DISTORTION AND OCCLUSION OF COLD FRONTS UNDER THE INFLUENCES OF OROGRAPHY

Following classical theory, a two-layer frontal model is designed. It assumes that frontal surface is the zero-order discontinuty of density. In this paper, the model is used to study orographically distorted and occluded fronts. It is indicated that the distortion and occlusion of cold fronts are different under different conditions of orography. Frontal intensity has also influences on the distortion and occlusion. Some rules are revealed and compared with observations. In addition, we have analysed the vertical structure of cold front above mountain and found that frontal surface may be bulged under the influence of orography when it climes the mountain. The bulge of frontal surface is just like the bore which is pointed out by Lone(1972) when he analvsed fluid over obstacles.