High Impact Weather PANDOWAE Description of the ET of Super Typhoon Choi-Wan (2009) based on the YOTC-dataset ¹, D. Anwender¹, S. C. Jones2, J. Keller2, L. Scheck¹ 2 ¹Karlsruhe Institute of Technology, German Weather Service (DWD) INSTITUTE FOR METEOROLOGY AND CLIMATE RESEARCH Source: NASA KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.edu
Motivation How do numerical weather prediction systems represent convection within a tropical cyclone? Are there features in moisture and temperature tendencies that are characteristic of different stages of a TC's lifecycle? How do model tendencies evolve during a TC's lifecycle? 2
Dataset new dataset at ECMWF available: YOTC-data three-hourly model tendencies of temperature, specific humidity and horizontal wind components tendencies are provided as set of 3-dimensional physical process fields containing the individual parts of the absolute tendencies Dynamics (grid-scale) Cloud scheme (grid-scale) Convection scheme (subgrid-scale) Turbulent diffusion Radiation Sub-grid orography Source: ECMWF 3 evaluation of YOTC-data during lifecycle of Super Typhoon Choi-Wan (2009) in a student's seminar at KIT
Super Typhoon Choi-Wan Category 5-Typhoon, lowest pressure: 915 mb, maximum winds: 195 km/h (10-minute sustained), 260 km/h (1-minute sustained) Source: NOAA-IBTrACS Choi-Wan Source: NOAA-IBTrACS Source: NOAA-IBTrACS SST [ C] 4 12/09 14/09 16/09 18/09 20/09
Super Typhoon Choi-Wan Category 5-Typhoon, lowest pressure: 915 mb, maximum winds: 195 km/h (10-minute sustained), 260 km/h (1-minute sustained) Source: NOAA-IBTrACS Choi-Wan Source: NOAA-IBTrACS Source: NOAA-IBTrACS SST [ C] 5 12/09 14/09 16/09 18/09 20/09 ET
Synoptic overview contours: geopotential at 850 hpa, shaded: rel. Vorticity at 200 hpa, vectors: wind at 200 hpa 18/09, 00UTC 19/09, 00UTC 20/09, 00UTC 21/09, 00UTC 22/09, 00UTC 23/09, 00UTC ζ [10-4 1/s] 6
Methodology calculation of specific humidity and potential temperature budgets during weakening phase (storm relative, assumption of balanced budgets) tendency equation for specific humidity: q v qv v = v h v TC h q Q q ; t p v con cld Qq =Q diff + Q + Q q q q v v v v tendency equation for potential temperature: v = v h v TC h Q ; t p diff con cld rad Q =Q Q Q Q contributions to the tendencies are from: horizontal and vertical advection, turbulent diffusion (diff), radiation (rad), subgrid-scale convection scheme (con) and the grid-scale cloud scheme (cld) 7
Methodology tendency terms areal averaged in a box of 10 x 10 (20 x 20 during extratropical stage) centered on location of minimum pressure of Choi-wan temporal average 12 UTC 00 UTC, i.e. during the first twelve hours after initialization time 8
Moisture and potential temperature budgets pressure [hpa] on 16/09 12 UTC 17/09 00 UTC [K/h] 9 [g/(kg*h)] turbulent diffusion compensates convection scheme in boundary layer from mid- to upper troposphere: vertical advection compensates convection scheme dipole structure in cloud scheme weak horizontal advection and weak total tendencies
Moisture and potential temperature budgets pressure [hpa] on 19/09 12 UTC 20/09 00 UTC [K/h] 10 [g/(kg*h)] turbulent diffusion compensates convection scheme in boundary layer in mid- and upper troposphere: vertical advection compensates cloud scheme dipole structure in cloud scheme horizontal advection leads to negative tendencies
Moisture and potential temperature budgets pressure [hpa] on 21/09 12 UTC 22/09 00 UTC EX-Choi-wan [K/h] 11 [g/(kg*h)] temperature tendencies: net cooling in middle- and upper-troposphere due to radiation and horizontal advection temperature tendencies: vertical advection and cloud scheme compensate in middle- and upper-troposphere strong convection scheme above boundary layer due to cumulus clouds in cold sector
Moisture and potential temperature budgets pressure [hpa] on 21/09 12 UTC 22/09 00 UTC EX-Choi-wan [K/h] 12 [g/(kg*h)] moisture tendencies: strongest tendencies at lower troposphere, horizontal advection and convection scheme compensate turbulent diffusion and cloud scheme moisture tendencies: cloud scheme and vertical advection compensate in middle- and upper-troposhere
Moisture budgets at different stages pressure [hpa] EX-Choi-wan [g/(kg*h)] 13 [g/(kg*h)] [g/(kg*h)]
Interaction between Choi-Wan and Frontal Wave contours: rel. vorticity at 850 hpa, shaded: rel. vorticity at 200 hpa (left); 2m Temperature (right) 19/09, 12UTC 19/09, 12UTC FW FW TC TC ζ [10-4 1/s] 20/09, 18UTC T_2m [K] 20/09, 18UTC FW Ex-TC ζ [10-4 1/s] 14 T_2m [K]
Interaction between Choi-Wan and Frontal Wave strong advection of warm air masses into the region of the frontal wave strong advection is compensated by vertical motion intensification of frontal wave as extratropical low cloud scheme dominant in mid- and upper troposphere 20/09, 18UTC 19/09, 12UTC 20/09, 18UTC FW Ex-TC ζ [10-4 1/s] 15 T_2m [K]
Downstream Impact of Choi-Wan and Frontal Wave 19/09, 00UTC ζ [10-4 1/s] - + 16 assessment of downstream impact by calculation of eddy kinetic energy budget (Session 9, J. Keller) baroclinic conversion in the region of frontal wave flux of eddy kinetic energy into the jet downstream of the frontal wave frontal wave strengthens jet and wave pattern prior to Choi-Wan's ET
Downstream Impact of Choi-Wan and Frontal Wave 21/09, 00UTC ζ [10-4 1/s] -+ + 17 strong baroclinic conversion where extratropical low develops out of Choiwan flux of eddy kinetic energy into the jet and the midlatitude wave pattern radiation of eddy kinetic energy into downstream trough where extratropical low development begins
Conclusions & Future Work 18 in the boundary layer of Typhoon Choi-Wan turbulent diffusion and the subgrid scale convection scheme compensate each other in tropical stage of Choi-Wan the convection and cloud scheme, and vertical advection are most important contributors to tendencies above boundary layer during transformation stage of ET dynamics are the most important contributors to temperature and moisture tendencies tendencies in the extratropical low that developed out of Choi-Wan are a lot weaker than in the tropical cyclone
Conclusions & Future Work 19 warm air advection into the region of the Frontal Wave might have favoured the extratropical development frontal wave strengthened midlatitude jet and wave pattern prior to Choi-Wan's ET in a region of baroclinic conversion from potential to kinetic energy and therefore potentially favoured its extratropical development flux of eddy kinetic energy into regions downstream of Choi-Wan where an extratropical low developed look at YOTC-data for several other TCs compare analysis of tendencies with forecast of tendencies
Thanks for your attention INSTITUTE FOR METEOROLOGY AND CLIMATE RESEARCH Source: NRL KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.edu