An evaluation of the impact of variable temporal and spatial data resolution upon IREPS

Abstract

Atmospheric refractive index gradients significantly modify the path of electromagnetic (EM) waves as they propagate through the atmosphere. Accordingly, the performance of U.S. Navy (EM) systems can be wither degraded or enhanced due to atmospheric conditions which affect atmospheric refractive index profiles. The Integrated Refractive Effects Prediction System (IREPS) version 2.2 is the latest software developed by Naval Ocean Systems Center (NOSC) to predict atmospheric refraction and its resulting effect on EM systems. Specific environmental parameters are used as input data to produce various output products to be used by the tactician in planning the optimum use of naval assets. As with any model, the quality and accuracy of the resulting output is directly related to the quality and timeliness of the input data. This thesis study shows the importance of timely, high resolution data, for input into the IREPS version 2.2 program, in order to obtain realistic atmospheric refractive and corresponding EM system performance predictions. A continentally derived data set is used to compare the results off using high resolution versus low resolution data as input into IREPS, and to qualitatively show how quickly the refractive structure of the atmosphere can vary with time. A second data set from an over ocean experiment attacks to horizontally homogeneous atmosphere assumption which appears to be frequently incorrectly applied. Finally, a statistical comparison is performed to evaluate the extent to which the natural variability of the atmosphere can result in significant variations of atmospheric refractivity that could affect naval EM systems.