Characteristics of the subtropical jet stream over the North Atlantic from reanalysis data

Abstract

Variability of characteristics (latitudinal location and wind speed) of the subtropical jet stream in the Northern Hemisphere for the winter (December-February) and summer (June-August) seasons in 1958-2017 is investigated with NCEP/NCAR, JRA-55, NCEP/DOE, and ERA-Interim reanalysis data. It is shown that the jet is shifting to the equator (0.58°N per decade) and is increasing (0.51 m/s per decade) in the Atlantic sector (0°-60°W) during the winter season. In 2000-2017 a large contribution to these trends is made. The jet is shifting poleward (0.23°N per decade) and is increasing (0.35 m/s per decade) in the summer season. An analysis of variability of the characteristics of the subtropical jet stream is performed for 1958-1979 (cooling of the global surface temperature), 1979-2000 (warming of the global surface temperature), and 2000-2017 (stabilization of the global surface temperature). Correlations between the variability of the jet characteristics and the variability of the meridional upper-tropospheric temperature gradient, the position and intensity of the Azores High, the concentration of sea ice in the North Atlantic Ocean, the total ozone content, the index of the North Atlantic Oscillation, and the atmosphere vortex circulation in the Atlantic sector are found.