The Observed Relationship Between GOES-16 Derived Overshooting Top Area and Midlevel Updraft Area

Abstract:

Recent idealized model studies have shown that the satellite-derived area of a thunderstorm overshooting top (OT) can be related to midlevel updraft area as well as provide a means to estimate tornado intensity. However, the relationship between OT area (OTA) and updraft area has not yet been documented in observations. Data collected during the RELAMPAGO field campaign in Argentina provide an excellent opportunity to explore these relationships. GOES-16 1-minute Mesoscale Domain Sector scanning captured several intense thunderstorms that were contemporaneously sampled by at least two Doppler on Wheels (DOW) radar. The ground-based radar network provides adequate sampling to retrieve 3D wind field from dual-Doppler radar scans every 3-4 minutes. Upon application of a recently developed approach (and variants) to GOES-16 infrared brightness temperature to calculate OTA, the radar-retrieved vertical velocities are used to quasi-simultaneously quantify updraft characteristics and OTA.

Three different RELAMPAGO cases are considered for this study: 10 November 2018, 12 November 2018, and 13 December 2018. These cases are comprised of multicellular and supercellular convective storms as well as a mesoscale convective system. During the 10 November 2018 supercell, the time histories of the OTA and the midlevel updraft area match well, with the peak OTA occurring at the same time as the peak in radar-determined midlevel updraft area, but the respective areal values at storm top (near 14 km) and midlevels (near 7 km) differ by nearly an order of magnitude. Simple models of buoyant thermals and plumes will be used to understand the relationship between the areas at these two levels. The other two cases will be examined to investigate whether this relationship is consistent in other modes of convection. The ultimate goal of this work is to develop a global dataset of satellite-derived updraft characteristics.