The Study Of Aerosol Microphysical And Optical Parameters Total Columnar Ozone And Water Vapor Content Derived From Sunphotometer

The spectral aerosol optical depth measurements are estimated over Addis Ababarn(09.033N , 38.7E) at 2445m a.m.s.l. from the measurements of direct solar irradiancernat different wavelengthes in the range between 305.3-1020nm using a hand heldrn5-channel Microtops II sunphotometer (Solar light co. USA) for the first time. Resultsrnshow wavelength dependence of aerosol optical depth (AOD) which graduallyrndecreases with increasing wavelength, having mean value of 0.209 (±0.0625) at 1020rnnm optical channel. The °Angstrom exponent and turbidity were found to berninversely related with a good anticorrelation (R = −0.807) and the °Angstrom exponentrn was observed to be small in the range from (0.204) to (0.993) with a meanrnvalue of (0.627) indicates the presence of coarse mode particles over the site. Temporalrnvariation of both AOD and retrieved columnar size distribution (ASD) showrnminimum value during the noon time. Large value with large variability in AODrnand ASD are observed in April, 2009 as compered to March and May, 2009. This isrnattributed to the long range transported aerosols from different source. A good positiverncorrelation between aerosol optical depth (AOD) and precipitable water contentrn(PWC) were observed during the measurements of March and may which attributedrnto the presence of hygroscopic aerosols over the site. The day-to-day variations inrntotal columnar ozone (TCO) were found to be in fair agreement (10−14%) deviationrnfrom TOMS satellite data for all the experimental days, having mean observed valuernof 294.45 (±6.61) DU over the station.rnKeywords: Aerosols; Aerosol optical depth; Aerosol size distribution; °Angstrm parameters;rntotal columnar ozone; and precipitable water content

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