Frequency of Occurrence of UV-absorbing Aerosols
The image below shows how often the Nimbus-7/TOMS aerosol index detected the presence of UV-absorbing tropospheric aerosols over each region of the Earth during July, August, and September of 1987 and 1988. The areas in South America and Africa south of the equator indicate smoke produced by biomass burning. A large amount of the smoke from Africa can be seen to collect just off the coast in the Atlantic. In 1988, the smoke from South America is transported to the South Atlantic by the prevailing wind patterns. North of the equator, most of the aerosol is due to dust blowing off of desert regions. The areas in red are areas that almost always contain UV-absorbing aerosol during this time of year. Many of them indicate "source" regions such as the dry lake bed area around Lake Chad (about 15 degrees north latitude, 15 east longitude). Dry lake beds contain fine particulate matter that is easily picked up and transported by blowing wind.
For further information, contact the Principal Investigator for TOMS aerosol research:
Dr. Jay R. Herman Code 613.3 Goddard Space Flight Center Greenbelt, MD 20771 herman@tparty.gsfc.nasa.gov