do not meet the objective of good chemical status according to the river basin management plans reported by the EU member states. However, based on a study on interactions between groundwater, streams and a Danish estuary we argue that nitrate threshold values for aerobic groundwater often need to be significantly below the nitrate quality standard to ensure good ecological status of associated surface water bodies, and hence that the chemical status of European groundwater is worse than indicated by the present assessments. Here we suggest a methodology for derivation of groundwater and stream threshold values for total nitrogen ("nitrate") in a coastal catchment based on assessment of maximum acceptable nitrogen loadings (thresholds) to the associated vulnerable estuary. The applied method use existing information on agricultural practices and point source emissions in the catchment, groundwater, stream quantity and quality monitoring data that all feed data to an integrated groundwater and surface water modelling tool enabling us to conduct an assessment of total nitrogen loads and threshold concentrations derived to ensure/restore good ecological status of the investigated estuary. For the catchment to the Horsens estuary in Denmark we estimate the stream and groundwater thresholds for total nitrogen to be about 13 and 27 mg/l (~ 12 and 25 mg/l of nitrate). The shown example of deriving nitrogen threshold concentrations is for groundwater and streams in a coastal catchment discharging to a vulnerable estuary in Denmark, but the principles may be applied to large river basins with sub-catchments in several countries such as e.g. the Danube or the Rhine. In this case the relevant countries need to collaborate on derivation of nitrogen thresholds based on e.g. maximum acceptable nitrogen loadings to the Black Sea / the North Sea, and finally agree on thresholds for different parts of the river basin. Phosphorus is another nutrient which frequently results in or contributes to the eutrophication of surface waters. The transport and retention processes of total phosphorus (TP) is more complex than for nitrate (or alternatively total N), and presently we are able to establish TP thresholds for streams but not for groundwater. Derivation of TP thresholds is covered in an accompanying paper by Kronvang et al.

Quantitative evaluation of water bodies dynamic by means of thermal infrared and multispectral surveys on the Venetian lagoon

NASA Technical Reports Server (NTRS)

Alberotanza, L.; Lechi, G. M.

1977-01-01

Surveys employing a two channel Daedalus infrared scanner and multispectral photography were performed. The spring waning tide, the velocity of the water mass, and the types of suspended matter were among the topics studied. Temperature, salinity, sediment transport, and ebb stream velocity were recorded. The bottom topography was correlated with the dynamic characteristics of the sea surface.

Corresponding long-term shifts in stream temperature and invasive fish migration

USGS Publications Warehouse

McCann, Erin L.; Johnson, Nicholas; Pangle, Kevin

2018-01-01

By investigating historic trapping records of invasive sea lamprey (Petromyzon marinus) throughout tributaries to the Laurentian Great Lakes, we found that upstream spawning migration timing was highly correlated with stream temperatures over large spatial and temporal scales. Furthermore, several streams in our study exceeded a critical spring thermal threshold (i.e., 15°C) and experienced peak spawning migration up to 30 days earlier since the 1980s, whereas others were relatively unchanged. Streams exhibiting warming trends and earlier migration were spatially clustered and generally found on the leeward side of the Great Lakes where the lakes most affect local climate. These findings highlight that all streams are not equally impacted by climate change and represent, to our knowledge, the first observation linking long-term changes in stream temperatures to shifts in migration timing of an invasive fish. Earlier sea lamprey migration in Great Lakes tributaries may improve young of the year growth and survival, but not limit their spatial distribution, making sea lamprey control more challenging.

Developments in Earth observation for the assessment and monitoring of inland, transitional, coastal and shelf-sea waters.

PubMed

Tyler, Andrew N; Hunter, Peter D; Spyrakos, Evangelos; Groom, Steve; Constantinescu, Adriana Maria; Kitchen, Jonathan

2016-12-01

The Earth's surface waters are a fundamental resource and encompass a broad range of ecosystems that are core to global biogeochemical cycling and food and energy production. Despite this, the Earth's surface waters are impacted by multiple natural and anthropogenic pressures and drivers of environmental change. The complex interaction between physical, chemical and biological processes in surface waters poses significant challenges for in situ monitoring and assessment and often limits our ability to adequately capture the dynamics of aquatic systems and our understanding of their status, functioning and response to pressures. Here we explore the opportunities that Earth observation (EO) has to offer to basin-scale monitoring of water quality over the surface water continuum comprising inland, transition and coastal water bodies, with a particular focus on the Danube and Black Sea region. This review summarises the technological advances in EO and the opportunities that the next generation satellites offer for water quality monitoring. We provide an overview of algorithms for the retrieval of water quality parameters and demonstrate how such models have been used for the assessment and monitoring of inland, transitional, coastal and shelf-sea systems. Further, we argue that very few studies have investigated the connectivity between these systems especially in large river-sea systems such as the Danube-Black Sea. Subsequently, we describe current capability in operational processing of archive and near real-time satellite data. We conclude that while the operational use of satellites for the assessment and monitoring of surface waters is still developing for inland and coastal waters and more work is required on the development and validation of remote sensing algorithms for these optically complex waters, the potential that these data streams offer for developing an improved, potentially paradigm-shifting understanding of physical and biogeochemical processes across large scale river-sea systems including the Danube-Black Sea is considerable. Copyright © 2016. Published by Elsevier B.V.

Survival and metamorphosis of larval sea lamprey (Petromyzon marinus) residing in Lakes Michigan and Huron near river mouths

USGS Publications Warehouse

Johnson, Nicholas S.; Brenden, Travis O.; Swink, William D.; Lipps, Mathew A.

2016-01-01

Although population demographics of larval lampreys in streams have been studied extensively, demographics in lake environments have not. Here, we estimated survival and rates of metamorphosis for larval sea lamprey (Petromyzon marinus) populations residing in the Great Lakes near river mouths (hereafter termed lentic areas). Tagged larvae were stocked and a Bayesian multi-state tag-recovery model was used to investigate population parameters associated with tag recovery, including survival and metamorphosis probabilities. Compared to previous studies of larvae in streams, larval growth in lentic areas was substantially slower (Brody growth coefficient = 0.00132; estimate based on the recovery of six tagged larvae), survival was slightly greater (annual survival = 63%), and the length at which 50% of the larvae would be expected to metamorphose was substantially shorter (126 mm). Stochastic simulations were used to estimate the production of parasitic stage (juvenile) sea lamprey from a hypothetical population of larvae in a lentic environment. Production of juvenile sea lamprey was substantial because, even though larval growth in these environments was slow relative to stream environments, survival was high and length at metamorphosis was less. However, estimated production of juvenile sea lamprey was less for the lentic environment than for similar simulations for river environments where larvae grew faster. In circumstances where the cost to kill a larva with lampricide was equal and control funds are limited, sea lamprey control effort may be best directed toward larvae in streams with fast-growing larvae, because stream-produced larvae will most likely contribute to juvenile sea lamprey populations.

Coastal knickpoints and the competition between fluvial and wave-driven erosion on rocky coastlines

NASA Astrophysics Data System (ADS)

Limber, Patrick W.; Barnard, Patrick L.

2018-04-01

Active margin coastlines are distinguished by rock erosion that acts in two different directions: waves erode the coast horizontally or landwards, a process that creates sea cliffs; and rivers and streams erode the landscape vertically via channel incision. The relative rates of each process exert a dominant control on coastline morphology. Using a model of river channel incision and sea-cliff retreat, we explore how terrestrial and marine erosion compete to shape coastal topography, and specifically what conditions encourage the development of coastal knickpoints (i.e., a river or stream channels that end at a raised sea-cliff edge). We then compare results to actual landscapes. Model results and observations show that coastal knickpoint development is strongly dependent on drainage basin area, where knickpoints typically occur in drainage basins smaller than 5 × 105-6 × 106 m2, as well as channel geometry and sea-cliff retreat rate. In our study area, coastal knickpoints with persistent flow (waterfalls) are uncommon and form only within a small morphological window when 1) drainage basin area is large enough to sustain steady stream discharge, but not large enough to out-compete sea-cliff formation, 2) sea-cliff retreat is rapid, and 3) channel concavity is low so that channel slopes at the coast are high. This particular geomorphic combination can sustain sea-cliff formation even when streams tap into larger drainage basins with greater discharge and more stream power, and provides an initial explanation of why persistent coastal waterfalls are, along many coastlines, relatively rare features.

Coastal knickpoints and the competition between fluvial and wave-driven erosion on rocky coastlines

USGS Publications Warehouse

Limber, Patrick; Barnard, Patrick

2018-01-01

Active margin coastlines are distinguished by rock erosion that acts in two different directions: waves erode the coast horizontally or landwards, a process that creates sea cliffs; and rivers and streams erode the landscape vertically via channel incision. The relative rates of each process exert a dominant control on coastline morphology. Using a model of river channel incision and sea-cliff retreat, we explore how terrestrial and marine erosion compete to shape coastal topography, and specifically what conditions encourage the development of coastal knickpoints (i.e., a river or stream channels that end at a raised sea-cliff edge). We then compare results to actual landscapes. Model results and observations show that coastal knickpoint development is strongly dependent on drainage basin area, where knickpoints typically occur in drainage basins smaller than 5 × 105–6 × 106 m2, as well as channel geometry and sea-cliff retreat rate. In our study area, coastal knickpoints with persistent flow (waterfalls) are uncommon and form only within a small morphological window when 1) drainage basin area is large enough to sustain steady stream discharge, but not large enough to out-compete sea-cliff formation, 2) sea-cliff retreat is rapid, and 3) channel concavity is low so that channel slopes at the coast are high. This particular geomorphic combination can sustain sea-cliff formation even when streams tap into larger drainage basins with greater discharge and more stream power, and provides an initial explanation of why persistent coastal waterfalls are, along many coastlines, relatively rare features.

Modern foraminifera assemblages in the Amundsen Sea Embayment

NASA Astrophysics Data System (ADS)

Ewa Jernas, Patrycja; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Lander Rasmussen, Tine; Forwick, Matthias; Mackensen, Andreas; Schröder, Michael; Smith, James; Klages, Johann Philipp

2015-04-01

The West Antarctic Ice Sheet (WAIS) is considered the most unstable part of the Antarctic Ice Sheet. As the WAIS is mostly grounded below sea level, its stability is of great concern. A collapse of large parts of the WAIS would result in a significant global sea-level rise. At present, the WAIS shows dramatic ice loss in its Amundsen Sea sector, especially in Pine Island Bay. Pine Island Glacier (PIG) is characterised by fast flow, major thinning and rapid grounding-line retreat. Its mass los over recent decades is generally attributed to melting caused by the inflow of warm Circumpolar Deep Water (CDW). Future melting of PIG may result in a sea level tipping point, because it could trigger widespread collapse of the WAIS, especially when considering ongoing climate change. Our research project aims to establish proxies (integration of foraminifera, sediment properties and oceanographic data) for modern environmental conditions by analysing seafloor surface sediments along a transect from the glacier proximal settings to the middle-outer shelf in the eastern Amundsen Sea Embayment. These proxies will then be applied on sediment records spanning the Holocene back to the Last Glacial Maximum for reconstructing spatial and temporal variations of CDW upwelling and ice-ocean interactions during the past c. 23,000 years. We will present preliminary results from the analyses of ten short marine sediment cores (multi and box cores) collected during expeditions JR179 (2008) and ANT-XXVI/3 (2010) along a transect from inner Pine Island Bay to the middle-outer shelf part of the Abbot Palaeo-Ice Stream Trough at water depths ranging from 458 m (middle shelf) to 1444 m (inner shelf). The sediment cores are currently investigated for distribution patterns of planktonic and benthic foraminifera and grain-size distribution at 1 cm resolution. Core tops (0-10 cm) were stained with Rose Bengal for living benthic foraminifera investigations. The chronology of the cores will be based on 210Pb and calibrated 14C dates. First results reveal the presence of living benthic foraminifera in surface sediments of all investigated cores suggesting that modern seabed surfaces were recovered. Moreover, a core retrieved from a water depth of 793 m in the Abbot Palaeo-Ice Stream Trough shows particularly high abundances of planktonic foraminifera Neogloboquadrina pachyderma.

Meteorological conditions in a thinner Arctic sea ice regime from winter to summer during the Norwegian Young Sea Ice expedition (N-ICE2015)

NASA Astrophysics Data System (ADS)

Cohen, Lana; Hudson, Stephen R.; Walden, Von P.; Graham, Robert M.; Granskog, Mats A.

2017-07-01

Atmospheric measurements were made over Arctic sea ice north of Svalbard from winter to early summer (January-June) 2015 during the Norwegian Young Sea Ice (N-ICE2015) expedition. These measurements, which are available publicly, represent a comprehensive meteorological data set covering the seasonal transition in the Arctic Basin over the new, thinner sea ice regime. Winter was characterized by a succession of storms that produced short-lived (less than 48 h) temperature increases of 20 to 30 K at the surface. These storms were driven by the hemispheric scale circulation pattern with a large meridional component of the polar jet stream steering North Atlantic storms into the high Arctic. Nonstorm periods during winter were characterized by strong surface temperature inversions due to strong radiative cooling ("radiatively clear state"). The strength and depth of these inversions were similar to those during the Surface Heat Budget of the Arctic Ocean (SHEBA) campaign. In contrast, atmospheric profiles during the "opaquely cloudy state" were different to those from SHEBA due to differences in the synoptic conditions and location within the ice pack. Storm events observed during spring/summer were the result of synoptic systems located in the Barents Sea and the Arctic Basin rather than passing directly over N-ICE2015. These synoptic systems were driven by a large-scale circulation pattern typical of recent years, with an Arctic Dipole pattern developing during June. Surface temperatures became near-constant 0°C on 1 June marking the beginning of summer. Atmospheric profiles during the spring and early summer show persistent lifted temperature and moisture inversions that are indicative of clouds and cloud processes.

Interplay of grounding-line dynamics and sub-shelf melting during retreat of the Bjørnøyrenna Ice Stream.

PubMed

Petrini, Michele; Colleoni, Florence; Kirchner, Nina; Hughes, Anna L C; Camerlenghi, Angelo; Rebesco, Michele; Lucchi, Renata G; Forte, Emanuele; Colucci, Renato R; Noormets, Riko

2018-05-08

The Barents Sea Ice Sheet was a marine-based ice sheet, i.e., it rested on the Barents Sea floor during the Last Glacial Maximum (21 ky BP). The Bjørnøyrenna Ice Stream was the largest ice stream draining the Barents Sea Ice Sheet and is regarded as an analogue for contemporary ice streams in West Antarctica. Here, the retreat of the Bjørnøyrenna Ice Stream is simulated by means of two numerical ice sheet models and results assessed against geological data. We investigate the sensitivity of the ice stream to changes in ocean temperature and the impact of grounding-line physics on ice stream retreat. Our results suggest that the role played by sub-shelf melting depends on how the grounding-line physics is represented in the models. When an analytic constraint on the ice flux across the grounding line is applied, the retreat of Bjørnøyrenna Ice Stream is primarily driven by internal ice dynamics rather than by oceanic forcing. This suggests that implementations of grounding-line physics need to be carefully assessed when evaluating and predicting the response of contemporary marine-based ice sheets and individual ice streams to ongoing and future ocean warming.

Increased Internal Atmospheric Variability Contributed to the Persistence of the California Drought Through the 2015/16 El Niño

NASA Astrophysics Data System (ADS)

Zaiss, J.; Stott, L. D.; Buenning, N. H.

2017-12-01

The 2015/16 El Niño was one of the strongest on record and was expected to bring relief to the prolonged drought that had affected California for the previous four years. Virtually all seasonal forecast models predicted a wet winter over California, similar to the 1997/98 El Niño winter season. However, as the El Niño event came and went, the drought persisted through 2015/16. We are investigating why the 2015/16 El Niño winter was anomalous dry by conducting ensemble simulations using the atmospheric Global Spectral Model (GSM) forced with observed sea surface temperatures and sea ice concentration. Our results indicate increased variance in precipitation amounts compared to the 1997/98 El Niño, possibly suggesting an increase in atmospheric internal variability. Recent work has shown a possible role of declining Arctic sea ice in mid-latitude weather extremes through variations of the jet stream that could account for the increased precipitation variance. When Arctic sea ice concentrations are low, the jet stream tends to be wavier, slowing meanders that propagate storm systems towards the southwestern US. To investigate the role that sea ice decline played in prolonging the California drought and the observed change in precipitation variance, statistical analyses of metrological data together with ensemble simulations with GSM are used to evaluate differences between the 1997/98 and 2015/2016 El Niño events. We force GSM with 1997/98 SST anomalies but use the 2015/16 sea ice concentration. By doing so we quantify the effect of decreased sea ice concentration on the 2015/16 El Niño event wet season. These results not only elucidate how declining sea ice affected mid-latitude weather systems during the 2015/16 El Niño winter, they also contribute to the ongoing discussion about how declining sea ice may influence weather events and their predictability in the 21st century.

Measuring surface-water loss in Honouliuli Stream near the ‘Ewa Shaft, O‘ahu, Hawai‘i

USGS Publications Warehouse

Rosa, Sarah N.

2017-05-30

The Honolulu Board of Water Supply is currently concerned with the possibility of bacteria in the pumped water of the ‘Ewa Shaft (State well 3-2202-21). Groundwater from the ‘Ewa Shaft could potentially be used to meet future potable water needs in the ‘Ewa area on the island of O‘ahu. The source of the bacteria in the pumped water is unknown, although previous studies indicate that surface water may be lost to the subsurface near the site. The ‘Ewa Shaft consists of a vertical shaft, started near the south bank of Honouliuli Stream at an altitude of about 161 feet, and two horizontal infiltration tunnels near sea level. The shaft extracts groundwater from near the top of the freshwater lens in the Waipahu-Waiawa aquifer system within the greater Pearl Harbor Aquifer Sector, a designated Water Management Area.The surface-water losses were evaluated with continuous groundwater-level data from the ‘Ewa Shaft and a nearby monitoring well, continuous stream-discharge data from U.S. Geological Survey streamflow-gaging station 16212490 (Honouliuli Stream at H-1 Freeway near Waipahu), and seepage-run measurements in Honouliuli Stream and its tributary. During storms, discharge at the Honouliuli Stream gaging station increases and groundwater levels at ‘Ewa Shaft and a nearby monitoring well also increase. The concurrent increase in water levels at ‘Ewa Shaft and the nearby monitoring well during storms indicates that regional groundwater-level changes related to increased recharge, reduced withdrawals (due to a decrease in demand during periods of rainfall), or both may be occurring; although these data do not preclude the possibility of local recharge from Honouliuli Stream. Discharge measurements from two seepage runs indicate that surface water in the immediate area adjacent to ‘Ewa Shaft infiltrates into the streambed and may later reach the groundwater system developed by the ‘Ewa Shaft. The estimated seepage loss rates in the vicinity of ‘Ewa Shaft from the two seepage runs generally ranged from 0.27 to 1.78 million gallons per day per mile of stream reach; although higher seepage rates may occur during periods of higher discharge in Honouliuli Stream. A potential source of bacteria in ‘Ewa Shaft maybe related to seepage from Honouliuli Stream; however, other sources of bacteria were not studied and cannot be excluded.

Calcareous nannofossil evidence for the existence of the Gulf Stream during the late Maastrichtian

USGS Publications Warehouse

Watkins, D.K.; ,

2005-01-01

Upper Maastrichtian calcareous nannofossil assemblages, from eight cores on the South Carolina Coastal Plain (onshore set) and three deep sea drilling sites from the continental slope and abyssal hills (offshore set), were analyzed by correlation and principal component analysis to examine the ancient surface water thermal structure. In addition, a temperature index derived from independently published paleobiogeographic information was applied to the sample data. All three methods indicate a strong separation of the samples into onshore and offshore sets, with the offshore data set exhibiting significantly warmer paleotemperatures. The great disparity between these two sample sets indicates that there was a strong thermal contrast between the onshore and offshore surface water masses that persisted throughout the late Maastrichtian despite evident shortterm changes in fertility, productivity, and community structure. This suggests the Gulf Stream was present as a major oceanographic feature during the late Maastrichtian. Copyright 2005 by the American Geophysical Union.

High-resolution IP25-based reconstruction of sea-ice variability in the western North Pacific and Bering Sea during the past 18,000 years

NASA Astrophysics Data System (ADS)

Méheust, Marie; Stein, Ruediger; Fahl, Kirsten; Max, Lars; Riethdorf, Jan-Rainer

2016-04-01

Due to its strong influence on heat and moisture exchange between the ocean and the atmosphere, sea ice is an essential component of the global climate system. In the context of its alarming decrease in terms of concentration, thickness and duration, understanding the processes controlling sea-ice variability and reconstructing paleo-sea-ice extent in polar regions have become of great interest for the scientific community. In this study, for the first time, IP25, a recently developed biomarker sea-ice proxy, was used for a high-resolution reconstruction of the sea-ice extent and its variability in the western North Pacific and western Bering Sea during the past 18,000 years. To identify mechanisms controlling the sea-ice variability, IP25 data were associated with published sea-surface temperature as well as diatom and biogenic opal data. The results indicate that a seasonal sea-ice cover existed during cold periods (Heinrich Stadial 1 and Younger Dryas), whereas during warmer intervals (Bølling-Allerød and Holocene) reduced sea ice or ice-free conditions prevailed in the study area. The variability in sea-ice extent seems to be linked to climate anomalies and sea-level changes controlling the oceanographic circulation between the subarctic Pacific and the Bering Sea, especially the Alaskan Stream injection though the Aleutian passes.

TOPEX/El Nino Watch - El Nino Warm Water Pool Returns to Near Normal State, Mar, 14, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

Sperm whale long-range echolocation sounds revealed by ANTARES, a deep-sea neutrino telescope.

PubMed

André, M; Caballé, A; van der Schaar, M; Solsona, A; Houégnigan, L; Zaugg, S; Sánchez, A M; Castell, J V; Solé, M; Vila, F; Djokic, D; Adrián-Martínez, S; Albert, A; Anghinolfi, M; Anton, G; Ardid, M; Aubert, J-J; Avgitas, T; Baret, B; Barrios-Martí, J; Basa, S; Bertin, V; Biagi, S; Bormuth, R; Bouwhuis, M C; Bruijn, R; Brunner, J; Busto, J; Capone, A; Caramete, L; Carr, J; Celli, S; Chiarusi, T; Circella, M; Coleiro, A; Coniglione, R; Costantini, H; Coyle, P; Creusot, A; Deschamps, A; De Bonis, G; Distefano, C; Di Palma, I; Donzaud, C; Dornic, D; Drouhin, D; Eberl, T; El Bojaddaini, I; Elsässer, D; Enzenhöfer, A; Fehn, K; Felis, I; Fusco, L A; Galatà, S; Gay, P; Geißelsöder, S; Geyer, K; Giordano, V; Gleixner, A; Glotin, H; Gracia-Ruiz, R; Graf, K; Hallmann, S; van Haren, H; Heijboer, A J; Hello, Y; Hernandez-Rey, J J; Hößl, J; Hofestädt, J; Hugon, C; Illuminati, G; James, C W; de Jong, M; Jongen, M; Kadler, M; Kalekin, O; Katz, U; Kießling, D; Kouchner, A; Kreter, M; Kreykenbohm, I; Kulikovskiy, V; Lachaud, C; Lahmann, R; Lefèvre, D; Leonora, E; Loucatos, S; Marcelin, M; Margiotta, A; Marinelli, A; Martínez-Mora, J A; Mathieu, A; Melis, K; Michael, T; Migliozzi, P; Moussa, A; Mueller, C; Nezri, E; Păvălaş, G E; Pellegrino, C; Perrina, C; Piattelli, P; Popa, V; Pradier, T; Racca, C; Riccobene, G; Roensch, K; Saldaña, M; Samtleben, D F E; Sanguineti, M; Sapienza, P; Schnabel, J; Schüssler, F; Seitz, T; Sieger, C; Spurio, M; Stolarczyk, Th; Sánchez-Losa, A; Taiuti, M; Trovato, A; Tselengidou, M; Turpin, D; Tönnis, C; Vallage, B; Vallée, C; Van Elewyck, V; Vivolo, D; Wagner, S; Wilms, J; Zornoza, J D; Zuñiga, J

2017-04-12

Despite dedicated research has been carried out to adequately map the distribution of the sperm whale in the Mediterranean Sea, unlike other regions of the world, the species population status is still presently uncertain. The analysis of two years of continuous acoustic data provided by the ANTARES neutrino telescope revealed the year-round presence of sperm whales in the Ligurian Sea, probably associated with the availability of cephalopods in the region. The presence of the Ligurian Sea sperm whales was demonstrated through the real-time analysis of audio data streamed from a cabled-to-shore deep-sea observatory that allowed the hourly tracking of their long-range echolocation behaviour on the Internet. Interestingly, the same acoustic analysis indicated that the occurrence of surface shipping noise would apparently not condition the foraging behaviour of the sperm whale in the area, since shipping noise was almost always present when sperm whales were acoustically detected. The continuous presence of the sperm whale in the region confirms the ecological value of the Ligurian sea and the importance of ANTARES to help monitoring its ecosystems.

Sperm whale long-range echolocation sounds revealed by ANTARES, a deep-sea neutrino telescope

NASA Astrophysics Data System (ADS)

André, M.; Caballé, A.; van der Schaar, M.; Solsona, A.; Houégnigan, L.; Zaugg, S.; Sánchez, A. M.; Castell, J. V.; Solé, M.; Vila, F.; Djokic, D.; Adrián-Martínez, S.; Albert, A.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; de Bonis, G.; Distefano, C.; di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Fehn, K.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernandez-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Riccobene, G.; Roensch, K.; Saldaña, M.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Sánchez-Losa, A.; Taiuti, M.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; van Elewyck, V.; Vivolo, D.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zuñiga, J.

2017-04-01

Despite dedicated research has been carried out to adequately map the distribution of the sperm whale in the Mediterranean Sea, unlike other regions of the world, the species population status is still presently uncertain. The analysis of two years of continuous acoustic data provided by the ANTARES neutrino telescope revealed the year-round presence of sperm whales in the Ligurian Sea, probably associated with the availability of cephalopods in the region. The presence of the Ligurian Sea sperm whales was demonstrated through the real-time analysis of audio data streamed from a cabled-to-shore deep-sea observatory that allowed the hourly tracking of their long-range echolocation behaviour on the Internet. Interestingly, the same acoustic analysis indicated that the occurrence of surface shipping noise would apparently not condition the foraging behaviour of the sperm whale in the area, since shipping noise was almost always present when sperm whales were acoustically detected. The continuous presence of the sperm whale in the region confirms the ecological value of the Ligurian sea and the importance of ANTARES to help monitoring its ecosystems.

Sperm whale long-range echolocation sounds revealed by ANTARES, a deep-sea neutrino telescope

PubMed Central

André, M.; Caballé, A.; van der Schaar, M.; Solsona, A.; Houégnigan, L.; Zaugg, S.; Sánchez, A. M.; Castell, J. V.; Solé, M.; Vila, F.; Djokic, D.; Adrián-Martínez, S.; Albert, A.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Fehn, K.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernandez-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Racca, C.; Riccobene, G.; Roensch, K.; Saldaña, M.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Sánchez-Losa, A.; Taiuti, M.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vivolo, D.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zuñiga, J.

2017-01-01

Despite dedicated research has been carried out to adequately map the distribution of the sperm whale in the Mediterranean Sea, unlike other regions of the world, the species population status is still presently uncertain. The analysis of two years of continuous acoustic data provided by the ANTARES neutrino telescope revealed the year-round presence of sperm whales in the Ligurian Sea, probably associated with the availability of cephalopods in the region. The presence of the Ligurian Sea sperm whales was demonstrated through the real-time analysis of audio data streamed from a cabled-to-shore deep-sea observatory that allowed the hourly tracking of their long-range echolocation behaviour on the Internet. Interestingly, the same acoustic analysis indicated that the occurrence of surface shipping noise would apparently not condition the foraging behaviour of the sperm whale in the area, since shipping noise was almost always present when sperm whales were acoustically detected. The continuous presence of the sperm whale in the region confirms the ecological value of the Ligurian sea and the importance of ANTARES to help monitoring its ecosystems. PMID:28401960

The effect of the lamprey larvicide, 3-trifluormethyl-4-nitrophenol, on selected aquatic invertebrates

USGS Publications Warehouse

Smith, Allen J.

1967-01-01

The chemical compound 3-trifluoromethyl-4-nitrophenol (TFM) is used to control the sea lamprey (Petromyzon marinus) in the upper Great Lakes. It is introduced into streams in which sea lampreys have spawned, to kill the larvae. These 'treatments' are carried out at intervals shorter than the larval phase of the sea lamprey's life cycle (about 4 to 7 years) to prevent movement of the metamorphosed parasitic lampreys into the lakes. Most of the streams which contain sea lamprey larvae also have valuable resident fish or serve as spawning and nursery areas for fish of the Great Lakes. These species must be protected from both the direct toxic effects of the control method and from indirect effects such as destruction of food supplies. Studies have shown that TFM is nontoxic to most species of fish when used at the concentrations that kill larval lampreys. Information on the effect of TFM on aquatic invertebrates is meager. Applegate et al. reported that TFM was not harmful to selected invertebrates which they included in simulated stream tests. They also stated that no harmful effects to invertebrates were observed during actual stream application. The variety of invertebrate species used in simulated stream tests was limited, and close observation of invertebrates under stream conditions is difficult. Therefore, the present laboratory bioassays were conducted to determine the toxicity of TFM to representatives of a number of groups of invertebrates.

River plumes investigation using Sentinel-2A MSI and Landsat-8 OLI data

NASA Astrophysics Data System (ADS)

Lavrova, Olga Yu.; Soloviev, Dmitry M.; Strochkov, Mikhail A.; Bocharova, Tatiana Y.; Kashnitsky, Alexandr V.

2016-10-01

We present the results of using Sentinel-2A Multispectral Imager Instrument (MSI/S2) and Landsat-8 Operational Land Imager (OLI/L8) data to monitor river plumes in the eastern Black Sea and from the Rhône River in the Mediterranean Sea. The focus is on exploring the possibility to investigate hydrodynamic processes associated with river outflows, in particular internal waves (IWs). Submesoscale IWs having wavelengths less than 50 m and generated by unstable sharp front of a river plume were revealed and their parameters were assessed. A map of surface manifestation of IW trains in the Gulf of Lions was created based on MSI/S2 images. There are different mechanisms of IW generation in river outflow zones, they are determined by a number of parameters including river discharge, bottom topography and presence of tidal currents or inertial period IWs in the shelf zone. A new phenomenon manifested as a chain of quasi circles was discovered. Inertial water motions were suggested as its prime cause, however, this hypothesis is yet to be investigated. An analysis of OLI/L8 and MSI/S2 data enabled us to consider in detail river debouchment streams. For the first time a wave pattern of such stream in the eastern Black Sea was observed in conditions of foehn winds. Usually, foehn winds are distinctly manifested in radar images. A joint analysis of quasi simultaneous ocean color MSI/S2 and Sentinel-1A SAR images demonstrated how water stream wave-like signatures differ from those of foehn winds.

MODIS Global Sea Surface Temperature

NASA Technical Reports Server (NTRS)

2002-01-01

Every day the Moderate-resolution Imaging Spectroradiometer (MODIS) measures sea surface temperature over the entire globe with high accuracy. This false-color image shows a one-month composite for May 2001. Red and yellow indicates warmer temperatures, green is an intermediate value, while blues and then purples are progressively colder values. The new MODIS sea surface temperature product will be particularly useful in studies of temperature anomalies, such as El Nino, as well as research into how air-sea interactions drive changes in weather and climate patterns. In the high resolution image, notice the amazing detail in some of the regional current patterns. For instance, notice the cold water currents that move from Antarctica northward along South America's west coast. These cold, deep waters upwell along an equatorial swath around and to the west of the Galapagos Islands. Note the warm, wide currents of the Gulf Stream moving up the United States' east coast, carrying Caribbean warmth toward Newfoundland and across the Atlantic toward Western Europe. Note the warm tongue of water extending from Africa's east coast to well south of the Cape of Good Hope. MODIS was launched in December 1999 aboard NASA's Terra satellite. For more details on this and other MODIS data products, please see NASA Unveils Spectacular Suite of New Global Data Products from MODIS. Image courtesy MODIS Ocean Group, NASA GSFC, and the University of Miami

A synthesized mating pheromone component increases adult sea lamprey (Petromyzon marinus) trap capture in management scenarios

USGS Publications Warehouse

Johnson, Nicholas S.; Siefkes, Michael J.; Wagner, C. Michael; Dawson, Heather; Wang, Huiyong; Steeves, Todd; Twohey, Michael; Li, Weiming

2013-01-01

Application of chemical cues to manipulate adult sea lamprey (Petromyzon marinus) behavior is among the options considered for new sea lamprey control techniques in the Laurentian Great Lakes. A male mating pheromone component, 7a,12a,24-trihydroxy-3-one-5a-cholan-24-sulfate (3kPZS), lures ovulated female sea lamprey upstream into baited traps in experimental contexts with no odorant competition. A critical knowledge gap is whether this single pheromone component influences adult sea lamprey behavior in management contexts containing free-ranging sea lampreys. A solution of 3kPZS to reach a final in-stream concentration of 10-12 mol·L-1 was applied to eight Michigan streams at existing sea lamprey traps over 3 years, and catch rates were compared between paired 3kPZS-baited and unbaited traps. 3kPZS-baited traps captured significantly more sexually immature and mature sea lampreys, and overall yearly trapping efficiency within a stream averaged 10% higher during years when 3kPZS was applied. Video analysis of a trap funnel showed that the likelihood of sea lamprey trap entry after trap encounter was higher when the trap was 3kPZS baited. Our approach serves as a model for the development of similar control tools for sea lamprey and other aquatic invaders.

How the wet side of NOAA (NMFS and NOS) is using JPSS data

NASA Astrophysics Data System (ADS)

Wilson, C.

2016-12-01

The VIIRS (Visible Infrared Imaging Radiometer Suite) instrument on the JPSS satellite, launched in 2011, is the most recent of a series of US ocean-color satellite measurements. With the launch of VIIRS we now have a nineteen-year continuous time-series of ocean-color measurements, starting with SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), launched in 1997, and followed by MODIS (Moderate Resolution Imaging Spectroradiometer) on the Aqua satellite that was launched in 2002. What is significant about the VIIRS launch is that it represents a transition from ocean-color satellite data being generated from research missions launched by NASA to an operational data-stream that NOAA has responsibility for. In this presentation I will present a broad array of projects that will demonstrate how NOS (National Ocean Service) and NMFS (National Marine Fisheries Service) are using VIIRS data, both ocean-color and sea-surface temperature. Since fisheries and ecosystems studies typically require long time series, on the order of years to decades, the utility of the VIIRS data is that it has been intercalibrated with legacy data-streams to provide a climate data record. The majority of the projects highlighted were developed as part of the NOAA ocean satellite course that has been conducted annually since 2005.

Nearshore morphology and late Quaternary geologic framework of the northern Monterey Bay Marine Sanctuary, California

USGS Publications Warehouse

Anima, R.J.; Eittreim, S.L.; Edwards, B.D.; Stevenson, A.J.

2002-01-01

A combination of side-scanning sonar and high-resolution seismic reflection data image seafloor bedrock exposures and erosional features across the nearshore shelf. Sediment-filled troughs incise the inner shelf rock exposures and tie directly to modern coastal streams. The resulting bedrock geometry can be related to its resistance to erosion. Comparison of the depth of the transgressive erosional surface to recently developed sea level curves suggests a period of slow sea level rise during the early stages of post-interglacial marine transgression. The slow rise of sea level suggests an erosional episode that limited the preservation of buried paleo-channels beyond 70 m water depth. Seafloor features suggest that localized faulting in the area may have influenced the morphology of bedrock exposures and the coastline. ?? 2002 Elsevier Science B.V. All rights reserved.

Lateral and vertical distribution of downstream migrating juvenile sea lamprey

USGS Publications Warehouse

Sotola, V. Alex; Miehls, Scott M.; Simard, Lee G.; Marsden, J. Ellen

2018-01-01

Sea lamprey is considered an invasive and nuisance species in the Laurentian Great Lakes, Lake Champlain, and the Finger Lakes of New York and is a major focus of control efforts. Currently, management practices focus on limiting the area of infestation using barriers to block migratory adults, and lampricides to kill ammocoetes in infested tributaries. No control efforts currently target the downstream-migrating post-metamorphic life stage which could provide another management opportunity. In order to apply control methods to this life stage, a better understanding of their downstream movement patterns is needed. To quantify spatial distribution of downstream migrants, we deployed fyke and drift nets laterally and vertically across the stream channel in two tributaries of Lake Champlain. Sea lamprey was not randomly distributed across the stream width and lateral distribution showed a significant association with discharge. Results indicated that juvenile sea lamprey is most likely to be present in the thalweg and at midwater depths of the stream channel. Further, a majority of the catch occurred during high flow events, suggesting an increase in downstream movement activity when water levels are higher than base flow. Discharge and flow are strong predictors of the distribution of out-migrating sea lamprey, thus managers will need to either target capture efforts in high discharge areas of streams or develop means to guide sea lamprey away from these areas.

The Gulf Stream frontal system: A key oceanographic feature in the habitat selection of the leatherback turtle?

NASA Astrophysics Data System (ADS)

Chambault, Philippine; Roquet, Fabien; Benhamou, Simon; Baudena, Alberto; Pauthenet, Etienne; de Thoisy, Benoît; Bonola, Marc; Dos Reis, Virginie; Crasson, Rodrigue; Brucker, Mathieu; Le Maho, Yvon; Chevallier, Damien

2017-05-01

Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. The importance of the Gulf Stream frontal system in the selection of high residence time (HRT) areas by the North Atlantic leatherback turtle is assessed here for the first time using state-of-the-art ocean reanalysis products. Ten adult females from the Eastern French Guianese rookery were satellite tracked during post-nesting migration to relate (1) their horizontal movements to physical gradients (Sea Surface Temperature (SST), Sea Surface Height (SSH) and filaments) and biological variables (micronekton and chlorophyll a), and (2) their diving behaviour to vertical structures within the water column (mixed layer, thermocline, halocline and nutricline). All the turtles migrated northward towards the Gulf Stream north wall. Although their HRT areas were geographically remote (spread between 80-30 °W and 28-45 °N), all the turtles targeted similar habitats in terms of physical structures, i.e. strong gradients of SST, SSH and a deep mixed layer. This close association with the Gulf Stream frontal system highlights the first substantial synchronization ever observed in this species, as the HRTs were observed in close match with the autumn phytoplankton bloom. Turtles remained within the enriched mixed layer at depths of 38.5±7.9 m when diving in HRT areas, likely to have an easier access to their prey and maximize therefore the energy gain. These depths were shallow in comparison to those attained within the thermocline (82.4±5.6 m) while crossing the nutrient-poor subtropical gyre, probably to reach cooler temperatures and save energy during the transit. In a context of climate change, anticipating the evolution of such frontal structure under the influence of global warming is crucial to ensure the conservation of this vulnerable species.

Distribution and abundance of anadromous Sea Lamprey Spawners in a fragmented stream: Current status and potential range expansion following barrier removal

USGS Publications Warehouse

Zydlewski, Joseph D.; Gardner, Cory; Coghlan, Stephen M.

2012-01-01

Dams fragment watersheds and prevent anadromous fishes from reaching historic spawning habitat. Sedgeunkedunk Stream, a small tributary to the Penobscot River (Maine), has been the focus of efforts to reestablish marine-freshwater connectivity and restore anadromous fishes via the removal of two barriers to fish migration. Currently, Petromyzon marinus (Sea Lamprey) is the only anadromous fish known to spawn successfully in the stream downstream of the lowermost dam. Here, we describe the distribution and abundance of a spawning population of Sea Lamprey in Sedgeunkedunk Stream, prior to and in anticipation of habitat increase after the completion of one barrier removal. In 2008, we estimated the abundance of Sea Lamprey and its nests using daily stream surveys and an open-population mark-recapture model. We captured 47 Sea Lamprey and implanted each with a PIT tag so that we could track movements and nest associations of individual fish. The spawning migration began on 18 June, and the last living individual was observed on 27 June. We located 31 nests, distributed from head-of-tide to the lowermost dam; no spawners or nests were observed in the tidally influenced zone or upstream of this dam. Mean longevity in the stream and the number of nests attended were correlated with arrival date; early migrants were alive longer and attended more nests than later migrants. Males were more likely to be observed away from a nest, or attending three or more nests, than were females, which attended usually one or two nests. We observed a negative association between nest abundance and substrate cover by fine sediment. Based on their observed movements in the system, and the extent of their habitat use, we anticipate that spawning Sea Lamprey will recolonize formerly inaccessible habitat after dam removals.

Initial results from geophysical surveys and shallow coring of the Northeast Greenland Ice Stream (NEGIS)

NASA Astrophysics Data System (ADS)

Vallelonga, P.; Christianson, K.; Alley, R. B.; Anandakrishnan, S.; Christian, J. E. M.; Dahl-Jensen, D.; Gkinis, V.; Holme, C.; Jacobel, R. W.; Karlsson, N. B.; Keisling, B. A.; Kipfstuhl, S.; Kjær, H. A.; Kristensen, M. E. L.; Muto, A.; Peters, L. E.; Popp, T.; Riverman, K. L.; Svensson, A. M.; Tibuleac, C.; Vinther, B. M.; Weng, Y.; Winstrup, M.

2014-07-01

The Northeast Greenland Ice Stream (NEGIS) is the sole interior Greenlandic ice stream. Fast flow initiates near the summit dome, and the ice stream terminates approximately 1000 km downstream in three large outlet glaciers that calve into the Greenland Sea. To better understand this important system, in the summer of 2012 we drilled a 67 m firn core and conducted ground-based radio-echo sounding (RES) and active-source seismic surveys at a site approximately 150 km downstream from the onset of streaming flow (NEGIS firn core, 75°37.61' N, 35°56.49' W). The site is representative of the upper part of the ice stream, while also being in a crevasse-free area for safe surface operations. Annual cycles were observed for insoluble dust, sodium and ammonium concentrations and for electrolytic conductivity, allowing a seasonally resolved chronology covering the past 400 yr. Annual layer thicknesses averaged 0.11 m ice equivalent (i.e.) for the period 1607-2011, although accumulation varied between 0.08 and 0.14 m i.e., likely due to flow-related changes in surface topography. Tracing of RES layers from the NGRIP (North Greenland Ice Core Project) ice core site shows that the ice at NEGIS preserves a climatic record of at least the past 51 kyr. We demonstrate that deep ice core drilling in this location can provide a reliable Holocene and late-glacial climate record, as well as helping to constrain the past dynamics and ice-lithosphere interactions of the Greenland Ice Sheet.

Initial results from geophysical surveys and shallow coring of the Northeast Greenland Ice Stream (NEGIS)

NASA Astrophysics Data System (ADS)

Vallelonga, P.; Christianson, K.; Alley, R. B.; Anandakrishnan, S.; Christian, J. E. M.; Dahl-Jensen, D.; Gkinis, V.; Holme, C.; Jacobel, R. W.; Karlsson, N.; Keisling, B. A.; Kipfstuhl, S.; Kjær, H. A.; Kristensen, M. E. L.; Muto, A.; Peters, L. E.; Popp, T.; Riverman, K. L.; Svensson, A. M.; Tibuleac, C.; Vinther, B. M.; Weng, Y.; Winstrup, M.

2014-01-01

The Northeast Greenland Ice Stream (NEGIS) is the sole interior Greenlandic ice stream. Fast flow initiates near the summit dome, and the ice stream terminates approximately 1000 km downstream in three large outlet glaciers that calve into the Greenland Sea. To better understand this important system, in the summer of 2012 we drilled a 67 m firn core and conducted ground-based radio-echo sounding (RES) and active-source seismic surveys at a site approximately 150 km downstream from the onset of streaming flow (NEGIS firn core, 75° 37.61' N, 35°56.49' W). The site is representative of the upper part of the ice stream, while also being in a crevasse-free area for safe surface operations. Annual cycles were observed for insoluble dust, sodium and ammonium concentrations and for electrolytic conductivity, allowing a seasonally resolved chronology covering the past 400 yr. Annual layer thicknesses averaged 0.11 m ice equivalent (i.e.) for the period 1607-2011, although accumulation varied between 0.08 and 0.14 m i.e., likely due to flow-related changes in surface topography. Tracing of RES layers from the NGRIP ice core site shows that the ice at NEGIS preserves a climatic record of at least the past 51 kyr. We demonstrate that a deep ice core drilling in this location can provide a reliable Holocene and late-glacial climate record, as well as helping to constrain the past dynamics and ice-lithosphere interactions of the Greenland Ice Sheet.

Alburnoides manyasensis (Actinopterygii, Cyprinidae), a new species of cyprinid fish from Manyas Lake basin, Turkey

PubMed Central

Turan, Davut; Ekmekçi, F. Güler; Kaya, Cüneyt; Güçlü, S. Serkan

2013-01-01

Abstract Alburnoides manyasensis, sp. n., is described from the Koca Stream (Lake Manyas drainage, Marmara Sea basin) in Anatolia. It is distinguished from all species of Alburnoides in Turkey and adjacent regions, Alburnoides tzanevi (Rezovska [Rezve], Istranca and Terkos streams in the western Black Sea drainage), Alburnoides cf. smyrnae (Banaz Stream, a drainage of Büyük Menderes River, Aegean Sea basin), Alburnoides fasciatus (streams and rivers in the eastern Black Sea drainage) and Alburnoides eichwaldii (Kura and Aras rivers [a drainage of Kura River], Caspian Sea basin) by a combination of the following characters (none unique to the species):marked hump at nape, especially in specimens larger than 60 mm SL; partly developed ventral keel between pelvic fin and anal fin, scaleless 1/2 to 2/3 its length; body depth at dorsal-fin origin 29−32% SL; caudal peduncle depth 11−12% SL; 45–52+ 2–3 lateral-line scales; 9–12 scale rows between lateral line and dorsal-fin origin; 4–5 scale rows between lateral line and anal-fin origin, 10½–12½ branched anal-fin rays; 40–42 total vertebrae. PMID:23794819

New aerogeophysical data reveal the extent of the Weddell Sea Rift beneath the Institute and Möller ice streams

NASA Astrophysics Data System (ADS)

Jordan, T. A.; Ferraccioli, F.; Siegert, M. J.; Ross, N.; Corr, H.; Bingham, R. G.; Rippin, D. M.; Le Brocq, A. M.

2011-12-01

Significant continental rifting associated with Gondwana breakup has been widely recognised in the Weddell Sea region. However, plate reconstructions and the extent of this rift system onshore beneath the West Antarctic Ice Sheet (WAIS) are ambiguous, due to the paucity of modern geophysical data across the Institute and Möller ice stream catchments. Understanding this region is key to unravelling Gondwana breakup and the possible kinematic links between the Weddell Sea and the West Antarctic Rift System. The nature of the underlying tectonic structure is also critical, as it provides the template for ice-flow draining ~20% of the West Antarctic Ice Sheet (WAIS). During the 2010/11 Antarctic field season ~25,000 km of new airborne radar, aerogravity and aeromagnetic data were collected to help unveil the crustal structure and geological boundary conditions beneath the Institute and Möller ice streams. Our new potential field maps delineate varied subglacial geology beneath the glacial catchments, including Jurassic intrusive rocks, sedimentary basins, and Precambrian basement rocks of the Ellsworth Mountains. Inversion of airborne gravity data reveal significant crustal thinning directly beneath the faster flowing coastal parts of the Institute and Möller ice streams. We suggest that continental rifting focussed along the Weddell Sea margin of the Ellsworth-Whitmore Mountains block, providing geological controls for the fast flowing ice streams of the Weddell Sea Embayment. Further to the south we suggest that strike-slip motion between the East Antarctica and the Ellsworth-Whitmore Mountains block may provide a kinematic link between Cretaceous-Cenozoic extension in the West Antarctic Rift System and deformation in the Weddell Sea Embayment.

TOPEX/El Nino Watch - La Nina Conditions Likely to Prevail, October 10, 1999

NASA Technical Reports Server (NTRS)

1999-01-01

A repeat of last year's mild La Nina conditions -- with a stormy winter in the Pacific Northwest and a dry winter in the southwestern United States -- will be the likely outcome of sea-surface heights observed by NASA's TOPEX/Poseidon satellite, scientists say.

TOPEX/Poseidon has detected lower than normal sea-surface heights in the eastern North Pacific and unusually high sea-surface heights in the western and mid-latitude Pacific. The height of the sea surface over a given area is an indicator of ocean temperature and other factors that influence climate.

The latest measurements, taken during a 10-day data cycle October 5-15, are available at http://www.jpl.nasa.gov/elnino . Sea-surface height is shown relative to normal (green) and reveals cooler water (blue and purple) measuring about 14 centimeters (6 inches) lower in the eastern North Pacific, from the Gulf of Alaska to central Alaska, and along the equator. The cooling trend sets the stage for another La Nina this winter.

'A mirror image of that oceanic profile prevails in the western and mid-latitude Pacific Ocean, where higher than normal sea-surface heights (red and white) are currently about 20 centimeters or 8 inches. Unusually warm temperatures (shown in red and white) have persisted and topped last year's temperatures,' said Dr. William Patzert, an oceanographer at NASA's Jet Propulsion Laboratory, Pasadena, CA.

'These unbalanced conditions will undoubtedly exert a very strong influence on climate over North America this fall and winter,' Patzert said. 'Our profile of high sea-surface heights and warm temperatures in the western Pacific Ocean contrasts with low sea-surface heights and cool conditions in the eastern and equatorial Pacific. Those conditions will have a powerful impact on the weather system delivering jet streams out of the North Pacific.'

Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California and the Southwest, the data show. 'Clearly, these unusual conditions, which have persisted for 2 1/2 years, will not be returning to normal any time soon,' Patzert said. 'This climate imbalance is big and we're definitely going through a decade of wild climatic behavior. But when we look back at the climate record over the past century, we've seen behavior like this before.'

The TOPEX/Poseidon satellite's measurements have provided scientists with a detailed view of the 1997-1999 El Nino/La Nina climate pattern by measuring the changing sea-surface height with unprecedented precision.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Reconciling records of ice streaming and ice margin retreat to produce a palaeogeographic reconstruction of the deglaciation of the Laurentide Ice Sheet

NASA Astrophysics Data System (ADS)

Margold, Martin; Stokes, Chris R.; Clark, Chris D.

2018-06-01

This paper reconstructs the deglaciation of the Laurentide Ice Sheet (LIS; including the Innuitian Ice Sheet) from the Last Glacial Maximum (LGM), with a particular focus on the spatial and temporal variations in ice streaming and the associated changes in flow patterns and ice divides. We build on a recent inventory of Laurentide ice streams and use an existing ice margin chronology to produce the first detailed transient reconstruction of the ice stream drainage network in the LIS, which we depict in a series of palaeogeographic maps. Results show that the drainage network at the LGM was similar to modern-day Antarctica. The majority of the ice streams were marine terminating and topographically-controlled and many of these continued to function late into the deglaciation, until the ice sheet lost its marine margin. Ice streams with a terrestrial ice margin in the west and south were more transient and ice flow directions changed with the build-up, peak-phase and collapse of the Cordilleran-Laurentide ice saddle. The south-eastern marine margin in Atlantic Canada started to retreat relatively early and some of the ice streams in this region switched off at or shortly after the LGM. In contrast, the ice streams draining towards the north-western and north-eastern marine margins in the Beaufort Sea and in Baffin Bay appear to have remained stable throughout most of the Late Glacial, and some of them continued to function until after the Younger Dryas (YD). The YD influenced the dynamics of the deglaciation, but there remains uncertainty about the response of the ice sheet in several sectors. We tentatively ascribe the switching-on of some major ice streams during this period (e.g. M'Clintock Channel Ice Stream at the north-west margin), but for other large ice streams whose timing partially overlaps with the YD, the drivers are less clear and ice-dynamical processes, rather than effects of climate and surface mass balance are viewed as more likely drivers. Retreat rates markedly increased after the YD and the ice sheet became limited to the Canadian Shield. This hard-bed substrate brought a change in the character of ice streaming, which became less frequent but generated much broader terrestrial ice streams. The final collapse of the ice sheet saw a series of small ephemeral ice streams that resulted from the rapidly changing ice sheet geometry in and around Hudson Bay. Our reconstruction indicates that the LIS underwent a transition from a topographically-controlled ice drainage network at the LGM to an ice drainage network characterised by less frequent, broad ice streams during the later stages of deglaciation. These deglacial ice streams are mostly interpreted as a reaction to localised ice-dynamical forcing (flotation and calving of the ice front in glacial lakes and transgressing sea; basal de-coupling due to large amount of meltwater reaching the bed, debuttressing due to rapid changes in ice sheet geometry) rather than as conveyors of excess mass from the accumulation area of the ice sheet. At an ice sheet scale, the ice stream drainage network became less widespread and less efficient with the decreasing size of the deglaciating ice sheet, the final elimination of which was mostly driven by surface melt.

Bubbles in Titan’s Seas: Nucleation, Growth, and RADAR Signature

NASA Astrophysics Data System (ADS)

Cordier, Daniel; Liger-Belair, Gérard

2018-05-01

In the polar regions of Titan, the main satellite of Saturn, hydrocarbon seas have been discovered by the Cassini–Huygens mission. RADAR observations have revealed surprising and transient bright areas over the Ligeia Mare surface. As suggested by recent research, bubbles could explain these strange features. However, the nucleation and growth of such bubbles, together with their RADAR reflectivity, have never been investigated. All of these aspects are critical to an actual observation. We have thus applied the classical nucleation theory to our context, and we developed a specific radiative transfer model that is appropriate for bubble streams in cryogenic liquids. According to our results, the sea bed appears to be the most plausible place for the generation of bubbles, leading to a signal comparable to observations. This conclusion is supported by thermodynamic arguments and by RADAR properties of a bubbly column. The latter are also valid in the case of bubble plumes, due to gas leaking from the sea floor.

Prediction of phosphorus loads in an artificially drained lowland catchment using a modified SWAT model

NASA Astrophysics Data System (ADS)

Bauwe, Andreas; Eckhardt, Kai-Uwe; Lennartz, Bernd

2017-04-01

Eutrophication is still one of the main environmental problems in the Baltic Sea. Currently, agricultural diffuse sources constitute the major portion of phosphorus (P) fluxes to the Baltic Sea and have to be reduced to achieve the HELCOM targets and improve the ecological status. Eco-hydrological models are suitable tools to identify sources of nutrients and possible measures aiming at reducing nutrient loads into surface waters. In this study, the Soil and Water Assessment Tool (SWAT) was applied to the Warnow river basin (3300 km2), the second largest watershed in Germany discharging into the Baltic Sea. The Warnow river basin is located in northeastern Germany and characterized by lowlands with a high proportion of artificially drained areas. The aim of this study were (i) to estimate P loadings for individual flow fractions (point sources, surface runoff, tile flow, groundwater flow), spatially distributed on sub-basin scale. Since the official version of SWAT does not allow for the modeling of P in tile drains, we tested (ii) two different approaches of simulating P in tile drains by changing the SWAT source code. The SWAT source code was modified so that (i) the soluble P concentration of the groundwater was transferred to the tile water and (ii) the soluble P in the soil was transferred to the tiles. The SWAT model was first calibrated (2002-2011) and validated (1992-2001) for stream flow at 7 headwater catchments at a daily time scale. Based on this, the stream flow at the outlet of the Warnow river basin was simulated. Performance statistics indicated at least satisfactory model results for each sub-basin. Breaking down the discharge into flow constituents, it becomes visible that stream flow is mainly governed by groundwater and tile flow. Due to the topographic situation with gentle slopes, surface runoff played only a minor role. Results further indicate that the prediction of soluble P loads was improved by the modified SWAT versions. Major sources of P in rivers are groundwater and tile flow. P was also released by surface runoff during large storm events when sediment was eroded into the rivers. The contributions of point sources in terms of waste water treatment plants to the overall P loading were low. The modifications made in the SWAT source code should be considered as a starting point to simulate P loads in artificially drained landscapes more precisely. Further testing and development of the code is required.

Highway deicing salt dynamic runoff to surface water and subsequent infiltration to groundwater during severe UK winters.

PubMed

Rivett, Michael O; Cuthbert, Mark O; Gamble, Richard; Connon, Lucy E; Pearson, Andrew; Shepley, Martin G; Davis, John

2016-09-15

Dynamic impact to the water environment of deicing salt application at a major highway (motorway) interchange in the UK is quantitatively evaluated for two recent severe UK winters. The contaminant transport pathway studied allowed controls on dynamic highway runoff and storm-sewer discharge to a receiving stream and its subsequent leakage to an underlying sandstone aquifer, including possible contribution to long-term chloride increases in supply wells, to be evaluated. Logged stream electrical-conductivity (EC) to estimate chloride concentrations, stream flow, climate and motorway salt application data were used to assess salt fate. Stream loading was responsive to salt applications and climate variability influencing salt release. Chloride (via EC) was predicted to exceed the stream Environmental Quality Standard (250mg/l) for 33% and 18% of the two winters. Maximum stream concentrations (3500mg/l, 15% sea water salinity) were ascribed to salt-induced melting and drainage of highway snowfall without dilution from, still frozen, catchment water. Salt persistance on the highway under dry-cold conditions was inferred from stream observations of delayed salt removal. Streambed and stream-loss data demonstrated chloride infiltration could occur to the underlying aquifer with mild and severe winter stream leakage estimated to account for 21 to 54% respectively of the 70t of increased chloride (over baseline) annually abstracted by supply wells. Deicing salt infiltration lateral to the highway alongside other urban/natural sources were inferred to contribute the shortfall. Challenges in quantifying chloride mass/fluxes (flow gauge accuracy at high flows, salt loading from other roads, weaker chloride-EC correlation at low concentrations), may be largely overcome by modest investment in enhanced data acquisition or minor approach modification. The increased understanding of deicing salt dynamic loading to the water environment obtained is relevant to improved groundwater resource management, highway salt application practice, surface-water - ecosystem management, and decision making on highway drainage to ground. Copyright © 2016 Elsevier B.V. All rights reserved.

A seesaw in Mediterranean precipitation during the Roman Period linked to millennial-scale changes in the North Atlantic

NASA Astrophysics Data System (ADS)

Dermody, B. J.; de Boer, H. J.; Bierkens, M. F. P.; Weber, S. L.; Wassen, M. J.; Dekker, S. C.

2012-03-01

We present a reconstruction of the change in climatic humidity around the Mediterranean between 3000-1000 yr BP. Using a range of proxy archives and model simulations we demonstrate that climate during this period was typified by a millennial-scale seesaw in climatic humidity between Spain and Israel on one side and the Central Mediterranean and Turkey on the other, similar to precipitation anomalies associated with the East Atlantic/West Russia pattern in current climate. We find that changes in the position and intensity of the jet stream indicated by our analysis correlate with millennial changes in North Atlantic sea surface temperature. A model simulation indicates the proxies of climatic humidity used in our analysis were unlikely to be influenced by climatic aridification caused by deforestation during the Roman Period. That finding is supported by an analysis of the distribution of archaeological sites in the Eastern Mediterranean which exhibits no evidence that human habitation distribution changed since ancient times as a result of climatic aridification. Therefore we conclude that changes in climatic humidity over the Mediterranean during the Roman Period were primarily caused by a modification of the jet stream linked to sea surface temperature change in the North Atlantic. Based on our findings, we propose that ocean-atmosphere coupling may have contributed to regulating Atlantic Meridional Overturning Circulation intensity during the period of analysis.

High Lapse Rates in AIRS Retrieved Temperatures in Cold Air Outbreaks

NASA Technical Reports Server (NTRS)

Fetzer, Eric J.; Kahn, Brian; Olsen, Edward T.; Fishbein, Evan

2004-01-01

The Atmospheric Infrared Sounder (AIRS) experiment, on NASA's Aqua spacecraft, uses a combination of infrared and microwave observations to retrieve cloud and surface properties, plus temperature and water vapor profiles comparable to radiosondes throughout the troposphere, for cloud cover up to 70%. The high spectral resolution of AIRS provides sensitivity to important information about the near-surface atmosphere and underlying surface. A preliminary analysis of AIRS temperature retrievals taken during January 2003 reveals extensive areas of superadiabatic lapse rates in the lowest kilometer of the atmosphere. These areas are found predominantly east of North America over the Gulf Stream, and, off East Asia over the Kuroshio Current. Accompanying the high lapse rates are low air temperatures, large sea-air temperature differences, and low relative humidities. Imagery from a Visible / Near Infrared instrument on the AIRS experiment shows accompanying clouds. These lines of evidence all point to shallow convection in the bottom layer of a cold air mass overlying warm water, with overturning driven by heat flow from ocean to atmosphere. An examination of operational radiosondes at six coastal stations in Japan shows AIRS to be oversensitive to lower tropospheric lapse rates due to systematically warm near-surface air temperatures. The bias in near-surface air temperature is seen to be independent of sea surface temperature, however. AIRS is therefore sensitive to air-sea temperature difference, but with a warm atmospheric bias. A regression fit to radiosondes is used to correct AIRS near-surface retrieved temperatures, and thereby obtain an estimate of the true atmosphere-ocean thermal contrast in five subtropical regions across the north Pacific. Moving eastward, we show a systematic shift in this air-sea temperature differences toward more isothermal conditions. These results, while preliminary, have implications for our understanding of heat flow from ocean to atmosphere. We anticipate future improvements in the AIRS retrieval algorithm will lead to improved understanding of the exchange of sensible and latent heat from ocean to atmosphere, and more realistic near-surface lapse rates.

Technical Report Series on Global Modeling and Data Assimilation. Volume 20; The Climate of the FVCCM-3 Model

NASA Technical Reports Server (NTRS)

Suarez, Max J. (Editor); Chang, Yehui; Schubert, Siegfried D.; Lin, Shian-Jiann; Nebuda, Sharon; Shen, Bo-Wen

2001-01-01

This document describes the climate of version 1 of the NASA-NCAR model developed at the Data Assimilation Office (DAO). The model consists of a new finite-volume dynamical core and an implementation of the NCAR climate community model (CCM-3) physical parameterizations. The version of the model examined here was integrated at a resolution of 2 degrees latitude by 2.5 degrees longitude and 32 levels. The results are based on assimilation that was forced with observed sea surface temperature and sea ice for the period 1979-1995, and are compared with NCEP/NCAR reanalyses and various other observational data sets. The results include an assessment of seasonal means, subseasonal transients including the Madden Julian Oscillation, and interannual variability. The quantities include zonal and meridional winds, temperature, specific humidity, geopotential height, stream function, velocity potential, precipitation, sea level pressure, and cloud radiative forcing.

Biological effect of low-head sea lamprey barriers: Designs for extensive surveys and the value of incorporating intensive process-oriented research

USGS Publications Warehouse

Hayes, D.B.; Baylis, J.R.; Carl, L.M.; Dodd, H.R.; Goldstein, J.D.; McLaughlin, R.L.; Noakes, D.L.G.; Porto, L.M.

2003-01-01

Four sampling designs for quantifying the effect of low-head sea lamprey (Petromyzon marinus) barriers on fish communities were evaluated, and the contribution of process-oriented research to the overall confidence of results obtained was discussed. The designs include: (1) sample barrier streams post-construction; (2) sample barrier and reference streams post-construction; (3) sample barrier streams pre- and post-construction; and (4) sample barrier and reference streams pre- and post-construction. In the statistical literature, the principal basis for comparison of sampling designs is generally the precision achieved by each design. In addition to precision, designs should be compared based on the interpretability of results and on the scale to which the results apply. Using data collected in a broad survey of streams with and without sea lamprey barriers, some of the tradeoffs that occur among precision, scale, and interpretability are illustrated. Although circumstances such as funding and availability of pre-construction data may limit which design can be implemented, a pre/post-construction design including barrier and reference streams provides the most meaningful information for use in barrier management decisions. Where it is not feasible to obtain pre-construction data, a design including reference streams is important to maintain the interpretability of results. Regardless of the design used, process-oriented research provides a framework for interpreting results obtained in broad surveys. As such, information from both extensive surveys and intensive process-oriented research provides the best basis for fishery management actions, and gives researchers and managers the most confidence in the conclusions reached regarding the effects of sea lamprey barriers.

Seasonal dynamics of surface chlorophyll concentration and sea surface temperature, as indicator of hydrological structure of the ocean (by satellite data)

NASA Astrophysics Data System (ADS)

Shevyrnogov, Anatoly; Vysotskaya, Galina

Continuous monitoring of phytopigment concentrations and sea surface temperature in the ocean by space-borne methods makes possible to estimate ecological condition of biocenoses in critical areas. Unlike land vegetation, hydrological processes largely determine phytoplank-ton dynamics, which may be either recurrent or random. The types of chlorophyll concentration dynamics and sea surface temperature can manifest as zones quasistationary by seasonal dynamics, quasistationary areas (QSA). In the papers of the authors (A. Shevyrnogov, G. Vysotskaya, E. Shevyrnogov, A study of the stationary and the anomalous in the ocean surface chlorophyll distribution by satellite data. International Journal of Remote Sensing, Vol. 25, No.7-8, pp. 1383-1387, April 2004 & A. P. Shevyrnogov, G. S. Vysotskaya, J. I. Gitelson, Quasistationary areas of chlorophyll concentra-tion in the world ocean as observed satellite data Advances in Space Research, Volume 18, Issue 7, Pages 129-132, 1996) existence of zones, which are quasi-stationary with similar seasonal dynamics of chlorophyll concentration at surface layer of ocean, was shown. Results were obtained on the base of processing of time series of satellite images SeaWiFS. It was shown that fronts and frontal zones coincide with dividing lines between quasi-stationary are-as, especially in areas of large oceanic streams. To study the dynamics of the ocean for the period from 1985 through 2012 we used data on the temperature of the surface layer of the ocean and chlorophyll concentration (AVHRR, SeaWiFS and MODIS). Biota of surface oceanic layer is more stable in comparison with quickly changing surface tem-perature. It gives a possibility to circumvent influence of high-frequency component (for exam-ple, a diurnal cycle) in investigation of dynamics of spatial distribution of surface streams. In addition, an analyses of nonstable ocean productivity phenomena, stood out time series of satellite images, showed existence of areas with different types of instability in the all Global ocean. They are observed as adjacent nonstationary zones of different size, which are associ-ated by different ways with known oceanic phenomena. It is evident that dynamics of a spatial distribution of biological productivity can give an additional knowledge of complicated picture of surface oceanic layer hydrology. In this study we demonstrate different origin of appearance of quasistationary zones in the ocean. We can see that the border between quasi¬stationary zones is an indicator of the front between the Labrador Current and Gulfstream, other example of revealed pheno¬menon is a qua-sistationary area around of the British Isles that correlates with the relief of the oceanic bottom. Considering that the QSA maps are calculated almost for all surface of the Global ocean, not all QSA can be explained especially of small size. Although some small QSA are interesting. Also local QSA near estuaries of large rivers and large industrial centers, that can be result of a human impact. In sum satellite data is a powerful instrument for investigation of dynamic oceanic processes, their stability and unstability. The result of such study can be used for monitoring of long-term changes and their correlation of with climate dynamics.

A qualitative appraisal of the hydrology of the Yemen Arab Republic from Landsat images

USGS Publications Warehouse

Grolier, Maurice J.; Tibbitts, G. Chase; Ibrahim, M.M.

1981-01-01

Six series of Landsat-1 and Landsat-2 images taken between 1972 and 1976 were analyzed to describe the flow regimens of streams and the regional distribution of vegetation in the Yemen Arab Republic. The findings provide a factual basis for planning a surface-water data collection program, and for preparing maps of plant distribution and agricultural land use. They lay the foundation for modernized water development, for effecting a program of country-wide water management. The work was undertaken as part of the program of the U.S. Agency for International Development with the cooperation of the Yemen Mineral and Petroleum Authority, Ministry of Economy. A false-color composite mosaic of the nine images which cover the country was prepared using Landsat 1 images taken at relatively low sun-angle in winter 1972-73. Catchment areas and the major drainage basins of the country were delineated on this mosaic. In order of increasing water availability, the four catchment areas of the YAR are: Ar Rub al Khali, Wadi Jawf (Arabian Sea), Red Sea, and Gulf of Aden. Most streams are ephemeral. No lakes were detected during the period under investigation, but sebkhas--salt flats or low salt-encrusted plains--are common along the Red Sea coast. In spite of resolution and scale constraints, streamflow was interpreted as perennial or intermittent, wherever it could be detected on several Landsat images covering the same scene at seasonal or yearly intervals. Much of the land under cultivation is restricted to valley floors, and to valley slopes and irrigated terraces adjacent to stream channels. Little or no vegetation could be detected over large regions of the Yemen Arab Republic. (USGS)

Balance of the West Antarctic Ice Sheet

NASA Technical Reports Server (NTRS)

2002-01-01

For several decades, measurements of the West Antarctic Ice Sheet showed it to be retreating rapidly. But new data derived from satellite-borne radar sensors show the ice sheet to be growing. Changing Antarctic ice sheets remains an area of high scientific interest, particularly in light of recent global warming concerns. These new findings are significant because scientists estimate that sea level would rise 5-6 meters (16-20 feet) if the ice sheet collapsed into the sea. Do these new measurements signal the end of the ice sheet's 10,000-year retreat? Or, are these new satellite data simply much more accurate than the sparse ice core and surface measurements that produced the previous estimates? Another possibility is that the ice accumulation may simply indicate that the ice sheet naturally expands and retreats in regular cycles. Cryologists will grapple with these questions, and many others, as they examine the new data. The image above depicts the region of West Antarctica where scientists measured ice speed. The fast-moving central ice streams are shown in red. Slower tributaries feeding the ice streams are shown in blue. Green areas depict slow-moving, stable areas. Thick black lines depict the areas that collect snowfall to feed their respective ice streams. Reference: Ian Joughin and Slawek Tulaczyk Science Jan 18 2002: 476-480. Image courtesy RADARSAT Antarctic Mapping Project

Management strategy evaluation of pheromone-baited trapping techniques to improve management of invasive sea lamprey

USGS Publications Warehouse

Dawson, Heather; Jones, Michael L.; Irwin, Brian J.; Johnson, Nicholas; Wagner, Michael C.; Szymanski, Melissa

2016-01-01

We applied a management strategy evaluation (MSE) model to examine the potential cost-effectiveness of using pheromone-baited trapping along with conventional lampricide treatment to manage invasive sea lamprey. Four pheromone-baited trapping strategies were modeled: (1) stream activation wherein pheromone was applied to existing traps to achieve 10−12 mol/L in-stream concentration, (2) stream activation plus two additional traps downstream with pheromone applied at 2.5 mg/hr (reverse-intercept approach), (3) trap activation wherein pheromone was applied at 10 mg/hr to existing traps, and (4) trap activation and reverse-intercept approach. Each new strategy was applied, with remaining funds applied to conventional lampricide control. Simulating deployment of these hybrid strategies on fourteen Lake Michigan streams resulted in increases of 17 and 11% (strategies 1 and 2) and decreases of 4 and 7% (strategies 3 and 4) of the lakewide mean abundance of adult sea lamprey relative to status quo. MSE revealed performance targets for trap efficacy to guide additional research because results indicate that combining lampricides and high efficacy trapping technologies can reduce sea lamprey abundance on average without increasing control costs.

Olfactory-mediated stream-finding behavior of migratory adult sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Vrieze, L.A.; Bergstedt, R.A.; Sorensen, P.W.

2011-01-01

Stream-finding behavior of adult sea lamprey (Petromyzon marinus), an anadromous fish that relies on pheromones to locate spawning streams, was documented in the vicinity of an important spawning river in the Great Lakes. Untreated and anosmic migrating sea lampreys were implanted with acoustic transmitters and then released outside the Ocqueoc River. Lampreys swam only at night and then actively. When outside of the river plume, lampreys pursued relatively straight bearings parallel to the shoreline while making frequent vertical excursions. In contrast, when within the plume, lampreys made large turns and exhibited a weak bias towards the river mouth, which one-third of them entered. The behavior of anosmic lampreys resembled that of untreated lampreys outside of the plume, except they pursued a more northerly compass bearing. To locate streams, sea lampreys appear to employ a three-phase odor-mediated strategy that involves an initial search along shorelines while casting vertically, followed by river-water-induced turning that brings them close to the river's mouth, which they then enter using rheotaxis. This novel strategy differs from that of salmonids and appears to offer this poor swimmer adaptive flexibility and suggests ways that pheromonal odors might be used to manage this invasive species.

Sea lamprey carcasses exert local and variable food web effects in a nutrient-limited Atlantic coastal stream

USGS Publications Warehouse

Weaver, Daniel M.; Coghlan, Stephen M.; Zydlewski, Joseph D.

2016-01-01

Resource flows from adjacent ecosystems are critical in maintaining structure and function of freshwater food webs. Migrating sea lamprey (Petromyzon marinus) deliver a pulsed marine-derived nutrient subsidy to rivers in spring when the metabolic demand of producers and consumers are increasing. However, the spatial and temporal dynamics of these nutrient subsidies are not well characterized. We used sea lamprey carcass additions in a small stream to examine changes in nutrients, primary productivity, and nutrient assimilation among consumers. Algal biomass increased 57%–71% immediately adjacent to carcasses; however, broader spatial changes from multiple-site carcass addition may have been influenced by canopy cover. We detected assimilation of nutrients (via δ13C and δ15N) among several macroinvertebrate families including Heptageniidae, Hydropsychidae, and Perlidae. Our research suggests that subsidies may evoke localized patch-scale effects on food webs, and the pathways of assimilation in streams are likely coupled to adjacent terrestrial systems. This research underscores the importance of connectivity in streams, which may influence sea lamprey spawning and elicit varying food web responses from carcass subsidies due to fine-scale habitat variables.

Anoxic groundwaters as a source of CO2 and PO4 for the coastal southern Baltic Sea: The role of an iron curtain

NASA Astrophysics Data System (ADS)

Lipka, Marko; Schneider, Jonas; Schmiedinger, Iris; Westphal, Julia; Escher, Peter; Sültenfuß, Jürgen; Dellwig, Olaf; Winde, Vera; Böttcher, Michael E.

2017-04-01

Submarine ground water discharge (SGD) into coastal ecosystems is perceived as an important source of fresh water and solutes (nutrients, metabolites, trace elements) in marine biogeochemical cycles. Less is known about its significance for the German coastal zone. We present here the results of hydrogeochemical and stable isotope geochemical studies in an area that is affected by SGD into the southern Baltic Sea. Anoxic groundwaters emerging as springs at the shore zone of the southern Baltic Sea are windows into the composition of subterrestrial ground water composition. They were investigated on a seasonal base for about five years. Water samples were analyzed for the concentrations of major and trace elements, pH, and the stable isotope ratios of water, DIC and sulfate. Newly formed precipitates in the stream bed were characterized via SEM-EDX and the stable isotope composition, as well as chemically extracted for the determination of the solid composition. The springs emerge in small pits yielding discharges of about 10 l/min each. Surrounding sediments are sandy with gravels found at depth and corresponding high permeabilities. The positions of different springs on the shore zone were geostationary during the investigation period while their shape varied due to wind- and wave action. The 2H and 18O contents of the spring waters indicate the ground water to originate from relatively young mixed meteoric waters. Dating by means of tritium and noble gases (3H, 3He, 4He, Ne) yields an age of the spring waters of about 25-32 years, with different mixing proportions of tritium-free waters. The springs are hydrogeochemically characterized by dissolved Ca, Mg, Na, bicarbonate, and sulfate, mainly reflecting the water-rock interaction with aquifer material in the recharge area. The isotope signature of DIC indicates the uptake of biogenic CO2 in the soil zone followed by the dissolution of carbonate minerals in the soil/ aquifer system. The oxygen-free ground water is rich in dissolved iron (Fe) and phosphorous (P). Iron(oxyhydr)oxide precipitates in the stream beds acting as a sink for dissolved PO4 and minor Ca. The investigation reveals that the surface precipitation on the beach leads to the formation of submarine groundwater discharge essentially free of dissolved Fe and PO4. The formation of Fe-phases in the subterranean estuary is supposed at depth influencing the release of nutrients and metals into the coastal ecosystem. Before the water passes to underground drainage into a subterranean mixing zone with brackish Baltic Sea waters, the above ground draining streams degas carbon dioxide and take up oxygen in contact with the atmosphere. Iron(oxyhydr)oxide precipitates in the stream beds acting as a sink for dissolved phosphate. Residues of Fe- oxidizing bacteria were found in the stream bed rust indicating an involvement of microbes to catalyze the dissolved Fe removal. The investigation reveals that the surface precipitation on the beach leads to the formation of submarine groundwater discharge essentially free of dissolved iron and phosphate. The formation of Fe-phases in the subterranean estuary is also supposed to take place at depth thereby influencing the release of nutrients and metals into the Baltic Sea coastal ecosystem. This work was supported by the BONUS+ project AMBER, the Leibniz IOW and the Graduiertenkolleg BALTIC TRANSCOAST.

Assimilation of Satellite Sea Surface Salinity Fields: Validating Ocean Analyses and Identifying Errors in Surface Buoyancy Fluxes

NASA Astrophysics Data System (ADS)

Mehra, A.; Nadiga, S.; Bayler, E. J.; Behringer, D.

2014-12-01

Recently available satellite sea-surface salinity (SSS) fields provide an important new global data stream for assimilation into ocean forecast systems. In this study, we present results from assimilating satellite SSS fields from NASA's Aquarius mission into the National Oceanic and Atmospheric Administration's (NOAA) operational Modular Ocean Model version 4 (MOM4), the oceanic component of NOAA's operational seasonal-interannual Climate Forecast System (CFS). Experiments on the sensitivity of the ocean's overall state to different relaxation time periods were run to evaluate the importance of assimilating high-frequency (daily to mesoscale) and low-frequency (seasonal) SSS variability. Aquarius SSS data (Aquarius Data Processing System (ADPS) version 3.0), mapped daily fields at 1-degree spatial resolution, were used. Four model simulations were started from the same initial ocean condition and forced with NOAA's daily Climate Forecast System Reanalysis (CFSR) fluxes, using a relaxation technique to assimilate daily satellite sea surface temperature (SST) fields and selected SSS fields, where, except as noted, a 30-day relaxation period is used. The simulations are: (1) WOAMC, the reference case and similar to the operational setup, assimilating monthly climatological SSS from the 2009 NOAA World Ocean Atlas; (2) AQ_D, assimilating daily Aquarius SSS; (3) AQ_M, assimilating monthly Aquarius SSS; and (4) AQ_D10, assimilating daily Aquarius SSS, but using a 10-day relaxation period. The analysis focuses on the tropical Pacific Ocean, where the salinity dynamics are intense and dominated by El Niño interannual variability in the cold tongue region and by high-frequency precipitation events in the western Pacific warm pool region. To assess the robustness of results and conclusions, we also examine the results for the tropical Atlantic and Indian Oceans. Preliminary validation studies are conducted using observations, such as satellite sea-surface height (SSH) fields and in situ Argo buoy vertical profiles of temperature and salinity, to demonstrate that SSS data assimilation improves ocean state representation of the following variables: ocean heat content (0-300m), dynamic height (0-1000m), mixed-layer depth, sea surface heigh, and surface buoyancy fluxes.

Distribution of fishes in U. S. streams tributary to Lake Superior

USGS Publications Warehouse

Moore, Harry H.; Braem, Robert A.

1965-01-01

Experimental sea lamprey control by the Bureau of Commercial Fisheries on Lake Superior streams provided many new distributional records of the fish fauna. Seventy-one species were recorded from 175 streams. Specimens were collected at the electromechanical barriers, with electric shockers, with fyke nets, and during chemical treatment of streams. Maps showing stream records of each species are presented.

Physical oceanography of the US Atlantic and eastern Gulf of Mexico. Final report

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

Milliman, J.D.; Imamura, E.

The report provides a summary of the physical oceanography of the U.S. Atlantic and Eastern Gulf of Mexico and its implication to offshore oil and gas exploration and development. Topics covered in the report include: meteorology and air-sea interactions, circulation on the continental shelf, continental slope and rise circulation, Gulf Stream, Loop Current, deep-western boundary current, surface gravity-wave climatology, offshore engineering implications, implications for resource commercialization, and numerical models of pollutant dispersion.

Seasonal sea ice predictions for the Arctic based on assimilation of remotely sensed observations

NASA Astrophysics Data System (ADS)

Kauker, F.; Kaminski, T.; Ricker, R.; Toudal-Pedersen, L.; Dybkjaer, G.; Melsheimer, C.; Eastwood, S.; Sumata, H.; Karcher, M.; Gerdes, R.

2015-10-01

The recent thinning and shrinking of the Arctic sea ice cover has increased the interest in seasonal sea ice forecasts. Typical tools for such forecasts are numerical models of the coupled ocean sea ice system such as the North Atlantic/Arctic Ocean Sea Ice Model (NAOSIM). The model uses as input the initial state of the system and the atmospheric boundary condition over the forecasting period. This study investigates the potential of remotely sensed ice thickness observations in constraining the initial model state. For this purpose it employs a variational assimilation system around NAOSIM and the Alfred Wegener Institute's CryoSat-2 ice thickness product in conjunction with the University of Bremen's snow depth product and the OSI SAF ice concentration and sea surface temperature products. We investigate the skill of predictions of the summer ice conditions starting in March for three different years. Straightforward assimilation of the above combination of data streams results in slight improvements over some regions (especially in the Beaufort Sea) but degrades the over-all fit to independent observations. A considerable enhancement of forecast skill is demonstrated for a bias correction scheme for the CryoSat-2 ice thickness product that uses a spatially varying scaling factor.

Thinning of the ice sheet in northwest Greenland over the past forty years.

PubMed

Paterson, W S; Reeh, N

2001-11-01

Thermal expansion of the oceans, as well as melting of glaciers, ice sheets and ice caps have been the main contributors to global sea level rise over the past century. The greatest uncertainty in predicting future sea level changes lies with our estimates of the mass balance of the ice sheets in Greenland and Antarctica. Satellite measurements have been used to determine changes in these ice sheets on short timescales, demonstrating that surface-elevation changes on timescales of decades or less result mainly from variations in snow accumulation. Here we present direct measurements of the changes in surface elevation between 1954 and 1995 on a traverse across the north Greenland ice sheet. Measurements over a time interval of this length should reflect changes in ice flow-the important quantity for predicting changes in sea level-relatively unperturbed by short-term fluctuations in snow accumulation. We find only small changes in the eastern part of the transect, except for some thickening of the north ice stream. On the west side, however, the thinning rates of the ice sheet are significantly higher and thinning extends to higher elevations than had been anticipated from previous studies.

Variability, trends, and teleconnections of stream flows with large-scale climate signals in the Omo-Ghibe River Basin, Ethiopia.

PubMed

Degefu, Mekonnen Adnew; Bewket, Woldeamlak

2017-04-01

This study assesses variability, trends, and teleconnections of stream flow with large-scale climate signals (global sea surface temperatures (SSTs)) for the Omo-Ghibe River Basin of Ethiopia. Fourteen hydrological indices of variability and extremes were defined from daily stream flow data series and analyzed for two common periods, which are 1972-2006 for 5 stations and 1982-2006 for 15 stations. The Mann-Kendall's test was used to detect trends at 0.05 significance level, and simple correlation analysis was applied to evaluate associations between the selected stream flow indices and SSTs. We found weak and mixed (upward and downward) trend signals for annual and wet (Kiremt) season flows. Indices generated for high-flow (flood) magnitudes showed the same weak trend signals. However, trend tests for flood frequencies and low-flow magnitudes showed little evidences of increasing change. It was also found that El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are the major anomalies affecting stream flow variability in the Omo-Ghibe Basin. The strongest associations are observed between ENSO/Niño3.4 and the stream flow in August and September, mean Kiremt flow (July-September), and flood frequency (peak over threshold on average three peaks per year (POT3_Fre)). The findings of this study provide a general overview on the long-term stream flow variability and predictability of stream flows for the Omo-Ghibe River Basin.

SeaWiFS Technical Report Series. Volume 38; SeaWiFS Calibration and Validation Quality Control Procedures

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); McClain, Charles R.; Darzi, Michael; Barnes, Robert A.; Eplee, Robert E.; Firestone, James K.; Patt, Frederick S.; Robinson, Wayne D.; Schieber, Brian D.;

Influence of ENSO on Gulf Stream cyclogenesis and the North Atlantic storm track

NASA Astrophysics Data System (ADS)

Li, C.; Schemm, S.; Ciasto, L.; Kvamsto, N. G.

2015-12-01

There is emerging evidence that climate in the North Atlantic-European sector is sensitive to vacillations of tropical Pacific sea surface temperatures, in particular, the central Pacific flavour of the El Nino Southern Oscillation (ENSO) and concomitant trends in atmospheric heating. The frequency of central Pacific ENSOs appears to have increased over the last decades and some studies suggest it may continue increasing in the future, but the precise mechanisms by which these events affect the North Atlantic synoptic scale circulation are poorly understood. Here, we show that central Pacific ENSOs influence where midlatitude cyclogenesis occurs over the Gulf Stream, producing more cyclogenesis in the jet exit region rather than in the climatologically preferred jet entrance region. The cyclones forming over the Gulf Stream in central Pacific ENSO seasons tend to veer north, penetrating deeper into the Arctic rather than into continental Europe. The shift in cyclogenesis is linked to changes in the large scale circulation, namely, the upper-level trough formed in the lee of the Rocky Mountains.

FROM THE MOUNTAINS TO THE SEA: THE STATE OF MARYLAND'S FRESHWATER STREAMS

EPA Science Inventory

The Maryland Biological Stream Survey, conducted by the Maryland Department of Natural Resources, sampled about 1,000 randomly-selected sites on first through third order freshwater streams throughout Maryland from 1995 to 1997. Biota (fish, benthic macroinvertebrates, herpetofau...

Passive Microwave Measurements of Salinity: The Gulf Stream Experiment

NASA Technical Reports Server (NTRS)

LeVine, D. M.; Koblinsky, C.; Haken, M.; Howden, S.; Bingham, F.; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (I psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approximately 0.2 psu) required of global maps to be scientifically viable. The development of a satellite microwave instrument to make global measurements of SSS (Sea Surface Salinity) is the focus of a joint JPL/GSFC/NASA ocean research program called Aquarius. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of airborne microwave instruments together with ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer (for surface temperature). These instruments were mounted on the NASA P-3 Orion aircraft. Sea surface measurements consisted of thermosalinograph data provided by the R/V Cape Henlopen and the MN Oleander, and data from salinity and temperature sensors on three surface drifters deployed from the R/V Cape Henlopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made with the airborne sensors on August 28 and 29 and on September 2 flights were made over the surface drifters to look for effects due to a change in surface roughness resulting from the passage of Hurricane Dennis. Results show a good agreement between the microwave measurements and ship measurements of salinity. The features of the brightness temperature maps correspond well with the features of the salinity field measured by the ship and drifters and a preliminary retrieval of salinity compares well with the ship data.

Palaeo-ice stream pathways in the easternmost Amundsen Sea Embayment, West Antarctica

NASA Astrophysics Data System (ADS)

Klages, Johann P.; Kuhn, Gerhard; Graham, Alastair G. C.; Smith, James A.; Hillenbrand, Claus-Dieter; Nitsche, Frank O.; Larter, Rob D.; Gohl, Karsten

2015-04-01

Multibeam swath bathymetry datasets collected over the past two decades have been compiled to identify palaeo-ice stream pathways in the easternmost Amundsen Sea Embayment. We mapped 3010 glacial landforms to reconstruct palaeo-ice flow in the ~250 km-long Abbot Glacial Trough that was occupied by a large palaeo-ice stream, fed by two tributaries (Cosgrove and Abbot) that reached the continental shelf edge during the last maximum ice-sheet advance. The mapping has enabled a clear differentiation between glacial landforms interpreted as indicative of wet- (e.g. mega-scale glacial lineations) and cold-based ice (e.g. hill-hole pairs) during the last glaciation of the continental shelf. Both the regions of fast palaeo-ice flow within the palaeo-ice stream troughs, and the regions of slow palaeo-ice flow on adjacent seafloor highs (referred to as inter-ice stream ridges) additionally record glacial landforms such as grounding-zone wedges and recessional moraines that indicate grounding line stillstands of the ice sheet during the last deglaciation from the shelf. As the palaeo-ice stream flowed along a trough with variable geometry and variable subglacial substrate, it appears that trough sections characterized by constrictions and outcropping hard substrate that changes the bed gradient, led the pace of grounding-line retreat to slow and subsequently pause, resulting in the deposition of grounding-zone wedges. The stepped retreat recorded within the Abbot Glacial Trough corresponds well to post-glacial stepped retreat interpreted for the neighbouring Pine Island-Thwaites Palaeo-Ice Stream trough, thus suggesting a uniform pattern of episodic retreat across the eastern Amundsen Sea Embayment. The correlation of episodic retreat features with geological boundaries further emphasises the significance of subglacial geology in steering ice stream flow. Our new geomorphological map of the easternmost Amundsen Sea Embayment resolves the pathways of palaeo-ice streams that were probably all active during the last maximum extent of the ice sheet on this part of the shelf, and reveals the style of postglacial grounding-line retreat. Both are important input variables in ice sheet models and therefore can be used for validating the reliability of these models.

The role of sea surface circulation and hydrographic processes in anchovy spawning and larvae distribution in the Strait of Sicily (Central Mediterranean).

NASA Astrophysics Data System (ADS)

Falcini, Federico; Palatella, Luigi; Cuttitta, Angela; Bignami, Francesco; Patti, Bernardo; Santoleri, Rosalia; Fiorentino, Fabio

2014-05-01

The European Anchovy (Engraulis encrasicolus, Linnaeus, 1758) is one of the most important resources of the Mediterranean Sea. Despite its abundance and relevance, the anchovy population off the Mediterranean coasts exhibits a patchy distribution. Moreover, its biology and the influence of environment on its variability is poorly known. We here use data from ichthyoplankton-surveys carried out during the peak spawning season in order to analyze abundance and age of anchovy larvae in the Strait of Sicily, with respect to sea surface dynamic and hydrographic parameter patterns. The Strait of Sicily dynamics is characterized by upwelling regions, fronts, vortices, and filaments, with a consequent complexity in the spatial distribution of oceanographic parameters and anchovy larvae. To investigate the role of mesoscale features and oceanographic environment on the latter, anchovy larvae observations were paired to remote sensing data (such as sea surface temperature, chlorophyll, primary production, surface wind speed as well as light attenuation, absorption, and particle backscattering coefficients) and Lagrangian and Eulerian numerical simulations results for ocean currents and larval transport. The subsequent analysis shows and quantifies how the Atlantic Ionian Stream (AIS, a meandering current of Atlantic origin) path and variability, as well as the upwelling-induced south Sicilian coastal current, have consequences for anchovy spawning and larvae distribution. These currents transport anchovy larvae towards the Sicilian coast's south-eastern tip, where larvae are then retained in a frontal structure. However, significant cross-shore transport events due to relatively cold filament-like baroclinic instabilities generated by wind-induced coastal upwelling were also observed. Finally, the larval age distribution qualitatively agrees well with this transport pattern.

Simulating LGM retreat of the Uummannaq Ice Stream and Rinks Isbrae, Western Greenland using a 1-D ice-stream model constrained by a suite of marine and terrestrial data

NASA Astrophysics Data System (ADS)

Jamieson, Stewart; Roberts, Dave; Rea, Brice; Lane, Timothy; Vieli, Andreas; Cofaigh, Colm Ó.

2014-05-01

We aim to understand what controlled the retreat pattern of the Uummannaq Ice Stream (UIS) during the last deglaciation. Evidence for the pattern of retreat is found in both the marine and terrestrial realms, but because the evidence is temporally and spatially discontinuous, it is challenging to coherently reconstruct both grounding-line retreat and ice-surface thinning such that they are in agreement. Marine stratigraphic and geophysical evidence indicates that the ice stream was grounded close to the continental shelf edge at the Last Glacial Maximum, and retreated rapidly and nonlinearly after 14.8 ka. Cosmogenic nuclide exposure dating on Ubekendt Island at the convergence zone of multiple feeder ice streams show that the ice surface thinned progressively and that the island became ice-free by ca. 12.4 ka. The ice stream then collapsed over the next 1-1.6 kyrs and the ice stream separated into a series of distinct inland arms. In the northernmost Rinks system, there is a 'staircase' of evidence showing ice surface thinning over time, but it is unclear where the grounding line was located during this phase of thinning. Furthermore, it is currently unclear what controlled the nonlinear retreat pattern identified in the Uummannaq system. We develop a numerical model of ice-stream retreat using the marine geophysical data and measurements of sediment strength on the continental shelf to control the boundary conditions. The model has the capability to dynamically and robustly simulate grounding line-retreat behaviour over millennial timescales. We simulate the retreat of the UIS grounding line into the northernmost Rinks system in response to enhanced ocean warming, rising sea level and warming climate. We compare the simulated dynamic behaviour of the UIS against the geomorphological and cosmogenic exposure evidence for ice surface thinning onshore and against dated marine grounding line positions. Our model results enable us to match grounding-line positions in the marine trough to distinct onshore ice-surface heights, and therefore provide a 2-dimensional reconstruction of the geometry of the UIS as it retreated after the LGM. We find that the nonlinearity in retreat rate is conditioned by the locations of vertical and lateral constrictions in the Uummannaq/Rink trough which provide temporary pinning points for the grounding line. When the grounding line retreats rapidly between pinning points, the ice surface thins rapidly inland. When the grounding line is pinned, thinning of the ice surface becomes much slower in locations corresponding to the deposition of moraines. We suggest that the slowdowns in retreat identified in the marine domain are therefore reflected by the generation of moraines in the terrestrial domain. Finally, we generate hypotheses about the timing of marine grounding-line retreat based upon the published terrestrial cosmogenic exposure ages.

Ice in Channels and Ice-Rock Mixtures in Valleys on Mars: Did They Slide on Deformable Rubble Like Antarctic Ice Streams?

NASA Technical Reports Server (NTRS)

Lucchitta, B. K.

1997-01-01

Recent studies of ice streams in Antarctica reveal a mechanism of basal motion that may apply to channels and valleys on Mars. The mechanism is sliding of the ice on deformable water-saturated till under high pore pressures. It has been suggested by Lucchitta that ice was present in outflow channels on Mars and gave them their distinctive morphology. This ice may have slid like Antarctic ice streams but on rubbly weathering products rather than till. However, to generate water under high pore pressures, elevated heatflow is needed to melt the base of the ice. Either volcanism or higher heatflow more than 2 b.y. ago could have raised the basal temperature. Regarding valley networks, higher heatflow 3 b.y. ago could have allowed sliding of ice-saturated overburden at a few hundred meters depth. If the original, pristine valleys were somewhat deeper than they are now, they could have formed by the same mechanism. Recent sounding of the seafloor in front of the Ross Ice Shelf in Antarctica reveals large persistent patterns of longitudinal megaflutes and drumlinoid forms, which bear remarkable resemblance to longitudinal grooves and highly elongated streamlined islands found on the floors of martian outflow channels. The flutes are interpreted to have formed at the base of ice streams during the last glacial advance. Additional similarities of Antarctic ice streams with martian outflow channels are apparent. Antarctic ice streams are 30 to 80 km wide and hundreds of kilometers long. Martian outflow channels have similar dimensions. Ice stream beds are below sea level. Carr determined that most common floor elevations of martian outflow channels lie below martian datum, which may have been close to or below past martian sea levels. The Antarctic ice stream bed gradient is flat and locally may go uphill, and surface slopes are exceptionally. Martian channels also have floor gradients that are shallow or go uphill locally and have low surface gradients. The depth to the bed in ice streams is 1 to 1.5 km. At bankful stage, the depth of the fluid in outflow channels was 1 to 2 km, according to the height of bordering scarps. The similarity between Antarctic ice streams and martian outflow channels suggests that ice may have flowed through and shaped the outflow channels, and that perhaps the mechanism of motion of Antarctic ice streams also operated in outflow channels. In addition, sliding on deformable rubble may explain the formation of small valley networks. The large Siple Coast Antarctic ice streams are thought to slide over longitudinally grooved, deforming till, where much of the movement is within the till. The till is saturated with water at high pore pressures that nearly supports all of the weight of the ice. The small differential between overburden pressure and pore pressure at the bed is more important than the volume of water, but water needs to be supplied to the till interface. For pore pressures to remain high, the ice streams have to act as a seal that blocks the flow of water through them, and the rock underneath has to be of low permeability to prevent the water from draining away.

Entrainment and mixing of shelf/slope waters in the near-surface Gulf Stream

NASA Astrophysics Data System (ADS)

Lillibridge, J. L., III; Hitchcock, G.; Rossby, T.; Lessard, E.; Mork, M.; Golmen, L.

1990-08-01

An interdisciplinary study of the entrainment of shelf and slope waters in the Gulf Stream front was undertaken in October 1985 northeast of Cape Hatteras. Fifteen hydrographic transects of the Gulf Stream front and of the shelf water intrusion known as Ford water were completed in 2 1/2 days with a towed undulating profiler, the SeaSoar, equipped with a conductivity-temperature-depth probe and a fluorometer. Upstream sections within 50 km of the shelf break show entrainment of surface and subsurface waters along the northern edge of the high-velocity Gulf Stream. The low-salinity core, first observed at 70 m, is subducted to >100 m. The subsurface Ford water is also at a maximum in chlorophyll, fluorescence, and dissolved oxygen and contains a distinct diatom assemblage of nearshore species. Productivity rates in the Ford water may be equivalent to those in slope waters. Expendable current profilers yield an estimated transport for subsurface shelf waters of 1 to 5×105 m3 s-1 and indicate that vertical shear at the depth of maximum static stability is typically 2×10-2 s-1. A bulk Richardson number is estimated over vertical scales of several meters by combining SeaSoar density profiles with velocity shear from concurrent expendable current profiler deployments. The minimum values are generally >1, and only infrequently are they at or below the 0.25 threshold for shear instability. The presence of double-diffusive processes around the low-salinity core of Ford water is indicated by elevated conductivity Cox numbers. The stability parameter "Turner angle" shows that low-salinity Ford water and its associated T-S property front are sites of double-diffusive mixing, given general agreement between the distributions of Turner angle and Cox number. We conclude that double-diffusive processes are more important than shear flow instability in governing cross-isopycnal mixing. However, downstream transit times are so swift that no measurable change or decay occurs in the Ford water. This explains the occurrence of distinct shelf water phytoplankton species within the low-salinity waters downstream of Cape Hatteras.

Physical Processes Involved in the 1988 Drought and 1993 Floods in North America.

NASA Astrophysics Data System (ADS)

Trenberth, Kevin E.; Guillemot, Christian J.

1996-06-01

An analysis of the spring-summer 1988 drought and 1993 floods over North America reveals a reversal in the sign of anomalies in several fields. Large sea surface temperature anomalies of opposite signs existed in the tropical Pacific with strong La Niña conditions in 1988 and a mature El Niño in 1993. The distribution of tropical convection in the convergence zones and associated latent heating of the atmosphere were correspondingly altered, implying a large-scale switch in the anomalous tropical heating and forcing of extratropical quasi-stationary waves in the atmosphere, influencing the subtropical jet stream over the North Pacific and across North America. In 1988 the jet stream and the closely related storm track of high-frequency disturbances in the upper troposphere were displaced into Canada well north of the normal location-the farthest north of any year from 1979 to 1993. In 1993 a broader jet stream and the storm track were displaced well south of normal to a more springlike location across the United States-the farthest south by over 200 km of any year from 1979 to 1993. High-frequency eddy activity in the Pacific-North American storm track is shown to reinforce the anomalous jet streams in both years.An analysis of the moisture budgets reveals a stronger river of atmospheric moisture flowing across the Gulf of Mexico into the central and eastern United States in 1993. Also, in the lower atmosphere, the storm track in 1993 was more active, and its lower latitude allowed the cyclonic disturbances to tap into the moisture source, transport moisture into the upper Mississippi River basin, and precipitate it out. It is deduced that local evaporation may have enhanced the precipitation and helped perpetuate and prolong the conditions. In contrast, in 1988 disturbances were weaker and displaced far enough north to avoid most of the moisture source, and the drought was perpetuated by the dry conditions. Consequently, these effects should be viewed as feedbacks that amplify and prolong the response, while from the standpoint of the atmosphere, the anomalous tropical Pacific sea surface temperatures are a notable (but not the sole) external forcing of the patterns.

Ice stream behaviour in the western sector of the North Sea during the end of the last glacial cycle

NASA Astrophysics Data System (ADS)

Roberts, David; Evans, David; Clark, Chris; Bateman, Mark; Livingstone, Stephen; Medialdea, Alicia; Cofaigh, Colm O.; Grimoldi, Elena; Callard, Louise; Dove, Dayton; Stewart, Heather; Davies, Bethan; Chiverell, Richard

2016-04-01

During the last glacial cycle the East coast of the UK was overrun by the British-Irish Ice Sheet (BIIS) flowing eastwards and southwards. In recent years it has become evident that several ice streams including the Tweed, Tyne, and Stainmore Gap ice streams, as well as the late stage North Sea Lobe (NSL), all played a role in shaping the glacial landscape during this period, but understanding the flow phasing of these ice streams during advance and collapse has proved challenging. Here we present new data from the seafloor collected during recent work undertaken by the Britice Chrono and Glanam project teams during cruise JC123 in the North Sea. Sub-bottom seafloor data together with new swath data clearly show that the final phases of the collapse of the NSL were controlled by ice sourced from the Firth of Forth ice stream which deglaciated in a NNW trajectory. Other ice streams being fed from the west (e.g. Stainmore, Tyne, Tweed) were not influential in final phase ice retreat from the southern North Sea. The Forth ice imprint is characterised by several grounding zone/till wedges marking dynamic, oscillatory retreat of the ice as it retreated along an offshore corridor between North Yorkshire and Northumberland. Repeated packages of tills, ice marginal and glaciomarine sediments, which drape glacially scoured bedrock terrain and drumlins along this corridor, point to marine inundation accompanying ice retreat. New TCN ages suggest decoupling of the Tyne Gap ice stream and NSL between 17.8 and 16.5 ka and this coincides with rapid, regional collapse of the NSL between 17.2 and 16.0 ka along the Yorkshire and Durham coasts (new OSL ages; Britice Chrono). Hence, both the central and northern sectors of the BIIS were being strongly influenced by marine margin instability during the latter phases of the last glacial cycle.

Antarctic ice shelf potentially stabilized by export of meltwater in surface river.

PubMed

Bell, Robin E; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J; Zappa, Christopher J; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

2017-04-19

Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks-interconnected streams, ponds and rivers-on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf's meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica-contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

Antarctic Ice Shelf Potentially Stabilized by Export of Meltwater in Surface River

NASA Technical Reports Server (NTRS)

Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

2017-01-01

Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks-interconnected streams, ponds and rivers-on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf's meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica-contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

Antarctic ice shelf potentially stabilized by export of meltwater in surface river

NASA Astrophysics Data System (ADS)

Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

2017-04-01

Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

Arctic Amplification and the Northward shift of a new Greenland melting record

NASA Astrophysics Data System (ADS)

Tedesco, Marco; Mote, Thomas; Fettweis, Xavier; Hanna, Edward; Booth, James; Jeyaratnam, Jeyavinoth; Datta, Rajashree; Briggs, Kate

2016-04-01

Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Using reanalysis data and the outputs of a regional climate model, here we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean was responsible for a northward shift of surface melting records over Greenland, and for increased accumulation in the south during the summer of 2015. Concurrently, new records of mean monthly zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5700±50 m isohypse over the Arctic were also set. An unprecedented (1948 - 2015) and sustained jet stream easterly flow promoted enhanced runoff, increased surface temperatures and decreased albedo in northern Greenland, while inhibiting melting in the south. The exceptional 2015 summer Arctic atmospheric conditions are consistent with the anticipated effects of Arctic Amplification, including slower zonal winds and increased jet stream wave amplitude. Properly addressing the impact of Arctic Amplification on surface runoff of the Greenland ice sheet is crucial for rigorously quantifying its contribution to current and future sea level rise, and the relative impact of freshwater discharge on the surrounding ocean.

Spatially-resolved mean flow and turbulence help explain observed erosion and deposition patterns of snow over Antarctic sea ice

NASA Astrophysics Data System (ADS)

Trujillo, E.; Giometto, M. G.; Leonard, K. C.; Maksym, T. L.; Meneveau, C. V.; Parlange, M. B.; Lehning, M.

2014-12-01

Sea ice-atmosphere interactions are major drivers of patterns of sea ice drift and deformations in the Polar regions, and affect snow erosion and deposition at the surface. Here, we combine analyses of sea ice surface topography at very high-resolutions (1-10 cm), and Large Eddy Simulations (LES) to study surface drag and snow erosion and deposition patterns from process scales to floe scales (1 cm - 100 m). The snow/ice elevations were obtained using a Terrestrial Laser Scanner during the SIPEX II (Sea Ice Physics and Ecosystem eXperiment II) research voyage to East Antarctica (September-November 2012). LES are performed on a regular domain adopting a mixed pseudo-spectral/finite difference spatial discretization. A scale-dependent dynamic subgrid-scale model based on Lagrangian time averaging is adopted to determine the eddy-viscosity in the bulk of the flow. Effects of larger-scale features of the surface on wind flows (those features that can be resolved in the LES) are accounted for through an immersed boundary method. Conversely, drag forces caused by subgrid-scale features of the surface should be accounted for through a parameterization. However, the effective aerodynamic roughness parameter z0 for snow/ice is not known. Hence, a novel dynamic approach is utilized, in which z0 is determined using the constraint that the total momentum flux (drag) must be independent on grid-filter scale. We focus on three ice floe surfaces. The first of these surfaces (October 6, 2012) is used to test the performance of the model, validate the algorithm, and study the spatial distributed fields of resolved and modeled stress components. The following two surfaces, scanned at the same location before and after a snow storm event (October 20/23, 2012), are used to propose an application to study how spatially resolved mean flow and turbulence relates to observed patterns of snow erosion and deposition. We show how erosion and deposition patterns are correlated with the computed stresses, with modeled stresses having higher explanatory power. Deposition is mainly occurring in wake regions of specific ridges that strongly affect wind flow patterns. These larger ridges also lock in place elongated streaks of relatively high speeds with axes along the stream-wise direction, and which are largely responsible for the observed erosion.

Tectonic and lithological controls on fluvial landscape development in central-eastern Portugal: Insights from long profile tributary stream analyses

NASA Astrophysics Data System (ADS)

Martins, António A.; Cabral, João; Cunha, Pedro P.; Stokes, Martin; Borges, José; Caldeira, Bento; Martins, A. Cardoso

2017-01-01

This study examines the long profiles of tributaries of the Tagus and Zêzere rivers in Portugal (West Iberia) in order to provide new insights into patterns, timing, and controls on drainage development during the Quaternary incision stage. The studied streams are incised into a relict culminant fluvial surface, abandoned at the beginning of the incision stage. The streams flow through a landscape with bedrock variations in lithology (mainly granites and metasediments) and faulted blocks with distinct uplift rates. The long profiles of the analyzed streams record an older transitory knickpoint/knickzone separating (1) an upstream relict graded profile, with lower steepness and higher concavity, that reflects a long period of quasi-equilibrium conditions reached after the beginning of the incision stage, and (2) a downstream rejuvenated long profile, with steeper gradient and lower concavity, particularly for the final reach, which is often convex. The rejuvenated reaches testify to the upstream propagation of several incision waves, interpreted as the response of each stream to increasing crustal uplift and prolonged periods of base-level lowering by the trunk drainages, coeval with low sea level conditions. The morphological configurations of the long profiles enabled spatial and relative temporal patterns of incisions to be quantified. The incision values of streams flowing on the Portuguese Central Range (PCR; ca. 380-150 m) are variable but generally higher than the incision values of streams flowing on the adjacent South Portugal Planation Surface (SPPS; ca. 220-110 m), corroborating differential uplift of the PCR relative to the SPPS. Owing to the fact that the relict graded profiles can be correlated with the Tagus River T1 terrace (1.1-0.9 My) present in the study area, incision rates can be estimated (1) for the streams located in the PCR, 0.38-0.15 m/ky and (2) for the streams flowing on the SPPS, 0.22-0.12 m/ky. The differential uplift inferred in the study area supports the neotectonic activity of the bordering faults, as proposed in previous studies based upon other geological evidence.

Determining the Pollution Parameters of Degirmendere Stream (Trabzon, NE TURKEY)

NASA Astrophysics Data System (ADS)

Sunnetci, M. O.; Hatipoglu, E.; Firat Ersoy, A.; Gultekin, F.

2013-12-01

The pollution parameters of Degirmendere Stream (Trabzon, TURKEY) are determined in this study. The study area is located between Maçka, 26 km to the south of Trabzon city, and the Black Sea. The area consists of Late Cretaceous volcano-sedimentary rocks, dacite, and basalt, overlain by Eocene volcanic rocks. Quaternary alluvium overlay all geological units following Degirmendere Stream bed. In-situ physical parameter measurements, anion-cation analysis, and heavy and pollutant element analysis on water samples were carried out for four months at four different locations on the stream. The stream's water temperature values were between 4.7 and 9.7oC, pH values were between 6.01 and 7.98, dissolved oxygen (DO) values were between 7.03 and 12.38 mg/l, electrical conductivity (EC) values were between 86 and 254 μS/cm. According to the Piper diagram, the stream water is classified as Ca-HCO3 type water. In the Schoeller diagram, the lines combining mek/l values of the ions in stream water are parallel. Al concentration in the stream water varied from 0.06 to 0.22 mg/l, Mn concentration varied from 0.1 to 0.36 mg/l, and Fe concentration varied from 0.01 to 0.12 mg/l. The stream water is classified as first class in point of temperature, pH, DO, total dissolved solids (TDS), NO3-, P, Pb, Fe, and Al; first and second class in point of NH4+; second class in point of Cu; and third class in point of NO2-, according to the Water Pollution Control Regulation of the Turkish Republic's Criteria for Inland Surface Water Classification. Results indicate waters of the Degirmendere Stream is very good-good for irrigation use according to the Wilcox diagram.

Linking landscape characteristics and stream nitrogen in the Oregon Coast Range: Empirical modeling of water quality monitoring data

EPA Science Inventory

Background sources of nitrogen (N) provide a challenge for setting stream nutrient criteria in the Pacific Northwest US. Red alder (Alnus rubra), an early successional nitrogen fixing tree, and sea salt inputs can strongly influence stream N concentrations observed in individual...

Investigation of environmental change pattern in Japan. Investigation of variations in the prominent oceanic current, Kuroshio

NASA Technical Reports Server (NTRS)

Maruyasu, T.; Shoji, D. (Principal Investigator)

1976-01-01

The author has identified the following significant results. From ocean current analysis, it is concluded that the vortex was formed when the stream axis of the Kuroshio was gradually approaching Shiono Misaki. The sea surface temperatures in the area were found to be nearly homogenious having the values of 27.3 to 27.8C. Transparency of the water was better on the east side of Shiono Misaki than on the west side, the values being 20 to 27 m against 13m. Surface salinity distribution had a considerably high value of 33.7% on the east side, decreasing toward the west to become 32%.

Decadal-scale sensitivity of Northeast Greenland ice flow to errors in surface mass balance using ISSM

NASA Astrophysics Data System (ADS)

Schlegel, N.-J.; Larour, E.; Seroussi, H.; Morlighem, M.; Box, J. E.

2013-06-01

The behavior of the Greenland Ice Sheet, which is considered a major contributor to sea level changes, is best understood on century and longer time scales. However, on decadal time scales, its response is less predictable due to the difficulty of modeling surface climate, as well as incomplete understanding of the dynamic processes responsible for ice flow. Therefore, it is imperative to understand how modeling advancements, such as increased spatial resolution or more comprehensive ice flow equations, might improve projections of ice sheet response to climatic trends. Here we examine how a finely resolved climate forcing influences a high-resolution ice stream model that considers longitudinal stresses. We simulate ice flow using a two-dimensional Shelfy-Stream Approximation implemented within the Ice Sheet System Model (ISSM) and use uncertainty quantification tools embedded within the model to calculate the sensitivity of ice flow within the Northeast Greenland Ice Stream to errors in surface mass balance (SMB) forcing. Our results suggest that the model tends to smooth ice velocities even when forced with extreme errors in SMB. Indeed, errors propagate linearly through the model, resulting in discharge uncertainty of 16% or 1.9 Gt/yr. We find that mass flux is most sensitive to local errors but is also affected by errors hundreds of kilometers away; thus, an accurate SMB map of the entire basin is critical for realistic simulation. Furthermore, sensitivity analyses indicate that SMB forcing needs to be provided at a resolution of at least 40 km.

Ku-band ocean radar backscatter observations during SWADE

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, F. K.; Lou, S. H.; Neumann, G.

1993-01-01

We present results obtained by an airborne Ku-band scatterometer during the Surface Wave Dynamics Experiment (SWADE). The specific objective of this study is to improve our understanding of the relationship between ocean radar backscatter and near surface winds. The airborne scatterometer, NUSCAT, was flown on the NASA Ames C-130 over an instrumented oceanic area near 37 deg N and 74 deg W. A total of 10 flights from 27 Feb. to 9 Mar. 1991 were conducted. Radar backscatter at incidence angles of 0 to 60 deg were obtained. For each incidence angle, the NUSCAT antenna was azimuthally scanned in multiple complete circles to measure the azimuthal backscatter modulations. Both horizontal and vertical polarization backscatter measurements were made. In some of the flights, the cross-polarization backscatter was measured as well. Internal calibrations were carried out throughout each of the flights. Preliminary results indicate that the radar was stable to +/-0.3 dB for each flight. In this paper, we present studies of the backscatter measurements over several crossings of the Gulf Stream. In these crossings, large air-sea temperature differences were encountered and substantial changes in the radar cross section were observed. We summarize the observations and compare them to the changes of several wind variables across the Gulf Stream boundary. In one of the flights, the apparent wind near the cold side of the Gulf Stream was very low (less than 3 m/s). The behavior of the radar cross sections at such low wind speeds and a comparison with models are presented. A case study of the effects of swell on the absolute cross section and the azimuthal modulation pattern is presented. Significant wave heights larger than m were observed during SWADE. The experimentally observed effects of the swell on the radar backscatter are discussed. The effects are used to assess the uncertainties in wind retrieval due to underlying waves. A summary of azimuthal modulation from our ten-flight of NUSCAT data is given. Wind velocities, air and sea surface temperature, ocean spectrum, and other variables measured from aircraft and buoys are also shown.

The interaction of prehistoric human settlement, sea level change and tectonic uplift of the Coastal Range, eastern Taiwan

NASA Astrophysics Data System (ADS)

Yang, H.; Chen, W. S.

2017-12-01

The late Cenozoic mountain belt of Taiwan, resulting from the collision between the Eurasian and Philippine Sea plates, is known for its rapid tectonic uplift. As postglacial sea level rose ca. 15,000 yr ago, the eastern coast of Taiwan, due to the rapid tectonic uplift rate, displayed a totally different scenario comparing with most of the coastal plains around the world. At the beginning of postglacial era, the sea level rising rate was greater than the tectonic uplift rate which induced the original piedmont alluvial fan or coastal plain to be overwhelmed by sea water rapidly. Around 13.5 ka, the tectonic uplift rate caught up with the sea level rising and broad wave-cut platform formed. The approximation of tectonic uplift and sea level rising rates was lasting from 13.5 to 5ka, but shoreline progradation may have been enhanced by increased slope erosion which resulted in the alluvial fan forming at the later time of this period. As soon as the eustasy stabilized, the landmass continued to uplift which might have enhanced the river incising and wave erosion rapidly. Therefore the topographic expression along the eastern fringing of Coastal Range forms extended alluvial-fan, stream, and marine terraces and are covered by late Holocene colluvium and marine deposits. 88 archaeological sites were chosen in this study based on surface survey where the archaeological chronology of cultural stage is established primarily through examining pottery series and associated manual excavation. It is interesting that most of the archaeological sites were located on the alluvial fan although the Holocene marine terraces have formed after 5ka. There are no clear evidences to support a shore-oriented settlement, but the abundant alluvial depositional structures observed from the overlaying formation reveals the stream depositional system was still active at this time. If the Neolithic people wanted to come to the "new born" coastal region for the abundant ocean resources, they have to face the flat marine terraces should be still situated in inter-tidal or shallow sub-tidal zone and the alluvial fan where river began to incise might be a better choice for habitation.

High-precision GPS autonomous platforms for sea ice dynamics and physical oceanography

NASA Astrophysics Data System (ADS)

Elosegui, P.; Wilkinson, J.; Olsson, M.; Rodwell, S.; James, A.; Hagan, B.; Hwang, B.; Forsberg, R.; Gerdes, R.; Johannessen, J.; Wadhams, P.; Nettles, M.; Padman, L.

2012-12-01

Project "Arctic Ocean sea ice and ocean circulation using satellite methods" (SATICE), is the first high-rate, high-precision, continuous GPS positioning experiment on sea ice in the Arctic Ocean. The SATICE systems collect continuous, dual-frequency carrier-phase GPS data while drifting on sea ice. Additional geophysical measurements also collected include ocean water pressure, ocean surface salinity, atmospheric pressure, snow-depth, air-ice-ocean temperature profiles, photographic imagery, and others, enabling sea ice drift, freeboard, weather, ice mass balance, and sea-level height determination. Relatively large volumes of data from each buoy are streamed over a satellite link to a central computer on the Internet in near real time, where they are processed to estimate the time-varying buoy positions. SATICE system obtains continuous GPS data at sub-minute intervals with a positioning precision of a few centimetres in all three dimensions. Although monitoring of sea ice motions goes back to the early days of satellite observations, these autonomous platforms bring out a level of spatio-temporal detail that has never been seen before, especially in the vertical axis. These high-resolution data allows us to address new polar science questions and challenge our present understanding of both sea ice dynamics and Arctic oceanography. We will describe the technology behind this new autonomous platform, which could also be adapted to other applications that require high resolution positioning information with sustained operations and observations in the polar marine environment, and present results pertaining to sea ice dynamics and physical oceanography.

Deglaciation of the Western Margin of the Barents Sea Ice Sheet - a Swath Bathymetric and Sub-Bottom Seismic Study from Eglacom Nice-Streams Data in the Kveithola Trough

NASA Astrophysics Data System (ADS)

Rebesco, M.; Liu, Y.; Camerlenghi, A.; Winsborrow, M. C.; Laberg, J.; Caburlotto, A.; Diviacco, P.; Accettella, D.; Sauli, C.; Wardell, N.

2010-12-01

IPY Activity N. 367 focusing on Neogene ice streams and sedimentary processes on high- latitude continental margins (NICE-STREAMS) resulted in two coordinated cruises on the adjacent Storfjorden and Kveithola trough-mouth fans in the NW Barents Sea: SVAIS Cruise of BIO Hespérides, summer 2007, and EGLACOM Cruise of Cruise R/V OGS-Explora, summer 2008. The objectives were to acquire a high-resolution set of bathymetric, seismic and sediment core data in order to decipher the Neogene architectural development of the glacially-dominated NW Barents Sea continental margin in response to natural climate change. The paleo-ice streams drained ice from southern Spitsbergen, Spitsbergen Bank, and Bear Island. The short distance from the ice source to the calving front produced a short residence time of ice, and therefore a rapid response to climatic changes. We describe here the EGLACOM data collected within the Kveithola Trough, an E-W trending glacial trough in the NW Barents Sea, NW of the Bear Island. Swath bathymetry shows that the seafloor is characterised by E-W trending mega-scale glacial lineations (MSGL) that record a fast flowing ice stream draining the Svalbard/Barents Sea Ice Sheet (SBIS) during the Last Glacial Maximum (LGM). MSGL are overprinted by transverse sediment ridges about 15 km apart which give rise to a staircase axial profile of the trough. Such transverse ridges are interpreted as grounding-zone wedges (GZW) formed by deposition of unconsolidated, saturated subglacial till during episodic ice stream retreat. Sub-bottom (CHIRP) and multi-channel reflection seismic data show that present-day morphology is largely inherited from the palaeo-seafloor topography at the time of deposition of the transverse ridges, overlain by a draping glaciomarine unit up to over 15 m thick. Our data allow the reconstruction of depositional processes that accompanied the deglaciation of the Spitsbergen Bank area. The sedimentary drape deposited on top of the GZWs which accumulated at a very high rate in the order of 1-1.5 m ka-1 has a potential to preserve a high resolution palaeoclimatic record of the deglaciation and post-glacial condition in this sector of the Barents Sea.

TOPEX/El Nino Watch - Warm Water Pool is Thinning, Feb, 5, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Feb. 5, 1998 and sea surface height is an indicator of the heat content of the ocean. The area and volume of the El Nino warm water pool that is affecting global weather patterns remains extremely large, but the pool has thinned along the equator and near the coast of South America. This 'thinning' means that the warm water is not as deep as it was a few months ago. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition that they would expect to see during the ocean's gradual transition back to normal sea level. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

The last glaciation of Bear Peninsula, central Amundsen Sea Embayment of Antarctica: Constraints on timing and duration revealed by in situ cosmogenic 14C and 10Be dating

NASA Astrophysics Data System (ADS)

Johnson, Joanne S.; Smith, James A.; Schaefer, Joerg M.; Young, Nicolás E.; Goehring, Brent M.; Hillenbrand, Claus-Dieter; Lamp, Jennifer L.; Finkel, Robert C.; Gohl, Karsten

2017-12-01

Ice streams in the Pine Island-Thwaites region of West Antarctica currently dominate contributions to sea level rise from the Antarctic ice sheet. Predictions of future ice-mass loss from this area rely on physical models that are validated with geological constraints on past extent, thickness and timing of ice cover. However, terrestrial records of ice sheet history from the region remain sparse, resulting in significant model uncertainties. We report glacial-geological evidence for the duration and timing of the last glaciation of Hunt Bluff, in the central Amundsen Sea Embayment. A multi-nuclide approach was used, measuring cosmogenic 10Be and in situ14C in bedrock surfaces and a perched erratic cobble. Bedrock 10Be ages (118-144 ka) reflect multiple periods of exposure and ice-cover, not continuous exposure since the last interglacial as had previously been hypothesized. In situ14C dating suggests that the last glaciation of Hunt Bluff did not start until 21.1 ± 5.8 ka - probably during the Last Glacial Maximum - and finished by 9.6 ± 0.9 ka, at the same time as ice sheet retreat from the continental shelf was complete. Thickening of ice at Hunt Bluff most likely post-dated the maximum extent of grounded ice on the outer continental shelf. Flow re-organisation provides a possible explanation for this, with the date for onset of ice-cover at Hunt Bluff providing a minimum age for the timing of convergence of the Dotson and Getz tributaries to form a single palaeo-ice stream. This is the first time that timing of onset of ice cover has been constrained in the Amundsen Sea Embayment.

Technical Report Series on Global Modeling and Data Assimilation. Volume 22; A Coupled Ocean-Atmosphere Radiative Model for Global Ocean Biogeochemical Models

NASA Technical Reports Server (NTRS)

Gregg, Watson W.; Suarez, Max J. (Editor)

2002-01-01

An ocean-atmosphere radiative model (OARM) evaluates irradiance availability and quality in the water column to support phytoplankton growth and drive ocean thermodynamics. An atmospheric component incorporates spectral and directional effects of clear and cloudy skies as a function of atmospheric optical constituents, and spectral reflectance across the air-sea interface. An oceanic component evaluates the propagation of spectral and directional irradiance through the water column as a function of water, five phytoplankton groups, and chromophoric dissolved organic matter. It tracks the direct and diffuse streams from the atmospheric component, and a third stream, upwelling diffuse irradiance. The atmospheric component of OARM was compared to data sources at the ocean surface with a coefficient of determination (r2) of 0.97 and a root mean square of 12.1%.

Multiplatform sampling (ship, aircraft, and satellite) of a Gulf Stream warm core ring

NASA Technical Reports Server (NTRS)

Smith, Raymond C.; Brown, Otis B.; Hoge, Frank E.; Baker, Karen S.; Evans, Robert H.

1987-01-01

The purpose of this paper is to demonstrate the ability to meet the need to measure distributions of physical and biological properties of the ocean over large areas synoptically and over long time periods by means of remote sensing utilizing contemporaneous buoy, ship, aircraft, and satellite (i.e., multiplatform) sampling strategies. A mapping of sea surface temperature and chlorophyll fields in a Gulf Stream warm core ring using the multiplatform approach is described. Sampling capabilities of each sensing system are discussed as background for the data collected by means of these three dissimilar methods. Commensurate space/time sample sets from each sensing system are compared, and their relative accuracies in space and time are determined. The three-dimensional composite maps derived from the data set provide a synoptic perspective unobtainable from single platforms alone.

Low-head sea lamprey barrier effects on stream habitat and fish communities in the Great Lakes basin

USGS Publications Warehouse

Dodd, H.R.; Hayes, D.B.; Baylis, J.R.; Carl, L.M.; Goldstein, J.D.; McLaughlin, R.L.; Noakes, D.L.G.; Porto, L.M.; Jones, M.L.

2003-01-01

Low-head barriers are used to block adult sea lamprey (Petromyzon marinus) from upstream spawning habitat. However, these barriers may impact stream fish communities through restriction of fish movement and habitat alteration. During the summer of 1996, the fish community and habitat conditions in twenty-four stream pairs were sampled across the Great Lakes basin. Seven of these stream pairs were re-sampled in 1997. Each pair consisted of a barrier stream with a low-head barrier and a reference stream without a low-head barrier. On average, barrier streams were significantly deeper (df = 179, P = 0.0018) and wider (df = 179, P = 0.0236) than reference streams, but temperature and substrate were similar (df = 183, P = 0.9027; df = 179, P = 0.999). Barrier streams contained approximately four more fish species on average than reference streams. However, streams with low-head barriers showed a greater upstream decline in species richness compared to reference streams with a net loss of 2.4 species. Barrier streams also showed a peak in richness directly downstream of the barriers, indicating that these barriers block fish movement upstream. Using S??renson's similarity index (based on presence/absence), a comparison of fish community assemblages above and below low-head barriers was not significantly different than upstream and downstream sites on reference streams (n = 96, P > 0.05), implying they have relatively little effect on overall fish assemblage composition. Differences in the frequency of occurrence and abundance between barrier and reference streams was apparent for some species, suggesting their sensitivity to barriers.

Evidence for lack of homing by sea lampreys

USGS Publications Warehouse

Bergstedt, Roger A.; Seelye, James G.

1995-01-01

Recently metamorphosed sea lampreys Petromyzon marinus were captured in the Devil River, a tributary to Lake Huron, during summer and autumn 1990. They were tagged with a coded wire tag and returned to the river to continue their migration to Lake Huron to begin the parasitic (juvenile) phase of their life. During the spawning run in spring 1992 when the tagged animals were expected to mature and return to spawn, sea lampreys were trapped in nine tributaries to Lake Huron, including the Devil River; 47,946 animals were examined for coded wire tags, and 41 tagged animals were recovered. None of the 45 mature sea lampreys captured in the Devil River in 1992 were tagged, a proportion (0%) significantly lower than the proportion of the recently metamorphosed sea lampreys tagged in 1990. The distribution of tag recoveries among streams lakewide, however, was proportional to catch. Tagged sea lampreys did not appear to home, but instead seemed to select spawning streams through innate attraction to other sensory cues.

Investigating the Greenland ice sheet evolution under changing climate using a three-dimensional full-Stokes model

NASA Astrophysics Data System (ADS)

Seddik, H.; Greve, R.; Zwinger, T.; Gillet-Chaulet, F.; Gagliardini, O.

2010-12-01

A three-dimensional, thermo-mechanically coupled model is applied to the Greenland ice sheet. The model implements the full-Stokes equations for the ice dynamics, and the system is solved with the finite-element method (FEM) using the open source multi-physics package Elmer (http://www.csc.fi/elmer/). The finite-element mesh for the computational domain has been created using the Greenland surface and bedrock DEM data with a spatial resolution of 5 km (SeaRise community effort, based on Bamber and others, 2001). The study is particularly aimed at better understanding the ice dynamics near the major Greenland ice streams. The meshing procedure starts with the bedrock footprint where a mesh with triangle elements and a resolution of 5 km is constructed. Since the resulting mesh is unnecessarily dense in areas with slow ice dynamics, an anisotropic mesh adaptation procedure has been introduced. Using the measured surface velocities to evaluate the Hessian matrix of the velocities, a metric tensor is computed at the mesh vertices in order to define the adaptation scheme. The resulting meshed footprint obtained with the automatic tool YAMS shows a high density of elements in the vicinities of the North-East Greenland Ice Stream (NEGIS), the Jakobshavn ice stream (JIS) and the Kangerdlugssuaq (KL) and Helheim (HH) glaciers. On the other hand, elements with a coarser resolution are generated away from the ice streams and domain margins. The final three-dimensional mesh is obtained by extruding the 2D footprint with 21 vertical layers, so that the resulting mesh contains 400860 wedge elements and 233583 nodes. The numerical solution of the Stokes and the heat transfer equations involves direct and iterative solvers depending on the simulation case, and both methods are coupled with stabilization procedures. The boundary conditions are such that the temperature at the surface uses the present-day mean annual air temperature given by a parameterization or directly from the available data, the geothermal heat flux at the bedrock is prescribed as spatially constant and the lateral sides are open boundaries. A non-linear Weertman law is used for the basal sliding. The project goal is to better assess the effects of dynamical changes of the Greenland ice sheet on sea level rise under global-warming conditions. Hence, the simulations have been conducted in order to investigate the ice sheet evolution using the climate forcing experiments defined in the SeaRISE project. For that purpose, four different experiments have been conducted, (i) constant climate control run beginning at present (epoch 2004-1-1 0:0:0) and running up to 500 years holding the climate constant to its present state, (ii) constant climate forcing with increased basal lubrication, (iii) AR4 climate run forced by anomalies derived from results given in the IPCC 4th Assessment Report (AR4) for the A1B emission scenario, (iv) AR4 climate run with increased basal lubrication.

An Annual Cycle Of Currents Around Tsushima Island And Resulting Inflow Conditions In The Sea Of Japan

NASA Astrophysics Data System (ADS)

Perkins, H.; Teague, W. J.; Chang, K.-I.; Suk, M.-S.; Lee, J.-C.; Book, J. W.; Jacobs, G. A.

A ten-month long time series of current measurements has been made on two sections across Korea/Tsushima Strait, thus revealing most of an annual cycle of the Tsushima Current that flows into the Japan/East Sea. One section is southwest, the other north- east, of Tsushima Island, giving respectively conditions upstream and downstream of the Island. Along the bathymetric slope upstream of the Island, the current consists of a single, broad stream concentrated in mid-channel. Downstream, this single core is found to have separated into two branches, one on each of the Strait. Between these two near-coastal streams, in the apparent wake of the Island, currents are variable and lack a well-defined mean. This separation persisted during all seasons despite vari- ation in total transport by a factor of two, from 3.5 Sv in October 1999 to 1.7 Sv in January 2000, and despite changes from maximum to minimum stratification. Both branches of the divided current were stronger during high transport and weaker during low transport, but since each branch was measured by only one or two moorings, trans- port estimates for the separate branches are not available. Strongest currents occurred at the surface close to the Korean coast near Ulsan in early fall with low-pass surface currents reaching 90 cm/s during October and November. Farther downstream, outside the measurement area, the two branches define the inflow to the Japan/East Sea. The branch along the Japanese coast remains close to the coast. It undergoes strong annual variability but is steady on shorter time scales. The Korean branch of the current also undergoes strong annual changes but experiences very strong variability, especially in winter. This branch is thought to switch between two paths. The first parallels the Ko- rean coast; the second follows bathymetric contours that lead it back to the Japanese coast. A mechanism for switching between these paths is provided by vorticity asso- ciated with bottom intrusions of cold water in the area. Seasonal variations of flow into the Japan Sea thus depend on the interplay between seasonal variations around Tsushima Island and intrusions of cold bottom water.

Improved age constraints for the retreat of the Irish Sea Ice Stream

NASA Astrophysics Data System (ADS)

Smedley, Rachel; Chiverrell, Richard; Duller, Geoff; Scourse, James; Small, David; Fabel, Derek; Burke, Matthew; Clarke, Chris; McCarroll, Danny; McCarron, Stephen; O'Cofaigh, Colm; Roberts, David

2016-04-01

BRITICE-CHRONO is a large (> 45 researchers) consortium project working to provide an extensive geochronological dataset constraining the rate of retreat of a number of ice streams of the British-Irish Ice Sheet following the Last Glacial Maximum. When complete, the large empirical dataset produced by BRITICE-CHRONO will be integrated into model simulations to better understand the behaviour of the British-Irish Ice Sheet in response to past climate change, and provide an analogue for contemporary ice sheets. A major feature of the British-Irish Ice Sheet was the dynamic Irish Sea Ice Stream, which drained a large proportion of the ice sheet and extended to the proposed southern limit of glaciation upon the Isles of Scilly (Scourse, 1991). This study will focus on a large suite of terrestrial samples that were collected along a transect of the Irish Sea basin, covering the line of ice retreat from the Isles of Scilly (50°N) in the south, to the Isle of Man (54°N) in the north; a distance of 500 km. Ages are determined for both the eastern and western margins of the Irish Sea using single-grain luminescence dating (39 samples) and terrestrial cosmogenic nuclide dating (10 samples). A Bayesian sequence model is then used in combination with the prior information determined for deglaciation to integrate the geochronological datasets, and assess retreat rates for the Irish Sea Ice Stream. Scourse, J.D., 1991. Late Pleistocene stratigraphy and palaeobotany of the Isles of Scilly. Philosophical Transactions of the Royal Society of London B334, 405 - 448.

Natural chlorine and fluorine in the atmosphere, water and precipitation

NASA Technical Reports Server (NTRS)

Friend, James P.

1990-01-01

The geochemical cycles of chlorine and fluorine are surveyed and summarized as framework for the understanding of the global natural abundances of these species in the atmosphere, water, and precipitation. In the cycles the fluxes into and out of the atmosphere can be balanced within the limits of our knowledge of the natural sources and sinks. Sea salt from the ocean surfaces represent the predominant portion of the source of chlorine. It is also an important source of atmospheric fluorine, but volcanoes are likely to be more important fluorine sources. Dry deposition of sea salt returns about 85 percent of the salt released there. Precipitation removes the remainder. Most of the sea salt materials are considered to be cyclic, moving through sea spray over the oceans and either directly back to the oceans or deposited dry and in precipitation on land, whence it runs off into rivers and streams and returns to the oceans. Most of the natural chlorine in the atmosphere is in the form of particulate chloride ion with lesser amounts as gaseous inorganic chloride and methyl chloride vapor. Fluorine is emitted from volcanoes primarily as HF. It is possible that HF may be released directly form the ocean surface but this has not been confirmed by observation. HCl and most likely HF gases are released into the atmosphere by sea salt aerosols. The mechanism for the release is likely to be the provision of protons from the so-called excess sulfate and HNO3. Sea salt aerosol contains fluorine as F(-), MgF(+), CaF(+), and NaF. The concentrations of the various species of chlorine and fluorine that characterize primarily natural, unpolluted atmospheres are summarized in tables and are discussed in relation to their fluxes through the geochemical cycle.

Decomposition of sea lamprey Petromyzon marinus carcasses: temperature effects, nutrient dynamics, and implications for stream food webs

USGS Publications Warehouse

Weaver, Daniel M.; Coghlan, Stephen M.; Zydlewski, Joseph D.; Hogg, Robert S.; Canton, Michael

2015-01-01

Anadromous fishes serve as vectors of marine-derived nutrients into freshwaters that are incorporated into aquatic and terrestrial food webs. Pacific salmonines Oncorhynchus spp. exemplify the importance of migratory fish as links between marine and freshwater systems; however, little attention has been given to sea lamprey (Petromyzon marinus Linnaeus, 1758) in Atlantic coastal systems. A first step to understanding the role of sea lamprey in freshwater food webs is to characterize the composition and rate of nutrient inputs. We conducted laboratory and field studies characterizing the elemental composition and the decay rates and subsequent water enriching effects of sea lamprey carcasses. Proximate tissue analysis demonstrated lamprey carcass nitrogen:phosphorus ratios of 20.2:1 (±1.18 SE). In the laboratory, carcass decay resulted in liberation of phosphorus within 1 week and nitrogen within 3 weeks. Nutrient liberation was accelerated at higher temperatures. In a natural stream, carcass decomposition resulted in an exponential decline in biomass, and after 24 days, the proportion of initial biomass remaining was 27% (±3.0% SE). We provide quantitative results as to the temporal dynamics of sea lamprey carcass decomposition and subsequent nutrient liberation. These nutrient subsidies may arrive at a critical time to maximize enrichment of stream food webs.

What is water?

USGS Publications Warehouse

,

1965-01-01

If a schoolboy asked this question, you would answer it easily enough. "Why, water is a liquid found in and around the earth. Water is the sea, lakes, streams, springs and what comes gushing out of the tap when we turn it on." If he still looks a little unsatisfied, you would explain that our bodies are three-fourths water, and that water covers threefourths of the earth's surface. But you would have to admit to yourself that these facts, interesting as they are, do not quite answer the boy's question: "What is water?"

On the dynamic forcing of short-term climate fluctuations by feedback mechanisms

NASA Technical Reports Server (NTRS)

Reiter, E. R.

1979-01-01

Various internal feedback mechanisms in the ocean atmosphere system were studied. A variability pattern of sea surface temperature with a quasibiennial oscillation (QBO) was detected off the coast of Senegal, in the Gulf of Guinea and even in the Gulf Stream as it leaves the North American continental shelf. Possible physical connections between some of these QBO's were pointed out by a hypothetical feedback model. Interaction of a QBO with the annual cycle may lead to beating frequencies resembling climatic trends of a duration of several years.

Impingement of water droplets on wedges and double-wedge airfoils at supersonic speeds

NASA Technical Reports Server (NTRS)

Serafini, John S

1954-01-01

An analytical solution has been obtained for the equations of motion of water droplets impinging on a wedge in a two-dimensional supersonic flow field with a shock wave attached to the wedge. The closed-form solution yields analytical expressions for the equation of the droplet trajectory, the local rate of impingement and the impingement velocity at any point on the wedge surface, and the total rate of impingement. The analytical expressions are utilized to determine the impingement on the forward surfaces of diamond airfoils in supersonic flow fields with attached shock waves. The results presented include the following conditions: droplet diameters from 2 to 100 microns, pressure altitudes from sea level to 30,000 feet, free-stream static temperatures from 420 degrees r, free stream Mach numbers from 1.1 to 2.0, semiapex angles for the wedge from 1.14 degrees to 7.97 degrees, thickness-to-chord ratios for the diamond airfoil from 0.02 to 0.14, chord lengths from 1 to 20 feet, and angles of attack from zero to the inverse tangent of the airfoil thickness-to-chord ratio.

Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

EPA Science Inventory

Red alder (a nitrogen-fixing tree) and sea salt inputs can strongly influence stream nitrogen concentrations in western Oregon and Washington. We compiled a database of stream nitrogen and landscape characteristics in the Oregon Coast Range. Basal area of alder, expressed as a ...

Spatial variation in basic chemistry of streams draining a volcanic landscape on Costa Rica's Caribbean slope

USGS Publications Warehouse

Pringle, C.M.; Triska, F.J.; Browder, G.

1990-01-01

Spatial variability in selected chemical, physical and biological parameters was examined in waters draining relatively pristine tropical forests spanning elevations from 35 to 2600 meters above sea level in a volcanic landscape on Costa Rica's Caribbean slope. Waters were sampled within three different vegetative life zones and two transition zones. Water temperatures ranged from 24-25 ??C in streams draining lower elevations (35-250 m) in tropical wet forest, to 10 ??C in a crater lake at 2600 m in montane forest. Ambient phosphorus levels (60-300 ??g SRP L-1; 66-405 ??g TP L-1) were high at sites within six pristine drainages at elevations between 35-350 m, while other undisturbed streams within and above this range in elevation were low (typically <30.0 ??g SRP L-1). High ambient phosphorus levels within a given stream were not diagnostic of riparian swamp forest. Phosphorus levels (but not nitrate) were highly correlated with conductivity, Cl, Na, Ca, Mg and SO4. Results indicate two major stream types: 1) phosphorus-poor streams characterized by low levels of dissolved solids reflecting local weathering processes; and 2) phosphorus-rich streams characterized by relatively high Cl, SO4, Na, Mg, Ca and other dissolved solids, reflecting dissolution of basaltic rock at distant sources and/or input of volcanic brines. Phosphorus-poor streams were located within the entire elevation range, while phosphorus-rich streams were predominately located at the terminus of Pleistocene lava flows at low elevations. Results indicate that deep groundwater inputs, rich in phosphorus and other dissolved solids, surface from basaltic aquifers at breaks in landform along faults and/or where the foothills of the central mountain range merge with the coastal plain. ?? 1990 Kluwer Academic Publishers.

Stratigraphic response of salt marshes to slow rates of sea-level change

NASA Astrophysics Data System (ADS)

Daly, J.; Bell, T.

2006-12-01

Conventional models of salt-marsh development show an idealized spatial relationship between salt-marsh floral and foraminiferal zones, where the landward margin of the marsh gradually migrates inland in response to sea-level rise. This model predicts that transgression will result in persistent and possibly expanded salt marshes at the surface, depending on a variety of factors including sediment supply, hydrologic conditions, tidal range, and rate of sea-level rise. However, in areas with abundant sediment supply and slow rates of sea- level rise, the extent of back-barrier salt marshes may decline over time as the barrier-spits mature. Sea level around the northeast coast of Newfoundland is rising at a very slow rate during the late Holocene (<0.5 mm/yr). Sandy barrier-spits and tombolos are common coastal features, but salt marshes are rare. The generalized stratigraphy of dutch cores collected in back-barrier settings in this region is a surface layer of sphagnum peat with abundant woody roots, underlain by sedge-dominated peat that transitions gradually to a thin layer of Juncus sp. peat with agglutinated foraminifera, dominantly Jadammina macrescens and Balticammina pseudomacrescens. These basal peats are interpreted as salt-marsh peats, characterized by the presence of foraminifera that are absent in overlying peat units. This sequence indicates that salt marshes developed in back-barrier environments during the initial stages of barrier progradation, then gradually transitioned to environments increasingly dominated by freshwater flora. These transitions are interpreted to reflect the progradation of the spit, decreased tidal exchange in the back-barrier, and increased influence of freshwater streams discharging into the back-barrier setting. Decreased marine influence on the back-barrier environment leads to a floral and faunal shift associated with a regressive stratigraphy in an area experiencing sea-level rise. For studies of Holocene sea-level change requiring salt-marsh stratigraphic records, it is necessary to account for changing micro-environments to locate sites appropriate for study; salt marshes may play an important role in defining the record, but may not exist at the surface to guide investigation.

Greek Wildfires

NASA Technical Reports Server (NTRS)

2002-01-01

Hot, dry weather has contributed to a string of fires that burned in Greece during the first two weeks of July 2000. Smoke from one of these fires is streaming across Greece and out into the Aegean Sea in this image taken July 13, 2000, by the Sea-viewing Wide Field of view Sensor (SeaWiFS). For more about SeaWiFS, visit the SeaWiFS home page. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

A Improved and Highly Effective Seabed Surface Sand Sampling Device

NASA Astrophysics Data System (ADS)

Liu, Ying

2017-04-01

In marine geology research, it is necessary to obtain a sufficient quantity of seabed surface samples, while also ensuring that the samples are in their original state. Currently, there are a number of seabed surface sampling devices available, but it is very difficult to obtain sand samples using ordinary seabed surface sampling devices, whereas machine-controlled seabed surface sampling devices are unable to dive into deeper regions of water. To obtain larger quantities of samples in their original states, many researchers have tried to improve seabed surface sampling devices, but these efforts have generally produced ambiguous results. To resolve the aforementioned issue, we have designed an improved and highly effective seabed surface sand sampling device, which incorporates the strengths of a variety of sampling devices; it is capable of diving into deeper water regions to obtain sand samples, and is also suited for use in streams, rivers, lakes and seas with varying levels of flow velocities and depth.

CEOS Ocean Variables Enabling Research and Applications for Geo (COVERAGE)

NASA Astrophysics Data System (ADS)

Tsontos, V. M.; Vazquez, J.; Zlotnicki, V.

2017-12-01

The CEOS Ocean Variables Enabling Research and Applications for GEO (COVERAGE) initiative seeks to facilitate joint utilization of different satellite data streams on ocean physics, better integrated with biological and in situ observations, including near real-time data streams in support of oceanographic and decision support applications for societal benefit. COVERAGE aligns with programmatic objectives of CEOS (the Committee on Earth Observation Satellites) and the missions of GEO-MBON (Marine Biodiversity Observation Network) and GEO-Blue Planet, which are to advance and exploit synergies among the many observational programs devoted to ocean and coastal waters. COVERAGE is conceived of as 3 year pilot project involving international collaboration. It focuses on implementing technologies, including cloud based solutions, to provide a data rich, web-based platform for integrated ocean data delivery and access: multi-parameter observations, easily discoverable and usable, organized by disciplines, available in near real-time, collocated to a common grid and including climatologies. These will be complemented by a set of value-added data services available via the COVERAGE portal including an advanced Web-based visualization interface, subsetting/extraction, data collocation/matchup and other relevant on demand processing capabilities. COVERAGE development will be organized around priority use cases and applications identified by GEO and agency partners. The initial phase will be to develop co-located 25km products from the four Ocean Virtual Constellations (VCs), Sea Surface Temperature, Sea Level, Ocean Color, and Sea Surface Winds. This aims to stimulate work among the ocean VCs while developing products and system functionality based on community recommendations. Such products as anomalies from a time mean, would build on the theme of applications with a relevance to CEOS/GEO mission and vision. Here we provide an overview of the COVERAGE initiative with an emphasis on international collaborative aspects entailed with the intent of soliciting community feedback as we develop and implement

The Impact of Sea Level Rise on Florida's Everglades

NASA Astrophysics Data System (ADS)

Senarath, S. U.

2005-12-01

Global warming and the resulting melting of polar ice sheets could increase global sea levels significantly. Some studies have predicted mean sea level increases in the order of six inches to one foot in the next 25 to 50 years. This could have severe irreversible impacts on low-lying areas of Florida's Everglades. The key objective of this study is to evaluate the effects of a one foot sea level rise on Cape Sable Seaside Sparrow (CSSS) nesting areas within the Everglades National Park (ENP). A regional-scale hydrologic model is used to assess the sensitivities of this sea-level rise scenario. Florida's Everglades supports a unique ecosystem. At present, about 50 percent of this unique ecosystem has been lost due to urbanization and farming. Today, the water flow in the remnant Everglades is also regulated to meet a variety of competing environmental, water-supply and flood-control needs. A 30-year, eight billion dollar (1999 estimate) project has been initiated to improve Everglades' water flows. The expected benefits of this restoration project will be short-lived if the predicted sea level rise causes severe impacts on the environmentally sensitive areas of the Everglades. Florida's Everglades is home to many threatened and endangered species of wildlife. The Cape Sable Seaside Sparrow population in the ENP is one such species that is currently listed as endangered. Since these birds build their nests close to the ground surface (the base of the nest is approximately six inches from the ground surface), they are directly affected by any sea level induced ponding depth, frequency or duration change. Therefore, the CSSS population serves as a good indicator species for evaluating the negative impacts of sea level rise on the Everglades' ecosystem. The impact of sea level rise on the CSSS habitat is evaluated using the Regional Simulation Model (RSM) developed by the South Florida Water Management District. The RSM is an implicit, finite-volume, continuous, distributed, and integrated surface-water and ground-water model. It can simulate one-dimensional canal/stream flow and two-dimensional overland and groundwater flow in arbitrarily shaped areas using a variable triangular mesh. The overland and groundwater flow components are fully coupled in the RSM for a more realistic representation of runoff generation.

IAS Mesoscale Surface Circulation Observed Through Satellite Altimetry and its Influence in a Small Scale, Coastal Domain, Studied with a ROMS Model of the Cariaco Basin.

NASA Astrophysics Data System (ADS)

Alvera-Azcarate, A.; Barth, A.; Virmani, J. I.; Weisberg, R. H.

2007-05-01

The Intra-Americas Sea (IAS) surface circulation is characterized by large scale currents. The Caribbean current, which originates in the Lesser Antilles, travels westwards through the Caribbean Sea and eastern Mexico and passes through the Gulf of Mexico to finally form the Gulf Stream. This complex system of currents is also characterized by a high mesoscale variability, such as eddies and meanders. The objectives of this work are twofold: first, the multi-scale surface circulation of the IAS is described using satellite altimetry. The topographic influence of the different basins forming the IAS, the characteristic time and spatial scales, and the time variability of the surface circulation will be addressed. The second objective is to analyze the influence of this large scale circulation on a small scale coastal domain with a ROMS-based model of the Cariaco basin (Venezuela). Cariaco is a deep (1400 m), semi-enclosed basin connected to the open ocean by two shallow channels (Tortuga and Centinela Channels). Its connection with the open sea, and therefore the ventilation of the basin, occurs in the surface layers. The Cariaco ROMS model will be used to study the exchanges of mass, heat and salt through the channels. A 1/60 degree ROMS model nested in the global 1/12 degree HYCOM model from the Naval Research Laboratory will be used for this study. In addition, a series of observations (satellite altimetry and in situ temperature, salinity and velocity data), will be used to assess the influence of the Caribbean circulation on the basin.

Using Sediment Provenance to Study Ice Streams in the Weddell Sea Embayment of Antarctica

NASA Astrophysics Data System (ADS)

Hemming, S. R.; Williams, T.; Boswell, S.; Licht, K.; Agrios, L.; Brachfeld, S. A.; van de Flierdt, T.; Kuhn, G.; Hillenbrand, C. D.; Zhai, X.

2016-12-01

The geochemical and geochronological fingerprint of rock debris eroded and carried by ice streams may be used to identify the provenance of iceberg-rafted debris (IRD) in the marine sediment record. During deglacial times it has been shown that there is an increase in IRD accumulation in marine sediments underlying the western limb of the Weddell Gyre. We seek to find the provenance of this IRD, identify the ice streams contributing to the IRD load, and interpret the geographic sequence of ice sheet retreat in the Weddell Sea embayment for the last three deglaciations. In December 2014 we conducted fieldwork to collect samples of rock and sediment debris carried by three of the major ice streams draining the Weddell Sea embayment: the Foundation Ice Stream, the Academy Glacier, and the Recovery Glacier. We sampled both modern moraines at the edges of the ice streams and older till on hillsides next to the ice streams. In addition to rocks representing the geology of local outcrops, we found that each of the three ice streams carries a characteristic set of erratic lithologies from further upstream, giving clues to the geology hidden under the ice sheet. Downstream, subglacial till and proximal glaciomarine sediment from existing core sites located at the edge of the Filchner and Ronne Ice Shelves, collected on past expeditions of the RV Polarstern, characterize the geochemical and geochronological fingerprint along ice flow lines extending from the ice streams. Finally, two deep-water RV Polarstern sites contain a continuous record of IRD sourced from the set of Weddell embayment ice streams over the last few glacial cycles. Here we present new 40Ar/39Ar hornblende and biotite thermochronological data from individual mineral grains, K-Ar from the silt fraction, and U-Pb zircon geochronology from the onshore tills and offshore sediments. Using this data we will discuss provenance matching between the IRD and the ice streams, and the possibilities for using provenance to understand ice sheet dynamics over the course of glacial cycles.

Meteorological Drivers of West Antarctic Ice Sheet and Ice Shelf Surface Melt

NASA Astrophysics Data System (ADS)

Scott, R. C.; Nicolas, J. P.; Bromwich, D. H.; Norris, J. R.; Lubin, D.

2017-12-01

We identify synoptic patterns and surface energy balance components driving warming and surface melting on the West Antarctic Ice Sheet (WAIS) and ice shelves using reanalysis and satellite remote sensing data from 1973-present. We have developed a synoptic climatology of atmospheric circulation patterns during the summer melt season using k-means cluster and composite analysis of daily 700-mb geopotential height and near-surface air temperature and wind fields from the ECMWF ERA-Interim reanalysis. Surface melt occurrence is detected in satellite passive microwave brightness temperature observations (K-band, horizontal polarization) beginning with the NASA Nimbus-5 Electrically Scanning Microwave Radiometer (ESMR) and continuing with its more familiar descendants SMMR, SSM/I and SSMIS. To diagnose synoptic precursors and physical processes driving surface melt we combine the circulation climatology and multi-decadal records of cloud cover with surface radiative fluxes from the Extended AVHRR Polar Pathfinder (APP-x) project. We identify three distinct modes of regional summer West Antarctic warming since 1979 involving anomalous ridging over West Antarctica (WA) and the Amundsen Sea (AS). During the 1970s, ESMR data reveal four extensive melt events on the Ross Sea sector of the WAIS also linked to AS blocking. We therefore define an Amundsen Sea Blocking Index (ASBI). The ASBI and synoptic circulation pattern occurrence frequencies are correlated with the tropical Pacific (ENSO) and high latitude Southern Annular Mode (SAM) indices and the West Antarctic melt index. Surface melt in WA is favored by enhanced downwelling infrared and turbulent sensible heat fluxes associated with intrusions of warm, moist marine air. Consistent with recent findings from the Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE), marine advection to the Ross sector is favored by El Niño conditions in the tropical Pacific and a negative SAM. We also find that El Niño-related blocking favors warming and melting on the marine-based ice streams draining from Wilkes Basin, East Antarctica.

The hydro- and multi-isotope geochemistry of iron-rich ground waters emerging at the southern Baltic Sea coast line

NASA Astrophysics Data System (ADS)

Lipka, Marko; Wu, Zijun; Escher, Peter; Struck, Ulrich; Dellwig, Olaf; Schafmeister, Maria; Böttcher*, Michael E.

2013-04-01

Iron-rich groundwater springs emerging at the shore zone of the southern Baltic Sea (BS; Site Meschendorf) were examined on a seasonal base for a period of about two years. Besides major, minor, and trace elements, stable isotopes of water (H-2, O-18), dissolved inorganic carbon (DIC; C-13), and sulfate (S-34) were analyzed. The stream bed sediment was extracted for the geochemistry of the newly formed precipitates and further characterized via SEM-EDAX. Subsequently, the hydrogeochemical results were subjected to a thermodynamic analysis via the PHREEQC speciation model. The springs emerge from small pits (about 60 cm diameter; up to 15cm depth). Surrounding sediments are sandy with gravels found at depth and corresponding high permeabilities. The positions of different springs on the shore zone were stable during the investigation period while the shape of the pits and the stream beds may vary due to wind- and wave-driven forces. Selected measurements of spring yield discharges close to 10 L/min. The H-2 and O-18 contents of the spring waters indicate the ground water to originate from relatively young mixed meteoric waters. The hydrochemistry of the springs was similar and showed some variability in between which indicates that the genetic processes for the ground water before reaching the surface may slightly differ. The springs are characterized by dissolved Ca, Mg, Na, DIC and sulfate, mainly reflecting the interaction with soils and bedrocks in the recharge area that is dominated by marly till. The oxygen-free ground water is rich in Fe, P, and DIC. Iron and dissolved sulfate originate from the oxidation of pyrite, as further confirmed by the 34-S signature of sulfate. The carbon isotope signature of DIC indicates a mixture of biogenic CO2 from the soil zone with some water-rock interaction with carbonate minerals. The streams flow towards the BS and, in contact with the atmosphere, outgas carbon dioxide and takes up oxygen. Upon CO2-degassing, C-12 is preferentially desorbed from the aqueous solution. The changes in the stream composition lead to the formation of iron(oxyhyr)oxide precipitates in the stream bed before the waters pass to underground drainage into a subterranean mixing zone with brackish BS waters. These ochrous precipitates act as a sink for dissolved phosphate and minor calcium. P : Fe ratios and Ca : Fe ratios are about 0.08 and 0.2, respectively, which are caused by P adsorption and a mixture with minor CaCO3 and/or Ca-phosphate. The investigation reveals that the surface precipitation on the beach leads to the formation of SGD essentially free of dissolved iron and strongly depleted in phosphate. Similar iron phases may also be an important part of the subterranean estuary supposed at that coast line, where retention of nutrients and heavy metals by iron(oxyhydr)oxides could influence the release of nutrients into the coastal ecosystem. Fe- and P-rich surface precipitates, however, are transported in suspension into the Baltic Sea during wind-driven flood events. Acknowledgements: This work was partly supported by the BONUS+ project AMBER and the Leibniz IOW.

Variability in Sea Surface Height: A Qualitative Measure for the Meridional Overturning in the North Atlantic

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa

1999-01-01

Sea surface height (SSH) from altimeter observations from 1992 on and from modeling results is investigated to determine the modes of variability and the linkages to the state of oceanic circulation in the North Atlantic. First the altimeter and model simulated SSH are analyzed using the empirical orthogonal function (EOF) analysis. They are found to share a similar leading mode where the center of action is along the Gulf Stream and North Atlantic Current with opposite sign anomalies in the subpolar gyre and in the slope waters along the Eastern Seaboard. The time series of the leading EOF mode from the altimeter data shows that between winters of 1995 and 1996, SSH over the Gulf Stream decreased by about 12cm which change is reproduced by the model simulation. Based on the relationship from the model simulations between the time series of the SSH EOF1 and meridional heat transport, it is suggested that associated with this SSH change in 1995-96, the overturning has slowed down from its heights in the early 90's. Furthermore, it is shown that decadal variability in the leading SSH mode originates from the thermal forcing component. This adds confidence to the qualitative relationship between the state of overturning/meridional heat transport and SSH in the limited area described by the EOF1. SSH variability in the eastern side of the North Atlantic basin, outside the western boundary current region, is determined by local and remote (Rossby waves) wind stress curl forcing.

Climate Drivers of Alaska Summer Stream Temperature

NASA Astrophysics Data System (ADS)

Bieniek, P.; Bhatt, U. S.; Plumb, E. W.; Thoman, R.; Trammell, E. J.

2016-12-01

The temperature of the water in lakes, rivers and streams has wide ranging impacts from local water quality and fish habitats to global climate change. Salmon fisheries in Alaska, a critical source of food in many subsistence communities, are sensitive to large-scale climate variability and river and stream temperatures have also been linked with salmon production in Alaska. Given current and projected climate change, understanding the mechanisms that link the large-scale climate and river and stream temperatures is essential to better understand the changes that may occur with aquatic life in Alaska's waterways on which subsistence users depend. An analysis of Alaska stream temperatures in the context of reanalysis, downscaled, station and other climate data is undertaken in this study to fill that need. Preliminary analysis identified eight stream observation sites with sufficiently long (>15 years) data available for climate-scale analysis in Alaska with one station, Terror Creek in Kodiak, having a 30-year record. Cross-correlation of summer (June-August) water temperatures between the stations are generally high even though they are spread over a large geographic region. Correlation analysis of the Terror Creek summer observations with seasonal sea surface temperatures (SSTs) in the North Pacific broadly resembles the SST anomaly fields typically associated with the Pacific Decadal Oscillation (PDO). A similar result was found for the remaining stations and in both cases PDO-like correlation patterns also occurred in the preceding spring. These preliminary results demonstrate that there is potential to diagnose the mechanisms that link the large-scale climate system and Alaska stream temperatures.

Horizontal mixing in the Southern Ocean from Argo float trajectories

NASA Astrophysics Data System (ADS)

Roach, Christopher J.; Balwada, Dhruv; Speer, Kevin

2016-08-01

We provide the first observational estimate of the circumpolar distribution of cross-stream eddy diffusivity at 1000 m in the Southern Ocean using Argo float trajectories. We show that Argo float trajectories, from the float surfacing positions, can be used to estimate lateral eddy diffusivities in the ocean and that these estimates are comparable to those obtained from RAFOS floats, where they overlap. Using the Southern Ocean State Estimate (SOSE) velocity fields to advect synthetic particles with imposed behavior that is "Argo-like" and "RAFOS-like" diffusivity estimates from both sets of synthetic particles agreed closely at the three dynamically very different test sites, the Kerguelen Island region, the Southeast Pacific Ocean, and the Scotia Sea, and support our approach. Observed cross-stream diffusivities at 1000 m, calculated from Argo float trajectories, ranged between 300 and 2500 m2 s-1, with peaks corresponding to topographic features associated with the Scotia Sea, the Kerguelen Plateau, the Campbell Plateau, and the Southeast Pacific Ridge. These observational estimates agree with previous regional estimates from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) near the Drake Passage, and other estimates from natural tracers (helium), inverse modeling studies, and current meter measurements. These estimates are also compared to the suppressed eddy diffusivity in the presence of mean flows. The comparison suggests that away from regions of strong topographic steering suppression explains both the structure and magnitude of eddy diffusivity but that eddy diffusivities in the regions of topographic steering are greater than what would be theoretically expected and the ACC experiences localized enhanced cross-stream mixing in these regions.

Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

NASA Technical Reports Server (NTRS)

Brunt, Kelly M.; MacAyeal, Douglas R.

2014-01-01

Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

Assessing trace metal pollution through high spatial resolution of surface sediments along the Tunis Gulf coast (southwestern Mediterranean).

PubMed

Ennouri, Rym; Zaaboub, Noureddine; Fertouna-Bellakhal, Mouna; Chouba, Lassad; Aleya, Lotfi

2016-03-01

Tunis Gulf (northern Tunisia, Mediterranean Sea) is of great economic importance due to its abundant fish resources. Rising urbanization and industrial development in the surrounding area have resulted in an increase in untreated effluents and domestic waste discharged into the gulf via its tributary streams. Metal (Cd, Pb, Hg, Cu, Zn, Fe, and Mn) and major element (Mg, Ca, Na, and K) concentrations were measured in the grain fine fraction <63 μm by atomic absorption spectrophotometry. Results showed varying spatial distribution patterns for metals, indicating complex origins and controlling factors such as anthropogenic activities. Sediment metal concentrations are ranked as follows: Fe > Mg > Zn > Mn > Pb > Cu > Cd > Hg. Metals tend to be concentrated in proximity to source points, suggesting that the mineral enrichment elements come from sewage of coastal towns and pollution from industrial dumps and located along local rivers, lagoons, and on the gulf shore itself. This study showed that trace metal and major element concentrations in surface sediments along the Tunis Gulf shores were lower than those found in other coastal areas of the Mediterranean Sea.

TOPEX/El Nino Watch - El Nino Warm Water Pool Decreasing, Jan, 08, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Jan. 8, 1998, and sea surface height is an indicator of the heat content of the ocean. The volume of the warm water pool related to the El Nino has decreased by about 40 percent since its maximum in early November, but the area of the warm water pool is still about one and a half times the size of the continental United States. The volume measurements are computed as the sum of all the sea surface height changes as compared to normal ocean conditions. In addition, the maximum water temperature in the eastern tropical Pacific, as measured by the National Oceanic and Atmospheric Administration (NOAA), is still higher than normal. Until these high temperatures diminish, the El Nino warm water pool still has great potential to disrupt global weather because the high water temperatures directly influence the atmosphere. Oceanographers believe the recent decrease in the size of the warm water pool is a normal part of El Nino's natural rhythm. TOPEX/Poseidon has been tracking these fluctuations of the El Nino warm pool since it began in early 1997. These sea surface height measurements have provided scientists with their first detailed view of how El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

Sediments in Arctic sea ice: Implications for entrainment, transport and release

USGS Publications Warehouse

Nurnberg, D.; Wollenburg, I.; Dethleff, D.; Eicken, H.; Kassens, H.; Letzig, T.; Reimnitz, E.; Thiede, Jorn

1994-01-01

Despite the Arctic sea ice cover's recognized sensitivity to environmental change, the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood. Sea ice sediment inclusions were studied in the central Arctic Ocean during the Arctic 91 expedition and in the Laptev Sea (East Siberian Arctic Region Expedition 1992). Results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central Arctic Ocean. This study documents the regional distribution and composition of particle-laden ice, investigates and evaluates processes by which sediment is incorporated into the ice cover, and identifies transport paths and probable depositional centers for the released sediment. In April 1992, sea ice in the Laptev Sea was relatively clean. The sediment occasionally observed was distributed diffusely over the entire ice column, forming turbid ice. Observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment. In the central Arctic Ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes. The surface sediment accumulation in central Arctic multi-year sea ice exceeds by far the amounts observed in first-year ice from the Laptev Sea in April 1992. Sea ice sediments are generally fine grained, although coarse sediments and stones up to 5 cm in diameter are observed. Component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles. The biogenous components, namely shells of pelecypods and benthic foraminiferal tests, point to a shallow, benthic, marine source area. Apparently, sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing. Clay mineralogy of ice-rafted sediments provides information on potential source areas. A smectite maximum in sea ice sediment samples repeatedly occurred between 81??N and 83??N along the Arctic 91 transect, indicating a rather stable and narrow smectite rich ice drift stream of the Transpolar Drift. The smectite concentrations are comparable to those found in both Laptev Sea shelf sediments and anchor ice sediments, pointing to this sea as a potential source area for sea ice sediments. In the central Arctic Ocean sea ice clay mineralogy is significantly different from deep-sea clay mineral distribution patterns. The contribution of sea ice sediments to the deep sea is apparently diluted by sedimentary material provided by other transport mechanisms. ?? 1994.

The Oleander Program - 9 years of Gulf Stream Sampling and Still Going Strong!

NASA Astrophysics Data System (ADS)

Rossby, T.

2001-12-01

Starting in Fall 1992 we have been monitoring the currents between the mid-Atlantic Bight and the NW Sargasso Sea with an acoustic Doppler current profiler on the freighter CMV Oleander, which makes weekly roundtrips between Port Elizabeth, NJ and Bermuda. In addition, XBTs and surface salts have been taken on a monthly basis since 1979. These systematic observations of the upper ocean are giving us new insights into the structure of the Gulf Stream and adjacent waters. In this overview we will highlight some of the major findings of this ongoing program. One of the more striking observations is perhaps the structural stability of the Gulf Stream itself. Its shape can be characterized as a double-exponential which results from the mixing or homogenization of waters between the current and either side, but not across it. We show that 80 percent of the Eulerian eddy kinetic energy that is observed in the Gulf Stream can be described in terms of the meandering of a rigid double-exponential current. The remaining variability can be accounted for in terms of a few structural modes that are most likely associated with the meandering of the current. We have found that the transport of the current has been conspicuously stable, and will argue that past thoughts about large variations in transport may result from an inability to distinguish between the current itself and adjacent local recirculations of varying intensity. The distinction is made clear thanks to the repeat sampling. However, the Gulf Stream does exhibit significant variations in mean path on interannual time scales. These show a strong correlation with temperature-salinity anomalies in the Slope Sea. We suggest that both result from time-varying transports from the Labrador shelf, but there is presently considerable discussion as to whether the path shifting should be viewed as a thermohaline or a winddriven process. More generally, we use the above examples to argue that with more deliberate planning, the unparalleled and repeat access to in-situ sampling of the oceans provided by commercial shipping and cruise vessels could provide society with far more extensive and valuable information about the ocean and atmospheric conditions at sea. But for this to happen, the instrumentation needs to be optimized for completely automatic and unattended operation. This also means working with the merchant marine community to develop guidelines and procedures for future cooperative efforts.

Ground-Water Occurrence and Contribution to Streamflow, Northeast Maui, Hawaii

USGS Publications Warehouse

Gingerich, Stephen B.

1999-01-01

The study area lies on the northern flank of the East Maui Volcano (Haleakala) and covers about 129 square miles between the drainage basins of Maliko Gulch to the west and Makapipi Stream to the east. About 989 million gallons per day of rainfall and 176 million gallons per day of fog drip reaches the study area and about 529 million gallons per day enters the ground-water system as recharge. Average annual ground-water withdrawal from wells totals only about 3 million gallons per day; proposed (as of 1998) additional withdrawals total about 18 million gallons per day. Additionally, tunnels and ditches of an extensive irrigation network directly intercept at least 10 million gallons per day of ground water. The total amount of average annual streamflow in gaged stream subbasins upstream of 1,300 feet altitude is about 255 million gallons per day and the total amount of average annual base flow is about 62 million gallons per day. Six major surface-water diversion systems in the study area have diverted an average of 163 million gallons per day of streamflow (including nearly all base flow of diverted streams) for irrigation and domestic supply in central Maui during 1925-97. Fresh ground water is found in two main forms. West of Keanae Valley, ground-water flow appears to be dominated by a variably saturated system. A saturated zone in the uppermost rock unit, the Kula Volcanics, is separated from a freshwater lens near sea level by an unsaturated zone in the underlying Honomanu Basalt. East of Keanae Valley, the ground-water system appears to be fully saturated above sea level to altitudes greater than 2,000 feet. The total average annual streamflow of gaged streams west of Keanae Valley is about 140 million gallons per day at 1,200 feet to 1,300 feet altitude. It is not possible to estimate the total average annual streamflow at the coast. All of the base flow measured in the study area west of Keanae Valley represents ground-water discharge from the high-elevation saturated zone. Total average daily ground-water discharge from the high-elevation saturated zone upstream of 1,200 feet altitude is greater than 38 million gallons per day, all of which is eventually removed from the streams by surface-water diversion systems. Perennial streamflow has been measured at altitudes greater than 3,000 feet in several of the streams. Discharge from the high-elevation saturated zone is persistent even during periods of little rainfall. The total average annual streamflow of the gaged streams east of Keanae Valley is about 109 million gallons per day at about 1,300 feet altitude. It is not possible to estimate the total average annual streamflow at the coast nor at higher altitudes. All of the base flow measured east of Keanae Valley represents ground-water discharge from the vertically extensive freshwater-lens system. Total average daily ground-water discharge to gaged streams upstream of 1,200 feet altitude is about 27 million gallons per day. About 19 million gallons per day of ground water discharges through the Kula and Hana Volcanics between about 500 feet and 1,300 feet altitude in the gaged stream sub-basins. About 13 million gallons per day of this discharge is in Hanawi Stream. The total ground-water discharge above 500 feet altitude in this part of the study area is greater than 56 million gallons per day.

Leatherback Turtle Movements, Dive Behavior, and Habitat Characteristics in Ecoregions of the Northwest Atlantic Ocean

PubMed Central

Dodge, Kara L.; Galuardi, Benjamin; Miller, Timothy J.; Lutcavage, Molly E.

2014-01-01

Leatherback sea turtles, Dermochelys coriacea, are highly migratory predators that feed exclusively on gelatinous zooplankton, thus playing a unique role in coastal and pelagic food webs. From 2007 to 2010, we used satellite telemetry to monitor the movements and dive behavior of nine adult and eleven subadult leatherbacks captured on the Northeast USA shelf and tracked throughout the Northwest Atlantic. Leatherback movements and environmental associations varied by oceanographic region, with slow, sinuous, area-restricted search behavior and shorter, shallower dives occurring in cool (median sea surface temperature: 18.4°C), productive (median chlorophyll a: 0.80 mg m−3), shallow (median bathymetry: 57 m) shelf habitat with strong sea surface temperature gradients (median SST gradient: 0.23°C km−1) at temperate latitudes. Leatherbacks were highly aggregated in temperate shelf and slope waters during summer, early fall, and late spring and more widely dispersed in subtropical and tropical oceanic and neritic habitat during late fall, winter and early spring. We investigated the relationship of ecoregion, satellite-derived surface chlorophyll, satellite-derived sea surface temperature, SST gradient, chlorophyll gradient and bathymetry with leatherback search behavior using generalized linear mixed-effects models. The most well supported model showed that differences in leatherback search behavior were best explained by ecoregion and regional differences in bathymetry and SST. Within the Northwest Atlantic Shelves region, leatherbacks increased path sinuosity (i.e., looping movements) with increasing SST, but this relationship reversed within the Gulf Stream region. Leatherbacks increased path sinuosity with decreasing water depth in temperate and tropical shelf habitats. This relationship is consistent with increasing epipelagic gelatinous zooplankton biomass with decreasing water depth, and bathymetry may be a key feature in identifying leatherback foraging habitat in neritic regions. High-use habitat for leatherbacks in our study occurred in coastal waters of the North American eastern seaboard and eastern Caribbean, putting turtles at heightened risk from land- and ocean-based human activity. PMID:24646920

Leatherback turtle movements, dive behavior, and habitat characteristics in ecoregions of the Northwest Atlantic Ocean.

PubMed

Dodge, Kara L; Galuardi, Benjamin; Miller, Timothy J; Lutcavage, Molly E

2014-01-01

Leatherback sea turtles, Dermochelys coriacea, are highly migratory predators that feed exclusively on gelatinous zooplankton, thus playing a unique role in coastal and pelagic food webs. From 2007 to 2010, we used satellite telemetry to monitor the movements and dive behavior of nine adult and eleven subadult leatherbacks captured on the Northeast USA shelf and tracked throughout the Northwest Atlantic. Leatherback movements and environmental associations varied by oceanographic region, with slow, sinuous, area-restricted search behavior and shorter, shallower dives occurring in cool (median sea surface temperature: 18.4°C), productive (median chlorophyll a: 0.80 mg m(-3)), shallow (median bathymetry: 57 m) shelf habitat with strong sea surface temperature gradients (median SST gradient: 0.23°C km(-1)) at temperate latitudes. Leatherbacks were highly aggregated in temperate shelf and slope waters during summer, early fall, and late spring and more widely dispersed in subtropical and tropical oceanic and neritic habitat during late fall, winter and early spring. We investigated the relationship of ecoregion, satellite-derived surface chlorophyll, satellite-derived sea surface temperature, SST gradient, chlorophyll gradient and bathymetry with leatherback search behavior using generalized linear mixed-effects models. The most well supported model showed that differences in leatherback search behavior were best explained by ecoregion and regional differences in bathymetry and SST. Within the Northwest Atlantic Shelves region, leatherbacks increased path sinuosity (i.e., looping movements) with increasing SST, but this relationship reversed within the Gulf Stream region. Leatherbacks increased path sinuosity with decreasing water depth in temperate and tropical shelf habitats. This relationship is consistent with increasing epipelagic gelatinous zooplankton biomass with decreasing water depth, and bathymetry may be a key feature in identifying leatherback foraging habitat in neritic regions. High-use habitat for leatherbacks in our study occurred in coastal waters of the North American eastern seaboard and eastern Caribbean, putting turtles at heightened risk from land- and ocean-based human activity.

Simulated variability of the Atlantic meridional overturning circulation

NASA Astrophysics Data System (ADS)

Bentsen, M.; Drange, H.; Furevik, T.; Zhou, T.

To examine the multi-annual to decadal scale variability of the Atlantic Meridional Overturning Circulation (AMOC) we conducted a four-member ensemble with a daily reanalysis forced, medium-resolution global version of the isopycnic coordinate ocean model MICOM, and a 300-years integration with the fully coupled Bergen Climate Model (BCM). The simulations of the AMOC with both model systems yield a long-term mean value of 18 Sv and decadal variability with an amplitude of 1-3 Sv. The power spectrum of the inter-annual to decadal scale variability of the AMOC in BCM generally follows the theoretical red noise spectrum, with indications of increased power near the 20-years period. Comparison with observational proxy indices for the AMOC, e.g. the thickness of the Labrador Sea Water, the strength of the baroclinic gyre circulation in the North Atlantic Ocean, and the surface temperature anomalies along the mean path of the Gulf Stream, shows similar trends and phasing of the variability, indicating that the simulated AMOC variability is robust and real. Mixing indices have been constructed for the Labrador, the Irminger and the Greenland-Iceland-Norwegian (GIN) seas. While convective mixing in the Labrador and the GIN seas are in opposite phase, and linked to the NAO as observations suggest, the convective mixing in the Irminger Sea is in phase with or leads the Labrador Sea. Newly formed deep water is seen as a slow, anomalous cold and fresh, plume flowing southward along the western continental slope of the Atlantic Ocean, with a return flow of warm and saline water on the surface. In addition, fast-travelling topographically trapped waves propagate southward along the continental slope towards equator, where they go east and continue along the eastern rim of the Atlantic. For both types of experiments, the Northern Hemisphere sea level pressure and 2 m temperature anomaly patterns computed based on the difference between climate states with strong and weak AMOC yields a NAO-like pattern with intensified Icelandic low and Azores high, and a warming of 0.25-0.5 °C of the central North Atlantic sea-surface temperature (SST). The reanalysis forced simulations indicate a coupling between the Labrador Sea Water production rate and an equatorial Atlantic SST index in accordance with observations. This coupling is not identified in the coupled simulation.

A back-pack shocker for collecting lamprey ammocoetes

USGS Publications Warehouse

Braem, Robert A.; Ebel, Wesley J.

1961-01-01

IN 1958, THE BUREAU OF COMMERCIAL FISHERIES began to use specific larvicides for sea lamprey control in streams tributary to the Great Lakes. The successful application of larvicides required treatment of all areas of the streams infested by sea lamprey ammocoetes. Intensive surveys were needed to determine distribution of the larvae. The use of electrical methods to determinelarval distribution has been described (Stauffer and Hansen 1958). A light portable shocker was needed for these surveys because of the difficulty of access to some of the watersheds tributary to Lake Superior.

Aerogeophysical evidence for active volcanism beneath the West Antarctic Ice Sheet

NASA Technical Reports Server (NTRS)

Blankenship, Donald D.; Bell, Robin E.; Hodge, Steven M.; Brozena, John M.; Behrendt, John C.

1993-01-01

Although it is widely understood that the collapse of the West Antarctic Ice Sheet (WAIS) would cause a global sea-level rise of 6 m, there continues to be considerable debate about the response of this ice sheet to climate change. The stability of the WAIS, which is characterized by a bed grounded well below sea level, may depend on geologically controlled conditions at the base, which are independent of climate. Ice streams moving up to 750 m/yr disperse material from the interior through to the oceans. As these ice streams tend to buffer the reservoir of slow-moving inland ice from exposure to oceanic degradation, understanding the ice-streaming process is important for evaluating WAIS stability. There is strong evidence that ice streams slide on a lubricating layer of water-saturated till. Development of this basal layer requires both water and easily eroded sediments. Active lithospheric extension may elevate regional heat flux, increase basal melting, and trigger ice streaming. If a geologically defined boundary with a sharp contrast in geothermal flux exists beneath the WAIS, ice streams may only be capable of operating as a buffer over a restricted region. Should ocean waters penetrate beyond this boundary, the ice-stream buffer would disappear, possibly triggering a collapse of the inland ice reservoir. Aerogeophysical evidence for active volcanism and elevated heat flux beneath the WAIS near the critical region where ice streaming begins is presented.

On the recovery of gravity anomalies from high precision altimeter data

NASA Technical Reports Server (NTRS)

Lelgemann, D.

1976-01-01

A model for the recovery of gravity anomalies from high precision altimeter data is derived which consists of small correction terms to the inverse Stokes' formula. The influence of unknown sea surface topography in the case of meandering currents such as the Gulf Stream is discussed. A formula was derived in order to estimate the accuracy of the gravity anomalies from the known accuracy of the altimeter data. It is shown that for the case of known harmonic coefficients of lower order the range of integration in Stokes inverse formula can be reduced very much.

Form and flow of the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian High Arctic

NASA Astrophysics Data System (ADS)

Dowdeswell, J. A.; Bassford, R. P.; Gorman, M. R.; Williams, M.; Glazovsky, A. F.; Macheret, Y. Y.; Shepherd, A. P.; Vasilenko, Y. V.; Savatyuguin, L. M.; Hubberten, H.-W.; Miller, H.

2002-04-01

The 5,575-km2 Academy of Sciences Ice Cap is the largest in the Russian Arctic. A 100-MHz airborne radar, digital Landsat imagery, and satellite synthetic aperture radar (SAR) interferometry are used to investigate its form and flow, including the proportion of mass lost through iceberg calving. The ice cap was covered by a 10-km-spaced grid of radar flight paths, and the central portion was covered by a grid at 5-km intervals: a total of 1,657 km of radar data. Digital elevation models (DEMs) of ice surface elevation, ice thickness, and bed elevation data sets were produced (cell size 500 m). The DEMs were used in the selection of a deep ice core drill site. Total ice cap volume is 2,184 km3 (~5.5 mm sea level equivalent). The ice cap has a single dome reaching 749 m. Maximum ice thickness is 819 m. About 200 km, or 42%, of the ice margin is marine. About 50% of the ice cap bed is below sea level. The central divide of the ice cap and several major drainage basins, in the south and east of the ice cap and of up to 975 km2, are delimited from satellite imagery. There is no evidence of past surge activity on the ice cap. SAR interferometric fringes and phase-unwrapped velocities for the whole ice cap indicate slow flow in the interior and much of the margin, punctuated by four fast flowing features with lateral shear zones and maximum velocity of 140 m yr-1. These ice streams extend back into the slower moving ice to within 5-10 km of the ice cap crest. They have lengths of 17-37 km and widths of 4-8 km. Mass flux from these ice streams is ~0.54 km3 yr-1. Tabular icebergs up to ~1.7 km long are produced. Total iceberg flux from the ice cap is ~0.65 km3 yr-1 and probably represents ~40% of the overall mass loss, with the remainder coming from surface melting. Driving stresses are generally lowest (<40 kPa) close to the ice cap divides and in several of the ice streams. Ice stream motion is likely to include a significant basal component and may involve deformable marine sediments.

Spin-Down of the North Atlantic Subpolar Circulation

NASA Technical Reports Server (NTRS)

Hakkinen, S.; Rhines, P. B.

2004-01-01

Dramatic changes have occurred in the mid-to-high-latitude North Atlantic Ocean as evidenced by TOPEX/Poseidon observations of sea surface height (SSH) in the subpolar gyre and the Gulf Stream. Analysis of altimeter data shows that subpolar SSH has increased during the 1990s and the geostrophic velocity derived from altimeter data shows a decline in the gyre circulation. Direct current-meter observations in the boundary current of the Labrador Sea support the trend in the 199Os, and, together with hydrographic data show that in the mid-late 1990s the trend extends deep in the water column. We find that buoyancy forcing over the northern North Atlantic has a dynamic effect consistent with the altimeter data and hydrographic observations: a weak thermohaline forcing and the subsequent decay of the domed structure of the subpolar isopycnals would give rise to the observed anticyclonic circulation trend.

Sea lamprey orient toward a source of a synthesized pheromone using odor-conditioned rheotaxis

USGS Publications Warehouse

Johnson, Nicholas S.; Muhammad, Azizah; Thompson, Henry; Choi, Jongeun; Li, Weiming

2012-01-01

Characterization of vertebrate chemo-orientation strategies over long distances is difficult because it is often not feasible to conduct highly controlled hypothesis-based experiments in natural environments. To overcome the challenge, we couple in-stream behavioral observations of female sea lampreys (Petromyzon marinus) orienting to plumes of a synthesized mating pheromone, 7a,12a,24-trihydroxy-5a-cholan-3-one-24-sulfate (3kPZS), and engineering algorithms to systematically test chemo-orientation hypotheses. In-stream field observations and simulated movements of female sea lampreys according to control algorithms support that odor-conditioned rheotaxis is a component of the mechanism used to track plumes of 3kPZS over hundreds of meters in flowing water. Simulated movements of female sea lampreys do not support that rheotaxis or klinotaxis alone is sufficient to enable the movement patterns displayed by females in locating 3kPZS sources in the experimental stream. Odor-conditioned rheotaxis may not only be effective at small spatial scales as previous described in crustaceans, but may also be effectively used by fishes over hundreds of meters. These results may prove useful for developing management strategies for the control of invasive species that exploit the odor-conditioned tracking behavior and for developing biologically inspired navigation strategies for robotic fish.

Titan's surface-atmosphere system before and after Huygens

NASA Astrophysics Data System (ADS)

Lunine, Jonathan I.

2015-04-01

Speculation about the nature of Titan's surface-atmosphere interactions goes back to the discovery of methane in its atmosphere in 1943 but beginning in the early 1970's surface models began to grapple more quantitatively with the source of methane and its instability in the atmosphere. The role of molecular nitrogen in the atmosphere was first quantitatively considered at that time as well. The Voyager 1 flyby put a thick atmosphere of molecular nitrogen and methane on an observational footing, and made an atmospheric descent probe quite feasible. The measured high methane humidity made seas of methane and possibly other constituents an attractive possible source of methane and sink of its photolytic products, influencing the choice of instruments for a descent probe. At the time of Huygens' actual descent to the surface, global seas had been ruled out, and the Cassini Orbiter was just beginning to gather imaging and radar data of the surface. The fluvial nature of the Huygens landing site and presence of volatiles just below the surface were important discoveries of Huygens itself. Together with Cassini, Huygens painted a picture of a cryogenic desert with occasional violent methane rainstorms feeding streams that tumble pebbles of ice and organics downhill, the whole surrounded by dunes whose organic-rich particles are harvested from the chemical conversion of methane to more refractory compounds high in the atmosphere. And yet many mysteries remain. The large bodies of liquid methane are restricted to high latitudes. Most of the river valleys seen in Cassini radar data seem to run down to nowhere. And the ultimate source and replenishment of methane, although seemingly more strongly tied to the interior than before Cassini-Huygens, remain unresolved. Huygens gave us the only imaging of Titan's surface with a resolution good enough to follow fluvial processes all the way from the contextual geology, to channels, to the stream debris washed out into the plains. What would we see if we could image even just 10% of Titan at Huygens resolution? Conversely, what might we have concluded about Titan were only the Cassini Orbiter data available, without Huygens? It is clear that Huygens gave us one tantalizing look through the keyhole at a mysterious room, but to truly understand what was glimpsed will require a future mission to open wide the door.

Multi-species coral Sr/Ca-based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits

USGS Publications Warehouse

Flannery, Jennifer A.; Richey, Julie N.; Thirumalai, Kaustubh; Poore, Richard Z.; DeLong, Kristine L.

2017-01-01

We present new, monthly-resolved Sr/Ca-based sea-surface temperature (SST) records from two species of massive coral, Orbicella faveolata and Siderastrea siderea, from the Dry Tortugas National Park, FL, USA (DTNP). We combine these new records with published data from three additional S. siderea coral colonies to generate a 278-year long multi-species stacked Sr/Ca-SST record from DTNP. The composite record of mean annual Sr/Ca-SST at DTNP shows pronounced decadal-scale variability with a range of 1 to 2°C. Notable cool intervals in the Sr/Ca-derived SST lasting about a decade centered at ~1845, ~1935, and ~1965 are associated with reduced summer Sr/Ca-SST (monthly maxima < 29°C), and imply a reduction in the spatial extent of the Atlantic Warm Pool (AWP). There is significant coherence between the composite DTNP Sr/Ca-SST record and the Atlantic Multidecadal Oscillation (AMO) index, with the AMO lagging Sr/Ca-SST at DTNP by 9 years. Low frequency variability in the Gulf Stream surface transport, which originates near DTNP, may provide a link for the lagged relationship between multidecadal variability at DTNP and the AMO.

Exploiting coastal altimetry to improve the surface circulation scheme over the central Mediterranean Sea

NASA Astrophysics Data System (ADS)

Jebri, Fatma; Birol, Florence; Zakardjian, Bruno; Bouffard, Jérome; Sammari, Cherif

2016-07-01

This work is the first study exploiting along track altimetry data to observe and monitor coastal ocean features over the transition area between the western and eastern Mediterranean Basins. The relative performances of both the AVISO and the X-TRACK research regional altimetric data sets are compared using in situ observations. Both products are cross validated with tide gauge records. The altimeter-derived geostrophic velocities are also compared with observations from a moored Acoustic Doppler Current Profiler. Results indicate the good potential of satellite altimetry to retrieve dynamic features over the area. However, X-TRACK shows a more homogenous data coverage than AVISO, with longer time series in the 50 km coastal band. The seasonal evolution of the surface circulation is therefore analyzed by conjointly using X-TRACK data and remotely sensed sea surface temperature observations. This combined data set clearly depicts different current regimes and bifurcations, which allows us to propose a new seasonal circulation scheme for the central Mediterranean. The analysis shows variations of the path and temporal behavior of the main circulation features: the Atlantic Tunisian Current, the Atlantic Ionian Stream, the Atlantic Libyan Current, and the Sidra Gyre. The resulting bifurcating veins of these currents are also discussed, and a new current branch is observed for the first time.

Response of wheat yield in Spain to large-scale patterns

NASA Astrophysics Data System (ADS)

Hernandez-Barrera, Sara; Rodriguez-Puebla, Concepcion

2016-04-01

Crops are vulnerable to extreme climate conditions as drought, heat stress and frost risk. In previous study we have quantified the influence of these climate conditions for winter wheat in Spain (Hernandez-Barrera et al. 2015). The climate extremes respond to large-scale atmospheric and oceanic patterns. Therefore, a question emerges in our investigation: How large-scale patterns affect wheat yield? Obtaining and understanding these relationships require different approaches. In this study, we first obtained the leading mode of observed wheat yield variability to characterize the common variability over different provinces in Spain. Then, the wheat variability is related to different modes of mean sea level pressure, jet stream and sea surface temperature by using Partial Least-Squares, which captures the relevant climate drivers accounting for variations in wheat yield from sowing to harvesting. We used the ERA-Interim reanalysis data and the Extended Reconstructed Sea Surface Temperature (SST) (ERSST v3b). The derived model provides insight about the teleconnections between wheat yield and atmospheric and oceanic circulations, which is considered to project the wheat yield trend under global warming using outputs of twelve climate models corresponding to the Coupled Models Intercomparison Project phase 5 (CMIP5). Hernandez-Barrera S., C. Rodríguez-Puebla and A.J. Challinor. Effects of diurnal temperature range and drought on wheat yield in Spain. Theoretical and Applied Climatology (submitted)

TOPEX/El Nino Watch - Warm Water Pool is Increasing, Nov. 10, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Nov. 10, 1997. The volume of extra warm surface water (shown in white) in the core of the El Nino continues to increase, especially in the area between 15 degrees south latitude and 15 degrees north latitude in the eastern Pacific Ocean. The area of low sea level (shown in purple) has decreased somewhat from late October. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 centimeters and 32 cm (6 inches to 13 inches) above normal; in the red areas, it is about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one-and-one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 to 30 degrees Celsius (70 to 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white areas) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmospheric system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Impingement of water droplets on wedges and diamond airfoils at supersonic speeds

NASA Technical Reports Server (NTRS)

Serafini, John S

1953-01-01

An analytical solution has been obtained for the equations of motion of water droplets impinging on a wedge in a two-dimensional supersonic flow field with a shock wave attached to the wedge. The closed-form solution yields analytical expressions for the equation of the droplet trajectory, the local rate of impingement and the impingement velocity at any point on the wedge surface, and the total rate of impingement. The analytical expressions are utilized to determine the impingement on the forward surfaces of diamond airfoils in supersonic flow fields with attached shock waves. The results presented include the following conditions: droplet diameters from 2 to 100 microns, pressure altitudes from sea level to 30,000 feet, free-stream static temperatures from 420 degrees to 460 degrees R. Also, free-stream Mach numbers from 1.1 to 2.0, semi-apex angles for the wedge from 1.14 degrees to 7.97 degrees, thickness-to-chord ratios for the diamond airfoil from 0.02 to 0.14, chord lengths from 1 to 20 feet, and angles of attack from zero to the inverse tangent of the airfoil thickness-to-chord ratio.

Reactivation of Kamb Ice Stream tributaries triggers century-scale reorganization of Siple Coast ice flow in West Antarctica

DOE PAGES

Bougamont, M.; Christoffersen, P.; Price, S. F.; ...

2015-10-21

Ongoing, centennial-scale flow variability within the Ross ice streams of West Antarctica suggests that the present-day positive mass balance in this region may reverse in the future. Here we use a three-dimensional ice sheet model to simulate ice flow in this region over 250 years. The flow responds to changing basal properties, as a subglacial till layer interacts with water transported in an active subglacial hydrological system. We show that a persistent weak bed beneath the tributaries of the dormant Kamb Ice Stream is a source of internal ice flow instability, which reorganizes all ice streams in this region, leadingmore » to a reduced (positive) mass balance within decades and a net loss of ice within two centuries. This hitherto unaccounted for flow variability could raise sea level by 5 mm this century. Furthermore, better constraints on future sea level change from this region will require improved estimates of geothermal heat flux and subglacial water transport.« less

Impact of beaver dams on abundance and distribution of anadromous salmonids in two lowland streams in Lithuania.

PubMed

Virbickas, Tomas; Stakėnas, Saulius; Steponėnas, Andrius

2015-01-01

European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction.

The role of local sea surface temperature pattern changes in shaping climate change in the North Atlantic sector

NASA Astrophysics Data System (ADS)

Hand, Ralf; Keenlyside, Noel S.; Omrani, Nour-Eddine; Bader, Jürgen; Greatbatch, Richard J.

2018-03-01

Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the winter-time response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model's atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum—or "warming hole"—in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of the local SST pattern changes on regions outside the North Atlantic is small in our setup.

Sea Surface Salinity Variability in Response to the Congo River Discharge

NASA Astrophysics Data System (ADS)

Moller, D.; Chao, Y.; Farrara, J. D.; Schumann, G.; Andreadis, K.

2014-12-01

Sea surface salinity (SSS) variability associated with the Congo River discharge is examined using Aquarius satellite-retrieved SSS data and vertical profiles of salinity measured by the Argo floats. The Congo River plume can be clearly identified in the Aquarius SSS data with a westward extension of 500 to 1000 km off the coast of the Democratic Republic of Congo (DRC). The peak amplitude of the SSS variability associated with the Congo River discharge exceeds 2.0 psu. Using the first two years of Aquarius data, a well-defined seasonal cycle is described: maximum fresh-water anomalies are found in the boreal winter and spring seasons. The fresh-water anomalies during the 2012-2013 winter and spring seasons are significantly fresher than the 2011-2012 winter and spring seasons. Vertical profiles of salinity derived from the Argo floats reveal that these fresh-water anomalies can be traced to 40 meters below the sea surface. Combining the Aquarius SSS data with the Argo vertical profiles of salinity, the 3D volume of these fresh-water anomalies can be inferred and used to estimate the Congo River discharge. Reasonably good agreement is found between the Congo River discharge as observed by a stream gauge at Kinshasa and that estimated from the combined Aquarius and Argo data, indicating that Aquarius data can be used to close the fresh-water budget between the coastal ocean and the Congo River. The precipitation minus evaporation portion of the freshwater flux is found to play a secondary role in this region.

Rapid Holocene thinning of outlet glaciers followed by readvance in the western Ross Embayment, Antarctica

NASA Astrophysics Data System (ADS)

Jones, R. S.; Whitmore, R.; Mackintosh, A.; Norton, K. P.; Eaves, S.; Stutz, J.

2017-12-01

Investigating Antarctic deglaciation following the LGM provides an opportunity to better understand patterns, mechanisms and drivers of ice sheet retreat. In the Ross Sea sector, geomorphic features preserved on the seafloor indicate that streaming East Antarctic outlet glaciers once extended >100 km offshore of South Victoria Land prior to back-stepping towards their modern configurations. In order to adequately interpret the style and causes of this retreat, the timing and magnitude of corresponding ice thickness change is required. We present new constraints on ice surface lowering from Mawson Glacier, an outlet of the East Antarctic Ice Sheet that flows into the western Ross Sea. Surface-exposure (10Be) ages from samples collected in elevation transects above the modern ice surface reveal that rapid thinning occurred at 5-8 ka, broadly coeval with new ages of grounding-line retreat at 6 ka and rapid thinning recorded at nearby Mackay Glacier at 7 ka. Our data also show that a moraine formed near to the modern ice margin of Mawson Glacier at 0.8 ka, which, together with historical observations, indicates that glaciers in this region readvanced during the last thousand years. We argue that 1) the accelerated thinning of outlet glaciers was driven by local grounding-line retreat through overdeepened basins during the early-mid Holocene, and 2) the glaciers subsequently readvanced, possibly linked to late Holocene sea-ice expansion, before retreating to their current positions. Our work demonstrates that these outlet glaciers were closely coupled to environmental and topography-induced perturbations near their termini throughout the Holocene.

Blocking and guiding adult sea lamprey with pulsed direct current from vertical electrodes

USGS Publications Warehouse

Johnson, Nicholas S.; Thompson, Henry T.; Holbrook, Christopher M.; Tix, John A.

2014-01-01

Controlling the invasion front of aquatic nuisance species is of high importance to resource managers. We tested the hypothesis that adult sea lamprey (Petromyzon marinus), a destructive invasive species in the Laurentian Great Lakes, would exhibit behavioral avoidance to dual-frequency pulsed direct current generated by vertical electrodes and that the electric field would not injure or kill sea lamprey or non-target fish. Laboratory and in-stream experiments demonstrated that the electric field blocked sea lamprey migration and directed sea lamprey into traps. Rainbow trout (Oncorhynchus mykiss) and white sucker (Catostomus commersoni), species that migrate sympatrically with sea lamprey, avoided the electric field and had minimal injuries when subjected to it. Vertical electrodes are advantageous for fish guidance because (1) the electric field produced varies minimally with depth, (2) the electric field is not grounded, reducing power consumption to where portable and remote deployments powered by solar, wind, hydro, or a small generator are feasible, and (3) vertical electrodes can be quickly deployed without significant stream modification allowing rapid responses to new invasions. Similar dual-frequency pulsed direct current fields produced from vertical electrodes may be advantageous for blocking or trapping other invasive fish or for guiding valued fish around dams.

Fluvial landscapes evolution in the Gangkou River basin of southern Taiwan: Evidence from the sediment cores

NASA Astrophysics Data System (ADS)

Chen, Jia-Hong; Chyi, Shyh-Jeng; Yen, Jiun-Yee; Lin, Li-Hung; Yen, I.-Chin; Yu, Neng-Ti; Ho, Lih-Der; Jen, Chia-Hung

2017-04-01

The Gangkou River basin is the largest basin in the eastern Hengchun Peninsula of Taiwan. Its main river length is 31km and the basin area is 102sq. km. The width of the active channel is relatively narrow, but the valley from the middle to downstream is remarkably wide, indicating a feature of underfit stream. We drilled two sediment cores in the downstream area, including a 30m core (core-A) from a higher terrace, which is 14m above mean sea level, and a 20m core (core-B) from a lower terrace, which is 4m above mean sea level. Most of the sediments in the core-A are mud, which represents the flood plain facies, and 14C dates in the core-A range from 11ka to 7ka BP. Furthermore, the sediment layers reveal signals of marine events at the core depths of 5m to 11m by X-ray fluorescence. In the core-B, there is an erosional surface at the core depth of 5m. The age of the fluvial gravel layer above the erosional surface is about 0.4ka BP, and the mud layer top the surface is about 8.5ka BP. The preliminary results show that (1) as the tectonic uplift rate induced by the marine terraces around the basin is 1.0 to 2.5 mm/yr, and the accumulation rate of the mud layer in the basin is 6.7 to 8.7 mm/yr, the sediments infilling (more than 30-meters-thick) in the downstream area of the basin should be the results of the lower tectonic uplifting and the higher post-glacial sea level rise and; (2) the marine sediment layer with 14C dates of 7.5ka to 8.5ka BP is very likely the remain of the maximum flooding surface (MFS) in the early Holocene. These results indicate that the fluvial landscapes evolution of the basin was controlled by the sea-level; (3) the erosional surface in the core-B indicates the Gangkou River continuously erode the infilling sediments from 7ka to 0.4ka BP. Previous studies show that the sea-level around Taiwan gradually declined from its high stand since 6ka, we proposed that the continuous erosion was probably the results of tectonic uplifting and eustatic sea-level fall.

Deglacial history of the Pensacola Mountains, Antarctica from glacial geomorphology and cosmogenic nuclide surface exposure dating

NASA Astrophysics Data System (ADS)

Bentley, M. J.; Hein, A. S.; Sugden, D. E.; Whitehouse, P. L.; Shanks, R.; Xu, S.; Freeman, S. P. H. T.

2017-02-01

The retreat history of the Antarctic Ice Sheet is important for understanding rapid deglaciation, as well as to constrain numerical ice sheet models and ice loading models required for glacial isostatic adjustment modelling. There is particular debate about the extent of grounded ice in the Weddell Sea embayment at the Last Glacial Maximum, and its subsequent deglacial history. Here we provide a new dataset of geomorphological observations and cosmogenic nuclide surface exposure ages of erratic samples that constrain the deglacial history of the Pensacola Mountains, adjacent to the present day Foundation Ice Stream and Academy Glacier in the southern Weddell Sea embayment. We show there is evidence of at least two glaciations, the first of which was relatively old and warm-based, and a more recent cold-based glaciation. During the most recent glaciation ice thickened by at least 450 m in the Williams Hills and at least 380 m on Mt Bragg. Progressive thinning from these sites was well underway by 10 ka BP and ice reached present levels by 2.5 ka BP, and is broadly similar to the relatively modest thinning histories in the southern Ellsworth Mountains. The thinning history is consistent with, but does not mandate, a Late Holocene retreat of the grounding line to a smaller-than-present configuration, as has been recently hypothesized based on ice sheet and glacial isostatic modelling. The data also show that clasts with complex exposure histories are pervasive and that clast recycling is highly site-dependent. These new data provide constraints on a reconstruction of the retreat history of the formerly-expanded Foundation Ice Stream, derived using a numerical flowband model.

Mesoscale Air-Sea Interactions along the Gulf Stream: An Eddy-Resolving and Convection-Permitting Coupled Regional Climate Model Study

NASA Astrophysics Data System (ADS)

Hsieh, J. S.; Chang, P.; Saravanan, R.

2017-12-01

Frontal and mesoscale air-sea interactions along the Gulf Stream (GS) during boreal winter are investigated using an eddy-resolving and convection-permitting coupled regional climate model with atmospheric grid resolutions varying from meso-β (27-km) to -r (9-km and 3-km nest) scales in WRF and a 9-km ocean model (ROMS) that explicitly resolves the ocean mesoscale eddies across the North Atlantic basin. The mesoscale wavenumber energy spectra for the simulated surface wind stress and SST demonstrate good agreement with the observed spectra calculated from the observational QuikSCAT and AMSR-E datasets, suggesting that the model well captures the energy cascade of the mesoscale eddies in both the atmosphere and the ocean. Intercomparison among different resolution simulations indicates that after three months of integration the simulated GS path tends to overshoot beyond the separation point in the 27-km WRF coupled experiments than the observed climatological path of the GS, whereas the 3-km nested and 9-km WRF coupled simulations realistically simulate GS separation. The GS overshoot in 27-km WRF coupled simulations is accompanied with a significant SST warming bias to the north of the GS extension. Such biases are associated with the deficiency of wind stress-SST coupling strengths simulated by the coupled model with a coarser resolution in WRF. It is found that the model at 27-km grid spacing can approximately simulate 72% (62%) of the observed mean coupling strength between surface wind stress curl (divergence) and crosswind (downwind) SST gradient while by increasing the WRF resolutions to 9 km or 3 km the coupled model can much better capture the observed coupling strengths.

Evidence for early metamorphosis of sea lampreys in the Chippewa River, Michigan

USGS Publications Warehouse

Morkert, Sidney B.; Swink, William D.; Seelye, James G.

1998-01-01

We determined age at metamorphosis to the juvenile or parasitic phase for sea lampreysPetromyzon marinus in a highly productive Great Lakes tributary to determine if the age at metamorphosis was earlier than expected. Ages determined from statoliths, a structure analogous to otoliths in teleost fishes, indicated that many sea lampreys collected from the Chippewa River, Michigan, in September 1995 were undergoing metamorphosis at age 2, at least 1 year earlier than previously observed. In all, 141 newly metamorphosed lampreys were examined, and 81% were estimated to be only 2 years old. The length-frequency distribution of newly metamorphosed sea lampreys in the Chippewa River also indicated the possibility of metamorphsis at age 2, but to a lesser extent than indicated by statolith aging. The Chippewa River is a highly productive stream that might require more frequent treatment than previously suspected. More careful examination of other highly productive streams is needed to determine if, and to what extent, sea lampreys metamorphose at age 2 in the Chippewa River and other Great Lakes tributaries.

Emerald oil field on production in North Sea

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

Not Available

1992-08-31

This paper reports that Midland and Scottish Energy Ltd. (MSE) has placed Emerald oil field on stream in the U.K. North Sea with a floating production unit. Initial production, from two satellite wells, will be used to commission facilities. Three water injection wells have been unplugged and are ready for start-up. MSE will place a central cluster of wells-five producers and one water injector-on stream during the next few weeks. Production will build to an expected 25,000 b/d from 35 million bbl of reserves. Field development has undergone an unusually large number of setbacks and changes.

Constraining the Antarctic contribution to global sea-level change: ANDRILL and beyond

NASA Astrophysics Data System (ADS)

Naish, Timothy

2016-04-01

Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1 to 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the scientific challenges, some potential sub-glacial sedimentary targets, and a strategy for future drilling of sub-glacial sedimentary basins.

Constraining the Antarctic contribution to interglacial sea-level rise

NASA Astrophysics Data System (ADS)

Naish, T.; Mckay, R. M.; Barrett, P. J.; Levy, R. H.; Golledge, N. R.; Deconto, R. M.; Horgan, H. J.; Dunbar, G. B.

2015-12-01

Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1- 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the scientific challenges, some potential sub-glacial sedimentary targets, and a strategy for future drilling of sub-glacial sedimentary basins.

Active volcanism beneath the West Antarctic ice sheet and implications for ice-sheet stability

USGS Publications Warehouse

Blankenship, D.D.; Bell, R.E.; Hodge, S.M.; Brozena, J.M.; Behrendt, John C.; Finn, C.A.

1993-01-01

IT is widely understood that the collapse of the West Antarctic ice sheet (WAIS) would cause a global sea level rise of 6 m, yet there continues to be considerable debate about the detailed response of this ice sheet to climate change1-3. Because its bed is grounded well below sea level, the stability of the WAIS may depend on geologically controlled conditions at the base which are independent of climate. In particular, heat supplied to the base of the ice sheet could increase basal melting and thereby trigger ice streaming, by providing the water for a lubricating basal layer of till on which ice streams are thought to slide4,5. Ice streams act to protect the reservoir of slowly moving inland ice from exposure to oceanic degradation, thus enhancing ice-sheet stability. Here we present aerogeophysical evidence for active volcanism and associated elevated heat flow beneath the WAIS near the critical region where ice streaming begins. If this heat flow is indeed controlling ice-stream formation, then penetration of ocean waters inland of the thin hot crust of the active portion of the West Antarctic rift system could lead to the disappearance of ice streams, and possibly trigger a collapse of the inland ice reservoir.

Erosion and deposition on a beach raised by the 1964 earthquake, Montague Island, Alaska: Chapter H in The Alaska earthquake, March 27, 1964: regional effects

USGS Publications Warehouse

Kirkby, M.J.; Kirkby, Anne V.

1969-01-01

During the 1964 Alaska earthquake, tectonic deformation uplifted the southern end of Montague Island as much as 33 feet or more. The uplifted shoreline is rapidly being modified by subaerial and marine processes. The new raised beach is formed in bedrock, sand, gravel, and deltaic bay-head deposits, and the effect of each erosional process was measured in each material. Fieldwork was concentrated in two areas—MacLeod Harbor on the northwest side and Patton Bay on the southeast side of Montague Island. In the unconsolidated deltaic deposits of MacLeod Harbor, 97 percent of the erosion up to June 1965, 15 months after the earthquake, was fluvial, 2.2 percent was by rainwash, and only 0.8 percent was marine; 52 percent of the total available raised beach material had already been removed. The volume removed by stream erosion was proportional to low-flow discharge raised to the power of 0.75 to 0.95, and this volume increased as the bed material became finer. Stream response to the relative fall in base level was very rapid, most of the downcutting in unconsolidated materials occurring within 48 hours of the uplift for streams with low flows greater than 10 cubic feet per second. Since then, erosion by these streams has been predominantly lateral. Streams with lower discharges, in unconsolidated materials, still had knickpoints after 15 months. No response to uplift could be detected in stream courses above the former preearthquake sea level. Where the raised beach is in bedrock, it is being destroyed principally by marine action but at such a low rate that no appreciable erosion of bedrock was found 15 months after the earthquake. A dated rock platform raised earlier has eroded at a mean rate of 0.49 foot per year. In this area the factor limiting the rate of erosion was rock resistance rather than the transporting capacity of the waves. The break in slope between the top of the raised beach and the former seacliff is being obliterated by debris which is accumulating at the base of the cliffs and which is no longer being removed by the sea. Current cliff retreat by rockfall, mudflows, and landslides was estimated at 0.7 to 2.0 feet per year, and in parts of Patton Bay the accumulation of debris has obliterated 78 percent of the original break in slope in 15 months. Evidence of two relative sea-level changes before 1964 was found in Patton Bay. At a high stand of sea level lasting until about 2000 B.P. (before present), an older raised beach was formed which, over a distance of 5 miles, shows 40 feet of deformation relative to the present sea level. Peat deposits exposed by the 1964 uplift also record a low sea level that lasted until at least 600 B.P. The 1964 raised beach was used to test the accuracy of identification of former sea-level elevations from raised beach features. The Pre-1964 sea level could be accurately determined from the height of the former barnacle line, so an independent check on high-water level was available. The most reliable topographic indicator was the elevation of the break in slope at the top of a beach between a bedrock platform and a cliff. Even here, the former sea level could only be identified within 5 feet. The breaks in slope at the top of gravel beaches were found to be poor indicators of former sea level. On Montague Island, evidence of former high sea levels appeared to be best preserved (1) as raised bedrock platforms on rocks of moderate resistance in slightly sheltered locations and (2) as raised storm beaches where the relief immediately inland was very low.

Another look at North Sea pole tide dynamics

NASA Technical Reports Server (NTRS)

Dickman, S. R.; Preisig, J. R.

1986-01-01

The mechanism proposed by Wunsch (1974) to explain pole tide observations in the North Sea is evaluated. Wunsch's equations governing pole tide in the North Sea are presented, and solutions for correcting the depth, stream function, and deviation of the tidal height from the equilibrium values are described. The similarity between the Stokes paradox and the tidal equations of the North Sea, and the need for inclusion of inertial terms in the tidal equations are discussed.

Long river profiles, tectonism, and eustasy: A guide to interpreting fluvial terraces

NASA Technical Reports Server (NTRS)

Merritts, Dorothy J.; Vincent, Kirk R.; Wohl, Ellen E.

1994-01-01

Along three rivers at the Mendocino triple junction, northern California, strath, cut, and fill terraces have formed in response to tectonic and eustatic processes. Detailed surveying and radiometric dating at multiple sites indicate that lower reaches of the rivers are dominated by the effects of oscillating sea level, primarily aggradation and formation of fill terraces during sea level high stands, alternating with deep incision during low stands. A eustasy-driven depositional wedge extends tens of kilometers upstream on all rivers (tapering to zero thickness). This distance is greater than expected from studies of the effects of check dams on much smaller streams elsewhere, due in part to the large size of these rivers. However, the change in gradient is nearly identical to other base level rise studies: the depositional gradient is about half that of the original channel. Middle to upper reaches of each river are dominated by the effects of long-term uplift, primarily lateral and vertical erosion and formation of steep, unpaired strath terraces exposed only upstream of the depositional wedge. Vertical incision at a rate similar to that of uplift has occurred even during the present sea level high stand along rivers with highest uplift rates. Strath terraces have steeper gradients than the modern channel bed and do not merge with marine terraces at the river mouth; consequently, they cannot be used to determine altitudes of sea level high stands. Strath formation is a continuous process of response to long-term uplift, and its occurrence varies spatially along a river depending on stream power, and hence position, upstream. Strath terraces are found only along certain parts of a coastal stream: upstream of the aggradational effects of oscillating sea level, and far enough downstream that stream power is in excess of that needed to transport the prevailing sediment load. For a given size river, the greater the uplift rate, the greater the rate of vertical incision and, consequently, the less the likelihood of strath terrace formation and preservation.

Teleconnection between sea ice in the Barents Sea in June and the Silk Road, Pacific-Japan and East Asian rainfall patterns in August

NASA Astrophysics Data System (ADS)

He, Shengping; Gao, Yongqi; Furevik, Tore; Wang, Huijun; Li, Fei

2018-01-01

In contrast to previous studies that have tended to focus on the influence of the total Arctic sea-ice cover on the East Asian summer tripole rainfall pattern, the present study identifies the Barents Sea as the key region where the June sea-ice variability exerts the most significant impacts on the East Asian August tripole rainfall pattern, and explores the teleconnection mechanisms involved. The results reveal that a reduction in June sea ice excites anomalous upward air motion due to strong near-surface thermal forcing, which further triggers a meridional overturning wave-like pattern extending to midlatitudes. Anomalous downward motion therefore forms over the Caspian Sea, which in turn induces zonally oriented overturning circulation along the subtropical jet stream, exhibiting the east-west Rossby wave train known as the Silk Road pattern. It is suggested that the Bonin high, a subtropical anticyclone predominant near South Korea, shows a significant anomaly due to the eastward extension of the Silk Road pattern to East Asia. As a possible descending branch of the Hadley cell, the Bonin high anomaly ultimately triggers a meridional overturning, establishing the Pacific-Japan pattern. This in turn induces an anomalous anticyclone and cyclone pair over East Asia, and a tripole vertical convection anomaly meridionally oriented over East Asia. Consequently, a tripole rainfall anomaly pattern is observed over East Asia. Results from numerical experiments using version 5 of the Community Atmosphere Model support the interpretation of this chain of events.

Teleconnection between Sea Ice in the Barents Sea in June and the Silk Road, Pacific-Japan and East Asian Rainfall Patterns in August

NASA Astrophysics Data System (ADS)

He, S.; Gao, Y.; Furevik, T.; Huijun, W.; Li, F.

2017-12-01

In contrast to previous studies that have tended to focus on the influence of the total Arctic sea-ice cover on the East Asian summer tripole rainfall pattern, the present study identifies the Barents Sea as the key region where the June sea-ice variability exerts the most significant impacts on the East Asian August tripole rainfall pattern, and explores the teleconnection mechanisms involved. The results reveal that a reduction in June sea ice excites anomalous upward air motion due to strong near-surface thermal forcing, which further triggers a meridional overturning wave-like pattern extending to midlatitudes. Anomalous downward motion therefore forms over the Caspian Sea, which in turn induces zonally oriented overturning circulation along the subtropical jet stream, exhibiting the east-west Rossby wave train known as the Silk Road pattern. It is suggested that the Bonin high, a subtropical anticyclone predominant near South Korea, shows a significant anomaly due to the eastward extension of the Silk Road pattern to East Asia. As a possible descending branch of the Hadley cell, the Bonin high anomaly ultimately triggers a meridional overturning, establishing the Pacific-Japan pattern. This in turn induces an anomalous anticyclone and cyclone pair over East Asia, and a tripole vertical convection anomaly meridionally oriented over East Asia. Consequently, a tripole rainfall anomaly pattern is observed over East Asia. Results from numerical experiments using version 5 of the Community Atmosphere Model support the interpretation of this chain of events.

Regional sea level variability in a high-resolution global coupled climate model

NASA Astrophysics Data System (ADS)

Palko, D.; Kirtman, B. P.

2016-12-01

The prediction of trends at regional scales is essential in order to adapt to and prepare for the effects of climate change. However, GCMs are unable to make reliable predictions at regional scales. The prediction of local sea level trends is particularly critical. The main goal of this research is to utilize high-resolution (HR) (0.1° resolution in the ocean) coupled model runs of CCSM4 to analyze regional sea surface height (SSH) trends. Unlike typical, lower resolution (1.0°) GCM runs these HR runs resolve features in the ocean, like the Gulf Stream, which may have a large effect on regional sea level. We characterize the variability of regional SSH along the Atlantic coast of the US using tide gauge observations along with fixed radiative forcing runs of CCSM4 and HR interactive ensemble runs. The interactive ensemble couples an ensemble mean atmosphere with a single ocean realization. This coupling results in a 30% decrease in the strength of the Atlantic meridional overturning circulation; therefore, the HR interactive ensemble is analogous to a HR hosing experiment. By characterizing the variability in these high-resolution GCM runs and observations we seek to understand what processes influence coastal SSH along the Eastern Coast of the United States and better predict future SLR.

Environmental Guide to the Virginia Capes Operating Area

DTIC Science & Technology

1973-03-01

invertebrates occupy the waters over the shelf. Among fishes found here are croakers, sea robins, sea bass, sharks, rays, bluefish , alewives, and...pelagic forms such as tuna, billfish, and bluefish migrate seasonally, occurring in greatest abun- dance along the Gulf Stream boundary in spring and

Ice dynamics of Heinrich events: Insights and implications

NASA Astrophysics Data System (ADS)

Alley, R. B.; Parizek, B. R.; Anandakrishnan, S.

2017-12-01

Physical understanding of ice flow provides important constraints on Heinrich (H) events, which in turn provide lessons for ice dynamics and future sea-level change. Iceberg-rafted debris (IRD), the defining feature of H events, is a complex indicator; however, in cold climates with extensive marine-ending ice, increased IRD flux records ice-shelf loss. Ice shelves fed primarily by inflow from grounded ice experience net basal melting, giving sub-ice-sedimentation rather than open-ocean IRD. Ice-shelf loss has been observed recently in response to atmospheric warming increasing surface meltwater that wedged open crevasses (Larsen B), but also by break-off following thinning from warming of waters reaching the grounding line (Jakobshavn). The H events consistently occurred during cold times resulting from reduced North Atlantic overturning circulation ("conveyor"), but as argued by Marcott et al. (PNAS 2011), this was accompanied by delayed warming at grounding-line depths of the Hudson Strait ice stream, the source of the Heinrich layers, implicating oceanic control. As shown in a rich literature, additional considerations involving thermal state of the ice-stream bed, isostasy and probably other processes influenced why some reduced-conveyor events triggered H-events while others did not. Ice shelves, including the inferred Hudson Strait ice shelf, typically exist in high-salinity, cold waters produced by brine rejection from sea-ice formation, which are the coldest abundant waters in the world ocean. Thus, almost any change in air or ocean temperature, winds or currents can remove ice shelves, because "replacement" water masses are typically warmer. And, because ice shelves almost invariably slow flow of non-floating ice into the ocean, climatic perturbations to regions with ice shelves typically lead to sea-level rise, with important implications.

Streaming potential generated by a pressure-driven flow over a super-hydrophobic surface

NASA Astrophysics Data System (ADS)

Zhao, Hui

2010-11-01

The streaming potential generated by a pressured-driven flow over a weakly charged striped slip-stick surface (the zeta potential of the surface is smaller than the thermal potential (25 mV) with an arbitrary double layer thickness is theoretically studied by solving the Poisson-Boltzmann equation and Stokes equation. A series solution of the streaming potential is derived. Approximate expressions for the streaming potential in the limits of thin double layers and thick double layers are also presented, in excellent agreement with the full solution. The streaming potential is compared against that over a homogenously charged smooth surface. Our results indicate that the streaming potential over a super-hydrophobic surface only can be enhanced when the liquid-gas interface is charged. In addition, as the double layer thickness increases, the advantage of the super-hydrophobic surface diminishes. The impact of a slip-stick surface on the streaming potential might provide guidance for designing novel and efficient microfludic energy conversion devices using a super-hydrophobic surface.

How can present and future satellite missions support scientific studies that address ocean acidification?

USGS Publications Warehouse

Salisbury, Joseph; Vandemark, Douglas; Jonsson, Bror; Balch, William; Chakraborty, Sumit; Lohrenz, Steven; Chapron, Bertrand; Hales, Burke; Mannino, Antonio; Mathis, Jeremy T.; Reul, Nicolas; Signorini, Sergio; Wanninkhof, Rik; Yates, Kimberly K.

2016-01-01

Space-based observations offer unique capabilities for studying spatial and temporal dynamics of the upper ocean inorganic carbon cycle and, in turn, supporting research tied to ocean acidification (OA). Satellite sensors measuring sea surface temperature, color, salinity, wind, waves, currents, and sea level enable a fuller understanding of a range of physical, chemical, and biological phenomena that drive regional OA dynamics as well as the potentially varied impacts of carbon cycle change on a broad range of ecosystems. Here, we update and expand on previous work that addresses the benefits of space-based assets for OA and carbonate system studies. Carbonate chemistry and the key processes controlling surface ocean OA variability are reviewed. Synthesis of present satellite data streams and their utility in this arena are discussed, as are opportunities on the horizon for using new satellite sensors with increased spectral, temporal, and/or spatial resolution. We outline applications that include the ability to track the biochemically dynamic nature of water masses, to map coral reefs at higher resolution, to discern functional phytoplankton groups and their relationships to acid perturbations, and to track processes that contribute to acid variation near the land-ocean interface.

Earth observations taken by the Expedition 14 crew

NASA Image and Video Library

2006-11-10

ISS014-E-07738 (10 Nov. 2006) --- This image featuring a southeast-looking view of the Long Island Sound and New Jersey coast, with the lower Hudson River and New York Bay in the area of brightest sunglint was photographed by an Expedition 14 crewmember on the International Space Station. On the far right a gray haze can be seen streaming out to sea offshore of New Jersey, where it becomes harder to see. In fact haze covers most of the visible area offshore, partly obscuring the sea surface. By contrast, clouds look quite different from haze according to scientists. Clouds usually have sharp margins and are pure white, as clouds at the bottom show. Industrial haze is grayer and more diffuse, and is typical of the air over the Northeast. Flow lines show that winds are transporting the haze in clockwise fashion--i.e. bending south--which in turn signifies that a high pressure system was operating on that day, centered roughly over the coast. High pressure systems are notorious for promoting smog events because they bring clear skies, and sunlight promotes smog formation. Highs also concentrate polluted surface layers near the ground.

Potentiometric Surface of the Alluvial Aquifer and Hydrologic Conditions in the Juana Diaz area, Puerto Rico, June 29 - July 1, 2005

USGS Publications Warehouse

Rodriguez, Jose M.; Santigo-Rivera, Luis; Gómez-Gómez, Fernando

2006-01-01

A synoptic survey of the hydrologic conditions in the Juana Diaz area, Puerto Rico, was conducted between June 29 and July 1, 2005, to define the spatial distribution of the potentiometric surface of the alluvial aquifer. The study area encompasses 21 square miles of the more extensive South Coastal Plain Alluvial Aquifer system and is bounded along the north by foothills of the Cordillera Central mountain chain, to the south by the Caribbean Sea, the east by the Rio Descalabrado and to the west by the Rio Inabon. Ground water in the Juana Diaz area is in the Quaternary-age alluvial deposits and the middle-Tertiary age Ponce Limestone and Juana Diaz Formation (Giusti, 1968). The hydraulic properties of the Ponce Limestone in the Juana Diaz area are unknown, and the Juana Diaz Formation is a unit of poor permeability due to its high clay content. Consequently, the Ponce Limestone and the Juana Diaz Formation are generally considered to be the base of the alluvial aquifer in the Juana Diaz area with ground-water flow occurring primarily within the alluvial deposits. The potentiometric-surface map of the alluvial aquifer was delineated using ground-water level measurements taken at existing wells. The water-level measurements were taken at wells that were either not pumping during the survey or were shut down for a brief period. In the latter case, a recovery period of 30 minutes was allowed for the drawdown in the wellbore to achieve a near static level position representative of the aquifer at the measurement point. Land-surface altitude from U.S. Geological Survey (USGS) 1:20,000 scale topographic maps (Playa de Ponce, Ponce, Rio Descalabrado, and Santa Isabel) were used to refer ground-water levels to mean sea level datum (National Geodetic Vertical Datum of 1929). In addition to the ground-water level measurements, the potentiometricsurface contours were delineated using hydrologic features, such as drainage ditches and saturated intermittent streams that were considered as aquifer drains and losing streams, respectively.

Numerical study of electromagnetic scattering from one-dimensional nonlinear fractal sea surface

NASA Astrophysics Data System (ADS)

Xie, Tao; He, Chao; William, Perrie; Kuang, Hai-Lan; Zou, Guang-Hui; Chen, Wei

2010-02-01

In recent years, linear fractal sea surface models have been developed for the sea surface in order to establish an electromagnetic backscattering model. Unfortunately, the sea surface is always nonlinear, particularly at high sea states. We present a nonlinear fractal sea surface model and derive an electromagnetic backscattering model. Using this model, we numerically calculate the normalized radar cross section (NRCS) of a nonlinear sea surface. Comparing the averaged NRCS between linear and nonlinear fractal models, we show that the NRCS of a linear fractal sea surface underestimates the NRCS of the real sea surface, especially for sea states with high fractal dimensions, and for dominant ocean surface gravity waves that are either very short or extremely long.

Geology of the Arabian Peninsula; shield area of western Saudi Arabia

USGS Publications Warehouse

Brown, Glen F.; Schmidt, Dwight L.; Huffman, A. Curtis

1989-01-01

A second stage of sea-floor spreading about 4-5 m.y. produced the Red Sea axial trough, consisting of oceanic crust, as well as renewed uplift and tilting of the three tectonic provinces in response to compression from counterclockwise rotation against the Dead Sea Rift. This late movement caused widespread major stream capture, especially along the wadis that formerly drained southwesterly or northwesterly, the channels turning westward through narrow gorges to the coastal plain and the Red Sea.

Survival and metamorphosis of low-density populations of larval sea lampreys (Petromyzon marinus) in streams following lampricide treatment

USGS Publications Warehouse

Johnson, Nicholas S.; Swink, William D.; Brenden, Travis O.; Slade, Jeffrey W.; Steeves, Todd B.; Fodale, Michael F.; Jones, Michael L.

2014-01-01

Sea lamprey Petromyzon marinus control in the Great Lakes primarily involves application of lampricides to streams where larval production occurs to kill larvae prior to their metamorphosing and entering the lakes as parasites (juveniles). Because lampricides are not 100% effective, larvae that survive treatment maymetamorphose before streams are again treated. Larvae that survive treatment have not beenwidely studied, so their dynamics are notwell understood.Wetagged and released larvae in six Great Lake tributaries following lampricide treatment and estimated vital demographic rates using multistate tag-recovery models. Model-averaged larval survivals ranged from 56.8 to 57.6%. Model-averaged adult recovery rates, which were the product of juvenile survivals and adult capture probabilities, ranged from 6.8 to 9.3%. Using stochastic simulations, we estimated production of juvenile sea lampreys from a hypothetical population of treatment survivors under different growth conditions based on parameter estimates from this research. For fast-growing populations, juvenile production peaked 2 years after treatment. For slow-growing populations, juvenile production was approximately one-third that of fast-growing populations,with production not peaking until 4 years after treatment. Our results suggest that dynamics (i.e., survival, metamorphosis) of residual larval populations are very similar to those of untreated larval populations. Consequently, residual populations do not necessarily warrant special consideration for the purpose of sea lamprey control and can be ranked for treatment along with other populations. Consecutive lampricide treatments, which are under evaluation by the sea lamprey control program, would bemost effective for reducing juvenile production in large, fast-growing populations.

The Effects of the Impedance of the Flow Source on the Design of Tidal Stream Generators

NASA Astrophysics Data System (ADS)

Salter, S.

2011-12-01

The maximum performance of a wind turbine is set by the well-known Betz limit. If the designer of a wind turbine uses too fast a rotation, too large a blade chord or too high an angle of blade pitch, the air flow can take an easier path over or around the rotor. Most estimates of the tidal stream resource use equations borrowed from wind and would be reasonably accurate for a single unit. But water cannot flow through the seabed or over rotors which reach to the surface. If contra-rotating, vertical-axis turbines with a rectangular flow-window are placed close to one another and reach from the surface close to the seabed, the leakage path is blocked and they become more like turbines in a closed duct. Instead of an equation with area times velocity-cubed we should use the first power of volume flow rate though the rotor times the pressure difference across it. A long channel with a rough bed will already be losing lots of energy and will behave more like a high impedance flow. Attempts to block it with closely-packed turbines will increase the head across the turbines with only a small effect on flow rate. The same thing will occur if a close-packed line of turbines is built out to sea from a headland. It is necessary to understand the impedance of the flow source all the way out to mid-ocean. In deep seas where the current velocities at the seabed are too slow to disturb the ooze the friction coefficients will be similar to those of gloss paint, perhaps 0.0025. But the higher velocities in shallow water will remove ooze and quite large sediments leaving rough, bare rock and leading to higher friction-coefficients. Energy dissipation will be set by the higher friction coefficients and the cube of the higher velocities. The presence of turbines will reduce seabed losses and about one third of the present loss can be converted to electricity. The velocity reduction would be about 10%. In many sites the energy output will be far higher than the wind turbine equations would predict. It may be possible to measure friction coefficients by looking at the slope of the water across a likely tidal stream site as indicated by the pressure-sensing instruments built in to acoustic Doppler current profilers. If this reasoning is correct it would lead to large changes in turbine design for tidal streams particularly with regard to the very large forces which have to be passed into the seabed. The spacing of three rotor diameters, often recommended for tidal stream turbines becomes the equivalent of leaking pipes in conventional hydro-electric plant. These design changes will be discussed. Reference Salter SH. Correcting the Under-estimate of the Tidal-Stream Resource of the Pentland Firth. 8th European Wave and Tidal Energy Conference, Uppsala 2009 From www.see.ed.ac.uk/~shs then browse to /Tidal stream.

Simulations of the Greenland ice sheet 100 years into the future with the full Stokes model Elmer/Ice

NASA Astrophysics Data System (ADS)

Seddik, H.; Greve, R.; Zwinger, T.; Gillet-Chaulet, F.; Gagliardini, O.

2011-12-01

The full Stokes thermo-mechanically coupled model Elmer/Ice is applied to the Greenland ice sheet. Elmer/Ice employs the finite element method to solve the full Stokes equations, the temperature evolution equation and the evolution equation of the free surface. The general framework of this modeling effort is a contribution to the Sea-level Response to Ice Sheet Evolution (SeaRISE) assessment project, a community-organized effort to estimate the likely range of ice sheet contributions to sea level rise over the next few hundred years (http://tinyurl.com/srise-lanl, http://tinyurl.com/srise-umt). The present geometry (surface and basal topographies) is derived from data where the basal topography was created with the preservation of the troughs at the Jakobshavn Ice Stream, Helheim, Kangerdlussuaq and Petermann glaciers. A mesh of the computational domain is created using an initial footprint which contains elements of 5 km horizontal resolution and to limit the number elements on the footprint while maximizing the spatial resolution, an anisotropic mesh adaptation scheme is employed based on the Hessian matrix of the observed surface velocities. The adaptation is carried out with the tool YAMS and the final footprint is vertically extruded to form a 3D mesh of 320880 elements with 17 equidistant, terrain-following layers. The numerical solution of the Stokes and the heat transfer equations employs direct solvers with stabilization procedures. The boundary conditions are such that the temperature at the surface uses the present-day mean annual air temperature given by a parameterization or directly from the available data, the geothermal heat flux at the bedrock is given by data and the lateral sides are open boundaries. A non-linear Weertman law is used for the basal sliding. Results for the SeaRISE 2011 sensitivity experiments are presented so that six different experiments have been conducted, grouped in two sets. The Set C (three experiments) applies a change to the surface precipitation and temperature and the set S (three experiments) applies an amplification factor to change the basal sliding velocity. The experiments are compared to a constant climate control run beginning at present (epoch 2004-1-1 0:0:0) and running up to 100 years holding the climate constant to its present state. The experiments with the amplification factor (Set S) show high sensitivities. Relative to the control run, the scenario with an amplification factor of 3x applied to the sliding velocity produces a Greenland contribution to sea level rise of ~25 cm. An amplification factor of 2.5x produces a contribution of ~16 cm and an amplification factor 2x produces a contribution of ~9 cm. The experiments with the changes to the surface precipitation and temperature (set C) show a contribution to sea level rise of ~4 cm when a factor 1x is applied to the temperature and precipitation anomalies. A factor 1.5x produces a sea level rise of ~8 cm and a factor 2x produces a sea level rise of ~12 cm.

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

Bougamont, M.; Christoffersen, P.; Price, S. F.

Ongoing, centennial-scale flow variability within the Ross ice streams of West Antarctica suggests that the present-day positive mass balance in this region may reverse in the future. Here we use a three-dimensional ice sheet model to simulate ice flow in this region over 250 years. The flow responds to changing basal properties, as a subglacial till layer interacts with water transported in an active subglacial hydrological system. We show that a persistent weak bed beneath the tributaries of the dormant Kamb Ice Stream is a source of internal ice flow instability, which reorganizes all ice streams in this region, leadingmore » to a reduced (positive) mass balance within decades and a net loss of ice within two centuries. This hitherto unaccounted for flow variability could raise sea level by 5 mm this century. Furthermore, better constraints on future sea level change from this region will require improved estimates of geothermal heat flux and subglacial water transport.« less

Northern North Atlantic Sea Surface Height and Ocean Heat Content Variability

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Rhines, Peter; Worthen, Denise L.

2013-01-01

The evolution of nearly 20 years of altimetric sea surface height (SSH) is investigated to understand its association with decadal to multidecadal variability of the North Atlantic heat content. Altimetric SSH is dominated by an increase of about 14 cm in the Labrador and Irminger seas from 1993 to 2011, while the opposite has occurred over the Gulf Stream region over the same time period. During the altimeter period the observed 0-700 m ocean heat content (OHC) in the subpolar gyre mirrors the increased SSH by its dominantly positive trend. Over a longer period, 1955-2011, fluctuations in the subpolar OHC reflect Atlantic multidecadal variability (AMV) and can be attributed to advection driven by the wind stress ''gyre mode'' bringing more subtropical waters into the subpolar gyre. The extended subpolar warming evident in SSH and OHC during the altimeter period represents transition of the AMV from cold to warm phase. In addition to the dominant trend, the first empirical orthogonal function SSH time series shows an abrupt change 2009-2010 reaching a new minimum in 2010. The change coincides with the change in the meridional overturning circulation at 26.5N as observed by the RAPID (Rapid Climate Change) project, and with extreme behavior of the wind stress gyre mode and of atmospheric blocking. While the general relationship between northern warming and Atlantic meridional overturning circulation (AMOC) volume transport remains undetermined, the meridional heat and salt transport carried by AMOC's arteries are rich with decade-to-century timescale variability.

Decadal Shift in West China Autumn Precipitation and its Association With Sea Surface Temperature

NASA Astrophysics Data System (ADS)

Wei, Ting; He, Shengping; Yan, Qing; Dong, Wenjie; Wen, Xiaohang

2018-01-01

West China autumn precipitation (WCAP) is the final stage of the rainy season in mainland China and is characterized as the secondary peak in annual cycle of precipitation in West China. This study reveals that WCAP experienced a significant interdecadal shift around the mid-1980s, with greatly reduced precipitation after this shift. Features related to the decrease in WCAP include the weakening of warm, wet southerlies prevailing from the oceans to inland China, the weakened Eurasian pattern, and the southward displacement of the East Asian jet stream (EAJS). Further analysis indicates that the interdecadal changes in WCAP may be attributed to the interdecadal increasing of sea surface temperature (SST) in the Indo-Pacific warm pool (SSTIOP), North Pacific (SSTNP), and central equatorial Pacific (SSTCEP) after the 1980s. The warmer SSTIOP contributes to a weaker meridional land-sea thermal contrast, which inducts an anomalous local meridional circulation and northerly. The warmer SSTNP stimulates a Rossby wave train that leads to weakened West Pacific subtropical high and accompanying cyclonic circulation anomaly, hindering the transport of water vapor inland from the oceans. The increased SSTCEP leads to the southward displacement of the EAJS and its secondary circulation, generating an anomalous descending branch and reduced WCAP. Numerical simulations further support the conclusions derived from the diagnostic analysis that the decadal warming of the SSTIOP, SSTNP, and SSTCEP synergistically contributes to the reduction of WCAP after the 1980s.

TOPEX/El Nino Watch - Satellite Shows Pacific Running Hot and Cold, September 12, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on September 12, 1998; these sea surface heights are an indicator of the changing amount of heat stored in the ocean. The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Nino, and a possibly waning La Nina situation. This image shows that the rapid cooling of the central tropical Pacific has slowed and this area of low sea level (shown in purple) has decreased slightly since last month. It is still uncertain, scientists say, that this cold pool will evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering to the north and south of the equator. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition. These strong patterns have remained in the climate system for many months and will continue to influence weather conditions around the world in the coming fall and winter. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. The purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. The white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. A La Nina situation is essentially the opposite of an El Nino condition, but during La Nina the trade winds are stronger than normal and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. A La Nina situation also changes global weather patterns, and is associated with less moisture in the air resulting in less rain along the west coasts of North and South America.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

A difficult Arctic science issue: Midlatitude weather linkages

NASA Astrophysics Data System (ADS)

Overland, James E.

2016-09-01

There is at present unresolved uncertainty whether Arctic amplification (increased air temperatures and loss of sea ice) impacts the location and intensities of recent major weather events in midlatitudes. There are three major impediments. The first is the null hypothesis where the shortness of time series since major amplification (∼15 years) is dominated by the variance of the physical process in the attribution calculation. This makes it impossible to robustly distinguish the influence of Arctic forcing of regional circulation from random events. The second is the large chaotic jet stream variability at midlatitudes producing a small Arctic forcing signal-to-noise ratio. Third, there are other potential external forcings of hemispheric circulation, such as teleconnections driven by tropical and midlatitude sea surface temperature anomalies. It is, however, important to note and understand recent emerging case studies. There is evidence for a causal connection of Barents-Kara sea ice loss, a stronger Siberian High, and cold air outbreaks into eastern Asia. Recent cold air penetrating into the southeastern United States was related to a shift in the long-wave atmospheric wind pattern and reinforced by warmer temperatures west of Greenland. Arctic Linkages is a major research challenge that benefits from an international focus on the topic.

E-Theatre

NASA Technical Reports Server (NTRS)

Hasler, Arthur F.; Einaudi, Franco (Technical Monitor)

2001-01-01

Mesoscale/severe storms and results from Terra Fritz Hasler (NASA/Goddard) will show the latest spectacular animations of the hurricanes and tropical storms: Floyd, Georges, Mitch, Bonnie etc. from Geostationary Operational Environmental Satellites (GOES) and Tropical Rain Measuring Mission (TRMM) supported by MMS 3D nested numerical model results. See dust storms in Africa and smoke plumes from fires in Mexico. See how High-Definition Television (HDTV) is revolutionizing entertainment and the way we communicate scientific results. Fly in from space and take a tour of Africa. Drop in on Albuquerque using 1-m Ikonos 'Spy Satellite' technology. See data from the new Earth Observing System (EOS) Terra satellite as well as Landsat 7, and SeaWiFS. See climate change in action with Global Land and Ocean productivity changes over the last 20 years. Remote sensing observations of Sea Surface Temperature (SST), El Nino, height, winds and ocean color from GOES, National Oceanic and Atmosphere Administration Advanced Very High Resolution Radiometer (AVHRR), Special Sensor Microwave Imager (SSMI), and SeaWiFS put in context with ten year LANL global ocean model. Compare the Gulf Stream observed by Terra with the simulations. Additional information is contained in the original extended abstract.

An Autonomous, Low Cost Platform for Seafloor Geodetic Observations

NASA Astrophysics Data System (ADS)

Ericksen, T.; Foster, J. H.; Bingham, B. S.; Oshiro, J.

2014-12-01

The Pacific GPS Facility and the Field Robotics Laboratory at the University of Hawaii have developed an approach to significantly reduce costs below ship based methods of accurately measuring short-term vertical motions of the seafloor and maintaining a continuous long-term record of seafloor pressure. Our goal has been to reduce the primary barrier preventing us from acquiring the observations we need to understand geodetic processes, and the hazards they present, at subduction zones, submarine volcanoes, and subsea landslides. To this end, we have designed a payload package for one of the University of Hawaii Wave Gliders which incorporates an acoustic telemetry package, a dual frequency geodetic-grade Global Positioning System (GPS) receiver, meteorological sensors, processing computer, and cellular communications. The Wave Glider will interrogate high accuracy pressure sensors on the seafloor to maintain a near-continuous stream of pressure and temperature data. The seafloor geodetic monument seats a sensor capable of recording pressure, temperature, and sound velocity for a deployment duration of over 5 years with an acoustic modem for communications, and an integral acoustic release for recovery and replacement of batteries. The design of the geodetic monument allows for precise repositioning of the sensor to extend the pressure record beyond a single 5+ year deployment, and includes the capability to install a mobile pressure recorder for calibration of the linear drift of the continuous pressure sensor. We will present the design of the Wave Glider payload and seafloor geodetic monument, as well as a discussion of nearshore and offshore field tests and operational procedures. An assessment of our ability to determine cm-scale vertical seafloor motions will be made by integrating the seafloor pressure measurements recovered during field testing with independent measurements of sea surface pressure and sea surface height made by the sea surface payload.

Compensatory mechanisms in Great Lakes sea lamprey populations: implications for alternative control strategies

USGS Publications Warehouse

Jones, Michael L.; Bergstedt, R.A.; Twohey, Michael B.; Fodale, Michael F.; Cuddy, Douglas W.; Slade, Jeffrey W.

2003-01-01

Compensatory mechanisms are demographic processes that tend to increase population growth rates at lower population density. These processes will tend to reduce the effectiveness of actions that use controls on reproductive success to suppress sea lamprey (Petromyzon marinus), an economically important pest in the Great Lakes. Historical evidence for compensatory mechanisms in sea lamprey populations was reviewed, and revealed: (1) strong evidence for shifts in sex ratios as sea lamprey abundance was reduced in the early years of the control program; (2) weak and equivocal evidence for increased growth rates of sea lamprey cohorts re-colonizing streams following a lampricide treatment; and (3) suggestions of other compensatory processes, such as earlier ages at metamorphosis, but with little empirical evidence. Larval size distribution data for cohorts in the first and second years following a lampricide treatment (26 pairs of cohorts in 20 streams) was analyzed and did not indicate a consistent pattern of more rapid growth of the first colonizing cohort (only 11 of 33 cases). To test for compensation between spawning and age-1 in sea lamprey populations, data were analyzed for 49 stream-years for which spawning female abundance was known and age-1 abundance was estimated in the following year. A fit of these data to a Ricker stock-recruitment function showed evidence for compensation, measured as reduced survival to age 1 at higher abundance of spawning females. More obvious, however, was a large amount of density-independent variation in survival, which tends to mask evidence for compensatory survival. The results were applied to a simple model that simulates sea lamprey populations and their control in a hypothetical lake. Control strategies that targeted reproductive success performed far less well than comparable strategies that targeted larval populations, because density-independent recruitment variation leads to occasional strong year classes even when spawner abundance is reduced to low levels through alternative control. It is concluded that further study of recruitment variation in lamprey populations is critical to rationalizing alternative controls that target reproductive success, and that recruitment variation needs to be incorporated into models used to evaluate sea lamprey control options.

TOPEX/El Nino Watch - October 3, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 3, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool in tropical Pacific resulting from El Nino seems to have stabilized. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 and 30 C (70 to 85 F), carries the amount of heat equal to 100 times the amount of fossil fuel energy consumed by the entire U.S. population during one year. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory indicating the presence of a strong El Nino condition throughout the coming winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Analysis of Ultra High Resolution Sea Surface Temperature Level 4 Datasets

NASA Technical Reports Server (NTRS)

Wagner, Grant

2011-01-01

Sea surface temperature (SST) studies are often focused on improving accuracy, or understanding and quantifying uncertainties in the measurement, as SST is a leading indicator of climate change and represents the longest time series of any ocean variable observed from space. Over the past several decades SST has been studied with the use of satellite data. This allows a larger area to be studied with much more frequent measurements being taken than direct measurements collected aboard ship or buoys. The Group for High Resolution Sea Surface Temperature (GHRSST) is an international project that distributes satellite derived sea surface temperatures (SST) data from multiple platforms and sensors. The goal of the project is to distribute these SSTs for operational uses such as ocean model assimilation and decision support applications, as well as support fundamental SST research and climate studies. Examples of near real time applications include hurricane and fisheries studies and numerical weather forecasting. The JPL group has produced a new 1 km daily global Level 4 SST product, the Multiscale Ultrahigh Resolution (MUR), that blends SST data from 3 distinct NASA radiometers: the Moderate Resolution Imaging Spectroradiometer (MODIS), the Advanced Very High Resolution Radiometer (AVHRR), and the Advanced Microwave Scanning Radiometer ? Earth Observing System(AMSRE). This new product requires further validation and accuracy assessment, especially in coastal regions.We examined the accuracy of the new MUR SST product by comparing the high resolution version and a lower resolution version that has been smoothed to 19 km (but still gridded to 1 km). Both versions were compared to the same data set of in situ buoy temperature measurements with a focus on study regions of the oceans surrounding North and Central America as well as two smaller regions around the Gulf Stream and California coast. Ocean fronts exhibit high temperature gradients (Roden, 1976), and thus satellite data of SST can be used in the detection of these fronts. In this case, accuracy is less of a concern because the primary focus is on the spatial derivative of SST. We calculated the gradients for both versions of the MUR data set and did statistical comparisons focusing on the same regions.

Linkages Between the Great Arctic Cyclone of August 2012 and Tropopause Polar Vortices

NASA Astrophysics Data System (ADS)

Biernat, K.; Keyser, D.; Bosart, L. F.

2017-12-01

Coherent vortices in the vicinity of the tropopause, referred to as tropopause polar vortices (TPVs), are common features in the Arctic. TPVs may interact with and strengthen jet streams, as well as act as precursor disturbances for the development of Arctic cyclones. Arctic cyclones may be associated with strong surface winds and poleward advection of warm, moist air, contributing to reductions in Arctic sea-ice extent. Also, heavy precipitation, strong surface winds, and large waves accompanying Arctic cyclones may pose hazards to ships moving through open passageways in the Arctic Ocean. The Great Arctic Cyclone of August 2012 (hereafter AC12) is an example of an intense Arctic cyclone. AC12 formed on 2 August 2012 over central Siberia and attained a minimum sea level pressure (SLP) of 964 hPa on 6 August 2012 over the Arctic. Strong surface winds associated with AC12 led to reductions in Arctic sea-ice extent during a time in which sea ice was thin. Two TPVs are hypothesized to play a role in the life cycle of AC12. The purpose of this study is to investigate the linkages between AC12 and the two TPVs. The ERA-Interim dataset was utilized to examine the linkages between AC12 and the two TPVs. The two TPVs, TPV 1 and TPV 2, were tracked objectively using a TPV tracking algorithm. AC12 was tracked manually by following the locations of minimum SLP. During early August 2012, as TPV 1 approached and interacted with AC12 in a region of strong baroclinicity, it likely played an important role in the subsequent intensification of AC12. In addition, TPV-jet interactions involving both TPV 1 and TPV 2 likely contributed to the formation of a dual-jet configuration and jet coupling over AC12. The presence of warm, moist air and relatively strong lower-tropospheric ascent in the region of jet coupling and the subsequent interaction between both TPVs likely facilitated the intensification of AC12. After attaining its minimum SLP, AC12 moved slowly over the Arctic, where its expansive surface wind field contributed to reductions of Arctic sea-ice extent over a prolonged period. This study illustrates that TPVs, along with associated TPV-jet and TPV-TPV interactions, may play important roles in the life cycles of Arctic cyclones, which may lead to reductions in Arctic sea-ice extent.

Late Holocene activity of the Dead Sea Transform revealed in 3D palaeoseismic trenches on the Jordan Gorge segment [rapid communication

NASA Astrophysics Data System (ADS)

Marco, Shmuel; Rockwell, Thomas K.; Heimann, Ariel; Frieslander, Uri; Agnon, Amotz

2005-05-01

Three-dimensional excavations of buried stream channels that have been displaced by the Jordan Fault, the primary strand of the Dead Sea fault zone in northern Israel, demonstrate that late Holocene slip has been primarily strike-slip at a minimum rate of 3 mm/yr. The palaeoseismic study was carried out in the Bet-Zayda Valley, the delta of the Jordan River at the north shore of the Sea of Galilee. The site was chosen where a north-striking scarp with up to 1-m vertical expression crosses the flat valley. One group of trench excavations was located where a small stream crosses the scarp. The active stream, which is incised into the scarp, is not offset by the fault. However we found two palaeo channels about 2 m below the surface offset sinistrally 2.7±0.2 m by the fault and two younger nested channels offset 0.5±0.05 m. Based on radiocarbon dates we attribute the last 0.5 m rupture to the earthquake of October 30, 1759. The older offset of 2.2 m most probably occurred in the earthquakes of May 20, 1202. These two events correlate with the findings at Ateret, about 12 km north of Bet-Zayda, where the 1202 earthquake produced 1.6 m of lateral displacement in E-W-striking defence walls of a Crusader castle, and an Ottoman mosque was offset 0.5 m in the earthquake of 1759. In the second group of trenches some 60 m farther south we found another offset channel. Its northern margin is displaced 15 m sinistrally whereas the southern margin shows only 9 m of sinistral offset. The dip slip component is 1.2 m, west side down. The different amounts of margin offset can be explained by erosion of the southern margin during the first 6 m of displacement. Additional slip of 9 m accrued after the stream had been abandoned and buried by a 2-m-thick lacustrine clay layers. Radiocarbon dates on organic residue provide the age control which indicates that the 15 m of slip has accrued over the past 5 kyr, yielding a short-term slip rate of 3 mm/yr for the late Holocene. It is possible that our study covers only part of the fault zone, hence we regard this mean slip rate to be a minimum for the DST. Based on other palaeoseismic studies the best estimate for Quaternary slip rate is 4±1 mm/yr.

The Orinoco megadelta as a conservation target in the face of the ongoing and future sea level rise.

PubMed

Vegas-Vilarrúbia, T; Hernández, E; Rull, Valentí; Rull Vegas, Elisa

2015-05-15

Currently, risk assessments related to rising sea levels and the adoption of defensive or adaptive measures to counter these sea level increases are underway for densely populated deltas where economic losses might be important, especially in the developed world. However, many underpopulated deltas harbouring high biological and cultural diversity are also at risk but will most likely continue to be ignored as conservation targets. In this study, we explore the potential effects of erosion, inundation and salinisation on one of the world's comparatively underpopulated megadeltas, the Orinoco Delta. With a 1 m sea level rise expected to occur by 2100, several models predict a moderate erosion of the delta's shorelines, migration or loss of mangroves, general inundation of the delta with an accompanying submersion of wetlands, and an increase in the distance to which sea water intrudes into streams, resulting in harm to the freshwater biota and resources. The Warao people are the indigenous inhabitants of the Orinoco Delta and currently are subject to various socioeconomic stressors. Changes due to sea level rise will occur extremely rapidly and cause abrupt shifts in the Warao's traditional environments and resources, resulting in migrations and abandonment of their ancestral territories. However, evidence indicates that deltaic aggradation/accretion processes at the Orinoco delta due to allochthonous sediment input and vegetation growth could be elevating the surface of the land, keeping pace with the local sea level rise. Other underpopulated and large deltas of the world also may risk immeasurable biodiversity and cultural losses and should not be forgotten as important conservation targets. Copyright © 2015. Published by Elsevier B.V.

Cultivation mutualism between a deep-sea vent galatheid crab and its chemosynthetic epibionts

NASA Astrophysics Data System (ADS)

Watsuji, Tomo-o.; Tsubaki, Remi; Chen, Chong; Nagai, Yukiko; Nakagawa, Satoshi; Yamamoto, Masahiro; Nishiura, Daisuke; Toyofuku, Takashi; Takai, Ken

2017-09-01

Since the discovery of deep-sea hydrothermal vents in 1977, chemosynthesis-based ecosystems have been found in a wide range of habitats, such as hydrocarbon seeps, coastal sediments and terrestrial caves. Several invertebrates found in dark ecosystems harbor chemosynthetic bacteria (epibionts) on the surfaces of their specialised tissues; in particular, a vent galatheid crab Shinkaia crosnieri consumes the epibionts thriving on their setae as the primary nutritional source. In this study, we found that the water stream is the key to the nutritional symbiosis between S. crosnieri and chemosynthetic epibionts. The chemosynthetic functions of epibionts were highly activated by the water flow, and observations in the laboratory supported rheotaxis by S. crosnieri. In addition, endogenous water flow generated by respiratory water ventilation of S. crosnieri stimulated the chemosynthetic activity of epibionts under static conditions. These results point out that the epibionts are cultivated by the active behaviors of S. crosnieri, potentially representing the first example of a cultivation mutualism in chemosynthetic ectosymbiosis.

Using U-Pb Detrital Zircon Geochronology to Study Ice Streams in the Weddell Sea Embayment, Antarctica

NASA Astrophysics Data System (ADS)

Agrios, L.; Licht, K.; Hemming, S. R.; Williams, T.

2016-12-01

Till from major ice streams of the Weddell Sea Embayment contain detrital zircons with distinct U-Pb age populations that can be used as a provenance tool to better understand ice stream dynamics. The ice streams in this study include the Foundation Ice Stream, and Academy, Slessor, and Recovery glaciers, all of which drain ice from the continent's interior into the Weddell Sea. Characterizing the U-Pb detrital zircon ages in till and rocks will (1) provide the zircon provenance signatures of the material carried by the ice stream - when these signatures are found in LGM and older deposits downstream they can enable interpretation of past ice flow history; and (2) constrain ice-covered upstream bedrock geology that supplies the till carried by ice streams and glaciers. U-Pb ages of detrital zircons were measured in 21 samples of onshore till, erratics, and bedrock of potential source rocks. Grains were analyzed by LA-ICPMS at the University of Arizona (n=300). Relative probability U-Pb age density plots of till in moraines along the Foundation Ice Stream and Academy Glacier show prominent peaks at 500-530 and 615-650 Ma, which overlap with the timing of the Ross and Pan-African orogenies. Zircon ages of 1000-1095 Ma are also present. Local bedrock in the Patuxent Range has the most prominent peak at 510 Ma, suggesting the till is predominantly derived from local Patuxent Formation. However, local bedrock also has fewer grains at 1030 Ma which suggests that this age population is carried in the till as well. Prominent peaks in U-Pb ages from till transported by the Recovery Glacier are 530, 635, 1610 and 1770 Ma. Bedrock of this area contains similar age peaks, with the exception of the 635 Ma peak, suggesting that this ice stream is carrying a signature from an unexposed source of this age completely buried by ice. The Slessor Glacier carries zircons with prominent populations at 1710 and 2260-2420 Ma, which overlap with a high-grade metamorphic event in the Shackleton Range between 1710-1680 Ma. In order to gain the offshore signature of ice streams, these data will be compared to 40Ar/39Ar hornblende and biotite thermochronological data, and U-Pb geochronology data from subglacial till and proximal glaciomarine sediment from existing core sites located at the edge of the Ronne-Filchner Ice Shelf.

Characterization of Archaeal Community in Contaminated and Uncontaminated Surface Stream Sediments

PubMed Central

Porat, Iris; Vishnivetskaya, Tatiana A.; Mosher, Jennifer J.; Brandt, Craig C.; Yang, Zamin K.; Brooks, Scott C.; Liang, Liyuan; Drake, Meghan M.; Podar, Mircea; Brown, Steven D.

2010-01-01

Archaeal communities from mercury and uranium-contaminated freshwater stream sediments were characterized and compared to archaeal communities present in an uncontaminated stream located in the vicinity of Oak Ridge, TN, USA. The distribution of the Archaea was determined by pyrosequencing analysis of the V4 region of 16S rRNA amplified from 12 streambed surface sediments. Crenarchaeota comprised 76% of the 1,670 archaeal sequences and the remaining 24% were from Euryarchaeota. Phylogenetic analysis further classified the Crenarchaeota as a Freshwater Group, Miscellaneous Crenarchaeota group, Group I3, Rice Cluster VI and IV, Marine Group I and Marine Benthic Group B; and the Euryarchaeota into Methanomicrobiales, Methanosarcinales, Methanobacteriales, Rice Cluster III, Marine Benthic Group D, Deep Sea Hydrothermal Vent Euryarchaeota 1 and Eury 5. All groups were previously described. Both hydrogen- and acetate-dependent methanogens were found in all samples. Most of the groups (with 60% of the sequences) described in this study were not similar to any cultivated isolates, making it difficult to discern their function in the freshwater microbial community. A significant decrease in the number of sequences, as well as in the diversity of archaeal communities was found in the contaminated sites. The Marine Group I, including the ammonia oxidizer Nitrosopumilus maritimus, was the dominant group in both mercury and uranium/nitrate-contaminated sites. The uranium-contaminated site also contained a high concentration of nitrate, thus Marine Group I may play a role in nitrogen cycle. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9734-2) contains supplementary material, which is available to authorized users. PMID:20725722

The influence of data characteristics on detecting wetland/stream surface-water connections in the Delmarva Peninsula, Maryland and Delaware

USGS Publications Warehouse

Vanderhoof, Melanie; Distler, Hayley; Lang, Megan W.; Alexander, Laurie C.

2018-01-01

The dependence of downstream waters on upstream ecosystems necessitates an improved understanding of watershed-scale hydrological interactions including connections between wetlands and streams. An evaluation of such connections is challenging when, (1) accurate and complete datasets of wetland and stream locations are often not available and (2) natural variability in surface-water extent influences the frequency and duration of wetland/stream connectivity. The Upper Choptank River watershed on the Delmarva Peninsula in eastern Maryland and Delaware is dominated by a high density of small, forested wetlands. In this analysis, wetland/stream surface water connections were quantified using multiple wetland and stream datasets, including headwater streams and depressions mapped from a lidar-derived digital elevation model. Surface-water extent was mapped across the watershed for spring 2015 using Landsat-8, Radarsat-2 and Worldview-3 imagery. The frequency of wetland/stream connections increased as a more complete and accurate stream dataset was used and surface-water extent was included, in particular when the spatial resolution of the imagery was finer (i.e., <10 m). Depending on the datasets used, 12–60% of wetlands by count (21–93% of wetlands by area) experienced surface-water interactions with streams during spring 2015. This translated into a range of 50–94% of the watershed contributing direct surface water runoff to streamflow. This finding suggests that our interpretation of the frequency and duration of wetland/stream connections will be influenced not only by the spatial and temporal characteristics of wetlands, streams and potential flowpaths, but also by the completeness, accuracy and resolution of input datasets.

TOPEX/El Nino Watch - October 23, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 23, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool associated with the El Nino has returned to the volume it was in mid-September after dropping to a temporary low at the beginning of October. The sea surface elevation just north of the El Nino warm pool continues to drop (purple area), enhancing the eastward flowing North Equatorial Counter Current. The intensification of this current is another tell-tale sign of the El Nino phenomenon. This flow contributes to the rise in sea level along the western coasts of the Americas that will progress towards both the north and south poles over the next several months. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70- 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

On the size and distribution of rings and coherent vortices in the Sargasso Sea

NASA Astrophysics Data System (ADS)

Luce, David L.; Rossby, Tom

2008-05-01

The container motor vessel CMV Oleander, which operates between New Jersey and Bermuda, crosses the Gulf Stream and Sargasso Sea all year round on a semiweekly schedule. Using an acoustic Doppler current profiler, measurements of upper ocean currents have been made on a regular basis since the fall of 1992. In this paper we examine the database for evidence of axisymmetric coherent vortices including the distribution and intensity of cold core rings. To detect the existence of coherent vortices, the patterns of current vectors averaged between 40 and 80 m depth were fit to an axisymmetric Gaussian vortex model. The parameters of the model were axis location, maximum tangential, or swirl, speed, and radius at which the maximum swirl was measured. We were able to distinguish between the well-known cold core "rings" (CCRs) pinched from the Gulf Stream, and a population of cyclonic and anticyclonic "vortices" in the Sargasso Sea. Both the rings and the Sargasso Sea vortices showed radii of 64 ± 18 km, albeit with different swirl speeds. The rings, close to the Gulf Stream, exhibited a typical maximum swirl speed of 0.98 ± 0.40 m s-1 and a center relative vorticity of 0.64 ± 0.35 × 10-4 s-1, almost 80% of the planetary vorticity for the region. The more uniform population of Sargasso Sea vortices contained approximately equal numbers of cyclones and anticyclones, with mean speeds of +0.43 and -0.55 m s-1, and center relative vorticities of +0.24 × 10-4 s-1 and -0.29 × 10-4 s-1, respectively.

Seasonal occurrence of sperm whales (Physeter macrocephalus) around Kelvin Seamount in the Sargasso Sea in relation to oceanographic processes

NASA Astrophysics Data System (ADS)

Wong, Sarah N. P.; Whitehead, Hal

2014-09-01

Sperm whales (Physeter macrocephalus) are widely distributed in all oceans, but they are clumped geographically, generally in areas associated with high primary and secondary productivity. The warm, clear waters of the Sargasso Sea are traditionally thought to be low in productivity, however recent surveys have found large numbers of sperm whales there. The New England Seamount Chain bisects the north-western portion of the Sargasso Sea, and might influence the mesoscale eddies associated with the Gulf Stream; creating areas of higher productivity within the Sargasso Sea. We investigated the seasonal occurrence of sperm whales over Kelvin Seamount (part of the New England Seamount Chain) and how it is influenced by oceanographic variables. An autonomous recording device was deployed over Kelvin Seamount from May to June 2006 and November 2006 to June 2007. A total of 6505 hourly two-minute recordings were examined for the presence of sperm whale echolocation clicks. Sperm whales were more prevalent around Kelvin in the spring (April to June: mean=51% of recordings contained clicks) compared to the winter (November to March: mean=16% of recordings contained clicks). Sperm whale prevalence at Kelvin was related to chlorophyll-a concentration four weeks previous, eddy kinetic energy and month. The mesoscale activity associated with the Gulf Stream and the Gulf Stream's interaction with the New England Seamount Chain likely play an important role in sperm whale occurrence in this area, by increasing productivity and perhaps concentration of cephalopod species.

A numerical investigation of surface-induced mesocyclogenesis near the Gulf Stream

NASA Astrophysics Data System (ADS)

Cione, Joseph J.; Raman, Sethu

1995-10-01

A series of numerical experiments designed to simulate the initial development stages of low-level coastal mesocyclogenesis near the Gulf Stream was recently conducted. Under initially quiescent conditions, surface cyclogenesis in the control simulation occurs along a Gulf Stream meander in a region where the gradients in sea surface temperature (SST) are maximized. A low-level mesovortex on the order of 140km forms approximately 12 h into the simulation and continues to intensify through 42h. During the 24 48 h time period, a mesoscale frontal feature develops in direct response to strong diabatic forcing associated with sustained surface latent and sensible heating near the Gulf Stream frontal zone south of the main circulation center. Due to the non-linear advection of the frontal feature during this time period, the previously quasi-stationary circulation center drifts eastward (and away) from the thermal forcing associated with the large SST gradients found to the west. This eastward frontal propagation acts to decrease the magnitude of the low level horizontal air temperature gradient near the center of circulation throughout the 24 42 h development period. During the 42 48-h period, the relatively quick moving frontal feature acts to severely shear the nearly stationary center of circulation in the east west direction. As a result, the mesoscale system begins to fill during the final 6 h of integration. In addition to the control simulation, additional sensitivity experiments were conducted. These experiments were specifically designed to: (1) investigate how the magnitude of the Gulf Stream SST gradients affect the timing and degree of cyclonic development; (2) address the impact surface moisture fluxes and moist convection each have on the simulated low level mesocyclogenesis; (3) isolate the role surface sensible heating plays in the overall development of the simulated mesocyclone. Results from the SST gradient experiment indicate that a moderate enhancement of the SST distribution significantly affects the timing of the initial cyclogenesis and the maximum intensity of the simulated frontal circulation. For the "no turbulent heat flux" experiment, it appears that the elimination of surface sensible heating does not radically alter the overall structure of the simulated mesocyclone. However, the rate of development during the early stage of cyclogenesis, the absolute peak intensity of the system as well as the vertical depth of the simulated mesoscale frontal feature were all noticeably reduced when compared with the control simulation. The initial development of a closed low level circulation was delayed by nearly 18 h in the absence surface latent heat fluxes. Once formed, the system intensified throughout the 48-h period of integration, but unlike the control experiment, a mesoscale frontal feature south of the main circulation center was not simulated. Results from the "no surface moisture flux/no moist convection" simulation illustrate that moist convective processes play a dominant role in the overall development of the mesoscale cyclone. For this particular case, a weak and extremely shallow circulation was simulated after 24h. This circulation quickly eroded however, and was virtually non-existent for integration times greater than 39h.

Understanding the Impact of Model Surfactants on Cloud Condensation Nuclei Activity of Sea Spray Aerosols

NASA Astrophysics Data System (ADS)

Forestieri, S.; Cappa, C. D.; Ruehl, C. R.; Bertram, T. H.; Staudt, S.; Kuborn, T.

2017-12-01

Aerosol impacts on cloud properties, also known as indirect effects, remain a major source of uncertainty in modeling global radiative forcing. Reducing this uncertainty necessitates better understanding of how aerosol chemical composition impacts the cloud-forming ability of aerosols. The presence of surfactants in aerosols can decrease the surface tension of activating droplets relative to water and lead to more efficient activation. The importance of this effect has been debated, but recent surface tension measurements of microscopic droplets indicate that surface tension is substantially depressed relative to water for lab-generated particles consisting of salt and a single organic species and for complex mixtures of organic matter. However, little work has been done on understanding how chemical complexity (i.e. interaction between different surfactant species) impacts surface tension for particles containing mixtures of surfactants. In this work, we quantified the surface tension of lab-generated aerosols containing surfactants that are commonly found in nascent sea spray aerosol (SSA) at humidities close to activation using a continuous flow stream-wise thermal gradient chamber (CFSTGC). Surface tension was quantified for particles containing single surfactant species and mixtures of these surfactants to investigate the role of chemical complexity on surface tension and molecular packing at the air-water interface. For all surfactants tested in this study, substantial surface tension depression (20-40 mN/m) relative to water was observed for particles containing large fractions of organic matter at humidities just below activation. However, the presence of these surfactants only weakly depressed surface tension at activation. Kinetic limitations were observed for particles coated with just palmitic acid, since palmitic acid molecules inhibit water uptake through their ability to pack tightly at the surface. However, these kinetic limitations disappeared when palmitic acid was mixed with oleic acid, indicating a disruption in packing. The impact of oxidation on droplet surface tension will also be discussed.

Tectonic and climatic significance of a late Eocene low-relief, high-level geomorphic surface, Colorado

NASA Technical Reports Server (NTRS)

Gregory, Kathryn M.; Chase, Clement G

1994-01-01

New paleobotanical data suggest that in the late Eocene the erosion surface which capped the Front Range, Colorado was 2.2-2.3 km in elevation, which is similar to the 2.5-km present elevation of surface remnants. This estimated elevation casts doubt on the conventional belief that the low-relief geomorphic surface was formed by lateral planation of streams to a base level not much higher than sea level and that the present deeply incised canyons must represent Neogene uplift of Colorado. Description of the surface, calculations of sediment volume, and isostatic balance and fluvial landsculpting models demonstrate that while the high elevation of the erosion surface was due to tectonic forces, its smoothness was mostly a result of climatic factors. A sediment balance calculated for the Front Range suggests that from 2 to 4 km of material were eroded by the late Eocene, consistent with fission track ages. This amount of erosion would remove a significant portionof the 7 km of Laramide upper crustal thickening. Isostatic modeling implies that the 2.2-3.3 km elevation was most likely created by lower crustal thickening during the Laramide. A numerical model of fluvial erosion and deposition suggests a way that a late Eocene surface could have formed at this high elevation without incision. A humid climate with a preponderance of small storm events will diffusively smooth topography and is a possible mechanism for formation oflow-relief, high-level surfaces. Paleoclimate models suggest a lack of large strom events in the late Eocene because of cool sea surface temperatures in the equatorial region. Return to a drier but stormier climate post-Eocene could have caused the incision of the surface by young canyons. By this interpretation, regional erosion surfaces may represent regional climatic rather than tectonic conditions.

Stream temperature variability: why it matters to salmon

Treesearch

E. Ashley Steel; Brian Beckman; Marie Oliver

2014-01-01

Salmon evolved in natural river systems, where temperatures fluctuate daily, weekly, seasonally, and all along a stream’s path—from the mountains to the sea. Climate change and human activities alter this natural variability. Dams, for example, tend to reduce thermal fluctuations.Currently, scientists gauge habitat suitability for aquatic species by...

Use of physiological knowledge to control the invasive sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes.

PubMed

Siefkes, Michael J

2017-01-01

Sea lamprey ( Petromyzon marinus ) control in the Laurentian Great Lakes of North America is an example of using physiological knowledge to successfully control an invasive species and rehabilitate an ecosystem and valuable fishery. The parasitic sea lamprey contributed to the devastating collapse of native fish communities after invading the Great Lakes during the 1800s and early 1900s. Economic tragedy ensued with the loss of the fishery and severe impacts to property values and tourism resulting from sea lamprey-induced ecological changes. To control the sea lamprey and rehabilitate the once vibrant Great Lakes ecosystem and economy, the Great Lakes Fishery Commission (Commission) was formed by treaty between Canada and the United States in 1955. The Commission has developed a sea lamprey control programme based on their physiological vulnerabilities, which includes (i) the application of selective pesticides (lampricides), which successfully kill sedentary sea lamprey larvae in their natal streams; (ii) barriers to spawning migrations and associated traps to prevent infestations of upstream habitats and remove adult sea lamprey before they reproduce; and (iii) the release of sterilized males to reduce the reproductive potential of spawning populations in select streams. Since 1958, the application of the sea lamprey control programme has suppressed sea lamprey populations by ~90% from peak abundance. Great Lakes fish populations have rebounded and the economy is now thriving. In hopes of further enhancing the efficacy and selectivity of the sea lamprey control programme, the Commission is exploring the use of (i) sea lamprey chemosensory cues (pheromones and alarm cues) to manipulate behaviours and physiologies, and (ii) genetics to identify and manipulate genes associated with key physiological functions, for control purposes. Overall, the Commission capitalizes on the unique physiology of the sea lamprey and strives to develop a diverse integrated programme to successfully control a once devastating invasive species.

Use of physiological knowledge to control the invasive sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes

PubMed Central

2017-01-01

Abstract Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America is an example of using physiological knowledge to successfully control an invasive species and rehabilitate an ecosystem and valuable fishery. The parasitic sea lamprey contributed to the devastating collapse of native fish communities after invading the Great Lakes during the 1800s and early 1900s. Economic tragedy ensued with the loss of the fishery and severe impacts to property values and tourism resulting from sea lamprey-induced ecological changes. To control the sea lamprey and rehabilitate the once vibrant Great Lakes ecosystem and economy, the Great Lakes Fishery Commission (Commission) was formed by treaty between Canada and the United States in 1955. The Commission has developed a sea lamprey control programme based on their physiological vulnerabilities, which includes (i) the application of selective pesticides (lampricides), which successfully kill sedentary sea lamprey larvae in their natal streams; (ii) barriers to spawning migrations and associated traps to prevent infestations of upstream habitats and remove adult sea lamprey before they reproduce; and (iii) the release of sterilized males to reduce the reproductive potential of spawning populations in select streams. Since 1958, the application of the sea lamprey control programme has suppressed sea lamprey populations by ~90% from peak abundance. Great Lakes fish populations have rebounded and the economy is now thriving. In hopes of further enhancing the efficacy and selectivity of the sea lamprey control programme, the Commission is exploring the use of (i) sea lamprey chemosensory cues (pheromones and alarm cues) to manipulate behaviours and physiologies, and (ii) genetics to identify and manipulate genes associated with key physiological functions, for control purposes. Overall, the Commission capitalizes on the unique physiology of the sea lamprey and strives to develop a diverse integrated programme to successfully control a once devastating invasive species. PMID:28580146

Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation.

PubMed

Stokes, C R; Margold, M; Clark, C D; Tarasov, L

2016-02-18

The contribution of the Greenland and West Antarctic ice sheets to sea level has increased in recent decades, largely owing to the thinning and retreat of outlet glaciers and ice streams. This dynamic loss is a serious concern, with some modelling studies suggesting that the collapse of a major ice sheet could be imminent or potentially underway in West Antarctica, but others predicting a more limited response. A major problem is that observations used to initialize and calibrate models typically span only a few decades, and, at the ice-sheet scale, it is unclear how the entire drainage network of ice streams evolves over longer timescales. This represents one of the largest sources of uncertainty when predicting the contributions of ice sheets to sea-level rise. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean-climate forcing. Here we reconstruct the activity of 117 ice streams that operated at various times during deglaciation of the Laurentide Ice Sheet (from about 22,000 to 7,000 years ago) and show that as they activated and deactivated in different locations, their overall number decreased, they occupied a progressively smaller percentage of the ice sheet perimeter and their total discharge decreased. The underlying geology and topography clearly influenced ice stream activity, but--at the ice-sheet scale--their drainage network adjusted and was linked to changes in ice sheet volume. It is unclear whether these findings can be directly translated to modern ice sheets. However, contrary to the view that sees ice streams as unstable entities that can accelerate ice-sheet deglaciation, we conclude that ice streams exerted progressively less influence on ice sheet mass balance during the retreat of the Laurentide Ice Sheet.

The Ocean-Atmosphere Hydrothermohaline Conveyor Belt

NASA Astrophysics Data System (ADS)

Döös, Kristofer; Kjellsson, Joakim; Zika, Jan; Laliberté, Frédéric; Brodeau, Laurent

2015-04-01

The ocean thermohaline circulation is linked to the hydrothermal circulation of the atmosphere. The ocean thermohaline circulation is expressed in potential temperature-salinity space and comprises a tropical upper-ocean circulation, a global conveyor belt cell and an Antarctic Bottom Water cell. The atmospheric hydrothermal circulation in a potential temperature-specific humidity space unifies the tropical Hadley and Walker cells as well as the midlatitude eddies into a single, global circulation. Superimposed, these thermohaline and hydrothermal stream functions reveal the possibility of a close connection between some parts of the water and air mass conversions. The exchange of heat and fresh water through the sea surface (precipiation-evaporation) and incoming solar radiation act to make near-surface air warm and moist while making surface water warmer and saltier as both air and water travel towards the Equator. In the tropics, air masses can undergo moist convection releasing latent heat by forming precipitation, thus acting to make warm surface water fresher. We propose that the Clausius-Clapeyron relationship for moist near-surface air acts like a lower bound for the atmospheric hydrothermal cell and an upper bound for the ocean thermohaline Conveyor-Belt cell. The analysis is made by combining and merging the overturning circulation of the ocean and atmosphere by relating the salinity of the ocean to the humidity of the atmosphere, where we set the heat and freshwater transports equal in the two stream functions By using simulations integrated with our Climate-Earth system model EC-Earth, we intend to produce the "hydrothermohaline" stream function of the coupled ocean-atmosphere overturning circulation in one single picture. We explore how the oceanic thermohaline Conveyor Belt can be linked to the global atmospheric hydrothermal circulation and if the water and air mass conversions in humidity-temperature-salinity space can be related and linked to each other along a "line" corresponding to the Clausius-Clapeyron relationship. A geographical description of how and where this occurs together with this new hydrothermohaline stream function will be searched for. The net heat and freshwater transport of the ocean and atmosphere can aslo be calculated from the thermohaline and hydrothermal stream functions. The heat transport across isohumes in the atmosphere and isohalines in the ocean as well as the freshwater transport across isotherms in both the atmosphere and ocean are computed. The maximum heat transport is about 16 PW in the atmosphere, while that of the ocean is just about 1 PW. The freshwater transport across isotherms in the atmosphere and ocean are shown to be tightly connected with a net maximum freshwater transport of 4 SV in the atmosphere and 2 Sv in the ocean.

Sea Surface Scanner: An advanced catamaran to study the sea surface

NASA Astrophysics Data System (ADS)

Wurl, O.; Mustaffa, N. I. H.; Ribas Ribas, M.

2016-02-01

The Sea Surface Scanner is a remote-controlled catamaran with the capability to sample the sea-surface microlayer in high resolution. The catamaran is equipped with a suite of sensors to scan the sea surface on chemical, biological and physical parameters. Parameters include UV absorption, fluorescence spectra, chlorophyll-a, photosynthetic efficiency, chromophoric dissolved organic matter (CDOM), dissolved oxygen, pH, temperature, and salinity. A further feature is a capability to collect remotely discrete water samples for detailed lab analysis. We present the first high-resolution (< 30 sec) data on the sea surface microlayer. We discuss the variability of biochemical properties of the sea surface and its implication on air-sea interaction.

Simulation of an oil film at the sea surface and its radiometric properties in the SWIR

NASA Astrophysics Data System (ADS)

Schwenger, Frédéric; Van Eijk, Alexander M. J.

2017-10-01

The knowledge of the optical contrast of an oil layer on the sea under various surface roughness conditions is of great interest for oil slick monitoring techniques. This paper presents a 3D simulation of a dynamic sea surface contaminated by a floating oil film. The simulation considers the damping influence of oil on the ocean waves and its physical properties. It calculates the radiance contrast of the sea surface polluted by the oil film in relation to a clean sea surface for the SWIR spectral band. Our computer simulation combines the 3D simulation of a maritime scene (open clear sea/clear sky) with an oil film at the sea surface. The basic geometry of a clean sea surface is modeled by a composition of smooth wind driven gravity waves. Oil on the sea surface attenuates the capillary and short gravity waves modulating the wave power density spectrum of these waves. The radiance of the maritime scene is calculated in the SWIR spectral band with the emitted sea surface radiance and the specularly reflected sky radiance as components. Wave hiding and shadowing, especially occurring at low viewing angles, are considered. The specular reflection of the sky radiance at the clean sea surface is modeled by an analytical statistical bidirectional reflectance distribution function (BRDF) of the sea surface. For oil at the sea surface, a specific BRDF is used influenced by the reduced surface roughness, i.e., the modulated wave density spectrum. The radiance contrast of an oil film in relation to the clean sea surface is calculated for different viewing angles, wind speeds, and oil types characterized by their specific physical properties.

Sodium and chloride levels in rainfall, mist. streamwater and groundwater at the Plynlimon catchments, mid-Wales: inferences on hydrological and chemical controls

NASA Astrophysics Data System (ADS)

Neal, C.; Kirchner, J. W.

Variations in sodium and chloride in atmospheric inputs (rainfall and mist), stream runoff and groundwater stores are documented for the upper Severn River (Afon Hafren and Afon Hore catchments), Plynlimon, mid-Wales. The results show five salient features.

1. Sodium and chloride concentrations are highly variable and highly correlated in rainfall and mist. The sodium-chloride relationship in rainfall has a slope close to the sodium/chloride ratio in sea-water, and an intercept that is not significantly different from zero. This indicates that sea-salt is the dominant source of both sodium and chloride in rainfall, which would be expected given the maritime nature of the metrology. For mist, there is also a straight line with near-zero intercept, but with a slightly higher gradient than the sea-salt ratio, presumably due to small additional sodium inputs from other sources.
2. There is an approximate input-output balance for both sodium and chloride, with the exception of one groundwater well, in which high chemical weathering results in an anomalous high Na/Cl ratio. Thus, atmospheric deposition is the dominant source of both sodium and chloride in groundwater and streamflow.
3. The fluctuations in sodium and chloride concentrations in the streams and groundwaters are strongly damped compared to those in the rain and the mist, reflecting the storage and mixing of waters in the subsurface.
4. On all timescales, from weeks to years, sodium fluctuations are more strongly damped than chloride fluctuations in streamflow. The additional damping of sodium is consistent with ion exchange buffering of sodium in the catchment soils.
5. Sodium and chloride concentrations are linearly correlated in the streams and groundwaters, but the slope is almost universally less than the sea-salt ratio and there is a non-zero intercept. The Na/Cl ratio in streamflow and groundwater is higher than the sea-salt ratio when salinity is low and lower than the sea-salt ratio when salinity is high. This pattern of behaviour is again consistent with ion exchange buffering of sodium in the catchment soils.

Topographyc metrics in the southern sector of the Marche foothills: implication for active tectonic analysis

NASA Astrophysics Data System (ADS)

Materazzi, Marco; Aringoli, Domenico; Carducci, Tamara; Cavitolo, Paolo; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

2016-04-01

Quantitative geomorphic analysis can be provided a useful contribution to the study of recent tectonics. Some parameters, that quantify the channels morphology, as the Stream Length-Gradient (SL) Index (Hack, 1973) and the Steepness (Ks) Index (Flint, 1974), are generally used to detect anomalies on the expected concave-up equilibrium stream-profile, which can result in local abrupt changes in stream gradient (i.e., knickpoints) and/or broad convexities on stream long-profiles extending for tens of kilometres (i.e., knickzones). The main goal of this work is the study of the morphological and morphometrical features in the southern sector of the Marche Region, with the aim to gain new knowledge on the influences of rock resistance and rock uplift on the fluvial and topographic system. The investigated area is situated in central Italy and it extends from the axial zone of the Umbria-Marche Apennines to the Adriatic Sea, including the southern sector of the Marche Region and belongs to the foredeep domain of the Apennines orogenic system, which has affected by tectonic activity up to very recent times. The rheology of outcropping deposits doesn't allow the strain to be easily recorded at the outcrop scale. The analyses have been aimed at to test the sensitivity of both SL and Ks for evaluating active crustal deformations, acting at different wavelengths on land surface, within a low tectonically active thrust-and-fold belt. Additional purpose was the understanding of the pattern of regional differential crustal activity in the topographic arrangement of the study area In this research project two sets of analysis were conducted. References Hack J.T. 1973. Stream-profile analysis and stream-gradient index. Journal of Research of the U.S. Geological Survey, 1, 421-429. Flint J.J. 1974. Stream gradient as a function of order, magnitude and discharge. Water Resources Research, 10, 969-973.

Estimating parasitic sea lamprey abundance in Lake Huron from heterogenous data sources

USGS Publications Warehouse

Young, Robert J.; Jones, Michael L.; Bence, James R.; McDonald, Rodney B.; Mullett, Katherine M.; Bergstedt, Roger A.

2003-01-01

The Great Lakes Fishery Commission uses time series of transformer, parasitic, and spawning population estimates to evaluate the effectiveness of its sea lamprey (Petromyzon marinus) control program. This study used an inverse variance weighting method to integrate Lake Huron sea lamprey population estimates derived from two estimation procedures: 1) prediction of the lake-wide spawning population from a regression model based on stream size and, 2) whole-lake mark and recapture estimates. In addition, we used a re-sampling procedure to evaluate the effect of trading off sampling effort between the regression and mark-recapture models. Population estimates derived from the regression model ranged from 132,000 to 377,000 while mark-recapture estimates of marked recently metamorphosed juveniles and parasitic sea lampreys ranged from 536,000 to 634,000 and 484,000 to 1,608,000, respectively. The precision of the estimates varied greatly among estimation procedures and years. The integrated estimate of the mark-recapture and spawner regression procedures ranged from 252,000 to 702,000 transformers. The re-sampling procedure indicated that the regression model is more sensitive to reduction in sampling effort than the mark-recapture model. Reliance on either the regression or mark-recapture model alone could produce misleading estimates of abundance of sea lampreys and the effect of the control program on sea lamprey abundance. These analyses indicate that the precision of the lakewide population estimate can be maximized by re-allocating sampling effort from marking sea lampreys to trapping additional streams.

Depositional controls on coal distribution and quality in the Eocene Brunner Coal Measures, Buller Coalfield, South Island, New Zealand

USGS Publications Warehouse

Flores, R.M.; Sykes, R.

1996-01-01

The Buller Coalfield on the West Coast of the South Island, New Zealand, contains the Eocene Brunner Coal Measures. The coal measures unconformably overlie Paleozoic-Cretaceous basement rocks and are conformably overlain by, and laterally interfinger with, the Eocene marine Kaiata Formation. This study examines the lithofacies frameworks of the coal measures in order to interpret their depositional environments. The lower part of the coal measures is dominated by conglomeratic lithofacies that rest on a basal erosional surface and thicken in paleovalleys incised into an undulating peneplain surface. These lithofacies are overlain by sandstone, mudstone and organic-rich lithofacies of the upper part of the coal measures. The main coal seam of the organic-rich lithofacies is thick (10-20 m), extensive, locally split, and locally absent. This seam and associated coal seams in the Buller Coalfield are of low- to high-volatile bituminous rank (vitrinite reflectance between 0.65% and 1.75%). The main seam contains a variable percentage of ash and sulphur. These values are related to the thickening and areal distribution of the seam, which in turn, were controlled by the nature of clastic deposition and peat-forming mire systems, marine transgression and local tidal incursion. The conglomeratic lithofacies represent deposits of trunk and tributary braided streams that rapidly aggraded incised paleovalleys during sea-level stillstands. The main seam represents a deposit of raised mires that initially developed as topogenous mires on abandoned margins of inactive braidbelts. Peat accumulated in mires as a response to a rise in the water table, probably initially due to gradual sea-level rise and climate, and the resulting raised topography served as protection from floods. The upper part of the coal measures consists of sandstone lithofacies of flu vial origin and bioturbated sandstone, mudstone and organic-rich lithofacies, which represent deposits of paralic (deltaic, barrier shoreface, tidal and mire) and marine environments. The fluvial sandstone lithofacies accumulated in channels during a sea-level stillstand. The channels were infilled by coeval braided and meandering streams prior to transgression. Continued transgression, ranging from tidal channel-estuarine incursions to widespread but uneven paleoshoreline encroachment, accompanied by moderate basin subsidence, is marked by a stacked, back-stepping geometry of bioturbated sandstone and marine mudstone lithofacies. Final retrogradation (sea-level highstand) is marked by backfilling of estuaries and by rapid landward deposition of the marine Kaiata Formation in the late Eocene.

Survey of remote sensing applications

USGS Publications Warehouse

Deutsch, Morris

1974-01-01

Data from the first earth resources technology satellite (ERTS) as well as from NASA and other aircraft, contain much of the information indicative of the distribution of groundwater and the extent of its utilization. Thermal infrared imagery from aircraft is particularly valuable in studying groundwater discharge to the sea and other surface water bodies. Color infrared photography from aircraft and space is also used to locate areas of potential groundwater development. Anomalies in vegetation, soils, moisture, and their pattern of distribution may be indicative of underlying groundwater conditions. Remote sensing may be used directly or indirectly to identify stream reaches for test holes or production wells. Similarly, location of submarine springs increase effectiveness of groundwater exploration in the coastal zone.

Airborne ROWS data report for the high resolution experiment, June 1993

NASA Technical Reports Server (NTRS)

Vandemark, D.; Hines, D.; Bailey, S.; Stewart, K.

1994-01-01

Airborne radar ocean wave spectrometer (ROWS) data collected during the Office of Naval Research's High Resolution Remote Sensing Experiment of June 1993 are presented. This data summary covers six flights made using NASA's T-39 aircraft over a region of the North Atlantic off the coast of North Carolina and includes multiple crossings of the gulf stream. The Ku-band ROWS was operated in a configuration which continuously switched between an altimeter and a spectrometer channel. Data derived from the two channels include altimeter radar cross section, altimeter-derived sea surface mean square slope and wind speed, and directional and nondirectional longwave spectra. Discussion is provided for several events of particular interest.

The East Asian Jet Stream and Asian-Pacific-American Climate

NASA Technical Reports Server (NTRS)

Yang, Song; Lau, K.-M.; Kim, K.-M.

2000-01-01

The upper-tropospheric westerly jet stream over subtropical East Asia and western Pacific, often referred to as East Asian Jet (EAJ), is an important atmospheric circulation system in the Asian-Pacific-American (APA) region during winter. It is characterized by variabilities on a wide range of time scales and exerts a strong impact on the weather and climate of the region. On the synoptic scale, the jet stream is closely linked to many phenomena such as cyclogenesis, frontogenesis, blocking, storm track activity, and the development of other atmospheric disturbances. On the seasonal time scale, the variation of the EAJ determines many characteristics of the seasonal transition of the atmospheric circulation especially over East Asia. The variabilities of the EAJ on these time scales have been relatively well documented. It has also been understood since decades ago that the interannual. variability of the EAJ is associated with many climate signals in the APA region. These signals include the persistent anomalies of the East Asian winter monsoon and the changes in diabatic heating and in the Hadley circulation. However, many questions remain for the year-to-year variabilities of the EAJ and their relation to the APA climate. For example, what is the relationship between the EAJ and El Nino/Southern Oscillation (ENSO)? Will the EAJ and ENSO play different roles in modulating the APA climate? How is the jet stream linked to the non-ENSO-related sea surface temperature (SST) anomalies and to the Pacific/North American (PNA) teleconnection pattern?

Availability of streamflow for recharge of the basal aquifer in the Pearl Harbor area, Hawaii

USGS Publications Warehouse

Hirashima, George Tokusuke

1971-01-01

The Pearl Harbor area is underlain by an extensive basal aquifer that contains large supplies of fresh water. Because of the presence of a cap rock composed of sedimentary material that is less permeable than the basaltic lava of the basal aquifer, seaward movement of ground water is retarded. The cap rock causes the basal water to stand at a high level; thus, the lens of fresh water that floats on sea water is thick. Discharge from the basal ground-water body, which includes pumpage from wells and shafts, averaged 250 million gallons per day during 1931-65. Because the water level in the basal aquifer did not decline progressively, recharge to the ground-water body must have been approximately equal to discharge. Although pumping for agricultural use has decreased since 1931, net ground-water discharge has increased because of a large increase in pumping for urban use. Substitution of ground water for surface water in the irrigation of sugarcane has also contributed to a net increase in ground-water discharge. The development of Mililani Town will further increase discharge. The increase in ground-water discharge may cause an increase in chloride content of the water pumped from wells near the shore of Pearl Harbor unless the increased discharge is balanced by increased recharge to the local aquifer. The aquifer is recharged by direct infiltration and deep percolation of rain, principally in the high forested area, by infiltration and percolation of irrigation water applied in excess of plant requirements, by seepage of water through streambeds, and possibly by ground-water inflow from outside the area. Recharge is greatest in the uplands, where rainfall is heavy and where much infiltration takes place before rainwater collects in the middle and lower reaches of stream channels. Once water collects in and saturates the alluvium of stream channels, additional inflow to the streams will flow out to sea, only slightly decreased by seepage. Average annual direct runoff from the 90-square-mile Pearl Harbor area is 47.27 million gallons per day, or 11.1 inches; this is 13.3 percent of the average annual rainfall (83.3 in.) over the area. Average annual direct runoff in streams at the 800- and 400-foot altitudes is 29 and 38 million gallons per day, respectively. Kipapa Stream has the largest average annual direct runoff at those altitudes--6 and 9 million gallons per day, respectively. Because streams are flashy and have a wide range in discharge, only 60 percent of the average annual runoff can be economically diverted through ditches to recharge areas. The diversion may be increased slightly if reservoirs are used in conjunction with ditches to temporarily detain flows in excess of ditch capacity. The planned irrigation use of some of the perennial flow available in Waikele Stream near sea level will decrease pumping from and increase recharge to the basal aquifer. Suspended-sediment load is mainly silt and clay, and it increases rapidly with increased discharge. Thus, the use of streamflow for artificial recharge poses problems. High flows must be used if recharge is to be effective, but flows must not be so high as to cause clogging of recharge facilities with sediment or woodland debris. Practical tests are needed to determine the advantages and disadvantages of different types of recharge structures, such as a reservoir or basin, large-diameter deep shafts, deep wells, or combinations of all these structures.

Streaming current for particle-covered surfaces: simulations and experiments

NASA Astrophysics Data System (ADS)

Blawzdziewicz, Jerzy; Adamczyk, Zbigniew; Ekiel-Jezewska, Maria L.

2017-11-01

Developing in situ methods for assessment of surface coverage by adsorbed nanoparticles is crucial for numerous technological processes, including controlling protein deposition and fabricating diverse microstructured materials (e.g., antibacterial coatings, catalytic surfaces, and particle-based optical systems). For charged surfaces and particles, promising techniques for evaluating surface coverage are based on measurements of the electrokinetic streaming current associated with ion convection in the double-layer region. We have investigated the dependence of the streaming current on the area fraction of adsorbed particles for equilibrium and random-sequential-adsorption (RSA) distributions of spherical particles, and for periodic square and hexagonal sphere arrays. The RSA results have been verified experimentally. Our numerical results indicate that the streaming current weakly depends on the microstructure of the particle monolayer. Combining simulations with the virial expansion, we provide convenient fitting formulas for the particle and surface contributions to the streaming current as functions of area fractions. For particles that have the same ζ-potential as the surface, we find that surface roughness reduces the streaming current. Supported by NSF Award No. 1603627.

Temperature of the Gulf Stream

NASA Technical Reports Server (NTRS)

2002-01-01

The Gulf Stream is one of the strong ocean currents that carries warm water from the sunny tropics to higher latitudes. The current stretches from the Gulf of Mexico up the East Coast of the United States, departs from North America south of the Chesapeake Bay, and heads across the Atlantic to the British Isles. The water within the Gulf Stream moves at the stately pace of 4 miles per hour. Even though the current cools as the water travels thousands of miles, it remains strong enough to moderate the Northern European climate. The image above was derived from the infrared measurements of the Moderate-resolution Imaging Spectroradiometer (MODIS) on a nearly cloud-free day over the east coast of the United States. The coldest waters are shown as purple, with blue, green, yellow, and red representing progressively warmer water. Temperatures range from about 7 to 22 degrees Celsius. The core of the Gulf Stream is very apparent as the warmest water, dark red. It departs from the coast at Cape Hatteras, North Carolina. The cool, shelf water from the north entrains the warmer outflows from the Chesapeake and Delaware Bays. The north wall of the Gulf Stream reveals very complex structure associated with frontal instabilities that lead to exchanges between the Gulf Stream and inshore waters. Several clockwise-rotating warm core eddies are evident north of the core of the Gulf Stream, which enhance the exchange of heat and water between the coastal and deep ocean. Cold core eddies, which rotate counter clockwise, are seen south of the Gulf Stream. The one closest to Cape Hatteras is entraining very warm Gulf Stream waters on its northwest circumference. Near the coast, shallower waters have warmed due to solar heating, while the deeper waters offshore are markedly cooler (dark blue). MODIS made this observation on May 8, 2000, at 11:45 a.m. EDT. For more information, see the MODIS-Ocean web page. The sea surface temperature image was created at the University of Miami using the 11- and 12-micron bands, by Bob Evans, Peter Minnett, and co-workers.

Thermal evolutions of two kinds of melt pond with different salinity

NASA Astrophysics Data System (ADS)

Kim, Joo-Hong; Wilkinson, Jeremy; Moon, Woosok; Hwang, Byongjun; Granskog, Mats

2016-04-01

Melt ponds are water pools on sea ice. Their formation reduces ice surface albedo and alter surface energy balance, by which the ice melting and freezing processes are regulated. Thus, better understanding of their radiative characteristics has been vital to improve the simulation of melting/freezing of sea ice in numerical models. A melt pond would preserve nearly fresh water if it formed on multi-year ice and no flooding of sea water occurred, whereas a melt pond would contain more salty water if it formed on thinner and porous first-year ice, if there were an inflow of sea water by streams or cracks. One would expect that the fluid dynamic/thermodynamic properties (e.g., turbulence, stability, etc.) of pond water are influenced by the salinity, so that the response of pond water to any heat input (e.g., shortwave radiation) would be different. Therefore, better understanding of the salinity-dependent thermal evolution also has significant potential to improve the numerical simulation of the sea ice melting/freezing response to radiative thermal forcing. To observe and understand the salinity-dependent thermal evolution, two ice mass balance buoys (IMBs) were deployed in two kinds (fresh and salty) of melt pond on a same ice floe on 13 August 2015 during Araon Arctic cruise. The thermistor chain, extending from the air through the pond and ice into the sea water, was deployed through a drilled borehole inside the pond. Besides, the IMBs were also accompanied with three broadband solar radiation sensors (two (up and down) in the air over melt pond and one upward-looking under sea ice) to measure the net shortwave radiation at the pond surface and the penetrating solar radiation through ice. Also, the web camera was installed to observe any updates in the conditions of equipment and surrounding environment (e.g., weather, surface state, etc.). On the date of deployment, the fresh pond had salinity of 2.3 psu, light blue color, lots of slush ice particles which increased opacity, and under-pond ice thickness of 219 cm, whereas the salty pond had salinity of 20 psu, dark blue color, only transparent water, and under-pond ice thickness of 100 cm. Temporal evolutions of mean water temperature of the two ponds are contrasted and showed that the fresh pond had about 1degC warmer temperature than the salty pond. The existence of slush ice particles in the pond seems to be responsible for this temperature difference. Multiple scattering by slush ice particles could lead to more absorption of shortwave radiation. A comparison of vertical profiles of water temperature shows that there existed an internal maximum heating layer in the fresh pond. Possibly, this profile might indicate the the below layer unstable, which might have efficient thermal propagation to the ice surface. On the other hand, the vertical temperature profile of the salty pond had internal thermocline near the pond bottom, but so that the upper heating may not efficiently propagate downward to the ice surface.

Interannual Variations of Surface Currents and Transports in the Sicily Channel Derived From Coastal Altimetry

NASA Astrophysics Data System (ADS)

Jebri, Fatma; Zakardjian, Bruno; Birol, Florence; Bouffard, Jérôme; Jullion, Loïc.; Sammari, Cherif

2017-11-01

A 20 year coastal altimetry data set (X-TRACK) is used, for the first time, to gain insight into the long-term interannual variations of the surface circulation in the Sicily Channel. First, a spectral along with a time/space diagram analysis are applied to the monthly means. They reveal a regionally coherent current patterns from track to track with a marked interannual variability that is unequally shared between the Atlantic Tunisian Current and Atlantic Ionian Stream inflows in the Sicily Channel and the Bifurcation Tyrrhenian Current outflow northeast of Sicily. Second, an empirical altimetry-based transport-like technique is proposed to quantify volume budgets inside the closed boxes formed by the crossing of the altimetry tracks and coastlines over the study area. A set of hydrographic measurements is used to validate the method. The inferred altimetry transports give a well-balanced mean eastward Atlantic Waters baroclinic flow of 0.4 Sv and standard deviations of 0.2 Sv on a yearly basis throughout the Sicily Channel and toward the Ionian Sea, which is fairly coherent with those found in the literature. Furthermore, the analysis allows to quantify the intrusions of Atlantic Waters over the Tunisian Shelf (0.12 ± 0.1 Sv) and highlights two main modes of variability of the main surface waters path over the Sicily Channel through the Bifurcation Atlantic Tunisian Current and Atlantic Ionian Stream systems. Some physical mechanisms are finally discussed with regards to changes in the observed currents and transports.

2D fluorescence spectroscopy for monitoring ion-exchange membrane based technologies - Reverse electrodialysis (RED).

PubMed

Pawlowski, Sylwin; Galinha, Claudia F; Crespo, João G; Velizarov, Svetlozar

2016-01-01

Reverse electrodialysis (RED) is one of the emerging, membrane-based technologies for harvesting salinity gradient energy. In RED process, fouling is an undesirable operation constraint since it leads to a decrease of the obtainable net power density due to increasing stack electric resistance and pressure drop. Therefore, early fouling detection is one of the main challenges for successful RED technology implementation. In the present study, two-dimensional (2D) fluorescence spectroscopy was used, for the first time, as a tool for fouling monitoring in RED. Fluorescence excitation-emission matrices (EEMs) of ion-exchange membrane surfaces and of natural aqueous streams were acquired during one month of a RED stack operation. Fouling evolvement on the ion-exchange membrane surfaces was successfully followed by 2D fluorescence spectroscopy and quantified using principal components analysis (PCA). Additionally, the efficiency of cleaning strategy was assessed by measuring the membrane fluorescence emission intensity before and after cleaning. The anion-exchange membrane (AEM) surface in contact with river water showed to be significantly affected due to fouling by humic compounds, which were found to cross through the membrane from the lower salinity (river water) to higher salinity (sea water) stream. The results obtained show that the combined approach of using 2D fluorescence spectroscopy and PCA has a high potential for studying fouling development and membrane cleaning efficiency in ion exchange membrane processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

The paradox of a long grounding during West Antarctic Ice Sheet retreat in Ross Sea.

PubMed

Bart, Philip J; Krogmeier, Benjamin J; Bart, Manon P; Tulaczyk, Slawek

2017-04-28

Marine geological data show that the West Antarctic Ice Sheet (WAIS) advanced to the eastern Ross Sea shelf edge during the Last Glacial Maximum (LGM) and eventually retreated ~1000 km to the current grounding-line position on the inner shelf. During the early deglacial, the WAIS deposited a voluminous stack of overlapping grounding zone wedges (GZWs) on the outer shelf of the Whales Deep Basin. The large sediment volume of the GZW cluster suggests that the grounding-line position of the paleo-Bindschadler Ice Stream was relatively stationary for a significant time interval. We used an upper bound estimate of paleo-sediment flux to investigate the lower bound duration over which the ice stream would have deposited sediment to account for the GZW volume. Our calculations show that the cluster represents more than three millennia of ice-stream sedimentation. This long duration grounding was probably facilitated by rapid GZW growth. The subsequent punctuated large-distance (~200 km) grounding-line retreat may have been a highly non-linear ice sheet response to relatively continuous external forcing such as gradual climate warming or sea-level rise. These findings indicate that reliable predictions of future WAIS retreat may require incorporation of realistic calculations of sediment erosion, transport and deposition.

Assessment of tidal circulation and tidal current asymmetry in the Iroise sea with specific emphasis on characterization of tidal energy resources around the Ushant Island.

NASA Astrophysics Data System (ADS)

Thiébaut, Maxime; Sentchev, Alexei

2015-04-01

We use the current velocity time series recorded by High Frequency Radars (HFR) to study circulation in highly energetic tidal basin - the Iroise sea. We focus on the analysis of tidal current pattern around the Ushant Island which is a promising site of tidal energy. The analysis reveals surface current speeds reaching 4 m/s in the North of Ushant Island and in the Fromveur Strait. In these regions 1 m/s is exceeded 60% of time and up to 70% of time in center of Fromveur. This velocity value is particularly interesting because it represents the cut-in-speed of the most of marine turbine devices. Tidal current asymmetry is not always considered in tidal energy site selection. However, this quantity plays an important role in the quantification of hydrokinetic resources. Current velocity times series recorded by HFR highlights the existence of a pronounced asymmetry in current magnitude between the flood and ebb tide ranging from -0.5 to more 2.5. Power output of free-stream devices depends to velocity cubed. Thus a small current asymmetry can generate a significant power output asymmetry. Spatial distribution of asymmetry coefficient shows persistent pattern and fine scale structure which were quantified with high degree of accuracy. The particular asymmetry evolution on both side of Fromveur strait is related to the spatial distribution of the phase lag of the principal semi-diurnal tidal constituent M2 and its higher order harmonics. In Fromveur, the asymmetry is reinforced due to the high velocity magnitude of the sixth-diurnal tidal harmonics. HF radar provides surface velocity speed, however the quantification of hydrokinetic resources has to take into account the decreasing of velocity with depth. In order to highlight this phenomenon, we plot several velocity profiles given by an ADCP which was installed in the HFR study area during the same period. The mean velocity in the water column calculated by using the ADCP data show that it is about 80% of the surface current speed. We consider this value in our calculation of power to make the power estimation of marine turbine devices more realistic. Finally, we demonstrate that in the region of opposing flood-versus ebb-dominated asymmetry occurring over limited spatial scale, it is possible to aggregated free-stream devices to provide balanced power generation over the tidal cycle. Keywords : Tidal circulation, current asymmetry, tidal energy, HF radar, Iroise Sea.

The Effect of Aerosols and Clouds on the Retrieval of Infrared Sea Surface Temperatures

NASA Technical Reports Server (NTRS)

Vazquez-Cuervo, Jorge; Armstrong, Edward M.; Harris, Andy

2004-01-01

Comparisons are performed between spatially averaged sea surface temperatures (ASST2) as derived from the second Along-Track Scanning Radiometer (ATSR-2) on board the second European Remote Sensing Satellite (ERS-2) and the NOAA-NASA Advanced Very High Resolution Radiometer (AVHRR) Oceans Pathfinder dataset (MPFSST). Difference maps, MPFSST 2 ASST2, along with the application of a simple statistical regression model to aerosol and cloud data from the Total Ozone Mapping Spectrometer ( TOMS), are used to examine the impact of possible aerosol and cloud contamination. Differences varied regionally, but the largest biases were seen off western Africa. Nighttime and daytime differences off western Africa were reduced from -0.5degrees to -0.2degreesC and from -0.1degrees to 0degreesC, respectively. Significant cloud flagging, based on the model, occurred in the Indian Ocean, the equatorial Pacific, and in the vicinity of the Gulf Stream. Comparisons of the MPFSST and the ASST2 with in situ data from the 2002 version of the World Oceanic Database (WOD02) off western Africa show larger mean differences for the MPFSST. The smallest mean differences occurred for nighttime ASST2 - WOD02 with a value of 0.0degrees +/- 0.4degreesC.

Surface Water in Hawaii

USGS Publications Warehouse

Oki, Delwyn S.

2003-01-01

Surface water in Hawaii is a valued resource as well as a potential threat to human lives and property. The surface-water resources of Hawaii are of significant economic, ecologic, cultural, and aesthetic importance. Streams supply more than 50 percent of the irrigation water in Hawaii, and although streams supply only a few percent of the drinking water statewide, surface water is the main source of drinking water in some places. Streams also are a source of hydroelectric power, provide important riparian and instream habitats for many unique native species, support traditional and customary Hawaiian gathering rights and the practice of taro cultivation, and possess valued aesthetic qualities. Streams affect the physical, chemical, and aesthetic quality of receiving waters, such as estuaries, bays, and nearshore waters, which are critical to the tourism-based economy of the islands. Streams in Hawaii pose a danger because of their flashy nature; a stream's stage, or water level, can rise several feet in less than an hour during periods of intense rainfall. Streams in Hawaii are flashy because rainfall is intense, drainage basins are small, basins and streams are steep, and channel storage is limited. Streamflow generated during periods of heavy rainfall has led to loss of property and human lives in Hawaii. Most Hawaiian streams originate in the mountainous interiors of the islands and terminate at the coast. Streams are significant sculptors of the Hawaiian landscape because of the erosive power of the water they convey. In geologically young areas, such as much of the southern part of the island of Hawaii, well-defined stream channels have not developed because the permeability of the surface rocks generally is so high that rainfall infiltrates before flowing for significant distances on the surface. In geologically older areas that have received significant rainfall, streams and mass wasting have carved out large valleys.

Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature

NASA Astrophysics Data System (ADS)

Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio

2017-07-01

This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two drier subperiods, which mostly show air humidity divergence. While the drier periods are particularly characterized by the strengthening of northerly wind over the center of South America, including the Pantanal region, the wetter period is characterized by its weakening. The circulation pattern at 850 hPa levels during the drier subperiods shows anticyclonic anomalies centered over east central South America. Also, the drier subperiods (1st and 3rd) are characterized by negative stream function anomalies over southeastern South America and adjacent South Atlantic, and the wetter subperiod is characterized by positive stream function anomalies. In the three subperiods, one can see mean atmospheric patterns associated with Rossby wave propagation coming from the South Pacific basin—similar to the Pacific South America pattern, but with reverse signals between the wetter and the drier periods. This result suggests a possible relationship between climatic patterns over southeastern South America regions and the Pacific conditions in a decadal scale.

A Improved Seabed Surface Sand Sampling Device

NASA Astrophysics Data System (ADS)

Luo, X.

2017-12-01

In marine geology research it is necessary to obtain a suf fcient quantity of seabed surface samples, while also en- suring that the samples are in their original state. Currently,there are a number of seabed surface sampling devices available, but we fnd it is very diffcult to obtain sand samples using these devices, particularly when dealing with fne sand. Machine-controlled seabed surface sampling devices are also available, but generally unable to dive into deeper regions of water. To obtain larger quantities of seabed surface sand samples in their original states, many researchers have tried to improve upon sampling devices,but these efforts have generally produced ambiguous results, in our opinion.To resolve this issue, we have designed an improved andhighly effective seabed surface sand sampling device that incorporates the strengths of a variety of sampling devices. It is capable of diving into deepwater to obtain fne sand samples and is also suited for use in streams, rivers, lakes and seas with varying levels of depth (up to 100 m). This device can be used for geological mapping, underwater prospecting, geological engineering and ecological, environmental studies in both marine and terrestrial waters.

An Autonomous, Low Cost Platform for Seafloor Geodetic Observations

NASA Astrophysics Data System (ADS)

Ericksen, T.; Foster, J. H.; Bingham, B. S.

2013-12-01

The high cost of acquiring geodetic data from the sea floor has limited the observations available to help us understand and model the behavior of seafloor geodetic processes. To address this problem, the Pacific GPS Facility at the University of Hawaii is developing a cost effective approach for accurately measuring short-term vertical motions of the seafloor and maintaining a continuous long-term record of seafloor pressure without the requirement for costly ship time. There is a recognized need to vastly increase our underwater geodetic observing capacity. Most of the largest recorded earthquakes and most devastating tsunamis are generated at subduction zones underwater. Similarly, many volcanoes are partly (e.g. Santorini) or completely (e.g. Loihi) submerged, and are not well observed and understood. Furthermore, landslide features ring many ocean basins, and huge debris deposits surround many volcanic oceanic islands. Our approach will lower the cost of collecting sea-floor geodetic data, reducing the barriers preventing us from acquiring the information we need to observe and understand these types of structures and provide a direct societal benefit in improving hazard assessment. The capability is being developed by equipping one of the University of Hawaii Wave Gliders with an integrated acoustic telemetry package, a dual frequency geodetic-grade Global Positioning System (GPS) receiver, processing unit, and cellular communications. The Wave Glider will interrogate high accuracy pressure sensors on the sea floor to maintain a near-continuous stream of pressure and temperature data, but seafloor pressure data includes contribution from a variety of sources and on its own may not provide the accuracy required for geodetic investigations. Independent measurements of sea surface pressure and sea surface height can be used to remove these contributions from the observed sea floor pressure timeseries. We will integrate our seafloor pressure measurements with air pressure data, and precise vertical measurements of the sea surface from kinematic positioning of the Wave Glider over the bottom sensor, to determine cm-scale vertical seafloor motions. The seafloor package will consist of a simple tripod frame that seats the pressure sensor unit, and includes an attachment onto which an ROV can install a mobile pressure recorder (MPR) should ship and ROV time be available. Two visits with an MPR would allow calibration of the linear drift of the continuous sensor, further enhancing the value of the timeseries. The pressure sensor is recoverable and serviceable and using the MPR calibration will enable the seafloor monument to be re-occupied to extend the pressure record beyond a single 5+ year deployment. We are currently focused on retrieving high accuracy vertical sea floor motions, but, importantly, we have chosen a development approach that provides a simple upgrade path for incorporating the Wave Glider GPS-Acoustic (GPS/A) measurement system under development at SIO. With this upgrade, Wave Gliders could also acquire accurate horizontal motions of the sea floor sensors, and provide a cost-effective way of performing full, 3-dimensional, surveys of sea-floor motions.

Nonmigratory, 12-kHz, deep scattering layers of Sargasso Sea origin in warm-core rings

NASA Astrophysics Data System (ADS)

Conte, Maureen H.; Bishop, James B.; Backus, Richard H.

1986-11-01

Nonmigratory, 12-kHz, deep sound-scattering layers (NMDSLs) were entrained within Sargasso Sea-Gulf Stream waters during the formation of warm-core rings 82B and 82H. At night ring water was easily distinguished from Slope Water by the presence of these well-developed features between 200 and 550 m. The distribution of NMDSLs in 82H as a function of temperature and salinity matched Sargasso Sea distributions, indicating that Sargasso Sea water was present in the center of 82H at the time of its formation. However, the distribution of NMDSLs in the center of 82B a few weeks after its formation was more consistent with the distribution found in Gulf Stream-Sargasso Sea edge water. NMDSLs were a persistent feature of the lower thermostad and upper thermocline of 82B. Their distribution in the upper thermocline approximately paralleled the decrease in thickness of the thermostad and became shallower with increasing distance from ring center. The NMDSLs disappeared at the ring edge when the bottom of the thermostad became shallower than about 100 m. Their distribution within 30 km of ring center changed very little between April and June, whereas those found in the thermocline at greater distances from ring center showed greater dispersion with respect to temperature. Following several Gulf Stream interactions in July, the NMDSLs were significantly shallower, and lay in colder water. The continued presence of the deep NMDSLs in the thermocline, even though the latter was nearly 100 m shallower, indicates that the remaining thermocline had not been significantly exchanged with Gulf Stream or Slope Water during the interactions. The changes in the temperature of the water in which the NMDSLs were found in August suggest that core waters (30 km from ring center in June) were resorbed by the Gulf Stream and that only waters of 30 km radius remained to reform the ring. We found no evidence that the animals composing the NMDSLs adjusted their vertical distributions in response to changes in environmental properties; rather, the temporal changes we observed are best explained by the physical processes affecting ring structure. No qualitative decrease in NMDSL intensity was observed in 82B between April and August, suggesting that the sound scatterers can tolerate significant changes in depth, temperature and salinity. The gonostomatid fish Cyclothone braueri and the physonect siphonophores are possibly sources of the NMDSLs.

Sea Surface Temperature and Ocean Color Variability in the South China Sea

NASA Astrophysics Data System (ADS)

Conaty, A. P.

2001-12-01

The South China Sea is a marginal sea in the Southeast Asian region whose surface circulation is driven by monsoons and whose surface currents have complex seasonal patterns. Its rich natural resources and strategic location have made its small islands areas of political dispute among the neighboring nations. This study aims to show the seasonal and interannual variability of sea surface temperature and ocean color in South China Sea. It makes use of NOAA's Advanced Very High Resolution Radiometer (AVHRR) satellite data sets on sea surface temperature for the period 1981-2000 and NASA's Nimbus-7 Coastal Zone Color Scanner (CZCS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite data sets on pigment concentration (ocean color) for the period 1981-1996 and 1997-2000, respectively. Transect lines were drawn along several potential hotspot areas to show the variability in sea surface temperature and pigment concentration through time. In-situ data on sea surface temperature along South China Sea were likewise plotted to see the variability with time. Higher seasonal variability in sea surface temperature was seen at higher latitudes. Interannual variability was within 1-3 Kelvin. In most areas, pigment concentration was higher during northern hemisphere winter and autumn, after the monsoon rains, with a maximum of 30 milligrams per cubic meter.

Patterns and drivers for wetland connections in the Prairie Pothole Region, United States

USGS Publications Warehouse

Vanderhoof, Melanie; Christensen, Jay R.; Alexander, Laurie C.

2017-01-01

Ecosystem function in rivers, lakes and coastal waters depends on the functioning of upstream aquatic ecosystems, necessitating an improved understanding of watershed-scale interactions including variable surface-water flows between wetlands and streams. As surface water in the Prairie Pothole Region expands in wet years, surface-water connections occur between many depressional wetlands and streams. Minimal research has explored the spatial patterns and drivers for the abundance of these connections, despite their potential to inform resource management and regulatory programs including the U.S. Clean Water Act. In this study, wetlands were identified that did not intersect the stream network, but were shown with Landsat images (1990–2011) to become merged with the stream network as surface water expanded. Wetlands were found to spill into or consolidate with other wetlands within both small (2–10 wetlands) and large (>100 wetlands) wetland clusters, eventually intersecting a stream channel, most often via a riparian wetland. These surface-water connections occurred over a wide range of wetland distances from streams (averaging 90–1400 m in different ecoregions). Differences in the spatial abundance of wetlands that show a variable surface-water connection to a stream were best explained by smaller wetland-to-wetland distances, greater wetland abundance, and maximum surface-water extent. This analysis demonstrated that wetland arrangement and surface water expansion are important mechanisms for depressional wetlands to connect to streams and provides a first step to understanding the frequency and abundance of these surface-water connections across the Prairie Pothole Region.

Subseasonal Reversal of East Asian Surface Temperature Variability in Winter 2014/15

NASA Astrophysics Data System (ADS)

Xu, Xinping; Li, Fei; He, Shengping; Wang, Huijun

2018-06-01

Although there has been a considerable amount of research conducted on the East Asian winter-mean climate, subseasonal surface air temperature (SAT) variability reversals in the early and late winter remain poorly understood. In this study, we focused on the recent winter of 2014/15, in which warmer anomalies dominated in January and February but colder conditions prevailed in December. Moreover, Arctic sea-ice cover (ASIC) in September-October 2014 was lower than normal, and warmer sea surface temperature (SST) anomalies occurred in the Niño4 region in winter, together with a positive Pacific Decadal Oscillation (PDO|+) phase. Using observational data and CMIP5 historical simulations, we investigated the PDO|+ phase modulation upon the winter warm Niño4 phase (autumn ASIC reduction) influence on the subseasonal SAT variability of East Asian winter. The results show that, under a PDO|+ phase modulation, warm Niño4 SST anomalies are associated with a subseasonal delay of tropical surface heating and subsequent Hadley cell and Ferrel cell intensification in January-February, linking the tropical and midlatitude regions. Consistently, the East Asian jet stream (EAJS) is significantly decelerated in January-February and hence promotes the warm anomalies over East Asia. Under the PDO|+ phase, the decrease in ASIC is related to cold SST anomalies in the western North Pacific, which increase the meridional temperature gradient and generate an accelerated and westward-shifted EAJS in December. The westward extension of the EAJS is responsible for the eastward-propagating Rossby waves triggered by declining ASIC and thereby favors the connection between ASIC and cold conditions over East Asia.

Long-term patterns and short-term dynamics of stream solutes and suspended sediment in a rapidly weathering tropical watershed

NASA Astrophysics Data System (ADS)

Shanley, James B.; McDowell, William H.; Stallard, Robert F.

2011-07-01

The 326 ha Río Icacos watershed in the tropical wet forest of the Luquillo Mountains, northeastern Puerto Rico, is underlain by granodiorite bedrock with weathering rates among the highest in the world. We pooled stream chemistry and total suspended sediment (TSS) data sets from three discrete periods: 1983-1987, 1991-1997, and 2000-2008. During this period three major hurricanes crossed the site: Hugo in 1989, Hortense in 1996, and Georges in 1998. Stream chemistry reflects sea salt inputs (Na, Cl, and SO4), and high weathering rates of the granodiorite (Ca, Mg, Si, and alkalinity). During rainfall, stream composition shifts toward that of precipitation, diluting 90% or more in the largest storms, but maintains a biogeochemical watershed signal marked by elevated K and dissolved organic carbon (DOC) concentration. DOC exhibits an unusual "boomerang" pattern, initially increasing with flow but then decreasing at the highest flows as it becomes depleted and/or vigorous overland flow minimizes contact with watershed surfaces. TSS increased markedly with discharge (power function slope 1.54), reflecting the erosive power of large storms in a landslide-prone landscape. The relations of TSS and most solute concentrations with stream discharge were stable through time, suggesting minimal long-term effects from repeated hurricane disturbance. Nitrate concentration, however, increased about threefold in response to hurricanes then returned to baseline over several years following a pseudo first-order decay pattern. The combined data sets provide insight about important hydrologic pathways, a long-term perspective to assess response to hurricanes, and a framework to evaluate future climate change in tropical ecosystems.

Long-term patterns and short-term dynamics of stream solutes and suspended sediment in a rapidly weathering tropical watershed

USGS Publications Warehouse

Shanley, James B.; McDowell, William H.; Stallard, Robert F.

2011-01-01

The 326 ha Río Icacos watershed in the tropical wet forest of the Luquillo Mountains, northeastern Puerto Rico, is underlain by granodiorite bedrock with weathering rates among the highest in the world. We pooled stream chemistry and total suspended sediment (TSS) data sets from three discrete periods: 1983-1987, 1991-1997, and 2000-2008. During this period three major hurricanes crossed the site: Hugo in 1989, Hortense in 1996, and Georges in 1998. Stream chemistry reflects sea salt inputs (Na, Cl, and SO4), and high weathering rates of the granodiorite (Ca, Mg, Si, and alkalinity). During rainfall, stream composition shifts toward that of precipitation, diluting 90% or more in the largest storms, but maintains a biogeochemical watershed signal marked by elevated K and dissolved organic carbon (DOC) concentration. DOC exhibits an unusual "boomerang" pattern, initially increasing with flow but then decreasing at the highest flows as it becomes depleted and/or vigorous overland flow minimizes contact with watershed surfaces. TSS increased markedly with discharge (power function slope 1.54), reflecting the erosive power of large storms in a landslide-prone landscape. The relations of TSS and most solute concentrations with stream discharge were stable through time, suggesting minimal long-term effects from repeated hurricane disturbance. Nitrate concentration, however, increased about threefold in response to hurricanes then returned to baseline over several years following a pseudo first-order decay pattern. The combined data sets provide insight about important hydrologic pathways, a long-term perspective to assess response to hurricanes, and a framework to evaluate future climate change in tropical ecosystems.

Long-term patterns and short-term dynamics of stream solutes and suspended sediment in a rapidly weathering tropical watershed

USGS Publications Warehouse

Shanley, J.B.; McDowell, W.H.; Stallard, R.F.

2011-01-01

The 326 ha R??o Icacos watershed in the tropical wet forest of the Luquillo Mountains, northeastern Puerto Rico, is underlain by granodiorite bedrock with weathering rates among the highest in the world. We pooled stream chemistry and total suspended sediment (TSS) data sets from three discrete periods: 1983-1987, 1991-1997, and 2000-2008. During this period three major hurricanes crossed the site: Hugo in 1989, Hortense in 1996, and Georges in 1998. Stream chemistry reflects sea salt inputs (Na, Cl, and SO4), and high weathering rates of the granodiorite (Ca, Mg, Si, and alkalinity). During rainfall, stream composition shifts toward that of precipitation, diluting 90% or more in the largest storms, but maintains a biogeochemical watershed signal marked by elevated K and dissolved organic carbon (DOC) concentration. DOC exhibits an unusual "boomerang" pattern, initially increasing with flow but then decreasing at the highest flows as it becomes depleted and/or vigorous overland flow minimizes contact with watershed surfaces. TSS increased markedly with discharge (power function slope 1.54), reflecting the erosive power of large storms in a landslide-prone landscape. The relations of TSS and most solute concentrations with stream discharge were stable through time, suggesting minimal long-term effects from repeated hurricane disturbance. Nitrate concentration, however, increased about threefold in response to hurricanes then returned to baseline over several years following a pseudo first-order decay pattern. The combined data sets provide insight about important hydrologic pathways, a long-term perspective to assess response to hurricanes, and a framework to evaluate future climate change in tropical ecosystems. Copyright 2011 by the American Geophysical Union.

New deglacial and Holocene micropaleontological and geochemical records from the southern margin of the Svalbard Archipelago (Arctic Ocean)

NASA Astrophysics Data System (ADS)

Rigual-Hernández, Andrés.

2010-05-01

This study is presented in the context of the Spanish research project "The development of an Arctic ice stream-dominated sedimentary system: The southern Svalbard continental margin" (SVAIS), developed within the framework of the International Polar Year (IPY) Activity N. 367 (NICE STREAMS). Its main goal is to understand the evolution of glacial continental margins and their relationship with the changes in ice sheet dynamics induced by natural climatic changes, combining the geophysical data with the sediment record both collected during an oceanographic cruise in the Storfjorden area (SW Svalbard margin) in August 2007. This marine depositional system, dominated by an ice stream during the last glacial period, was selected due to its small size inducing a rapid response to climatic changes, and for the oceanographic relevance of the area for global ocean circulation. The results obtained aim to define the sedimentary architecture and morphology, and to provide more insight into the paleoceanographic and paleoclimatic evolution of the region. We specifically report on new micropaleontological and geochemical data obtained from the sediment cores. A preliminary age model indicates that the sediment sequences cover approximately the Last Deglaciation and the Holocene. Microfossils are generally well preserved, although the abundances of the different groups show marked shifts along the record. Low concentrations of coccolithophores, diatoms, planktic foraminifers and cysts of organic-walled dinoflagellates (dinocysts) are found at the lower half of the sequence (IRD-rich, coarser-grained sediments), and increase towards the Late Holocene (fine-grained bioturbated sediments). The Climatic Optimum is characterized by the warmest sea surface temperatures as estimated from the fossil assemblage, diverse transfer functions and biogeochemical proxies, and by high nutrient contents in the bottom waters shown by light carbon isotope values and high Cd/Ca ratios in benthic foraminifers. Dilution by terrigenous material, related to the retreat of the Barents Sea Ice Sheet in response to changes in the strength of the Atlantic-sourced, warm Western Spitsbergen Current, seems to be important in driving the abundances of microfossils and of organic compounds. The different stages of the Deglaciation and the Holocene and the associated modifications in the surface oceanic environment are documented by changes in the fossil assemblage composition of the different microfossil groups, while synchronous changes in the bottom water masses are registered by stable isotope and trace element analyses of benthic foraminifers.

Variability of sea-surface temperature in the South Atlantic bight as observed from satellite: Implications for offshore-spawning fish

NASA Astrophysics Data System (ADS)

Stegmann, P. M.; Yoder, J. A.

1996-06-01

We examined full-resolution (1 × 1 km) satellite images of sea-surface temperature (SST) over five consecutive years (1981-1986) covering the Atlantic menhaden ( Brevoortia tyrannus) recruitment period (November-April) in the SABRE (South Atlantic Bight recruitment experiment) study site. The results of our image time series indicated two processes which could be possible mechanisms for the onshore transport of fish larvae into coastal regions. One is the influx of warm Gulf Stream water that oscillates in and out of the Carolina Bays. These oscillations occurred throughout the study period over distances of 20-40 km and on time-scales as short as two days. The other is a tongue of relatively cold water located adjacent to the Virginia coast that moved southward and penetrated into Onslow Bay between January and March. Previous studies showed that Atlantic menhaden preferentially spawn in 18-22°C waters on the outer shelf. On the assumption that the 18°C isotherm (18DI) indicates where high larval abundance may occur, we used AVHRR-SST imagery to track the onshore-offshore movement of the 18DI along a transect extending onshore-offshore in Onslow Bay. Owing to seasonal warming and cooling, this isotherm was always found closest to the coast in early November, reached maximum offshore displacement by January/March, and then moved onshore again in April/May. Our results also showed that the position of this isotherm can move offshore or onshore in a matter of a few days. An important influence and possibly the major cause of the higher frequency displacements of the 18DI are Gulf Stream meanders or filaments moving through Onslow Bay. Our estimates of onshore isotherm speeds as determined from satellite SST ranged from 2 to 25 cm s -1 and are within the same order as those calculated by physical models or larval age determinations. If the onshore pulses of warm Gulf Stream water are indeed a mode by which menhaden larvae are transported cross-shelf, then the use of satellite-based observations to determine their frequency and onshore extent, as done in the present study, is a useful tool to study variations in fish recruitment.

Characterising the spatial variability of the tidal stream energy resource from floating turbines

NASA Astrophysics Data System (ADS)

Ward, Sophie; Neill, Simon; Robins, Peter

2017-04-01

The shelf seas, in particular the northwest European shelf seas surrounding the UK, contain significant tidal power potential. Tidal stream energy is both predictable and reliable providing that sites are well-selected based upon the hydrodynamic regime and the device specifics. In this high resolution three-dimensional tidal modelling study, we investigate how the tidal stream resource around the Welsh coast (UK) varies with water depth and location, with particular focus on the Pembrokeshire region. The potential extractable energy for a floating tidal stream energy converter is compared with that for a bottom-fixed device, highlighting the need to vary the resource characterisation criteria based on device specifics. We demonstrate how small variations in the tidal current speeds - with hub depth or due to tidal asymmetry - can lead to substantial variations in potential power output. Further, the results indicate that power generation from floating tidal energy converters will be more significantly influenced by tidal elevations in regions characterised by a lower tidal range (more progressive waves) than regions that experience a high tidal range (standing waves). As numerical modelling capacity improves and tidal stream energy converter technologies develop, ongoing improved quantification of the tidal resource is needed, as well as consideration of the possible feedbacks of the devices and energy extraction on the hydrodynamic regime and the surrounding area.

Geoengineering Outlet Glaciers and Ice Streams

NASA Astrophysics Data System (ADS)

Wolovick, Michael

2017-04-01

Mass loss from Greenland and Antarctica is highly sensitive to the presence of warm ocean water that drives melting of ice shelves and marine terminated glaciers. This warm water resides offshore at depth and accesses the grounding line through deep but narrow troughs and fjords. Here, we investigate the possibility of blocking warm water transport through these choke points with an artificial sill. Using a simple width-averaged model of ice stream flow coupled to a buoyant-plume model of submarine melt, we find that grounding line retreat and sea level rise can be delayed or reversed for hundreds of years if warm water is prevented from accessing outlet glaciers and ice-shelf cavities. Glaciers with a floating shelf exhibit a strong response to the presence of the artificial sill regardless of our choice of calving law, while tidewater glaciers require a strong linkage between submarine melt and iceberg calving for the artificial sill to have an effect. As a result of this difference and as a result of differing degrees of overdeepening in the basal topography, Antarctica and Greenland present very different societal cost-benefit analyses. Intervention in Greenland would be low-cost and low-reward: the volume of the artificial sill is comparable to existing large public works projects such as the Dubai Islands or the Suez Canal, but the magnitude of averted sea-level rise is small, the success of the intervention depends on the choice of calving law, and the glaciers return to their non-geoengineered trajectories within one to two centuries. Intervention in Antarctica, on the other hand, would be high-cost and high-reward: the volume of the artificial sill is one to two orders of magnitude greater, but the averted sea level rise is much larger, the intervention is successful regardless of the choice of calving law, and the ice streams remain far from their non-geoengineered trajectories throughout the 1000 year duration of our model runs. In both cases, an artificial sill cannot save the glaciers forever if the climate continues to warm and surface melt continues to increase, but glacial geoengineering may offer society a way to delay irreversible grounding line retreat and thus buy time while emissions reduction and carbon removal efforts are underway.

Preserved Crevasse Casts in the Whales Deep Basin, eastern Ross Sea

NASA Astrophysics Data System (ADS)

Bart, P. J.; Tulaczyk, S. M.

2017-12-01

A recent seismic stratigraphic study showed that the large bathymetric saddle in the Whales Deep Basin in eastern Ross Sea is a compound grounding zone wedge (CGZW). The basin was occupied by the paleo Bindschadler Ice Stream when grounded ice advanced to the outer continental shelf during the last glacial maximum (LGM). The CGZW is composed of at least seven overlapping GZWs. The crest of the bathymetric saddle corresponds to the grounding zone of GZW7, i.e., the seventh GZW. The north face of the saddle is essentially equivalent to the GZW7 foreset and the south side of the saddle is the GZW7 topset, i.e., the seafloor surface to which the paleo Bindschadler Ice Stream was grounded. The GZW7 topset is mantled by a series of relatively small-amplitude, but very long, ridges with low sinuosity. These ridges were previously imaged by Mosola and Anderson (2006). Here we show a larger-area multibeam survey that was acquired in 2015 during expedition NBP1502B. The larger-area multibeam survey shows that the ridges have amplitudes ranging from 2 to 11 m above grade and have an overall northeast-southwest orientation over an area of at least 500 km2 on the central and western flank of Whales Deep Basin middle continental shelf in water depths ranging from 500 to 550 m. The ridges have spacing that mostly range between 1 and 2 km. The longest ridges are observed to be 40 km. The ridges in the center of the trough have flatter tops than those in the shallower water on the flank of Houtz Bank. In our ongoing investigation of these interesting features, we hypothesize that the ridges formed below a rapidly flowing ice stream as it thinned and was decoupling from the bed towards the end of GZW7 deposition. High ice deformation rates accompanying this process caused the development of large basal crevasses or ice shelf rifts that reached the seafloor. Subglacial till was scraped and collected into lower parts of these crevasses/rifts. Chronologic data indicates that these crevasse casts formed during rapid sea-level rise at 11.5 kyr BP, i.e., during MWP1B, which partly explains their amazing preservation. These casts suggest abrupt ice thinning and bed decoupling during deglaciation of the area.

Enteric bacterial pathogen detection in southern sea otters (Enhydra lutris nereis) is associated with coastal urbanization and freshwater runoff

PubMed Central

Miller, Melissa A.; Byrne, Barbara A.; Jang, Spencer S.; Dodd, Erin M.; Dorfmeier, Elene; Harris, Michael D.; Ames, Jack; Paradies, David; Worcester, Karen; Jessup, David A.; Miller, Woutrina A.

2009-01-01

Although protected for nearly a century, California’s sea otters have been slow to recover, in part due to exposure to fecally-associated protozoal pathogens like Toxoplasma gondii and Sarcocystis neurona. However, potential impacts from exposure to fecal bacteria have not been systematically explored. Using selective media, we examined feces from live and dead sea otters from California for specific enteric bacterial pathogens (Campylobacter, Salmonella, Clostridium perfringens, C. difficile and Escherichia coli O157:H7), and pathogens endemic to the marine environment (Vibrio cholerae, V. parahaemolyticus and Plesiomonas shigelloides). We evaluated statistical associations between detection of these pathogens in otter feces and demographic or environmental risk factors for otter exposure, and found that dead otters were more likely to test positive for C. perfringens, Campylobacter and V. parahaemolyticus than were live otters. Otters from more urbanized coastlines and areas with high freshwater runoff (near outflows of rivers or streams) were more likely to test positive for one or more of these bacterial pathogens. Other risk factors for bacterial detection in otters included male gender and fecal samples collected during the rainy season when surface runoff is maximal. Similar risk factors were reported in prior studies of pathogen exposure for California otters and their invertebrate prey, suggesting that land-sea transfer and/or facilitation of pathogen survival in degraded coastal marine habitat may be impacting sea otter recovery. Because otters and humans share many of the same foods, our findings may also have implications for human health. PMID:19720009

Ontogenetic dynamics of mercury accumulation in Northwest Atlantic sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Drevnick, P.E.; Horgan, M.J.; Oris, J.T.; Kynard, B.E.

2006-01-01

We examined the ontogenetic dynamics of mercury accumulation in sea lamprey (Petromyzon marinus) from the Connecticut River, USA. Mercury concentrations in eggs (mean 84 ng??g-1 wet weight) were lowest of all life stages and correlated to concentrations in females. There was a higher rate of maternal transfer of mercury to eggs compared with teleosts. Ammocoetes had high mercury concentrations for their trophic level (e.g., mean of age-4 ammocoetes 492 ng??g-1 wet weight). A further investigation of four streams showed that ammocoetes reflected the level of contamination in their nursery streams. Concentrations of mercury decreased during metamorphosis from ammocoete to adult. Mercury concentrations in adults ranged from 83 to 942 ng??g-1 wet weight and, unlike teleosts, showed no relation to sex, length, or weight. We provide evidence from stable isotope analyses that this high variability is due to feeding ecology. There are fundamental differences in mercury accumulation between sea lamprey and teleosts. ?? 2006 NRC Canada.

Discharge of New Subglacial Lake on Whillians Ice Stream: Implication for Ice Stream Flow Dynamics.

NASA Astrophysics Data System (ADS)

Sergienko, O. V.; Fricker, H. A.; Bindschadler, R. A.; Vornberger, P. L.; Macayeal, D. R.

2006-12-01

One of the surprise discoveries made possible by the ICESat laser altimeter mission of 2004-2006 is the presence of a large subglacial lake below the grounding zone of Whillians Ice Stream (dubbed here `Lake Helen' after the discoverer, Helen Fricker). What is even more surprising is the fact that this lake discharged a substantial portion of its volume during the ICESat mission, and changes in lake volume and surface elevation of the ice stream are documented in exquisite detail [Fricker et al., in press]. The presence and apparent dynamism of large subglacial lakes in the grounding zone of a major ice stream raises questions about their effects on ice-stream dynamics. Being liquid and movable, water modifies basal friction spatially and temporally. Melting due to shear heating and geothermal flux reduces basal traction, making the ice stream move fast. However, when water collects in a depression to form a lake, it potentially deprives the surrounding bed of lubricating water, and additionally makes the ice surface flat, thereby locally decreasing the ice stream driving stress. We study the effect of formation and discharge of a subglacial lake at the mouth of and ice stream using a two dimensional, vertically integrated, ice-stream model. The model is forced by the basal friction, ice thickness and surface elevation. The basal friction is obtained by inversion of the ice surface velocity, ice thickness and surface elevation come from observations. To simulate the lake formation we introduce zero basal friction and "inflate" the basal elevation of the ice stream at the site of the lake. Sensitivity studies of the response of the surrounding ice stream and ice shelf flow are performed to delineate the influence of near-grounding-line subglacial water storage for ice streams in general.

Modulations of aerosol impacts on cloud microphysics induced by the warm Kuroshio Current under the East Asian winter monsoon

NASA Astrophysics Data System (ADS)

Koike, M.; Asano, N.; Nakamura, H.; Sakai, S.; Nagao, T. M.; Nakajima, T. Y.

2016-10-01

In our previous aircraft observations, the possible influence of high sea surface temperature (SST) along the Kuroshio Current on aerosol-cloud interactions over the western North Pacific was revealed. The cloud droplet number concentration (Nc) was found to increase with decreasing near-surface static stability (NSS), which was evaluated locally as the difference between the SST and surface air temperature (SAT). To explore the spatial and temporal extent to which this warm SST influence can be operative, the present study analyzed Nc values estimated from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite measurements. The comparison of the local Nc values between the high and low SST - SAT days revealed a marked increase in Nc (up to a factor of 1.8) along the Kuroshio Current in the southern East China Sea, where particularly high SST - SAT values (up to 8 K) were observed in winter under monsoonal cold air outflows from the Asian Continent. This cold airflow destabilizes the atmospheric boundary layer, which leads to enhanced updraft velocities within the well-developed mixed layer and thus greater Nc. The monsoonal northwesterlies also bring a large amount of anthropogenic aerosols from the Asian continent that increase Nc in the first place. These results suggest that the same modulations of cloud microphysics can occur over other warm western boundary currents, including the Gulf Stream, under polluted cool continental airflows. Possibilities of influencing the cloud liquid water path are also discussed.

Societal Benefits of Ocean Altimetry Data

NASA Astrophysics Data System (ADS)

Srinivasan, M.; Leben, R.

2006-07-01

The NASA/CNES Jason satellite, follow-on to the highly successful TOPEX/Poseidon mission, continues to provide oceanographers and marine operators across the globe with a continuous thirteen-year, high-quality stream of sea surface height data. The mission is expected to extend through 2008, when the NASA/NOAA/CNES follow-on mission, the ocean surface topography mission, will be launched. This unprecedented resource of valuable ocean data is being used to map sea surface height, geostrophic velocity, significant wave height, and wind speed over the global oceans. Altimeter data products are currently used by hundreds of researchers and operational users to monitor ocean circulation and improve our understanding of the role of the oceans in climate and weather. Ocean altimeter data have many societal benefits and have proven invaluable in many practical applications including; -Climate research and forecasting -Hurricane forecasting and tracking -Ocean forecasting systems -Ship routing and marine operations -Marine mammal habitat monitoring -Education The data have been cited in over 2,100 research and popular articles since the launch of TOPEX/Poseidon in 1992, and almost 200 scientific users receive the global coverage altimeter data on a monthly basis. In addition to the scientific and operational uses of the data, the educational community has seized the unique concepts highlighted by these altimeter missions as a resource for teaching ocean science to students from grade school through college. This presentation will highlight new societal benefits of ocean altimetry data in the areas of climate studies, marine operations, marine research, and non-ocean investigations.

Chemosterilization of the sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Hanson, Lee H.; Manion, Patrick J.

1978-01-01

The chemical, P,P-bis(1-aziridinyl)-N-methylphosphinothioic amide (bisazir), was found in laboratory studies to be an effective sterilant for both sexes of adult sea lampreys (Petromyzon marinus) when given intraperitoneally at a dosage of 100 mg per kilogram of body weight. A total of 300 normal spawning-run sea lampreys and 300 injected with bisazir were released into the Big Garlic River, Marquette County, Michigan, (a small stream divided into five sections by natural barriers), to determine the effect of bisazir on the nesting and spawning behavior of the adults and on the production of larvae. The lampreys constructed and spawned in 95 nests. Sterile adults showed no abnormal nest building or spawning behavior. Sterile males competed effectively with normal males for females. Egg samples taken from nests indicated that eggs in nests where sterile males spawned with sterile or normal females did not hatch, although some embryonic development occurred. Extensive surveys with electric shockers produced no larvae in stream sections where sterile males spawned, but yielded numerous larvae in sections where normal males spawned with normal females. These findings suggest that the release of sterile males may be an effective tool in an integrated approach to control of sea lampreys in the Great Lakes.

Geophysical Global Modeling for Extreme Crop Production Using Photosynthesis Models Coupled to Ocean SST Dipoles

NASA Astrophysics Data System (ADS)

Kaneko, D.

2016-12-01

Climate change appears to have manifested itself along with abnormal meteorological disasters. Instability caused by drought and flood disasters is producing poor harvests because of poor photosynthesis and pollination. Fluctuations of extreme phenomena are increasing rapidly because amplitudes of change are much greater than average trends. A fundamental cause of these phenomena derives from increased stored energy inside ocean waters. Geophysical and biochemical modeling of crop production can elucidate complex mechanisms under seasonal climate anomalies. The models have progressed through their combination with global climate reanalysis, environmental satellite data, and harvest data on the ground. This study examined adaptation of crop production to advancing abnormal phenomena related to global climate change. Global environmental surface conditions, i.e., vegetation, surface air temperature, and sea surface temperature observed by satellites, enable global modeling of crop production and monitoring. Basic streams of the concepts of modeling rely upon continental energy flow and carbon circulation among crop vegetation, land surface atmosphere combining energy advection from ocean surface anomalies. Global environmental surface conditions, e.g., vegetation, surface air temperature, and sea surface temperature observed by satellites, enable global modeling of crop production and monitoring. The method of validating the modeling relies upon carbon partitioning in biomass and grains through carbon flow by photosynthesis using carbon dioxide unit in photosynthesis. Results of computations done for this study show global distributions of actual evaporation, stomata opening, and photosynthesis, presenting mechanisms related to advection effects from SST anomalies in the Pacific, Atlantic, and Indian oceans on global and continental croplands. For North America, climate effects appear clearly in severe atmospheric phenomena, which have caused drought and forest fires through seasonal advection thermal effects on potential evaporation by winds blowing eastward over California, the Grand Canyon, Monument Valley, and into the Great Plains. These coupled SST photosynthesis models constitute an advanced approach for crop modeling in the era of recent new climate.

Insights into Spatial Sensitivities of Ice Mass Response to Environmental Change from the SeaRISE Ice Sheet Modeling Project I: Antarctica

NASA Technical Reports Server (NTRS)

Nowicki, Sophie; Bindschadler, Robert A.; Abe-Ouchi, Ayako; Aschwanden, Andy; Bueler, Ed; Choi, Hyengu; Fastook, Jim; Granzow, Glen; Greve, Ralf; Gutowski, Gail;

Application of a putative alarm cue hastens the arrival of invasive sea lamprey (Petromyzon marinus) at a trapping location

USGS Publications Warehouse

Hume, John B.; Meckley, Trevor D.; Johnson, Nicholas; Luhring, Thomas M; Siefkes, Michael J; Wagner, C. Michael

2015-01-01

The sea lamprey Petromyzon marinus is an invasive pest in the Laurentian Great Lakes basin, threatening the persistence of important commercial and recreational fisheries. There is substantial interest in developing effective trapping practices via the application of behavior-modifying semiochemicals (odors). Here we report on the effectiveness of utilizing repellent and attractant odors in a push–pull configuration, commonly employed to tackle invertebrate pests, to improve trapping efficacy at permanent barriers to sea lamprey migration. When a half-stream channel was activated by a naturally derived repellent odor (a putative alarm cue), we found that sea lamprey located a trap entrance significantly faster than when no odor was present as a result of their redistribution within the stream. The presence of a partial sex pheromone, acting as an attractant within the trap, was not found to further decrease the time to when sea lamprey located a trap entrance relative to when the alarm cue alone was applied. Neither the application of alarm cue singly nor alarm cue and partial sex pheromone in combination was found to improve the numbers of sea lamprey captured in the trap versus when no odor was present — likely because nominal capture rate during control trials was unusually high during the study period. Behavioural guidance using these odors has the potential to both improve control of invasive non-native sea lamprey in the Great Lakes as well as improving the efficiency of fish passage devices used in the restoration of threatened lamprey species elsewhere.

El-Niño/Southern Oscillation (ENSO) influences on monthly NO 3 load and concentration, stream flow and precipitation in the Little River Watershed, Tifton, Georgia (GA)

NASA Astrophysics Data System (ADS)

Keener, V. W.; Feyereisen, G. W.; Lall, U.; Jones, J. W.; Bosch, D. D.; Lowrance, R.

2010-02-01

SummaryAs climate variability increases, it is becoming increasingly critical to find predictable patterns that can still be identified despite overall uncertainty. The El-Niño/Southern Oscillation is the best known pattern. Its global effects on weather, hydrology, ecology and human health have been well documented. Climate variability manifested through ENSO has strong effects in the southeast United States, seen in precipitation and stream flow data. However, climate variability may also affect water quality in nutrient concentrations and loads, and have impacts on ecosystems, health, and food availability in the southeast. In this research, we establish a teleconnection between ENSO and the Little River Watershed (LRW), GA., as seen in a shared 3-7 year mode of variability for precipitation, stream flow, and nutrient load time series. Univariate wavelet analysis of the NINO 3.4 index of sea surface temperature (SST) and of precipitation, stream flow, NO 3 concentration and load time series from the watershed was used to identify common signals. Shared 3-7 year modes of variability were seen in all variables, most strongly in precipitation, stream flow and nutrient load in strong El Niño years. The significance of shared 3-7 year periodicity over red noise with 95% confidence in SST and precipitation, stream flow, and NO 3 load time series was confirmed through cross-wavelet and wavelet-coherence transforms, in which common high power and co-variance were computed for each set of data. The strongest 3-7 year shared power was seen in SST and stream flow data, while the strongest co-variance was seen in SST and NO 3 load data. The strongest cross-correlation was seen as a positive value between the NINO 3.4 and NO 3 load with a three-month lag. The teleconnection seen in the LRW between the NINO 3.4 index and precipitation, stream flow, and NO 3 load can be utilized in a model to predict monthly nutrient loads based on short-term climate variability, facilitating management in high risk seasons.

Seafloor Morphology And Sediment Discharge Of The Storfjorden And Kveithola Palaeo-Ice Streams (NW Barents Sea) During The Last Deglaciation

NASA Astrophysics Data System (ADS)

Camerlenghi, Angelo; Rebesco, Michele; Pedrosa, Mayte; Demol, Ben; Giulia Lucchi, Renata; Urgeles, Roger; Colmenero-Hidalgo, Elena; Andreassen, Karin; Sverre Laberg, Jan; Winsborrow, Monica

2010-05-01

IPY Activity N. 367 focusing on Neogene ice streams and sedimentary processes on high- latitude continental margins (NICE-STREAMS) resulted in two coordinated cruises on the adjacent Storfjorden and Kveithola trough-mouth fans in the NW Barents Sea: SVAIS Cruise of BIO Hespérides, summer 2007, and EGLACOM Cruise of Cruise R/V OGS-Explora, summer 2008. The objectives were to acquire a high-resolution set of bathymetric, seismic and sediment core data in order to decipher the Neogene architectural development of the glacially-dominated NW Barents Sea continental margin in response to natural climate change. The paleo-ice streams drained ice from southern Spitsbergen, Spitsbergen Bank, and Bear Island. The short distance from the ice source to the calving front produced a short residence time of ice, and therefore a rapid response to climatic changes. In the outer trough of southern Storfjorden, lobate moraines superimpose and are cut by very large linear features attributed to mega-iceberg scours. In the adjacent Kveithola trough, a fresh morphology includes mega-scale glacial lineations overprinted by transverse grounding-zone wedges, diagnostic of episodic ice stream retreat. A 15 m thick glacimarine drape suggests an high post-deglaciation sedimentation rate. Preliminary interpretation suggests that the retreat of the Svalbard/Barents Sea Ice Sheet was highly dynamic and that grounded ice persisted on Spitsbergen Bank for some thousands years after the main Barents Sea deglaciation.The Storfjorden continental slope is divided into three wide lobes. Opposite the two northernmost lobes the slope is dominated by straight gullies in the upper part, and deposition of debris lobes on the mid and lower parts. In contrast, the southernmost lobe is characterized by widespread occurrence of submarine landslides. Sediment failure has accompanied the evolution of the southern Storfjorden and Kveithola margin throughout the Late Neogene, with very large mass transport deposits up to 200 m thick in the early phases of the development of the glacially influenced margin. Conversely, the central and northern parts of the Storfjorden margin have prograded without appreciable episodes of mass failure. Sedimentation has occurred through alternate layering of decimeter-thick glacial debris flows deposits, with laminated and acoustically transparent interglacial sediment drape. Gullies and paleo-gullies incise the glacial debris flows and are covered by the interglacial drape. They are formed early during each deglaciation phase, most likely by the erosive action of short-lived hyperpycnal flows generated by sediment-laden subglacial meltwater discharge. In sediment cores thick finely-laminated sedimentary beds on the upper continental slope of the southern part of the margin indicate preferential deposition by settlement of meltwater sediment plumes. High sedimentation rates of plumites may contribute to the slope instability and suggest that meltwater discharge was focused on the southern Storfjorden and Kveithola paleo-ice streams.

Rate and style of ice stream retreat constrained by new surface-exposure ages: The Minch, NW Scotland

NASA Astrophysics Data System (ADS)

Bradwell, Tom; Small, David; Fabel, Derek; Dove, Dayton; Cofaigh, Colm O.; Clark, Chris; Consortium, Britice-Chrono

2016-04-01

Chronologically constrained studies of former ice-sheet extents and dynamics are important for understanding past cryospheric responses and modelling future ice-sheet and sea-level change. As part of the BRITICE-CHRONO project, we present new geomorphological and chronological data from a marine-terminating ice stream system in NW Europe that operated during the Late Weichselian Glaciation. A suite of 51 cosmogenic-nuclide exposure ages from ice sheet moraines and glacially transported boulders constrain the maximum extent of the ice sheet on the continental shelf (~28 ka BP) and its subsequent retreat, between ~27 and 16 ka BP, into a large marine embayment (ca. 7000 km2; the Minch, NW Scotland). Recently acquired swath bathymetry and acoustic sub-bottom profiler data reveal several large transverse grounding-zone wedges up to 40 m thick and 5 km wide with diagnostic acoustic-facies architecture. These seabed sediment wedges mark former quasi-stable positions of grounded marine-terminating ice-stream fronts; their size and thickness suggest long-lived stillstands of the order of centuries. Statistically significant clusters of exposure ages from glacial deposits on islands and intervening headlands shed important new light on the age of these marine grounding-zone wedges and, by inference, the rate and timing of Minch palaeo-ice stream retreat. We find strong evidence for episodic ice stream retreat on the continental shelf between ~28-24 ka BP, in the outer Minch between ~24-22 ka BP, and in the central Minch between 22-18.5 ka BP. In contrast, final ice stream deglaciation (<18 ka) across the deepest parts of the inner Minch embayment, was probably rapid and uninterrupted - with the ice sheet margin at or close to the present-day coastline in NW Scotland by 16.1 ka BP. It is hoped that these results will form the empirical basis for future ice-sheet modelling of this dynamically sensitive sector of the British-Irish Ice Sheet.

A Comparison of Streaming and Microelectrophoresis Methods for Obtaining the zeta Potential of Granular Porous Media Surfaces.

PubMed

Johnson

1999-01-01

The electrokinetic behavior of granular quartz sand in aqueous solution is investigated by both microelectrophoresis and streaming potential methods. zeta potentials of surfaces composed of granular quartz obtained via streaming potential methods are compared to electrophoretic mobility zeta potential values of colloid-sized quartz fragments. The zeta values generated by these alternate methods are in close agreement over a wide pH range and electrolyte concentrations spanning several orders of magnitude. Streaming measurements performed on chemically heterogeneous mixtures of physically homogeneous sand are shown to obey a simple mixing model based on the surface area-weighted average of the streaming potentials associated with the individual end members. These experimental results support the applicability of the streaming potential method as a means of determining the zeta potential of granular porous media surfaces. Copyright 1999 Academic Press.

Water Resources Data, Florida, Water Year 2003 Volume 2A: South Florida Surface Water

USGS Publications Warehouse

Price, C.; Woolverton, J.; Overton, K.

2004-01-01

Water resources data for 2003 water year in Florida consists of continuous or daily discharge for 385 streams, periodic discharge for 13 streams, continuous or daily stage for 255 streams, periodic stage for 13 stream, peak discharge for 36 streams, and peak stage for 36 streams, continuous or daily elevations for 13 lakes, periodic elevations for 46 lakes, continuous ground-water levels for 441 wells, periodic ground-water levels for 1227 wells, quality of water data for 133 surface-water sites, and 308 wells. The data for South Florida included continuous or daily discharge for 72 streams, continuous or daily stage for 50 streams, no peak stage discharge for streams, 1 continuous elevation for lake, continuous ground-water levels for 237 wells, periodic ground-water levels for 248 wells, water quality for 25 surface-water sites, and 161 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperation with local, state, and federal agencies in Florida.

Water Resources Data, Florida, Water Year 2003, Volume 3A: Southwest Florida Surface Water

USGS Publications Warehouse

Kane, R.L.; Fletcher, W.L.

2004-01-01

Water resources data for the 2003 water year in Florida consist of continuous or daily discharges for 385 streams, periodic discharge for 13 streams, continuous daily stage for 255 streams, periodic stage for 13 streams, peak stage for 36 streams and peak discharge for 36 streams, continuous or daily elevations for 13 lakes, periodic elevations for 46 lakes; continuous ground-water levels for 441 wells, periodic ground-water levels for 1,227 wells, and quality-of-water data for 133 surface-water sites and 308 wells. The data for Southwest Florida include records of stage, discharge, and water quality of streams; stage, contents, water quality of lakes and reservoirs, and water levels and water quality of ground-water wells. Volume 3A contains continuous or daily discharge for 103 streams, periodic discharge for 7 streams, continuous or daily stage for 67 streams, periodic stage for 13 streams, peak stage and discharge for 8 streams, continuous or daily elevations for 2 lakes, periodic elevations for 26 lakes, and quality-of-water data for 62 surface-water sites. These data represent the national Water Data System records collected by the U.S. Geological Survey and cooperating local, state, and federal agencies in Florida.

Fully reprocessed ERS-1 altimeter data from 1992 to 1995: Feasibility of the detection of long term sea level change

NASA Astrophysics Data System (ADS)

Anzenhofer, M.; Gruber, T.

1998-04-01

Global mean sea level observations are necessary to answer the urgent questions about climate changes and their impact on socio-economy. At GeoForschungsZentrum/Geman Processing and Archiving Facility ERS altimeter data is used to systematically generate geophysical products such as sea surface topography, high-resolution geoid and short- and long-period sea surface height models. On the basis of this experience, fully reprocessed ERS-1 altimeter data is used to generated a time series of monthly sea surface height models from April 1992 to April 1995. The reprocessing consists of improved satellite ephemerides, merging of Grenoble tidal model, and application of range corrections due to timing errors. With the new data set the TOPEX/POSEIDON prelaunch accuracy requirements are fulfilled. The 3-year time series is taken to estimate the rate of change of global mean sea level. A careful treatment of seasonal effects is considered. A masking of continents, sea ice, and suspect sea surface heights is chosen that is common for all sea surface height models. The obtained rate of change is compared to external results from tide gauge records and TOPEX/POSEIDON data. The relation of sea level changes and sea surface temperature variations is examined by means of global monthly sea surface temperature maps. Both global wind speed and wave height maps are investigated and correlated with sea surface heights and sea surface temperatures in order to find other indicators of climate variations. The obtained rate of changes of the various global maps is compared to an atmospheric CO2 anomaly record, which is highly correlated to El Niño events. The relatively short period of 3 years, however, does not allow definite conclusions with respect to possible long-term climate changes.

36 year trends in dissolved organic carbon export from Finnish rivers to the Baltic Sea.

PubMed

Räike, Antti; Kortelainen, Pirkko; Mattsson, Tuija; Thomas, David N

2012-10-01

Increasing dissolved organic carbon (DOC) concentrations in lakes, rivers and streams in northern mid latitudes have been widely reported during the last two decades, but relatively few studies have dealt with trends in DOC export. We studied the export of DOC from Finnish rivers to the Baltic Sea between 1975 and 2010, and estimated trends in DOC fluxes (both flow normalised and non-normalised). The study encompassed the whole Finnish Baltic Sea catchment area (301,000 km(2)) covering major land use patterns in the boreal zone. Finnish rivers exported annually over 900,000 t DOC to the Baltic Sea, and the mean area specific export was 3.5 t km(-2). The highest export (7.3t km(-2)) was measured in peat dominated catchments, whereas catchments rich in lakes had the lowest export (2.2 t km(-2)). Inter-annual variation in DOC export was high and controlled mainly by hydrology. There was no overall trend in the annual water flow, although winter flow increased in northern Finland over 36 years. Despite the numerous studies showing increases in DOC concentrations in streams and rivers in the northern hemisphere, we could not find any evidence of increases in DOC export to the northern Baltic Sea from Finnish catchments since 1975. Copyright © 2012 Elsevier B.V. All rights reserved.

Long-Term Controls on Solute and Sediment Fluxes From a Rapidly Weathering Tropical Watershed

NASA Astrophysics Data System (ADS)

Shanley, J. B.; McDowell, W. H.; Stallard, R. F.

2006-12-01

The 326-ha Rio Icacos watershed in the tropical wet forest of the Luquillo Mountains, northeastern Puerto Rico, is underlain by granodiorite bedrock with weathering rates among the highest in the world. We pooled stream chemistry and suspended sediment datasets from three discrete periods: 1983-87; 1991-97; and 2000-05, which bracket two major hurricanes that crossed the site; Hugo in 1988 and Georges in 1998. This mountainous landscape is also subject to frequent disturbance by landslides. Stream major ion chemistry reflects weathering of the granodiorite, but dilutes by as much as 90% during the largest storms. This dilution reflects the increasing dominance of rainwater (and cloud water) with increasing streamflow, as major ion stoichiometry is maintained except when precipitation is high in sea salt. Given the broad area of surface saturation, low-permeability soils, and flashy stream hydrograph which quickly returns to base flow, it appears that precipitation moves to the stream by saturation overland flow. Piping and rapid shallow subsurface flow through the rooting zone may also facilitate precipitation movement off hillslopes. Concentration-discharge relations for most major ions were fairly stable through time, suggesting minimal long-term effects from disturbance. The exception was nitrate, which increased from near 5 μmol L-1 during the 1983-87 period to greater than 12 μmol L-1 and remaining elevated for several years following each of the two hurricanes. The relation between suspended sediment concentration and discharge was also stable over time but exhibited more variability, some due to hysteresis but some likely caused by pulsed sediment from discrete disturbances.

Insights into the Geographic Sequence of Deglaciation in the Weddell Sea Embayment by Provenance of Ice-Rafted Debris

NASA Astrophysics Data System (ADS)

Williams, T.; Hemming, S. R.; Licht, K.; Agrios, L.; Brachfeld, S. A.; van de Flierdt, T.; Hillenbrand, C. D.; Ehrmann, W. U.; Zhai, X.; Cai, Y.; Corley, A. D.; Kuhn, G.

2017-12-01

The geochemical and geochronological fingerprint of rock debris eroded and carried by ice streams may be used to identify the provenance of iceberg-rafted debris (IRD) in the marine sediment record. During ice retreat following glacial maxima, it has been shown that there is an increase in IRD accumulation in marine sediments underlying the western limb of the Weddell Gyre. Here we present IRD provenance records from sediment core PS1571-1 in the NW Weddell Sea, and interpret these records in terms of the geographic sequence of ice sheet retreat in the Weddell Sea embayment during the most recent deglaciation. We first characterize the source areas of eroded debris around the Weddell Sea Embayment, using published mapping of the embayment and new material from: 1. Till in modern moraines at the edges of ice streams, including the Foundation Ice Stream, the Academy Glacier, and the Recovery Glacier; and 2. Subglacial till and proximal glaciomarine sediment from existing cores located along the front of the Filchner and Ronne Ice Shelves, collected on past expeditions of the RV Polarstern. The analyses on these samples include 40Ar/39Ar hornblende and biotite thermochronology and U-Pb zircon geochronology on individual mineral grains, and K-Ar thermochronology, Nd isotopes, and clay mineralogy on the clay grain size fraction. Results so far indicate that samples along the front of the Filchner and Ronne Ice Shelves record the geochemical and geochronological fingerprint that would be expected from tracing ice flow lines back to the bedrock terranes. The Ronne (west), Hughes (central), and Filchner (east) sectors have distinguishable provenance source signatures, and further subdivision is possible. In core PS1571-1, downcore IRD provenance changes reflect iceberg output and ice sheet retreat from the different sectors of the embayment through the last deglaciation. The detrital provenance method of interpreting the geographic sequence of ice retreat can equally be applied to previous deglaciations of the Weddell Sea Embayment.

An analysis of the synoptic and dynamical characteristics of hurricane Sandy (2012)

NASA Astrophysics Data System (ADS)

Varlas, George; Papadopoulos, Anastasios; Katsafados, Petros

2018-01-01

Hurricane Sandy affected the Caribbean Islands and the Northeastern United States in October 2012 and caused 233 fatalities, severe rainfalls, floods, electricity blackouts, and 75 billion U.S. dollars in damages. In this study, the synoptic and dynamical characteristics that led to the formation of the hurricane are investigated. The system was driven by the interaction between the polar jet displacement and the subtropical jet stream. In particular, Sandy was initially formed as a tropical depression system over the Caribbean Sea and the unusually warm sea drove its intensification. The interaction between a rapidly approaching trough from the northwest and the stagnant ridge over the Atlantic Ocean drove Sandy to the northeast coast of United States. To better understand the dynamical characteristics and the mechanisms that triggered Sandy, a non-hydrostatic mesoscale model has been used. Model results indicate that the surface heat fluxes and the moisture advection enhanced the convective available potential energy, increased the low-level convective instability, and finally deepened the hurricane. Moreover, the upper air conditions triggered the low-level frontogenesis and increased the asymmetry of the system which finally affected its trajectory.

Coralline alga reveals first marine record of subarctic North Pacific climate change

USGS Publications Warehouse

Halfar, J.; Steneck, R.; Schone, B.; Moore, G.W.K.; Joachimski, M.; Kronz, A.; Fietzke, J.; Estes, James A.

2007-01-01

While recent changes in subarctic North Pacific climate had dramatic effects on ecosystems and fishery yields, past climate dynamics and teleconnection patterns are poorly understood due to the absence of century-long high-resolution marine records. We present the first 117-year long annually resolved marine climate history from the western Bering Sea/Aleutian Island region using information contained in the calcitic skeleton of the long-lived crustose coralline red alga Clathromorphum nereostratum, a previously unused climate archive. The skeletal ??18O-time series indicates significant warming and/or freshening of surface waters after the middle of the 20th century. Furthermore, the time series is spatiotemporally correlated with Pacific Decadal Oscillation (PDO) and tropical El Nio??-Southern Oscillation (ENSO) indices. Even though the western Bering Sea/Aleutian Island region is believed to be outside the area of significant marine response to ENSO, we propose that an ENSO signal is transmitted via the Alaskan Stream from the Eastern North Pacific, a region of known ENSO teleconnections. Copyright 2007 by the American Geophysical Union.

Water Resources Data, Florida, Water Year 2003, Volume 1A: Northeast Florida Surface Water

USGS Publications Warehouse

,

2004-01-01

Water resources data for the 2003 water year in Florida consist of continuous or daily discharge for 385 streams, periodic discharge for 13 streams, continuous or daily stage for 255 streams, periodic stage for 13 streams, peak stage and discharge for 36 streams; continuous or daily elevations for 13 lakes, periodic elevations for 46 lakes; continuous ground-water levels for 441 wells, periodic ground-water levels for 1,227 wells; quality-of-water data for 133 surface-water sites and 308 wells. The data for northeast Florida include continuous or daily discharge for 138 streams, periodic discharge for 3 streams, continuous or daily stage for 61 streams, periodic stage for 0 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 9 lakes, periodic elevations for 20 lakes; continuous ground water levels for 73 wells, periodic groundwater levels for 543 wells; quality-of-water data for 43 surface-water sites and 115 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

The Effect of Waves on the Tidal-Stream Energy Resource

NASA Astrophysics Data System (ADS)

Lewis, M. J.; Neill, S. P.; Robins, P. E.; Hashemi, M. R.

2016-02-01

The tidal-stream energy resource is typically estimated using depth-averaged "tide-only" hydrodynamic models and do not consider the influence of waves. We find that waves will reduce the available resource, and the wave climate needs to be considered when designing a resilient and efficient tidal-stream energy device. Using well-validated oceanographic models of the Irish Sea and Northwest European shelf, we show tidal-stream energy sites with quiescent wave climates are extremely limited, with limited sea-space and limited scope for future development. To fully realise the potential of tidal-stream energy and to ensure globally deployable devices, the influence of waves on the resource and turbines must be considered. The effect of waves upon the tidal current was investigated using observations (ADCP and wave buoy time-series), and a state-of-the-art, 3-dimensional, dynamically coupled wave-tide model (COAWST). The presence of waves reduced the depth-averaged tidal current, which reduced the potential extractable power by 10% per metre wave height increase. To ensure resilience and survivability, tidal-stream energy device may cease to produce electricity during extremes (often called downtime), however the wave conditions threshold for device shut-down is unknown, and requires future work. The presence of waves will also effect turbine performance and design criteria; for example, the presence of waves was found to alter the shape of the velocity profile, and wave-current misalignment (waves propagating at an angle oblique to the plane of tidal flow) was found to occur for a significant amount of time at many potential tidal-stream energy sites. Therefore, waves reduced the available resource, furthermore the influence of waves on the interaction between tidal energy devices and the tidal-stream resource needs to be characterised in physically-scaled tank experiments and computational fluid dynamics (CFD) numerical models.

Dry Stream Reaches in Carbonate Terranes: Surface Indicators of Ground-Water Reservoirs

USGS Publications Warehouse

Brahana, J.V.; Hollyday, E.F.

1988-01-01

In areas where dry stream reaches occur, subsurface drainage successfully competes with surface drainage, and sheet-like dissolution openings have developed parallel to bedding creating the ground-water reservoir. Union Hollow in south-central Tennessee is the setting for a case study that illustrates the application of the dry stream reach technique. In this technique, dry stream reach identification is based on two types of readily acquired information: remotely sensed black and white infrared aerial photography; and surface reconnaissance of stream channel characteristics. Test drilling in Union Hollow subsequent to identification of the dry reach proved that a localized ground-water reservoir was present.

Key roles of sea ice in inducing contrasting modes of glacial AMOC and climate

NASA Astrophysics Data System (ADS)

Sherriff-Tadano, S.; Abe-Ouchi, A.

2017-12-01

Gaining a better understanding of glacial Atlantic meridional overturning circulation (AMOC) is important to interpret the glacial climate changes such as the Heinrich event. Recent studies suggest that changes in sea ice over the North Atlantic largely affect the surface wind. Since changes in surface wind have a large impact on the AMOC, this implies a role of sea ice in modifying the AMOC though surface wind. However, the impact of sea ice on the surface winds and the impact of changes in the winds on the AMOC remain unclear. In this study, we first assess the impact of sea ice expansion on the winds. We then explore whether the changes in winds play a role in modifying the AMOC and climate. For this purpose, results from MIROC4m are analyzed (Kawamura et al. 2017). To clarify the impact of changes in sea ice on the surface wind, sensitivity experiments are conducted with an atmospheric general circulation model (AGCM). In the AGCM experiments, we modify the sea ice to extract the impact of sea ice on the winds. Partial decouple experiments are conducted with the coupled model MIROC4m, which we modify the surface winds to assess the impact of changes in the surface wind due to sea ice expansion on the AMOC. Results show that expansion of sea ice substantially weakens the surface wind over the northern North Atlantic. AGCM experiments show that a drastic decrease in surface temperature duo to a suppression of sensible heat flux plays a dominant role in weakening the surface winds through increasing the static stability of the air column near the surface. Partial decouple experiments with MIROC4m show that the weakening of the surface wind due to the expansion of sea ice plays an important role in maintaining the weak AMOC. Thus, these experiments show that the weakening of the surface winds due to sea ice expansion plays a role in stabilizing the AMOC.

In Situ Global Sea Surface Salinity and Variability from the NCEI Global Thermosalinograph Database

NASA Astrophysics Data System (ADS)

Wang, Z.; Boyer, T.; Zhang, H. M.

2017-12-01

Sea surface salinity (SSS) plays an important role in the global ocean circulations. The variations of sea surface salinity are key indicators of changes in air-sea water fluxes. Using nearly 30 years of in situ measurements of sea surface salinity from thermosalinographs, we will evaluate the variations of the sea surface salinity in the global ocean. The sea surface salinity data used are from our newly-developed NCEI Global Thermosalinograph Database - NCEI-TSG. This database provides a comprehensive set of quality-controlled in-situ sea-surface salinity and temperature measurements collected from over 340 vessels during the period 1989 to the present. The NCEI-TSG is the world's most complete TSG dataset, containing all data from the different TSG data assembly centers, e.g. COAPS (SAMOS), IODE (GOSUD) and AOML, with more historical data from NCEI's archive to be added. Using this unique dataset, we will investigate the spatial variations of the global SSS and its variability. Annual and interannual variability will also be studied at selected regions.

Water resources of the Port Madison Indian Reservation, Washington

USGS Publications Warehouse

Lum, W.E.

1979-01-01

The study summarized in this report was made to provide Suquamish Tribal leaders with information on the reservation 's surface- and ground-water resources. The Tribal leaders need this information to help manage and protect their water resources against over-development. The quantity of ground water estimated to be available for withdrawal on a long-term basis is about 600 million gallons per year in the western part of the reservation and 400 million gallons per year in the eastern part of the reservation. It should be possible, economically and practically, to capture at least 40 percent of this ground water with properly constructed and located wells before it is discharged into the sea. This is enough water to supply at least 5,000 and 3,500 people with domestic water in these respective areas--about four times the present population. Of nine stream sites that were studied, the lowest average streamflows for a 7-day period estimated to occur an average of once in 2 years were 1.3 cubic feet per second or less. Streams at three of the sites have been observed dry at least once. The short period of data collection during this study limits the accuracy of statistical estimates of low flows. Both surface and ground water are of good quality with no unusual or harmful constituents; there was no evidence of major pollution in 1977. In the future, seawater intrusion into the ground-water system and pollution of the surface water by improperly treated sewage waste water could become problems. (Woodard-USGS).

BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

USGS Publications Warehouse

Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

2014-01-01

BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

Simulation of laser beam reflection at the sea surface

NASA Astrophysics Data System (ADS)

Schwenger, Frédéric; Repasi, Endre

2011-05-01

A 3D simulation of the reflection of a Gaussian shaped laser beam on the dynamic sea surface is presented. The simulation is suitable for both the calculation of images of SWIR (short wave infrared) imaging sensor and for determination of total detected power of reflected laser light for a bistatic configuration of laser source and receiver at different atmospheric conditions. Our computer simulation comprises the 3D simulation of a maritime scene (open sea/clear sky) and the simulation of laser light reflected at the sea surface. The basic sea surface geometry is modeled by a composition of smooth wind driven gravity waves. The propagation model for water waves is applied for sea surface animation. To predict the view of a camera in the spectral band SWIR the sea surface radiance must be calculated. This is done by considering the emitted sea surface radiance and the reflected sky radiance, calculated by MODTRAN. Additionally, the radiances of laser light specularly reflected at the wind-roughened sea surface are modeled in the SWIR band considering an analytical statistical sea surface BRDF (bidirectional reflectance distribution function). This BRDF model considers the statistical slope statistics of waves and accounts for slope-shadowing of waves that especially occurs at flat incident angles of the laser beam and near horizontal detection angles of reflected irradiance at rough seas. Simulation results are presented showing the variation of the detected laser power dependent on the geometric configuration of laser, sensor and wind characteristics.

A Proton Flare Triggered the Mw 8.1 Chiapos Mexican Earthquake

NASA Astrophysics Data System (ADS)

Elfaki, H.; Yousef, S.

2017-12-01

In a 2015 Cairo University M.Sc. thesis by Sarah Khodairy, very strong earthquakes were found to be highly correlated with proton flares. Strange blue and green bright flashes of light across Mexico accompanied the 8th of September 2017 Mw 1.8 Chiapas earthquake. Those lights were contemporary with a solar proton flare. Those green and blue lights are indicative of the arrival of proton streams over Mexico and their interaction with atmospheric Oxygen and Nitrogen atoms respectively in analogy with aurora lights. The proton streams attacked the weak spots of tectonic plates where the Coscos plate is being subducted below the North American plate. It is suggested that they induced telluric electric currents in the ground and in the magma thus caused motion and more subduction in the tectonic plates. Such motion immediately trigged the Chiapas earthquake in the near vicinity. The Bz component of the interplanetary magnetic field was highly negative, a door was opened in the magnetosphere and the proton stream easily leaked inside and targeted Mexico. This proton flare was accompanied by coronal mass ejection and extremely strong X.9.3- class X-ray flare as well as magnetic storms. On the other hand, the 19th of September Mw 7.1 Puebla central Mexico earthquake was initiated by fast solar wind coronal hole stream. Such stream if they hit ground they cause earthquakes, if they hit narrow seas like the Red Sea they cause flash floods. However if they target Oceans they initiate hurricanes.

Research note: Mapping spatial patterns in sewer age, material, and proximity to surface waterways to infer sewer leakage hotspots

USGS Publications Warehouse

Hopkins, Kristina G.; Bain, Daniel J.

2018-01-01

Identifying areas where deteriorating sewer infrastructure is in close proximity to surface waterways is needed to map likely connections between sewers and streams. We present a method to estimate sewer installation year and deterioration status using historical maps of the sewer network, parcel-scale property assessment data, and pipe material. Areas where streams were likely buried into the sewer system were mapped by intersecting the historical stream network derived from a 10-m resolution digital elevation model with sewer pipe locations. Potential sewer leakage hotspots were mapped by identifying where aging sewer pipes are in close proximity (50-m) to surface waterways. Results from Pittsburgh, Pennsylvania (USA), indicated 41% of the historical stream length was lost or buried and the potential interface between sewers and streams is great. The co-location of aging sewer infrastructure (>75 years old) near stream channels suggests that 42% of existing streams are located in areas with a high potential for sewer leakage if sewer infrastructure fails. Mapping the sewer-stream interface provides an approach to better understand areas were failing sewers may contribute a disproportional amount of nutrients and other pathogens to surface waterways.

Volga shallow offing dynamics investigation based on space photography

NASA Astrophysics Data System (ADS)

Kovalev, E. E.

Volga mouth region is investigated much better, than sea mouths of other river in Russia. In spite of the fact, not enough attention was devoted to Volga shallow offing. Volga shallow offing covers area about 9,3 ths. sq. km and has great significance for Caspian sea fish industry, because environmental conditions of this region and neighboring shallows of Northern Caspian Sea are determinative for passage, spawning and young fish growth of valuable sorts of fish. Insufficient investigation of Volga shallow offing is caused as by difficulty of access to this region through small depths (1 - 2 m) and intensive vegetation, so by data deficiency. Data deficiency notably intensified during recent 10 - 15 years, when significant reduction of hydro-meteorological investigations in Volga mouth area occurred. Gradual accumulation of on-site data, development of new technologies of map material analysis and space photography data processing allows to expect new scientific and application results. The purpose of our investigation concludes in determination of space-time mechanism of hydro-meteorological processes in Volga shallow offing based on space photography materials. Main results of our investigation can be summarized in following basic statements: (1) The most efficient method of Volga shallow offing investigation appears to be combined application of space photography data and on-site materials. (2) Electronic atlas of Volga shallow offing photomaps for the period of 1975 to 1997 yrs. is created. (3) Maps of above-water flora of Volga shallow offing for 1975 and 1997 yrs are created. (4) Electronic atlas of streams in Volga shallow offing for the period of 1975 to 1997 yrs. is created. On basis of it four maps of drain streams at Volga shallow offing are created. (5) Landscape zoning of Volga shallow offing is made and most active and passive regions are determined depending on drain streams and water vegetation. (6) It is shown, that development of Volga shallow offing and delta determines by river runoff fluctuations and sea level. The influence of sea level on intensity of shallow offing processes development is explored. New information about river flow paths advancing into sea at the seacoast is obtained. Its determined, that most intensive delta flooding is possible at sea level (near Makhachkala) more than -27,4 m abs. (7) Recommendations for canals layout in Volga shallow offing are given. (9) Prognosis of future channel net in Volga shallow offing is made.

Stochastic ice stream dynamics

PubMed Central

Bertagni, Matteo Bernard; Ridolfi, Luca

2016-01-01

Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution. PMID:27457960

Modeling the Effects of Sea-Level Rise on Groundwater Levels in Coastal New Hampshire

NASA Astrophysics Data System (ADS)

Jacobs, J. M.; Knott, J. F.; Daniel, J.; Kirshen, P. H.

2017-12-01

Coastal communities with high population density and low topography are vulnerable from sea-level rise (SLR) caused by climate change. Groundwater in coastal communities will rise with sea level impacting water quality, the structural integrity of infrastructure, and natural ecosystem health. SLR-induced groundwater rise has been studied in areas of high aquifer transmissivity and in low-lying areas immediately along the coast. In this regional study, we investigate SLR-induced groundwater rise in a coastal area characterized by shallow unconsolidated deposits overlying fractured bedrock, typical of the glaciated northeast United States. MODFLOW, a numerical groundwater-flow model, is used with groundwater observations, lidar topography, surface-water hydrology, and groundwater withdrawals to investigate SLR-induced changes in groundwater levels and vadose-zone thickness in New Hampshire's Seacoast. The SLR groundwater signal is detected up to 5 km from the coast, more than 3 times farther inland than projected surface-water flooding associated with SLR. Relative groundwater rise ranges from 38 to 98% of SLR within 1 km of the shoreline and drops below 4% between 4 and 5 km from the coast. The largest magnitude of SLR-induced groundwater rise occurs in the marine and estuarine deposits and land areas with tidal water bodies on three sides. In contrast, groundwater rise is dampened near streams. Groundwater inundation caused by 2 m of SLR is projected to contribute 48% of the total land inundation area in the City of Portsmouth with consequences for built and natural resources. Freshwater wetlands are projected to expand 3% by year 2030 increasing to 25% by year 2100 coupled with water-depth increases. These results imply that underground infrastructure and natural resources in coastal communities will be impacted by rising groundwater much farther inland than previously thought when considering only surface-water flooding from SLR.

Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

PubMed

Ma, Xiaohui; Chang, Ping; Saravanan, R; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

2015-12-04

High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy-atmosphere interaction in forecast and climate models.

Spatial variability in the response of surface-water extent to climate extremes across the Prairie Pothole Region and adjacent Northern Prairie, United States

NASA Astrophysics Data System (ADS)

Vanderhoof, M.; Lane, C.; McManus, M.; Alexander, L. C.; Christensen, J.

2017-12-01

Surface-water extent, duration and movement will depend not only on climatic inputs but also the relative importance of different hydrologic pathways (e.g., surface storage, infiltration, evapotranspiration, stream outflows). We mapped surface-water extent from historic drought years to historic wet years spanning 1985 - 2015 across eleven Landsat path/rows representing the Prairie Pothole Region (PPR) and adjacent Northern Prairie of the United States. The PPR not only experienced a greater surface water extent under median conditions (2.6 times more) relative to the adjacent Northern Prairie, but showed a greater difference between drought and deluge conditions as well (range averaged 8.5 ha surface water km-2 relative to 2.5 ha surface water km-2 for the PPR and Northern Prairie, respectively). To explain the spatial variability in the amount of surface water expansion and contraction we used a two-stage modeling approach. First, surface-water extent was regressed on accumulated water availability (precipitation minus potential evapotranspiration). The slope of surface-water extent to climate inputs (per watershed) was our dependent variable in the second stage. That slope was regressed against independent variables representing hydrology-related landscape characteristics (e.g., infiltration capacity, surface storage capacity, stream density). Stream-connected surface water can leave via stream flow, influencing the rate at which surface-water may leave a location, therefore stream-connected and disconnected surface water were analyzed separately. Stream-connected surface water responded more strongly to wetter climatic conditions (i.e., accumulated) in landscapes with more lakes and less artificial drainage (e.g., ditching, tile drainage). Disconnected surface water responded more strongly to wetter climatic conditions when landscapes contained greater wetland density, fewer streams and a lower predicted rate of infiltration. From these findings, we can expect that the relationship between upstream and downstream waters will require consideration of hydrology-related landscape characteristics, and that climate-change related shifts in precipitation and evaporative demand will have an uneven effect on surface water expansion and contraction across the landscape.

The fibres and polyphenols in sea buckthorn (Hippophaë rhamnoides) extraction residues delay postprandial lipemia.

PubMed

Linderborg, Kaisa M; Lehtonen, Henna-Maria; Järvinen, Riikka; Viitanen, Matti; Kallio, Heikki

2012-06-01

The triacylglycerol (TAG) response to fatty meals containing dried and crushed berries or berry extraction residues was studied in a postprandial cross-over study with healthy normal-weight male volunteers. The berry material included sea buckthorn berries, sea buckthorn CO₂ extraction residue (CO₂-sea buckthorn) and sea buckthorn or black currant CO₂ and ethanol extraction residue (CO₂-EtOH-sea buckthorn, CO₂-EtOH-black currant). Extraction residues were used in order to advance the potential use of valuable side stream components containing polyphenols and fibre as human food. Compared to the berry-depleted control, all berry meals delayed lipemia, whereas there were no differences in the total area under the TAG response curve. The lipemic delay largely derived from the fibre rather than from the polyphenols. Even so, the effect of polyphenols may be complementary since sea buckthorn and CO₂-sea buckthorn showed significant differences in relation to control in a wider range of TAG areas than polyphenol-depleted CO₂-EtOH-sea buckthorn.

Sun-stirred Kraken Mare: Circulation in Titan's seas induced by solar heating and methane precipitation

NASA Astrophysics Data System (ADS)

Tokano, Tetsuya; Lorenz, Ralph D.

2016-05-01

Density-driven circulation in Titan's seas forced by solar heating and methane evaporation/precipitation is simulated by an ocean circulation model. If the sea is transparent to sunlight, solar heating can induce anti-clockwise gyres near the sea surface and clockwise gyres near the sea bottom. The gyres are in geostrophic balance between the radially symmetric pressure gradient force and Coriolis force. If instead the sea is turbid and most sunlight is absorbed near the sea surface, the sea gets stratified in warm seasons and the circulation remains weak. Precipitation causes compositional stratification of the sea to an extent that the sea surface temperature can be lower than the sea interior temperature without causing a convective overturning. Non-uniform precipitation can also generate a latitudinal gradient in the methane mole fraction and density, which drives a meridional overturning with equatorward currents near the sea surface and poleward currents near the sea bottom. However, gyres are more ubiquitous than meridional overturning.

The Impact of Sea Surface Temperature Front on Stratus-Sea Fog over the Yellow and East China Seas

NASA Astrophysics Data System (ADS)

Zhang, S.; Li, M.; Liu, F.

2013-12-01

A stratus-sea fog event occurred on 3 June 2011 over the Yellow and East China Seas (as shown in figure) is investigated observationally and numerically. Emphasis is put on the influences of the sea surface temperature front (SSTF) and of the synoptic circulations on the transition of stratus to sea fog. The southerly winds from a synoptic high pressure transport water vapor from the East China Sea to the Yellow Sea, while the subsidence induced by the high contributes to the formation of the temperature inversion on the top of the stratus or stratocumulus that appears mainly over the warm flank of a sea surface temperature front in the East China Sea. Forced by the SSTF, there is a secondary cell within the atmospheric boundary layer (ABL), with a sinking branch on the cold flank and a rising one on the warm flank of the SSTF. This sinking branch, in phase with the synoptic subsidence, forces the stratus or stratocumulus to lower in the elevation getting close to the sea surface as these clouds move northward driven by the southerly winds. The cloud droplets can either reach to the sea surface directly or evaporate into water vapor that may condense again when coming close to the cold sea surface to form fog. In this later case, the stratus and fog may separate. The cooling effect of cold sea surface counteracts the adiabatic heating induced by the subsidence and thus helps the transition of stratus to sea fog in the southern Yellow Sea. By smoothing the SSTF in the numerical experiment, the secondary cell weakens and the sea fog patches shrink obviously over the cold flank of the SSTF though the synoptic subsidence and moist advection still exist. A conceptual model is suggested for the transition of stratus to sea fog in the Yellow and East China Seas, which is helpful for the forecast of sea fog over these areas. The satellite visible image of the stratus-fog event. The fog appears in the Yellow Sea and the stratocumulus in the East China Sea.

Effects of Sea-Surface Waves and Ocean Spray on Air-Sea Momentum Fluxes

NASA Astrophysics Data System (ADS)

Zhang, Ting; Song, Jinbao

2018-04-01

The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer (MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.

Explosives screening on a vehicle surface

DOEpatents

Parmeter, John E.; Brusseau, Charles A.; Davis, Jerry D.; Linker, Kevin L.; Hannum, David W.

2005-02-01

A system for detecting particles on the outer surface of a vehicle has a housing capable of being placed in a test position adjacent to, but not in contact with, a portion of the outer surface of the vehicle. An elongate sealing member is fastened to the housing along a perimeter surrounding the wall, and the elongate sealing member has a contact surface facing away from the wall to contact the outer surface of the vehicle to define a test volume when the wall is in the test position. A gas flow system has at least one gas inlet extending through the wall for providing a gas stream against the surface of the vehicle within the test volume. This gas stream, which preferably is air, dislodges particles from the surface of the vehicle covered by the housing. The gas stream exits the test volume through a gas outlet and particles in the stream are detected.

Sensitivity of the sea ice concentration over the Kara-Barents Sea in autumn to the winter temperature variability over East Asia

NASA Astrophysics Data System (ADS)

Cho, K. H.; Chang, E. C.

2017-12-01

In this study, we performed sensitivity experiments by utilizing the Global/Regional Integrated Model system with different conditions of the sea ice concentration over the Kara-Barents (KB) Sea in autumn, which can affect winter temperature variability over East Asia. Prescribed sea ice conditions are 1) climatological autumn sea ice concentration obtained from 1982 to 2016, 2) reduced autumn sea ice concentration by 50% of the climatology, and 3) increased autumn sea ice concentration by 50% of climatology. Differently prescribed sea ice concentration changes surface albedo, which affects surface heat fluxes and near-surface air temperature. The reduced (increased) sea ice concentration over the KB sea increases (decreases) near-surface air temperature that leads the lower (higher) sea level pressure in autumn. These patterns are maintained from autumn to winter season. Furthermore, it is shown that the different sea ice concentration over the KB sea has remote effects on the sea level pressure patterns over the East Asian region. The lower (higher) sea level pressure over the KB sea by the locally decreased (increased) ice concentration is related to the higher (lower) pressure pattern over the Siberian region, which induces strengthened (weakened) cold advection over the East Asian region. From these sensitivity experiments it is clarified that the decreased (increased) sea ice concentration over the KB sea in autumn can lead the colder (warmer) surface air temperature over East Asia in winter.

Greenland's Biggest Losers

NASA Astrophysics Data System (ADS)

Box, J. E.; Hubbard, A.; Howat, I. M.; Csatho, B. M.; Decker, D. T.; Bates, R.; Tulaczyk, S. M.

2010-12-01

On 4 August, 2010, 275 square km of the front of the floating Petermann Glacier, far northwest Greenland, broke away. The glacier effectively retreated 15 km. Petermann has retreated 21 km since year 2000. Consulting available imagery, publications, and maps spanning the past century, we conclude that this is a retreat to a minimum extent in the observational record. This glacier is not the only ice are loser in Greenland. GRACE observations verify the concern of increased mass budget deficit. Retreat is ongoing at the 110 km wide Humboldt glacier and at the 23 km wide Zachariae ice stream. Humboldt, Zachariae, and Petermann (16 km wide) are among a handful of large marine-terminating outlets that have bedrock trenches that lead inland below sea level to the thick, interior reservoir of the ice sheet. Sleeping giants are awakening. Our area change survey of the 35 widest Greenland outlets indicates an annual marine-terminating glacier area loss rate in excess of 130 sq km per year. Here, we evaluate in this context the mechanisms for marine-terminating glacier retreat, dynamical responses to calving, and the apparent climate forcings. The work thus consults a suite of data sets, including: long-term meteorological station records; satellite-derived sea and land surface temperatures; satellite-derived sea ice extent; regional climate model output; oceanographic casts; time lapse cameras, surface elevation change, and tidal records. Cumulative area change at Greenland’s glacier top 5 “losers”. 2010 areas are measured ~1 month prior to the end of summer melt when the survey usually is made . We do not expect 2010 area changes to be much different using the future data. If anything, we expect the losses to be larger. Click here for a full resolution graphic.

Environmental DNA as a ‘Snapshot’ of Fish Distribution: A Case Study of Japanese Jack Mackerel in Maizuru Bay, Sea of Japan

PubMed Central

Takahashi, Kohji; Sawada, Hideki; Murakami, Hiroaki; Tsuji, Satsuki; Hashizume, Hiroki; Kubonaga, Shou; Horiuchi, Tomoya; Hongo, Masamichi; Nishida, Jo; Okugawa, Yuta; Fujiwara, Ayaka; Fukuda, Miho; Hidaka, Shunsuke; Suzuki, Keita W.; Miya, Masaki; Araki, Hitoshi; Yamanaka, Hiroki; Maruyama, Atsushi; Miyashita, Kazushi; Masuda, Reiji; Minamoto, Toshifumi; Kondoh, Michio

2016-01-01

Recent studies in streams and ponds have demonstrated that the distribution and biomass of aquatic organisms can be estimated by detection and quantification of environmental DNA (eDNA). In more open systems such as seas, it is not evident whether eDNA can represent the distribution and biomass of aquatic organisms because various environmental factors (e.g., water flow) are expected to affect eDNA distribution and concentration. To test the relationships between the distribution of fish and eDNA, we conducted a grid survey in Maizuru Bay, Sea of Japan, and sampled surface and bottom waters while monitoring biomass of the Japanese jack mackerel (Trachurus japonicus) using echo sounder technology. A linear model showed a high R2 value (0.665) without outlier data points, and the association between estimated eDNA concentrations from the surface water samples and echo intensity was significantly positive, suggesting that the estimated spatial variation in eDNA concentration can reflect the local biomass of the jack mackerel. We also found that a best-fit model included echo intensity obtained within 10–150 m from water sampling sites, indicating that the estimated eDNA concentration most likely reflects fish biomass within 150 m in the bay. Although eDNA from a wholesale fish market partially affected eDNA concentration, we conclude that eDNA generally provides a ‘snapshot’ of fish distribution and biomass in a large area. Further studies in which dynamics of eDNA under field conditions (e.g., patterns of release, degradation, and diffusion of eDNA) are taken into account will provide a better estimate of fish distribution and biomass based on eDNA. PMID:26933889

The Anthropogenic Effects of Hydrocarbon Inputs to Coastal Seas: Are There Potential Biogeochemical Impacts?

NASA Astrophysics Data System (ADS)

Anderson, M. R.; Rivkin, R. B.

2016-02-01

Petroleum hydrocarbon discharges related to fossil fuel exploitation have the potential to alter microbial processes in the upper ocean. While the ecotoxicological effects of such inputs are commonly evaluated, the potential for eutrophication from the constituent organic and inorganic nutrients has been largely ignored. Hydrocarbons from natural seeps and anthropogenic sources represent a measurable source of organic carbon for surface waters. The most recent (1989-1997) estimate of average world-wide input of hydrocarbons to the sea is 1.250 x 1012 g/yr ≈ 1.0 x 1012g C/year. Produced water from offshore platforms is the largest waste stream from oil and gas exploitation and contributes significant quantities of inorganic nutrients such as N, P and Fe. In coastal areas where such inputs are a significant source of these nutrients, model studies show the potential to shift production toward smaller cells and net heterotrophy. The consequences of these nutrient sources for coastal systems and semi enclosed seas are complex and difficult to predict, because (1) there is a lack of comprehensive data on inputs and in situ concentrations and (2) the is no conceptual or quantitative framework to consider their effects on ocean biogeochemical processes. Here we use examples from the North Sea (produced water discharges 1% total riverine input and NH4 3% of the annual riverine nitrogen load), the South China Sea (total petroleum hydrocarbons = 10-1750 μg/l in offshore waters), and the Gulf of Mexico (seeps = 76-106 x 109 gC/yr, Macondo blowout 545 x 109 gC) to demonstrate how hydrocarbon and produced water inputs can influence basin scale biogeochemical and ecosystem processes and to propose a framework to consider these effects on larger scales.

Disintegration of a marine-based ice stream - evidence from the Norwegian Channel, north-eastern North Sea

NASA Astrophysics Data System (ADS)

Morén, Björn M.; Petter Sejrup, Hans; Hjelstuen, Berit O.; Haflidason, Haflidi; Schäuble, Cathrina; Borge, Marianne

2014-05-01

The Norwegian Channel Ice Stream repeatedly drained large part of the Fennoscandian Ice Sheet through Mid and Late Pleistocene glacial stages. During parts of Marine Isotope Stages 2 and 3, glacial ice from Fennoscandia and the British Isles coalesced in the central North Sea and the Norwegian Channel Ice Stream reached the shelf edge on multiple occasions. Through the last decades a large amount of acoustic and sediment core data have been collected from the Norwegian Channel, providing a good background for studies focussing on stability- and development-controlling parameters for marine-based ice streams, the retreat rate of the Norwegian Channel Ice Stream, and the behaviour of the Fennoscandian Ice Sheet. Further, this improved understanding can be used to develop more accurate numerical climate models and models which can be used to model ice-sheet behaviour of the past as well as the future. This study presents new acoustic records and data from sediment cores which contribute to a better understanding of the retreat pattern and the retreat rate of the last ice stream that occupied the Norwegian Channel. From bathymetric and TOPAS seismic data, mega-scale glacial lineations, grounding-zone wedges, and end moraines have been mapped, thereby allowing us to reconstruct the pro- and subglacial conditions at the time of the creation of these landforms. It is concluded that the whole Norwegian Channel was deglaciated in just over 1 000 years and that for most of this time the ice margin was located at positions reflected by depositional grounding-zone wedges. Further work will explore the influence of channel shape and feeding of ice from western Norwegian fjords on this retreat pattern through numerical modelling.

Simulated atmospheric response to Gulf Stream variability

NASA Astrophysics Data System (ADS)

Hand, Ralf; Keenlyside, Noel; Omrani, Nour-Eddine; Latif, Mojib; Minobe, Shoshiro

2010-05-01

Though the ocean variability has a distinct low-frequent component on interannual to interdecadal timescales, a better understanding of the main features of air-sea interaction in the extratropical ocean might increase the predictive skill of climate models significantly. An insufficiently understood region in this context are the sharp SST-fronts connected to western boundary currents, which interact with the overlaying atmosphere by forcing low-level winds and evaporation. Recent studies show, that this response extends beyond the marine boundary layer and so might influence also the large-scale atmospheric circulation. In this work a 5 member ensemble of model runs from the AGCM ECHAM5 was analyzed focussing on the atmospheric response to the Gulf Stream. The analyzed experiment covered a time period of 138 years from 1870 to 2007 and was forced by observed SSTs and sea-ice concentration from the HadISST dataset. The experiment was performed at T106 horizontal resolution (~100km) and with 31 vertical levels up to 1 hPa. Simulated seasonal mean circulation indicate a convective response of the atmosphere in the Gulf Stream region similar to observations, with distinct low-level wind convergence, strong upward motion, and low-pressure over the warm SST flank of the Gulf Stream. An analysis of variance (ANOVA) suggests, that up to 25-30% of the variability of the summer precipitation in the Gulf Stream region are connected to the boundary conditions. The link between oceanic and atmospheric variability on seasonal to interannual timescales is investigated with composite and linear regression analysis. Results indicate that increased (decreased) precipitation is associated with stronger (weaker) low-level wind convergence, enhanced (reduced) upward motion, low (high) pressure, and warm (cold) SST anomalies in the region of the Gulf Stream. Currently sensitivity experiments with the same AGCM configuration are in progress.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Northwest). Sea-Run Cutthroat Trout

DTIC Science & Technology

1989-01-01

sockeye salmon ( Oncorhynchus nerka ), patterns in their home streams, and and coho salmon (Lowery 1966, significant abrupt deviations from the Armstrong...and cutthroat trout from the same stream, coho salmon ( Oncorhynchus kisutch) but varies widely by geographical (Cramer 1940; Sumner 1952; DeWTtt...salmon cutthroat trout diets (Dimick and Mote ( Oncorhynchus keta), pink salmon 1934; Lowery 1966; Allen 1969; ( Oncorhynchus gorbuscha), and Pacific

Biogeochemistry and Hydrology in Streams Impacted by Legacy Sediments and Urbanization: Implications for Stream Restoration

EPA Science Inventory

The groundwater–surface water interface, consisting of shallow groundwater adjacent to stream channels, is a hot spot for nitrogen removal processes, a storage zone for other solutes, and a target for restoration activities. Characterizing groundwater-surface water interac...

Nitrogen dynamics at the groundwater-surface water interface of a degraded urban stream (journal)

EPA Science Inventory

Urbanization degrades stream ecosystems by altering hydrology and nutrient dynamics, yet relatively little effort has been devoted to understanding biogeochemistry of urban streams at the ground water-surface water interface. This zone may be especially important for nitrogen re...

Tidal Energy: The benthic effects of an operational tidal stream turbine.

PubMed

O'Carroll, J P J; Kennedy, R M; Creech, A; Savidge, G

2017-08-01

The effect of modified flow on epifaunal boulder reef communities adjacent to the SeaGen, the world's first grid-compliant tidal stream turbine, were assessed. The wake of the SeaGen was modelled and the outputs were used in conjunction with positional and substrate descriptor variables, to relate variation in epifaunal community structure to the modified physical environment. An Artificial Neural Network (ANN) and Generalised Linear Model (GLM) were used to make predictions on the distribution of Ecological Status (ES) of epifaunal communities in relation to the turbulent wake of the SeaGen. ES was assigned using the High Energy Hard Substrate (HEHS) index. ES was largely High throughout the survey area and it was not possible to make predictions on the spatial distribution of ES using an ANN or GLM. Spatial pattern in epifaunal community structure was detected when the study area was partitioned into three treatment areas: area D1; within one rotor diameter (16 m) of the centre of SeaGen, area D2; between one and three rotor diameters, and area D3; outside of three rotor diameters. Area D1 was found to be significantly more variable than D2 and D3 in terms of epifaunal community structure, bare rock distributions and ES. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancing the Arctic Mean Sea Surface and Mean Dynamic Topography with CryoSat-2 Data

NASA Astrophysics Data System (ADS)

Stenseng, Lars; Andersen, Ole B.; Knudsen, Per

2014-05-01

A reliable mean sea surface (MSS) is essential to derive a good mean dynamic topography (MDT) and for the estimation of short and long-term changes in the sea surface. The lack of satellite radar altimetry observations above 82 degrees latitude means that existing mean sea surface models have been unreliable in the Arctic Ocean. We here present the latest DTU mean sea surface and mean dynamic topography models that includes CryoSat-2 data to improve the reliability in the Arctic Ocean. In an attempt to extrapolate across the gap above 82 degrees latitude the previously models included ICESat data, gravimetrical geoids, ocean circulation models and various combinations hereof. Unfortunately cloud cover and the short periods of operation has a negative effect on the number of ICESat sea surface observations. DTU13MSS and DTU13MDT are the new generation of state of the art global high-resolution models that includes CryoSat-2 data to extend the satellite radar altimetry coverage up to 88 degrees latitude. Furthermore the SAR and SARin capability of CryoSat-2 dramatically increases the amount of useable sea surface returns in sea-ice covered areas compared to conventional radar altimeters like ENVISAT and ERS-1/2. With the inclusion of CryoSat-2 data the new mean sea surface is improved by more than 20 cm above 82 degrees latitude compared with the previous generation of mean sea surfaces.

Effects of coded-wire-tagging on stream-dwelling Sea Lamprey larvae

USGS Publications Warehouse

Johnson, Nicholas; Swink, William D.; Dawson, Heather A.; Jones, Michael L.

2016-01-01

The effects of coded wire tagging Sea Lamprey Petromyzon marinus larvae from a known-aged stream-dwelling population were assessed. Tagged larvae were significantly shorter on average than untagged larvae from 3 to 18 months after tagging. However, 30 months after tagging, the length distribution of tagged and untagged larvae did not differ and tagged Sea Lampreys were in better condition (i.e., higher condition factor) and more likely to have undergone metamorphosis than the untagged population. The reason why tagged larvae were more likely to metamorphose is not clear, but the increased likelihood of metamorphosis could have been a compensatory response to the period of slower growth after tagging. Slower growth after tagging was consistent across larval size-classes, so handling and displacement from quality habitat during the early part of the growing season was likely the cause rather than the tag burden. The tag effects observed in this study, if caused by displacement and handling, may be minimized in future studies if tagging is conducted during autumn after growth has concluded for the year.

Polarimetric Doppler spectrum of backscattered echoes from nonlinear sea surface damped by natural slicks

NASA Astrophysics Data System (ADS)

Yang, Pengju; Guo, Lixin

2016-11-01

Based on the Lombardini et al. model that can predict the hydrodynamic damping of rough sea surfaces in the presence of monomolecular slicks and the "choppy wave" model (CWM) that can describe the nonlinear interactions between ocean waves, the modeling of time-varying nonlinear sea surfaces damped by natural or organic sea slicks is presented in this paper. The polarimetric scattering model of second-order small-slope approximation (SSA-II) with tapered wave incidence is utilized for evaluating co- and cross-polarized backscattered echoes from clean and contaminated CWM nonlinear sea surfaces. The influence of natural sea slicks on Doppler shift and spectral bandwidth of radar sea echoes is investigated in detail by comparing the polarimetric Doppler spectra of contaminated sea surfaces with those of clean sea surfaces. A narrowing of Doppler spectra in the presence of oil slicks is observed for both co- and cross-polarization, which is qualitatively consistent with wave-tank measurements. Simulation results also show that the Doppler shifts in slicks can increase or decrease, depending on incidence angles and polarizations.

Reclamation of potable water from mixed gas streams

DOEpatents

Judkins, Roddie R.; Bischoff, Brian L.; Debusk, Melanie Moses; Narula, Chaitanya

2016-07-19

An apparatus for separating a liquid from a mixed gas stream can include a wall, a mixed gas stream passageway, and a liquid collection assembly. The wall can include a first surface, a second surface, and a plurality of capillary condensation pores. The capillary condensation pores extend through the wall, and have a first opening on the first surface of the wall, and a second opening on the second surface of the wall. The pore size of the pores can be between about 2 nm to about 100 nm. The mixed gas stream passageway can be in fluid communication with the first opening. The liquid collection assembly can collect liquid from the plurality of pores.

Reclamation of potable water from mixed gas streams

DOEpatents

Judkins, Roddie R; Bischoff, Brian L; Debusk, Melanie Moses; Narula, Chaitanya

2013-08-20

An apparatus for separating a liquid from a mixed gas stream can include a wall, a mixed gas stream passageway, and a liquid collection assembly. The wall can include a first surface, a second surface, and a plurality of capillary condensation pores. The capillary condensation pores extend through the wall, and have a first opening on the first surface of the wall, and a second opening on the second surface of the wall. The pore size of the pores can be between about 2 nm to about 100 nm. The mixed gas stream passageway can be in fluid communication with the first opening. The liquid collection assembly can collect liquid from the plurality of pores.

Detailed real-time infrared radiation simulation applied to the sea surface

NASA Astrophysics Data System (ADS)

Zhang, Xuemin; Wu, Limin; Long, Liang; Zhang, Lisha

2018-01-01

In this paper, the infrared radiation characteristics of sea background have been studied. First, MODTRAN4.0 was used to calculate the transmittance of mid-infrared and far-infrared, and the solar spectral irradiance, the atmospheric and sea surface radiation. Secondly, according to the JONSWAP sea spectrum model, the different sea conditions grid model based on gravity wave theory was generated. The spectral scattering of the sun and the atmospheric background radiation was studied. The total infrared radiation of the sea surface was calculated. Finally, the infrared radiation of a piece of sea surface was mapped to each pixel of the detector, and the infrared radiation is simulated. The conclusion is that solar radiance has a great influence on the infrared radiance. When the detector angle is close to the sun's height angle, there will be bright spots on the sea surface.

Polarimetric infrared imaging simulation of a synthetic sea surface with Mie scattering.

PubMed

He, Si; Wang, Xia; Xia, Runqiu; Jin, Weiqi; Liang, Jian'an

2018-03-01

A novel method to simulate the polarimetric infrared imaging of a synthetic sea surface with atmospheric Mie scattering effects is presented. The infrared emission, multiple reflections, and infrared polarization of the sea surface and the Mie scattering of aerosols are all included for the first time. At first, a new approach to retrieving the radiative characteristics of a wind-roughened sea surface is introduced. A two-scale method of sea surface realization and the inverse ray tracing of light transfer calculation are combined and executed simultaneously, decreasing the consumption of time and memory dramatically. Then the scattering process that the infrared light emits from the sea surface and propagates in the aerosol particles is simulated with a polarized light Monte Carlo model. Transformations of the polarization state of the light are calculated with the Mie theory. Finally, the polarimetric infrared images of the sea surface of different environmental conditions and detection parameters are generated based on the scattered light detected by the infrared imaging polarimeter. The results of simulation examples show that our polarimetric infrared imaging simulation can be applied to predict the infrared polarization characteristics of the sea surface, model the oceanic scene, and guide the detection in the oceanic environment.

Holocene landscape response to seasonality of storms in the Mojave Desert

USGS Publications Warehouse

Miller, D.M.; Schmidt, K.M.; Mahan, S.A.; McGeehin, J.P.; Owen, L.A.; Barron, J.A.; Lehmkuhl, F.; Lohrer, R.

2010-01-01

New optically stimulated and radiocarbon ages for alluvial fan and lake deposits in the Mojave Desert are presented, which greatly improves the temporal resolution of surface processes. The new Mojave Desert climate-landscape record is particularly detailed for the late Holocene. Evidence from ephemeral lake deposits and landforms indicates times of sustained stream flow during a wet interval of the latter part of the Medieval Warm Period at ca. AD 1290 and during the Little Ice Age at ca. AD 1650. The former lakes postdate megadroughts of the Medieval Warm Period, whereas the latter match the Maunder Minimum of the Little Ice Age. Periods of alluvial fan aggradation across the Mojave Desert are 14-9 cal ka and 6-3 cal ka. This timing largely correlates to times of increased sea-surface temperatures in the Gulf of California and enhanced warm-season monsoons. This correlation suggests that sustained alluvial fan aggradation may be driven by intense summer-season storms. These data suggest that the close proximity of the Mojave Desert to the Pacific Ocean and the Gulf of California promotes a partitioning of landscape-process responses to climate forcings that vary with seasonality of the dominant storms. Cool-season Pacific frontal storms cause river flow, ephemeral lakes, and fan incision, whereas periods of intense warm-season storms cause hillslope erosion and alluvial fan aggradation. The proposed landscape-process partitioning has important implications for hazard mitigation given that climate change may increase sea-surface temperatures in the Gulf of California, which indirectly could increase future alluvial fan aggradation.

Quantifying the Hydrologic Effect of Climate Variability in the Lower Colorado Basin

NASA Astrophysics Data System (ADS)

Switanek, M.; Troch, P. A.

2007-12-01

Regional climate patterns are driven in large part by ocean states and associated atmospheric circulations, but modified through feedbacks from land surface conditions. The latter defines the climate elasticity of a river basin. Many regions that lie between semi-arid and semi-humid zones with seasonal rainfall, for instance, experience prolonged periods of wet and dry spells. Understanding the triggers that bring a river basin from one state (e.g. wet period of late 90s in the Colorado basin) abruptly to another state (multi-year drought initiated in 2001 to present) is what motivates the present study. Our research methodology investigates the causes of regional climate variability and its effect on hydrologic response. By correlating, using different monthly time lags, sea surface temperatures (SST) and sea level pressures (SLP) with basin averaged precipitation and surface temperature, we determine the most influential regions of the Pacific Ocean on lower Colorado climate variability. Using the most correlated data for each month, we derive precipitation and temperature distributions under similar conditions to that of the El Niño Southern Oscillation (ENSO). We compare the distributions of the climatic data, given ENSO constraints on SST and SLP, to the distributions considering non-ENSO years. Finally, we use observed stream flows and climatic data to determine the basin's climate elasticity. This allows us to quantitatively translate the predicted regional climate effects of ENSO on hydrologic response. Our presentation will use data for the Little Colorado as an example to demonstrate the procedure and produce preliminary results.

Compact turbidity meter

NASA Technical Reports Server (NTRS)

Hirschberg, J. G.

1979-01-01

Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.

Escape tectonics and the extrusion of Alaska: Past, present, and future

USGS Publications Warehouse

Redfield, T.F.; Scholl, D. W.; Fitzgerald, P.G.; Beck, M.E.

2007-01-01

The North Pacific Rim is a tectonically active plate boundary zone parts of which may be characterized as a laterally moving orogenic stream. Crustal blocks are transported along large-magnitude strike-slip faults in western Canada and central Alaska toward the Aleutian-Bering Sea subduction zones. Throughout much of the Cenozoic, at and west of its Alaskan nexus, the North Pacific Rim orogenic Stream (NPRS) has undergone tectonic escape. During transport, relatively rigid blocks acquired paleomagnetic rotations and fault-juxtaposed boundaries while flowing differentially through the system, from their original point of accretion and entrainment toward the free face defined by the Aleutian-Bering Sea subduction zones. Built upon classical terrane tectonics, the NPRS model provides a new framework with which to view the mobilistic nature of the western North American plate boundary zone. ?? 2007 The Geological Society of America.

New Mass-Conserving Bedrock Topography for Pine Island Glacier Impacts Simulated Decadal Rates of Mass Loss

NASA Astrophysics Data System (ADS)

Nias, I. J.; Cornford, S. L.; Payne, A. J.

2018-04-01

High-resolution ice flow modeling requires bedrock elevation and ice thickness data, consistent with one another and with modeled physics. Previous studies have shown that gridded ice thickness products that rely on standard interpolation techniques (such as Bedmap2) can be inconsistent with the conservation of mass, given observed velocity, surface elevation change, and surface mass balance, for example, near the grounding line of Pine Island Glacier, West Antarctica. Using the BISICLES ice flow model, we compare results of simulations using both Bedmap2 bedrock and thickness data, and a new interpolation method that respects mass conservation. We find that simulations using the new geometry result in higher sea level contribution than Bedmap2 and reveal decadal-scale trends in the ice stream dynamics. We test the impact of several sliding laws and find that it is at least as important to accurately represent the bedrock and initial ice thickness as the choice of sliding law.

Seasonal Ice Zone Reconnaissance Surveys Coordination

DTIC Science & Technology

2014-09-30

profiler (AXCP) ocean velocity shear (Morison), UpTempO buoy measurements of sea surface temperature (SST), sea level atmospheric pressure ( SLP ), and...and prediction…. Steele UpTempO buoy drops for SLP , SST, SSS, & surface velocity Visible and Thermal Images of the SIZ from the Coast Guard...Expendable CTD, AXCP= Air Expendable Current Profiler, SLP = Sea Level atmospheric Pressure, SST= Seas Surface Temperature, A/C= aircraft, SIC=Sea Ice

Earth observations taken from shuttle orbiter Discovery STS-70 mission

NASA Image and Video Library

1995-07-16

STS070-705-094 (13-22 JULY 1995) --- The southern half (about 70 miles in this view) of the Tifernine dunes of east-central Algeria appears on this view. The Tifernine dune-sea is one of the more dramatic features visible from the Shuttle when flying over the Sahara Desert. The dunes lie in a basin of dark-colored rocks heavily cut by winding stream courses (top right). Very occasional storms allow the streams to erode the dark rocks and transport the sediment to the basin. Westerly winds then mold the stream sediments into the complex dune shapes so well displayed here. North at bottom.

Toxicity of 4,346 chemicals to larval lampreys and fishes

USGS Publications Warehouse

Applegate, Vernon C.; Howell, John H.; Hall, A.E.; Smith, Manning A.

1957-01-01

The problem of controlling the sea lamprey in the upper Great Lakes has received considerable attention in recent years and requires no review here (Applegate and Moffett. 1955). Electromechanical weirs and traps and electrical barriers have been developed which can be successfully employed to block and/or destroy spawning runs of adult sea lampreys. These devices. when installed in all known $pawning streams. provide an effective method of reducing the numbers of sea lampreys in each lake basin. Initial efforts at control of the lamprey have employed these devices (Applegate. Smith. and Nielsen. 1952; Erkkila. Smith. and McLain. 1956).

Real-time science and outreach from the UNOLS fleet via HiSeasNet

NASA Astrophysics Data System (ADS)

Foley, S.; Berger, J.; Orcutt, J. A.; Brice, D.; Coleman, D. F.; Grabowski, E. M.

2010-12-01

The HiSeasNet satellite communications network has ben providing cost-effective, reliable, continuous Internet connectivity to the UNOLS oceanographic research fleet for nearly nine years. During that time, HiSeasNet has supported science and outreach programs with a variety of real-time interactions back to shore including videoconferencing, webcasting, shared whiteboards, and streaming high-definition video feeds. Solutions have varied in scale, cost, and capability. As real-time science and outreach becomes more common, experience with a variety of technologies continues to build, and more opportunities yet to explore.

Modeling sea-surface temperature and its variability

NASA Technical Reports Server (NTRS)

Sarachik, E. S.

1985-01-01

A brief review is presented of the temporal scales of sea surface temperature variability. Progress in modeling sea surface temperature, and remaining obstacles to the understanding of the variability is discussed.

Characterizing the surface charge of synthetic nanomembranes by the streaming potential method

PubMed Central

Datta, Subhra; Conlisk, A. T.; Kanani, Dharmesh M.; Zydney, Andrew L.; Fissell, William H.; Roy, Shuvo

2010-01-01

The inference of the surface charge of polyethylene glycol (PEG)-coated and uncoated silicon membranes with nanoscale pore sizes from streaming potential measurements in the presence of finite electric double layer (EDL) effects is studied theoretically and experimentally. The developed theoretical model for inferring the pore wall surface charge density from streaming potential measurements is applicable to arbitrary pore cross-sectional shapes and accounts for the effect of finite salt concentration on the ionic mobilities and the thickness of the deposited layer of PEG. Theoretical interpretation of the streaming potential data collected from silicon membranes having nanoscale pore sizes, with/without pore wall surface modification with PEG, indicates that finite electric double layer (EDL) effects in the pore-confined electrolyte significantly affect the interpretation of the membrane charge and that surface modification with PEG leads to a reduction in the pore wall surface charge density. The theoretical model is also used to study the relative significance of the following uniquely nanoscale factors affecting the interpretation of streaming potential in moderate to strongly charged pores: altered net charge convection by applied pressure differentials, surface-charge effects on ionic conduction, and electroosmotic convection of charges. PMID:20462592

Evolution of Meltwater on the McMurdo Ice Shelf, Antarctica During Two Summer Melt Seasons

NASA Astrophysics Data System (ADS)

Macdonald, G. J.; Banwell, A. F.; Willis, I.; Mayer, D. P.; Hansen, E. K.; MacAyeal, D. R.

2017-12-01

Ice shelves surround > 50% of Antarctica's coast and their response to climate change is key to the ice sheet's future and global sea-level rise. Observations of the development and drainage of 2750 lakes prior to the collapse of the Larsen B Ice Shelf, combined with our understanding of ice-shelf flexure/fracture, suggest that surface meltwater plays a key role in ice-shelf stability, although the present state of knowledge remains limited. Here, we report results of an investigation into the seasonal evolution of meltwater on the McMurdo Ice Shelf (MIS) during the 2015/16 and 2016/17 austral summers using satellite remote sensing, complemented by ground survey. Although the MIS is relatively far south (78° S), it experiences relatively high ablation rates in the west due to adiabatically warmed winds, making it a useful example of how meltwater could evolve on more southerly ice shelves in a warming climate. We calculate the areas and depths of ponded surface meltwater on the ice shelf at different stages of the two melt seasons using a modified NDWI approach and water-depth algorithm applied to both Landsat 8 and Worldview imagery. Data from two automatic weather stations on the ice shelf are used to drive a positive degree-day model to compare our observations of surface water volumes with modelled meltwater production. Results suggest that the spatial and temporal variations in surface meltwater coverage on the ice shelf vary not only with climatic conditions but also in response to other important processes. First, a rift that widens and propagates between the two melt seasons intercepts meltwater streams, redirecting flow and facilitating ponding elsewhere. Second, some lakes from previous years remain frozen over and become pedestalled, causing streams to divert around their perimeter. Third, surface debris conditions also cause large-scale spatial variation in melt rates and the flow and storage of water.

Ice stream motion facilitated by a shallow-deforming and accreting bed

PubMed Central

Spagnolo, Matteo; Phillips, Emrys; Piotrowski, Jan A.; Rea, Brice R.; Clark, Chris D.; Stokes, Chris R.; Carr, Simon J.; Ely, Jeremy C.; Ribolini, Adriano; Wysota, Wojciech; Szuman, Izabela

2016-01-01

Ice streams drain large portions of ice sheets and play a fundamental role in governing their response to atmospheric and oceanic forcing, with implications for sea-level change. The mechanisms that generate ice stream flow remain elusive. Basal sliding and/or bed deformation have been hypothesized, but ice stream beds are largely inaccessible. Here we present a comprehensive, multi-scale study of the internal structure of mega-scale glacial lineations (MSGLs) formed at the bed of a palaeo ice stream. Analyses were undertaken at macro- and microscales, using multiple techniques including X-ray tomography, thin sections and ground penetrating radar (GPR) acquisitions. Results reveal homogeneity in stratigraphy, kinematics, granulometry and petrography. The consistency of the physical and geological properties demonstrates a continuously accreting, shallow-deforming, bed and invariant basal conditions. This implies that ice stream basal motion on soft sediment beds during MSGL formation is accommodated by plastic deformation, facilitated by continuous sediment supply and an inefficient drainage system. PMID:26898399

Ground Water Atlas of the United States: Segment 13, Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands

USGS Publications Warehouse

Miller, James A.; Whitehead, R.L.; Oki, Delwyn S.; Gingerich, Stephen B.; Olcott, Perry G.

1997-01-01

Alaska is the largest State in the Nation and has an area of about 586,400 square miles, or about one-fifth the area of the conterminous United States. The State is geologically and topographically diverse and is characterized by wild, scenic beauty. Alaska contains abundant natural resources, including ground water and surface water of chemical quality that is generally suitable for most uses.The central part of Alaska is drained by the Yukon River and its tributaries, the largest of which are the Porcupine, the Tanana, and the Koyukuk Rivers. The Yukon River originates in northwestern Canada and, like the Kuskokwim River, which drains a large part of southwestern Alaska , discharges into the Bering Sea. The Noatak River in northwestern Alaska discharges into the Chukchi Sea. Major rivers in southern Alaska include the Susitna and the Matanuska Rivers, which discharge into Cook Inlet, and the Copper River, which discharges into the Gulf of Alaska . North of the Brooks Range, the Colville and the Sagavanirktok Rivers and numerous smaller streams discharge into the Arctic Ocean.In 1990, Alaska had a population of about 552,000 and, thus , is one of the least populated States in the Nation. Most of the population is concentrated in the cities of Anchorage, Fairbanks, and Juneau, all of which are located in lowland areas. The mountains, the frozen Arctic desert, the interior plateaus, and the areas covered with glaciers lack major population centers. Large parts of Alaska are uninhabited and much of the State is public land. Ground-water development has not occurred over most of these remote areas.The Hawaiian islands are the exposed parts of the Hawaiian Ridge, which is a large volcanic mountain range on the sea floor. Most of the Hawaiian Ridge is below sea level (fig. 31) . The State of Hawaii consists of a group of 132 islands, reefs, and shoals that extend for more than 1 ,500 miles from southeast to northwest across the central Pacific Ocean between about 155 and 1 79 degrees west longitude and about 19 to 28 degrees north latitude. The main inhabited islands are at the southeastern end of the group (fig. 31 ); not all the small islands, reefs, and shoals included in the State are shown. The Hawaiian islands are geologically youngest in the southeast and oldest in the northwest. This report discusses only the eight largest islands near the southeastern end of the group; these eight main islands account for practically all of the 6,426-square-mile land area of the State. The eight islands and their approximate size, in square miles, from southeast to northwest are Hawaii, 4 ,021; Maui, 728; Kahoolawe, 45; Lanai, 141; Molokai, 259; Oahu, 603; Kauai, 553; and Niihau, 71. The total resident population in 1995 was 1, 179,198, of which about 75 percent were on the island of Oahu. Honolulu, which is on Oahu, is the largest and most developed city and had a population of 369,485 in 1995. In addition to the resident population, a visitor population of about 150,000 has typically been present at any given time during the 1990's. Many of these visitors stay in Honolulu. The State Land Use Commission is responsible for classifying the lands of the State into one of four categories called districts: conservation, agricultural, urban, or rural (fig. 32). In 1995, conservation, agricultural, urban, and rural districts accounted for about 48, 47, 5, and 0.2 percent of the land area in the State, respectively. Conservation districts include areas necessary for protecting the State's watersheds and water resources and are typically located in high-altitude, high-rainfall areas. Much of the urban development in Hawaii is in the lowland coastal areas of each island. Agricultural irrigation can place large demands on the water resources; prior to the 1990's, one of the largest uses of water was for sugarcane irrigation. The five largest islands (Hawaii, Maui, Molokai, Oahu, and Kauai) have extensive areas of mountainous land where urbanization and large-scale agricultural operations are not feasible. The island of Hawaii is the largest island of the State (fig. 33) and has the highest altitude at 13,796 feet. Maui is about 10,000 feet above sea level in its eastern part and about 5,800 feet above sea level in its western part; a broad lowland area separates the two parts. Kahoolawe is the smallest of the eight major islands and is only about 1 ,500 feet above sea level in its eastern, highest part. Lanai is about 3,400 feet above sea level in its highest part, but much of the island is less than 1,000 feet above sea level. Molokai is mountainous in its eastern half, where it rises to about 5,000 feet above sea level, but most of the island is less than 1,000 feet above sea level. Oahu has a mountainous ridge along its eastern side and another mountainous area along the western side, where it rises to about 4,000 feet above sea level; however, most of Oahu is less than 1,000 feet above sea level. Kauai is about 5,200 feet above sea level in its central part, but from the base of the mountains shoreward, large areas of the island are less than 1,000 feet above sea level in the southern, eastern, and northern parts. Niihau is mostly less than 1 ,000 feet above sea level, except for a narrow ridge about 1 ,300 feet above sea level along its northeastern side. The topography of each island has a profound effect on development and climate.Puerto Rico and the Virgin Islands of the United States (fig. 66) are located about 1, 100 miles east-southeast of Miami, Fla. The islands are part of the Greater Antilles island chain which, along with the Lesser Antilles island chain, separates the Caribbean Sea from the Atlantic Ocean. Puerto Rico and the Virgin Islands lie approximately 100 miles south of the Puerto Rico Trench, a depression of the ocean floor that reaches depths of 30,249 feet , the deepest known part of the Atlantic Ocean. The main island of Puerto Rico is a rectangular-shaped island that extends approximately 110 miles from east to west and 40 miles from north to south (fig. 67). Puerto Rico and its three principal offshore islands- Vieques, Culebra, and Mona-have an overall area of about 3,471 square miles. The Virgin Islands are about 50 miles east of Puerto Rico and consist of about 80 islands and cays. In this report, the Virgin Islands include only the three island territories of the United States-St. Croix, St. Thomas, and St. John. The three island territories also are the largest and most important of the Virgin Islands chain , with respective areas of approximately 84, 32, and 19 square miles. The population of Puerto Rico was estimated to be about 3.4 million in 1985; approximately two-thirds of the people lived in cities, and the remaining one-third lived in rural areas. A population of about 104,000 inhabited the Virgin Islands in 1985; only about 30 percent of these people lived in urban areas. In Puerto Rico during 1985, ground water was the source of supply for approximately 16 percent of the population. Only a small percentage of the urban inhabitants of the Virgin Islands use ground water for water supply; however, ground water is an important supplemental source for rural inhabitants. Most of the population of Puerto Rico obtains its water supply from surface-water reservoirs. In the Virgin Islands, seawater desalination plants on St. Croix and St. Thomas are the principal sources of water supply for most urban areas; however, by law, all residences, hotels, and most public buildings are required to have cisterns supplied from rooftop precipitation collectors. Cruz Bay on St. John is primarily supplied by ground water. Culebra Island is primarily supplied by pipeline from Puerto Rico. Mona Island has no known source of water supply and is uninhabited. Puerto Rico and the three principal U.S. Virgin Islands are mountainous with central highland areas that rise to a maximum altitude of about 4,400 feet above sea level in Puerto Rico and about 1,100, 1,560, and 1,280 feet above sea level on St. Croix, St. Thomas, and St. John, respectively. In Puerto Rico , the Cordillera Central, the Sierra de Luquillo, and the Sierra de Cayey generally are oriented east-west and dominate the mountainous southern two-thirds of the island (fig. 67). An area of gently dipping limestone that has been deeply dissected by dissolution forms a wide band of karst topography along most of the north coast. Flat-lying coastal plains and alluvial valleys compose a discontinuous belt around much of the periphery of the island. The coastal plain is especially prominent along part of the south coast where coalescing fan deltas were deposited by adjacent streams to form a broad, continuous plain. In St. Thomas, flat, low-lying areas are limited to the Charlotte Amalie area and a few narrow beaches. St. John is similar to St. Thomas but has even less flat land; in St. John, flat land is limited mostly to the Cruz Bay and Coral Bay areas. The northwestern and eastern parts of St. Croix are formed by low mountains and rugged hills; however, the central and southwestern parts of the island are low-lying to gently rolling. Drainage on each of the islands characteristically consists of short, deeply incised streams that have steep gradients in the upper reaches. Drainage generally is radial from the central highlands to the sea. Few of the streams along the southern coast of Puerto Rico , its offshore islands, or the U.S. Virgin Islands are perennial, but flow only after major precipitation and during sustained wet periods.Precipitation in Puerto Rico and the Virgin Islands is highly variable, both seasonally and areally. Seasonally, a dry period begins in December and ends in March or April; it usually is followed by a period of intensive rainfall in April and May. A period of diminished rainfall in June and July is followed by the wet season that extends from August through November during which about 50 percent of annual rainfall occurs (fig. 68). Areally, the orographic effect of the steep topography of highland areas causes average annual precipitation to vary almost in direct relation to altitude, but it also is affected by prevailing wind direction. Average annual precipitation in Puerto Rico ranges from less than 40 inches on the southern coastal plain to greater than 200 inches in the mountains (fig. 69A). Annual precipitation averages about 75 inches on the windward north coast of Puerto Rico compared to about 30 inches on the lee side of the island along the southwestern coast. Annual precipitation averages from less than 30 to greater than 55 inches in the Virgin Islands (fig. 698).Runoff in Puerto Rico and the Virgin Islands also varies seasonally and areally in response to fluctuations in precipitation. Average annual runoff (1951-80) in Puerto Rico ranges from about 20 inches on the northern and southern coasts to greater than 100 inches in the mountainous rain forest of the Sierra de Luquillo (fig. 70). In general, runoff is greatest during two periods that coincide with periods when precipitation is greatest-in August through November and April through May. Most streams have little flow during dry periods except for the larger streams on the north, west, and south coasts of Puerto Rico that originate in the igneous and volcanic rocks of the interior. The northern and southern coastal streams especially are perennial in coastal areas where they are underlain by limestone and thick alluvium, and water from the limestone and alluvial aquifers discharges to the streams as base flow. Most of the precipitation is returned to the atmosphere by evapotranspiration-evaporation from the land and water surfaces and transpiration by plants. Average annual evaporation in Puerto Rico is estimated from pan evaporation to range from about 64 inches in the coastal areas to about 50 inches in the interior. Some of the water from precipitation is stored in reservoirs on the land surface. There are 11 surface-water reservoirs in Puerto Rico with capacities in excess of 5,000 acre-feet. One acre-foot is the volume of water that would cover 1 acre to a depth of 1 foot. The water in some of these impoundments is used for hydroelectric power generation and irrigation water supplies. However, six of the island's reservoirs are used principally for public water supply. The impoundments also increase evaporation because they increase the area of standing water. This water loss is especially significant in the south coast area, where pan evaporation is almost twice the annual rainfall. Some water from precipitation enters aquifers as groundwater recharge. Water that is stored in the aquifers might be released later either by withdrawal by wells, by evapotranspiration, or as seepage to streams.

On the use of the earth resources technology satellite /LANDSAT-1/ in optical oceanography

NASA Technical Reports Server (NTRS)

Maul, G. A.; Gordon, H. R.

1975-01-01

Observations of the Gulf Stream System in the Gulf of Mexico were obtained in synchronization with LANDSAT-1. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed by color (diffuse radiance) or sea state (specular radiance) effects associated with the cyclonic boundary even in the absence of a surface thermal signature. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation. Several spectra of upwelling diffuse light are computed as a function of the concentration of particles and yellow substance.

Gas-rich submarine exhalations during the 1989 eruption of Macdonald Seamount

NASA Astrophysics Data System (ADS)

C´e, J.-L.; Stoffers, P.; McMurtry, G.; Richnow, H.; Puteanus, D.; Sedwick, P.

1991-11-01

In January 1989 we observed submarine eruptions on the summit of Macdonald volcano during a French-German diving programme with the IFREMER submersible Cyana. Gas-streaming of large amounts of CH 4, CO 2 and SO 2 from summit vents, inferred from water column anomalies and observed by submersible, was accompanied on the sea surface by steam bursts, turbulence, red-glowing gases, and black bubbles comprising volcanic ash, sulphur and sulphides. Chloride depletion of water sampled on the floor of an actively degassing summit crater suggests either boiling and phase separation or additions of magmatic water vapour. Submersible observations, in-situ sampling and shipboard geophysical and hydrographic measurements show that the hydrothermal system of this hotspot volcano is distinguished by the influence of magmatic gases released from its shallow summit.

Charney's Influence on Modern Oceanography

NASA Astrophysics Data System (ADS)

Cane, M. A.

2017-12-01

In this talk I will review some of Jule Charney's impacts on current oceanographic research. He was of course a major seminal figure in geophysical fluid dynamics, an approach to understanding the atmosphere and oceans that has been thoroughly absorbed in contemporary thinking. In oceanography, his publications make vorticity dynamics the centerpiece of his analysis. Here I pursue two other aspects of his work. The first is to note that his 1955 paper "The Gulf Stream as an inertial boundary layer" appears to be the earliest numerical model in oceanography. The second is that his work on the equatorial undercurrent leads to a simplification of equatorial ocean structure that was exploited by Zebiak and Cane in their model for ENSO, and thus structures later views of how equatorial ocean dynamics influence sea surface temperature.

Black sea surface temperature anomaly on 5th August 1998 and the ozone layer thickness

NASA Astrophysics Data System (ADS)

Manev, A.; Palazov, K.; Raykov, St.; Ivanov, V.

2003-04-01

BLACK SEA SURFACE TEMPERATURE ANOMALY ON 5th AUGUST 1998 AND THE OZONE LAYER THICKNESS A. Manev , K. Palazov , St. Raykov, V. Ivanov Solar Terrestrial Influences Laboratory, Bulgarian Academy of Sciences amanev@abv.bg This paper focuses on the peculiarities of the Black Sea surface temperature anomaly on 05.08.1998. Researching the daily temperature changes in a number of control fields in the course of 8-10 years, we have found hidden correlations and anomalous deviations in the sea surface temperatures on a global scale. Research proves the statistical reliability of the temperature anomaly on the entire Black Sea surface registered on 04.-05.08.1998. In the course of six days around these dates the temperatures are up to 2°C higher than the maximum temperatures in this period in the other seven years. A more detailed analysis of the dynamics of the anomaly required the investigation of five Black Sea surface characteristic zones of 75x75 km. The analysis covers the period 20 days - 10 days before and 10 days after the anomaly. Investigations aimed at interpreting the reasons for the anomalous heating of the surface waters. We have tried to analyze the correlation between sea surface temperature and the global ozone above the Black Sea by using simultaneously data from the two satellite systems NOAA and TOMS. Methods of processing and comparing the data from the two satellite systems are described. The correlation coefficients values for the five characteristic zones are very high and close, which proves that the character of the correlation ozone - sea surface temperature is the same for the entire Black Sea surface. Despite the high correlation coefficient, we have proved that causality between the two phenomena at the time of the anomaly does not exit.

Intra-tidal variability of the vertical current structure in the western Dutch Wadden Sea

NASA Astrophysics Data System (ADS)

de Vries, Jurre; Ridderinkhof, Herman; van Aken, Hendrik

2014-05-01

Long-term velocity measurements are presented which were collected during three different seasons at one single location in an estuarine basin of the western Dutch Wadden Sea. These data are used to investigate the processes that determine the variability of the vertical current structure in the western Dutch Wadden Sea, in combination with simplified model runs using the one-dimensional water column model GETM (http://www.getm.eu/). Jay and Musiak [1996] were the first to suggest that intra-tidal variations in the vertical current might be important in determining the residual circulation patterns. More research [e.g. Stacey et al., 2001; Burchard and Hetland, 2010] has supported this hypothesis. Recently, lateral processes have been shown to influence the vertical current structure of alongstream velocity and hence the residual circulation [e.g. Lerczak and Geyer, 2004; Burchard and Schuttelaars, 2012]. Therefore to better understand the tidal dynamics in the western Dutch Wadden Sea, it is crucial to understand the processes that determine the vertical current structure. The two main findings of this study are that the complex bathymetry at the study site seems to produce an intra-tidal asymmetry in near-bed velocities and secondly that cross-stream processes strongly modify the current structure during late flood. Near-bed velocity and the bed roughness are greater during ebb than during flood. The GETM simulations suggest that vertical mixing during ebb is sufficient to destroy vertical stratification generated by classical tidal straining. The cross-stream current during late flood generate vertical stratification and drive an early reversal of the flood current near the surface. Therefore, it is hypothesized that this processes might increase the residual estuarine circulation at the study site. References - Burchard, H., Hetland, R.D. (2010), Quantifying the contributions of tidal straining and gravitational circulation to residual circulation in periodically stratified tidal estuaries, Journal of Physical Oceanography, 40(6), 1243-1262 - Burchard, H., Schuttelaars, H.M. (2012), Analysis of tidal straining as driver for estuarine circulation in well-mixed estuaries, Journal of Physical Oceanography, 42(2), 261-271 - Jay, D.A., Musiak, J.D. (1996), Internal tidal asymmetry in channel flows' origins and consequences, Coastal and Estuarine Studies, 50, 211-249 - Stacey, M.T., Burau J.R., Monismith, S.G. (2001), Creation of residual flows in a partially stratified estuary, Journal of Physical Oceanography, 34, 1410-1428

Analyses of Sea Surface Height, Bottom Pressure and Acoustic Travel Time in the Japan/East Sea

DTIC Science & Technology

2006-01-01

ANALYSES OF SEA SURFACE HEIGHT, BOTTOM PRESSURE AND ACOUSTIC TRAVEL TIME IN THE JAPAN/EAST SEA BY YONGSHENG XU A DISSERTATION SUBMITTED IN PARTIAL...COVERED 00-00-2006 to 00-00-2006 4. TITLE AND SUBTITLE Analyses of Sea Surface Height, Bottom Pressure and Acoustic Travel Time in the Japan/East Sea...1999 to July 2001. The PIESs recorded hourly vertical acoustic travel time and pressure, which are respectively good proxies of baroclinic and

Regional Stratification and Shear of the Various Streams Feeding the Philippine Straits

DTIC Science & Technology

2010-09-30

Streams Feeding the Philippine Straits Arnold L. Gordon Lamont-Doherty Earth Observatory 61 Route 9W Palisades , NY 10964-8000 tele: 845 365-8325...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Lamont-Doherty Earth Observatory,61 Route 9W, Palisades ,NY,10964-8000 8. PERFORMING ORGANIZATION REPORT...and is subsequently exported to the surrounding seas to close the overturning circulation cell . As these waters are reduced in oxygen by the rain of

Florida, Bahamas, Cuba and Gulf Stream, USA

NASA Image and Video Library

1992-08-08

This unique photo offers a view of the Florida peninsula, western Bahamas, north central Cuba and the deep blue waters of the Gulf Stream, that hugs the east coast of Florida (27.0N, 82.0W). In addition to being an excellent photograph for showing the geographical relationships between the variety of landforms in this scene, the typical effect of the land-sea breeze is very much in evidence as few clouds over water, cumulus build up over landmass.

Dynamics of Tropical Waves and Monsoons.

DTIC Science & Technology

1981-04-01

In the eastern and central parts of the South China Sea 4 the fast-streaming northeasterlies are modified rapidly by air- sea interaction. The...collected a set of Phase I W-MONEX data including radiosonde, pibal, ship, aircraft and satellite data. These data are being used to produce a sub...1978), contains a jet that is locally unstable in the middle of the region. When waves are introduced into this forced flow, they will grow and modify

Observed fingerprint of a weakening Atlantic Ocean overturning circulation.

PubMed

Caesar, L; Rahmstorf, S; Robinson, A; Feulner, G; Saba, V

2018-04-01

The Atlantic meridional overturning circulation (AMOC)-a system of ocean currents in the North Atlantic-has a major impact on climate, yet its evolution during the industrial era is poorly known owing to a lack of direct current measurements. Here we provide evidence for a weakening of the AMOC by about 3 ± 1 sverdrups (around 15 per cent) since the mid-twentieth century. This weakening is revealed by a characteristic spatial and seasonal sea-surface temperature 'fingerprint'-consisting of a pattern of cooling in the subpolar Atlantic Ocean and warming in the Gulf Stream region-and is calibrated through an ensemble of model simulations from the CMIP5 project. We find this fingerprint both in a high-resolution climate model in response to increasing atmospheric carbon dioxide concentrations, and in the temperature trends observed since the late nineteenth century. The pattern can be explained by a slowdown in the AMOC and reduced northward heat transport, as well as an associated northward shift of the Gulf Stream. Comparisons with recent direct measurements from the RAPID project and several other studies provide a consistent depiction of record-low AMOC values in recent years.

Drivers and potential predictability of summer time North Atlantic polar front jet variability

NASA Astrophysics Data System (ADS)

Hall, Richard J.; Jones, Julie M.; Hanna, Edward; Scaife, Adam A.; Erdélyi, Róbert

2017-06-01

The variability of the North Atlantic polar front jet stream is crucial in determining summer weather around the North Atlantic basin. Recent extreme summers in western Europe and North America have highlighted the need for greater understanding of this variability, in order to aid seasonal forecasting and mitigate societal, environmental and economic impacts. Here we find that simple linear regression and composite models based on a few predictable factors are able to explain up to 35 % of summertime jet stream speed and latitude variability from 1955 onwards. Sea surface temperature forcings impact predominantly on jet speed, whereas solar and cryospheric forcings appear to influence jet latitude. The cryospheric associations come from the previous autumn, suggesting the survival of an ice-induced signal through the winter season, whereas solar influences lead jet variability by a few years. Regression models covering the earlier part of the twentieth century are much less effective, presumably due to decreased availability of data, and increased uncertainty in observational reanalyses. Wavelet coherence analysis identifies that associations fluctuate over the study period but it is not clear whether this is just internal variability or genuine non-stationarity. Finally we identify areas for future research.

Seismic stratigraphy of the Mississippi-Alabama shelf and upper continental slope

USGS Publications Warehouse

Kindinger, J.L.

1988-01-01

The Mississippi-Alabama shelf and upper continental slope contain relatively thin Upper Pleistocene and Holocene deposits. Five stages of shelf evolution can be identified from the early Wisconsinan to present. The stages were controlled by glacioeustatic or relative sea-level changes and are defined by the stratigraphic position of depositional and erosional episodes. The stratigraphy was identified on seismic profiles by means of geomorphic pattern, high-angle clinoform progradational deposits, buried stream entrenchments, planar conformities, and erosional unconformities. The oldest stage (stage 1) of evolution occurred during the early Wisconsinan lowstand; the subaerially exposed shelf was eroded to a smooth seaward-sloping surface. This paleosurface is overlain by a thin (< 10 m) drape of transgressive deposits (stage 2). Stage 3 occurred in three phases as the late Wisconsinan sea retreated: (1) fluvial channel systems eroded across the shelf, (2) deposited a thick (90 m) shelf-margin delta, and (3) contemporaneously deposited sediments on the upper slope. Stage 4 included the rapid Holocene sea-level rise that deposited a relatively thin transgressive facies over parts of the shelf. The last major depositional episode (stage 5) was the progradation of the St. Bernard delta over the northwestern and central parts of the area. A depositional hiatus has occurred since the St. Bernard progradation. These Upper Quaternary shelf and slope deposits provide models for analogous deposits in the geologic record. Primarily, they are examples of cyclic sedimentation caused by changes in sea level and may be useful in describing short-term, sandy depositional episodes in prograding shelf and slope sequences. ?? 1988.

Relationship between clouds and sea surface temperatures in the western tropical Pacific

NASA Technical Reports Server (NTRS)

Arking, Albert; Ziskin, Daniel

1994-01-01

Analysis of four years of earth radiation budget, cloud, and sea surface temperature data confirms that cloud parameters change dramatically when and where sea surface temperatures increase above approximately 300K. These results are based upon monthly mean values within 2.5 deg x 2.5 deg grid points over the 'warm pool' region of the western tropical Pacific. The question of whether sea surface temperatures are influenced, in turn, by the radiative effects of these clouds (Ramanathan and Collins) is less clear. Such a feedback, if it exists, is weak. The reason why clouds might have so little influence, despite large changes in their longwave and shortwave radiative effects, might be that the sea surface responds to both the longwave heating and the shortwave cooling effects of clouds, and the two effects nearly cancel. There are strong correlations between the rate of change of sea surface temperature and any of the radiation budget parameters that are highly correlated with the incident solar flux-implying that season and latitude are the critical factors determining sea surface temperatures. With the seasonal or both seasonal and latitudinal variations removed, the rate of change of sea surface temperature shows no correlation with cloud-related parameters in the western tropical Pacific.

The Linear Perturbation Theory of Axially Symmetric Compressible Flow with Application to the Effect of Compressibility on the Pressure Coefficient at the Surface of a Body of Revolution

DTIC Science & Technology

1947-07-18

which + la constant constitute a surface vhlch say he called a streaa surface. The stream surface Is In torn Bode up of streaallnee. If a...potential and stream function would be, reapeetHely, VpX and ia ^r8. The stream awfaeoa would he right circular cylinders with axes along the x...there is a double infinity of methods. In general, !n transforming frem the compreeslhlo-flov field to the IncrwpreSBlble-flow field, streaa

Could a new ice core offer an insight into the stability of the West Antarctic Ice Sheet during the last interglacial?

NASA Astrophysics Data System (ADS)

Mulvaney, R.; Hindmarsh, R. C.

2013-12-01

Vaughan et al., in their 2011 paper 'Potential Seaways across West Antarctica' (Geochem. Geophys. Geosyst., 12, Q10004, doi:10.1029/2011GC003688), offer the intriguing prospect that substantial ice loss from the West Antarctic Ice Sheet during the previous interglacial period might have resulted in the opening of a seaway between the Weddell Sea and the Amundsen Sea. One of their potential seaways passes between the south western corner of the present Ronne Ice Shelf and the Pine Island Bay, through what is currently the course of the Rutford Ice Stream, between the Ellsworth Mountains and the Fletcher Promontory. To investigate whether this seaway could have existed (and to recover a paleoclimate and ice sheet history from the Weddell Sea), a team from the British Antarctic Survey and the Laboratoire de Glaciologie et Géophysique de l'Environnement drilled an ice core from a close to a topographic dome in the ice surface on the Fletcher Promontory in January 2012, reaching the bedrock at 654.3m depth from the surface. The site was selected to penetrate directly through the centre of a Raymond cupola observed in internal radar reflections from the ice sheet, with the intention that this would ensure we obtained the oldest ice available from the Fletcher Promontory. The basal ice sheet temperature measured was -18°C, implying the oldest ice would not have melted away from the base, while the configuration of the Raymond cupola in the radar horizons suggested stability in the ice dome topography during the majority of the Holocene. Our hypothesis is that chemical analysis of the ice core will reveal whether the site was ever relatively close to open sea water or ice shelf in the Rutford channel 20 km distant, rather than the current 700 km distance to sea ice/open water in either the Weddell Sea or the Amundsen Sea. While we do not yet have the chemistry data to test this hypothesis, in this poster we will discuss whether there is in reality any potential local meteoric ice remaining from the previous interglacial that could provide the evidence we need. We show likely age-depth models in an ice dome with a pronounced Raymond cupola and flat bedrock. The evidence from the stable water isotope temperature history from the site shows the Last Glacial Maximum/Holocene boundary substantially above the bedrock, implying the possibility of much older ice in the lowest ice layers.

Advancing Unmanned Aircraft Sensor Collection and Communication Capabilities with Optical Communications

NASA Astrophysics Data System (ADS)

Lukaczyk, T.

2015-12-01

Unmanned aircraft systems (UAS) are now being used for monitoring climate change over both land and seas. Their uses include monitoring of cloud conditions and atmospheric composition of chemicals and aerosols due to pollution, dust storms, fires, volcanic activity and air-sea fluxes. Additional studies of carbon flux are important for various ecosystem studies of both marine and terrestrial environments specifically, and can be related to climate change dynamics. Many measurements are becoming more complex as additional sensors become small enough to operate on more widely available small UAS. These include interferometric radars as well as scanning and fan-beam lidar systems which produce data streams even greater than those of high resolution video. These can be used to precisely map surfaces of the earth, ocean or ice features that are important for a variety of earth system studies. As these additional sensor capabilities are added to UAS the ability to transmit data back to ground or ship monitoring sites is limited by traditional wireless communication protocols. We describe results of tests of optical communication systems that provide significantly greater communication bandwidths for UAS, and discuss both the bandwidth and effective range of these systems, as well as their power and weight requirements both for systems on UAS, as well as those of ground-based receiver stations. We justify our additional use of Delay and Disruption Tolerant Networking (DTN) communication protocols with optical communication methods to ensure security and continuity of command and control operations. Finally, we discuss the implications for receiving, geo-referencing, archiving and displaying data streams from sensors communicated via optical communication to better enable real-time anomaly detection and adaptive sampling capabilities using multiple UAS or other unmanned or manned systems.

Late Cretaceous and Paleogene sedimentation along east side of San Joaquin basin, California

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

Reid, S.A.

1986-04-01

Depositional systems of the Late Cretaceous contrast with those of the Paleogene in the subsurface along the east side of the San Joaquin basin between Bakersfield and Fresno, California. Upper Cretaceous deposits include thick fan-delta and submarine fan facies of the Moreno and Panoche Formations, whereas the paleogene contains extensive nearshore, shelf, slope, and submarine fan deposits of the Lodo, Domengine, and Kreyenhagen Formations. These sediments were deposited on a basement surface having several west-trending ridges and valleys. West-flowing streams draining an ancestral Sierra Nevada of moderate relief formed prograding fan deltas that filled the valleys with thick wedges ofmore » nonmarine channel deposits, creating a bajada along the shoreline. Detrital material moved rapidly from the shoreline through a narrow shelf, into a complex of submarine fans in the subduction trough. During the early Eocene, a low sea level stand plus an end of Sierra Nevada uplift resulted in the erosion of the range to a peneplain. Stream-fed fan deltas were replaced by a major river system, which flowed west on about the present course of the Kern River. Following a rapid sea level increase, sand from the river system was deposited on the now broad shelf along a wide belt roughly coincident with California Highway 99. The river was also the point source for sand in a submarine fan northwest of Bakersfield. Both Upper Cretaceous and Paleogene depositional systems probably continue north along the east edge of the Great Valley. This proposed scenario for the east side of the San Joaquin is analogous to forearc deposits in the San Diego area, including the Cretaceous Rosario fan-delta and submarine fan system and the Eocene La Jolla and Poway nearshore, shelf, and submarine fan systems.« less

Biofilm-like properties of the sea surface and predicted effects on air-sea CO2 exchange

NASA Astrophysics Data System (ADS)

Wurl, Oliver; Stolle, Christian; Van Thuoc, Chu; The Thu, Pham; Mari, Xavier

2016-05-01

Because the sea surface controls various interactions between the ocean and the atmosphere, it has a profound function for marine biogeochemistry and climate regulation. The sea surface is the gateway for the exchange of climate-relevant gases, heat and particles. Thus, in order to determine how the ocean and the atmosphere interact and respond to environmental changes on a global scale, the characterization and understanding of the sea surface are essential. The uppermost part of the water column is defined as the sea-surface microlayer and experiences strong spatial and temporal dynamics, mainly due to meteorological forcing. Wave-damped areas at the sea surface are caused by the accumulation of surface-active organic material and are defined as slicks. Natural slicks are observed frequently but their biogeochemical properties are poorly understood. In the present study, we found up to 40 times more transparent exopolymer particles (TEP), the foundation of any biofilm, in slicks compared to the underlying bulk water at multiple stations in the North Pacific, South China Sea, and Baltic Sea. We found a significant lower enrichment of TEP (up to 6) in non-slick sea surfaces compared to its underlying bulk water. Moreover, slicks were characterized by a large microbial biomass, another shared feature with conventional biofilms on solid surfaces. Compared to non-slick samples (avg. pairwise similarity of 70%), the community composition of bacteria in slicks was increasingly (avg. pairwise similarity of 45%) different from bulk water communities, indicating that the TEP-matrix creates specific environments for its inhabitants. We, therefore, conclude that slicks can feature biofilm-like properties with the excessive accumulation of particles and microbes. We also assessed the potential distribution and frequency of slick-formation in coastal and oceanic regions, and their effect on air-sea CO2 exchange based on literature data. We estimate that slicks can reduce CO2 fluxes by up to 15%, and, therefore, play important local and regional roles in regulating air-sea interactions.

Sea level and turbidity controls on mangrove soil surface elevation change

USGS Publications Warehouse

Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

2015-01-01

Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

Nature Run for the North Atlantic Ocean Hurricane Region: System Evaluation and Regional Applications

NASA Astrophysics Data System (ADS)

Kourafalou, V.; Androulidakis, I.; Halliwell, G. R., Jr.; Kang, H.; Mehari, M. F.; Atlas, R. M.

2016-02-01

A prototype ocean Observing System Simulation Experiments (OSSE) system, first developed and data validated in the Gulf of Mexico, has been applied on the extended North Atlantic Ocean hurricane region. The main objectives of this study are: a) to contribute toward a fully relocatable ocean OSSE system by expanding the Gulf of Mexico OSSE to the North Atlantic Ocean; b) demonstrate and quantify improvements in hurricane forecasting when the ocean component of coupled hurricane models is advanced through targeted observations and assimilation. The system is based on the Hybrid Coordinate Ocean Model (HYCOM) and has been applied on a 1/250 Mercator mesh for the free-running Nature Run (NR) and on a 1/120 Mercator mesh for the data assimilative forecast model (FM). A "fraternal twin" system is employed, using two different realizations for NR and FM, each configured to produce substantially different physics and truncation errors. The NR has been evaluated using a variety of available observations, such as from AVISO, GDEM climatology and GHRSST observations, plus specific regional products (upper ocean profiles from air-borne instruments, surface velocity maps derived from the historical drifter data set and tropical cyclone heat potential maps derived from altimetry observations). The utility of the OSSE system to advance the knowledge of regional air-sea interaction processes related to hurricane activity is demonstrated in the Amazon region (salinity induced surface barrier layer) and the Gulf Stream region (hurricane impact on the Gulf Stream extension).

Groundwater and surface water dynamics of Na and Cl in an urban stream: effects of road salts

EPA Science Inventory

AbstractRoad salts are a growing environmental and health concern in urban watersheds. We examined groundwater (GW) and surface water (SW) dynamics of Na and Cl in an urban stream, Minebank Run (MBR), MD. We observed an increasing salinity trend in this restored stream. Current b...

IMPERVIOUS COVER AS A REGIONAL INDICATOR

EPA Science Inventory

Increases in impervious surface area in a watershed gives rise to changes in stream hydrology, stream channel morphology, increased pollutant runoff, and an increase in stream water temperature. These physical changes in the stream systems in turn give rise to impacts on stream ...

Post-Wildfire Potential for Carbon and Nitrogen Sequestration in the Southwestern United States in Restored Ephemeral and Intermittent Stream Channels

NASA Astrophysics Data System (ADS)

Callegary, J. B.; Norman, L.; Eastoe, C. J.; Sankey, J. B.; Youberg, A.

2016-12-01

The Kemp's ridley sea turtle (Lepidochelys kempii) is the most endangered sea turtle in the world, largely due to the limited geographic range of its nesting habitat. In the U.S., the majority of nesting occurs along Padre Island National Seashore (PAIS) in Texas. There has been limited research regarding the connection between beach geomorphology and Kemp's ridley nesting patterns, but studies concerning other sea turtle species suggest that certain beach geomorphology variables, such as beach slope and width, influence nest site selection. This research investigates terrestrial habitat variability of the Kemp's ridley sea turtle and quantifies the connection between beach geomorphology and Kemp's ridley nest site selection on PAIS and South Padre Island, Texas. Airborne topographic lidar data collected annually along the Texas coast from 2009 through 2012 was utilized to extract beach geomorphology characteristics, such as beach slope and width, dune height, and surface roughness, among others. The coordinates of observed Kemp's ridley nests from corresponding years were integrated with the aforementioned data in statistical models, which analyzed the influence of both general trends in geomorphology and individual morphologic variables on nest site selection. This research identified the terrestrial habitat variability of the Kemp's ridley and quantified the range of geomorphic characteristics of nesting beaches. Initial results indicate that dune width, beach width, and wind speed are significant variables in relation to nest presence, using an alpha of 0.1. Higher wind speeds and narrower beaches and foredunes favor nest presence. The average nest elevation is 1.13 m above mean sea level, which corresponds to the area directly below the potential vegetation line, and the majority of nesting occurs between the elevations of 0.68 m and 1.4 m above mean sea level. The results of this study include new information regarding Kemp's ridley beach habitat and its influence on nesting patterns that could be useful for the conservation and management of the species.

Growth and survival of sea lampreys from metamorphosis to spawning in Lake Huron

USGS Publications Warehouse

Swink, William D.; Johnson, Nicholas S.

2014-01-01

Larval Sea Lampreys Petromyzon marinus live burrowed in stream bottoms and then metamorphose into their parasitic stage. Among larvae that metamorphose in a given year (i.e., parasitic cohort), autumn out-migrants (October–December) to the Laurentian Great Lakes can feed on fish for up to 6 months longer than spring outmigrants (March–May), which overwinter in streams without feeding. We evaluated whether the season of outmigration affected growth or survival of newlymetamorphosed Sea Lampreys in LakeHuron. Newlymetamorphosed individuals (n=2,718) from three parasitic cohorts were netted during their out-migration from BlackMallard Creek, Michigan, to LakeHuron during autumn 1997 through spring 2000; each out-migrant was injected with a sequentially numbered coded wire tag and was released back into the creek. After up to 18 months of feeding in the Great Lakes, 224 (8.2%) Sea Lampreys were recaptured (in 1999–2001) as upstream-migrating adults in tributaries to Lakes Huron and Michigan. Recovery rates of autumn and spring out-migrants as adults were 9.4% and 7.8%, respectively, and these rates did not significantly differ. Overwinter feeding (i.e., as parasites) by autumn out-migrants did not produce adult mean sizes greater than those of spring out-migrants. Because we detected no growth or survival differences between autumn and spring out-migrants, the capture of newly metamorphosed Sea Lampreys at any point during their out-migration should provide equal reductions in damage to Great Lakes fisheries. The absence of a difference in growth or survival between autumn and spring out-migrants is an aspect of Sea Lamprey life history that yields resiliency to this invasive parasite and complicates efforts for its control in the Great Lakes.

Development of a pH/alkalinity treatment model for applications of the lampricide TFM to streams tributary to the Great Lakes

USGS Publications Warehouse

Bills, Terry D.; Boogaard, Michael A.; Johnson, David A.; Brege, Dorance C.; Scholefield, Ronald J.; Westman, R. Wayne; Stephens, Brian E.

2003-01-01

It has long been known that the toxicity of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is influenced by chemical and physical properties of water. As the pH, conductivity, and alkalinity of water increase, greater concentrations of TFM are required to kill sea lamprey (Petromyzon marinus) larvae. Consequently, the concentration of TFM required for effective treatment varies among streams. Brown trout (Salmo trutta) and sea lamprey larvae were exposed to a series of TFM concentrations in a continuous-flow diluter for 12 h. Twenty five exposures were conducted at various water alkalinities and pHs that treatment personnel encounter during lampricide treatments. Survival/mortality data were analyzed for lampricide concentrations that produced 50 and 99.9% mortality (LC50 and LC99.9) for sea lamprey larvae and 25 and 50% mortality (LC25 and LC50) for brown trout. Linear regression analyses were performed for each set of tests for each selected alkalinity by comparing the 12-h post exposure LC99.9 sea lamprey data and LC25 brown trout data at each pH. Mortality data from on-site toxicity tests conducted by lampricide control personnel were compared to predicted values from the pH/alkalinity prediction model. Of the 31 tests examined, 27 resulted in the LC100s (lowest TFM concentration where 100% mortality of sea lamprey was observed after 12 h of exposure) falling within 0.2 mg/L of the predicted sea lamprey minimum lethal (LC99.9) range. The pH/alkalinity prediction model provides managers with an operational tool that reduces the amount of TFM required for effective treatment while minimizing the impact on non-target organisms.

Sensitivity of Offshore Surface Fluxes and Sea Breezes to the Spatial Distribution of Sea-Surface Temperature

NASA Astrophysics Data System (ADS)

Lombardo, Kelly; Sinsky, Eric; Edson, James; Whitney, Michael M.; Jia, Yan

2018-03-01

A series of numerical sensitivity experiments is performed to quantify the impact of sea-surface temperature (SST) distribution on offshore surface fluxes and simulated sea-breeze dynamics. The SST simulations of two mid-latitude sea-breeze events over coastal New England are performed using a spatially-uniform SST, as well as spatially-varying SST datasets of 32- and 1-km horizontal resolutions. Offshore surface heat and buoyancy fluxes vary in response to the SST distribution. Local sea-breeze circulations are relatively insensitive, with minimal differences in vertical structure and propagation speed among the experiments. The largest thermal perturbations are confined to the lowest 10% of the sea-breeze column due to the relatively high stability of the mid-Atlantic marine atmospheric boundary layer (ABL) suppressing vertical mixing, resulting in the depth of the marine layer remaining unchanged. Minimal impacts on the column-averaged virtual potential temperature and sea-breeze depth translates to small changes in sea-breeze propagation speed. This indicates that the use of datasets with a fine-scale SST may not produce more accurate sea-breeze simulations in highly stable marine ABL regimes, though may prove more beneficial in less stable sub-tropical environments.

Enhanced Arctic Mean Sea Surface and Mean Dynamic Topography including retracked CryoSat-2 Data

NASA Astrophysics Data System (ADS)

Andersen, O. B.; Jain, M.; Stenseng, L.; Knudsen, P.

2014-12-01

A reliable mean sea surface (MSS) is essential to derive a good mean dynamic topography (MDT) and for the estimation of short and long-term changes in the sea surface. The lack of satellite radar altimetry observations above 82 degrees latitude means that existing mean sea surface models have been unreliable in the Arctic Ocean. We here present the latest DTU mean sea surface and mean dynamic topography models combining conventional altimetry with retracked CryoSat-2 data to improve the reliability in the Arctic Ocean. For the derivation of a mean dynamic topography the ESA GOCE derived geoid model have been used to constrain the longer wavelength. We present the retracking of C2 SAR data using various retrackes and how we have been able to combine data from various retrackers under various sea ice conditions. DTU13MSS and DTU13MDT are the newest state of the art global high-resolution models including CryoSat-2 data to extend the satellite radar altimetry coverage up to 88 degrees latitude and through combination with a GOCE geoid model completes coverage all the way to the North Pole. Furthermore the SAR and SARin capability of CryoSat-2 dramatically increases the amount of useable sea surface returns in sea-ice covered areas compared to conventional radar altimeters like ENVISAT and ERS-1/2. With the inclusion of CryoSat-2 data the new mean sea surface is improved by more than 20 cm above 82 degrees latitude compared with the previous generation of mean sea surfaces.

On the role of inter-basin surface salinity contrasts in global ocean circulation

NASA Astrophysics Data System (ADS)

Seidov, D.; Haupt, B. J.

2002-08-01

The role of sea surface salinity (SSS) contrasts in maintaining vigorous global ocean thermohaline circulation (TOC) is revisited. Relative importance of different generalizations of sea surface conditions in climate studies is explored. Ocean-wide inter-basin SSS contrasts serve as the major controlling element in global TOC. These contrasts are shown to be at least as important as high-latitudinal freshwater impacts. It is also shown that intra-basin longitudinal distribution of sea surface salinity, as well as intra- and inter-basin longitudinal distribution of sea surface temperature, is not crucial to conveyor functionality if only inter-basin contrasts in sea surface salinity are retained. This is especially important for paleoclimate and future climate simulations.

The influence of microclimates and fog on stable isotope signatures used in interpretation of regional hydrology: East Maui, Hawaii

USGS Publications Warehouse

Scholl, M.A.; Gingerich, S.B.; Tribble, G.W.

2002-01-01

Stable isotopes of precipitation, ground water and surface water measured on the windward side of East Maui from 0 to 3055 m altitude were used to determine recharge sources for stream flow and ground water. Correct interpretation of the hydrology using rainfall ??18O gradients with altitude required consideration of the influence of fog, as fog samples had isotopic signatures enriched by as much as 3??? in ??18O and 21??? in ??D compared to volume-weighted average precipitation at the same altitude. The isotopic analyses suggested that fog drip was a major component of stream flow and shallow ground water at higher altitudes in the watershed. 18O/altitude gradients in rainfall were comparable for similar microclimates on Maui (this study) and Hawaii Island (1990-1995 study), however, East Maui ??18O values for rain in trade-wind and high-altitude microclimates were enriched compared to those from Hawaii Island. Isotopes were used to interpret regional hydrology in this volcanic island aquifer system. In part of the study area, stable isotopes indicate discharge of ground water recharged at least 1000 m above the sample site. This deep-flowpath ground water was found in springs from sea level up to 240 m altitude, indicating saturation to altitudes much higher than a typical freshwater lens. These findings help in predicting the effects of ground water development on stream flow in the area. Published by Elsevier Science B.V.

The dependence of sea surface slope on atmospheric stability and swell conditions

NASA Technical Reports Server (NTRS)

Hwang, Paul A.; Shemdin, Omar H.

1988-01-01

A tower-mounted optical device is used to measure the two-orthogonal components of the sea surface slope. The results indicate that an unstable stratification at the air-sea interface tends to enhance the surface roughness. The presence of a long ocean swell system steers the primary direction of shortwave propagation away from wind direction, and may increase or reduce the mean square slope of the sea surface.

Coal resource occurrence and coal development potential maps of the southwest quarter of North Star School 15-minute quadrangle, Campbell County, Wyoming

USGS Publications Warehouse

,

1979-01-01

A study of the water resources of the Port Gamble Indian Reservation, Wash., has shown that there is probably a substantial quantity of good quality ground and surface water available to provide for further development of the reservation. Groundwater supplies are available from an artesian aquifer underlying the reservation near sea level. This aquifer is estimated to be capable of supplying at least 90 gallons per minute, continuously, without greatly increasing chances for seawater intrusion. This quantity of water is enough to supply about 800 to 900 additional residents on the reservation. Another artesian aquifer, relatively unexplored, was noted underlying the previously mentioned artesian aquifer. This lower aquifer may be capable of supplying additional groundwater for use on the reservation. Groundwater quality was found to be good for most uses, being moderately hard and having moderately high iron concentrations. No evidence of pollution of the groundwater was found during this study from either seawater intrusion or contamination from a nearby solid-waste disposal site. Surface-water resources studied on the reservation included two streams, Middle and Little Boston Creeks, whose 7-day low flows were estimated to be 0.4 and 0.2 cubic foot per second, respectively, for a 20-year estimated recurrence interval. The surface-water quality was also found to be good for most uses and was within the limits established by the U.S. Environmental Protection Agency for untreated drinking water. Thus, the water from these two streams, Middle and Little Boston Creeks, could be used as domestic supplies to supplement the groundwater withdrawals. (USGS)

Clear water radiances for atmospheric correction of coastal zone color scanner imagery

NASA Technical Reports Server (NTRS)

Gordon, H. R.; Clark, D. K.

1981-01-01

The possibility of computing the inherent sea surface radiance for regions of clear water from coastal zone color scanner (CZCS) imagery given only a knowledge of the local solar zenith angle is examined. The inherent sea surface radiance is related to the upwelling and downwelling irradiances just beneath the sea surface, and an expression is obtained for a normalized inherent sea surface radiance which is nearly independent of solar zenith angle for low phytoplankton pigment concentrations. An analysis of a data base consisting of vertical profiles of upwelled spectral radiance and pigment concentration, which was used in the development of the CZCS program, confirms the virtual constancy of the normalized inherent sea surface radiance at wavelengths of 520 and 550 nm for cases when the pigment concentration is less than 0.25 mg/cu m. A strategy is then developed for using the normalized inherent sea surface radiance in the atmospheric correction of CZCS imagery.

Trophic Interactions Between Insects and Stream-Associated Amphibians in Steep, Cobble-Bottom Streams of the Pacific Coast of North America

PubMed Central

Atwood, Trisha; Richardson, John S.

2012-01-01

Two native, stream-associated amphibians are found in coastal streams of the west coast of North America, the tailed frog and the coastal giant salamander, and each interacts with stream insects in contrasting ways. For tailed frogs, their tadpoles are the primary life stage found in steep streams and they consume biofilm from rock surfaces, which can have trophic and non-trophic effects on stream insects. By virtue of their size the tadpoles are relatively insensitive to stream insect larvae, and tadpoles are capable of depleting biofilm levels directly (exploitative competition), and may also “bulldoze” insect larvae from the surfaces of stones (interference competition). Coastal giant salamander larvae, and sometimes adults, are found in small streams where they prey primarily on stream insects, as well as other small prey. This predator-prey interaction with stream insects does not appear to result in differences in the stream invertebrate community between streams with and without salamander larvae. These two examples illustrate the potential for trophic and non-trophic interactions between stream-associated amphibians and stream insects, and also highlights the need for further research in these systems. PMID:26466536

Secular Change and Inter-annual Variability of the Gulf Stream Position, 1993-2013, 70°-55°W

NASA Astrophysics Data System (ADS)

Bisagni, J. J.; Gangopadhyay, A.

2016-12-01

The Gulf Stream (GS) is the northeastward-flowing surface limb of the Atlantic Ocean meridional overturning circulation (AMOC) "conveyer belt" that flows towards Europe and the Nordic Seas. Changes in the GS position after its separation from the coast at Cape Hatteras, i.e., from 75°W to 50°W, may be key to understanding the AMOC, sea level variability and ecosystem behavior along the east coast of North America. In this study we compare secular change and inter-annual variability (IAV) of annual mean Gulf Stream North Wall (GSNW) position with equator-ward Labrador Current (LC) transport along the southwestern Grand Banks near 52° W using 21 years (1993-2013) of satellite altimeter data. Results at 70°, 65°, 60° and 55° W show a southward secular trend for the GSNW, decreasing to the west. IAV of de-trended GSNW position residuals also decreases to the west. The long-term secular trend of annual mean upper layer LC transport increases near 52° W. Furthermore, IAV of LC transport residuals near 52° W is significantly correlated with GSNW position residuals at 55° W at a lag of +1-year. Spectral analysis reveals inter-annual peaks at 5-7 years and 2-3 years for the North Atlantic Oscillation (NAO), GSNW (65°-55°W) and LC transport for 1993-2013. A volume calculation using the LC rms residual of +1.04 Sv near 52° W results in an estimated GSNW residual of 79 km, or 63% of the observed 125.6 km (1.13°) rms value at 55° W. A similar volume calculation using the positive long-term, upper-layer LC transport trend accounts for 68% of the observed southward shift of the GSNW over the 1993-2013 period. Our work provides observational evidence of direct interaction between the upper layers of the sub-polar and sub-tropical gyres within the North Atlantic over secular and inter-annual time scales as suggested by previous workers.

Global warming related transient albedo feedback in the Arctic and its relation to the seasonality of sea ice

NASA Astrophysics Data System (ADS)

Andry, Olivier; Bintanja, Richard; Hazeleger, Wilco

2015-04-01

The Arctic is warming two to three times faster than the global average. Arctic sea ice cover is very sensitive to this warming and has reached historic minima in late summer in recent years (i.e. 2007, 2012). Considering that the Arctic Ocean is mainly ice-covered and that the albedo of sea ice is very high compared to that of open water, the change in sea ice cover is very likely to have a strong impact on the local surface albedo feedback. Here we quantify the temporal changes in surface albedo feedback in response to global warming. Usually feedbacks are evaluated as being representative and constant for long time periods, but we show here that the strength of climate feedbacks in fact varies strongly with time. For instance, time series of the amplitude of the surface albedo feedback, derived from future climate simulations (CIMP5, RCP8.5 up to year 2300) using a kernel method, peaks around the year 2100. This maximum is likely caused by an increased seasonality in sea-ice cover that is inherently associated with sea ice retreat. We demonstrate that the Arctic average surface albedo has a strong seasonal signature with a maximum in spring and a minimum in late summer/autumn. In winter when incoming solar radiation is minimal the surface albedo doesn't have an important effect on the energy balance of the climate system. The annual mean surface albedo is thus determined by the seasonality of both downwelling shortwave radiation and sea ice cover. As sea ice cover reduces the seasonal signature is modified, the transient part from maximum sea ice cover to its minimum is shortened and sharpened. The sea ice cover is reduced when downwelling shortwave radiation is maximum and thus the annual surface albedo is drastically smaller. Consequently the change in annual surface albedo with time will become larger and so will the surface albedo feedback. We conclude that a stronger seasonality in sea ice leads to a stronger surface albedo feedback, which accelerates melting of sea ice. Hence, the change in seasonality and the associated change in feedback strength is an integral part of the positive surface albedo feedback leading to Arctic amplification and diminishing sea ice cover in the next century when global climate warms.

The scaling of urban surface water abundance and impairment with city size

NASA Astrophysics Data System (ADS)

Steele, M. K.

2018-03-01

Urbanization alters surface water compared to nonurban landscapes, yet little is known regarding how basic aquatic ecosystem characteristics, such as the abundance and impairment of surface water, differ with population size or regional context. This study examined the abundance, scaling, and impairment of surface water by quantifying the stream length, water body area, and impaired stream length for 3520 cities in the United States with populations from 2500 to 18 million. Stream length, water body area, and impaired stream length were quantified using the National Hydrography Dataset and the EPA's 303(d) list. These metrics were scaled with population and city area using single and piecewise power-law models and related to biophysical factors (precipitation, topography) and land cover. Results show that abundance of stream length and water body area in cities actually increases with city area; however, the per person abundance decreases with population size. Relative to population, impaired stream length did not increase until city populations were > 25,000 people, then scaled linearly with population. Some variation in abundance and impairment was explained by biophysical context and land cover. Development intensity correlated with stream density and impairment; however, those relationships depended on the orientation of the land covers. When high intensity development occupied the local elevation highs (+ 15 m) and undeveloped land the elevation lows, the percentage of impaired streams was less than the opposite land cover orientation (- 15 m) or very flat land. These results show that surface water abundance and impairment across contiguous US cities are influenced by city size and by biophysical setting interacting with land cover intensity.

EM Bias-Correction for Ice Thickness and Surface Roughness Retrievals over Rough Deformed Sea Ice

NASA Astrophysics Data System (ADS)

Li, L.; Gaiser, P. W.; Allard, R.; Posey, P. G.; Hebert, D. A.; Richter-Menge, J.; Polashenski, C. M.

2016-12-01

The very rough ridge sea ice accounts for significant percentage of total ice areas and even larger percentage of total volume. The commonly used Radar altimeter surface detection techniques are empirical in nature and work well only over level/smooth sea ice. Rough sea ice surfaces can modify the return waveforms, resulting in significant Electromagnetic (EM) bias in the estimated surface elevations, and thus large errors in the ice thickness retrievals. To understand and quantify such sea ice surface roughness effects, a combined EM rough surface and volume scattering model was developed to simulate radar returns from the rough sea ice `layer cake' structure. A waveform matching technique was also developed to fit observed waveforms to a physically-based waveform model and subsequently correct the roughness induced EM bias in the estimated freeboard. This new EM Bias Corrected (EMBC) algorithm was able to better retrieve surface elevations and estimate the surface roughness parameter simultaneously. In situ data from multi-instrument airborne and ground campaigns were used to validate the ice thickness and surface roughness retrievals. For the surface roughness retrievals, we applied this EMBC algorithm to co-incident LiDAR/Radar measurements collected during a Cryosat-2 under-flight by the NASA IceBridge missions. Results show that not only does the waveform model fit very well to the measured radar waveform, but also the roughness parameters derived independently from the LiDAR and radar data agree very well for both level and deformed sea ice. For sea ice thickness retrievals, validation based on in-situ data from the coordinated CRREL/NRL field campaign demonstrates that the physically-based EMBC algorithm performs fundamentally better than the empirical algorithm over very rough deformed sea ice, suggesting that sea ice surface roughness effects can be modeled and corrected based solely on the radar return waveforms.

A three-dimensional model of co-rotating streams in the solar wind. 2: Hydrodynamic streams

NASA Technical Reports Server (NTRS)

Pizzo, V. J.

1979-01-01

Theoretical aspects of corotating solar wind dynamics on a global scale are explored by means of numerical simulations executed with a nonlinear, inviscid, adiabatic, single-fluid, three-dimensional (3-D) hydrodynamic formulation. A simple, hypothetical 3-D stream structure is defined on a source surface located at 35 solar radius and carefully documents its evolution to 1 AU under the influence of solar rotation. By manipulating the structure of this prototype configuration at the source surface, it is possible to elucidate the factors most strongly affecting stream evolution: (1) the intrinsic correlations among density, temperature, and velocity existing near the source; (2) the amplitude of the stream; (3) the longitudinal breadth of the stream; (4) the latitudinal breadth of the stream; and (5) the heliographic latitude of the centroid of the stream.

High rates of organic carbon processing in the hyporheic zone of intermittent streams.

PubMed

Burrows, Ryan M; Rutlidge, Helen; Bond, Nick R; Eberhard, Stefan M; Auhl, Alexandra; Andersen, Martin S; Valdez, Dominic G; Kennard, Mark J

2017-10-16

Organic carbon cycling is a fundamental process that underpins energy transfer through the biosphere. However, little is known about the rates of particulate organic carbon processing in the hyporheic zone of intermittent streams, which is often the only wetted environment remaining when surface flows cease. We used leaf litter and cotton decomposition assays, as well as rates of microbial respiration, to quantify rates of organic carbon processing in surface and hyporheic environments of intermittent and perennial streams under a range of substrate saturation conditions. Leaf litter processing was 48% greater, and cotton processing 124% greater, in the hyporheic zone compared to surface environments when calculated over multiple substrate saturation conditions. Processing was also greater in more saturated surface environments (i.e. pools). Further, rates of microbial respiration on incubated substrates in the hyporheic zone were similar to, or greater than, rates in surface environments. Our results highlight that intermittent streams are important locations for particulate organic carbon processing and that the hyporheic zone sustains this fundamental process even without surface flow. Not accounting for carbon processing in the hyporheic zone of intermittent streams may lead to an underestimation of its local ecological significance and collective contribution to landscape carbon processes.

New insights into West Greenland ice sheet/stream dynamics during the last glacial cycle.

NASA Astrophysics Data System (ADS)

Roberts, David; Lane, Tim; Rea, Brice; Cofaigh, Colm O.; Jamieson, Stewart; Vieli, Andreas; Rodes, Angel

2015-04-01

Onshore and offshore geomorphological mapping and deglacial chronologies from West Greenland constrain the nature and magnitude of ice advance and decay of the Greenland Ice Sheet (GrIS) during the last glacial cycle. Several ice stream troughs are known to have fed ice to the shelf edge during the last glacial cycle. Their offshore expression suggests that many were coalescent systems fed by smaller outlet glaciers and ice streams onshore but their central flow pathways were also controlled by geology and preglacial topography. The bed morphology of these large ice streams shows they operated over soft, deforming beds with drumlins, mega-scale glacial lineations and grounding zone wedges marking an offshore transition from predominant areal scour onshore. Records of offshore deglacial chronology remain sparse but the Uummannaq and Disko Bugt ice stream corridors are now well constrained. The Uummannaq ice stream (UIS) completely deglaciated from the continental shelf between 14.8 ka and 11.0 ka in response to rising air temperatures, increasing JJA solar radiation and sea-level rise, but temporary standstills and the asynchronous retreat history of its feeder zones suggest that topography/bathymetry strongly modulated retreat rates as ice became 'locked' back into the coastal fjord system. Initial reconstructions of behaviour UIS discounted an oceanic role in early deglaciation and favoured retreat from the mid-shelf and inner-shelf prior to the Younger Dryas but both these concepts remain under investigation. In Disko Bugt, Jakobshavn Isbrae deglaciated later than the UIS and remained on the outer shelf during the Younger Dyras stadial (12.8 - 11.7 cal. kyrs BP) only reaching in the inner coast fjords at approximately 10.0 ka. The later deglaciation of the Disko system (despite similar external forcing mechanisms) was controlled by regional topographic/bathymetric contrasts in their respective trough morphologies. This hypothesis is supported by recent model output which indicates that non-linear retreat, grounding line stability and up-ice surface thinning is heavily influenced by both vertical and lateral constrictions in marine trough systems. While the offshore ice stream corridors are beginning to reveal their dynamic retreat history, knowledge of the inter-stream areas on the continental shelf remains very poor. The western, onshore sector of the GrIS has a much improved deglacial chronology derived from radiocarbon and new cosmogenic surface exposure dating undertaken in the last decade, but the deglacial history of wide swathes of the inner, mid and outer continental shelf remains completely unknown. The Hellefiske moraines on the West Greenland shelf were described in the late 1970's but little is known of ice sheet retreat behaviour across these areas. Understanding the deglacial signature of such regions is important if we are to use palaeo-reconstructions to understand ice sheet collapse/retreat mechanisms and to inform future model predictions.

Monitoring sea lamprey pheromones and their degradation using rapid stream-side extraction coupled with UPLC-MS/MS

USGS Publications Warehouse

Wang, Huiyong; Johnson, Nicholas; Bernardy, Jeffrey; Hubert, Terry; Li, Weiming

2013-01-01

Pheromones guide adult sea lamprey (Petromyzon marinus) to suitable spawning streams and mates, and therefore, when quantified, can be used to assess population size and guide management. Here, we present an efficient sample preparation method where 100 mL of river water was spiked with deuterated pheromone as an internal standard and underwent rapid field-based SPE and elution in the field. The combination of field extraction with laboratory UPLC-MS/MS reduced the sample consumption from 1 to 0.1 L, decreased the sample process time from more than 1 h to 10 min, and increased the precision and accuracy. The sensitivity was improved more than one order of magnitude compared with the previous method. The influences of experimental conditions were assessed to optimize the separation and peak shapes. The analytical method has been validated by studies of stability, selectivity, precision, and linearity and by the determination of the limits of detection and quantification. The method was used to quantify pheromone concentration from five streams tributary to Lake Ontario and to estimate that the environmental half-life of 3kPZS is about 26 h.

Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California

NASA Astrophysics Data System (ADS)

Schumann, R. Randall; Pigati, Jeffrey S.; McGeehin, John P.

2016-09-01

Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, leaving a relict floodplain as much as 12-14 m above the present channel. The period of falling sea level between the end of the last interglacial highstand at 80 ka and the last glacial lowstand at 21 ka was marked by erosion and incision in the uplands and by deposition of alluvial sediment on the exposed marine shelf. Sea level rose relatively rapidly following the last glacial lowstand of - 106 m, triggering a shift from an erosional to a depositional sedimentary regime. Accumulation of sediment occurred first through vertical and lateral accretion in broad, shallow channels on the shelf. Channel avulsion and delta sedimentation produced widespread deposition, creating lobes or wedges of sediment distributed across relatively large areas of the shelf during the latest Pleistocene. Backfilling of valleys onshore (landward of present sea level) appears to have progressed in a more orderly and predictable fashion throughout the Holocene primarily because the streams were confined to their valleys. Vertical aggradation locally reduced stream gradients, causing frequent overbank flooding and lateral channel shift by meandering and/or avulsion. Local channel gradient and morphology, short-term climate variations, and intrinsic controls also affected the timing and magnitudes of these cut, fill, and flood events, and are reflected in the thickness and spacing of the episodic alluvial sequences. Floodplain aggradation within the valleys continued until at least 500 years ago, followed by intensive arroyo cutting that abandoned the relict floodplains, forming alluvial terraces. Sedimentary evidence points to overgrazing and drought, followed by catastrophic flooding, in the mid-nineteenth century as factors that may have accelerated and dramatically enhanced arroyo formation on the island.

Water resources of Windward Oahu, Hawaii

USGS Publications Warehouse

Takasaki, K.J.; Hirashima, George Tokusuke; Lubke, E.R.

1969-01-01

Windward Oahu lies in a large cavity--an erosional remnant of the Koolau volcanic dome at its greatest stage of growth. Outcrops include volcanic rocks associated with caldera collapse and the main fissure zone which is marked by a dike complex that extends along the main axis of the dome. The fissure zone intersects and underlies the Koolau Range north of Waiahole Valley. South of Waiahole Valley, the crest of the Koolau Range is in the marginal dike zone, an area of scattered dikes. The crest of the range forms the western boundary of windward Oahu. Dikes, mostly vertical and parallel or subparallel to the fissure zone, control movement and discharge of ground water because they are less permeable than the rocks they intrude. Dikes impound or partly impound ground water by preventing or retarding its movement toward discharge points. The top of this water, called high-level water in Hawaii, is at an altitude of about 1,000 feet in the north end of windward Oahu and 400 feet near the south end in Waimanalo Valley. It underlies most of the area and extends near or to the surface in poorly permeable rocks in low-lying areas. Permeability is high in less weathered mountain areas and is highest farthest away from the dike complex. Ground-water storage fluctuates to some degree owing to limited changes in the level of the ground-water reservoir--maximum storage is about 60,000 million gallons. The fluctuations control the rate at which ground water discharges. Even at its lowest recorded level, the reservoir contains a major part of the storage capacity because most of the area is perennially saturated to or near the surface. Tunnels have reduced storage by about 26,000 million gallons--only a fraction of the total storage--by breaching dike controls. Much of the reduction in storage can be restored if the .breached dike controls are replaced by flow-regulating bulkheads. Perennial streams intersect high-level water and collectively form its principal discharge. The larger streams are those that cut deepest into high-level reservoirs. Except near the coast in the northern end of the area, where dikes are absent, total base flow of streams equals total ground-water discharge. Development of high-level water by tunnels and wells diverts ground-water discharge from streams, decreasing the base flow of these streams. Construction of Haiku tunnel decreased the flow of Kahaluu Stream, 2 ? miles away, by about 26 percent. The dependable flow of water is estimated at 118 mgd (million gallons per day), of which 84 mgd is discharged by streams, tunnels, springs, and wells The remaining 34 mgd is underflow, most of it discharging into the sea near the northern end of ,the area. Average flow is estimated at 220 mgd, of which 159 mgd is. inventoried flow and 61 mgd is estimated underflow. Specific capacity of wells tapping lava flows of the Koolau Volcanic Series ranges from less than 1 to 11 gallons per minute per foot of drawdown in the dike-complex zone and from 2 to 100 in the marginal dike zone. A transmissivity of 4,000,000 gallons per day per foot was determined for the basal aquifer. Permeabilities of rocks in high mountainous areas penetrated by water-development tunnels were compared by recession constants determined from free-flow drainage. Evapotranspiration was estimated from regression curves obtained by correlating median annual rainfall and median annual pan evaporation. Evapotranspiration values from these curves compared favorably w4th values obtained from water-budget listings of rainfall and measured ground-water flow. The chemical quality of water in wells and tunnels tapping rocks of the Koolau and Honolulu Volcanic Series is excellent. Except in a few isolated areas near the shore, the chloride content of the water from these sources is generally less than 100 parts per million. Wells tapping calcareous materials are subject to sea-water contamination under heavy pumping.

Seasonal variability of the Red Sea, from GRACE time-variable gravity and altimeter sea surface height measurements

NASA Astrophysics Data System (ADS)

Wahr, John; Smeed, David; Leuliette, Eric; Swenson, Sean

2014-05-01

Seasonal variability of sea surface height and mass within the Red Sea, occurs mostly through the exchange of heat with the atmosphere and wind-driven inflow and outflow of water through the strait of Bab el Mandab that opens into the Gulf of Aden to the south. The seasonal effects of precipitation and evaporation, of water exchange through the Suez Canal to the north, and of runoff from the adjacent land, are all small. The flow through the Bab el Mandab involves a net mass transfer into the Red Sea during the winter and a net transfer out during the summer. But that flow has a multi-layer pattern, so that in the summer there is actually an influx of cool water at intermediate (~100 m) depths. Thus, summer water in the southern Red Sea is warmer near the surface due to higher air temperatures, but cooler at intermediate depths (especially in the far south). Summer water in the northern Red Sea experiences warming by air-sea exchange only. The temperature profile affects the water density, which impacts the sea surface height but has no effect on vertically integrated mass. Here, we study this seasonal cycle by combining GRACE time-variable mass estimates, altimeter (Jason-1, Jason-2, and Envisat) measurements of sea surface height, and steric sea surface height contributions derived from depth-dependent, climatological values of temperature and salinity obtained from the World Ocean Atlas. We find good consistency, particularly in the northern Red Sea, between these three data types. Among the general characteristics of our results are: (1) the mass contributions to seasonal SSHT variations are much larger than the steric contributions; (2) the mass signal is largest in winter, consistent with winds pushing water into the Red Sea through the Strait of Bab el Mandab in winter, and out during the summer; and (3) the steric signal is largest in summer, consistent with summer sea surface warming.

30 CFR 817.57 - Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams. 817.57 Section 817.57 Mineral Resources OFFICE OF SURFACE... PERMANENT PROGRAM PERFORMANCE STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.57 Hydrologic balance: Surface...

30 CFR 817.57 - Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams. 817.57 Section 817.57 Mineral Resources OFFICE OF SURFACE... PERMANENT PROGRAM PERFORMANCE STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.57 Hydrologic balance: Surface...

Greenland ice cores tell tales on past sea level changes

NASA Astrophysics Data System (ADS)

Dahl-Jensen, D.

2017-12-01

All the deep ice cores drilled to the base of the Greenland ice sheet contain ice from the previous warm climate period, the Eemian 130-115 thousand years before present. This demonstrates the resilience of the Greenland ice sheet to a warming of 5 oC. Studies of basal material further reveal the presence of boreal forest over Greenland before ice covered Greenland. Conditions for Boreal forest implies temperatures at this time has been more than 10 oC warmer than the present. To compare the paleo-behavior of the Greenland ice sheet to the present in relation to sea level rise knowledge gabs include the reaction of ice streams to climate changes. To address this the international EGRIP-project is drilling an ice core in the center of the North East Greenland Ice Stream (NEGIS). The first results will be presented.

Earth Observations taken by the STS-109 crew

NASA Image and Video Library

2002-03-05

STS109-719-076 (1-12 March 2002) --- The astronauts on board the Space Shuttle Columbia took this 70mm picture featuring part of the eastern sea board. The oblique view looks northward from South Florida to the southern Appalachians. Most of the southeastern United States appears in crisp, clear air in the wake of a cold front that has pushed well off the mainland. Only a few jet stream and low-level clouds remain over South Florida and Gulf Stream.

Electronic research and technology requirements for marine resources

NASA Technical Reports Server (NTRS)

Ewing, G. C.

1971-01-01

The Woods Hole air/space oceanographic program for 1969 is discussed. Studies included: (1) monitoring the sharp temperature boundary of the Gulf Stream by microwave and infrared observation, (2) spectrophotometry of the Gulf Stream and the adjacent continental slope and shelf water over Georges Bank, (3) interpretation of cloud and other meteorological data in terms of the effects of wind and sun on the upper ocean, (4) a sea state test plan, (5) systems research, and (6) ocean data recovery by aircraft and satellite.

Evidence of Atlantic salmon Salmo salar fry movement between fresh water and a brackish environment.

PubMed

Taal, I; Rohtla, M; Saks, L; Svirgsden, R; Kesler, M; Matetski, L; Vetemaa, M

2017-08-01

This study reports descent of Atlantic salmon Salmo salar fry from their natal streams to brackish waters of the Baltic Sea and their use of this environment as an alternative rearing habitat before ascending back to freshwater streams. To the authors' knowledge, residency in a brackish environment has not previously been demonstrated in S. salar fry. Recruitment success and evolutionary significance of this alternative life-history strategy are presently not known. © 2017 The Fisheries Society of the British Isles.

Methanation of gas streams containing carbon monoxide and hydrogen

DOEpatents

Frost, Albert C.

1983-01-01

Carbon monoxide-containing gas streams having a relatively high concentration of hydrogen are pretreated so as to remove the hydrogen in a recoverable form for use in the second step of a cyclic, essentially two-step process for the production of methane. The thus-treated streams are then passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. This active carbon is reacted with said hydrogen removed from the feed gas stream to form methane. The utilization of the CO in the feed gas stream is appreciably increased, enhancing the overall process for the production of relatively pure, low-cost methane from CO-containing waste gas streams.

Method for removing undesired particles from gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Hyatt, D.E.; Bustard, C.J.; Sjostrom, S.

1998-11-10

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 11 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, M.D.; Schlager, R.J.; Ebner, T.G.; Stewart, R.M.; Bustard, C.J.

1999-04-13

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency. 5 figs.

Method and apparatus for decreased undesired particle emissions in gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Bustard, Cynthia Jean

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Method for removing undesired particles from gas streams

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1998-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

ESA's Soil Moisture dnd Ocean Salinity Mission - Contributing to Water Resource Management

NASA Astrophysics Data System (ADS)

Mecklenburg, S.; Kerr, Y. H.

2015-12-01

The Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, is the European Space Agency's (ESA) second Earth Explorer Opportunity mission. The scientific objectives of the SMOS mission directly respond to the need for global observations of soil moisture and ocean salinity, two key variables used in predictive hydrological, oceanographic and atmospheric models. SMOS observations also provide information on the characterisation of ice and snow covered surfaces and the sea ice effect on ocean-atmosphere heat fluxes and dynamics, which affects large-scale processes of the Earth's climate system. The focus of this paper will be on SMOS's contribution to support water resource management: SMOS surface soil moisture provides the input to derive root-zone soil moisture, which in turn provides the input for the drought index, an important monitoring prediction tool for plant available water. In addition to surface soil moisture, SMOS also provides observations on vegetation optical depth. Both parameters aid agricultural applications such as crop growth, yield forecasting and drought monitoring, and provide input for carbon and land surface modelling. SMOS data products are used in data assimilation and forecasting systems. Over land, assimilating SMOS derived information has shown to have a positive impact on applications such as NWP, stream flow forecasting and the analysis of net ecosystem exchange. Over ocean, both sea surface salinity and severe wind speed have the potential to increase the predictive skill on the seasonal and short- to medium-range forecast range. Operational users in particular in Numerical Weather Prediction and operational hydrology have put forward a requirement for soil moisture data to be available in near-real time (NRT). This has been addressed by developing a fast retrieval for a NRT level 2 soil moisture product based on Neural Networks, which will be available by autumn 2015. This paper will focus on presenting the above applications and used SMOS data products.

Effects of road salts on groundwater and surface water dynamics of socium and chloride in an urban restored stream

EPA Science Inventory

Road salts are a growing environmental concern in urban watersheds. We examined groundwater (GW) and surface water (SW) dynamics of Na+ and Cl− in Minebank Run (MBR), an urban stream in Maryland, USA. We observed an increasing salinity trend in this restored stream. Current basef...

Acoustic observations of gas bubble streams in the NW Black Sea as a method for estimation of gas flux from vent sites

NASA Astrophysics Data System (ADS)

Artemov, Yu. G.

2003-04-01

Relatively recent discovery of the natural CH_4 gas seepage from the sea bed had action upon the philosophy of CH_4 contribution to global budgets. So far as numerous gas vent sites are known, an acceptable method for released gas quantification is required. In particular, the questions should be answered as follows: 1) how much amount of gas comes into the water column due to a certain bubble stream, 2) how much amount of gas comes into the water column due to a certain seepage area of the see floor, 3) how much amount of gas diffuses into the water and how much gas phase enters the atmosphere. Echo-sounder is the habitual equipment for detecting gas plumes (flares) in the water column. To provide observations of gas seeps with bubbles tracking, single target and volume backscattering strength measurements, we use installed on board the R/V "Professor Vodyanitskiy" dual frequency (38 and 120 kHz) split-beam scientific echo-sounder SIMRAD EK-500. Dedicated software is developed to extract from the raw echo data and to handle the definite information for analyses of gas bubble streams features. This improved hydroacoustic techniques allows to determine gas bubbles size spectrum at different depths through the water column as well as rise velocity of bubbles of different sizes. For instance, bubble of 4.5 mm diameter has rising speed of 25.8 cm/sec at 105 m depth, while bubble of 1.7 mm diameter has rising speed of 16.3 cm/sec at 32 m depth. Using volume backscattering measurements in addition, it is possible to evaluate flux of the gas phase produced by methane bubble streams and to learn of its fate in the water column. Ranking of various gas plumes by flux rate value is available also. In this presentation results of acoustic observations at the shallow NW Black Sea seepage area are given.

Experimental sea slicks: Their practical applications and utilization for basic studies of air-sea interactions

NASA Astrophysics Data System (ADS)

Hühnerfuss, Heinrich; Garrett, W. D.

1981-01-01

Practical applications of organic surface films added to the sea surface date back to ancient times. Aristotle, Plutarch, and Pliny the Elder describe the seaman's practice of calming waves in a storm by pouring oil onto the sea [Scott, 1977]. It was also noted that divers released oil beneath the water surface so that it could rise and spread over the sea surface, thereby suppressing the irritating flicker associated with the passage of light through a rippled surface. From a scientific point of view, Benjamin Franklin was the first to perform experiments with oils on natural waters. His experiment with a `teaspoonful of oil' on Clapham pond in 1773 inspired many investigators to consider sea surface phenomena or to conduct experiments with oil films. This early research has been reviewed by Giles [1969], Giles and Forrester [1970], and Scott [1977]. Franklin's studies with experimental slicks can be regarded as the beginning of surface film chemistry. His speculations on the wave damping influence of oil induced him to perform the first qualitative experiment with artificial sea slicks at Portsmouth (England) in October of 1773. Although the sea was calmed and very few white caps appeared in the oil-covered area, the swell continued through the oiled area to Franklin's great disappointment.

Low post-glacial rebound rates in the Weddell Sea due to Late Holocene ice-sheet readvance

NASA Astrophysics Data System (ADS)

Bradley, Sarah L.; Hindmarsh, Richard C. A.; Whitehouse, Pippa; Bentley, Michael J.; King, Matt

2014-05-01

The Holocene deglaciation of West Antarctica resulted in widespread ice surface lowering. While many ice-sheet reconstructions generally assume a monotone Holocene retreat for the West Antarctica Ice sheet (WAIS) [Ivins et al., 2013; Peltier, 2004; Whitehouse et al., 2012], an increasing number of glaciological observations infer it is readvancing, following retreat behind the present-day margin[Siegert et al., 2013]. We will show that a readvance in the Weddell Sea region can reconcile two outstanding problems: (i) the present-day widespread occurrence of seemingly stable ice-streams grounded on beds that deepen inland in apparent contradiction to theory [Schoof, 2007]; and (ii) the inability of models of Glacial Isostatic Adjustment (GIA) to match present-day uplift rates [Whitehouse et al., 2012]. Combining a suite of ice loading histories that include a readvance with a model of GIA provides significant improvements to predictions of present-day uplift rates, and we are able to reproduce previously unexplained observations of subsidence in the southern sector of the Weddell Sea. We hypothesize that retreat behind present grounding lines occurred when the bed was lower, and isostatic recovery led to shallowing, ice sheet re-grounding and readvance. We will conclude that some sections of the current WAIS grounding line that are theoretically unstable, may be advancing and that the volume change of the WAIS may have been more complex in the Late Holocene than previously posited. This revised Holocene ice-loading history would have important implications for the GIA correction applied to Gravity Recovery and Climate Experiment (GRACE) data, likely resulting in a reduction in the GIA correction and a smaller estimate of present-day ice mass loss within the Weddell Sea region of the WAIS. Ivins, E. R., T. S. James, J. Wahr, E. J. O. Schrama, F. W. Landerer, and K. M. Simon (2013), Antarctic contribution to sea level rise observed by GRACE with improved GIA correction, Journal of Geophysical Research: Solid Earth, 118(6), 3126-3141. Peltier, W. R. (2004), Global glacial isostasy and the surface of the ice-age earth: The ice-5G (VM2) model and grace, Annu Rev Earth Pl Sc, 32, 111-149. Schoof, C. (2007), Ice sheet grounding line dynamics: Steady states, stability, and hysteresis, Journal of Geophysical Research: Earth Surface, 112(F3). Siegert, M., N. Ross, H. Corr, J. Kingslake, and R. Hindmarsh (2013), Late Holocene ice-flow reconfiguration in the Weddell Sea sector of West Antarctica, Quaternary Sci Rev, 78(0), 98-107. Whitehouse, P. L., M. J. Bentley, G. A. Milne, M. A. King, and I. D. Thomas (2012), A new glacial isostatic adjustment model for Antarctica: calibrated and tested using observations of relative sea-level change and present-day uplift rates, Geophys J Int, 190(3), 1464-1482.

Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

NASA Astrophysics Data System (ADS)

Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

2016-07-01

Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

Upwelling Dynamic Based on Satellite and INDESO Data in the Flores Sea

NASA Astrophysics Data System (ADS)

Kurniawan, Reski; Suriamihardja, D. A.; Hamzah Assegaf, Alimuddin

2018-03-01

Upwelling phenomenon is crucial to be forecasted, mainly concerning the information of potential fishery areas. Utilization of calibrated model for recorded upwelling such as INDESO gives benefit for historical result up to the present time. The aim of this study is to estimate areas and seasons of upwelling occurrences in the Flores Sea using data assimilation of satellite and modeling result. This study uses sea surface temperature, chlorophyll-a data from level 3 of MODIS image and sea surface height from satellite Jason-2 monthly for three years (2014-2016) and INDESO model data for sea surface temperature, sea surface height, and chlorophyll-a daily for three years (2014-2016). The upwelling is indicated by declining of sea surface temperature, sea surface height and increasing of chlorophyll-a. Verification is conducted by comparing the model result with recorded MODIS satellite image. The result shows that the area of southern Makassar Strait having occurrences of upwelling phenomenon every year starting in June, extended to July and August. The strongest upwelling occurred in 2015 covering more or less the area of 23,000 km2. The relation of monthly data of satellite has significantly correlated with daily data of INDESO model

Secular change and inter-annual variability of the Gulf Stream position, 1993-2013, 70°-55°W

NASA Astrophysics Data System (ADS)

Bisagni, James J.; Gangopadhyay, Avijit; Sanchez-Franks, Alejandra

2017-07-01

The Gulf Stream (GS) is the northeastward-flowing surface limb of the Atlantic Ocean's meridional overturning circulation (AMOC) ;conveyer belt; that flows towards Europe and the Nordic Seas. Changes in the GS position after its separation from the coast at Cape Hatteras, i.e., from 75°W to 50°W, may be key to understanding the AMOC, sea level variability and ecosystem behavior along the east coast of North America. In this study we compare secular change and inter-annual variability (IAV) of the Gulf Stream North Wall (GSNW) position with equator-ward Labrador Current (LC) transport along the southwestern Grand Banks near 52°W using 21 years (1993-2013) of satellite altimeter data. Results at 55°, 60°, and 65°W show a significant southward (negative) secular trend for the GSNW, decreasing to a small but insignificant southward trend at 70°W. IAV of de-trended GSNW position residuals also decreases to the west. The long-term secular trend of annual mean upper layer (200 m) LC transport near 52°W is positive. Furthermore, IAV of LC transport residuals near 52°W along the southwestern Grand Banks are significantly correlated with GSNW position residuals at 55°W at a lag of +1-year, with positive (negative) LC transport residuals corresponding to southward (northward) GSNW positions one year later. The Taylor-Stephens index (TSI) computed from the first principal component of the GSNW position from 79° to 65°W shows a similar relationship with a more distal LC index computed along altimeter ground track 250 located north of the Grand Banks across Hamilton Bank in the western Labrador Sea. Increased (decreased) sea height differences along ground track 250 are significantly correlated with a more southward (northward) TSI two years later (lag of +2-years). Spectral analysis of IAV reveals corresponding spectral peaks at 5-7 years and 2-3 years for the North Atlantic Oscillation (NAO), GSNW (70°-55°W) and LC transport near 52°W for the 1993-2013 period suggesting a connection between these phenomena. An upper-layer (200 m) slope water volume calculation using the LC IAV rms residual of +1.04 Sv near 52°W results in an estimated GSNW IAV residual of 79 km, or 63% of the observed 125.6 km (1.13°) rms value at 55°W. A similar upper-layer slope water volume calculation using the positive long-term, upper-layer LC transport trend accounts for 68% of the mean observed secular southward shift of the GSNW between 55° and 70°W over the 1993-2013 period. Our work provides additional observational evidence of important interactions between the upper layers of the sub-polar and sub-tropical gyres within the North Atlantic over both secular and inter-annual time scales as suggested by previous studies.

Three modes of interdecadal trends in sea surface temperature and sea surface height

NASA Astrophysics Data System (ADS)

Gnanadesikan, A.; Pradal, M.

2013-12-01

It might be thought that sea surface height and sea surface temperature would be tightly related. We show that this is not necessarily the case on a global scale. We analysed this relationship in a suite of coupled climate models run under 1860 forcing conditions. The models are low-resolution variants of the GFDL Earth System Model, reported in Galbraith et al. (J. Clim. 2011). 1. Correlated changes in global sea surface height and global sea surface temperature. This mode corresponds to opening and closing of convective chimneys in the Southern Ocean. As the Southern Ocean destratifies, sea ice formation is suppressed during the winter and more heat is taken up during the summer. This mode of variability is highly correlated with changes in the top of the atmosphere radiative budget and weakly correlated with changes in the deep ocean circulation. 2. Uncorrelated changes in global sea surface height and global sea surface temperature. This mode of variability is associated with interdecadal variabliity in tropical winds. Changes in the advective flux of heat to the surface ocean play a critical role in driving these changes, which also result in significant local changes in sea level. Changes sea ice over the Southern Ocean still result in changes in solar absorption, but these are now largely cancelled by changes in outgoing longwave radiation. 3. Anticorrelated changes in global sea surface height and global sea surface temperatures. By varying the lateral diffusion coefficient in the ocean model, we are able to enhance and suppress convection in the Southern and Northern Pacific Oceans. Increasing the lateral diffusion coefficients shifts the balance sources of deep water away from the warm salty deep water of the North Atlantic and towards cold fresh deep water from the other two regions. As a result, even though the planet as a whole warms, the deep ocean cools and sea level falls, with changes of order 30 cm over 500 years. The increase in solar absorption in polar regions is more than compensated by an increase in outgoing longwave radiation. Relationship between global SSH trend over a decade and (A) local SSH change over a decade (m/m). (B) Global SST change over a decade (m/K) (C) Portion of decadal SST change correlated with net radiation at the top of the atmosphere (m/K) (D) Portion of decadal SST change not correlated with net radiation at the top of the atmosphere.

Process for producing methane from gas streams containing carbon monoxide and hydrogen

DOEpatents

Frost, Albert C.

1980-01-01

Carbon monoxide-containing gas streams are passed over a catalyst capable of catalyzing the disproportionation of carbon monoxide so as to deposit a surface layer of active surface carbon on the catalyst essentially without formation of inactive coke thereon. The surface layer is contacted with steam and is thus converted to methane and CO.sub.2, from which a relatively pure methane product may be obtained. While carbon monoxide-containing gas streams having hydrogen or water present therein can be used only the carbon monoxide available after reaction with said hydrogen or water is decomposed to form said active surface carbon. Although hydrogen or water will be converted, partially or completely, to methane that can be utilized in a combustion zone to generate heat for steam production or other energy recovery purposes, said hydrogen is selectively removed from a CO--H.sub.2 -containing feed stream by partial oxidation thereof prior to disproportionation of the CO content of said stream.

Estimates of diffuse phosphorus sources in surface waters of the United States using a spatially referenced watershed model

USGS Publications Warehouse

Alexander, R.B.; Smith, R.A.; Schwarz, G.E.

2004-01-01

The statistical watershed model SPARROW (SPAtially Referenced Regression On Watershed attributes) was used to estimate the sources and transport of total phosphorus (TP) in surface waters of the United States. We calibrated the model using stream measurements of TP from 336 watersheds of mixed land use and spatial data on topography, soils, stream hydrography, and land use (agriculture, forest, shrub/grass, urban). The model explained 87% of the spatial variability in log transformed stream TP flux (kg yr-1). Predictions of stream yield (kg ha-1 yr-1) were typically within 45% of the observed values at the monitoring sites. The model identified appreciable effects of soils, streams, and reservoirs on TP transport, The estimated aquatic rates of phosphorus removal declined with increasing stream size and rates of water flushing in reservoirs (i.e. areal hydraulic loads). A phosphorus budget for the 2.9 million km2 Mississippi River Basin provides a detailed accounting of TP delivery to streams, the removal of TP in surface waters, and the stream export of TP from major interior watersheds for sources associated with each land-use type. ?? US Government 2004.

Sea surface temperature measurements with AIRS

NASA Technical Reports Server (NTRS)

Aumann, H.

2003-01-01

The comparison of global sea surface skin temperature derived from cloud-free AIRS super window channel at 2616 cm-1 (sst2616) with the Real-Time Global Sea Surface Temperature for September 2002 shows surprisingly small standard deviation of 0.44K.

Air - water temperature relationships in the trout streams of southeastern Minnesota’s carbonate - sandstone landscape

USGS Publications Warehouse

Krider, Lori A.; Magner, Joseph A.; Perry, Jim; Vondracek, Bruce C.; Ferrington, Leonard C.

2013-01-01

Carbonate-sandstone geology in southeastern Minnesota creates a heterogeneous landscape of springs, seeps, and sinkholes that supply groundwater into streams. Air temperatures are effective predictors of water temperature in surface-water dominated streams. However, no published work investigates the relationship between air and water temperatures in groundwater-fed streams (GWFS) across watersheds. We used simple linear regressions to examine weekly air-water temperature relationships for 40 GWFS in southeastern Minnesota. A 40-stream, composite linear regression model has a slope of 0.38, an intercept of 6.63, and R2 of 0.83. The regression models for GWFS have lower slopes and higher intercepts in comparison to surface-water dominated streams. Regression models for streams with high R2 values offer promise for use as predictive tools for future climate conditions. Climate change is expected to alter the thermal regime of groundwater-fed systems, but will do so at a slower rate than surface-water dominated systems. A regression model of intercept vs. slope can be used to identify streams for which water temperatures are more meteorologically than groundwater controlled, and thus more vulnerable to climate change. Such relationships can be used to guide restoration vs. management strategies to protect trout streams.

Atmospheric dynamics and habitability range in Earth-like aquaplanets obliquity simulations

NASA Astrophysics Data System (ADS)

Nowajewski, Priscilla; Rojas, M.; Rojo, P.; Kimeswenger, S.

2018-05-01

We present the evolution of the atmospheric variables that affect planetary climate by increasing the obliquity by using a general circulation model (PlaSim) coupled to a slab ocean with mixed layer flux correction. We increase the obliquity between 30° and 90° in 16 aquaplanets with liquid sea surface and perform the simulation allowing the sea ice cover formation to be a consequence of its atmospheric dynamics. Insolation is maintained constant in each experiment, but changing the obliquity affects the radiation budget and the large scale circulation. Earth-like atmospheric dynamics is observed for planets with obliquity under 54°. Above this value, the latitudinal temperature gradient is reversed giving place to a new regime of jet streams, affecting the shape of Hadley and Ferrel cells and changing the position of the InterTropical Convergence Zone. As humidity and high temperatures determine Earth's habitability, we introduce the wet bulb temperature as an atmospheric index of habitability for Earth-like aquaplanets with above freezing temperatures. The aquaplanets are habitable all year round at all latitudes for values under 54°; above this value habitability decreases toward the poles due to high temperatures.

Endocrine events associated with spawning behavior in the sea lamprey (Petromyzon marinus)

USGS Publications Warehouse

Linville, Jane E.; Hanson, Lee H.; Sower, Stacia A.

1987-01-01

Levels of estradiol, progesterone, and testosterone were determined in plasma of sea lamprey (Petromyzon marinus) undergoing certain behaviors associated with spawning in natural and artifical stream environments. Significantly higher levels of estradiol, progesterone, and testosterone were found in males than in females. In the artifical spawning channel, levels of estradiol were significantly higher in females exhibiting resting and swimming behaviors than in fanning, nest building, and spawning behaviors. No significant correlation was found with either progesterone or testosterone levels and the various reproductive behaviors. The data presented are the first experimental evidence that suggest gonadal steroids may be correlated with certain reproductive behaviors in the sea lamprey.

Bellingshausen Sea

NASA Image and Video Library

2017-12-08

A small hole in the clouds revealed newly formed sea ice in the Bellingshausen Sea next to an ice berg on Nov. 5, 2014 flight. Image Credit: NASA/Digital Mapping System NASA’s Operation IceBridge collected some rare images on a flight out of Punta Arenas, Chile on Nov. 5, 2014, on a science flight over western Antarctica dubbed Ferrigno-Alison-Abbott 01. The crew snapped a few shots of a calving front of the Antarctic ice sheet. This particular flight plan was designed to collect data on changes in ice elevation along the coast near the Ferrigno and Alison ice streams, on the Abbot Ice Shelf, and grounded ice along the Eights Coast.

Smoke in the Gulf of Mexico

NASA Technical Reports Server (NTRS)

2002-01-01

This Sea-viewing Wide Field-of-view Sensor (SeaWiFS) image of the Bay of Campeche, acquired January 17, 2001, shows a 300-kilometer long smoke plume streaming towards the northwest from around 19.4o North and 92o West, the location of the Akal oil field. In the lower right (southeast) corner of the image is the country of El Salvador, site of a magnitude 7.6 earthquake on January 13, 2001. On the Pacific side of Southern Mexico, the productive waters of the Gulf of Tehuantepec are visible. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Urban Stream Ecology

EPA Science Inventory

Urban watersheds characteristically have high impervious surface cover, resulting in high surface runoff and low infiltration following storms. In response, urban streams experience “flashy” stormflows, reduced baseflows, bank erosion, channel widening, and sedimentation. Urban ...

Tracking Changes in Dissolved Organic Matter Patterns in Perennial Headwater Streams Throughout a Hydrologic Year Using In-situ Sensors and Optical Properties

NASA Astrophysics Data System (ADS)

Armstrong, A.; Epting, S.; Hosen, J. D.; Palmer, M.

2015-12-01

Dissolved organic matter (DOM) plays a central role in freshwater streams but key questions remain unanswered about temporal patterns in its quantity and composition. DOM in perennial streams in the temperate zone is a complex mixture reflecting a variety of sources such as leached plant material, organic matter from surrounding soils, and microbial processes in the streams themselves. Headwater perennial streams in the Tuckahoe Creek watershed of the Atlantic coastal plain (Maryland, USA) drain a mosaic of land cover types including row crops, forests, and both forested and marshy small depressional wetlands. Wetland-stream surface hydrologic connections generally occur between mid-fall and late spring, coinciding with peak wetland hydrologic expression (i.e. highest groundwater levels and surface inundation extent). When inundated, these wetlands contain high DOM concentrations, and surface connections may serve as conduits for downstream export. We hypothesized that changes in wetland-stream surface hydrologic connectivity would affect patterns of DOM concentration and composition in these streams. We deployed 6 sondes equipped with fluorescent DOM sensors in 4 perennial streams, 1 forested wetland, and the larger downstream channel draining all study sites for the 2015 water year. The 4 headwater streams drain areas containing forested wetlands and have documented temporary channel connections. Combined with baseflow and stormflow sampling, the sondes provided 15 minute estimates of dissolved organic carbon (DOC) concentrations. This resolution provided insights into patterns of DOC concentration across temporal scales from daily rhythms to seasonal changes, during both baseflow and storm conditions. Discrete measurements of absorbance and fluorescence provided information about DOM composition throughout the study. Together these measurements give a detailed record of DOM dynamics in multiple perennial headwater streams for an entire year. This information could inform future studies, such as investigations into stream network scale thresholds in DOM cycling, carbon cycling modelling for the study region, or understanding the impact of wetlands sometimes considered geographically isolated on downstream ecosystems.

Energy and the environment in the Baltic Sea region: A study of cooperative action from the Estonian perspective

NASA Astrophysics Data System (ADS)

Brauer, Alex P.

Due to their geographic proximity and shared natural resources, cooperation on energy-related and environmental issues is particularly important for the nine countries surrounding the Baltic Sea. Currently, two projects are underway that have placed the level of cooperation within the region under the microscope: the environmental management work undertaken by the Helsinki Commission for the Convention on the Protection of the Marine Environment of the Baltic Sea Area (HELCOM) and the Nord Stream pipeline project, which, when completed, will provide the direct transportation of natural gas from Russia to Germany via the Baltic seafloor. Although both have been declared inclusive and decidedly Baltic ventures by some regional actors, reception of the cooperative efforts amongst the littoral Baltic countries has been markedly different. This study addresses these varying reactions by examining Estonia's participation in and subsequent perspectives on the HELCOM and Nord Stream projects. A theoretical framework grounded in the discipline of international relations is utilized to analyze Estonia's role in the projects and its position as a small state in a regional context. The primary areas of focus are how historical experiences and current levels of cooperation in the two endeavors have shaped Estonia's responses and, ultimately, its 'realist' perception of global politics. The study concludes that Estonia appears to have more substantive participation in HELCOM than in the Nord Stream project because of the tendency of states to securitize and, thus, prioritize the energy policy area over the environmental. Estonian foreign policy behavior, however, perpetuates the state-centric and power-centered policy processes that dominate the international political system.

Evidence for a receiver bias underlying female preference for a male mating pheromone in sea lamprey

USGS Publications Warehouse

Buchinger, Tyler J.; Wang, Huiyong; Li, Weiming; Johnson, Nicholas S.

2013-01-01

Receiver bias models suggest that a male sexual signal became exaggerated to match a pre-existing sensory, perceptual or cognitive disposition of the female. Accordingly, these models predict that females of related taxa possessing the ancestral state of signalling evolved preference for the male trait in a non-sexual context. We postulated that female preference for the male-released bile alcohol mating pheromone, 3 keto petromyzonol sulfate (3kPZS), of the sea lamprey (Petromyzon marinus) evolved as a result of a receiver bias. In particular, we propose that migratory silver lamprey (Ichthyomyzon unicuspis), a basal member of the Petromyzontidae, evolved a preference for 3kPZS released by stream-resident larvae as a means of identifying productive habitat for offspring. Larval silver lamprey released 3kPZS at rates sufficient to be detected by migratory lampreys. Females responded to 3kPZS by exhibiting upstream movement behaviours relevant in a migratory context, but did not exhibit proximate behaviours important to mate search and spawning. Male silver lamprey did not release 3kPZS at rates sufficient to be detected by females in natural high-volume stream environments. We infer that female silver lamprey cue onto 3kPZS excreted by stream-resident larvae as a mechanism to locate habitat conducive to offspring survival and that males do not signal with 3kPZS. We suggest that this female preference for a male signal in a non-sexual context represents a bias leading to the sexual signalling observed in sea lamprey.

Evidence of spring formation and subrosion-induced sinkhole development at Ghor Al-Haditha, Jordan, from repeated close-range photogrammetry

NASA Astrophysics Data System (ADS)

Al-Halbouni, Djamil; Eoghan, P. Holohan; Leila, Saberi; Hussam, Alrshdan; Thomas, Walter; Ali, Sawarieh; Torsten, Dahm

2016-04-01

The widespread development of sinkholes and land subsidence poses a major geological hazard to infrastructure, local population, agriculture and industry in the Dead Sea area. For assessment of the key physical factors in this development, repeated photogrammetric and field surveys at Ghor Al-Haditha in Jordan have been undertaken. Recent results provide evidence for subrosion based on strong periodic water flows, as the basic underlying physical process of such land subsidence phenomena. From combined Helikite- and Quatrocopter-based photogrammetric surveys, high resolution Digital Surface Models from October 2014 and October 2015 are compared. Change detection reveals: (1) active subsidence in a hundred metre-scale depression zone, (2) a highly-dynamic spring and canyon system connected with recent sinkhole collapses and (3) the rapid formation of new sinkholes both in alluvium and mud cover sediments. The formation of new sinkholes has been documented locally by means of aerial and field observations during a storm with strong rainfall. A new artesian spring formed in the former Dead Sea bed (mud-flat) at this event. The alluvial sediment load of the stream, a periodic location change of the spring and a connected uphill sinkhole cluster formation provide strong evidence for subrosion of weak material with subsequent underground void collapse. Additionally a documented lake and its' subsequent drainage forming a new canyon reveals the local penetration of the aquiclude behavior of the mud-flat in the major depression area, which can be explained by an under-saturated groundwater flow at a strong hydrostatic gradient. Furthermore an enlargement of the investigated area in the 2015 survey indicates a continuation of subsidence and sinkhole activity towards the North. It reveals several points of emanation of water streams in the mud-flat beneath the alluvial cover and vegetation as an indicator of relatively fresh groundwater inflow. This repeated photogrammetry and field survey confirms the hypothesis of a large-scale, channelized subterranean water flow in a 3d network of interconnected tubes. This subsurface karstic channel network is hence responsible for sinkhole formation and rapid land subsidence at the Ghor Al-Haditha sinkhole area and perhaps elsewhere around the Dead Sea.

New Constraints on Post-LGM WAIS Retreat from the Whales Deep Paleo-ice-stream Trough in Eastern Ross Sea

NASA Astrophysics Data System (ADS)

DeCesare, M.; Bart, P. J.; Rosenheim, B. E.

2016-02-01

New multibeam and seismic data acquired during NBP1502 show that a back-stepping cluster containing at least four grounding zone wedges (GZWs) define a bathymetric saddle on the middle shelf of the Whales Deep paleo-ice-stream trough in eastern Ross Sea. Our synthesis of geophysical data with jumbo piston/kasten cores show that we penetrated diamict, sub-ice shelf and open marine sediments associated with four temporally distinct grounding events. A high number of well-preserved benthic and planktonic foraminifera were found in sediments we interpret to have been deposited in sub-ice shelf and open marine environments. A low number of similarly well-preserved benthic foraminifera were recovered from the underlying ice proximal diamict that was deposited on the GZW foreset. We tentatively propose that the pristine foraminifera are in situ and that these specimens provide a unique opportunity to constrain the retreat of grounded and floating ice from the eastern Ross Sea outer continental shelf. Our ongoing synthesis of new radiocarbon dates, stable isotope (δ18O and δ13C) and element/calcium ratios (e.g., Mg/Ca, B/Ca) will be presented.

Polar versus temperate grounding-line sedimentary systems and marine glacier stability during sea level rise by global warming

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

Powell, R.D.; Pyne, A.R.; Hunter, L.E.

1992-01-01

Marine-ending glaciers may retreat with global warming as sea level rises by ocean thermal expansion. If the sea floor rises by sediment accumulation, then glaciers may not feel the effect of sea level rise. A submersible ROV and other techniques have been used to collect data from temperate and polar glaciers to compare sediment production and mass balance of their grounding-line systems. Temperature Alaskan valley glaciers flow at about 0.2--2 km/a and have high volumes of supraglacial, englacial and subglacial debris. However, most sediment contributed to the base of their tidewater cliffs comes from subglacial streams or squeezing out subglacialmore » sediment and pushing it with other marine sediment into a morainal bank. Blue Glacier, a thin, locally fed polar glacier in Antarctica, flows slowly and has minimal glacial debris. The grounding-line system at the tidewater cliff is a morainal bank that forms solely by pushing of marine sediment. An Antarctic polar outlet glacier, Mackay Glacier, terminating as a floating glacier-tongue, has similar volumes of basal debris to Alaskan temperature glaciers and flows at 250 m/a. However, no subglacial streams issued from Mackay's grounding line and all sedimentation was by rockfall and grainfall rainout from seawater undermelt of the tongue. A grounding-line wedge of glacimarine diamicton is deposited over subglacial (lodgement ) till. Although Antarctic grounding-line accumulation rates are three orders of magnitude smaller than Alaskan rates, both are capable of compensating for predicted rises in sea level by thermal heating from global warming.« less

In situ observations of Arctic cloud properties across the Beaufort Sea marginal ice zone

NASA Astrophysics Data System (ADS)

Corr, C.; Moore, R.; Winstead, E.; Thornhill, K. L., II; Crosbie, E.; Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Martin, R.; Shook, M.; Corbett, J.; Smith, W. L., Jr.; Anderson, B. E.

2016-12-01

Clouds play an important role in Arctic climate. This is particularly true over the Arctic Ocean where feedbacks between clouds and sea-ice impact the surface radiation budget through modifications of sea-ice extent, ice thickness, cloud base height, and cloud cover. This work summarizes measurements of Arctic cloud properties made aboard the NASA C-130 aircraft over the Beaufort Sea during ARISE (Arctic Radiation - IceBridge Sea&Ice Experiment) in September 2014. The influence of surface-type on cloud properties is also investigated. Specifically, liquid water content (LWC), droplet concentrations, and droplet size distributions are compared for clouds sampled over three distinct regimes in the Beaufort Sea: 1) open water, 2) the marginal ice zone, and 3) sea-ice. Regardless of surface type, nearly all clouds intercepted during ARISE were liquid-phase clouds. However, differences in droplet size distributions and concentrations were evident for the surface types; clouds over the MIZ and sea-ice generally had fewer and larger droplets compared to those over open water. The potential implication these results have for understanding cloud-surface albedo climate feedbacks in Arctic are discussed.

A new bed elevation model for the Weddell Sea sector of the West Antarctic Ice Sheet

NASA Astrophysics Data System (ADS)

Jeofry, Hafeez; Ross, Neil; Corr, Hugh F. J.; Li, Jilu; Morlighem, Mathieu; Gogineni, Prasad; Siegert, Martin J.

2018-04-01

We present a new digital elevation model (DEM) of the bed, with a 1 km gridding, of the Weddell Sea (WS) sector of the West Antarctic Ice Sheet (WAIS). The DEM has a total area of ˜ 125 000 km2 covering the Institute, Möller and Foundation ice streams, as well as the Bungenstock ice rise. In comparison with the Bedmap2 product, our DEM includes new aerogeophysical datasets acquired by the Center for Remote Sensing of Ice Sheets (CReSIS) through the NASA Operation IceBridge (OIB) program in 2012, 2014 and 2016. We also improve bed elevation information from the single largest existing dataset in the region, collected by the British Antarctic Survey (BAS) Polarimetric radar Airborne Science Instrument (PASIN) in 2010-2011, from the relatively crude measurements determined in the field for quality control purposes used in Bedmap2. While the gross form of the new DEM is similar to Bedmap2, there are some notable differences. For example, the position and size of a deep subglacial trough (˜ 2 km below sea level) between the ice-sheet interior and the grounding line of the Foundation Ice Stream have been redefined. From the revised DEM, we are able to better derive the expected routing of basal water and, by comparison with that calculated using Bedmap2, we are able to assess regions where hydraulic flow is sensitive to change. Given the potential vulnerability of this sector to ocean-induced melting at the grounding line, especially in light of the improved definition of the Foundation Ice Stream trough, our revised DEM will be of value to ice-sheet modelling in efforts to quantify future glaciological changes in the region and, from this, the potential impact on global sea level. The new 1 km bed elevation product of the WS sector can be found at https://doi.org/10.5281/zenodo.1035488.

Simulated effects of development on regional ground-water/surface-water interactions in the northern Coastal Plain of New Jersey

NASA Astrophysics Data System (ADS)

Pucci, Amleto A.; Pope, Daryll A.

1995-05-01

Stream flow in the Coastal Plain of New Jersey is primarily controlled by ground-water discharge. Ground-water flow in a 400 square mile area (1035 km 2) of the Potomac-Raritan-Magothy aquifer system (PRMA) in the northern Coastal Plain of New Jersey was simulated to examine development effects on water resources. Simulations showed that historical development caused significant capture of regional ground-water discharge to streams and wetlands. The Cretaceous PRMA primarily is composed of fine to coarse sand, clays and silts which form the Upper and Middle aquifers and their confining units. The aquifer outcrops are the principal areas of recharge and discharge for the regional flow system and have many traversing streams and surface-water bodies. A quasi-three-dimensional numerical model that incorporated ground-water/surface-water interactions and boundary flows from a larger regional model was used to represent the PRMA. To evaluate the influence of ground-water development on interactions in different areas, hydrogeologically similar and contiguous model stream cells were aggregated as 'stream zones'. The model representation of surface-water and ground-water interaction was limited in the areas of confining unit outcrops and because of this, simulated ground-water discharge could not be directly compared with base flow. Significant differences in simulated ground-water and surface-water interactions between the predevelopment and developed system, include; (1) redistribution of recharge and discharge areas; (2) reduced ground-water discharge to streams. In predevelopment, the primary discharge for the Upper and Middle aquifers is to low-lying streams and wetlands; in the developed system, the primary discharge is to ground-water withdrawals. Development reduces simulated ground-water discharge to streams in the Upper Aquifer from 61.4 to 10% of the Upper Aquifer hydrologic budget (28.9%, if impounded stream flow is included). Ground-water discharge to streams in the Middle Aquifer decreases from 80.0 to 22% of the Middle Aquifer hydrologic budget. The utility of assessing ground-water/surface-water interaction in a regional hydrogeologic system by simulation responses to development is demonstrated and which can compensate for lack of long-term stream-gaging data in determining management decisions.

Increasing persistent haze in Beijing: potential impacts of weakening East Asian winter monsoons associated with northwestern Pacific sea surface temperature trends

NASA Astrophysics Data System (ADS)

Pei, Lin; Yan, Zhongwei; Sun, Zhaobin; Miao, Shiguang; Yao, Yao

2018-03-01

Over the past decades, Beijing, the capital city of China, has encountered increasingly frequent persistent haze events (PHE). While the increased pollutant emissions are considered as the most important reason, changes in regional atmospheric circulations associated with large-scale climate warming also play a role. In this study, we find a significant positive trend of PHE in Beijing for the winters from 1980 to 2016 based on updated daily observations. This trend is closely related to an increasing frequency of extreme anomalous southerly episodes in North China, a weakened East Asian trough in the mid-troposphere and a northward shift of the East Asian jet stream in the upper troposphere. These conditions together depict a weakened East Asian winter monsoon (EAWM) system, which is then found to be associated with an anomalous warm, high-pressure system in the middle-lower troposphere over the northwestern Pacific. A practical EAWM index is defined as the seasonal meridional wind anomaly at 850 hPa in winter over North China. Over the period 1900-2016, this EAWM index is positively correlated with the sea surface temperature anomalies over the northwestern Pacific, which indicates a wavy positive trend, with an enhanced positive phase since the mid-1980s. Our results suggest an observation-based mechanism linking the increase in PHE in Beijing with large-scale climatic warming through changes in the typical regional atmospheric circulation.

The SeaFlux Turbulent Flux Dataset Version 1.0 Documentation

NASA Technical Reports Server (NTRS)

Clayson, Carol Anne; Roberts, J. Brent; Bogdanoff, Alec S.

2012-01-01

Under the auspices of the World Climate Research Programme (WCRP) Global Energy and Water cycle EXperiment (GEWEX) Data and Assessment Panel (GDAP), the SeaFlux Project was created to investigate producing a high-resolution satellite-based dataset of surface turbulent fluxes over the global oceans. The most current release of the SeaFlux product is Version 1.0; this represents the initial release of turbulent surface heat fluxes, associated near-surface variables including a diurnally varying sea surface temperature.

An alternative to reduction of surface pressure to sea level

NASA Technical Reports Server (NTRS)

Deardorff, J. W.

1982-01-01

The pitfalls of the present method of reducing surface pressure to sea level are reviewed, and an alternative, adjusted pressure, P, is proposed. P is obtained from solution of a Poisson equation over a continental region, using the simplest boundary condition along the perimeter or coastline where P equals the sea level pressure. The use of P would avoid the empiricisms and disadvantages of pressure reduction to sea level, and would produce surface pressure charts which depict the true geostrophic wind at the surface.

Visible and Thermal Imaging of Sea Ice and Open Water from Coast Guard Arctic Domain Awareness Flights

DTIC Science & Technology

2014-09-30

dropsondes, micro- aircraft), cloud top/base heights Arctic Ocean Surface Temperature project Steele Buoy drops for SLP , SST, SSS, & surface velocity...Colón & Vancas (NIC) Drop buoys for SLP , temperature and surface velocity Waves & Fetch in the MIZ Thompson SWIFTS buoys measuring wave energy...Expendable CTD, AXCP= Air Expendable Current Profiler, SLP = Sea Level atmospheric Pressure, SST= Seas Surface Temperature, A/C= aircraft, FSD= Floe Size Distribution, SIC=Sea Ice Concentration

Methods and apparatuses for cutting, abrading, and drilling

DOEpatents

Bingham, Dennis N.; Swainston, Richard C.; Palmer, Gary L.; Ferguson, Russell L.

2001-01-01

Methods and apparatuses for treating a surface of a work piece are described. In one implementation, a laser delivery subsystem is configured to direct a laser beam toward a treatment zone on a work surface. A cryogenic material delivery subsystem is operably coupled with the laser delivery subsystem and is configured to direct a stream comprising cryogenic material toward the treatment zone. Both the laser beam and stream cooperate to treat material of the work surface within the treatment zone. In one aspect, a nozzle assembly provides the laser beam and stream of cryogenic material along a common flow axis. In another aspect, the laser beam and stream are provided along different axes.

Free stream capturing in fluid conservation law for moving coordinates in three dimensions

NASA Technical Reports Server (NTRS)

Obayashi, Shigeru

1991-01-01

The free-stream capturing technique for both the finite-volume (FV) and finite-difference (FD) framework is summarized. For an arbitrary motion of the grid, the FV analysis shows that volumes swept by all six surfaces of the cell have to be computed correctly. This means that the free-stream capturing time-metric terms should be calculated not only from a surface vector of a cell at a single time level, but also from a volume swept by the cell surface in space and time. The FV free-stream capturing formulation is applicable to the FD formulation by proper translation from an FV cell to an FD mesh.

An atlas of monthly mean distributions of GEOSAT sea surface height, SSMI surface wind speed, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1988

NASA Technical Reports Server (NTRS)

Halpern, D.; Zlotnicki, V.; Newman, J.; Brown, O.; Wentz, F.

1991-01-01

Monthly mean global distributions for 1988 are presented with a common color scale and geographical map. Distributions are included for sea surface height variation estimated from GEOSAT; surface wind speed estimated from the Special Sensor Microwave Imager on the Defense Meteorological Satellite Program spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer on NOAA spacecrafts; and the Cartesian components of the 10m height wind vector computed by the European Center for Medium Range Weather Forecasting. Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

An Evaluation of Sea Surface Temperature as Measured by the Nimbus 1 High Resolution Infrared Radiometer

NASA Technical Reports Server (NTRS)

Allison, Lewis J.; Kennedy, James S.

1967-01-01

An analysis of Nimbus I HRIR data over various parts of the world indicated limited success in deriving sea surface temperatures to within 3 to 6 K of aircraft radiation measurements (8- 13 microns) and synoptic-climatological ship sea surface temperature data. The areas studied included the east, west and Gulf coasts of the United States, West Greenland, Nova Scotia, southern Japan, the eastern Mediterranean Sea, Caspian Sea, Persian Gulf, and the Indian Ocean. At night, thin clouds which may fill the radiometer's field of view make it difficult to interpret the absolute values of derived sea surface temperature. During the daytime, the HRIR data is unusable for oceanographic temperature analysis because the contamination by reflected solar radiation mixes with the emitted radiation. Future satellite instrumentation, consisting of a HFUR radiometer (10-11 microns) when used in conjunction with television. data, will delineate cloud free ocean areas and permit the daily derivation of sea surface temperatures from approximately 10 to 30 Percent of the world's oceanic regions.

Stream Temperature Estimation From Thermal Infrared Images

NASA Astrophysics Data System (ADS)

Handcock, R. N.; Kay, J. E.; Gillespie, A.; Naveh, N.; Cherkauer, K. A.; Burges, S. J.; Booth, D. B.

2001-12-01

Stream temperature is an important water quality indicator in the Pacific Northwest where endangered fish populations are sensitive to elevated water temperature. Cold water refugia are essential for the survival of threatened salmon when events such as the removal of riparian vegetation result in elevated stream temperatures. Regional assessment of stream temperatures is limited by sparse sampling of temperatures in both space and time. If critical watersheds are to be properly managed it is necessary to have spatially extensive temperature measurements of known accuracy. Remotely sensed thermal infrared (TIR) imagery can be used to derive spatially distributed estimates of the skin temperature (top 100 nm) of streams. TIR imagery has long been used to estimate skin temperatures of the ocean, where split-window techniques have been used to compensate for atmospheric affects. Streams are a more complex environment because 1) most are unresolved in typical TIR images, and 2) the near-bank environment of stream corridors may consist of tall trees or hot rocks and soils that irradiate the stream surface. As well as compensating for atmospheric effects, key problems to solve in estimating stream temperatures include both subpixel unmixing and multiple scattering. Additionally, fine resolution characteristics of the stream surface such as evaporative cooling due to wind, and water surface roughness, will effect measurements of radiant skin temperatures with TIR devices. We apply these corrections across the Green River and Yakima River watersheds in Washington State to assess the accuracy of remotely sensed stream surface temperature estimates made using fine resolution TIR imagery from a ground-based sensor (FLIR), medium resolution data from the airborne MASTER sensor, and coarse-resolution data from the Terra-ASTER satellite. We use linear spectral mixture analysis to isolate the fraction of land-leaving radiance originating from unresolved streams. To compensate the data for atmospheric effects we combine radiosonde profiles with a physically based radiative transfer model (MODTRAN) and an in-scene relative correction adapted from the ISAC algorithm. Laboratory values for water emissivities are used as a baseline estimate of stream emissivities. Emitted radiance reflected by trees in the stream near-bank environment is estimated from the height and canopy temperature, using a radiosity model.

Stream structure at low flow: biogeochemical patterns in intermittent streams over space and time

NASA Astrophysics Data System (ADS)

MacNeille, R. B.; Lohse, K. A.; Godsey, S.; McCorkle, E. P.; Parsons, S.; Baxter, C.

2017-12-01

Climate change in the western United States is projected to lead to earlier snowmelt, increasing fire risk and potentially transitioning perennial streams to intermittent ones. Differences between perennial and intermittent streams, especially the temporal and spatial patterns of carbon and nutrient dynamics during periods of drying, are understudied. We examined spatial and temporal patterns in surface water biogeochemistry during a dry (2016) and a wet (2017) water year in southwest Idaho. We hypothesized that as streams dry, carbon concentrations would increase due to evapoconcentration and/or increased in-stream production, and that the heterogeneity of constituents within each stream would increase. We expected these patterns to differ in a high water year compared to a low water year due to algae scour. Finally, we expected that the spatial heterogeneity of biogeochemistry would decrease with time following fire. To test these hypotheses, in 2016 we collected surface water samples at 50 meter intervals from two intermittent headwater streams over 2,500 meter reaches in April, May, and June. One stream is burned and one remains unburned. In 2017, we collected surface water at the 50, 25 and 10 meter intervals from each stream once during low flow. 2016 results showed average concentrations of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) increased 3-fold from April to June in the burned site compared to the unburned site. Interestingly, average concentrations of total nitrogen (TN) dropped substantially for the burned site over these three months, but only decreased slightly for the unburned site over the same time period. Between wet and dry water years, we observed a decrease in the spatial heterogeneity as measured by the standard deviation (SD) in conductivity at 50 meter intervals; the burned stream had a SD of 23.08 in 2016 and 11.40 in 2017 whereas the unburned stream had similar SDs. We conclude that the burned stream experienced more inter and intra-annual surface water change in chemistry patterns than did the unburned stream.

40 CFR 401.11 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal... interstate commerce; and intrastate lakes, rivers, and streams which are utilized for industrial purposes by..., person, territorial seas, contiguous zone, biological monitoring, schedule of compliance, and industrial...

40 CFR 401.11 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal... interstate commerce; and intrastate lakes, rivers, and streams which are utilized for industrial purposes by..., person, territorial seas, contiguous zone, biological monitoring, schedule of compliance, and industrial...

40 CFR 401.11 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal... interstate commerce; and intrastate lakes, rivers, and streams which are utilized for industrial purposes by..., person, territorial seas, contiguous zone, biological monitoring, schedule of compliance, and industrial...

The Impact of Moisture Intrusions from Lower Latitudes on Arctic Net Surface Radiative Fluxes and Sea Ice Growth in Fall and Winter

NASA Astrophysics Data System (ADS)

Hegyi, B. M.; Taylor, P. C.

2017-12-01

The fall and winter seasons mark an important period in the evolution of Arctic sea ice, where energy is transferred away from the surface to facilitate the cooling of the surface and the growth of Arctic sea ice extent and thickness. Climatologically, these seasons are characterized by distinct periods of increased and reduced surface cooling and sea ice growth. Periods of reduced sea ice growth and surface cooling are associated with cloudy conditions and the transport of warm and moist air from lower latitudes, termed moisture intrusions. In the research presented, we explore the regional and Arctic-wide impact of moisture intrusions on the surface net radiative fluxes and sea ice growth for each fall and winter season from 2000/01-2015/16, utilizing MERRA2 reanalysis data, PIOMAS sea ice thickness data, and daily CERES radiative flux data. Consistent with previous studies, we find that positive anomalies in downwelling longwave surface flux are associated with increased temperature and water vapor content in the atmospheric column contained within the moisture intrusions. Interestingly, there are periods of increased downwelling LW flux anomalies that persist for one week or longer (i.e. longer than synoptic timescales) that are associated with persistent poleward flux of warm, moist air from lower latitudes. These persistent anomalies significantly reduce the regional growth of Arctic sea ice, and may in part explain the interannual variability of fall and winter Arctic sea ice growth.

Modulation of Sea Ice Melt Onset and Retreat in the Laptev Sea by the Timing of Snow Retreat in the West Siberian Plain

NASA Astrophysics Data System (ADS)

Crawford, A. D.; Stroeve, J.; Serreze, M. C.; Rajagopalan, B.; Horvath, S.

2017-12-01

As much of the Arctic Ocean transitions to ice-free conditions in summer, efforts have increased to improve seasonal forecasts of not only sea ice extent, but also the timing of melt onset and retreat. This research investigates the potential of regional terrestrial snow retreat in spring as a predictor for subsequent sea ice melt onset and retreat in Arctic seas. One pathway involves earlier snow retreat enhancing atmospheric moisture content, which increases downwelling longwave radiation over sea ice cover downstream. Another pathway involves manipulation of jet stream behavior, which may affect the sea ice pack via both dynamic and thermodynamic processes. Although several possible connections between snow and sea ice regions are identified using a mutual information criterion, the physical mechanisms linking snow retreat and sea ice phenology are most clearly exemplified by variability of snow retreat in the West Siberian Plain impacting melt onset and sea ice retreat in the Laptev Sea. The detrended time series of snow retreat in the West Siberian Plain explains 26% of the detrended variance in Laptev Sea melt onset (29% for sea ice retreat). With modest predictive skill and an average time lag of 53 (88) days between snow retreat and sea ice melt onset (retreat), West Siberian Plains snow retreat is useful for refining seasonal sea ice predictions in the Laptev Sea.

Effects of land use and seasonality on stream water quality in a small tropical catchment: The headwater of Córrego Água Limpa, São Paulo (Brazil).

PubMed

Rodrigues, Valdemir; Estrany, Joan; Ranzini, Mauricio; de Cicco, Valdir; Martín-Benito, José Mª Tarjuelo; Hedo, Javier; Lucas-Borja, Manuel E

2018-05-01

Stream water quality is controlled by the interaction of natural and anthropogenic factors over a range of temporal and spatial scales. Among these anthropogenic factors, land cover changes at catchment scale can affect stream water quality. This work aims to evaluate the influence of land use and seasonality on stream water quality in a representative tropical headwater catchment named as Córrego Água Limpa (Sao Paulo, Brasil), which is highly influenced by intensive agricultural activities and urban areas. Two systematic sampling approach campaigns were implemented with six sampling points along the stream of the headwater catchment to evaluate water quality during the rainy and dry seasons. Three replicates were collected at each sampling point in 2011. Electrical conductivity, nitrates, nitrites, sodium superoxide, Chemical Oxygen Demand (DQO), colour, turbidity, suspended solids, soluble solids and total solids were measured. Water quality parameters differed among sampling points, being lower at the headwater sampling point (0m above sea level), and then progressively higher until the last downstream sampling point (2500m above sea level). For the dry season, the mean discharge was 39.5ls -1 (from April to September) whereas 113.0ls -1 were averaged during the rainy season (from October to March). In addition, significant temporal and spatial differences were observed (P<0.05) for the fourteen parameters during the rainy and dry period. The study enhance significant relationships among land use and water quality and its temporal effect, showing seasonal differences between the land use and water quality connection, highlighting the importance of multiple spatial and temporal scales for understanding the impacts of human activities on catchment ecosystem services. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrology of area 59, northern Great Plains and Rocky Mountain coal provinces, Colorado and Wyoming

USGS Publications Warehouse

Gaggiani, Neville G.; Britton, Linda J.; Minges, Donald R.; Kilpatrick, F.A.; Parker, Randolph S.; Kircher, James E.

1987-01-01

Hydrologic information and analysis aid in decisions to lease federally owned coal and to prepare necessary Environmental Assessments and Impact Study reports. This need has become even more critical with the enactment of Public Law 95-87, the "Surface Mining Control and Reclamation Act of 1977." This act requires an appropriate regulatory agency to issue permits, based on the review of permit-application data to assess hydrologic impacts. This report, which partially fulfills this requirement, is one in a series of nationwide coal province reports that present information thematically, through the use of a brief text and accompanying maps, graphs, charts, or other illustrations for single hydrologic topics. The report broadly characterizes the hydrology of Area 59 in north-central Colorado and southeastern Wyoming.The report area, located within the South Platte River basin, covers a 16,000-square-mile area of diverse geology, topography, and climate. This diversity results in contrasting hydrologic characteristics.The South Platte River, the major stream in the area, and most of its tributaries originate in granitic mountains and flow into and through the sedimentary rocks of the Great Plains. Altitudes range from less than 5,000 feet to more than 14,000 feet above sea level. Precipitation in the mountains may exceed 40 inches annually, much of it during the winter, and produces deep snowpacks. Snowmelt during the spring and summer produces most streamflow. Transmountain diversion of water from the streams on the western slope of the mountains also adds to the streamflow. Precipitation in the plains is as little as 10 inches annually. Streams that originate in the plains are ephemeral.Streamflow quality is best in the mountains, where dissolved-solids concentrations are generally small. Concentrations increase in the plains as streams flow through sedimentary basins, and as urbanization and irrigation increase. The quality of some mountain streams is affected by drainage from previous metalmining areas, as indicated by greater trace-element concentrations and smaller pH values. However, the large trace-element concentrations decrease rapidly downstream from the metal-mining areas. Because the climate is semiarid in most of the area, the soils are not adequately leached; therefore, flows in ephemeral streams usually have larger concentrations of dissolved solids than flows in perennial streams.Ground water is available throughout the area; yields range from less than 0.1 gallons per minute in the fractured granite aquifer in the mountains to more than 2,000 gallons per minute in the alluvial aquifer of the South Platte River valley. Major bedrock aquifers in order of decreasing age are the Laramie-Fox Hills, Arapahoe, Denver, and Dawson; these aquifers are used for municipal, domestic, and livestock supplies. Alluvial aquifers supply the high-yield irrigation wells.The best quality ground water is found at the center of the major bedrock aquifers, where dissolved-solids concentrations are less than 200 milligrams per liter. The poorest-quality water is usually found near the edges of these aquifers. Water in the coal-bearing Laramie and Denver Formations is locally affected by coal deposits, causing dissolved-solids concentrations to be relatively large.Only one coal mine is now operating in Area 59, the Coors Energy Company surface coal mine, which produced 100,000 short tons of subbituminous coal from the Upper Cretaceous Laramie Formation in 1982. Past coal-mining operations removed more than 130 million tons of coal and lignite from Area 59,99 percent of which came from underground mines. The largest coal production was in Weld and Boulder Counties, Colorado.Hydrologic problems related to surface mining are erosion, sedimentation, decline in water levels, disruption of aquifers, and degradation of water quality. Because the semiarid mine areas have very little runoff, and the major streams have large buffer and dilution capacities, the effects of mining on surface water is minimal. However, effects on ground water may be much more severe and long-lasting.

Observing the seasonal cycle of the upper ocean in the Ross Sea, Antarctica, with autonomous profiling floats

NASA Astrophysics Data System (ADS)

Porter, D. F.; Springer, S. R.; Padman, L.; Fricker, H. A.; Bell, R. E.

2017-12-01

The upper layers of the Southern Ocean where it meets the Antarctic ice sheet undergoes a large seasonal cycle controlled by surface radiation and by freshwater fluxes, both of which are strongly influenced by sea ice. In regions where seasonal sea ice and icebergs limit use of ice-tethered profilers and conventional moorings, autonomous profiling floats can sample the upper ocean. The deployment of seven Apex floats (by sea) and six ALAMO floats (by air) provides unique upper ocean hydrographic data in the Ross Sea close to the Ross Ice Shelf front. A novel choice of mission parameters - setting parking depth deeper than the seabed - limits their drift, allowing us to deploy the floats close to the ice shelf front, while sea ice avoidance algorithms allow the floats to to sample through winter under sea ice. Hydrographic profiles show the detailed development of the seasonal mixed layer close to the Ross front, and interannual variability of the seasonal mixed layer and deeper water masses on the central Ross Sea continental shelf. After the sea ice breakup in spring, a warm and fresh surface mixed layer develops, further warming and deepening throughout the summer. The mixed layer deepens, with maximum temperatures exceeding 0ºC in mid-February. By March, the surface energy budget becomes negative and sea ice begins to form, creating a cold, saline and dense surface layer. Once these processes overcome the stable summer stratification, convection erodes the surface mixed layer, mixing some heat downwards to deeper layers. There is considerable interannual variability in the evolution and strength of the surface mixed layer: summers with shorter ice-free periods result in a cooler and shallower surface mixed layer, which accumulates less heat than the summers with longer ice-free periods. Early ice breakup occurred in all floats in 2016/17 summer, enhancing the absorbed solar flux leading to a warmer surface mixed layer. Together, these unique measurements from autonomous profilers provide insight into the hydrographic state of the Ross Sea at the start of the spring period of sea-ice breakup, and how ocean mixing and sea ice interact to initiate the summer open-water season.

The ecology and biogeochemistry of stream biofilms.

PubMed

Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

2016-04-01

Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

Copper in the sediment and sea surface microlayer near a fallowed, open-net fish farm.

PubMed

Loucks, Ronald H; Smith, Ruth E; Fisher, Clyde V; Fisher, E Brian

2012-09-01

Sediment and sea surface microlayer samples near an open-net salmon farm in Nova Scotia, were analysed for copper. Copper is a constituent of the feed and is an active ingredient of anti-foulants. The salmon farm was placed in fallow after 15 years of production. Sampling was pursued over 27 months. Elevated copper concentrations in the sediments indicated the farm site as a source. Bubble flotation due to gas-emitting sediments from eutrophication is a likely process for accumulating copper in the sea surface microlayer at enriched concentrations. Elevated and enriched concentrations in the sea surface microlayer over distance from the farm site led, as a result of wind-drift, to an enlarged farm footprint. The levels of copper in both sediments and sea surface microlayer exceeded guidelines for protection of marine life. Over the 27 months period, copper levels persisted in the sediments and decreased gradually in the sea surface microlayer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Radar sea reflection for low-e targets

NASA Astrophysics Data System (ADS)

Chow, Winston C.; Groves, Gordon W.

1998-09-01

Modeling radar signal reflection from a wavy sea surface uses a realistic characteristic of the large surface features and parameterizes the effect of the small roughness elements. Representation of the reflection coefficient at each point of the sea surface as a function of the Specular Deviation Angle is, to our knowledge, a novel approach. The objective is to achieve enough simplification and retain enough fidelity to obtain a practical multipath model. The 'specular deviation angle' as used in this investigation is defined and explained. Being a function of the sea elevations, which are stochastic in nature, this quantity is also random and has a probability density function. This density function depends on the relative geometry of the antenna and target positions, and together with the beam- broadening effect of the small surface ripples determined the reflectivity of the sea surface at each point. The probability density function of the specular deviation angle is derived. The distribution of the specular deviation angel as function of position on the mean sea surface is described.

Sun-stirred Kraken Mare: Circulation in Titan's seas induced by solar heating and methane precipitation

NASA Astrophysics Data System (ADS)

Tokano, T.; Lorenz, R. D.

2015-10-01

Density-driven circulation in Titan's seas forced by solar heating and methane evaporation/precipitation is simulated by an ocean circulation model. If the sea is transparent to sunlight, solar heating can induce anti-clockwise gyres near the sea surface and clockwise gyres near the sea bottom. The gyres are in geostrophic balance between the radially symmetric pressure gradient force and Coriolis force. If instead the sea is turbid and most sunlight is absorbed near the sea surface, the sea gets stratified in warm seasons and the circulation remains weak. Strong summer precipitation at high latitudes causes compositional stratification and increase of the nearsurface methane mole fraction towards the north pole. The resultant latitudinal density contrast drives a meridional overturning with equatorward currents near the sea surface and poleward currents near the sea bottom. Weak precipitation induces gyres rather than meridional overturning.

Liquid additives for particulate emissions control

DOEpatents

Durham, Michael Dean; Schlager, Richard John; Ebner, Timothy George; Stewart, Robin Michele; Hyatt, David E.; Bustard, Cynthia Jean; Sjostrom, Sharon

1999-01-01

The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Effects of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) on pH, net oxygen production, and respiration by algae

USGS Publications Warehouse

Scholefield, Ronald J.; Fredricks, Kim T.; Slaght, Karen S.; Seelye, James G.

1999-01-01

The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) has been used in the United States and Canada for more than 35 years to control larval sea lampreys (Petromyzon marinus) in tributaries of the Great Lakes. Occasionally, during stream treatments with TFM, nontarget-fish mortality reaches unacceptable levels. These losses could be due to the presence of sensitive fish species, excess TFM, or a combination of factors that influence the toxicity of TFM, such as delays in daily stream reaeration by algae resulting in extended periods of low pH and low dissolved oxygen (DO). We determined the effects of a broad range of TFM concentrations on net DO production and respiration by two species of algae, in two culture media (high alkalinity and low alkalinity). The pH and DO in cultures of Chlorella pyrenoidosa and Selenastrum capricornutum were recorded at time zero and again after a 9-h exposure to TFM under either lighted or dark conditions. Algal cultures exposed to TFM concentrations typical of those used to control sea lampreys in streams showed only small changes in pH (<0.1) and small reductions in DO (about 8% in lighted conditions and 11% in dark conditions). Changes in pH and DO of this magnitude probably do not change the efficacy of TFM or cause nontarget fish mortality if algae are the predominant photosynthetic organisms in the stream.

Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

PubMed Central

Ma, Xiaohui; Chang, Ping; Saravanan, R.; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

2015-01-01

High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy–atmosphere interaction in forecast and climate models. PMID:26635077

Water Resources Data, Florida, Water Year 2003 Volume 2B: South Florida Ground Water

USGS Publications Warehouse

Prinos, S.; Irvin, R.; Byrne, M.

2004-01-01

Water resources data for 2003 water year in Florida consists of continuous or daily discharge for 385 streams, periodic discharge for 13 streams, continuous or daily stage for 255 streams, periodic stage for 13 stream, peak discharge for 36 streams, and peak stage for 36 streams, continuous or daily elevations for 13 lakes, periodic elevations for 46 lakes, continuous ground-water levels for 441 wells, periodic ground-water levels for 1227 wells, quality of water data for 133 surface-water sites, and 308 wells. The data for South Florida included continuous or daily discharge for 72 streams, continuous or daily stage for 50 streams, no peak stage discharge for streams, 1 continuous elevation for lake, continuous ground-water levels for 237 wells, periodic ground-water levels for 248 wells, water quality for 25 surface-water sites, and 161 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperation with local, state, and federal agencies in Florida.

Nutrient sampling slam: high resolution surface-water sampling in streams reveals patterns in groundwater chemistry and flow paths

EPA Science Inventory

The groundwater–surface water interface (GSWI), consisting of shallow groundwater adjacent to stream channels, is a hot spot for nitrogen removal processes, a storage zone for other solutes, and a target for restoration activities. Characterizing groundwater-surface water intera...

A modelling study of the influence of anomalous wind forcing over the Barents Sea on the Atlantic water flow to the Arctic Ocean in the period 1979-2004

NASA Astrophysics Data System (ADS)

Marciniak, Jakub; Schlichtholz, Pawel; Maslowski, Wieslaw

2016-04-01

Arctic climate system is influenced by oceanic heat transport with the Atlantic water (AW) streaming towards the Arctic Ocean in two branches, through the deep Fram Strait and the shallow Barents Sea. In Fram Strait, the AW submerges below the Polar surface water and then flows cyclonically along the margin of the Arctic Ocean as a subsurface water mass in the Arctic Slope Current. In contrast to the Fram Strait branch, which is the major source of heat for the Arctic Ocean, most of the heat influx to the Barents Sea through the Barents Sea opening (BSO) is passed to the atmosphere. Only cold remnants of AW outflow to the Arctic Ocean through the northeastern gate of the Barents Sea. Some AW entering the Barents Sea recirculates westward, contributing to an outflow from the Barents Sea through the BSO along the shelf slope south of Bear Island, in the Bear Island Slope Current. Even though the two-branched AW flow toward the Arctic Ocean has been known for more than a century, little is known about co-variability of heat fluxes in the two branches, its mechanisms and climatic implications. Recent studies indicate that the Bear Island Slope Current may play a role in this co-variability. Here, co-variability of the flow through the BSO and Fram Strait is investigated using a pan-Arctic coupled ice-ocean hindcast model run for the period 1979-2004 and forced with daily atmospheric data from the ECMWF. Significant wintertime co-variability between the volume transport in the Bear Island and Arctic slope currents and its link to wind forcing over the Barents Sea is confirmed. It is found that the volume transports in these currents are, however, not correlated in the annual mean and that the wintertime co-variability of these currents has no immediate effect on either the net heat flux through the BSO or the net heat flux divergence in the Barents Sea. It is shown that the main climatic effect of wind forcing over the northern Barents Sea shelf is to induce temperature anomalies in the Murman/West Novaya Zemlya current system on the eastern side of the Barents Sea. These anomalies affect sea ice in the eastern Barents Sea 1-3 months later, but are not completely lost on the interactions with the sea ice and local atmosphere. Statistically significant subsurface temperature anomalies driven by anomalous winds over the Barents Sea join, on their exit to the Arctic Ocean through St. Anna Trough, the Arctic Slope Current, in which they persist for several years.

The history and future trends of ocean warming-induced gas hydrate dissociation in the SW Barents Sea

NASA Astrophysics Data System (ADS)

Vadakkepuliyambatta, Sunil; Chand, Shyam; Bünz, Stefan

2017-01-01

The Barents Sea is a major part of the Arctic where the Gulf Stream mixes with the cold Arctic waters. Late Cenozoic uplift and glacial erosion have resulted in hydrocarbon leakage from reservoirs, evolution of fluid flow systems, shallow gas accumulations, and hydrate formation throughout the Barents Sea. Here we integrate seismic data observations of gas hydrate accumulations along with gas hydrate stability modeling to analyze the impact of warming ocean waters in the recent past and future (1960-2060). Seismic observations of bottom-simulating reflectors (BSRs) indicate significant thermogenic gas input into the hydrate stability zone throughout the SW Barents Sea. The distribution of BSR is controlled primarily by fluid flow focusing features, such as gas chimneys and faults. Warming ocean bottom temperatures over the recent past and in future (1960-2060) can result in hydrate dissociation over an area covering 0.03-38% of the SW Barents Sea.

Emissions of carbon dioxide and methane from a headwater stream network of interior Alaska

USGS Publications Warehouse

Crawford, John T.; Striegl, Robert G.; Wickland, Kimberly P.; Dornblaser, Mark M.; Stanley, Emily H.

2013-01-01

Boreal ecosystems store significant quantities of organic carbon (C) that may be vulnerable to degradation as a result of a warming climate. Despite their limited coverage on the landscape, streams play a significant role in the processing, gaseous emission, and downstream export of C, and small streams are thought to be particularly important because of their close connection with the surrounding landscape. However, ecosystem carbon studies do not commonly incorporate the role of the aquatic conduit. We measured carbon dioxide (CO2) and methane (CH4) concentrations and emissions in a headwater stream network of interior Alaska underlain by permafrost to assess the potential role of stream gas emissions in the regional carbon balance. First-order streams exhibited the greatest variability in fluxes of CO2 and CH4,and the greatest mean pCO2. High-resolution time series of stream pCO2 and discharge at two locations on one first-order stream showed opposing pCO2 responses to storm events, indicating the importance of hydrologic flowpaths connecting CO2-rich soils with surface waters. Repeated longitudinal surveys on the stream showed consistent areas of elevated pCO2 and pCH4, indicative of discrete hydrologic flowpaths delivering soil water and groundwater having varying chemistry. Up-scaled basin estimates of stream gas emissions suggest that streams may contribute significantly to catchment-wide CH4 emissions. Overall, our results indicate that while stream-specific gas emission rates are disproportionately high relative to the terrestrial landscape, both stream surface area and catchment normalized emission rates were lower than those documented for the Yukon River Basin as a whole. This may be due to limitations of C sources and/or C transport to surface waters.

Quality of surface-water runoff in selected streams in the San Antonio segment of the Edwards aquifer recharge zone, Bexar County, Texas, 1997-2012

USGS Publications Warehouse

Opsahl, Stephen P.

2012-01-01

During 1997–2012, the U.S. Geological Survey, in cooperation with the San Antonio Water System, collected and analyzed water-quality constituents in surface-water runoff from five ephemeral stream sites near San Antonio in northern Bexar County, Texas. The data were collected to assess the quality of surface water that recharges the Edwards aquifer. Samples were collected from four stream basins that had small amounts of developed land at the onset of the study but were predicted to undergo substantial development over a period of several decades. Water-quality samples also were collected from a fifth stream basin located on land protected from development to provide reference data by representing undeveloped land cover. Water-quality data included pH, specific conductance, chemical oxygen demand, dissolved solids (filtered residue on evaporation in milligrams per liter, dried at 180 degrees Celsius), suspended solids, major ions, nutrients, trace metals, and pesticides. Trace metal concentration data were compared to the Texas Commission on Environmental Quality established surface water quality standards for human health protection (water and fish). Among all constituents in all samples for which criteria were available for comparison, only one sample had one constituent which exceeded the surface water criteria on one occasion. A single lead concentration (2.76 micrograms per liter) measured in a filtered water sample exceeded the surface water criteria of 1.15 micrograms per liter. The average number of pesticide detections per sample in stream basins undergoing development ranged from 1.8 to 6.0. In contrast, the average number of pesticide detections per sample in the reference stream basin was 0.6. Among all constituents examined in this study, pesticides, dissolved orthophosphate phosphorus, and dissolved total phosphorus demonstrated the largest differences between the four stream basins undergoing development and the reference stream basin with undeveloped land cover.

Production of sea lamprey larvae from nests in two Lake Superior streams

USGS Publications Warehouse

Manion, Patrick J.

1968-01-01

The life history of the landlocked sea lamprey, Petromyzon marinus, has been described by several authors, the two most recent of which are Applegate and Wigley. The only information on the production of larvae from nests of the sea lamprey was reported by Applegate, who counted the larvae from three nests in the Ocqueoc River, a tributary of Lake Huron. The present report presents data on the hatching success of sea lamprey larvae from 19 nests in two small tributaries of southern Lake Superior and indicates greater production per nest than that recorded by Applegate. Studies were conducted by personnel of the U.S. Bureau of Commercial Fisheries on the Little Garlic River, Marquette County, Michigan, and on the Traverse River, Keweenaw County, Michigan.

Low-Frequency Surface Backscattering Strengths Measured in the Critical Sea Test Experiments

DTIC Science & Technology

2017-01-19

Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/7160--17-9702 Low-Frequency Surface Backscattering Strengths Measured in the Critical Sea ...LIMITATION OF ABSTRACT Low-Frequency Surface Backscattering Strengths Measured in the Critical Sea Test Experiments Roger C. Gauss1 and Joseph M...significantly- updated results from 55 broadband SUS SSS measurements in 6 Critical Sea Test (CST) experiments. Since the time of the previously

Experimental Sea Slicks in the Marsen (Maritime Remote Sensing) Exercise.

DTIC Science & Technology

1980-10-30

Experimental slicks with various surface properties were generated in the North Sea as part of the MARSEN (Maritime Remote Sensing ) exercise. The one...with remote sensing instrumentation. Because of the numerous effects of surface films on air-sea interfacial processes, these experiments were designed...information was obtained on the influence of sea surface films on the interpretation of signals received by remote sensing systems. Criteria for the

The vertical correction of point cloud strips performed over the coastal zone of changing sea level

NASA Astrophysics Data System (ADS)

Gasińska-Kolyszko, Ewa; Furmańczyk, Kazimierz

2017-10-01

The main principle of LIDAR is to measure the accurate time of the laser pulses sent from the system to the target surface. In the operation, laser pulses gradually scan the water surface and in combination with aircraft speed they should perform almost simultaneous soundings of each strip. Vectors sent from aircraft to the Sea are linked to the position of the aircraft. Coordinates of the points - X, Y, Z, are calculated at the time of each measurement. LIDAR crosses the surface of the sea while other impulses pass through the water column and, depending on the depth of the water, reflect from the seabed. Optical receiver on board of the aircraft detects pulse reflections from the seabed and sea surface. On the tidal water basins lidar strips must be adjusted by the changes in sea level. The operation should be reduced to a few hours during low water level. Typically, a surface of 20 to 30 km2 should be covered in an hour. The Baltic Sea is an inland sea, and the surveyed area is located in its South - western part, where meteorological and hydrological conditions affect the sea level changes in a short period of time. A lidar measurement of sea surface, that was done within 2 days, in the coastal zone of the Baltic Sea and the sea level measured 6 times a day at 8, 12, 16, 20, 00, 04 by a water gauge located in the port of Dziwnów (Poland) were used for this study. On the basis of the lidar data, strips were compared with each other. Calculation of time measurement was made for each single line separately. Profiles showing the variability of sea level for each neighboring and overlapping strips were generated. Differences were calculated changes in sea level were identified and on such basis, an adjustment was possible to perform. Microstation software and terrasolid application were used during the research. The latter allowed automatically and manual classification of the point cloud. A sea surface class was distinguished that way. Point cloud was adjusted to flight lines in terms of time and then compared.

75 FR 34666 - Stream Protection Rule; Environmental Impact Statement

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-18

... DEPARTMENT OF THE INTERIOR Office of Surface Mining Reclamation and Enforcement 30 CFR Chapter VII RIN 1029-AC63 Stream Protection Rule; Environmental Impact Statement AGENCY: Office of Surface Mining... impact statement. [[Page 34667

Reflective properties of melt ponds on sea ice

NASA Astrophysics Data System (ADS)

Malinka, Aleksey; Zege, Eleonora; Istomina, Larysa; Heygster, Georg; Spreen, Gunnar; Perovich, Donald; Polashenski, Chris

2018-06-01

Melt ponds occupy a large part of the Arctic sea ice in summer and strongly affect the radiative budget of the atmosphere-ice-ocean system. In this study, the melt pond reflectance is considered in the framework of radiative transfer theory. The melt pond is modeled as a plane-parallel layer of pure water upon a layer of sea ice (the pond bottom). We consider pond reflection as comprising Fresnel reflection by the water surface and multiple reflections between the pond surface and its bottom, which is assumed to be Lambertian. In order to give a description of how to find the pond bottom albedo, we investigate the inherent optical properties of sea ice. Using the Wentzel-Kramers-Brillouin approximation approach to light scattering by non-spherical particles (brine inclusions) and Mie solution for spherical particles (air bubbles), we conclude that the transport scattering coefficient in sea ice is a spectrally independent value. Then, within the two-stream approximation of the radiative transfer theory, we show that the under-pond ice spectral albedo is determined by two independent scalar values: the transport scattering coefficient and ice layer thickness. Given the pond depth and bottom albedo values, the bidirectional reflectance factor (BRF) and albedo of a pond can be calculated with analytical formulas. Thus, the main reflective properties of the melt pond, including their spectral dependence, are determined by only three independent parameters: pond depth z, ice layer thickness H, and transport scattering coefficient of ice σt.The effects of the incident conditions and the atmosphere state are examined. It is clearly shown that atmospheric correction is necessary even for in situ measurements. The atmospheric correction procedure has been used in the model verification. The optical model developed is verified with data from in situ measurements made during three field campaigns performed on landfast and pack ice in the Arctic. The measured pond albedo spectra were fitted with the modeled spectra by varying the pond parameters (z, H, and σt). The coincidence of the measured and fitted spectra demonstrates good performance of the model: it is able to reproduce the albedo spectrum in the visible range with RMSD that does not exceed 1.5 % for a wide variety of melt pond types observed in the Arctic.

Sampling surface and subsurface particle-size distributions in wadable gravel-and cobble-bed streams for analyses in sediment transport, hydraulics, and streambed monitoring

Treesearch

Kristin Bunte; Steven R. Abt

2001-01-01

This document provides guidance for sampling surface and subsurface sediment from wadable gravel-and cobble-bed streams. After a short introduction to streams types and classifications in gravel-bed rivers, the document explains the field and laboratory measurement of particle sizes and the statistical analysis of particle-size distributions. Analysis of particle...

Water Resources Data, Florida, Water Year 2003, Volume 1B: Northeast Florida Ground Water

USGS Publications Warehouse

George, H.G.; Nazarian, A.P.; Dickerson, S.M.

2004-01-01

Water resources data for the 2003 water year in Florida consist of continuous or daily discharge for 385 streams, periodic discharge for 13 streams, continuous or daily stage for 255 streams, periodic stage for 13 streams, peak stage and discharge for 36 streams; continuous or daily elevations for 13 lakes, periodic elevations for 46 lakes; continuous ground-water levels for 441 wells, periodic ground-water levels for 1,227 wells; quality-of-water data for 133 surface-water sites and 308 wells. The data for northeast Florida include continuous or daily discharge for 138 streams, periodic discharge for 3 streams, continuous or daily stage for 61 streams, periodic stage for 0 streams; peak stage and discharge for 0 streams; continuous or daily elevations for 9 lakes, periodic elevations for 20 lakes; continuous ground water levels for 73 wells, periodic groundwater levels for 543 wells; quality-of-water data for 43 surface-water sites and 115 wells. These data represent the National Water Data System records collected by the U.S. Geological Survey and cooperating local, State and Federal agencies in Florida.

A study of the dynamics of droughts in Northern Brazil: Observations, theory, and numerical experiments with a global atmospheric circulation model

NASA Technical Reports Server (NTRS)

Shukla, J.; Moura, A. D.

1980-01-01

The monthly mean sea surface temperature anomalies over tropical Altantic and rainfall anomalies over two selected stations for 25 years (1948-1972) were examined. It is found that the most severe drought events are associated with the simultaneous occurrence of warm sea surface temperature anomalies over north and cold sea surface temperature anomalies over south tropical Atlantic. Simultaneous occurrences of warm sea surface temperature anomaly at 15 deg N, 45 deg W and cold sea surface temperature anomaly at 15 deg S, 5 deg W were always associated with negative anomalies of rainfall, and vice versa. A simple primitive equation model is used to calculate the frictionally controlled and thermally driven circulation due to a prescribed heating function in a resting atmosphere.

The color of melt ponds on Arctic sea ice

NASA Astrophysics Data System (ADS)

Lu, Peng; Leppäranta, Matti; Cheng, Bin; Li, Zhijun; Istomina, Larysa; Heygster, Georg

2018-04-01

Pond color, which creates the visual appearance of melt ponds on Arctic sea ice in summer, is quantitatively investigated using a two-stream radiative transfer model for ponded sea ice. The upwelling irradiance from the pond surface is determined and then its spectrum is transformed into RGB (red, green, blue) color space using a colorimetric method. The dependence of pond color on various factors such as water and ice properties and incident solar radiation is investigated. The results reveal that increasing underlying ice thickness Hi enhances both the green and blue intensities of pond color, whereas the red intensity is mostly sensitive to Hi for thin ice (Hi < 1.5 m) and to pond depth Hp for thick ice (Hi > 1.5 m), similar to the behavior of melt-pond albedo. The distribution of the incident solar spectrum F0 with wavelength affects the pond color rather than its intensity. The pond color changes from dark blue to brighter blue with increasing scattering in ice, and the influence of absorption in ice on pond color is limited. The pond color reproduced by the model agrees with field observations for Arctic sea ice in summer, which supports the validity of this study. More importantly, the pond color has been confirmed to contain information about meltwater and underlying ice, and therefore it can be used as an index to retrieve Hi and Hp. Retrievals of Hi for thin ice (Hi < 1 m) agree better with field measurements than retrievals for thick ice, but those of Hp are not good. The analysis of pond color is a new potential method to obtain thin ice thickness in summer, although more validation data and improvements to the radiative transfer model will be needed in future.

The proximal part of the giant submarine Wailau landslide, Molokai, Hawaii

USGS Publications Warehouse

Clague, D.A.; Moore, J.G.

2002-01-01

The main break-in-slope on the northern submarine flank of Molokai at -1500 to -1250 m is a shoreline feature that has been only modestly modified by the Wailau landslide. Submarine canyons above the break-in-slope, including one meandering stream, were subaerially carved. Where such canyons cross the break-in-slope, plunge pools may form by erosion from bedload sediment carried down the canyons. West Molokai Volcano continued infrequent volcanic activity that formed a series of small coastal sea cliffs, now submerged, as the island subsided. Lavas exposed at the break-in-slope are subaerially erupted and emplaced tholeiitic shield lavas. Submarine rejuvenated-stage volcanic cones formed after the landslide took place and following at least 400-500 m of subsidence after the main break-in-slope had formed. The sea cliff on east Molokai is not the headwall of the landslide, nor did it form entirely by erosion. It may mark the location of a listric fault similar to the Hilina faults on present-day Kilauea Volcano. The Wailau landslide occurred about 1.5 Ma and the Kalaupapa Peninsula most likely formed 330??5 ka. Molokai is presently stable relative to sea level and has subsided no more than 30 m in the last 330 ka. At their peak, West and East Molokai stood 1.6 and 3 km above sea level. High rainfall causes high surface runoff and formation of canyons, and increases groundwater pressure that during dike intrusions may lead to flank failure. Active shield or postshield volcanism (with dikes injected along rift zones) and high rainfall appear to be two components needed to trigger the deep-seated giant Hawaiian landslides. ?? 2002 Elsevier Science B.V. All rights reserved.

OCTS and SeaWiFS Bio-Optical Algorithm and Product Validation and Intercomparison in US Coastal Waters. Chapter 5

NASA Technical Reports Server (NTRS)

Brown, Christopher W.; Subramaniam, Ajit; Culver, Mary; Brock, John C.

2001-01-01

Monitoring the health of US coastal waters is an important goal of the National Oceanic and Atmospheric Administration (NOAA). Satellite sensors are capable of providing daily synoptic data of large expanses of the US coast. Ocean color sensors, in particular, can be used to monitor the water quality of coastal waters on an operational basis. To appraise the validity of satellite-derived measurements, such as chlorophyll concentration, the bio-optical algorithms used to derive them must be evaluated in coastal environments. Towards this purpose, over 21 cruises in diverse US coastal waters have been conducted. Of these 21 cruises, 12 have been performed in conjunction with and under the auspices of the NASA/Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project. The primary goal of these cruises has been to obtain in-situ measurements of downwelling irradiance, upwelling radiance, and chlorophyll concentrations in order to evaluate bio-optical algorithms that estimate chlorophyll concentration. In this Technical Memorandum, we evaluate the ability of five bio-optical algorithms, including the current Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) algorithm, to estimate chlorophyll concentration in surface waters of the South Atlantic Bight (SAB). The SAB consists of a variety of environments including coastal and continental shelf regimes, Gulf Stream waters, and the Sargasso Sea. The biological and optical characteristics of the region is complicated by temporal and spatial variability in phytoplankton composition, primary productivity, and the concentrations of colored dissolved organic matter (CDOM) and suspended sediment. As such, the SAB is an ideal location to test the robustness of algorithms for coastal use.

Seasonal signatures in SFG vibrational spectra of the sea surface nanolayer at Boknis Eck Time Series Station (SW Baltic Sea)

NASA Astrophysics Data System (ADS)

Laß, K.; Bange, H. W.; Friedrichs, G.

2013-02-01

The very thin sea surface nanolayer on top of the sea surface microlayer, sometimes just one monomolecular layer thick, forms the interface between ocean and atmosphere. Due to the small dimension and tiny amount of substance, knowledge about the development of the layer in the course of the year is scarce. In this work, the sea surface nanolayer at Boknis Eck Time Series Station (BE), southwestern Baltic Sea, has been investigated over a period of three and a half years. Surface water samples were taken monthly by screen sampling and were analyzed in terms of organic content and composition by sum frequency generation spectroscopy, which is specifically sensitive to interfacial layers. A yearly periodicity has been observed with a pronounced abundance of sea surface nanolayer material (such as carbohydrate-rich material) during the summer months. On the basis of our results we conclude that the abundance of organic material in the nanolayer at Boknis Eck is not directly related to phytoplankton abundance. We suggest that indeed sloppy feeding of zooplankton together with photochemical and/or microbial processing of organic precursor compounds are responsible for the pronounced seasonality.

Seasonal signatures in SFG vibrational spectra of the sea surface nanolayer at Boknis Eck Time Series Station (SW Baltic Sea)

NASA Astrophysics Data System (ADS)

Laß, K.; Bange, H. W.; Friedrichs, G.

2013-08-01

The very thin sea surface nanolayer on top of the sea surface microlayer, sometimes just one monomolecular layer thick, forms the interface between ocean and atmosphere. Due to the small dimension and tiny amount of substance, knowledge about the development of the layer in the course of the year is scarce. In this work, the sea surface nanolayer at Boknis Eck Time Series Station (BE), southwestern Baltic Sea, has been investigated over a period of three and a half years. Surface water samples were taken monthly by screen sampling and were analyzed in terms of organic content and composition by sum frequency generation spectroscopy, which is specifically sensitive to interfacial layers. A yearly periodicity has been observed with a pronounced abundance of sea surface nanolayer material (such as carbohydrate-rich material) during the summer months. On the basis of our results we conclude that the abundance of organic material in the nanolayer at Boknis Eck is not directly related to phytoplankton abundance alone. We speculate that indeed sloppy feeding of zooplankton together with photochemical and/or microbial processing of organic precursor compounds is responsible for the pronounced seasonality.

Predicting the Turbulent Air-Sea Surface Fluxes, Including Spray Effects, from Weak to Strong Winds

DTIC Science & Technology

2012-09-30

almost complete decoupling of the wind field from the sea surface . As a result of the weak surface stress, the flow becomes almost free from the...shore flow . In turn, wave growth and the associated surface roughness (z0) are limited. Consequently, the stability increases further in a...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Predicting the Turbulent Air-Sea Surface Fluxes

TERMINAL ELECTRON ACCEPTING PROCESSES IN THE ALLUVIAL SEDIMENTS OF A HEADWATER STREAM

EPA Science Inventory

Chemical fluxes between catchments and streams are influenced by biochemical processes in the groundwater-stream water (GW-SW) ecotone, the interface between stream surface water and groundwater. Terminal electron accepting processes (TEAPs) that are utilized in respiration of ...

Wetlands inform how climate extremes influence surface water expansion and contraction

NASA Astrophysics Data System (ADS)

Vanderhoof, Melanie K.; Lane, Charles R.; McManus, Michael G.; Alexander, Laurie C.; Christensen, Jay R.

2018-03-01

Effective monitoring and prediction of flood and drought events requires an improved understanding of how and why surface water expansion and contraction in response to climate varies across space. This paper sought to (1) quantify how interannual patterns of surface water expansion and contraction vary spatially across the Prairie Pothole Region (PPR) and adjacent Northern Prairie (NP) in the United States, and (2) explore how landscape characteristics influence the relationship between climate inputs and surface water dynamics. Due to differences in glacial history, the PPR and NP show distinct patterns in regards to drainage development and wetland density, together providing a diversity of conditions to examine surface water dynamics. We used Landsat imagery to characterize variability in surface water extent across 11 Landsat path/rows representing the PPR and NP (images spanned 1985-2015). The PPR not only experienced a 2.6-fold greater surface water extent under median conditions relative to the NP, but also showed a 3.4-fold greater change in surface water extent between drought and deluge conditions. The relationship between surface water extent and accumulated water availability (precipitation minus potential evapotranspiration) was quantified per watershed and statistically related to variables representing hydrology-related landscape characteristics (e.g., infiltration capacity, surface storage capacity, stream density). To investigate the influence stream connectivity has on the rate at which surface water leaves a given location, we modeled stream-connected and stream-disconnected surface water separately. Stream-connected surface water showed a greater expansion with wetter climatic conditions in landscapes with greater total wetland area, but lower total wetland density. Disconnected surface water showed a greater expansion with wetter climatic conditions in landscapes with higher wetland density, lower infiltration and less anthropogenic drainage. From these findings, we can expect that shifts in precipitation and evaporative demand will have uneven effects on surface water quantity. Accurate predictions regarding the effect of climate change on surface water quantity will require consideration of hydrology-related landscape characteristics including wetland storage and arrangement.