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.

The LaGrange Tornado during VORTEX2. Part I: Photogrammetric Analysis of the Tornado Combined with Single-Doppler Radar Data

“…Photogrammetric analysis is a technique that can extract quantitative information from a picture such as the dimensions of a cloud or the condensation funnel accompanying a tornado (e.g., Malkus 1952;Rasmussen et al 2003;Zehnder et al 2007). Photogrammetry requires knowledge of the camera location and precise azimuth angles to targets located on the horizon in the picture.…”

Behavior and Structure of Convective Clouds Developing around a Mountainous Area Observed by Stereo Photogrammetry and Ka-Band and X-Band Radars: Case Study of Northern Kanto, Japan

“…One of the results of this study suggests that the interaction of the thermally induced local circulation and the mesoscale convergence zone is an important trigger for the formation of strong updraft that can intrude into the stable layer with a small convective available potential energy (CAPE) condition (Kalthoff et al 2009;Barthlott et al 2010;Bennett et al 2011). In the United States, the Cumulus, Photogrammetric, In situ, and Doppler Observation Experiment (CUPIDO) investigated convection from a very early stage using stereo photogrammetric analysis, soundings, and airborne sensor observation around the Santa Catalina Mountains, Arizona (Zhender et al 2007). They concluded that successive formation of convective clouds created appropriate conditions for deep convection (Zhender et al 2009).…”

An Integrated Damage, Visual, and Radar Analysis of the 2013 Moore, Oklahoma, EF5 Tornado

“…2 Social media were used to collect imagery and video from amateur storm chasers and news crews. Azimuth and elevation grids were superimposed on select photographs and video frames using photogrammetric techniques that are well documented in the literature (e.g., Rasmussen et al 2003;Zehnder et al 2007;Wakimoto et al 2011;Atkins et al 2012). By measuring the azimuth angles of known landmarks in the photos, the grid uncertainty is estimated to be 0.1°.…”