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David M Sumner
Science and Products
A simple method for partitioning total solar radiation into diffuse/direct components in the United States
Solar radiation is a major sustainable and clean energy resource, and use of solar radiation is expected to increase. The utilization efficiency of solar energy varies with the relative proportions of the direct and diffuse components that compose total solar radiation and with the slope and aspect of the irradiated surface. The purpose of this...Fan, Jingjing; Huang, Qiang; Sumner, David M.; Wang, Dingbao
Estimating belowground carbon stocks in isolated wetlands of the Northern Everglades Watershed, central Florida, using ground penetrating radar (GPR) and aerial imagery
Peat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. While isolated freshwater wetlands in temperate and tropical biomes account for more than 20% of the global peatland C stock, most studies of wetland soil C have occurred in expansive peatlands in northern boreal and subarctic biomes....McClellan, Matthew; Comas, Xavier; Hinkle, Ross; Sumner, David M.
Use of eddy-covariance methods to "calibrate" simple estimators of evapotranspiration
Direct measurement of actual evapotranspiration (ET) provides quantification of this large component of the hydrologic budget, but typically requires long periods of record and large instrumentation and labor costs. Simple surrogate methods of estimating ET, if â€œcalibratedâ€ to direct measurements of ET, provide a reliable means to quantify ET...Sumner, David M.; Geurink, Jeffrey S.; Swancar, Amy
A comparison of models for estimating potential evapotranspiration for Florida land cover types
We analyzed observed daily evapotranspiration (DET) at 18 sites having measured DET and ancillary climate data and then used these data to compare the performance of three common methods for estimating potential evapotranspiration (PET): the Turc method (Tc), the Priestley-Taylor method (PT) and the Penman-Monteith method (PM). The sites were...Douglas, Ellen M.; Jacobs, Jennifer M.; Sumner, David M.; Ray, Ram L.
Measurement and simulation of evapotranspiration at a wetland site in the New Jersey Pinelands
Evapotranspiration (ET) was monitored above a wetland forest canopy dominated by pitch-pine in the New Jersey Pinelands during November 10, 2004-February 20, 2007, using an eddy-covariance method. Twelve-month ET totals ranged from 786 to 821 millimeters (mm). Minimum and maximum ET rates occurred during December-February and in July, respectively...Sumner, David M.; Nicholson, Robert S.; Clark, Kenneth L.
Variability of albedo and utility of the MODIS albedo product in forested wetlands
Albedo was monitored over a two-year period (beginning April 2008) at three forested wetland sites in Florida, USA using up- and down-ward facing pyranometers. Water level, above and below land surface, is the primary control on the temporal variability of daily albedo. Relatively low reflectivity of water accounts for the observed reductions in...Sumner, David M.; Wu, Qinglong; Pathak, Chandra S.
Calibration of GOES-derived solar radiation data using a distributed network of surface measurements in Florida, USA
Solar radiation data are critically important for the estimation of evapotranspiration. Analysis of visible-channel data derived from Geostationary Operational Environmental Satellites (GOES) using radiative transfer modeling has been used to produce spatially- and temporally-distributed datasets of solar radiation. An extensive network of (...Babcock, Roger W.; Walton, Raymond; Sumner, David M.; Pathak, Chandra S.; Mecikalski, John R.; Paech, Simon J.; Wu, Qinglong; Sangoyomi, Taiye
Estimating changes in heat energy stored within a column of wetland surface water and factors controlling their importance in the surface energy budget
Changes in heat energy stored within a column of wetland surface water can be a considerable component of the surface energy budget, an attribute that is demonstrated by comparing changes in stored heat energy to net radiation at seven sites in the wetland areas of southern Florida, including the Everglades. The magnitude of changes in stored heat...Shoemaker, W. Barclay; Sumner, David M.; Castillo, Adrian
Water-level maps of the alluvial aquifer, Northwestern Mississippi, April 1983
Water levels were measured in about 500 wells in the Mississippi River valley alluvial aquifer in northwestern Mississippi during April 1983. Ground-water levels have declined in some areas in recent years as a result of heavy irrigation pumpage from this aquifer. Near the areas of principal recharge, along the major rivers, and near the Bluff...Sumner, David M.