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K factor statistics for subrefraction in the mid‐Atlantic coast of the United States
Author(s) -
Goldhirsh Julius,
Dockery G. Daniel
Publication year - 2001
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2000rs002326
Subject(s) - statistics , climatology , environmental science , meteorology , geography , atmospheric sciences , mathematics , physics , geology
Statistics of “equivalent K factor” are derived for the mid‐Atlantic coast of the United States. These statistics are associated with subrefraction using 3 years of near‐continuous line‐of‐sight link signal measurements at 4.7 GHz in the mid‐Atlantic coast of the United States. Probabilities are derived for a family of threshold levels of K factors ranging from 0.6 to 1.0 which are sustained over durations exceeding 1–5 hours. An analytical model is derived that characterizes this family of curves with excellent accuracy. It is, for example, demonstrated that for 6% of the average year the K factor is smaller than 1 for durations greater than 1 hour in the mid‐Atlantic coast of the United States. Caveats that should be considered in applying these results are reviewed. Monthly probabilities of K factor statistics reveal that the winter and early spring months dominate. For example, during February of year 1 and December of years 2 and 3 the K factors were smaller than 0.8 for periods exceeding 2 hours at the probabilities of 11.5%, 12.0%, and 11.5%, respectively. This result is consistent with the fact that cold water conditions and warm overlying moist air are more prevalent during the winter season. These conditions represent the correct meteorological ingredients for extreme subrefraction to occur. Annually, the K factor was smaller than 0.8 with durations greater than 1 hour at a probability of 3.2%.