Return Flow in the Gulf of Mexico. Part I: A Classificatory Approach with a Global Historical Perspective

Abstract

Abstract Return-flow events have been examined with the aid of a classification scheme that identifies each event with cold air masses that invade the Gulf during the cool season (February-March). These air masses were classified as either continental polar (cP), maritime polar (mP), or a mix of two or more of these basic types (MIX in future reference). Each event was viewed as a cycle in which the first phase represented an offshore flow typifying the cold-air outbreak over the Gulf and the second phase was associated with the return of modified air to the continent. Surface data for a 12-yr period, 1978–89, were used to make a statistical analysis of the event and each of its phases. The principal results of the study are 1) a total of 127 events occurred in this cool season over the 12-yr period. The relative percentages of mP, cP, and MIX air masses are 28%, 20%, and 52%, respectively. A median of 10.5 return-flow events occurred in the cool season where the MIX category was the dominant regime. The ...