Return Flow in the Gulf of Mexico. Part II: Variability in Return-Flow Thermodynamics Inferred from Trajectories over the Gulf

Abstract

Abstract A return-flow case study is examined with the benefit of an unprecedented set of observations obtained during the Gulf of Mexico Experiment (GUFMEX). This case represents the return of modified continental air to the coastal plain in mid-February, and the work is designed to complement the classificatory study of return flow that is found in the companion paper by Crisp and Lewis. Surface air trajectories are combined with land- and ocean-based upper-air data to methodically follow the airmass modification process from the exit point off the Gulf coastal plain to its subsequent entry point on land. Upper-air data from the U.S. Coast Guard (USCG) ship Salvia are especially valuable in this tracking process, but data from an oil platform at the edge of the continental shelf, as well as special onshore observations, significantly contribute to a macroscopic tracking of air involved in the return flow. Results indicate that the warming and moistening process is complicated and requires careful assess...