Towards a better low-level cloud retrieval in the Arctic Ocean

Arctic low-level clouds, which are often long-lived and liquid-containing mixed-phase clouds, have a large impact on the surface energy budget, especially in the wintertime when the solar radiation is weak or absent, the atmosphere is very dry, and strong temperature inversion persists. However, observations for these low clouds remain sparse due to the difficulty of obtaining in-situ data in the harsh environment and the inherent shortcomings of active remote sensing measurements near the ground level. One of the goals of the next observing system—The Aerosol, Cloud, Convection, and Precipitation (ACCP)—is to advance our ability to detect and probe the properties of low-level clouds and precipitations. In this study, we are using a 3-D high-resolution cloud-resolving model (System for Atmospheric Modeling; SAM), as well as forward models, to assess the existing spaceborne radar system (CloudSat CPR) in terms of retrieving the microphysical and radiative properties of cold low-level clouds. In addition, we will simulate the capabilities of the next generation observing system (multifrequency radar system) in the Arctic. Specifically, we conduct SAM simulations with a two-moment microphysical scheme for a range of conditions over the wintertime Arctic, which will be further used as input for the forward model to simulate radar reflectivity, brightness temperature, and path integrated attenuation over both ocean water surface and sea ice/snow surface. All those forwarded quantities are very useful constraints that will help to validate the retrieval algorithms and examine the feasibility of the next generation of radars.