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Assembly and Assessment of ASCAT Scatterometer Data for Continuing Global Vegetation State Monitoring: Comparison with SeaWinds-on-QuikSCAT and Vegetation Response to Seasonal Drought
Ronny
Schroeder, City College of New York, ronny.schroder@gmail.com
Kyle
McDonald, The City College of New York, kmcdonald2@ccny.cuny.edu
(Presenter)
R
Scott
Dunbar, JPL, roy.s.dunbar@jpl.nasa.gov
Marzi
Azarderakhsh, City College of New York, mazarderakhsh@ccny.cuny.edu
Nicholas
Steiner, City College of New York, nick.steiner@gmail.com
John
S
Kimball, University of Montana, johnk@ntsg.umt.edu
Reiner
Zimmermann, University of Hohenheim, dr.reiner.zimmermann@uni-hohenheim.de
Manfred
Kuppers, University of Hohenheim, manfred.kueppers@uni-hohenheim.de
The C-band advanced scatterometer instrument (ASCAT) onboard the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Metop satellite is the current data source for meteorologists who rely on near real-time ocean surface wind field observations to provide accurate weather forecasts. Furthermore, with the demise of the Ku-band SeaWind-on-QuikSCAT scatterometer (QSCAT) in 2009, ASCAT is also the only satellite-borne radar providing high-repeat (1-3 days) global vegetation state monitoring. We investigate the effects of land cover and seasonal vegetation development (phenology) on concurrent backscatter measurements made on a global basis by the ASCAT and the QSCAT instruments between November 2008 and 2009. A method for the normalization of the ASCAT backscatter dependency on incidence angle is applied. The ASCAT backscatter is then normalized to a look angle of 54 degrees, equal to that of QSCAT. A radiometric slope correction is applied based on a digital elevation model and satellite viewing geometry (i.e. azimuth and altitude). We analyze 4-years of incidence angle normalized ASCAT backscatter and NEXRAD precipitation data over the contiguous US. Large negative peak growing season backscatter anomalies are evident over the US during 2011 and 2012. The drought patterns observed were related to negative growing season precipitation with land cover predicting where drought-related impacts on above-ground net primary production should be expected. During periods of acute drought, diurnal backscatter differences were reduced (in some cases reversed) pointing to inadequate nocturnal leave recovery. The results indicate that C-band, vv-polarized and incidence angle normalized ASCAT backscatter data may provide an important geophysical tool capable of identifying drought related vegetation patterns .
Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Presentation Type: Poster
Session: Poster Session 1-A
(Tue 11:00 AM)
Associated Project(s):
Poster Location ID: 2
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