2002 Annual

Monday, 14 January 2002: 4:15 PM
Analysis of Gulf Coast Moisture, Aerosols and Weather Regimes
Ronnie Guyton, Jackson State University, Jackson, MS; and P. Croft
An analysis for the identification of moisture and aerosol distributions, sources and sinks, and their variations, is in progress for the Gulf of Mexico coastal region of Louisiana, Mississippi, and Alabama. In an effort to better understand and predict these, moisture and aerosol distributions, sources and sinks, and variations are being characterized through the use of data available from Earth Probe Total Ozone Mapping Spectrometer (EP-TOMS) http://toms.gsfc.nasa.gov/aerosols/aerosols.html. Daily data and images have been collected for the years 1996-2000 of absorbing aerosol. Distributions of data are formatted in an aerosol index value representing UV-absorbing (dust and smoke) and nonabsorbing aerosol. Aerosol Index is a measure of the deviation of I340/I388 from a pure Rayleigh atmosphere. Daily climatological data is being collected, and specific severe weather events have been selected (April 16-17, 1998, April 27-28, 1998, May 4-5, 1999). These are being used for comparative analysis to recognize the tropospheric aerosol and its relation to the synoptic weather pattern, before, during, and after. TOMS measures the relative amount of aerosols-solid or liquid particles suspended in the atmosphere. The TOMS aerosol index (AI) is related to aerosol optical depth, which, in turn, is a measure of how much light airborne particles prevent from passing through a column of atmosphere. The AI does not detect aerosols in the lowest part (about 1 km) of the atmosphere. For aerosol at the most common height of 3 km, an aerosol index of less than 0.1 indicates a crystal clear sky with maximum visibility, whereas a value of 4 indicates the presence of aerosols so dense you would have difficulty seeing the mid-day sun. Aerosols at low altitudes have a lower TOMS aerosol index than an equivalent depth at a higher altitude. Preliminary results have shown high values of absorbing tropospheric aerosol have been present before and during three observed severe weather events, and low values after. For example climatology data for the studied area, recorded unstable weather producing high winds, hail, and heavy rainfall for April 16-17, 1998. During this time period, data showed a high aerosol index value averaging from 2.2 to 3.7. After the severe weather period, April 18-19, 1998, the index value diminished to a low average ranging from 0.0 to 1.2. Knowledge of how tropospheric aerosols and synoptic weather patterns interact will lead to a better understanding, and prediction of their origins, and impacts.

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