Boris Barja¹, Juan Carlos Antuña¹

¹Camagüey Lidar Station, Meteorological Center of Camagüey. INSMET. Cuba

Cirrus clouds radiative forcing effects on shortwave radiation have been studied combining lidar measurements with a state of the art radiative transfer code. For this purpose 132 profiles of backscatter lidar observations at 532 nm were used. The selected profiles were collected during 1993 – 1998 period. The radiative transfer code was adapted to the local conditions at Camagüey, Cuba, using water vapor and temperature profiles as well as locally measured surface albedo from the site. Runs were conducted both under the presence of cirrus clouds and in clear sky conditions. The calculated shortwave broadband cloud radiative forcing values vary according to the different optical depths of cirrus. A close correlation between the cirrus radiative forcing and optical depth was found at the top of the atmosphere and surface when broadband is analyzed. This close correlation was found also in different intervals of wavelength in the solar spectrum (near infrared, visible, and ultraviolet). The major effect of cirrus clouds on the solar radiation is in the near infrared wavelengths. Limitations of the current lidar dataset are discussed.