Geomagnetic Storms and Wintertime 300-mb Trough Development in the North Pacific-North America Area

Abstract

This study confirms, for seven additional winters, a relationship discovered earlier between geomagnetic storms and subsequent deepening of 300-mb troughs. For this study a trough which moves into or is formed within the Gulf of Alaska area on the second to the fourth day after a geomagnetic storm, is defined as a key trough; it is found that key troughs tend to undergo a greater degree of subsequent intensification than non-key troughs. A vorticity index is computed in addition to the trough index used in earlier studies, and both indices show the same tendency. In the final section we speculate on possible causes for the relationships discovered.