Measurements of the movement of the jet streams at mid-latitudes, in the Northern and Southern Hemispheres, 1979 to 2010 Dept. of Atmospheric and Oceanic Science, University of Maryland, College Park, MD, 20742-2425, USA
30 Aug 2012
Received: 22 August 2011 – Published in Atmos. Chem. Phys. Discuss.: 22 November 2011 Abstract. Previous studies have shown that the mean latitude of the sub-tropical jet
streams in both hemispheres have shifted toward the poles over the last few
decades. This paper presents a study of the movement of both the subtropical
and Polar fronts, the location of the respective jet streams, between 1979
and 2010 at mid-latitudes, using total ozone measurements to identify the
sharp horizontal boundary that occurs at the position of the fronts.
Previous studies have shown that the two fronts are the boundaries of three
distinct regimes in the stratosphere, corresponding to the Hadley, Ferrel,
and polar meridionally overturning circulation cells in the troposphere.
Over the period of study the horizontal area of the Hadley cell has
increased at latitudes between 20 and 60 degrees while the area of the Polar
cell has decreased. A linear regression analysis was performed to identify
the major factors associated with the movement of the subtropical jet
streams. These were: (1) changes in the Tropical land plus ocean
temperature, (2) direct radiative forcing from greenhouse gases in the
troposphere, (3) changes in the temperature of the lower tropical
stratosphere, (4) the Quasi-Biennial Oscillation, and (5) volcanic
eruptions. The dominant mechanism was the direct radiative forcing from
greenhouse gases. Between 1979 and 2010 the poleward movement of the
subtropical jet streams was 3.7 ± 0.3 degrees in the Northern Hemisphere
and 6.5 ± 0.2 degrees in the Southern Hemisphere. Previous studies have
shown that weather systems tend to follow the jet streams. The observed
poleward movement in both hemispheres over the past thirty years represents
a significant change in the position of the sub-tropical jet streams, which
should lead to significant latitudinal shifts in the global weather patterns
and the hydrologic cycle.
Revised: 04 July 2012 – Accepted: 16 August 2012 – Published: 30 August 2012
Citation: Hudson, R. D.: Measurements of the movement of the jet streams at mid-latitudes, in the Northern and Southern Hemispheres, 1979 to 2010, Atmos. Chem. Phys., 12, 7797-7808, doi:10.5194/acp-12-7797-2012, 2012.