87th AMS Annual Meeting

Wednesday, 17 January 2007
Mapping the climatology of 0-1 hour convective initiation across the Southeastern U. S. and Central America
Exhibit Hall C (Henry B. Gonzalez Convention Center)
John R. Mecikalski, University of Alabama in Huntsville, Huntsville, AL; and L. Gambill, K. M. Bedka, and H. Searcy
Archived 1 km resolution GOES infrared fields used to produce 0-1 hour "nowcasts" of convective initiation (the first occurrence of a 35 dBZ echo from a cumuliform cloud) are analyzed on mesoscale to regional scales. These infrared fields include such quantities as cloud-top cooling rates for moving cumulus, and an additional seven infrared fields that describe cloud growth (i.e. updrafts) towards the development of cumulonimbus clouds. These satellite data sets, produced each half-hour during daytime, have been collected since early 2005. The goal of this research is an eventual long-term (>10 year) analysis of initial convective precipitation development using historical GOES data.

Once performed over the southeastern U.S., further analysis will occur over Central America as we test the following hypotheses: (a) There exists a trend in rainy season (May-October) longevity as a function of land-use and local climate change over the past 30 years in Central America (Mesoamerica), and subsequently the meteorological conditions within tropical ecosystems across have been altered, as a partial result of human presence and activity. (b) A statistical relationship exists, and can be formulated, between land-use and satellite-observed low (cumulus) cloud properties (i.e. frequency, depth, cloud base height) and precipitation on small spatial scales (1-10 km), from the mesoscale down to the kilometer/cumulus scale in the vicinity of tropical and montane cloud forests (e.g., as a function of wind regime, distance from coast, forest fragmentation).

This study squarely address how mesoscale weather phenomena, in this case clouds and precipitation, may be altered from its "original," pre-industrial state climate by such things as land-use change and perhaps large-scale climate change. The presentation will provide the methodology on how the composite fields are developed, and how confident we are with the information they provide.

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