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Variability of monthly time fraction of excess of atmospheric propagation parameters
Author(s) -
Mawira A.
Publication year - 1997
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 - 10.1029/97rs01398
Subject(s) - log normal distribution , fraction (chemistry) , gamma distribution , pooling , exponential function , statistics , exponential distribution , conditional probability distribution , mathematics , attenuation , environmental science , atmospheric sciences , physics , chemistry , computer science , mathematical analysis , organic chemistry , artificial intelligence , optics
This paper investigates the variability of the monthly time fraction of excess of atmospheric propagation parameters. In the first part of the paper a theoretical investigation is carried out regarding the relationship between the variability of monthly time fraction of excess vis‐a‐vis the variability of the annual‐worst‐month time fraction of excess. It is shown that the tail of the distribution of the annual‐worst‐month time fraction of excess can be derived from the average distribution of the monthly time fraction of excess without requiring detailed knowledge of the seasonal behavior of the propagation. In the second part of the paper the modeling of the average distribution of the monthy time fraction of excess (the parent distribution) is investigated using some 92 site years of data (from slant path attenuation and transhorizon measurements). Three competing models were investigated: the conditional exponential, the conditional lognormal, and the shifted gamma distribution. For the testing of the suitability of the model a novel data pooling method is applied. The tests results show the shifted gamma model as the best model, followed by the conditional exponential model and then the conditional lognormal model.