Prediction of oceanic duct propagation from climatological data

Techniques are described for predicting the effect of the "oceanic duct" in increasing the coverage of low-sited microwave radars. Prediction is made on a monthly basis using statistical data on sea temperature, air temperature, humidity, and wind speed. A large area in the northwest Pacific is used to illustrate the methods used. The basic prediction approach is to deduce refractive index profiles from available data parameters and to use Schelkunoff\´s ducting criteria to predict radar propagation effects. Monthly contours are then drawn over the area for each radar band showing the probability of extended coverage.