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- Title
Assessing the ability to derive rates of polar middle-atmospheric descent using trace gas measurements from remote sensors.
- Authors
Ryan, Niall J.; Kinnison, Douglas E.; Garcia, Rolando R.; Raffalski, Uwe; Palm, Mathias; Notholt, Justus
- Abstract
We investigate the reliability of using trace gas measurements from remote sensing instruments to infer polar atmospheric descent rates during winter. Using output from the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) between 2008 and 2014, tendencies of carbon monoxide (CO) concentrations are used to assess a common assumption of dominant vertical advection of tracers during polar winter. The results show that dynamical processes other than vertical advection are not negligible, meaning that the transport rates derived from trace gas measurements do not represent the mean descent of the atmosphere. The relative importance of vertical advection is lessened during periods directly before and after a sudden stratospheric warming. It was also found that CO chemistry cannot be ignored in the mesosphere due to the night-time layer of OH at approximately 80 km altitude. CO concentration data from the Kiruna Microwave Radiometer and the Microwave Limb Sounder are used in combination with the modelled CO tendencies to estimate errors involved in calculating the mean descent of the atmosphere from remote sensing measurements. The results indicate errors on the same scale as the calculated descent rates, and often a misinterpretation of the direction of air motion. We suggest an alternative definition of the rate calculated using remote sensing measurements: not as the mean descent of the atmosphere, but as an effective rate of vertical transport for the trace gas under observation.
- Subjects
ATMOSPHERIC deposition; TRACE gases; CARBON monoxide &; the environment; GAS measurement; STRATOSPHERE
- Publication
Atmospheric Chemistry & Physics Discussions, 2017, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2017-557