Sensitivity of troposcatter communications to the resolution of radiosonde data

Numerical models are used to study the vertical resolution effects of radiosonde data on calculation of troposcatter communication system losses under anomalous propagation conditions. System losses were computed for all-data and for reduced-sample profiles of the same vertical radiosonde profile. System performance is evaluated first by using original radiosonde data with all sampling levels as measured by the Saudi Arabian Meteorological Environmental Protection Agency (MEPA) and second by using a reduced version of the same data as reported by the World Meteorological Organization (WMO) using their standard methods and procedures for reporting radiosonde data. The MEPA and the WMO profiles give approximately the same losses. Therefore, the WMO profiles provide adequate atmospheric data for troposcatter communication loss calculations. However, the percent of the beam lost by trapping in cases where ducting is a factor shows a marked difference between profiles of different resolutions. Much more of the beam appears to be trapped in the models using the MEPA higher-resolution profiles. In severe ducting cases, trapping losses predicted using the MEPA data are much higher than those predicted using the WMO profiles. This indicates that in an environment with a high probability of ducting, a better prediction of system performance is obtained with higher-resolution data.