Modeling and Analysis of the Combined Effects of Meteorological Variables on Atmospheric Evaporative Potential Using Structural Equation (Case Study: Tabriz City)

Evaporation from a water level is affected by non-meteorological and meteorological factors. In this regard the role of meteorological factors as determining elements is more than nonmeteorological ones. In this study, path analysis and partial correlation methods were used for the purpose of modeling and evaluating of the direct and indirect influences of the meteorological factors on the evaporation in the warm period of Tabriz city. After normalization of some data series of variables through Johnson functions, the potential evaporation Path model of the atmosphere was formed by use of the structural equation. The output of multiple correlations showed a significant 0.913 amount of the optimum model. The evaluation of the indices for the direct and indirect paths of the variables proportional to the evaporation indicated that temperature and pressure had the highest direct effects on evaporation respectively, while the vapor pressure saturation deficit showed the highest correlation with evaporation. Also in the most cases, a variable such as air pressure in a reverse path with its direct effect showed a correlation and this is the reason for the reduction of the correlation between this variable and evaporation. Generally, the results indicated that the application of structural equation and the differential correlation can model and discover the complicated and synthetic relationship of the meteorological variables in an acceptable extent.