HR: 0800h
AN: H31A-0129    [Abstracts]
TI: Satellite Estimation of Daily Land Surface Water Vapor Pressure Deficit from AMSR- E
AU: * Jones, L A
EM: lucas@ntsg.umt.edu
AF: Flathead Lake Biological Station, Div. of Biological Sciences, The University of Montana, 32125 Bio Station Lane, Polson, MT 59860-6815, United States
AU: * Jones, L A
EM: lucas@ntsg.umt.edu
AF: Numerical Terradynamic Simulation Group, College of Forestry and Conservation, The University of Montana, 32 Campus Drive, Missoula, MT 59812, United States
AU: Kimball, J S
EM: johnk@ntsg.umt.edu
AF: Flathead Lake Biological Station, Div. of Biological Sciences, The University of Montana, 32125 Bio Station Lane, Polson, MT 59860-6815, United States
AU: Kimball, J S
EM: johnk@ntsg.umt.edu
AF: Numerical Terradynamic Simulation Group, College of Forestry and Conservation, The University of Montana, 32 Campus Drive, Missoula, MT 59812, United States
AU: McDonald, K C
EM: kyle.mcdonald@jpl.nasa.gov
AF: Jet Propulsion Laboratory,California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Chan, S K
EM: steven.k.chan@jpl.nasa.gov
AF: Jet Propulsion Laboratory,California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Njoku, E G
EM: eni.g.njoku@jpl.nasa.gov
AF: Jet Propulsion Laboratory,California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Oechel, W C
EM: oechel@sunstroke.sdsu.edu
AF: Global Change Research Group, Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, United States
AB: Vapor pressure deficit (VPD) is a key variable for monitoring land surface water and energy exchanges, and estimating plant water stress. Multi-frequency day/night brightness temperatures from the Advanced Microwave Scanning Radiometer on EOS Aqua (AMSR-E) were used to estimate daily minimum and average near surface (2 m) air temperatures across a North American boreal-Arctic transect. A simple method for determining daily mean VPD (Pa) from AMSR-E air temperature retrievals was developed and validated against observations across a regional network of eight study sites ranging from boreal grassland and forest to arctic tundra. The method assumes that the dew point and minimum daily air temperatures tend to equilibrate in areas with low night time temperatures and relatively moist conditions. This assumption was tested by comparing the VPD algorithm results derived from site daily temperature observations against results derived from AMSR-E retrieved temperatures alone. An error analysis was conducted to determine the amount of error introduced in VPD estimates given known levels of error in satellite retrieved temperatures. Results indicate that the assumption generally holds for the high latitude study sites except for arid locations in mid-summer. VPD estimates using the method with AMSR-E retrieved temperatures compare favorably with site observations. The method can be applied to land surface temperature retrievals from any sensor with day and night surface or near-surface thermal measurements and shows potential for inferring near-surface wetness conditions where dense vegetation may hinder surface soil moisture retrievals from low-frequency microwave sensors. This work was carried out at The University of Montana, at San Diego State University, and at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0480 Remote sensing
DE: 0495 Water/energy interactions (1878)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1655 Water cycles (1836)
SC: Hydrology [H]
MN: 2007 Fall Meeting