HF MUF (Maximum Usable Frequencies) Model Uncertainty Assessment.
NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA
Pagination or Media Count:
To assess the accuracy of MUF model prediction, a statistical analysis of observed oblique sounder median maximum observed frequencies MOF and predicted maximum usable frequencies MUF was conducted. A data base consisting of 13,054 hours of oblique sounder MOFs measured on 70 paths were compared against the predicted MUF values from MINIMUF-3.5, MINIMUF 85 and an unrelated MUF model, the HF Broadcast WARC Model HFBC 84. The data was screened into subsets to determine the effect of particular paths, path length and orientation, season, month, latitude, sunspot number, diurnal trends, geographic region and sounder type. The accuracy of all three models was very close, with the MINIMUF-3.5 model having the lowest rms error of 4.44 MHz. MINIMUF 85 was next with an rms error of 4.58 MHz and HFBC 84 was last with an error of 4.67 MHz. Correlation was good for all three models. Coefficients were .824, .819 and .827 for MINIMUF-3.5, MINIMUF 85 and HFBC 84, respectively. The primary difference between MINIMUF-3.5 and MINIMUF 85 appeared when detailed analysis of the accuracies was conducted. When the variation in error was noted as a function of season, sunspot number, or range, for instance, there was less variation in the accuracy of MINIMUF 85.
- Radiofrequency Wave Propagation