Spatiotemporal Variability of High-Altitude Jet Streams from Satellite Measurements

Resumo

Results of an investigation into the spatiotemporal variability of the main characteristics of jet streams (JSs) in the upper troposphere of the Northern Hemisphere in the field of view of European geostationary meteorological satellites for the period 2007–2015 are presented. The JS characteristics are obtained using an automated method for calculating the horizontal wind velocity profile based on atmospheric sounding data from the SEVIRI radiometer in the 6.2-μm water vapor channel. Significant linear trends of most JS characteristics are revealed. It is shown that the relative increase in the number of JSs and their effective lifetime were 25 and 22%, respectively, and the relative decrease in the maximum wind speed on the axis and the horizontal velocity gradient on the cyclonic and anticyclonic sides were 7, 13, and 20%. The annual variation is most pronounced for the number of JSs, their maximum velocity, and average area and width. One characteristic feature is the synchronous annual variability of the maximum velocity and width of JSs determined by the isotach level V = 30 m/s. A pronounced horizontal asymmetry of the wind-velocity profile in JSs is noted. A stable annual oscillation and its harmonics are observed in amplitude spectra and waveletograms of time series of most daily and monthly mean characteristics. Significant oscillations were observed with periods of 19–23 and 37–39 days and 26.5–27.5, 35–37, and 42–45 months.