Multi year changes of Aerosol Optical Depth in the monsoon region of the Indian Ocean since 1986 as seen in the AVHRR and TOMS data

摘要

Aerosol Optical Depth (AOD) data based on AVHRR and TOMSwas analyzed to find out the changes in the Indian Ocean from 1981 to 2004.Four regions covering Indian Ocean north of 10° S were studied indetail. The results strongly suggest that the mean value of AOD in theseregions decreased from 1986–1990 to 1995–1999. The Arabian Sea and Bay ofBengal show increase thereafter whereas in the equatorial part it decreasedfurther, during 2000–2004. The drop in AOD from the first to second periodis evident in AVHRR and TOMS in the case of the Arabian Sea (North WestIndian Ocean). The decrease in this case is prominent in summer. Theseresults in general agree with the recently reported global decrease in AOD,"global brightening" and also the reversal of trend in some of theanthropogenic emissions.