P2.43 GOES Winter Precipitation efficiency algorithm

Wednesday, 27 June 2007
Summit C (The Yarrow Resort Hotel and Conference Center)
Robert M. Rabin, NOAA/NSSL, Norman, OK; and J. Hanna

Recent studies have shown the importance of snow microphysics for heavy snowfall. Specifically, snow production and accumulation appears to be highly efficient when a maximum in saturated vertical ascent (level of non-divergence) is collocated within a narrow temperature range (centered at -15ºC). This temperature range is favorable for efficient snow production as a result of the preferential growth of ice crystals by deposition. In addition the dominant crystal type formed in this temperature range is dendrites which have been shown to be conducive for high snow to liquid ratios.

To highlight areas conducive for this highly efficient snowfall a GOES Winter Precipitation Efficiency Algorithm was developed by the lead author. The GOES Winter Precipitation Efficiency Algorithm uses cloud products derived from Geostationary Operational Environmental Satellite (GOES) Imager radiances to create an analysis of the height of the pressure level at -15ºC. Further refinement of the analysis is conducted by including vertical velocity output from the Rapid Update Cycle (RUC) to highlight areas where the -15ºC pressure level is collocated with moderate lift (defined in the algorithm as -10µb/sec).

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