Chemical Composition of the Asian Tropopause Aerosol Layer

Tuesday, 20 March 2018
Iriarte (Hotel Botanico)
Hazel Vernier1, Neeraj Rastogi2, Fairlie T Duncan3, Jean-Paul Vernier3, Amit K Pandit4, Anil Patel5, Sunil Kumar6, M Venkat Ratnam7 and Harish Gadhavi8, (1)Virginia Institute of Marine Science, CBH, Gloucester point, VA, United States, (2)Physical Research Laboratory, Chemistry, Ahmedabad, GA, India, (3)NASA Langley Research Center, Hampton, VA, United States, (4)Physical Research Laboratory, Physics, Ahmedabad, India, (5)Physical Research Laboratory, Chmistry, Ahmedabad, India, (6)Tata Institute of Fundamental Research, Hyderabad, India, (7)National Atmospheric Research Laboratory, Tirupati, India, (8)Physical Research Laboratory, Ahmedabad, India
Abstract:
Over the last decades pollution in Asia has increased drastically following economic growth with subsequent impacts on air quality and the monsoons. It’s now well established that the Asian summer monsoon contributes to the formation of the Asian Tropopause Aerosol Layer (ATAL). While the optical and physical properties of the ATAL have been inferred from satellite observations and balloon-borne measurements for several years, the chemical composition of the ATAL remains uncertain. We present here the first Ion Chromatography analysis of aerosols collected as a part of the Balloon measurement campaign of Asian Tropopause Aerosol Layer (BATAL) during a deployment at the balloon facility of the Tata Institute of Fundamental Research, Hyderabad, India in August 2017. We used filters on a 4-stage impactor connected to a pump and a mass flow controller to collect aerosols during two balloon flights dedicated to float for several hours near the tropopause. Water soluble ions like SO42−, NO3-, NO2-, Cl-, Na, K, Ca, & Mg2+ were extracted using ultra-pure mili-Q water in pre-cleaned polypropylene vials using ultrasonic technique. Chemical analysis of water soluble ions was carried out using Dual Channel Ion Chromatograph (DIONEX ICS 5000) for parallel measurements of cations and anions. Ions were quantified using linear calibration curves obtained using standard solution of corresponding ions. We report the dominant presence of NO3-, and NO2- aerosols during the 2 zero pressure flights held in Hyderabad. The origin of air masses sampled during the balloon flights will be discussed using back trajectory and GEOS-Chem simulations together with satellite observations from the Cloud-Aerosol Lidar and InfraRed Pathfinder Satellite Observations (CALIPSO) and the newly installed Stratospheric Aerosol and Gas Experiment III on the ISS.
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