De Lannoy G. J. M., Reichle R. H., Peng J. Z., Kerr Yann, Castro R., Kim E. J., Liu Q. (2015). Converting between SMOS and SMAP level-1 brightness temperature observations over nonfrozen land. Ieee Geoscience and Remote Sensing Letters, 12 (9), p. 1908-1912. ISSN 1545-598X.
Titre du document
Converting between SMOS and SMAP level-1 brightness temperature observations over nonfrozen land
De Lannoy G. J. M., Reichle R. H., Peng J. Z., Kerr Yann, Castro R., Kim E. J., Liu Q.
Source
Ieee Geoscience and Remote Sensing Letters, 2015,
12 (9), p. 1908-1912 ISSN 1545-598X
The Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) missions provide Level-1 brightness temperature (Tb) observations that are used for global soil moisture estimation. However, the nature of these Tb data differs: the SMOS Tb observations contain atmospheric and select reflected extraterrestrial ("Sky") radiation, whereas the SMAP Tb data are corrected for these contributions, using auxiliary near-surface information. Furthermore, the SMOS Tb observations are multiangular, whereas the SMAP Tb is measured at 40 degrees incidence angle only. This letter discusses how SMOS Tb, SMAP Tb, and radiative transfer modeling components can be aligned in order to enable a seamless exchange of SMOS and SMAP Tb data in soil moisture retrieval and assimilation systems. The aggregated contribution of the atmospheric and reflected Sky radiation is, on average, about 1 K for horizontally polarized Tb and 0.5 K for vertically polarized Tb at 40 degrees incidence angle, but local and short-term values regularly exceed 5 K.
