Satellite retrieval of convective cloud base temperature based on the NPP/VIIRS Imager

The advent of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-Orbiting Partnership (NPP) satellite provided a quantum jump in the satellite capabilities of retrieving cloud properties, because it nearly tripled the resolution in the thermal channels (375m). This allowed us to develop a methodology for retrieving convective cloud base temperature (Tb) and validate it over the Atmospheric System Research (ASR) Southern Great Plains (SGP) site for the satellite early afternoon overpass time. The standard error of the Tb retrieval was only 1.1°C. The knowledge of Tb allows the calculation of cloud base height and the depth of the boundary layer. Once Tb is known, the vapor mixing ratio in the well mixed boundary layer can be calculated. This calculation was shown to have an accuracy of about 10%. This is a major improvement with respect to hyperspectral capabilities of retrieving near surface moisture and temperatures. The feasibility of retrieving cloud base temperature and height is an essential component that is required for retrieving CCN from satellites by using convective clouds as natural CCN chambers.