Synoptic patterns associated with dusty and non-dusty seasons in the Sahara

The difference in the synoptic situation between years with a large amount of dust and years with a relatively small amount, in the Sahara, have been examined for the period 1979–1992. A comparison has been made separately for each season. For every month the dustiest and least dustiest years, determined by the deviation from the mean, were chosen and the average of the three months of each classical season for these years was examined. The examination was made for wind flow, geopotential height and temperature at the 700 hPa level, and appropriate maps of these variables have been prepared. The data used were the daily aerosol index (AI) from the TOMS satellite-borne instrument and daily NCEP/NCAR reanalysis data for the years 1979–1992.