An Observational Evaluation of RKW Theory over the U.S. Southern Great Plains

Details

• Journal Title:
  Journal of the Atmospheric Sciences
• Personal Author:
  Kirshbaum, Daniel J. ; Sindhu, Kapil Dev ; Turner, David D.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; GSL (Global Systems Laboratory)
• Description:
  The theory of Rotunno et al. (“RKW” theory) addresses the behavior of squall-line cold pools in vertically sheared flows. It predicts that, within a given thermodynamic environment, a balance between baroclinic vorticity generation by the cold pool and low-level environmental vertical wind shear induces an upright updraft along the gust front that maximizes the initiation of new convective cells. Although this theory has been evaluated numerically, its applicability to observed systems remains unclear and is limited by a lack of critical measurements, including high-frequency thermodynamic and wind profiles across the gust front. Herein, observations from the Atmospheric Radiation Measurement Southern Great Plains (ARM-SGP) observatory near Lamont, Oklahoma, are used to evaluate RKW theory for 10 well-observed squall lines over a 11-yr period. For this evaluation, RKW parameters including cold-pool intensity (c), low-level ambient, line-normal vertical shear (ΔVn), subcloud and cloud-layer updraft tilts, and multiple measures of system intensity are estimated. The c estimates rely on thermodynamic retrievals from the Atmosphere Emitted Radiance Interferometer (AERI), which are uncertain but verify reasonably well against independent observations. As predicted by the theory, for c/ΔVn ≥ 1, c/ΔVn correlates positively with updraft tilt and negatively with system intensity, but these results are not always statistically significant and are also sensitive to the method by which ΔVn is evaluated. Specifically, ΔVn evaluations that extend above the cold-pool top yield greater consistency with RKW predictions. Also, some measures of intensity correlate more strongly with standard moist instability metrics than with RKW parameters.
• Source:
  Journal of the Atmospheric Sciences, 82(7), 1341-1360
• DOI:
  https://doi.org/10.1175/JAS-D-24-0185.1
• ISSN:
  0022-4928 ; 1520-0469
• Format:
  PDF
• Publisher:
  American Meteorological Society
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:a846cd6d67dccb5913750873d54f73493987a117880a44c6b6986564e5c4a47fe23818cfc54d06ed17b483067c8f7cf02754eef63c74c91714c10560dd347acd
• Download URL:
  https://repository.library.noaa.gov/view/noaa/71045/noaa_71045_DS1.pdf
• File Type:
  [PDF - 10.67 MB ]