Extended Abstract (444K)6A.4
Reflective storm tops: a satellite method for inferring thunderstorm top microphysical structure
Daniel T. Lindsey, NOAA/NESDIS, Fort Collins, CO; and L. Grasso
The utility of GOES channel 1 (visible) and channel 4 (longwave infrared) imagery has long been recognized in terms of thunderstorm nowcasting. However, few studies have addressed the application of the shortwave infrared channel 2 (3.9 μm) to storm top analysis. During the daytime, channel 2 has an emitted thermal component, but for cold thunderstorm tops, a reflected solar component makes a significant contribution to the total radiance. The amount of shortwave reflectance depends on the microphysical structure at cloud top; smaller ice crystals tend to reflect more incoming radiation. We therefore can make inferences about cloud-top microphysical structure based on channel 2 albedo values.
Though still under investigation, ice crystal size at cloud top may be related to updraft strength, moisture properties of the environment, and potentially other relevant parameters. A climatological study of “reflective” storm tops was performed, and a distinct maximum was found downwind of mountain ranges in the continental US, especially in the high plains of Colorado, Wyoming, and New Mexico. Additionally, if a storm top meets certain minimum reflectivity properties, the storm is five times more likely to produce severe weather (based on 3 months of data).
This presentation will introduce the concept of reflective storm tops, discuss the climatology of reflective ice clouds, and provide modeling results which link shortwave albedo to cloud-top microphysics. Potential applications to thunderstorm nowcasting will also be discussed.
Supplementary URL: http://rammb.cira.colostate.edu/research/severe/reflective.asp
Session 6A, Hazardous Weather Tools–Satellite, Radar and Mesoscale Networks of Observing Sensors, including Hydrology
Tuesday, 2 August 2005, 8:00 AM-8:30 AM, Ambassador Ballroom
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