The imperfect relationship between dryline intensity and mesoscale confluence

The relationship between confluence and the contraction of thermodynamic gradients along most atmospheric boundaries is well understood. In most cases, confluence dominantly forces frontogenesis. Drylines, however, owe their structure to a number of factors unique to the region (e.g., terrain slope) and the background environment (e.g., vertical gradients of specific humidity, stratification). As such, one might expect the relationship between dryline intensity (i.e., the horizontal specific humidity gradient) and a single predictor, such as horizontal confluence, to be imperfect.

Using a recently-constructed two-year climatology for dryline events in the West Texas Mesonet domain, the correlation between dryline intensity and confluence is examined. A stepwise multiple linear regression method is employed to identify significant predictors for dryline intensity and confluence, as well as the normalized difference between the two. The results of the study will provide a context for further discussion of mesoscale controls on dryline structure, including topography and variations in land use.

Following from the conclusions, hypotheses germane to the proposed Simultaneous Observations of the Near-Dryline Environment (SONDE) Project will be introduced. SONDE will focus on the ground-based and airborne observation of drylines in West Texas during the spring of 2008.