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Articles 1 - 14 of 14
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Linear Trend Detection In Serially Dependent Hydrometeorological Data Based On A Variance Correction Spearman Rho Method, Wenpeng Weng, Yuanfang Chen, Stefan Becker, Bo Liu
Linear Trend Detection In Serially Dependent Hydrometeorological Data Based On A Variance Correction Spearman Rho Method, Wenpeng Weng, Yuanfang Chen, Stefan Becker, Bo Liu
Publications and Research
Hydrometeorological data are commonly serially dependent and thereby deviate from the assumption of independence that underlies the Spearman rho trend test. The presence of autocorrelation will influence the significance of observed trends. Specifically, the positive autocorrelation inflates Type І errors, while it deflates the power of trend detection in some cases. To address this issue, we derive a theoretical formula and recommend an appropriate empirical formula to calculate the rho variance of dependent series. The proposed procedure of the variance correction for the Spearman rho method is capable of mitigating the effect of autocorrelation on both, Type І error and …
Development And Evaluation Of A Multi-Year Fractional Surface Water Data Set Derived From Active/Passive Microwave Remote Sensing Data, Ronny Schroeder, Kyle C. Mcdonald, Bruce D. Chapman, Katherine Jensen, Erika Podest, Zachary D. Tessler, Theodore J. Bohn, Reiner Zimmermann
Development And Evaluation Of A Multi-Year Fractional Surface Water Data Set Derived From Active/Passive Microwave Remote Sensing Data, Ronny Schroeder, Kyle C. Mcdonald, Bruce D. Chapman, Katherine Jensen, Erika Podest, Zachary D. Tessler, Theodore J. Bohn, Reiner Zimmermann
Publications and Research
The sensitivity of Earth’s wetlands to observed shifts in global precipitation and temperature patterns and their ability to produce large quantities of methane gas are key global change questions. We present a microwave satellite-based approach for mapping fractional surface water (FW) globally at 25-km resolution. The approach employs a land cover-supported, atmospherically-corrected dynamic mixture model applied to 20+ years (1992–2013) of combined, daily, passive/active microwave remote sensing data. The resulting product, known as Surface WAter Microwave Product Series (SWAMPS), shows strong microwave sensitivity to sub-grid scale open water and inundated wetlands comprising open plant canopies. SWAMPS’ FW compares favorably (R2 …
A College Level Geology Field Trip In Western Connecticut And Vicinity, Stanley Schleifer, Nazrul I. Khandaker, Keshaw Narine, Ezazul Haque, Ratan Dhar
A College Level Geology Field Trip In Western Connecticut And Vicinity, Stanley Schleifer, Nazrul I. Khandaker, Keshaw Narine, Ezazul Haque, Ratan Dhar
Publications and Research
There are a number of excellent locations for field exposure for college students in, and around Western Connecticut. These are accessible for a one day field trip within striking distance of New York City, Bridgeport and New Haven, CT and other nearby locations. They are also suitable for an expanded weekend field trip. The field locations include; Kent Falls State Park, Kent, CT, Dinosaur State Park, Rocky Hill, CT, the Hubbard Mining Museum, Kent, CT, Bash Bish Falls in Mt. Washington, Massachusetts, Macedonia Brook State Park in Kent, CT and various outcrops exposed along U. S. Route 7 north of …
Comparative Sorption Of Methylene Blue Onto Hydrophobic Clays, Alvaro D. Sponza, Natalia J. Fernandez, David Yang, Karla A. Ortiz, Abel E. Navarro
Comparative Sorption Of Methylene Blue Onto Hydrophobic Clays, Alvaro D. Sponza, Natalia J. Fernandez, David Yang, Karla A. Ortiz, Abel E. Navarro
Publications and Research
Chemical modifications of clay to remove methylene blue (MB) from aqueous solutions at room temperature were compared. Natural bentonite (NC) was modified by cation exchange with hexadecyltrimethylammonium chloride (HC), bencyltriethylammonium chloride (BC), and tetramethylammonium chloride (TC) to reverse the surface polarity of the hydrophilic bentonite. The adsorption of MB was studied and fitted by the adsorption theories of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin. Equilibrium parameters were calculated, indicating that chemical modification did not improve the adsorption, due to the electrostatic adsorption mechanism. Specific surface area was determined, reporting the following trend: NC > TC > BC > HC. Isotherms show that TC is …
Estimates Of Micro-, Nano-, And Picoplankton Contributions To Particle Export In The Northeast Pacific, B. L. Mackinson, S. B. Moran, M. W. Lomas, Gillian M. Stewart, R. P. Kelly
Estimates Of Micro-, Nano-, And Picoplankton Contributions To Particle Export In The Northeast Pacific, B. L. Mackinson, S. B. Moran, M. W. Lomas, Gillian M. Stewart, R. P. Kelly
Publications and Research
The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th;238U disequilibria and, during two cruises, measured by a sediment trap at Ocean Station Papa. POC fluxes at 100m ranged from 0.65 to 7.95 mmolm2 d1, similar in magnitude to previous results at Line P. Microplankton pigments dominate indicator pigment fluxes (averaging 6919% of total pigment …
Evaluation Of Alos Palsar Data For High-Resolution Mapping Of Vegetated Wetlands In Alaska, Daniel Clewley, Jane Whitcomb, Mahta Moghaddam, Kyle Macdonald, Bruce Chapman, Peter Bunting
Evaluation Of Alos Palsar Data For High-Resolution Mapping Of Vegetated Wetlands In Alaska, Daniel Clewley, Jane Whitcomb, Mahta Moghaddam, Kyle Macdonald, Bruce Chapman, Peter Bunting
Publications and Research
As the largest natural source of methane, wetlands play an important role in the carbon cycle. High-resolution maps of wetland type and extent are required to quantify wetland responses to climate change. Mapping northern wetlands is particularly important because of a disproportionate increase in temperatures at higher latitudes. Synthetic aperture radar data from a spaceborne platform can be used to map wetland types and dynamics over large areas. Following from earlier work by Whitcomb et al. (2009) using Japanese Earth Resources Satellite (JERS-1) data, we applied the “random forests” classification algorithm to variables from L-band ALOS PALSAR data for 2007, …
Mapping Regional Inundation With Spaceborne L-Band Sar, Bruce Chapman, Kyle Macdonald, Masanobu Shimada, Ake Rosenqvist, Ronny Schroeder, Laura Hess
Mapping Regional Inundation With Spaceborne L-Band Sar, Bruce Chapman, Kyle Macdonald, Masanobu Shimada, Ake Rosenqvist, Ronny Schroeder, Laura Hess
Publications and Research
Shortly after the launch of ALOS PALSAR L-band SAR by the Japan Space Exploration Agency (JAXA), a program to develop an Earth Science Data Record (ESDR) for inundated wetlands was funded by NASA. Using established methodologies, extensive multi-temporal L-band ALOS ScanSAR data acquired bi-monthly by the PALSAR instrument onboard ALOS were used to classify the inundation state for South America for delivery as a component of this Inundated Wetlands ESDR (IW-ESDR) and in collaboration with JAXA’s ALOS Kyoto and Carbon Initiative science programme. We describe these methodologies and the final classification of the inundation state, then compared this with results …
Probabilistic Precipitation Estimation With A Satellite Product, Nir Y. Krakauer, Soni M. Pradhanang, Jeeban Panthi, Tarendra Lakhankar, Ajay K. Jha
Probabilistic Precipitation Estimation With A Satellite Product, Nir Y. Krakauer, Soni M. Pradhanang, Jeeban Panthi, Tarendra Lakhankar, Ajay K. Jha
Publications and Research
Satellite-based precipitation products have been shown to represent precipitation well over Nepal at monthly resolution, compared to ground-based stations. Here, we extend our analysis to the daily and subdaily timescales, which are relevant for mapping the hazards caused by storms as well as drought. We compared the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42RT product with individual stations and with the gridded APHRODITE product to evaluate its ability to retrieve different precipitation intensities. We find that 3B42RT, which is freely available in near real time, has reasonable correspondence with ground-based precipitation products on a daily timescale; rank …
The Use Of A Statistical Model Of Storm Surge As A Bias Correction For Dynamical Surge Models And Its Applicability Along The U.S. East Coast, Haydee Salmun, Andrea Molod
The Use Of A Statistical Model Of Storm Surge As A Bias Correction For Dynamical Surge Models And Its Applicability Along The U.S. East Coast, Haydee Salmun, Andrea Molod
Publications and Research
The present study extends the applicability of a statistical model for prediction of storm surge originally developed for The Battery, NY in two ways: I. the statistical model is used as a biascorrection for operationally produced dynamical surge forecasts, and II. the statistical model is applied to the region of the east coast of the U.S. susceptible to winter extratropical storms. The statistical prediction is based on a regression relation between the “storm maximum” storm surge and the storm composite significant wave height predicted ata nearby location. The use of the statistical surge prediction as an alternative bias correction for …
Role Of Engineering In Sustainable Water Management, Balázs M. Fekete, János J. Bogárdi
Role Of Engineering In Sustainable Water Management, Balázs M. Fekete, János J. Bogárdi
Publications and Research
The recognition of the limits of resources is almost as old as the realization that our planet is a sphere leading to concerns about sustainable resources management. Water resources in particular receive growing attention given its uneven distribution in many parts of the world. Engineering solutions to address water management challenges played significant roles in the past in areas such as access to clean water and sanitation, providing water for irrigation, offering protection against floods, allowing power generation, etc. Despite their proven benefits, engineering solutions are receiving increasing criticism due to their negative environmental and societal impacts and the high …
A Recipe For The Estimation Of Information Flow In A Dynamical System, Deniz Gencaga, Kevin H. Knuth, William B. Rossow
A Recipe For The Estimation Of Information Flow In A Dynamical System, Deniz Gencaga, Kevin H. Knuth, William B. Rossow
Publications and Research
Information-theoretic quantities, such as entropy and mutual information (MI), can be used to quantify the amount of information needed to describe a dataset or the information shared between two datasets. In the case of a dynamical system, the behavior of the relevant variables can be tightly coupled, such that information about one variable at a given instance in time may provide information about other variables at later instances in time. This is often viewed as a flow of information, and tracking such a flow can reveal relationships among the system variables. Since the MI is a symmetric quantity; an asymmetric …
Global Trends In Extreme Precipitation: Climate Models Versus Observations, Behzad Asadieh, Nir Y. Krakauer
Global Trends In Extreme Precipitation: Climate Models Versus Observations, Behzad Asadieh, Nir Y. Krakauer
Publications and Research
Precipitation events are expected to become substantially more intense under global warming, but few global comparisons of observations and climate model simulations are available to constrain predictions of future changes in precipitation extremes. We present a systematic global-scale comparison of changes in historical (1901–2010) annual-maximum daily precipitation between station observations (compiled in HadEX2) and the suite of global climate models contributing to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). We use both parametric and non-parametric methods to quantify the strength of trends in extreme precipitation in observations and models, taking care to sample them spatially and temporally …
Wetchimp-Wsl: Intercomparison Of Wetland Methane Emissions Models Over West Siberia, T. J. Bohn, J. R. Melton, A. Ito, T. Kleinen, R. Spahni, B. D. Stocker, B. Zhang, X. Zhu, R. Schroeder, M. V. Glagolev, S. Maksyutov, V. Brovkin, G. Chen, S. N. Denisov, A. V. Eliseev, A. Gallego-Sala, K. C. Mcdonald, M. A. Rawlins, W. J. Riley, Z. M. Subin, H. Tian, Q. Zhuang, J. O. Kaplan
Wetchimp-Wsl: Intercomparison Of Wetland Methane Emissions Models Over West Siberia, T. J. Bohn, J. R. Melton, A. Ito, T. Kleinen, R. Spahni, B. D. Stocker, B. Zhang, X. Zhu, R. Schroeder, M. V. Glagolev, S. Maksyutov, V. Brovkin, G. Chen, S. N. Denisov, A. V. Eliseev, A. Gallego-Sala, K. C. Mcdonald, M. A. Rawlins, W. J. Riley, Z. M. Subin, H. Tian, Q. Zhuang, J. O. Kaplan
Publications and Research
Wetlands are the world’s largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. …
Examination Of Geophysical Signatures Of Ethanol-Water Mixtures In A Homogeneous Sand Column Using Ground Penetrating Radar And Time-Domain Reflectometry, Angelo Lampousis, Neil Terry, Lee Slater
Examination Of Geophysical Signatures Of Ethanol-Water Mixtures In A Homogeneous Sand Column Using Ground Penetrating Radar And Time-Domain Reflectometry, Angelo Lampousis, Neil Terry, Lee Slater
Publications and Research
In recent years there has been an increase in the frequency of incidents involving ethanol-blended gasoline affecting the groundwater. Near-surface geophysical methods hold promise for site characterization at ethanol contaminated sites. We attempted to record the broadband dielectric properties of ethanol at various concentrations as it was circulating through a closed tank containing either sand or a sand-clay mixture. Two high frequency GPR antennas were positioned symmetrically on either side of the sample holder to obtain transmission measurements. In the first part of the experiment we used a sample consisting of sand. In the second part of the experiment we …