Vertical and Horizontal Gradients in Aerosol Black Carbon and Its Mass Fraction to Composite Aerosols over the East Coast of Peninsular India from Aircraft Measurements

During the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) experiment of ISRO-GBP, altitude profiles of mass concentrations of aerosol black carbon (M-B) and total (composite) aerosols (M-T) in the lower troposphere were made onboard an aircraft from an urban location, Chennai (13.04 degrees N, 80.17 degrees E). The profiling was carried out up to 3 km (AGL) in eight levels to obtain higher resolution in altitude. Besides, to explore the horizontal gradient in the vertical profiles, measurements were made at two levels [500 m (within ABL) and 1500 m (above ABL)] from similar to 10 degrees N to 16 degrees N and similar to 80 degrees E to 84 degrees E. The profiles showed a significant vertical extent of aerosols over coastal and offshore regions around Chennai with BC concentrations (similar to 2 mu g m(-3)) and its contribution to composite aerosols remaining at the same level (between 8 to 10% for F-BC) as at the surface. Even though the values are not unusually high as far as an urban location is concerned, but their constancy throughout the vertical column will have important implications to climate impact of aerosols.