PPT-The Influence of an Upper Tropospheric Potential Vorticity Anomaly on Rapid Tropical Cyclogenesis

Michael S Fischer and Brian H Tang Motivation Nearly half of all Atlantic genesis events form in an environment characterized by upper tropospheric forcing for ascent McTaggart Cowan et al 2013. geog-www.sbs.ohio-state.edu/courses/G620/.../ASP620Lecture10.ppt. . Cyclogenesis. Extratropical cyclones often form when an . upper level trough (e.g. a shortwave) . approaches . a front that is stationary or moving relatively slowly. Lesson 6: Potential . vorticity. Potential . Vorticity. Concept of potential . vorticity. :. Take a column of air defined by two potential temperature surfaces (. θ. and . θ. +. Δθ. ). . Move this column of air eastward. Force it to go up and over a mountain range.. 1979–2010). ~3 STCs/year. Strong TT . Weak TT . Trough induced . N = 105. STC Climatology (. 1979–2010). N = 34. Strong TT . Weak TT . Trough induced . STC Climatology (. 1979–2010). N = 56. Strong TT . cyclogenesis. (bombs. ). textbook section 8.5. definition. :. . SLP deepening rate . . 24 . mb. / 24 hours. . is known as 1 “. bergeron. ” . (Sanders and . Gyakum. 1980). example: 18 Feb 2004, off the US East Coast. Tropopause. . Atmos. 5110/6110. Synoptic–Dynamic Meteorology I. Jim Steenburgh. University of Utah. Jim.Steenburgh@utah.edu. Supplemental Reading: . Lackmann. (2011) Chapter 4. What is PV Thinking?. geog-www.sbs.ohio-state.edu/courses/G620/.../ASP620Lecture10.ppt. . Cyclogenesis. Extratropical cyclones often form when an . upper level trough (e.g. a shortwave) . approaches . a front that is stationary or moving relatively slowly. reporter : Lin . Ching. Based on . Dunkerton, T. J., M. T. Montgomery, and Z. Wang, 2009: Tropical . cyclogenesis. in a tropical wave critical layer: Easterly waves. . Atmos. Chem. Phys.. , . 9. , 5587–5646.. Diabatic. Energy. . Sources. Baroclinic. Energy Sources. Adapted from Fig. 9 in . Beven. (2012). 30. th. Conference on Hurricanes and Tropical Meteorology. TCs. Subtropical cyclones. Frontal cyclones. satellite data using CCD. Klaus-Peter Heue. 1. , Melanie Coldewey-Egbers. 1. , Andy Delcloo. 2. ,. . Christophe Lerot. 3. , Diego Loyola. 1. , Pieter Valks. 1. , Michel van Roozendael. 3. , . Elpida. By Rick . Garuckas. and Andrew . Calvi. Role of Mid-latitude Cyclones. Reduce temperature gradients/. baroclinicity. .. Convert potential energy to kinetic energy . . 1. Although these processes bring the atmosphere closer to a balanced state, a perfectly balanced state is never achieved. . Tropical . Cyclone . Lifecycle. http://glossary.ametsoc.org/wiki/Tropical_cyclone. . http://glossary.ametsoc.org/wiki/Tropical_cyclone. . TC Lifecycle Stages & Characteristics. Key structural features. Suzana J. Camargo,. Mingfang. Ting and . Yochanan. . Kushnir. LDEO, Columbia University. GloDecH. Meeting, OCP, LDEO, December 14, 2011.. Atlantic PDI . (power dissipation index ~. . V. 3. max. ) . Energy. . Sources. Baroclinic. Energy Sources. Adapted from Fig. 9 in . Beven. (2012). 30. th. Conference on Hurricanes and Tropical Meteorology. TCs. Subtropical cyclones. Frontal cyclones. Davis (2010) methodology:. Massachusetts Institute of Technology. Two Points of View. Macroscopic. : What sets the frequency of tropical cyclones on the planet? Are tropical cyclones agents in a system that maintains itself in some critical state?.