The Effect of Latent Heat on the Extratropical Transition of Typhoon Sinlaku (2008)

1. The Effect of Latent Heat on the Extratropical Transition of Typhoon Sinlaku (2008) By: Michael Kevin Hernández

2. What is an extratropical transition (ET)? • Why is this important to study ETs? 2

3. What are the current problems in modeling & defining ETs? Problem: What is the sensitivity of ET onset and completion to latent heating from the storm and surrounding area? Hypothesis: The baroclinic processes alone would not suffice to initiate the ET of Typhoon Sinlaku. 3

4. Extratropical Cyclones Tropical Cyclones Most extratropical transitions (ET) of tropical cyclones (TC) re-intensify. The area of gale force winds may increase by a factor of 10. ~50% ~40% 100% Tropical Storm ~10% Other Dissipate (Hart & Evans 2001; Jones et al. 2003;Guishard 2006)

5. Extratropical Cyclones can cause loads of localized damage, e.g. 1996 Post-TC Hortense and 2007 Post-TC Noel. http://www.hurricanecity.com http://www.shunpiking.com http://www.hurricanecity.com

6. Absolute vorticity [10-5s-1] Even the smallest vortex can trigger and amplify downstream planetary waves. -2.0 -1.6 -1.2 -0.8 -0.4 0.0 0.4 0.8 1.2 1.6 2.0 2 1 0 -1 -2 Y [1000km] 0 5 10 15 20 x [1000km] (Riemer 2010)

7. Case study: Sept. 19 Sept. 20 Joint Typhoon Warning Center’s Best Track of Typhoon Sinlaku (2008) Sept. 21 Sept. 18 Sept. 17 Sept. 14 Sept. 12 Sept. 9 Sept. 7

8. ECMWF best track and model ensemble members of Sinlaku, but with perturbed initial conditions. latitude Sept. 2008 longitude

9. 72 hour forecast Small perturbations in the initial conditions lead to huge differences in the interaction of the cyclone and the trough. ensemble member 4 ensemble member 5 latitude ensemble member 8 ensemble member 10 ensemble member 9 ensemble member 21 longitude

10. 40 20 100 50 0 -50 Hart (2003) definition: Cyclone Phase Space on ECMWF analysis of Typhoon Sinlaku. 120 140 160 180 Baroclincity (B) ET completion ET onset 10 -300 -200 -100 0 100 200 300 Thermal wind at 900-600 hPa (-VLT)

11. Assuming Hart (2003) definitions of ET onset and completion, a 50 member ensemble forecast model still cannot pinpoint the ET process temporally. ECMWF 50 member ensemble for ET onset ECMWF 50 member ensemble for ET completion Sept. 13 Sept. 14 Sept. 15 Sept. 16 Sept. 17 Sept.18 Sept. 19 Sept. 20 Sept.21 Sept. 22

12. Klein et al. (2000) analysis Onset Japan Meteorological Agency There is no universal definition for ET onsetor completion. ECMWF analysis Joint Typhoon Warning Center Sept. 13 Sept. 14 Sept. 15 Sept. 16 Sept. 17 Sept.18 Sept. 19 Sept. 20 Sept.21 Sept. 22 ECMWF analysis Klein et al. (2000) analysis Completion Joint Typhoon Warning Center Japan Meteorological Agency

13. 18 Sept 1130 UTC CIRRUS EDGE Another method for the ET definition is defined by Klein et al. (2000), which uses satellite analysis. DRY SLOT DRY SLOT 19 Sept 1830 UTC 17 Sept 0930 UTC ET onset: 17 Sept 0800 UTC ET completion: 19 Sept 1800 UTC POSSIBLE WARMFRONTOGENESIS EYEWALL EROSION

14. What is the sensitivity of extratropical transition onset and completion to latent heating from the storm and surrounding area? Question: Hypothesis: The baroclinic processes alone would not suffice to initiate the extratropical transition of Typhoon Sinlaku.

15. WRF (ARW core) V3.0.1 model Physics (FULL) 9 km (outer) domain: Kain–Fritsch cumulus parameterization 3 km (inner) domain: convection is explicitly resolved Physics (Fake Dry Tropical Cyclone - FDTC) Same as FULL but: No cumulus parameterization on any domain Latent heating turned off in the microphysics Experiments:

16. We would want the domain to be from 15-65oN & 120-175oE latitude longitude

17. The ideal domain didn’t produce ideal results. latitude longitude

18. Moving the domain further south still meant that the trough was still in the domain. But not by much. latitude longitude

19. Now the boundaries are feeding a some information about the trough into the simulation. latitude longitude

20. There is a lot more information of the trough that is no longer explicit. latitude longitude

21. Feeding in the information of the entire trough isn’t producing ideal results either. latitude longitude

22. First (static) domain: • 740 × 430 points at 9 km horizontal resolution • centered at 33N and 150E • 36 vertical levels • Second (vortex following) domain: • 330 × 330 points at 3 km horizontal resolution • 36 vertical levels Domain size:

23. Varying the physics parameterizations, while keeping the northern boundary at 50oN, led to differences in TC track and intensity. JTWC Tracks

24. Latent heating affects whether the TC dies early, follows the best track, and the intensity of the storm. JTWC best track pressure Min pressure [hPa] Tracks over land

25. Deep layer mean (DLM) winds influence TC tracks and the DLM in each simulation varies: 900-200 hPa layer for FULL; 800-500 hPa layer for FDTC. While the JTWC best track is the arrow in black. FULL FDTC

26. 50o 40o 30o 20o FDTC FULL 17 Sept 1: The synoptic flow pattern at 700-200 hPa was influenced by a lack of latent heating. 50o 40o 30o 20o 50o 40o 30o 20o 18 Sept 19 Sept H H 120o 140o 160o 175o 120o 140o 160o 180o

27. FULL FDTC 50o 40o 30o 20o 50o 40o 30o 20o 50o 40o 30o 20o 19 Sept 2: The synoptic flow pattern at 700-200 hPa was influenced by a lack of latent heating. H H 20 Sept H H 21 Sept H H 120o 140o 160o 175o 120o 140o 160o 180o

28. 80 70 60 50 40 30 20 10 0 m2 S-2 area-2 FULL case: TC weakens (KE decrease) once the 500 hPa trough has passed by. Sept. 17 18 19 20 21 50o 40o 30o 20o H H H 120o 140o 160o 175o 120o 140o 160o 175o 120o 140o 160o 175o

29. 80 70 60 50 40 30 20 10 0 m2 S-2 area-2 FDTC case: TC weakens still (KE decreases) even as the 500 hPa trough has passed by. Sept. 17 18 19 50o 40o 30o 20o H H H 120o 140o 160o 175o 120o 140o 160o 175o 120o 140o 160o 175o

30. Near the end of the simulation First 6 hrs FULL warm frontogenesis The core of the storm within 6 hours and out between both simulations also are influenced by latent heat. strong core +78 hrs banding cold frontogenesis 20 Sept 12 UTC 17 Sept 06 UTC Near the end of the TC life +6 hrs 17 Sept 00 UTC weak core +30 hrs +6 hrs FDTC cold air seclusion 17 Sept 06 UTC 18 Sept 12 UTC

31. Tracks • Dynamically In summary, modeling ET of TC is hard even if we had a universal definition. • Temporally ECMWF 50 member ensemble for ET onset ECMWF 50 member ensemble for ET completion Sept. 13 Sept. 14 Sept. 15 Sept. 16 Sept. 17 Sept.18 Sept. 19 Sept. 20 Sept.21 Sept. 22 • Boundary placement • Choice of model physics

32. w/ latent heat w/o latent heat • Synoptics Latent heating is needed to maintain the TC and allow the TC to undergo ET. 21 Sept 19 Sept • KE • Inner core

33. Hypothesis: Confirmed • The baroclinic processes alone would not suffice to initiate the extratropical transition of Typhoon Sinlaku. • Two more new simulations: • 1) Remove TC with FULL Physics • 2) Remove TC with FDTC Physics Future work: Questions? • FDTC simulation suggests an opportunity to explore the evolution of the 500 hPa trough in the absence of TC and Latent Heating.

34. Supplementary slides

35. JTWC Varying the physics parameterizations, while keeping the northern boundary at 50oN, led to differences in TC track and intensity. track differences

36. WRF (ARW core) V3.0.1 • Physics (FULL) • WSM 5 class microphysics • Goddard SW radiation • RRT LW radiation • 5-layer thermal diffusion Land-surface • MYJ PBL • ETA Surface Model • KF Cumulus parameterization • turned off for domains with resolution exceeding 5 km • Physics (FDTC) • Same as FULL but • No cumulus parameterization • Latent heating turned off in the microphysics Model Configurations:

37. Z = h How I calculated the Deep layer mean (DLM) winds. FULL FDTC weighted average … Z = 0