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de Matthaeis, P., Soldo, Y., Le Vine, D.M. (10-July-16). Aquarius is an L-band active/passive sensor designed to globally map sea surface salinity from space. Two instruments, a radar scatterometer and a radiometer, observe the same surface footprint almost simultaneously. The radiometer is the primary instrument for sensing sea surface salinity (SSS), while the scatterometer is included to provide a correction for sea surface roughness, which is a primary source of error in the salinity retrieval. Misra, S., Piepmeier, J.R., Peng, J., Mohammed, P., Hudson, D., De Amici, G., Dinnat, E., Le Vine, D., Bindlish, R., and Jackson, T. (10-July-16). In this paper we discuss the steps taken for the calibration and validation of the Soil Moisture Active Passive (SMAP) L-band radiometer. We discuss the use of multiple vicarious sources such as the global ocean mean and celestial cold-sky emissions along with various spacecraft maneuvers to calibrate out gain, offset, antenna pattern of the radiometer. We present initial validation comparison of SMAP brightness temperatures with other L-band missions. Burgin, M., and van Zyl, J. (10-July-16). State of the art soil moisture radar retrieval algorithms traditionally depend on substantial amounts of ancillary data, such as land cover and soil texture/composition maps, to parametrize complex electromagnetic models. In this work, we pursue an existing empirical approach as an alternative; it expresses radar backscatter of a vegetated scene as a linear function of soil moisture, thus reducing the dependence on ancillary data. We use 2.5 years of L-band Aquarius radar and radiometer derived soil moisture data to determine the two unknowns of the linear model function on a global scale. Blindish, R., Jackson, T., Peipmeier, J.R., Yueh, S., and Kerr, Y. (10-July-16). Verifying the calibration of the SMAP radiometer over land observations is an important mission requirement. Inter-comparison of L-band brightness temperature observations from different satellites (SMAP, SMOS and Aquarius) is a useful tool for radiometer calibration. Yueh, S., Fore, A., Tang, W., Akiko, H., and Stiles, B. (10-July-16). We investigated the use of L-band active and passive microwave data from the Soil Moisture Active Passive (SMAP) observatory for remote sensing of ocean surface winds during hurricanes. We analyzed the dependence of SMAP data on ocean surface wind speed and direction, and found excellent consistency with the geophysical model functions developed for the Aquarius L-band radar/radiometer although the spatial resolutions of SMAP and Aquarius are distinctly different. Dinnat, E., and Le Vine, D. (10-July-16). Three L-band radiometers have been observing the Earth in order to retrieve soil moisture and ocean salinity. They use different instrument configurations and calibration and retrieval algorithms. In any case, the brightness temperature retrieved at the Earth surface should be consistent between all instruments. One reason for inconsistency would be the use of different approaches for the instrument calibration or the use of different models to retrieve surface brightness temperature. We report on the different approaches used for the SMOS, SMAP and Aquarius instruments and their impact on the observations consistency. Du, Y., Shi, J.C., Yin, X., and Xu, Y. (10-July-16). Sea surface salinity (SSS) has a profounding influence on the the exchanges of matter and energy at the air-ocean interface. It is also a driving force for ocean circulations. The capability of accurate measurement of SSS with high spatial and temporal resolution shall be a desirable boost to the global climate models. The scientific missions Soil Moisture and Ocean Salinity (SMOS) [1] and Aquarius [2] are specific to this end.