Soil Moisture Active and Passive (SMAP) Mission: An L-band combined radar-radiometer mission for measurement of
surface soil moisture and freeze-thaw state
Kyle
McDonald, Jet Propulsion Lab, California Institute of Technology, kyle.mcdonald@jpl.nasa.gov
(Presenting)
John
Kimball, The University of Montana, johnk@ntsg.umt.edu
Eni
Njoku, Jet Propulsion Lab, California Institute of Technology, eni.njoku@jpl.nasa.gov
Dara
Entekhabi, Massachusetts Institute of Technology, darae@mit.edu
Peggy
O'Neill, NASA Goddard Space Flight Center, peggy.e.oneill@nasa.gov
NASA’s Soil Moisture Active/Passive (SMAP) mission, now under development and currently planned for launch in the 2014-2015 time frame, will use a combined radiometer and high-resolution radar to measure surface soil moisture and freeze/thaw state globally providing new opportunities for scientific advances and societal benefits. Major science objectives of SMAP support the understanding of processes linking terrestrial water, energy and carbon cycles, the quantification of net carbon flux, and the extension of capabilities for weather and climate prediction models. Soil moisture is a key control on evaporation and transpiration at the land-atmosphere boundary. The amount of surface moisture and its status define a surface hydrospheric state that is key to linking terrestrial water and carbon cycles and a key determinant of the terrestrial carbon cycle. In addition, the SMAP mission has the potential to enable a diverse range of applications including drought and flood guidance, weather forecasting, climate predictions, human health risk, defense systems, and agricultural productivity estimation.
The SMAP instrument package incorporates an L-band (1.26 GHz) radar and an L-band (1.41 GHz) radiometer that share a single feedhorn and parabolic mesh reflector dish antenna. The 6 meter diameter reflector has a constant off-nadir look angle and rotates about the nadir axis at 14.6 rpm, providing a conically scanned antenna beam and footprint with a surface incidence angle of approximately 40 degrees. The reflector dish provides a radiometer footprint of 40 km. Range and Doppler discrimination are employed to process the radar backscatter to an enhanced 1 to 3 km spatial resolution, providing high resolution backscatter measurements within the 40-km radiometer footprint. The rational is to combine the attributes of the radar and radiometer observations in terms of their spatial resolution and sensitivity to soil moisture, surface roughness, and vegetation. The constant look angle scanning antenna geometry allows acquisition of data across a 1000-km wide swath and accurate repeat-pass estimation surface moisture and hydrologic status every 2-3 days globally.
This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.
Presentation Type: Poster
Poster Session: Orbital and Suborbital Missions
NASA TE Funded Awards Represented:
NONE: Related Activity or Previously Funded TE Award