BATAL-2014: Balloon characterization of the Asian Tropopause Aerosol Layer

BATAL team

Satellite observations have recently shown that the Summer Asian Monsoon leads to the formation of an aerosol layer in the upper troposphere extending from the Eastern Mediterranean Sea to Western China. Firstly discovered by analyzing data from the CALIPSO space-borne lidar and recently confirmed by past SAGE-II limb observations, this Asian Tropopause Aerosol Layer (ATAL) seems to be the main source of aerosols in the tropical upper troposphere during volcanic quiescent periods. Analysis of long-term satellite observations suggests the emergence of this feature since the beginning 2000's, representing a new source of radiative forcing for the Asian Region which could potentially alters the earth energy balance.

A balloon field campaign was mounted to characterize the aerosol optical properties and size distribution of the Asian Tropopause Aerosol Layer (ATAL). The objective of this mission was to better understand the role of convection over the Indian sub-continent in the formation of the ATAL. A 10-day field experiment between 15-27 August 2014, based in Gadanki (13.4°N,71.2°E, India) at the National Atmospheric Research Laboratory (NARL), has deployed 7 flights of a two-wavelength aerosol backscatter sonde and one Optical Particle Counter configured for light weather balloons.

Radiosonde passing Lidar beam

The balloon campaign was supported by intensive ground-based lidar and radar measurements. In addition, a similar balloon field campaign took place from Kunming (China). Altogether, those deployments represent the most significant effort to date in order to better understand the nature, origin and formation of the ATAL throughout Asia.