We have recently developed and built a mobile cloud photogrammetric system as part of the Mesoscale Dynamics and Modeling Laboratory (MDML) activities at DRI. The photogrammetric system consists of two synchronized and aligned digital cameras that can be easily transported into back country and setup on short notice. The system can measure full 3d coordinates of any visible cloud feature at distances up to several kilometers, with snapshots at repeated time intervals only a few seconds apart.

This photogrammetric system was deployed for the first time in the Terrain-induced Rotor Experiment (T-REX) in March and April 2006 for photo documentation of the time evolution of wave and rotor clouds over Owens Valley in the lee of the Sierra Nevada. Atmospheric rotors are intense low-level horizontal vortices that form along an axis parallel to, and downstream of, a mountain ridge crest, and are strongly coupled to both the overlying mountain waves as well as the underlying boundary layer. Rotor clouds are elongated cumulus clouds that form underneath mountain wave crests, at or near the mountain ridge height, and unlike smooth wave clouds further aloft, are quite unsteady displaying evidence of vigorous in-cloud and interfacial turbulence, particularly evident at the leading edge of the rotor.

In this poster, we will describe the photogrammetric apparatus, and present some preliminary results of photogrammetric analyses of rotor clouds in T-REX.