Overview of the CrIMSS (CrIS/ATMS) retrieval algorithm Xu Liu and Jean-Luc Moncet, AER, Inc AER is the retrieval algorithm developer for the Cross Track Infrared and Microwave Sounder Suite (CrIMSS), which will fly onboard of NPP and NPOESS platforms. The infrared component of the CrIMSS is an interferometer-based Cross-Track Infrared Sounder (CrIS). The microwave component is an Advance Technology Microwave Sounder (ATMS). The radiative transfer forward model uses an innovative parameterization, which models both radiances and weighting functions accurately and efficiently. The inversion algorithm uses a physical retrieval method to retrieve atmospheric and surface properties from both microwave and infrared sensors. Different strategies for dealing with clouds will be discussed. Some results of applying the CrIMSS algorithm to real data will be presented.