AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Temporal Distribution of Short-Lived Climate Forcers, Atmospheric Processes, and Sources at IGP-CARE Site in India for Two Years in-situ Measurements
RAVI KANT PATHAK, Harsh Raj Mishra, Bhilok Chand, Jai Prakash, Mattias Hallquist, Gazala Habib, Johan Boman, Håkan Pleijel, University of Gothenburg, Sweden
Abstract Number: 425 Working Group: Aerosol Chemistry
Abstract Short-lived climate forcers (SLCF) including black carbon (BC), light absorbing organic aerosol (OA): referred as brown carbon (BrC), atmospheric brown clouds (ABC), sulfate and nitrate aerosol; tropospheric ozone (O3), carbon monoxide (CO), and nitrogen oxides (NOX), affect the global climate and human health1-3 and their atmospheric chemistry can also play an important role in Indo Gangetic Plains (IGP) region in India, where 750 million people burn biomass for cooking, heating and agricultural purposes. This study aims to understand the variability of the SLCFs – BC, BrC and O3, by long term in-situ measurements to elucidate the relevant processes involved in rural India. Here, we will present the results from January 2017 to December 2018 measurements at the IGP-CARE (IGP-Centre for Air Research and Education). The IGP-CARE site is a representative rural location (25. 48’ 55.5” N; 79o 55’ 07.5” E) at the middle outflow of IGP. BC and BrC were measured by BC Monitor (BC 1050 series, Met One Instruments, Inc.) on quartz filter tape at two wavelengths (375nm; 880nm). Gaseous species including O3, CO, and NOx along with the meteorological parameters (e.g. WS, WD, RH, T, precipitation etc.) were measured simultaneously using standard commercial instruments. Molecular speciation of organic aerosol species was performed offline using HR-TOF-CIMS (High Resolution Time of Flight Chemical Ionization Mass Spectrometry) and particle collected on the filters.
The results provided insight that temporal distribution the pollution episodes in the winters at the IGP-CARE site were of regional and super-regional scale. A very interesting diurnal variations of BrC/BC ratio was observed. It sharply decreased during day hours and increased in night, which indicates bleaching of BrC. The bleaching of BrC is thought to be affected by temperature, photo- and/or radical chemistry. Chemistry of BrC bleaching is explored and will be presented.