Publication Date:
2016-05-28
Description:
We have developed semi-independent methods for determining CH 2 O scavenging efficiencies (SEs) during strong mid-latitude convection over the western, south-central Great Plains, and southeastern regions of the United States during the 2012 Deep Convective Clouds and Chemistry (DC3) Study. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) was employed to simulate one DC3 case to provide an independent approach of estimating SEs and the opportunity to study CH 2 O retention in ice when liquid drops freeze. Measurements of CH 2 O in storm inflow and outflow were acquired onboard the NASA DC-8 and the NSF/NCAR Gulfstream V (GV) aircraft employing cross-calibrated infrared absorption spectrometers. This study also relied heavily on the non-reactive tracers i/n-butane and i/n-pentane measured on both aircraft in determining lateral entrainment rates during convection as well as their ratios to ensure that inflow and outflow airmasses did not have different origins. Of the 5 storm cases studied, the various tracer measurements showed that the inflow and outflow from 4 storms were coherently related. The combined average of the various approaches from these storms yield remarkably consistent CH 2 O scavenging efficiency percentages of: 54% ± 3% for May 29; 54% ± 6% for June 6; 58% ± 13% for June 11; and 41 ± 4% for June 22. The WRF-Chem SE result of 53% for May 29 was achieved only when assuming complete CH 2 O degassing from ice. Further analysis indicated that proper selection of corresponding inflow and outflow time segments is more important than the particular mixing model employed.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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