Results from a comparison of HCN measurements and Lagrangian backtrajectory analyses in the Asian Summer Monsoon Anticyclone

Abstract

<p>The StratoClim aircraft field campaign took place from Kathmandu, Nepal, in summer 2017 in<br>order to study the atmospheric composition, chemistry, and dynamics in the Asian Summer<br>Monsoon Anticyclone (ASMA) which is known to transport surface emissions to the mid-latitude<br>lower stratosphere and the stratosphere worldwide. Hydrogen cyanide (HCN) which is primarily<br>emitted from biomass burning and has a UTLS lifetime on the order of 1-2 years is a good tracer for<br>biomass burning import into the lower and free stratosphere.<br>HCN in the ASM Upper Troposphere and Lower Stratosphere (UTLS) was measured in-situ<br>employing the Chemical-Ionization Time-of-Flight Mass Spectrometer FUNMASS on board the<br>high-altitude research aircraft M55-Geophysica. The observed HCN mixing ratios in and above the<br>ASMA exhibit interesting vertical and horizontal signatures around the tropopause as well as in the<br>LS probably resulting from convective activity or air mass origin (AMO). We here compare<br>measured HCN to Lagrangian simulations by the ClaMS and TRACZILLA models which employ<br>two different approaches to represent higher-reaching convective events. The simulations succeed to<br>track some of the observed HCN features back to convective activity or AMO. The quality of the<br>reproduction and further outcomes on the atmospheric relevance will be discussed in the<br>presentation.</p>