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The Seesaw in Winter Temperatures between Greenland and Northern Europe. Part III: Teleconnections with Lower Latitudes

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  • 1 Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309
  • | 2 National Center for Atmospheric Research, Boulder, CO 80307
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Abstract

Tropical teleconnections to the seesaw in winter mean temperatures between Greenland and northern Europe are described in terms of the trade winds, African precipitation, sea surface temperatures and Gulf Stream intensity as indicated by changes in relative sea levels. There is a statistically significant correlation between the strength of the northeast and southeast trades in the Atlantic during seesaw winters, but not in other winters. Latitudinal differences in the position of the ITCZ over Africa, as defined by the belt of heaviest precipitation, are seen between the two modes of the seesaw but not in other circulation types.

Relative sea levels on either side of the Gulf Stream show that geostrophic velocity of the surface current is out of phase with the strength of the trades in the North Atlantic Ocean during seesaw winters, which presumably indicates that in this region steric effects on the current prevail over the influence of the wind. Small-magnitude pressure anomaly patterns of the type seen during seesaw winters are present in autumns preceding those winters, and sea surface temperature anomalies associated with the seesaw occur at all latitudes in summers and autumns preceding, and springs following seesaw winters.

Abstract

Tropical teleconnections to the seesaw in winter mean temperatures between Greenland and northern Europe are described in terms of the trade winds, African precipitation, sea surface temperatures and Gulf Stream intensity as indicated by changes in relative sea levels. There is a statistically significant correlation between the strength of the northeast and southeast trades in the Atlantic during seesaw winters, but not in other winters. Latitudinal differences in the position of the ITCZ over Africa, as defined by the belt of heaviest precipitation, are seen between the two modes of the seesaw but not in other circulation types.

Relative sea levels on either side of the Gulf Stream show that geostrophic velocity of the surface current is out of phase with the strength of the trades in the North Atlantic Ocean during seesaw winters, which presumably indicates that in this region steric effects on the current prevail over the influence of the wind. Small-magnitude pressure anomaly patterns of the type seen during seesaw winters are present in autumns preceding those winters, and sea surface temperature anomalies associated with the seesaw occur at all latitudes in summers and autumns preceding, and springs following seesaw winters.

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