Helene Chepfer is collaborating with researchers of CIRES Environmental, Observations, Modeling and Forecasting division to understand the role of clouds and precipitations on the polar climate. In particular, they are using the observations collected by the active remote sensing instruments (CALIPSO lidar and CloudSat radar) part of the A-train, to understand how clouds and precipitations interact with the ice sheet over Greenland. Clouds and the atmospheric state play fundamental roles in the cryospheric mass budget of the Greenland ice sheet both as a source, via precipitation, and potential sink, via modulation of the surface energy budget. Understanding present and future manifestations of change to the Greenland ice sheet requires an explicit understanding of regional atmospheric processes, including how the atmospheric processes interact with the ice sheet and how they might be modulated as their environment changes. The observations collected by CALIPSO and CloudSat since 2006, complete the information collected over Greenland ground base sites, by providing, for the first time, an almost-decadal view of the detailed vertical distribution of clouds and precipitations over the entire Greenland. Those observations are used by Helene Chepfer and CIRES researchers to understand the cloud and precipitation-related processes over Greenland, and to constrain the description of polar clouds in climate models, a necessary step toward more reliable predictions of future polar climate evolution.