Verification of the mesospheric winds within the Canadian Middle Atmosphere Model Data Assimilation System using radar measurements

In the standard version of Canadian Middle Atmosphere Model Data Assimilation System (CMAM‐DAS), meteorological observations are assimilated only in the troposphere and stratosphere with no increments applied in the mesosphere. The mesospheric response is thus entirely due to internal model dynamics. This paper examines the influence of the assimilation of tropospheric and stratospheric observations upon the simulation of the mesospheric winds at middle and high northern latitudes in the CMAM‐DAS. The modeled mesospheric horizontal winds are verified using radar observations. Results show that the CMAM‐DAS can capture the variability of the observed tide‐removed mean horizontal winds in the mesosphere, especially for the short‐term variability during midwinter major sudden stratospheric warmings. This indicates that the mesospheric state is strongly constrained by the state of the lower atmosphere in the CMAM‐DAS. This work provides further evidence for the coupling of the mesosphere with the lower atmosphere and demonstrates that the CMAM when constrained by tropospheric and stratospheric observations can provide a realistic description of mesospheric wind variability at middle and high northern latitudes, especially in winter. This is the first comprehensive report of comparison of CMAM‐DAS analyses with radar measurements of tide‐removed mean horizontal winds in the mesosphere. Key Points The slaving of the mesosphere to the lower atmosphere