Analysis of long-­‐term precipitation pattern over Antarctica derived from satellite-­‐borne radar

• Main Authors: Milani, L., D. Casella, S. Dietrich, G. Panegrossi, M. Petracca, P. Sanò, PORCU', FEDERICO
• Other Authors: F. Porcù
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: antarctica; remote sensing; snowfall; climatology; Antarctic; The Antarctic; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/11585/515926; https://doi.org/10.5194/tcd-9-141-2015

Mass accumulation is a key geophysical parameter in understanding the Antarctic climate and its role in the global system. The local mass variation is driven by a number of different mechanisms: the deposition of snow and ice crystals on the surface from the atmosphere is generally modified by strong surface winds and variations in temperature and humidity at the ground, making it difficult to measure directly the accumulation by a sparse network of ground based instruments. Moreover, the low cloud total water/ice content and the varying radiative properties of the ground pose problems in the retrieval of precipitation from passive space-borne sensors at all frequencies. Finally, numerical models, despite their high spatial and temporal resolution, show discordant results and are difficult to be validated using ground-based measurements. A significant improvement in the knowledge of the atmospheric contribution to the mass balance over Antarctica is possible by using active space-borne instruments, such as the Cloud Profiling Radar (CPR) on board the low earth orbit CloudSat satellite, launched in 2006 and still operating. The radar measures the vertical profile of reflectivity at 94 GHz (sensitive to small ice particles) providing narrow vertical crosssections of clouds along the satellite track. The aim of this work is to show that, after accounting for the characteristics of precipitation and the eect of surface on reflectivity in Antarctica, the CPR can retrieve snowfall rates on a single event temporal scale. Furthermore, the CPR, despite its limited temporal and spatial sampling capabilities, also effectively observes the annual snowfall cycle in this region. Two years of CloudSat data over Antarctica are analyzed and converted in water equivalent snowfall rate. Two different approaches for precipitation estimates are considered in this work. The results are analyzed in terms of annual and monthly averages, as well as in terms of instantaneous values. The derived snowfall maps are compared with ERA-Interim ...