Strong Quarterdiurnal Tides in the Mesosphere and Lower Thermosphere During the 2019 Arctic Sudden Stratospheric Warming Over Mohe, China

Abstract

AbstractWe present an analysis of a quarterdiurnal tide (QDT) during the 2019 Arctic sudden stratospheric warming (SSW) event. The analysis is based on data obtained from a meteor radar located at Mohe (MH, 53.5°N, 122.3°E), China. The enhancement of the QDT amplitude is observed during the SSW and the maximum QDT amplitude is about 10 m/s in both neutral wind components. Using the meter radar measurements at MH in the period from August 2011 to April 2019, a probability density function of the QDT amplitude is estimated. The probability of the QDT amplitude larger than 8 m/s is less than 1% at MH. A clear seasonal variability of the QDT amplitude is apparent with the maximum amplitudes that appeared in winter. Based on our analysis, the seasonal variability of the QDT is not the main reason that amplified the QDT. According to the bispectral and bicoherence analyses, nonlinear interaction between tidal waves may contribute to the enhancement of the ODTs. The nonlinear interaction between two semidiurnal tides (SDTs) is important, while the effect of the nonlinear interaction between the diurnal tide and the terdiurnal tide is secondary. It may be possible that the effect of the 2019 SSW amplifies the SDT first and then the QDT is generated via nonlinear interaction of SDTs.