TY - JOUR
T1 - Forward simulation of multi-frequency microwave brightness temperature over desert soils in Kuwait and comparison with satellite observations
AU - AlJassar, Hala K.
AU - Temimi, Marouane
AU - Entekhabi, Dara
AU - Petrov, Peter
AU - AlSarraf, Hussain
AU - Kokkalis, Panagiotis
AU - Roshni, Nair
N1 - Funding Information:
The authors are thankful to the Kuwait Foundation for the Advancement of Sciences (KFAS) for sponsoring the work of this paper under Project 2012141301 and P21544SP01 and faithfully grateful to Kuwait University (KU) for their continuous support. Being an international partner with NASA SMAP Cal/Val science team, we also want to acknowledge NASA (JPL) with all their help in accessing SMAP satellite data. Shafiullah Mohideen is acknowledged for his help in formatting the soil map of Kuwait. This research is funded by the Kuwait Foundation for the Advancement of Sciences (KFAS) for sponsoring the work of this paper under the following title: "Calibration and Validation of NASA (SMAP) Satellite for the Retrieval of Soil Moisture and the Application to Environmental Modeling in Kuwait with project grand numbers phase I 2012141301 and phase II P21544SP01.
Publisher Copyright:
© 2019 by the authors.
PY - 2019
Y1 - 2019
N2 - In this study, we address the variations of bare soil surface microwave brightness temperatures and evaluate the performance of a dielectric mixing model over the desert of Kuwait. We use data collected in a field survey and data obtained from NASA Soil Moisture Active Passive (SMAP), European Space Agency Soil Moisture and Ocean Salinity (SMOS), Advanced Microwave Scanning Radiometer 2 (AMSR2), and Special Sensor Microwave/Imager (SSM/I). In situ measurements are collected during two intensive field campaigns over bare, flat, and homogeneous soil terrains in the desert of Kuwait. Despite the prevailing dry desert environment, a large range of soil moisture values was monitored, due to precedent rain events and subsequent dry down. The mean relative difference (MRD) is within the range of ±0.005 m3·m-3 during the two sampling days. This reflects consistency of soil moisture in space and time. As predicted by the model, the higher frequency channels (18 to 19 GHz) demonstrate reduced sensitivity to surface soil moisture even in the absence of vegetation, topography and heterogeneity. In the 6.9 to 10.7 GHz range, only the horizontal polarization is sensitive to surface soil moisture. Instead, at the frequency of 1.4 GHz, both polarizations are sensitive to soil moisture and span a large dynamic range as predicted by the model. The error statistics of the difference between observed satellite brightness temperature (Tb) (excluding SMOS data due to radio frequency interference, RFI) and simulated brightness temperatures (Tbs) show values of Root Mean Square Deviation (RMSD) of 5.05 K at vertical polarization and 4.88 K at horizontal polarization. Such error could be due to the performance of the dielectric mixing model, soil moisture sampling depth and the impact of parametrization of effective temperature and roughness.
AB - In this study, we address the variations of bare soil surface microwave brightness temperatures and evaluate the performance of a dielectric mixing model over the desert of Kuwait. We use data collected in a field survey and data obtained from NASA Soil Moisture Active Passive (SMAP), European Space Agency Soil Moisture and Ocean Salinity (SMOS), Advanced Microwave Scanning Radiometer 2 (AMSR2), and Special Sensor Microwave/Imager (SSM/I). In situ measurements are collected during two intensive field campaigns over bare, flat, and homogeneous soil terrains in the desert of Kuwait. Despite the prevailing dry desert environment, a large range of soil moisture values was monitored, due to precedent rain events and subsequent dry down. The mean relative difference (MRD) is within the range of ±0.005 m3·m-3 during the two sampling days. This reflects consistency of soil moisture in space and time. As predicted by the model, the higher frequency channels (18 to 19 GHz) demonstrate reduced sensitivity to surface soil moisture even in the absence of vegetation, topography and heterogeneity. In the 6.9 to 10.7 GHz range, only the horizontal polarization is sensitive to surface soil moisture. Instead, at the frequency of 1.4 GHz, both polarizations are sensitive to soil moisture and span a large dynamic range as predicted by the model. The error statistics of the difference between observed satellite brightness temperature (Tb) (excluding SMOS data due to radio frequency interference, RFI) and simulated brightness temperatures (Tbs) show values of Root Mean Square Deviation (RMSD) of 5.05 K at vertical polarization and 4.88 K at horizontal polarization. Such error could be due to the performance of the dielectric mixing model, soil moisture sampling depth and the impact of parametrization of effective temperature and roughness.
KW - Desert
KW - Dielectric mixing model
KW - Field campaign
KW - Satellite microwave brightness temperature
KW - Soil roughness
KW - Volumetric soil moisture (VSM)
UR - http://www.scopus.com/inward/record.url?scp=85070941517&partnerID=8YFLogxK
U2 - 10.3390/rs11141647
DO - 10.3390/rs11141647
M3 - Article
SN - 2072-4292
VL - 11
JO - Remote Sensing
JF - Remote Sensing
IS - 14
M1 - 1647
ER -