A model for the natural and anthropogenic aerosols over the tropical Indian Ocean derived from Indian Ocean Experiment data

摘要: The physical, chemical and radiative properties of aerosols are investigated over the tropical Indian Ocean during first field phase (FFP) international Experiment. FFP was conducted February 20 to March 31, 1998. results shown here from Kaashidhoo Climate Observatory (KCO), a new surface observatory established on tiny island (4.965°N, 73.466°E) in Republic Maldives. From simultaneous measurements aerosol chemical, vertical structure lidar, we have developed an model which, conjunction with Monte Carlo transfer model, successfully explains (within few percent) observed solar fluxes at top atmosphere. This agreement demonstrates fundamental importance measuring physical for modeling fluxes. KCO, northeast monsoon period considered here, is downwind subcontinent undergoes variations visible optical depth τν ∼0.1 0.4, monthly mean ∼0.2. Lidar data suggest that confined largely 3 kms. Sulfate ammonium contribute ∼29% τν; sea-salt nitrate contributes ∼17%; mineral dust ∼15%; inferred soot, organics, fly ash 11%, 20%, 8% respectively. We estimate anthropogenic sources may as much 65% τν. consider both externally internally mixed very little difference between two computed forcing. scattering coefficients upper range those reported other oceanic regions, single-scattering albedos low 0.9, Angstrom wavelength exponents ∼1.2 indicate abundance submicron aerosols. In summary, confirm large impact sources. global (for overhead Sun) decrease by 50 80 W m−2 owing presence aerosols, atmosphere increase 15 m−2, thus indicating having Ocean.