Release of the new SMOS-IC version 2 (V2) of SM and L-VOD products

Since the release of the first version of SMOS-IC V105, several improvements have been applied to the SMOS-IC algorithm, leading to the production of the version 2 (V2), based on a collaboration between INRAE and China Scholarship Council. Major improvements were based on the concept that VOD has low time variations over short time periods (Wigneron et al., 2000; Tian et al., 2018). To implement this multi-orbit concept, the optimization processing of the a priori information on VOD to constrain the retrievals has been modified in SMOS-IC V2: to retrieve VOD at a date t, previously retrieved VOD values (over a period of 10 days before date t) are used to initialize the first guess value of VOD (VODⁱⁿⁱ) in the cost function. A more detailed description of the SMOS-IC V2 retrieval algorithm will be given in Wigneron et al., 2020(RSE, Submitted). It should be noted that clear improvements in SMOS-IC V2 are obtained for both SM and VOD. An in-depth analysis and inter-comparison between L-VOD products and other frequency VOD is ongoing (Li et al., 2020 (RSE, submitted)).

References:

• Wigneron, J.P., Li, X., Frappart, F., Fan, L., Al-Yaari, A., De Lannoy, G., Liu, X., Wang, M., Le Masson, E., & Moisy, M. (Submitted). Overview of the SMOS-IC data record of soil moisture and L-VOD: historic development, applications and perspectives. Remote Sensing of Environment.
• Li, X., Wigneron, J.P., Frappart, F., Fan, L., Philippe, C. et al (Submitted). Global-scale assessment and inter-comparison of recently developed/reprocessed microwave satellite vegetation optical depth products. Remote Sensing of Environment.
• Li X, Al-Yaari A, Schwank M, et al. Compared performances of SMOS-IC soil moisture and vegetation optical depth retrievals based on Tau-Omega and Two-Stream microwave emission models[J]. Remote Sensing of Environment, 2020, 236: 111502.
• Li, X., Wigneron, J.-P., Frappart, F., Fan, L., Wang, M., Liu, X., Al-Yaari, A., Moisy, C., 2020. Development and validation of the SMOS-IC version 2 soil moisture product. In: IGARSS 2020-2020 IEEE International Geoscience and Remote Sensing Symposium. IEEE.