TRENDS IN CYCLONE AND ANTICYCLONE FREQUENCY AND COMPARISON WITH PERIODS OF WARMING AND COOLING OVER THE NORTHERN-HEMISPHERE

Available datasets and pertinent climatological studies have been examined to show the statistical trends in frequency of cyclone and anticyclone events for the Northern Hemisphere during periods of warming and cooling this century (as determined from the NASA temperature dataset). Results tend to indicate a decrease in events during cooling and an increase during warming, although further study is warranted. A second objective of this study has been to show the discontinuity introduced by the National Meteorological Center in 1970-71 in the automated 500-mb map analysis of cyclone events.