Wind analysis in complex terrain

Here at CIRP we are working to augment a near real-time data analysis system previously developed at the University of Oklahoma. The Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) is three-dimensional and applies a successive correction technique that converges to optimum interpolation under certain conditions. The analysis produces wind fields that reflect the observations but does not directly take into account the complex terrain nor the atmospheric stability. Additionally, ADAS diagnoses the vertical velocity from the analysis horizontal wind components via the traditional O'brien technique. We seek an alternative method to recover the vertical motion field that directly takes into consdideration both the thermodynamic structure of the atmosphere and topography. We are currently coupling this analysis system with a dynamic wind adjustment that guarantees mass conservation and, using an inverse Froude number, takes into account the ambient stability. The wind adjustment technique, originally developed for dispersion modeling, is adapted to the ADAS terrain-following coordinate. The initially unbalanced winds from the ADAS analyses are input. We compare the output wind fields to ADAS only analyses, a two-dimensional wind adjustment currently being used, and surface wind diagnostics determined from mesonet observations.