The Impact of the Extratropical Transition of Typhoon Dale (1996) on the Early 1996-97 Wintertime Stratospheric Circulation Andrea L. Lang 1, Jason M. Cordeira 2, Lance F. Bosart 1 and Daniel Keyser 1 1 Deptartment of Atmospheric and Environmental Sciences, University at Albany, SUNY 2 NOAA/ESRL/Physical Sciences Division 4 th International Workshop on Extratropical Transition of Tropical Cyclones 24 May 2012 Mont Gabriel Lodge, Quebec
Motivation Western North Pacific tropical cyclones (TCs) may: recurve into the midlatitudes transport heat and moisture poleward undergo extratropical transition (ET) interact with North Pacific jet stream (NPJ) produce Rossby wave train amplification and dispersion TC extratropical flow interaction The impact of ET on the downstream flow: An idealized modeling study with a straight jet: +120 h +240 h jet streak TC ex TC 325 335 345 355 365 375 K Plotted: 2-PVU θ (shaded) and wind speed (thick contours every 5 m s 1 starting at 45 m s 1 ), and SLP (dash contours every 5 hpa at/below 1000 hpa). Figure adapted from Riemer et al. (2008).
Motivation Western North Pacific tropical cyclones (TCs) may: recurve into the midlatitudes transport heat and moisture poleward undergo extratropical transition (ET) interact with North Pacific jet stream (NPJ) produce Rossby wave train amplification and dispersion TC extratropical flow interaction Rossby wave train amplification can result in ridge amplification potential development into a blocking high (BH) BHs are associated with meridional eddy heat and momentum fluxes - via the EP flux, BHs can be associated with eddy-mean flow interaction and wave propagation from the troposphere into the stratosphere Troposphere stratosphere interaction e.g. Martius et al. (2009), Orsolini et al. (2009) & Nishii et al. (2010, 2011)
Background Eliassen-Palm (EP) flux is a useful way to measure eddy-mean flow interaction from a zonal mean perspective Zonal mean eddy momentum flux Zonal mean eddy heat flux EP flux vector (F ) In the absence of diabatic effects (D): EP flux convergence Measure of the net rate of transfer of wave activity (A) from one latitude or height to another McIntyre (1976)
Background EP flux Wave Activity convergence divergence increase decrease Zonal mean westerlies decrease increase P cooling du dt < 0 warming Eddy impacts: Zonal mean flow & temperature (via induced residual circulation) EQ du dt > 0 Pole When F (p) is upward: Tropospheric Rossby waves can impact the stratospheric jet and temperature structure
Zonal average heat flux > 0 F (p) is strongly upward Background When is F (p) maxed in the upward direction? Planetary wave Synoptic wave (e.g. BH) EP flux into stratosphere is maximized in the mid-latitudes when a large-scale synoptic ridge constructively interferes with a background planetary ridge BH over a climatological planetary wave ridge (trough) can amplify (suppress) the upward wave flux from troposphere to stratosphere Troposphere stratosphere interaction e.g. Martius et al. (2009), Orsolini et al. (2009) & Nishii et al. (2010, 2011)
November Climatology (30 yr) 100 hpa φ (m) and Zonal Mean φ Anomaly (m) Geographic Dependence Orsolini et al. (2009) & Nishii et al. (2010, 2011) 1. BH in Atlantic sector Amplify upward EP flux Warming polar stratosphere 2. BH in W Pac/Far East Suppressed upward EP flux Cooling polar stratosphere 3. BH over Alaska/E Pac Case dependent Case Analysis: Can a recurving TC that results in an amplified ridge impact the upward wave flux in this region?
Case Study: Supertyphoon Dale (1996) 0600 UTC 17 Nov SLP of 943 hpa 1800 UTC 12 Nov TC extratropical flow interaction 0600 UTC 11 Nov Recurvature 1200 UTC 13 Nov Extratropical Transition
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time ±0 h 1800 UTC 12 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +12 h 0600 UTC 13 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +24 h 1800 UTC 13 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +36 h 0600 UTC 14 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +48 h 1800 UTC 14 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +60 h 0600 UTC 15 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +72 h 1800 UTC 15 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +84 h 0600 UTC 16 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +96 h 1800 UTC 16 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +108 h 0600 UTC 17 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time +120 h 1800 UTC 17 Nov Dale 280 290 300 310 320 330 340 350 360 370 380 K NCEP CFSR Dynamic tropopause (DT = 2 PVU surface) potential temperature (K; shaded), DT wind speed (m s 1 ; black), and 850-hPa cyclonic relative vorticity (10 5 s 1 ; yellow)
SUPERTYPHOON DALE (1996) FLOW RESPONSE Interaction time ±0 h 1800 UTC 12 Nov Interaction time +120 h 1800 UTC 17 Nov Recurvature, TC NPJ interaction, and ET of Dale resulted in major reconfiguration of tropospheric flow over North Pacific and North America
Tropospheric NH A Z and NH K E for 1996 relative to climatology NH K E and A Z (10 6 J m 2 ) 6.0 5.0 4.0 3.0 2.0 1.4 1.2 1.0 0.8 0.6 0.4 NH A Z Dale NH K E 3.0 J F M A M J J A S O N D +3.0 SD +2.0 +1.0 ±0.0 1.0 2.0 Climatology values from 1979 2008 NCEP NCAR Reanalysis NH: 20 85 N 1000 hpa to 100 hpa
The stratospheric signature of Dale
Departure from Climatology: Zonal Mean Temperature Anomaly -45 Warm Polar Lower Stratosphere +24 Dale 10 October 1996 28 February 1997 at 80 N (every 3 K) 1 Nov 96 1 Dec 96 1 Jan 97 1 Feb 97 1 Mar 97
7 Day Average Ending: 6 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 9 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 12 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 15 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) EP flux convergence in the stratosphere after Dale 10 mb latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 18 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) EP flux convergence in the stratosphere after Dale 10 mb Ridge latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 21 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) EP flux convergence in the stratosphere after Dale 10 mb Ridge latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 24 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) EP flux convergence in the stratosphere after Dale 10 mb Ridge latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 27 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) EP flux convergence in the stratosphere after Dale 10 mb Ridge latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 30 Nov 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb Ridge latitude 70 mb Ridge 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 3 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 6 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 9 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 12 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 15 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 18 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 21 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 24 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 27 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) Horizontal EP flux divergence couplet - stratospheric recovery 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
7 Day Average Ending: 30 Dec 1996 EP Flux (m 2 s -2 ) and EP flux convergence (m s -2 ) 10 mb latitude 70 mb 80 N Zonal Mean Temperature Anomaly (K) 1 Nov 96 Dale 1 Dec 96 1 Jan 97 1 Feb 97 400 mb
Departure from Climatology: Zonal Mean Temperature Anomaly -45 +24 Upward EP flux associated with Dale Dale 10 October 1996 28 February 1997 at 80 N (every 3 K) 1 Nov 96 1 Dec 96 1 Jan 97 1 Feb 97 1 Mar 97
Departure from Climatology: Zonal Mean Zonal Wind Anomaly -27 +30 Dale 10 October 1996 28 February 1997 at 65 N (every 3 m s -1 ) 1 Nov 96 1 Dec 96 1 Jan 97 1 Feb 97 1 Mar 97
Summary 1800 UTC 17 Nov TC Dale (1996) was associated with high amplitude ridging and the development of a BH after it underwent extra-tropical transition Dale ridge The Dale ridge was in phase with background planetary wave ridge, resulting in: upward EP flux EP flux convergence in the stratosphere pressure 7 day average ending: 21 Nov 1996 latitude
Summary Result: Weaker zonal mean westerlies in the stratosphere Occurred during the climatological spin up period of the stratospheric polar night jet Result: Warmer potential temperature in lower/midstratosphere Corresponded to weak stratospheric thermal wind Stratospheric recovery on the order of 30-45 days Small/strong vortex during mid-winter 1996-97
Future Work: Via the memory of the stratosphere, what type of late fall/early winter events impact mid and late winter circulation? AO Index 20 Sept 1996 to 15 Mar 1997