Abstract
In this paper, a comparison of the impact of major sudden stratospheric warmings (SSWs) in the Arctic in February 2018 (SSW1) and January 2019 (SSW2) on the mid-latitude mesosphere is given. The mesospheric carbon monoxide (CO) and zonal wind in these two major SSW events were observed at altitudes of 70–85 km using a microwave radiometer (MWR) at Kharkiv, Ukraine (50.0°N, 36.3°E). Data from ERA-Interim and MERRA-2 reanalyses and Aura Microwave Limb Sounder measurements were also used. It is shown that: (i) The differences between SSW1 and SSW2, in terms of local variability in zonal wind, temperature, and CO in the stratosphere and mesosphere, were clearly defined by the polar vortex (westerly in cyclonic circulation) and mid-latitude anticyclone (easterly) migrating over the MWR station, therefore; (ii) mesospheric intrusions of CO-rich air into the stratosphere over the Kharkiv region occurred only occasionally, (iii) the larger zonal wave 1–3 amplitudes before SSW1 were followed by weaker polar vortex recovery than that after SSW2, (iv) the strong vortex recovery after SSW2 was supported by earlier event timing (midwinter) favoring vortex cooling due to low solar irradiance and enhanced zonal circulation, and (v) vortex strengthening after SSW2 was accompanied by wave 1–3 amplification in March 2019, which was absent after SSW1. Finally, the influence of the large-scale circulation structures formed in individual major SSW events on the locally recorded characteristics of the atmosphere is discussed.
Highlights
The troposphere–stratosphere–mesosphere interaction in the Northern Hemisphere (NH) is limited to the winter season, when the westerly zonal winds in the stratosphere favor a vertical propagation of planetary waves from the troposphere to stratosphere [1,2,3]
The purpose of this paper is to provide a comparison of the degree of perturbation introduced by two consecutive major stratospheric warming (SSW) on the mid-latitude mesosphere
The local and regional manifestations of the stratospheric warming event in January 2019 (SSW2) were compared with those occurring in February 2018 (SSW1; [26])
Summary
The troposphere–stratosphere–mesosphere interaction in the Northern Hemisphere (NH) is limited to the winter season (which usually lasts from November to April), when the westerly zonal winds in the stratosphere favor a vertical propagation of planetary waves from the troposphere to stratosphere [1,2,3]. One of the most dramatic examples of the wintertime troposphere–stratosphere–mesosphere interaction is major sudden stratospheric warming (SSW) [2,4], which has a strong impact on the middle atmosphere and provides valuable information about atmospheric vertical exchange These events are mostly NH phenomena [4,5,6], as the more inhomogeneous topography at northern mid-latitudes produces stronger planetary wave activity than in the Southern Hemisphere [1,7]. Charlton and Polvani [5] described the main characteristics of different SSW types based on reanalysis data from 1958 to 2002 They developed an algorithm based on the WMO [11] definition, which identifies SSWs and classifies them into events that either split or do not split the stratospheric polar vortex. The existence of a bell-shaped “continuum” of warming events without distinction between the different SSW types, in terms of dynamical coupling between the stratosphere and troposphere, has been described [4]
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