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Articles 151 - 180 of 196
Full-Text Articles in Physical Sciences and Mathematics
Cretaceous-Paleogene Dinoflagellate Biostratigraphy And The Age Of The Clayton Formation, Southeastern Missouri, Usa, Natalie R. Dastas, John A. Chamberlain Jr., Matthew P. Garb
Cretaceous-Paleogene Dinoflagellate Biostratigraphy And The Age Of The Clayton Formation, Southeastern Missouri, Usa, Natalie R. Dastas, John A. Chamberlain Jr., Matthew P. Garb
Publications and Research
Sedimentary deposits in Stoddard County, southeastern Missouri, reveal a K-Pg transition sequence represented by the uppermost Maastrichtian Owl Creek Formation and the Paleocene Clayton Formation. The Clayton Formation is characterized by a basal fossiliferous coquinite that contains reworked late Maastrichtian macrofossils. Dinoflagellate biostratigraphy is used to determine the age of the coquinite layer and specifically whether or not it is an end-K tsunamite deposit resulting from the Chicxulub impact event. Results indicate a mixed assemblage of late Maastrichtian and early Danian dinocysts within the basal coquinite of the Clayton Formation. Maastrichtian dinocyst taxa identified are Riculacysta amplexa, Pierceites pentagonus, Phelodinium …
Groundwater Flow Across Spatial Scales: Importance For Climate Modeling, Nir Krakauer, Haibin Li, Ying Fan
Groundwater Flow Across Spatial Scales: Importance For Climate Modeling, Nir Krakauer, Haibin Li, Ying Fan
Publications and Research
Current regional and global climate models generally do not represent groundwater flow between grid cells as a component of the water budget. We estimate the magnitude of between cell groundwater flow as a function of grid cell size by aggregating results from a numerical model of equilibrium groundwater flow run and validated globally. We find that over a broad range of cell sizes spanning that of state of the art regional and global climate models, mean between cell groundwater flow magnitudes scale with the reciprocal of grid cell length. We also derive this scaling a priori from a simple statistical …
Are Climate Model Simulations Useful For Forecasting Precipitation Trends? Hindcast And Synthetic-Data Experiments, Nir Y. Krakauer, Balázs M. Fekete
Are Climate Model Simulations Useful For Forecasting Precipitation Trends? Hindcast And Synthetic-Data Experiments, Nir Y. Krakauer, Balázs M. Fekete
Publications and Research
Water scientists and managers currently face the question of whether trends in climate variables that affect water supplies and hazards can be anticipated. We investigate to what extent climate model simulations may provide accurate forecasts of future hydrologic nonstationarity in the form of changes in precipitation amount. We compare gridded station observations (GPCC Full Data Product, 1901–2010) and climate model outputs (CMIP5 Historical and RCP8.5 simulations, 1901–2100) in real and syntheticdata hindcast experiments. The hindcast experiments show that imputing precipitation trends based on the climate model mean reduced the root mean square error of precipitation trend estimates for 1961–2010 by …
A Review Of Air–Ice Chemical And Physical Interactions (Aici): Liquids, Quasi-Liquids, And Solids In Snow, T. Bartels-Rausch, H-W Jacobi, T. F. Kahan, J. L. Thomas, E. S. Thomson, J. P. D. Abbatt, M. Ammann, J. R. Blackford, H. Bluhm, Chris Boxe, F. Domine, M. M. Frey, I. Gladich, M. I. Guzmán, D. Heger, Th. Huthwelker, P. Klán, W. F. Kuhs, M. H. Kuo, S. Maus, S. G. Moussa, V. F. Mcneill, J. T. Newberg, J. B. C. Pettersson, M. Roeselová, J. R. Sodeau
A Review Of Air–Ice Chemical And Physical Interactions (Aici): Liquids, Quasi-Liquids, And Solids In Snow, T. Bartels-Rausch, H-W Jacobi, T. F. Kahan, J. L. Thomas, E. S. Thomson, J. P. D. Abbatt, M. Ammann, J. R. Blackford, H. Bluhm, Chris Boxe, F. Domine, M. M. Frey, I. Gladich, M. I. Guzmán, D. Heger, Th. Huthwelker, P. Klán, W. F. Kuhs, M. H. Kuo, S. Maus, S. G. Moussa, V. F. Mcneill, J. T. Newberg, J. B. C. Pettersson, M. Roeselová, J. R. Sodeau
Publications and Research
Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air–ice interface, often termed quasi-liquid …
Brownfield Action: Dissemination Of A Sencer Model Curriculum And The Creation Of A Collaborative Stem Education Network, Peter Bower, Ryan Kelsey, Joseph Liddicoat, Doug M. Thompson, Angelo Lampousis, Bret Bennington, Bess Greenbaum Seewald, Arthur D. Kney, Saugata Datta, Lawrence D. Lemke, Briane Sorice Miccio, Tamara Graham
Brownfield Action: Dissemination Of A Sencer Model Curriculum And The Creation Of A Collaborative Stem Education Network, Peter Bower, Ryan Kelsey, Joseph Liddicoat, Doug M. Thompson, Angelo Lampousis, Bret Bennington, Bess Greenbaum Seewald, Arthur D. Kney, Saugata Datta, Lawrence D. Lemke, Briane Sorice Miccio, Tamara Graham
Publications and Research
Brownfield Action (BA) is a web-based environmental site assessment (ESA) simulation in which students form geotechnical consulting companies and work together to solve problems in environmental forensics. Developed at Barnard College with the Columbia Center for New Media Teaching and Learning, BA has been disseminated to ten colleges, universities, and high schools, resulting in a collaborative network of educators. The experiences of current users are presented describing how they have incorporated the BA curriculum into their courses, as well as how BA affected teaching and learning. The experiences demonstrate that BA can be used in whole or in part, is …
Biome Q10 And Dryness, Chuixiang Yi, Daniel Ricciuto, George Hendrey
Biome Q10 And Dryness, Chuixiang Yi, Daniel Ricciuto, George Hendrey
Publications and Research
Temperature sensitivity of soil respiration (Q10) is a critical parameter in carbon cycle models with important implications for climate-carbon feedbacks in the 21st century. The common assumption of a constant Q10, usually with a value of 2.0, was shown to be invalid by a previous model-data fusion study that reported biome-specific values of this parameter. We extend the previous analysis by demonstrating that these biome-level values of Q10 also are a function of dryness (R2 = 0.54). When tundra and cultivated lands are excluded, the correlation is much stronger (R2 = 0.92). Therefore …
Assessing The Performance Of A Northern Gulf Of Mexico Tidal Model Using Satellite Imagery, Stephen C. Medeiros, Scott C. Hagen, Naira Chaouch, Jesse Feyen, Marouane Temimi, John F. Weishampel, Yuji Funakoshi, Reza Khanbilvardi
Assessing The Performance Of A Northern Gulf Of Mexico Tidal Model Using Satellite Imagery, Stephen C. Medeiros, Scott C. Hagen, Naira Chaouch, Jesse Feyen, Marouane Temimi, John F. Weishampel, Yuji Funakoshi, Reza Khanbilvardi
Publications and Research
Tidal harmonic analysis simulations along with simulations spanning four specific historical time periods in 2003 and 2004 were conducted to test the performance of a northern Gulf of Mexico tidal model. A recently developed method for detecting inundated areas based on integrated remotely sensed data (i.e., Radarsat-1, aerial imagery, LiDAR, Landsat 7 ETM+) was applied to assess the performance of the tidal model. The analysis demonstrates the applicability of the method and its agreement with traditional performance assessment techniques such as harmonic resynthesis and water level time series analysis. Based on the flooded/non-flooded coastal areas estimated by the integrated remotely …
An Apparent Angular Unconformity In Western Connecticut, Stanley Schleifer, Nazrul I. Khandaker, Adisa Charles, Hernando Martinez, Shirley Jackson, Chiemeka Ihebom
An Apparent Angular Unconformity In Western Connecticut, Stanley Schleifer, Nazrul I. Khandaker, Adisa Charles, Hernando Martinez, Shirley Jackson, Chiemeka Ihebom
Publications and Research
The recent extension, to the north, of the U. S. Route 7 ‘superhighway’ in the town of Brookfield, Connecticut has involved the excavation of crystalline bedrock of lower Paleozoic to upper Proterozoic age in the area. The road cuts produced by this excavation have exposed some interesting features of structure and lithology. An outcrop, observed by the authors off the east side of route 7, at grid coordinates 41.482444 N, 73.415307 W is of particular interest. It appears, to the casual observer to be an angular unconformity. Maps and publications regarding this area of Western Connecticut support the likelihood of …
Tectonosedimentologic Significance Of The Upper Cretaceous Foreland Basin Siliciclastics: Western Interior, Usa, Nazrul I. Khandaker
Tectonosedimentologic Significance Of The Upper Cretaceous Foreland Basin Siliciclastics: Western Interior, Usa, Nazrul I. Khandaker
Publications and Research
The Upper Cretaceous Frontier Formation exposed along the western margin of the western interior foreland basin is composed of clastic sediments that were deposited during the initial late Cretaceous transgressive-regressive phases of the Western Interior Seaway across Wyoming (Figure 1). Current study is aimed at providing attendees with the best practices associated with tectonic, lithofacies and sedimentologic interpretation of foreland basin sequences and emphasizing the need for utilizing field, structural, geochemical, and compositional data for reconstructing a viable scenario connected with foreland basin sedimentary packages. An attempt will be made to compare documented sedimentological findings with foreland basins located in …
Impacts Of Soil-Acquifer Heat And Water Fluxes On Simulated Global Climate, Nir Krakauer, M. J. Puma, B. I. Cook
Impacts Of Soil-Acquifer Heat And Water Fluxes On Simulated Global Climate, Nir Krakauer, M. J. Puma, B. I. Cook
Publications and Research
Climate models have traditionally only represented heat and water fluxes within relatively shallow soil layers, but there is increasing interest in the possible role of heat and water exchanges with the deeper subsurface. Here, we integrate an idealized 50m deep aquifer into the land surface module of the GISS ModelE general circulation model to test the influence of aquifer-soil moisture and heat exchanges on climate variables. We evaluate the impact on the modeled climate of aquifer-soil heat and water fluxes separately, as well as in combination. The addition of the aquifer to ModelE has limited impact on annual-mean climate, with …
Allometric Scaling And Resource Limitations Model Of Tree Heights: Part 1. Model Optimization And Testing Over Continental Usa, Yuli Shi, Sungho Choi, Xiliang Ni, Sangram Ganguly, Gong Zhang, Hieu V. Duong, Michael A. Lefsky, Marc Simard, Sassan S. Saatchi, Shihyan Lee, Wenge Ni-Meister, Shilong Piao, Chunxiang Cao, Ramakrishna R. Nemani, Ranga B. Myneni
Allometric Scaling And Resource Limitations Model Of Tree Heights: Part 1. Model Optimization And Testing Over Continental Usa, Yuli Shi, Sungho Choi, Xiliang Ni, Sangram Ganguly, Gong Zhang, Hieu V. Duong, Michael A. Lefsky, Marc Simard, Sassan S. Saatchi, Shihyan Lee, Wenge Ni-Meister, Shilong Piao, Chunxiang Cao, Ramakrishna R. Nemani, Ranga B. Myneni
Publications and Research
A methodology to generate spatially continuous fields of tree heights with an optimized Allometric Scaling and Resource Limitations (ASRL) model is reported in this first of a multi-part series of articles. Model optimization is performed with the Geoscience Laser Altimeter System (GLAS) waveform data. This methodology is demonstrated by mapping tree heights over forested lands in the continental USA (CONUS) at 1 km spatial resolution. The study area is divided into 841 eco-climatic zones based on three forest types, annual total precipitation classes (30 mm intervals) and annual average temperature classes (2 °C intervals). Three model parameters (area of single …
Assessing Continuous Contamination Discharge From A Combined Sewer Outfall (Cso) Into A Tidal Wetland Creek: Bacteriological And Heavy Metals Indicators, Timothy Eaton, Gregory D. O'Mullan, Ashaki A. Rouff
Assessing Continuous Contamination Discharge From A Combined Sewer Outfall (Cso) Into A Tidal Wetland Creek: Bacteriological And Heavy Metals Indicators, Timothy Eaton, Gregory D. O'Mullan, Ashaki A. Rouff
Publications and Research
Continuous discharge from a combined sewer overflow (CSO) into a tidal wetland creek in the New York City urban area was analyzed to assess the extent of water quality degradation from fecal bacteria contamination during both dry and wet weather. A combination of fecal indicator bacteria (FIB), total suspended solids, and dissolved metals were used to infer the presence of sewage pollution from the CSO discharge and to constrain the spatial and temporal impact on water quality and dry season creek flows. Upstream of the CSO, creek flow was dominated by groundwater input, and FIB levels were very low or …
Stratigraphic Constraints On Groundwater Flow: Examples From York College, Cuny Campus In Queens, New York City, Nazrul I. Khandaker, Stanley Schleifer, Ezazul Haque, Coreyn Goddard, Shirley Jackson
Stratigraphic Constraints On Groundwater Flow: Examples From York College, Cuny Campus In Queens, New York City, Nazrul I. Khandaker, Stanley Schleifer, Ezazul Haque, Coreyn Goddard, Shirley Jackson
Publications and Research
Surficial geology of the York College campus is dominated by recent glacial deposits dating back to late Wisconsinan event. Several shallow excavation-type trenches reaching a depth of approximately 6 to 10 feet were dug in the wide greeneries adjacent to the parking lot to determine soil texture and collect in-situ permeability data. Based on these shallow pits, an apparent subsurface stratigraphy has been constructed. In general, the uppermost 8 to 18 inches is mostly clayey-and-silty sand and organic-rich top soil overlying stratified drift. The uppermost horizons are observed to also contain fill materials such as bricks, concretes, broken glasses, and …
Information Content Of Seasonal Forecasts In A Changing Climate, Nir Krakauer, Michael D. Grossberg, Irina Gladkova, Hannah Aizenman
Information Content Of Seasonal Forecasts In A Changing Climate, Nir Krakauer, Michael D. Grossberg, Irina Gladkova, Hannah Aizenman
Publications and Research
We study the potential value to stakeholders of probabilistic long-term forecasts, as quantified by the mean information gain of the forecast compared to climatology. We use as a case study the USA Climate Prediction Center (CPC) forecasts of 3-month temperature and precipitation anomalies made at 0.5-month lead time since 1995. Mean information gain was positive but low (about 2% and 0.5% of the maximum possible for temperature and precipitation forecasts, resp.) and has not increased over time. Information-based skill scores showed similar patterns to other, non-information-based, skill scores commonly used for evaluating seasonal forecasts but tended to be smaller, suggesting …
Development Of A Ground Based Remote Sensing Approach For Direct Evaluation Of Aerosol-Cloud Interaction, Bomidi Lakshmi Madhavan, Yuzhe He, Yonghua Wu, Barry Gross, Fred Moshary, Samir Ahmed
Development Of A Ground Based Remote Sensing Approach For Direct Evaluation Of Aerosol-Cloud Interaction, Bomidi Lakshmi Madhavan, Yuzhe He, Yonghua Wu, Barry Gross, Fred Moshary, Samir Ahmed
Publications and Research
The possible interaction and modification of cloud properties due to aerosols is one of the most poorly understood mechanisms within climate studies, resulting in the most significant uncertainty as regards radiation budgeting. In this study, we explore direct ground based remote sensing methods to assess the Aerosol-Cloud Indirect Effect directly, as space-borne retrievals are not directly suitable for simultaneous aerosol/cloud retrievals. To illustrate some of these difficulties, a statistical assessment of existing multispectral imagers on geostationary (e.g., GOES)/Moderate Resolution Imaging Spectroradiometer (MODIS) satellite retrievals of the Cloud Droplet Effective Radius (Reff) showed significant biases especially at larger solar zenith angles, …
Tectonics And Sedimentary Facies Interpretation Of The Mesozoic Giron Group, Colombia, Hernando Martinez-Sacristan, Ricardo Mier-Umana, Nazrul I. Khandaker, Stanley Schleifer, Diana Lucia Leon-Martinez
Tectonics And Sedimentary Facies Interpretation Of The Mesozoic Giron Group, Colombia, Hernando Martinez-Sacristan, Ricardo Mier-Umana, Nazrul I. Khandaker, Stanley Schleifer, Diana Lucia Leon-Martinez
Publications and Research
Preliminary field investigations involving exposed Giron Group sediments in Colombia provided some interesting geologic information in terms of provenance, depositional environments, and development of the Mesozoic synrift sedimentary basins in Colombia. Overall, the synrift Triassic-Jurassic rift-related volcanic rocks, redbeds, and evaporites are prominent in Colombia, and a thick basin sequence of Cretaceous sandstones and shales dominates the central part of the Cordillera Oriental. These were mostly deposited in dominantly north-trending grabens. Identified sedimentary rock types were arkose, clast-and-matrix-supported conglomerate, red mudstone, variegated sandstone, siltstone and breccia. Extensive kaolinitization was noticeable in several sandstone samples. Among the notable sedimentary structures were …
Potential Significance Of Photoexcited No2 On Global Air Quality With The Nmmb/Bsc Chemical Transport Model, O. Jorba, D. Dabdub, Christopher S. Blaszczak-Boxe, C. Pérez, Z. Janjic, J. M. Baldasano, M. Spada, A. Badia, M. Gonçalves
Potential Significance Of Photoexcited No2 On Global Air Quality With The Nmmb/Bsc Chemical Transport Model, O. Jorba, D. Dabdub, Christopher S. Blaszczak-Boxe, C. Pérez, Z. Janjic, J. M. Baldasano, M. Spada, A. Badia, M. Gonçalves
Publications and Research
Atmospheric chemists have recently focused on the relevance of the NO2* + H2O → OH + HONO reaction to local air quality. This chemistry has been considered not relevant for the troposphere from known reaction rates until nowadays. New experiments suggested a rate constant of 1.7 × 10−13 cm3 molecule−1 s−1, which is an order of magnitude faster than the previously estimated upper limit of 1.2 × 10−14 cm3 molecule−1 s−1, determined by Crowley and Carl (1997). Using the new global model, NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM), simulations are presented that assess the potential significance of this chemistry on global …
Coupling Of Fog And Marine Microbial Content In The Near-Shore Coastal Environment, M. E. Ducker, Gregory D. O'Mullan, K. C. Weathers, A. R. Juhl, M. Uriarte
Coupling Of Fog And Marine Microbial Content In The Near-Shore Coastal Environment, M. E. Ducker, Gregory D. O'Mullan, K. C. Weathers, A. R. Juhl, M. Uriarte
Publications and Research
Microbes in the atmosphere (microbial aerosols) play an important role in climate and provide an ecological and biogeochemical connection between oceanic, atmospheric, and terrestrial environments. However, the sources and environmental factors controlling the concentration, diversity, transport, and viability of microbial aerosols are poorly understood. This study examined culturable microbial aerosols from a coastal environment in Maine (USA) and determined the effect of onshore wind speed and fog presence on deposition rate, source, and community composition. During fog events with low onshore winds (
The Effect Of Dissolved Humic Acids On Aluminosilicate Formation And Associated Carbon Sequestration, Ashaki A. Rouff, Brian L. Phillips, Stacey G. Cochiara, Kathryn L. Nagy
The Effect Of Dissolved Humic Acids On Aluminosilicate Formation And Associated Carbon Sequestration, Ashaki A. Rouff, Brian L. Phillips, Stacey G. Cochiara, Kathryn L. Nagy
Publications and Research
Allophane and imogolite neogenesis in soils may occur in the presence of organic matter. To understand this process under conditions relevant to soils, the influence of dissolved organic carbon (DOC) as humic acid (HA), on aluminosilicate formation was studied at 25◦C, pH 6, and low-DOC concentrations. For solutions with initial Al/Si ratios of 1–2.1, and 0–6mg/L DOC, precipitates recovered after 20h had Al/Si ratios of 2.2–2.7. The formation of allophane, imogolite-like material, and aluminosilicate gel was confirmed by XRD, FTIR, and NMR. The effect of DOC was to produce a small, but systematic increase in imogolite-like Si in the precipitate, …
Dissemination Of Geological Information In Avoiding Geotechnical Risks Associated With Tunnel Construction: Lessons Learned From Deep Voids In Marble In Lower Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Leah Scott
Dissemination Of Geological Information In Avoiding Geotechnical Risks Associated With Tunnel Construction: Lessons Learned From Deep Voids In Marble In Lower Manhattan, New York City, Nazrul I. Khandaker, Stanley Schleifer, Masud Ahmed, Leah Scott
Publications and Research
Test boring associated with the recently accomplished City Water Tunnel # 3 in Manhattan, New York City revealed moderately to highly weathered marble with insoluble silicate residues composed mostly of phlogopite, chlorite, and tremolite. Apparent control on the weatherability of the marble was in response to original mineral constituents dominating this lithology. Encountered marble samples ranged between pure calcitic to mixed dolomitic/siliceous types. Fresh marble samples collected from adjacent boring locations revealed characteristic geochemical data: Lime (25-45%), Silica (4-7%), Alumina (1-3%), MgO (5-20%), and LOI (35-42%); compressive strength of unweathered marble varied between 2000-3000 Kg/cm2. Relict foliations with …
Stream Recession Curves And Storage Variability In Small Watersheds, Nir Y. Krakauer, Marouane Temimi
Stream Recession Curves And Storage Variability In Small Watersheds, Nir Y. Krakauer, Marouane Temimi
Publications and Research
The pattern of streamflow recession after rain events offers clues about the relationship between watershed runoff (observable as river discharge) and water storage (not directly observable) and can help in water resource assessment and prediction. However, there have been few systematic assessments of how streamflow recession varies across flow rates and how it relates to independent assessments of terrestrial water storage. We characterized the streamflow recession pattern in 61 relatively undisturbed small watersheds (1–100 km2 ) across the coterminous United States with multiyear records of hourly streamflow from automated gauges. We used the North American Regional Reanalysis to help identify …
Historical Legacies, Information And Contemporary Water Science And Management, Daniel J. Bain, Jennifer A. S. Arrigo, Mark B. Green, Brian A. Pellerin, Charles J. Vörösmarty
Historical Legacies, Information And Contemporary Water Science And Management, Daniel J. Bain, Jennifer A. S. Arrigo, Mark B. Green, Brian A. Pellerin, Charles J. Vörösmarty
Advanced Science Research Center
Hydrologic science has largely built its understanding of the hydrologic cycle using contemporary data sources (i.e., last 100 years). However, as we try to meet water demand over the next 100 years at scales from local to global, we need to expand our scope and embrace other data that address human activities and the alteration of hydrologic systems. For example, the accumulation of human impacts on water systems requires exploration of incompletely documented eras. When examining these historical periods, basic questions relevant to modern systems arise: (1) How is better information incorporated into water management strategies? (2) Does any point …
Melting Trends Over The Greenland Ice Sheet (1958-2009) From Spaceborne Microwave Data And Regional Climate Models, X. Fettweis, Marco Tedesco, M. Van Den Broeke, J. Ettema
Melting Trends Over The Greenland Ice Sheet (1958-2009) From Spaceborne Microwave Data And Regional Climate Models, X. Fettweis, Marco Tedesco, M. Van Den Broeke, J. Ettema
Publications and Research
To study near-surface melt changes over the Greenland ice sheet (GrIS) since 1979, melt extent estimates from two regional climate models were compared with those obtained from spaceborne microwave brightness temperatures using two different remote sensing algorithms. The results from the two models were consistent with those obtained with the remote sensing algorithms at both daily and yearly time scales, encouraging the use of the models for analyzing melting trends before the satellite era (1958–1979), when forcing data is available. Differences between satellite-derived and model-simulated results still occur and are used here to identify (i) biases in the snow models …
Memorial To Charles Alexander Baskerville (1928–2009), Allen W. Hatheway, Ajitkumar Shah, Joseph J. Lifrieri, Nazrul I. Khandaker, Stanley Schleifer
Memorial To Charles Alexander Baskerville (1928–2009), Allen W. Hatheway, Ajitkumar Shah, Joseph J. Lifrieri, Nazrul I. Khandaker, Stanley Schleifer
Publications and Research
Charles Alexander Baskerville captured our imagination, as a senior colleague in the practice of engineering geology in New York City. “Charlie” held the seat of master Big Apple Geologist during his matured career. He was the source, he knew the possibilities, he was aware of the pitfalls of this most geologically complex of American cities. His final work was his greatest reach—the four bedrock geologic quadrangles of the city. Baskerville mapped New York City for more than fifty years. He was sought and given access to sites of bedrock and bedrock/ overburden interface on the various capitol construction projects undertaken …
Upper Cretaceous Peay Bentonites (North-Central Wyoming): Provenance And Tectonics Interpretation From Ash Composition, Nazrul I. Khandaker, Carl F. Vondra, Karl E. Seifert, Malek Shami, Rochelle Cardinale, Thakur Chaturgan
Upper Cretaceous Peay Bentonites (North-Central Wyoming): Provenance And Tectonics Interpretation From Ash Composition, Nazrul I. Khandaker, Carl F. Vondra, Karl E. Seifert, Malek Shami, Rochelle Cardinale, Thakur Chaturgan
Publications and Research
The Peay bentonites belong to the basal Frontier Formation (Bighorn Basin, north-central Wyoming), primarily outcrop in the Bighorn Basin, rest on an extensively bioturbated sandstone unit, the Peay Sandstone, and are generally the thinner bentonitic unit. Beds of very light gray to greenish gray bentonite are also abundant in the lower Frontier units between Kaycee and Mayoworth (Powder River Basin) and are very rarely as much as 3 m thick. Bentonite occurs within the interstratified shale, sandstone, and siltstone sequences of the lower Frontier unit throughout much of the southwestern Powder River Basin. The purpose of this study is to …
Sensitivity Analysis Of B-Factor In Microwave Emission Model For Soil Moisture Retrieval: A Case Study For Smap Mission, Dugwon Seo, Tarendra Lakhankar, Reza Khanbilvardi
Sensitivity Analysis Of B-Factor In Microwave Emission Model For Soil Moisture Retrieval: A Case Study For Smap Mission, Dugwon Seo, Tarendra Lakhankar, Reza Khanbilvardi
Publications and Research
Sensitivity analysis is critically needed to better understand the microwave emission model for soil moisture retrieval using passive microwave remote sensing data. The vegetation b-factor along with vegetation water content and surface characteristics has significant impact in model prediction. This study evaluates the sensitivity of the b-factor, which is function of vegetation type. The analysis is carried out using Passive and Active L and S-band airborne sensor (PALS) and measured field soil moisture from Southern Great Plains experiment (SGP99). The results show that the relative sensitivity of the b-factor is 86% in wet soil condition and 88% in high vegetated …
Contribution Of Soil Moisture Feedback To Hydroclimatic Variability, Nir Krakauer, B. I. Cook, M. J. Puma
Contribution Of Soil Moisture Feedback To Hydroclimatic Variability, Nir Krakauer, B. I. Cook, M. J. Puma
Publications and Research
While a variety of model experiments and analyses of observations have explored the impact of soil moisture variation on climate, it is not yet clear how large or detectable soil moisture feedback is across spatial and temporal scales. Here, we study the impact of dynamic versus climatological soil moisture in the GISS GCM ModelE (with prescribed sea-surface temperatures) on the variance and on the spatial and temporal correlation scale of hydrologically relevant climate variables (evaporation, precipitation, temperature, cloud cover) over the land surface. We also confirm that synoptic variations in soil moisture have a substantial impact on the mean climate …
An Update On Groundwater Conditions At The Site Of The York College Cuny Campus In Southeastern Queens County, New York City, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Edward A. Molteni
An Update On Groundwater Conditions At The Site Of The York College Cuny Campus In Southeastern Queens County, New York City, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Edward A. Molteni
Publications and Research
The wells operated by the Jamaica Water Supply Company in Queens represent the only large scale utilization of groundwater for public water supply in New York City in recent years. These wells were shut down, for the most part, beginning in 1996. Since that time, water table elevations in the area, which had been drawn down by the withdrawal activity of the Jamaica Water Supply Company, have risen significantly causing some high groundwater problems, including flooding of basements. The New York City Department of Environmental Protection (NYCDEP) has held public hearings on a contemplated resumption of ground water withdrawal in …
The Impact Of Receiver Aperture Design And Telescope Properties On Lidar Signal-To-Noise Ratio Improvements, Yasser Hassebo, Khaled El Sayed
The Impact Of Receiver Aperture Design And Telescope Properties On Lidar Signal-To-Noise Ratio Improvements, Yasser Hassebo, Khaled El Sayed
Publications and Research
Range and sensitivities of lidar measurements in daylight are limited by sky background noise power (BGP). This is particularly important for Raman lidar techniques where the Raman backscattered signal is relatively weak. This often restricts Raman lidar measurements to nighttime where BGP is absent. The background noise elimination is particularly important in daytime measurements in case where full overlap between laser beam and receiver telescope field-of-view (FOV) is necessary. Results of numerical simulations for a vertically pointing Lidar show that significant improvements in Lidar signal to noise ratio (SNR) can be obtained, by minimizing the detected sky BGP. This can …
Provenance Of A Garnet-Rich Beach Placer Deposit, Montauk Point, Long Island, Ny, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Olalekan Jemilugba
Provenance Of A Garnet-Rich Beach Placer Deposit, Montauk Point, Long Island, Ny, Nazrul I. Khandaker, Stanley Schleifer, Zarine Ali, Olalekan Jemilugba
Publications and Research
Garnet and magnetite rich sand, also enriched in monazite and zircon, has been observed and sampled near Montauk Point, Long Island. The sediment is derived from the glacial till and stratified drift of the Ronkonkoma Moraine by mechanical weathering and erosion due to wave action at Montauk Point, the headland on the eastern tip of Long Island. Sand sized sediment is moved westward along the southern shore of Long Island by longshore transport. The garnet and magnetite components of this sediment are significantly denser than the quartzo-feldspathic components. This allows for hydraulic segregation of these components, by wave action, …