caa a22 4500 606162615 CHVBK 20210128100640.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s10291-014-0383-7 doi (NATIONALLICENCE)springer-10.1007/s10291-014-0383-7 Using geodetic GPS receivers to measure vegetation water content [Elektronische Daten] [Wei Wan, Kristine Larson, Eric Small, Clara Chew, John Braun] A GPS-based method is presented to measure vegetation water content. Commercially available geodetic-quality GPS receivers and antennas are used. The method is tested using GPS measurements collected over three field seasons. The GPS data are compared with in situ data for three plant types: desert grass, wheat, and alfalfa. The GPS retrievals of vegetation water content are based on the GPS signal-to-noise ratio (SNR) data. Instrumental issues that affect the SNR data are discussed, particularly satellite transmit power variations, footprint variations, and temperature effects. The amplitudes of the SNR data show a nearly linear relationship to the water content in grasses (0-0.5kg/m2) and wheat crops (0-0.9kg/m2). As predicted by theory, this simple linear relationship breaks down in vegetation with heavy water content, such as alfalfa. The field results are consistent with forward model predictions, whose effect restricts the use of this simple linear model for vegetation to water content of less than ~1kg/m2. Springer-Verlag Berlin Heidelberg, 2014 GNSS nationallicence GPS nationallicence SNR nationallicence Multipath nationallicence Reflections nationallicence Vegetation water content nationallicence Wan Wei School of Earth and Space Sciences, Peking University, Beijing, China aut Larson Kristine Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, USA aut Small Eric Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA aut Chew Clara Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA aut Braun John COSMIC, University Corporation for Atmospheric Research, Boulder, CO, USA aut GPS Solutions Springer Berlin Heidelberg 19/2(2015-04-01), 237-248 1080-5370 19:2<237 2015 19 10291 https://doi.org/10.1007/s10291-014-0383-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10291-014-0383-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Wan Wei School of Earth and Space Sciences, Peking University, Beijing, China aut NATIONALLICENCE 700 1- Larson Kristine Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, USA aut NATIONALLICENCE 700 1- Small Eric Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA aut NATIONALLICENCE 700 1- Chew Clara Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA aut NATIONALLICENCE 700 1- Braun John COSMIC, University Corporation for Atmospheric Research, Boulder, CO, USA aut NATIONALLICENCE 773 0- GPS Solutions Springer Berlin Heidelberg 19/2(2015-04-01), 237-248 1080-5370 19:2<237 2015 19 10291