Vol. 17, issue 05-06, article # 9

Abstract:

We present some results of inverting the spectral data on the aerosol optical depth (AOD) measured over different regions of the Atlantic. It is shown that the remoteness of these regions from numerous secondary continental sources generating the aerosol is an important factor determining the features of the optical and microphysical properties of the atmospheric aerosol over the ocean. It has been found that in the mid-latitudes the volume content of the accumulative aerosol fraction V_ac(r < 0.4 mm) decreases by several times (from 3 x 10³ to 3 x 10² mm³ x cm^-2) with the distance from the European continent, while that of the medium fraction V_md (0.4 < r < 1.2 mm) is stable and equal, on the average, to 1,4 x 10³ mm3 x cm^-2. In the tropics, the effect of intake of the continental aerosol manifests itself all over the size range analyzed. Just this effect governs the formation of the aerosol size spectrum. The results of interpretation of the mean spectral AOD have shown that V_md halves (from 2 x 10³ to 6,0 x 10³ mm3 x cm^-2) when going on from the Sea of Darkness into the trade-wind zone, which confirms that the effect of the dust aerosol from the Sahara Desert weakens with the distance from the African continent. Despite the predominantly zonal distribution of the climate and meteorological characteristics of the atmosphere, the major factors determining the regional features of AOD over the ocean are the processes regulating the penetration of the continental air masses enriched with aerosol into one or another region.