Multiwavelength solar radiometer network and features of aerosol spectral optical depth at Trivandrum

Five multiwavelength solar radiometers have been developed and deployed at Trivandrum, Mysore, Waltair, Jodhpur and New Delhi establishing a network during Indian Middle Atmosphere Program. The instruments measure atmospheric columnar optical depth at nine wavelengths in the visible and near infrared enabling studies on physical features of aerosols and integrated content of atmospheric water vapor. Using this instrument, measurements of aerosol optical depth and atmospheric water vapor have been made at Trivandrum since November 1985. The monthly, seasonal and spectral variations of aerosol optical depth are studied and their implications are discussed in the light of earlier findings