Nested Grid Model Performance during Cold Offshore and Warm Onshore Flow Over the Gulf of Mexico.

摘要

During the cool season, cold air outbreaks push into the southern United States, across the Gulf coast, and into the Gulf of Mexico. The cycle of cold air outbreak and return flow over the Gulf of Mexico has been defined by Crisp and Lewis (1992) as the return flow cycle. The cycle involves two (2) distinct phases. The first phase of the cycle, known as the offshore flow phase, is defined as the movement of cold/dry air from the continent to the ocean. The second is defined as the movement of warmer/more moist air from the ocean to the continent and is called the onshore (or return) flow phase. The importance of the return flow cycle cannot be overemphasized. Forecasts of temperature, humidity, clouds, and precipitation along the Gulf coast and farther north are directly dependent upon accurate predictions of air mass modification over the Gulf. Operational forecasters depend heavily on outputs from numerical weather prediction models in preparing their daily suite of products. Since correct simulations of the return flow cycle are critical, an evaluation of Nested Grid Model (NGM) performance was conducted during the cool season of 1988. Emphasis was placed on determing model strengths and weaknesses during the return flow cycle.