학술논문
Seasonal Dependence of SMAP Radiometer-Based Soil Moisture Performance as Observed Over Core Validation Sites
Document Type
Conference
Author
Colliander, A.; Jackson, T.J.; Chan, S.K.; O'Neill, P.; Bindlish, R.; Cosh, M. H.; Caldwell, T.; Walker, J. P.; Berg, A.; McNairn, H.; Thibeault, M.; Martinez-Fernandez, J.; Jensen, K.H.; Asanuma, J.; Seyfried, M.S.; Bosch, D.D.; Starks, P.J.; Holifield Collins, C.; Prueger, J.H.; Su, Z.; Yueh, S. H.
Source
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium Geoscience and Remote Sensing Symposium, IGARSS 2019 - 2019 IEEE International. :5320-5323 Jul, 2019
Subject
Language
ISSN
2153-7003
Abstract
The NASA SMAP (Soil Moisture Active Passive) mission provides a global coverage of soil moisture measurements based on its L-band microwave radiometer every 2-3 days at about 40 km resolution. The soil moisture retrieval algorithms model the brightness temperature as a function of soil moisture, surface conditions and vegetation. External data sources inform the algorithms about the surface conditions and vegetation, which enable the retrieval of soil moisture. The inversion process contains uncertainties related to radiometer measurements, forward model assumptions and ancillary data sources. This study focuses on the uncertainties that depend on the seasonal evolution of the surface conditions and vegetation. The study compares the SMAP and core validation site (CVS) soil moisture values over a period of four years to extract the evolution of performance metrics over time. The analysis showed that most CVS that include managed agriculture exhibit significant time-dependent seasonal bias. This bias was linked to seasonal temperature cycle, which is a proxy to several features that can cause seasonally dependent errors in the SMAP product.