Nitric acid particles in cold thick ice clouds observed at global scale: Link with lightning, temperature, and upper tropospheric water vapor
نویسندگان
چکیده
Signatures of nitric acid particles (NAP) in cold thick ice clouds have been derived from satellite observations. Most NAP are detected in the Tropics (9 to 20% of clouds with T< 202.5 K). Higher occurrences were found in the rare mid-latitudes very cold clouds. NAP occurrence increases as cloud temperature decreases and NAP are more numerous in January than July. Comparisons of NAP and lightning distributions show that lightning is the main source of the NOx, which forms NAP in cold clouds. Qualitative comparisons of NAP with upper tropospheric humidity distributions suggest that NAP play a role in the dehydration of the upper troposphere when the tropopause is colder than 195K.
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