Science

The Balloon measurement campaigns of the Asian Tropopause Aerosol Layer (BATAL) is a series of field missions to study the transport of pollution in the Upper Troposphere and Lower during the Summer Asian Monsoon. The missions involve scientists, engineers and students from the United States, India, Saudi-Arabia, France and Switzerland and eleven different institutes including NASA’s Langley Research Center. The key objectives are to provide in situ balloon-borne observations to understand how Asian pollution can affect climate and stratospheric chemistry during the Summer Asian Monsoon, and to validate CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) and SAGE/ISS (Stratospheric Aerosol and Gas Experiment III on the International Space Station) satellite observations.

Every summer, the South East Asian Monsoon supplies water to more than 1.5 billion people for their basic needs. Over the past few decades, countries in Asia have seen their economies to expand at an unprecedented pace, leading to release enormous amounts of pollution in the atmosphere with consequences on human health and climate. Scientists believe that the monsoon contributes to the spread of pollution from regional to global scale via vertical and horizontal transport pathways provided by the monsoon. Indeed, large and powerful cumulonimbus clouds can uplift pollution up to the upper troposphere and lower stratosphere from which it can circulate at a hemispheric scales. As evidence for this transport, satellite observations have observed carbon monoxide and tiny particles between 13-18 km from a large area between the Eastern Mediterranean Sea to Western China during the monsoon. Numerical models support the idea that pollution in South East Asia is responsible for the formation of aerosol layers in the lower stratosphere so called the Asian Tropopause Aerosol Layer (ATAL).

The ATAL was first discovered through high-resolution profiles of aerosol backscatter measured by CALIPSO and confirmed by the Stratospheric Aerosol and Gas Experiment (SAGE II). Trends in particle concentration has likely increased by a factor of 2 to 3 over the past 16 years following pollution growth on the ground.

However, in situ measurements have lacked validation of satellite observations and provided additional information on the physical and chemical properties of the ATAL. Thus, since 2014, we have mounted a balloon program to make in situ measurements of aerosol, ozone, and water vapor in the upper troposphere and lower stratosphere in Asia to study the nature, origin and formation of the ATAL.

This collaborative effort between NASA LaRC, Science Systems Applications Inc., and partners from the University of Wyoming, the National Atmosphere Research Laboratory (NARL), Gadanki, India, the Tata Institute of Fundamental Research, (TIFR) Hyderabad, Baranas Hindu University, Varanasi, and the King Abdullah University of Science and Technology (KAUST), Saudi Arabia, has been key to a successful campaign.