Seasonal dependence of SMAP radiometer-based soil moisture performance as observed over core validation sites

A. Colliander, T. J. Jackson, S. K. Chan, P. O'Neill, R. Bindlish, M. H. Cosh, T. Caldwell, J. P. Walker, A. Berg, H. McNairn, M. Thibeault, J. Martinez-Fernandez, K. H. Jensen, J. Asanuma, M. S. Seyfried, D. D. Bosch, P. J. Starks, C. Holifield Collins, J. H. Prueger, Z. SuS. H. Yueh

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther


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.

Original languageEnglish
Title of host publicationIGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium
PublisherIEEE, Institute of Electrical and Electronics Engineers
Number of pages4
ISBN (Electronic)9781538691540
Publication statusPublished - 2019
EventIEEE International Geoscience and Remote Sensing Symposium 2019 - Yokohama, Japan
Duration: 28 Jul 20192 Aug 2019
Conference number: 39th (Website) (Proceedings)


ConferenceIEEE International Geoscience and Remote Sensing Symposium 2019
Abbreviated titleIGARSS 2019
Internet address


  • core validation site
  • SMAP
  • Soil Moisture

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