Fourth AMS Student Conference


Diagnosis and Prediction of the Refractive Index Structure Parameter on the Mesoscale

Benjamin W. Hershey, University of North Dakota, Grand Forks, ND; and K. A. Naber, M. Askelson, C. M. Paulsen, J. S. Tilley, and S. S. Kumar

The U.S. Army uses electromagnetic surveillance techniques in the battlefield. Because atmospheric conditions can significantly influence electromagnetic waves and, thus, can impact Army operations, knowledge of atmospheric conditions and their impact on electromagnetic waves is highly valuable to the Army. For instance, knowing locations and strengths of refractivity gradients can help in understanding how electromagnetic waves propagate through the atmosphere. Large gradients in temperature, pressure, and water vapor pressure that directly affect refractivity gradients can be found in both synoptic and mesoscale systems. Gradients in synoptic scale systems are generally easier to decipher and less extreme than those found in mesoscale systems, which can be difficult to accurately evaluate owing to lack of observations. Along with refractivity, the refractive index structure parameter Cn2 can also be estimated from atmospheric analyses and forecasts. To understand better the mesoscale structure of refractivity and optical turbulence variations in the atmosphere, software that outputs gridded refractivity and Cn2 fields from NOAA Forecast Systems Laboratory Local Analysis Prediction System (LAPS) analyses as well as forecasts from the MM5 and WRF mesoscale models has been developed. In this paper, we examine analyses and forecasts of refractivity and Cn2 for cases covering two domains over the northern and southern plains of the United States. Analyses of output from these algorithms indicates that both analyzed and forecast refractivity gradients can be quite large in synoptic and mesoscale systems, resulting in electromagnetic wave path changes. Preliminary validation efforts using available data from soundings and wind profilers will also be presented.

Poster Session 1, Student Conference Poster Session
Sunday, 9 January 2005, 5:30 PM-5:30 PM

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