diff --git a/utilities/qair2rh.m b/utilities/qair2rh.m new file mode 100644 index 0000000000000000000000000000000000000000..d148bd821e5d2332b2681c0828ed778bfcedde87 --- /dev/null +++ b/utilities/qair2rh.m @@ -0,0 +1,29 @@ +function rh = qair2rh(qair, temp, varargin) +% Convert specific humitidy to relative humidity. +% +% INPUTS: +% qair - Specific humidity. Dimensionless ratio of water mass / +% total air mass. +% temp - Temperature. Celsius. +% press - Pressure, optional. Millibar. Assume as 1013.25 if +% missing. +% +% OUTPUT: +% rh - relative humidity, ratio of actual water mixing ratio to +% saturation mixing ratio. +% +% NOTES: +% Translated from the R code here: +% http://earthscience.stackexchange.com/questions/2360 +% +% Author(s): +% Pierre Cazenave (Plymouth Marine Laboratory) + +if nargin == 2 + press = 1013.25; +end +es = 6.112 * exp((17.67 * temp) / (temp + 243.5)); +e = qair * press / (0.378 * qair + 0.622); +rh = e / es; +rh(rh > 1) = 1; +rh(rh < 0) = 0;