Diagnosis of the Low-Level Jet using a sounding analysis scheme and the ETA model, a case study

Abstract

The LLJ transports moisture northward from the Gulf of Mexico into the Great Plains. Proper detection of the LLJ is important in aviation and forecasting. Standard atmospheric charts are usually insufficient in properly depicting the structure and intensity of the LLJ. This limitation arises because the LLJ climbs in altitude as it flows northward. A sounding analysis scheme is presented as an alternative to currently existing LLJ detection methods. The intensity and aerial coverage of the LLJ were studied using this analysis scheme during a case study from May 1995. The data set used consisted of 80-km Eta model output. When compared to other methods, the developed analysis scheme showed more LLJ detail and structure. The LLJ appeared with multiple cores as opposed to one long and continuous core, as typically depicted at the 850-mb level. This fits in with current research that shows the existence of multiple LLJ cores caused by different factors, such as synoptic influences, orography, and a strong low-level pressure gradient. The method developed in this research is proposed as an alternate method for LLJ detection.