Open AccessPrecipitable water and the lognormal distribution
Author(s) -
Foster James,
Bevis Michael,
Raymond William
Publication year - 2006
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd006731
Subject(s) - precipitable water , log normal distribution , radiosonde , environmental science , climatology , zenith , atmospheric sciences , subtropics , meteorology , mathematics , geography , water vapor , geology , statistics , geodesy , fishery , biology
Histograms of precipitable water from radiosondes and zenith neutral delay estimated by GPS are found at many locations to follow a lognormal distribution. This observation is consistent with a theoretical expression for precipitable water based on moisture flux. Two unimodal cases are identified: the traditional lognormal distribution is commonly found in subtropical and temperate climates while tropical oceanic environments tend to exhibit a reversed lognormal form. Bimodal cases, formed by combinations of either or both of these unimodal distributions, are found where seasonal (e.g., monsoons) or climatic (e.g., El Niño) variations generate distinct precipitable water modes with rapid transitions between them. This connection with the lognormal distribution suggests a basis for the parameterization both of precipitable water in climate models as well as of the delay due to water vapor in atmospheric models used for space geodesy.