A paper published today in the Journal of Climate finds that relative humidity has been decreasing 0.5% per decade across North America during the 62 year period of observations from 1948-2010. Computer models of AGW show positive feedback from water vapor by incorrectly assuming that relative humidity remains constant with warming while specific humidity increases. The Miskolczi theory of a 'saturated greenhouse effect' instead predicts relative humidity will decrease to offset an increase in specific humidity, as has just been demonstrated by observations in this paper. The consequence of the Miskolczi theory is that additions of 'greenhouse gases' such as CO2 to the atmosphere will not lead to an increase in the 'greenhouse effect' or increase in global temperature.
Journal of Climate 2012 ; e-View
V. Isaac and W. A. van Wijngaarden*
Over 1/4 billion hourly values of temperature and relative humidity observed at 309 stations located across North America during 1948-2010 were studied. The water vapor pressure was determined and seasonal averages were computed. Data were first examined for inhomogeneities using a statistical test to determine whether the data was fit better to a straight line or a straight line plus an abrupt step which may arise from changes in instruments and/or procedure. Trends were then found for data not having discontinuities. Statistically significant warming trends affecting the Midwestern U.S., Canadian prairies and the western Arctic are evident in winter and to a lesser extent in spring while statistically significant increases in water vapor pressure occur primarily in summer for some stations in the eastern half of the U.S. The temperature (water vapor pressure) trends averaged over all stations were 0.30 (0.07), 0.24 (0.06), 0.13 (0.11), 0.11 (0.07) C/decade (hPa/decade) in the winter, spring, summer and autumn seasons, respectively. The averages of these seasonal trends are 0.20 C/decade and 0.07 hPa/decade which correspond to a specific humidity increase of 0.04 g/kg per decade and a relative humidity reduction of 0.5%/decade.
I am sorry to say it gives little bearing on what the global average h2o column amount is doing with respect the greenhouse effect (or the global average IR optical depth of the atmosphere).
First, let me remind you that the greenhouse effect (caused by the true absorbed surface upward LW flux density by greenhouse gases ) mutually depends on the total column amount of the IR absorbers and the spectral distribution of the surface upward radiation. There is a long way to go from a regional (USA, Canada) average surface h2o partial pressure trend to the trend in the true global average IR optical depth of the atmosphere. However, if you assume, that the published trends in the surface specific humidity and temperature is a representative global average, then the slight increase in temperature and h2o content really supports my theory of constant global average IR optical depth. The reason is that the increased surface temperature shifts the distribution of the spectral flux density towards the windows region and therefore reduces the flux absorption, while the increasing specific humidity tends to increase the IR absorption. The combined effect may be a constant greenhouse effect (as predicted theoretically by the constant IR optical depth of 1.87).
Further, I have serious reservations with respect the methodology of the computations.
1 - Equation 1. is incorrect, the specific humidity depends on the actual surface pressure. Looking for very small variations this dependence might not be negligible
2 - Equation 2 (a version of the Bolton equation) is for the computation of saturated h2o pressure over water. I assume, that in winter time large areas are snow and ice covered and the temperature is well below freezing, therefore the use of the saturation pressure formula over ice is justified. (ei = 6.112 exp(22.46 t/(272.62 + t)) , WMO, CIMO 2008).
3 - The argument that the positive h2o pressure trend and the negative relative humidity trend comes from Equation 7 is not quite true. The h2o pressure was computed from the saturation pressure, therefore the h2o partial pressure should have the same dependence on the ambient temperature as the saturation h2o pressure. The relative humidity is a true stochastic variable depending only on the instantaneous movement of the water vapor in the air.
4. - The h2o partial pressure (or h2o number density) has a strong constraint with respect the actual total pressure (and number density), ie. the partial pressures of all atmospheric constituents should add up to the total pressure. The trends in the observed surface pressure were not presented, therefore one may not know where the excess h2o was coming.
This paper by no means is a proof of the existence of some kind of positive h2o feedback working in the global greenhouse effect.