Winter 2018 major sudden stratospheric warming impact on midlatitude mesosphere from microwave radiometer measurements

摘要

The impact of a major sudden stratospheric warming (SSW) in theArctic in February 2018 on the midlatitude mesosphere is investigated byperforming the microwave radiometer measurements of carbon monoxide (CO) andzonal wind above Kharkiv, Ukraine (50.0∘ N, 36.3∘ E).The mesospheric peculiarities of this SSW event were observed using arecently designed and installed microwave radiometer in eastern Europe for thefirst time. Data from the ERA-Interim and MERRA-2 reanalyses, as well as theAura microwave limb sounder measurements, are also used. Microwaveobservations of the daily CO profiles in January–March 2018 allowed for theretrieval of mesospheric zonal wind at 70–85 km (below the wintermesopause) over the Kharkiv site. Reversal of the mesospheric westerly fromabout 10 m s−1 to an easterly wind of about −10 m s−1 around 10February was observed. The local microwave observations at our Northern Hemisphere (NH)midlatitude site combined with reanalysis data show wide-ranging dailyvariability in CO, zonal wind, and temperature in the mesosphere andstratosphere during the SSW of 2018. The observed local CO variability canbe explained mainly by horizontal air mass redistribution due to planetarywave activity. Replacement of the CO-rich polar vortex air by CO-poor air ofthe surrounding area led to a significant mesospheric CO decrease over thestation during the SSW and fragmentation of the vortex over the station atthe SSW start caused enhanced stratospheric CO at about 30 km. The resultsof microwave measurements of CO and zonal wind in the midlatitude mesosphereat 70–85 km altitudes, which still are not adequately covered byground-based observations, are useful for improving our understanding of theSSW impacts in this region.