His research interests include: remote sensing of cloud and precipitation properties, numerical modeling of cloud systems, and the use of Bayesian algorithms in the development of new data assimilation methodologies and remote sensing techniques. He has experience as a user and developer of the NASA Goddard Earth Observing System (GEOS) model, the NASA Goddard Cumulus Ensemble (GCE) model, the NCAR Cloud Model (CM1), and the Weather Research and Forecasting (WRF) model.

Dr. Posselt is currently a member of the science teams for the Cyclone Global Navigation Satellite System (CYGNSS), Aerosols Clouds Ecosystems (ACE), and CloudSat missions.