{{}S{}}tratospheric winds: longitudinal distribution and long-term trends

Abstract

The wind is very important parameter of the stratospheric dynamics which can be affected by many factors like tropospheric North Atlantic Oscillation (NAO) or El Nino Southern Oscillation (ENSO), stratospheric Quasi-biennial Oscillation (QBO) or Sudden Stratospheric Warming (SSW) and solar activity. Due to lack of direct observations we have to use reanalysis data, here NCEP/NCAR reanalysis. The behaviour and trends of wind and its meridional component is analysed in this paper. The influence of NAO on trend in wind is significant in the lower stratosphere (100 hPa) in Atlantic sector; the trend is also affected by QBO, whereas influence of SSW is rather minor and observable only in the middle stratosphere (10 hPa). The most interesting result seems to be the longitudinal distribution of the meridional wind component. We identify two-core structure of strong but opposite winds, one at each hemisphere at 10 hPa, and a four-core structure at 100 hPa. These structures are not associated with tides. However, they appear to be related to the well-pronounced Aleutian pressure high at the 10 hPa level.