AEROSOL OPTICAL DEPTHS IN A SEMIARID REGION

To monitor changes in surface conditions from space requires informati on on the state of the atmosphere to correct for atmospheric effects i n the remotely sensed signal. The least observed and most variable atm ospheric parameters are aerosols. Of particular interest are changes o f surface conditions in areas where desert encroachment is of concern An effort was initiated at one of such locations to monitor atmospheri c conditions from the ground and surface conditions from space. In thi s paper we present results only on the ground observations of the aero sol optical depths, in particular their annual and diurnal variations, in the context of prevailing synoptic conditions.