Thursday, 30 September 2010
ABC Pre-Function (Westin Annapolis)
A suite of products has been developed and evaluated to assess hazards presented by convective downbursts to aircraft in flight derived from the current generation of Geostationary Operational Environmental Satellite (GOES) (8-P). The existing suite of GOES microburst products employs the GOES sounder to calculate risk based on conceptual models of favorable environmental profiles for convective downburst generation. Large output values of the microburst index algorithms indicate that the ambient thermodynamic structure of the troposphere fits the prototypical environment for each respective microburst type (i.e. Wet, Hybrid, Dry, etc.). Accordingly, a diagnostic nowcasting product, the Microburst Windspeed Potential Index (MWPI), is designed to infer attributes of a favorable microburst environment: large CAPE and a convective mixed layer with a steep temperature lapse rate and low relative humidity in the surface layer. These conditions foster intense convective downdrafts due to evaporational cooling as precipitation descends in the sub-cloud layer. More recently, a new application of the brightness temperature difference (BTD) between GOES imager channels 3 and 4 has been developed. It has been found that the BTD between GOES infrared channel 3 (water vapor) and channel 4 (thermal infrared) can highlight regions where severe outflow wind generation (i.e. downbursts, microbursts) is likely due to the channeling of dry mid-tropospheric air into the precipitation core of a deep, moist convective storm. This paper provides an updated assessment of the MWPI and new GOES BTD algorithm, presents case studies demonstrating effective operational use of the microburst products, and presents validation results for the 2010 convective season over United States Great Plains and Atlantic Coast regions.
Supplementary URL: http://arxiv.org/abs/1009.0687
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