Exploring dense optical flow-retrieved winds for characterization of convective phenomena and future applications
Presented by: Dr. Theodore McHardy
Date: August 20, 2024 12:00 am
Location: In-person in the CIRA Commons (Coffee and light refreshments provided just prior to the presentation)
Modern optical flow techniques have recently been used to retrieve cloud-top motion around convective updrafts and to compute divergent flow using visible satellite imagery. This study applies these novel methods to multiple convective phenomena, including a supercell thunderstorm, a tropical cyclone, a volcanic eruption, and multiple pyrocumulonimbus (pyroCb) events. Optical-flow-retrieved wind vectors and cloud-top divergence (CTD) are compared in order to provide quantitative context and test the baseline functionality of optical-flow-retrieved parameters as investigative tools for all types of deep convection. Multiple time steps between images, representing the different scan modes of the sensor, are tested as inputs for determining the feasibility of using imager scans with larger spatial coverage, such as full hemispheric view. Emphasis is placed on pyroCb events, which are increasingly recognized for impacts spanning the upper-troposphere to stratosphere, including perturbations in chemistry, cloud nucleation, and climate circulation. CTD captures updraft intensification, as well as differences in convective activity between two pyroCb events and individual updraft pulses occurring within a single event. Optical flow-derived parameters can uniquely provide a top-down analysis of convective phenomena, including individual pyroCbs, in real-time. These wind-retrieval techniques show potential for wide-ranging research and operations applications, such as characterizing pyroCb smoke source inputs for downstream smoke modeling, cloud/aerosol height assignment, data assimilation, or tropical cyclone intensification studies.