Cloud Properties in the Winter Arctic from MODIS Data

Arctic clouds are important components of the polar climate system. Cloud observation from satellites is difficult during the Arctic winter because visible channels are useless and clouds are frequently trapped below a surface-based temperature inversion, which results in little thermal contrast between cloud-tops and the surface.

Temperature and humidity profiles from rawinsondes at the Barrow ARM (Atmospheric Radiation Measurement) program site are used in a forward radiative transfer model to simulate relationships among the brightness temperature at the top of atmosphere in several infrared bands for varying cloud droplet effective radius, optical depth, and phase. These relationships are useful guides for interpreting brightness temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Anticipated accomplishments include estimates of cloud mask, cloud-top phase, optical depth, and top height from MODIS over snow and ice during the Arctic winter. Validation data, such as surface-based millimeter cloud radar and micropulse lidar, also come from the Barrow ARM site.