Sun, D.-Z., C. Covey, and R. S. Lindzen, 2001: Vertical correlations of water vapor in GCMs. Geophys. Res. Lett., 28, 259-262.
Correlations of tropical mean water vapor with its surface values have been calculated for all AMIP1 models and some of the AMIP2 models. The previously noted discrepancy between the GFDL model and rawinsonde data also exists for other models: the interannual correlations of water vapor with its surface values decline to smaller values in observations than in the models. This discrepancy is reduced somewhat after the data from the models were sampled at the same locations where observational data were collected, but remains significant even at low levels. Significant discrepancy between models and observations also exists in the regressions of water vapor on temperature, suggesting something other than differences in the noise level as the main cause for the discrepancy in the vertical correlations between model and rawinsonde observations.