TY - JOUR
T1 - Impact of soil permittivity and temperature profile on L-Band microwave emission of frozen soil
AU - Zheng, Donghai
AU - Li, X.
AU - Zhao, T.
AU - Wen, J.
AU - Velde, R. Van Der
AU - Schwank, M.
AU - Wang, X.
AU - Wang, Z.
AU - Su, Z.
N1 - Funding Information:
Manuscript received March 24, 2020; revised July 1, 2020 and August 14, 2020; accepted September 12, 2020. Date of publication September 28, 2020; date of current version April 22, 2021. This work was supported in part by the National Natural Science Foundation of China under Grant 41871273, Grant 41671355, Grant 41530529, and Grant 41630856, and in part by the Netherlands Organization for Scientific Research under Project ALW-GO/14-29. (Corresponding author: Donghai Zheng.) Donghai Zheng is with the Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, National Tibetan Plateau Data Center, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China (e-mail: zhengd@itpcas.ac.cn).
Publisher Copyright:
© 1980-2012 IEEE.
PY - 2021/5/1
Y1 - 2021/5/1
N2 - An unexplored aspect of L-band microwave emission is the impact of soil moisture and soil temperature (SMST) profile dynamics on diurnal brightness temperature (TB) signatures of frozen soil. This study investigates this effect by comparing the TB simulations of layered (TB,l) and uniform (TB,u) soils using a newly developed integrated land emission model. The multilayer Wilheit model and the single-layer Fresnel model are adopted to compute the smooth soil reflectivity for the layered and uniform soils, respectively. A four-phase dielectric mixing model is used to calculate the soil permittivity (ϵₛ). A data set of concurrent ELBARA-III TB and SMST profile measurements performed in a seasonally frozen Tibetan meadow ecosystem is used for the analysis. The simulated TB,l considering SMST profile information captures well the ELBARA-III measurements with low biases (łe 6 K) and high correlations (R²≥ 0.88). TB,u produced based on the Fresnel model using the soil moisture of 2.5 cm is more consistent with the TB,l. The sensitivity test of averaging SMST profile below 2.5 cm leads to maximum differences of 2 K in TB,l simulations, indicating that the TB variations are primary dominated by the SMST dynamics at the surface layer. A sensitivity test of the Wilheit model to different ϵₛ parameterizations shows that the dielectric model of Zhang et al. is comparable to the four-phase dielectric model in simulating TB,l, while the Mironov et al.'s model demonstrates larger biases for frozen soil with, on average, 2.2% clay content, 49.7% sand content, and a bulk density of 1 g·cm⁻³.
AB - An unexplored aspect of L-band microwave emission is the impact of soil moisture and soil temperature (SMST) profile dynamics on diurnal brightness temperature (TB) signatures of frozen soil. This study investigates this effect by comparing the TB simulations of layered (TB,l) and uniform (TB,u) soils using a newly developed integrated land emission model. The multilayer Wilheit model and the single-layer Fresnel model are adopted to compute the smooth soil reflectivity for the layered and uniform soils, respectively. A four-phase dielectric mixing model is used to calculate the soil permittivity (ϵₛ). A data set of concurrent ELBARA-III TB and SMST profile measurements performed in a seasonally frozen Tibetan meadow ecosystem is used for the analysis. The simulated TB,l considering SMST profile information captures well the ELBARA-III measurements with low biases (łe 6 K) and high correlations (R²≥ 0.88). TB,u produced based on the Fresnel model using the soil moisture of 2.5 cm is more consistent with the TB,l. The sensitivity test of averaging SMST profile below 2.5 cm leads to maximum differences of 2 K in TB,l simulations, indicating that the TB variations are primary dominated by the SMST dynamics at the surface layer. A sensitivity test of the Wilheit model to different ϵₛ parameterizations shows that the dielectric model of Zhang et al. is comparable to the four-phase dielectric model in simulating TB,l, while the Mironov et al.'s model demonstrates larger biases for frozen soil with, on average, 2.2% clay content, 49.7% sand content, and a bulk density of 1 g·cm⁻³.
KW - ITC-ISI-JOURNAL-ARTICLE
UR - https://ezproxy2.utwente.nl/login?url=https://doi.org/10.1109/TGRS.2020.3024971
UR - https://ezproxy2.utwente.nl/login?url=https://library.itc.utwente.nl/login/2020/isi/zheng_imp.pdf
U2 - 10.1109/TGRS.2020.3024971
DO - 10.1109/TGRS.2020.3024971
M3 - Article
SN - 1558-0644
VL - 59
SP - 4080
EP - 4093
JO - IEEE transactions on geoscience and remote sensing
JF - IEEE transactions on geoscience and remote sensing
IS - 5
M1 - 9207846
ER -
