Understanding the Distribution of VSLS and Their Interhemispheric Transport Based on Global Model Simulation and Measurement Data

BEERHOZ ROOZITALAB; HORNBROOK, REBECCA S.; EMMONS, LOUISA K.; DOUGLAS E. KINNISON; WANG, SIYUAN; ALFONSO SAIZ-LOPEZ; LI, QINYI; RAFAEL PEDRO FERNÁNDEZ; MONTZKA, STEPHEN A.; BLAKE, DONALD R.; ATLAS, ELLIOT L.; APEL, ERIC C.

Conferencia; https://agu.confex.com/agu/fm22/meetingapp.cgi/Paper/1159532; 2021

Halogenated very short-lived substances (VSLS) undergo photolysis and reactions with hydroxyl radicals, releasing halogen species such as chlorine and bromine both in the troposphere and lower stratosphere. Consequently, these halogens impact the oxidation capacity and radiation balance, deplete atmospheric ozone, and affect the lifetime of methane. In this work, we use observational datasets and model simulations to investigate the distribution of VSLS, their interhemispheric transport, and impacts on atmospheric chemistry. In particular, we analyze the data from NASA Atmospheric Tomography (ATom) and NSF O2/N2 Ratio and CO2 Airborne Southern Ocean (ORCAS) field campaigns, which measured VSLS over the Pacific and Atlantic, and Southern Oceans, using different instruments. Our preliminary results show higher concentrations for chlorinated VSLS (i.e. CHCl3, CH2Cl2, and C2Cl4) over the Northern Hemisphere compared with the Southern Hemisphere. On the contrary, results do not show any significant hemispheric contrast for brominated VSLS (e.g. CHBr3 and CH2Br2). Furthermore, the results show differences in vertical gradients for different VSLS and regions. We use the Community Atmosphere Model with Chemistry (CAM-chem), a component of the NCAR Community Earth System Model (CESM) to understand the vertical and horizontal transport of VSLS on the global scale. For VSLS emissions, we use the available emission inventories in the literature for anthropogenic sources and climatology data for natural sources. This work will also identify the shortcomings of the current model configurations in terms of both natural sources’ emission magnitudes and gas-phase chemical mechanisms.