Low-Level Jet Climatology from Enhanced Rawinsonde Observations at a Site in the Southern Great Plains

Abstract

Abstract A climatology of the Great Plains low-level jet (LLJ) is developed from 2 yr of research rawinsonde data obtained up to eight times per day at a site in north-central Oklahoma. These data have better height and time resolution than earlier studies, and show that jets are stronger than previously reported and that the heights of maximum wind speed are closer to the ground. LLJs are present in 47% of the warm season soundings and 45% of the cold season soundings. More than 50% of the LLJs have wind maxima below 500 m above ground level (AGL). Because the 404-MHz radar profiler network in the central United States has its first data points at 500 m AGL, it is likely to miss some LLJ events and will have inadequate vertical resolution of LLJ wind structure. Previous studies have identified LLJs on the basis of a wind speed profile criterion. This criterion fails to separate the classical southerly LLJs from the less frequent northerly jets, which differ in both structure and evolution. Classical sout...