HR: 14:00h
AN: A43C-02    [Abstracts]
TI: African aerosol and interannual variability of precipitation in the Atlantic ITCZ
AU: * Huang, J
EM: jhuang@rsmas.miami.edu
AF: University of Miami, 4600 Rickenbacker Causeway Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, United States
AU: Zhang, C
EM: czhang@rsmas.miami.edu
AF: University of Miami, 4600 Rickenbacker Causeway Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, United States
AU: Prospero, J
EM: jprospero@rsmas.miami.edu
AF: University of Miami, 4600 Rickenbacker Causeway Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, United States
AB: The interannual variability of precipitation in the Atlantic marine ITCZ (AMI) is affected by many factors. Possible aerosol effects have, however, not been thoroughly investigated, although huge quantities of African aerosol are transported over tropical Atlantic each year. Using satellite observations of aerosol (TOMS) and precipitation (GPCP) over the period 1979-2000, this study elucidates possible large-scale, interannual relationships between the absorbing aerosol (primarily mineral dust and carbonaceous aerosol) and precipitation in the AMI. For each calendar month, a composite of precipitation difference between years of anomalously high and low aerosol was made. It is found that possible influence of aerosol on precipitation in the AMI have a strong seasonality. Averaged over the tropical Atlantic, the aerosol-related variability in precipitation explains 5-25% of the variance of precipitation after effects from ENSO, zonal and meridional modes of tropical Atlantic SST and North Atlantic Oscillation (NAO) are removed. This fractional variance related to aerosol can be as high as 40-50% in some regions of the AMI in particular months (such as January and February). From the anomalously low to anomalously high aerosol years, the precipitation is generally suppressed in boreal autumn and winter. A northward shift of the AMI is observed in winter and a southward shift in spring. Based on a Monte Carlo simulation and the Kolmogorov-Smirnov test, the precipitation changes related to aerosol are significantly different from those due to random sampling at 95% confidence level. Aerosol therefore might play an important role in modifying spatial distribution of precipitation in the AMI in addition to known climatic factors (e.g., ENSO, tropical Atlantic SST modes, NAO). Further studies are needed to explore whether the precipitation changes related to aerosol are indeed caused by aerosol effects or by other associated factors, such as dry air and large- scale circulation.
UR: http:metofis.rsmas.miami.edu/~jhuang/ami/index.htm
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3311 Clouds and aerosols
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3354 Precipitation (1854)
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly