HR: 14:55h
AN: A33F-06    [Abstracts]
TI: Atmospheric Heating by Saharan Dust and Its Implication on the Temperature Profiles over the Tropical Cyclone Main Development Region
AU: * Wong, S
EM: swong@neo.tamu.edu
AF: Dept. of Atmospheric Sciences Texas A&M University, TAMU 3150, College Station, TX 77843-3150, United States
AU: Dessler, A E
EM: adessler@tamu.edu
AF: Dept. of Atmospheric Sciences Texas A&M University, TAMU 3150, College Station, TX 77843-3150, United States
AU: Mahowald, N
EM: nmm63@cornell.edu
AF: Cornell University, 2140 Snee Hall, Cornell University, Ithaca, NY 14850, United States
AU: Yang, P
EM: pyang@airel.met.tamu.edu
AF: Dept. of Atmospheric Sciences Texas A&M University, TAMU 3150, College Station, TX 77843-3150, United States
AU: Feng, Q
EM: fengqian@ariel.met.tamu.edu
AF: Dept. of Atmospheric Sciences Texas A&M University, TAMU 3150, College Station, TX 77843-3150, United States
AB: We have investigated anomalies in atmospheric temperature profiles that are associated with Saharan dust over the tropical cyclone main development region (10°-20°N, 20°-30°W), using temperature data from Atmospheric Infrared Sounder (AIRS) and aerosol data from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that Saharan dust is associated with a vertical temperature structure that has a warm anomaly lying above the marine boundary layer (~850 hPa) and a cold anomaly throughout the middle troposphere (~350-600 hPa). We then estimate dynamical and dust radiative heating of the atmospheric column. The dynamical heating is estimated using wind and temperature data from NCEP reanalysis, while the dust radiative heating is computed using the NASA/GSFC CLIRAD radiative transfer model for both shortwave and longwave. Dust particle size distributions and vertical concentration profiles for use in the radiative transfer calculations are prescribed according to the simulation of the MATCH dust transport model. The warm anomaly in the lower tropsphere can be explained by the dynamical and dust radiative heating. For air columns with aerosol optical thickness greater than one, the dust heating rate is at least 20% of the dynamical heating rate in the lower troposphere. The cold anomaly in the middle troposphere cannot be explained by dynamical or radiative heating. Suppression of deep convection probably plays an essential role in cooling the middle troposphere over the dust layer by reduction of latent heat release. We will also investigate the sensitivity of dust radiative heating rate using assumed particle shapes for dust.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0350 Pressure, density, and temperature
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting