Possible solar wind effect on the Northern Annular Mode and northern hemispheric circulation during winter and spring
Lu, Hua; Jarvis, Martin J.; Hibbins, Robert E.. 2008 Possible solar wind effect on the Northern Annular Mode and northern hemispheric circulation during winter and spring. Journal of Geophysical Research, 113 (D23), D23104. 15, pp. 10.1029/2008JD010848Before downloading, please read NORA policies.
Statistically measurable responses of atmospheric circulation to solar wind dynamic pressure are found in the Northern Hemisphere (NH) zonal-mean zonal wind and temperature, and on the Northern Annular Mode (NAM) in winter and spring. When December to January solar wind dynamic pressure (PswDJ) is high, the circulation response is marked by a stronger polar vortex and weaker sub-tropical jet in the upper to middle stratosphere. As the winter progresses, the Arctic becomes colder and the jet anomalies shift poleward and downward. In spring, the polar stratosphere becomes anomalously warmer. At solar maxima, significant positive correlations are found between PswDJ and the middle to late winter NAM all the way from the surface to 20 hPa, implying a strengthened polar vortex, reduced Brewer–Dobson circulation and enhanced stratosphere-troposphere coupling. The combined effect of high solar UV irradiance and high solar wind dynamic pressure in the NH middle to late winter is enhanced westerlies in the extratropics and weaker westerlies in the subtropics, indicating that more planetary waves are refracted toward the equator. At solar minima, there is no correlation in the NH winter but negative correlations between PswDJ and the NAM are found only in the stratosphere during spring. These results suggest possible multiple solar inputs that may cause refraction/redistribution of upward wave propagation and result in projecting the solar wind signals onto the NAM. The route by which the effects of solar wind forcing might propagate to the lower atmosphere is yet to be understood.
|Programmes:||BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Sun Earth Connections|
|NORA Subject Terms:||Meteorology and Climatology
|Date made live:||05 Feb 2009 15:00|
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