A Stereo Photogrammetric Technique Applied to Orographic Convection

Abstract

This paper describes a technique for photogrammetric analysis of stereo pairs of images that is applied to the study of orographic convection. The technique is designed for use with digital images and assumes detailed knowledge of the camera properties (focal length and imaging chip) and that the position and orientation are known as a first guess. An iterative scheme using known landmarks on the frame is used to determine the camera orientation. The scheme is accurate to 10?100 m at a distance of 15 km from the camera pair. The transition from shallow to deep convection over the Santa Catalina Mountains in southern Arizona on 26 July 2005 is presented. The three-dimensional structure of the visible portion of the cloud is determined and compared with the composite reflectivity from the National Weather Service Weather Surveillance Radar-1988 Doppler radar and the tropopause height from the 1200 UTC sounding in Tucson, Arizona, providing additional validation of the scheme. The shallow to deep transition is characterized by tracking individual turrets and determining the maximum height of the cloud top. The cloud tops were limited to beneath 6000 m MSL for the first 1.5 h followed by the development of deep convection. The motion of the turrets and location of the eventual deep convection were consistent with the idea that moistening by shallow convection conditions the atmosphere for further development.