92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 11:30 AM
Enhancing Understanding of Convective Cloud Processes Using Satellite-Derived Fields for 0–1 Hour Convective Initiation Nowcasting
Room 245 (New Orleans Convention Center )
John R. Mecikalski, Univ. of Alabama in Huntsville, Huntsville, AL; and C. P. Jewett, P. Watts, and M. Koenig

This presentation highlights the recent improvements in the 0-1 h forecasting (“nowcasting”) of the initiation of thunderstorms, with the main emphasis being on how infrared and derived fields from the SEVIRI instrument aboard Meteosat Second Generation (MSG) can be used, and how environmental information can be accounted for toward fine-tuning the use of infrared “interest fields.” The goal for accurate high-temporal convective initiation (CI) forecasting has resulted in ways to broaden our understanding of GOES and MSG datasets that observe growing cumulus clouds. Convective initiation is defined as a transition from below to above 35 dBZ echoes as observed by radar near the –10 C level.

This presentation highlights and overviews several areas of new research in CI nowcasting and convective cloud diagnosis: (1) Optimal Cloud Analysis (OCA) retrievals from MSG of cloud-top phase, particle effective radius, and optical depth are evaluated in conjunction with SEVIRI's CI interest fields to help diagnose in-cloud processes (updraft strength, glaciation, updraft width), including growth rates and in-cloud microphysical structures of the convective clouds. (2) Uses of thermal sharpening as a means of increasing the signal of growing cumulus clouds in single pixel, cloud objects and OCA fields, toward enhancing understanding of physical processes of convection and nowcasting CI. (3) Developing ways to identify CI that occurs beneath cirrus clouds. And, (4) evaluation of methods to use infrared satellite observations to adjust thresholds used to evaluate pixels and/or objects for the occurrence of CI within the 1-hour timeframe. For this effort, several datasets are used: In Europe, MSG data for 123 CI events (plus ~100 null events) during the COPS 2007 field experiment over southern Germany and northeastern France, 44 CI events on 25 May 2009, and additional CI events on 15 August 2010, are analyzed. Over the US, CI events during two week-long periods in spring 2011 are evaluated, in addition to a test database of ~2500 CI events (including null forecasts), are analyzed. Use of larger validation datasets allows for accuracy assessments, which will also be reported on.

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