AOSC Seminar by Dr. Steve Koch, 10/13/2022
AOSC Seminar
Dr. Steve Koch
University of Arizona
Title: A Review of Mesoscale Gravity Waves and their relation to Spontaneous Balance Adjustment and Deep Convection
Abstract:
Gravity waves are ubiquitous entities in the atmosphere, being generated by topography, wind shear, latent heating, and flow imbalance associated with jets and fronts. Many of these waves display short wavelengths and have little bearing on the weather; however, mesoscale gravity waves (MGW), which have been found to be closely related to the existence of dynamical imbalance, can create coherent precipitation bands composed of ice pellets with lightning, blizzard conditions, or lines of severe convective storms. The MGW sub-class of highly nonlinear waves can create damaging surface winds, disrupt aviation, and drive rapid changes of water level in both coastal and inland water bodies. These large-amplitude waves wreak havoc on local weather forecasts, being largely unanticipated and misunderstood.
Following a short review on the basics of gravity wave dynamics and terminology, this talk will emphasize the nature and diagnosis of unbalanced components of the mass and momentum adjustments leading to MGW generation and the importance this has on high-impact weather. It will be shown that MGW genesis is favored as a jet streak propagates away from the upper-level trough axis and toward the inflection axis between the trough and downstream ridge, especially when the horizontal wavelength between this trough and ridge shortens with time, and the jet streak separates from its geostrophic component at the base of the trough and propagates toward the ridge. This evolution is favored when a synoptic cyclone and associated jet streak develop rapidly, especially when accompanied by latent heating. Increasing separation between the geostrophic wind maximum and the actual jet streak is related to intensifying upper-level flow imbalance commonly associated with strong tropopause folding events, and leads to the repeated development of spontaneous, continuous emission of MGWs. Convective latent heat release not only increases the flow imbalance, but it helps to maintain ducted MGWs, producing even greater imbalance and consequential increase of MGW emission – essentially, a positive feedback process.
Bio:
Education
University of Wisconsin – Madison Meteorology B.S., 1972
University of Wisconsin – Madison Meteorology M.S., 1974
University of Oklahoma – Norman Meteorology Ph.D., 1979
Employment and Distinguished Appointments
2021– Research Professor and Instructor, University of Arizona
2019– Adjunct Professor, Embry-Riddle Aeronautical University
2013–23 Affiliate Professor, University of Oklahoma
2011–19 Director, National Severe Storms Laboratory (retired)
2009–11 Adjunct External Examiner, North Carolina A&T University
2006–11 Director, Global Systems Division, NOAA/OAR/Earth Systems Research Lab
2004–11 Deputy Director, NOAA/NCAR Developmental Testbed Center
2000–05 Chief, Forecast Research Division, NOAA/OAR/Forecast Systems Laboratory
1993–00 Associate Professor (tenured), North Carolina State University
1980–93 Meteorologist, Lab for Atmospheres, NASA/Goddard Space Flight Center
Selected Honors, Distinctions, and Awards
Citations of refereed journal papers: 5,450, h-Index: 40 (as of 12 Sept 2022)
(based on Google Scholar Citation)
2019 Albert Nelson Marquis Lifetime Achievement honoree
2015 National Weather Association Larry R. Johnson Award recognizing extraordinary accomplishments which significantly contributed to operational meteorology
2008 Fellow, American Meteorological Society
1998 National Weather Association Research Achievement Award
1998 National Weather Service Award for Applied Research
1991 NASA/Goddard SFC Exceptional Achievement Award
Selected Community Service (since 2010)
2021 – Editorial board member of MDPI journal Meteorology
2021 – Copy Editor, Advances in Atmospheric Science, Institute of Atmospheric Physics, Chinese Academy of Sciences
2015–18 NOAA VORTEX-SE Program Manager and Executive Committee Chair
2015–17 Member, NOAA Storm Surge Roadmap Executive Steering Committee
2013–16 Member, Executive Committee, AMS Commission on Weather and Climate Enterprise Forecast Improvement Group
2012– Fellow, Cooperative Institute for Mesoscale Meteorological Studies (CIMMS)
2012: Executive Committee Chair for Weather Ready Nation Birmingham workshop
2012: NSF Review Panel for National Center for Atmospheric Research
2012–18 External Advisory Panel, OU Center for Analysis and Prediction of Storms
2011–16 External Advisory Committee, NCAR Earth Observing Laboratory
Contact: Louis Uccellini
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AOSC Seminar
Pre-seminar refreshment: N/A
Seminar: 3:30-4:30pm, Room: ATL 2400(only when in-person)
Meet-the-Speaker: 4:30-5:00pm, Room: ATL 3400(only when in-person) [For AOSC Students only]
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