Elisa Murillo - October 6

Weather and Climate Systems

Environmental and Storm Characteristics Associated with Warm and Cold Above-Anvil Cirrus Plumes

Elisa Murillo

Wednesday, October 6

3:00pm

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Above-anvil cirrus plumes (AACPs) in midlatitude convection serve as important indicators for severe storms and stratospheric hydration events. Recent studies of AACPs have illustrated large variability in their characteristics, with many of the causes still unknown. In particular, some AACPs appear equally as cold (or colder) than the broader storm top when compared to the more frequently observed warm feature, the enhanced-V signature, in infrared (IR) satellite imagery. To confidently identify the presence of an AACP, trained experts utilize visible imagery as the primary source of AACP identification and IR imagery for further confirmation. AACPs that occur after sunset no longer have visible imagery are therefore left unidentified.

We identify 89 warm and 89 cold AACPs with 1-minute GOES-16 satellite imagery coupled with ground-based radar observations and reanalysis data to answer the following research questions: 1) Why do some AACPs exhibit a warm feature in IR imagery while others do not? and 2) What observable storm and environment differences exist between warm and cold AACPs? Our initial hypothesis stated that cold AACPs formed in double-tropopause regions and/or were too optically thin for their brightness temperature to be observed by IR imagery. We first match all manually identified AACPs to their corresponding radar-based storm tracks. We then examine their storm characteristics and near-storm environment using both a tropopause-relative and absolute height framework for temperature and moisture vertical profiles, echo-top heights, storm-relative winds, levels of maximum detrainment (LMDs), and severe storm reports. Results indicate that cold AACPs tend to occur in tropical environments, featuring higher, cold-point tropopauses. Conversely, warm AACPs tend to occur more in mid-latitude environments, with lower tropopauses accompanied by an isothermal region (or tropopause inversion layer).