TY  - JOUR
AU  - Jonard, F.
AU  - Weihermüller, L.
AU  - Jadoon, K.Z.
AU  - Schwank, M.
AU  - Vereecken, H.
AU  - Lambot, S.
TI  - Mapping Field-Scale Soil Moisture With L-Band Radiometer and Ground-Penetrating Radar Over bare Soil
JO  - IEEE transactions on geoscience and remote sensing
VL  - 49
SN  - 0196-2892
CY  - New York, NY
PB  - IEEE
M1  - PreJuSER-16234
SP  - 2863 - 2876
PY  - 2011
N1  - The authors would like to thank Gamma Remote Sensing and Consulting AG for providing the radiometer antenna, F. Andre, M. Dimitrov, D. Moghadas, R. Harms, and N. Hermes of Forschungszentrum Julich GmbH for their assistance with fieldwork, and the anonymous reviewers for their constructive comments. The JULBARA radiometer was funded by "Terrestrial Environmental Observatories" (TERENO) funded by the German Federal Ministry of Education and Research (BMBF).This work was supported in part by the German Research Foundation (DFG) in the frame of the Transregional Collaborative Research Centre 32 and in part by the Fonds National de la Recherche Scientifique (Belgium).
AB  - Accurate estimates of surface soil moisture are essential in many research fields, including agriculture, hydrology, and meteorology. The objective of this study was to evaluate two remote-sensing methods for mapping the soil moisture of a bare soil, namely, L-band radiometry using brightness temperature and ground-penetrating radar (GPR) using surface reflection inversion. Invasive time-domain reflectometry (TDR) measurements were used as a reference. A field experiment was performed in which these three methods were used to map soil moisture after controlled heterogeneous irrigation that ensured a wide range of water content. The heterogeneous irrigation pattern was reasonably well reproduced by both remote-sensing techniques. However, significant differences in the absolute moisture values retrieved were observed. This discrepancy was attributed to different sensing depths and areas and different sensitivities to soil surface roughness. For GPR, the effect of roughness was excluded by operating at low frequencies (0.2-0.8 GHz) that were not sensitive to the field surface roughness. The root mean square (rms) error between soil moisture measured by GPR and TDR was 0.038 m(3) . m(-3). For the radiometer, the rms error decreased from 0.062 (horizontal polarization) and 0.054 (vertical polarization) to 0.020 m(3) . m(-3) (both polarizations) after accounting for roughness using an empirical model that required calibration with reference TDR measurements. Monte Carlo simulations showed that around 20% of the reference data were required to obtain a good roughness calibration for the entire field. It was concluded that relatively accurate measurements were possible with both methods, although accounting for surface roughness was essential for radiometry.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000293709200005
DO  - DOI:10.1109/TGRS.2011.2114890
UR  - https://juser.fz-juelich.de/record/16234
ER  -