1 James D. Doyle 1, Hao Jin 2, Clark Amerault 1, and Carolyn Reynolds 1 1 Naval Research Laboratory, Monterey, CA 2 SAIC, Monterey, CA James D. Doyle 1, Hao Jin 2, Clark Amerault 1, and Carolyn Reynolds 1 1 Naval Research Laboratory, Monterey, CA 2 SAIC, Monterey, CA NRL Mesoscale Model Adaptive Observing during T-PARC/TCS08 Global-model adjoint tools (mostly dry) have been applied to TC track Adjoints have not been applied to TC genesis systematically -Forecasts of genesis are often poor (e.g., T-PARC/TCS08) Is targeting for TC genesis feasible (T-PARC/TCS08)? Global-model adjoint tools (mostly dry) have been applied to TC track Adjoints have not been applied to TC genesis systematically -Forecasts of genesis are often poor (e.g., T-PARC/TCS08) Is targeting for TC genesis feasible (T-PARC/TCS08)?

2 COAMPS Adjoint Sensitivity J: response function x i :state vector at initial time t i x t :state vector at final time t f M T :adjoint of non-linear model, M Sensitivity of the response function at final time t f to the initial (or model forecast) state at time t i Adjoint-Based “Optimal” Perturbations w j :weighting parameter s:scaling parameter (u max ~1 m s -1 ) Adjoint Allows for the Mathematically Rigorous Calculation of Forecast Sensitivity COAMPS ® Nonlinear, Adjoint, Tangent Linear Model Setup  x=40 km, 18 h (18 h lead time) (real time 24 h with 24, 36, 48-h lead times)  x=10 km, 9 h (15 h lead time) (not shown here) PBL, Surface Flux, Microphysics (no ice) J: Kinetic Energy in a Box (lowest 1 km) Adjoint Sensitivity for 14 West Pacific Genesis Events (5 Super Typhoons) Fitow, Man-Yi, Krosa, Sepat, Trami, Wipha, Yutu (Pre- T-PARC/TCS08) Nuri, Sinlaku, Hagupit, Jangmi, Higos, TCS025, 16W (T-PARC/TCS08)

3 COAMPS Forecasts during T-PARC / TCS-08 Real-Time COAMPS Adjoint for Targeting Guidance. 40 km resolution for 24-h, 36-h, 48-h lead times. Adaptive response function box. Real-Time COAMPS-TC 72-h Forecasts with Moving Meshes. 45/15/5 km horizontal resolution. Adjoint Sensitivity C130 Flight Track COAMPS radar reflectivity every 30 minutes on 5 km moving grid COAMPS Track (red) & Official Warning Positions (black) (12 h) Jangmi

4 Nonlinear Model Evolution Tropical Cyclone Fitow (Pre- T-PARC) Nonlinear Model Evolution Tropical Cyclone Fitow (Pre- T-PARC) 18-h 10-m Winds & SLP (0-h Adjoint) 1000 mb 1004 mb Response Function Area Response Function Area Nonlinear model captures monsoon gyre and asymmetric structure  Adjoint sensitivity computed during early development phase (18-36 h) 36-h 10-m Winds & SLP (18-h Adjoint) Asymmetric structure 18-h adjoint sensitivity (06Z Z 30 Aug ‘07) > 35 kts Best Track

5 Sensitivity Fields Moisture & Potential Temperature Sensitivity Fields Moisture & Potential Temperature 36-h KE sensitivity to 18-h state Banded Sensitivity Structures  KE/  (4 km)  KE/  q v 500 m  KE/  q v  KE/  Low-Level Moisture Sensitivity Mid-Level  Sensitivity  e Perturbation WEWEWE Low-Level  e Maximum (Destabilization) Preferred regions of large sensitivity to low-level moisture and . Low-level  e optimal perturbations: destabilize & saturate core.

TLM Optimal U’ at 500 m 18h (re-scaled at 3h ) 10-m Wind Speed Pert. 23 m s -1 U max =39 m s -1 Rapid Growth Eye Structure Tangent Linear u’ at 500 m 24 m s -1 Evolved Adjoint-Based Perturbations Perturbation Winds Evolved Adjoint-Based Perturbations Perturbation Winds correlation ~ 0.5 Evolved 18 h Nonlinear u’ at 500 m 24 m s -1 Evolved perturbations in TLM and NLM are well correlated. Rapid growth over 18 h: U sfc =23 m s -1, p sfc =-8 hPa,

7 T-PARC/TCS08 Real-Time Adjoint Forecasts TC Sinlaku T-PARC/TCS08 Real-Time Adjoint Forecasts TC Sinlaku 54-h KE sensitivity to 36-h state Vorticity sensitivity bands that are anticyclonically curved. Strongest sensitivity to low- and mid-level  and q v. C130 sampled key portions of the sensitivity. 24-h adjoint sensitivity 36-h lead time Valid at 12Z 10 Sep km vorticity sensitivityTotal energy sensitivity C130 Flight Track C130 Flight Track Dropsondes Best Track

8 T-PARC/TCS08 Real-Time Adjoint Forecasts TC Jangmi T-PARC/TCS08 Real-Time Adjoint Forecasts TC Jangmi 54-h KE sensitivity to 36-h state Vorticity sensitivity shows a wave packet pattern. The  and q v sensitivity have multiple maxima over a broad area. C130 sampled only a small portion of the sensitivity. 24-h adjoint sensitivity 36-h lead time Valid at 00Z 25 Sep km vorticity sensitivityTotal energy sensitivity Best Track

9 T-PARC/TCS08 Real-Time Adjoint Forecasts TC Jangmi T-PARC/TCS08 Real-Time Adjoint Forecasts TC Jangmi 54-h KE sensitivity to 36-h state SST sensitivities were computed in real time. The SST sensitivity often showed complex patterns. C130 deployed many AXBTs during T-PARC/TCS08. SST Valid at 00Z 25 Sep 2008Surface temperature (SST) sensitivity L L

10 Genesis Sensitivity Fields TC Nuri (T-PARC/TCS08) Genesis Sensitivity Fields TC Nuri (T-PARC/TCS08) 36-h KE sensitivity to 18-h state  KE/  (0.5 km) & SLP (18 h) Vortex Structure Evolved Optimal U’ (18-36 h) 12 m s -1 Rapid Growth Eye Structure 18-h adjoint sensitivity (06Z 15 Aug - 00Z 16 Aug 2008) Low-Level  e Max. Tilted Against Shear  KE/  e (18 h) W E Large sensitivity to radial vorticity gradient. The q v and  sensitivities are 3-4x greater than u sensitivity. Optimal  e perturbations destabilize & saturate core.

11 Perturbation Energy Characteristics Summary of 16 Cases (13 Events) Perturbation Energy Characteristics Summary of 16 Cases (13 Events) Initial Perturbation Domain Average of Optimal Perturbations Evolved in TLM Initial total energy maximum in low-levels (bottom up). Deep perturbation growth throughout troposphere. Non-developers show weakest growth. Final Perturbation (18 h) Upper-Level Max. Consistent With Background Deep Response Function Box is Consistent

12 Conclusions Adjoint sensitivity characteristics for TC genesis & intensification. -Low-level maxima suggestive of bottom-up progression. -Preferred regions of moistening, destabilization, & vorticity bands. -Broad SST sensitivity regions linked to convection. -TL approximation is accurate for TCs considered (with moisture). Predictability of tropical cyclogenesis. -Low predictability (500-m winds: 50% cases show > 10x growth 18 h -1 ). -Sensitivity structures (particularly q v and  ) may be observable. Future Directions -Higher resolution sensitivity calculations. -Data denial and targeting experiments based on T-PARC / TCS08.

13 Genesis Sensitivity Fields TC025 (Non-Developer) Genesis Sensitivity Fields TC025 (Non-Developer) 36-h KE sensitivity to 18-h state Non-developers show slow growth, weaker sensitivity to q v and . Greater sensitivity to vertical shear.  KE/  (0.5 km) & SLP (18 h) No Vortex Structure Evolved Optimal U’ (18-36 h) 3 m s -1 Slow Growth 4x Slower than Nuri 4x Weaker than Nuri  KE/  e (18 h) WE WE Sensitive to Shear  KE/  u (18 h)

14 Dry and Moist Sensitivity Comparison Gradients and Evolved Perturbations Dry and Moist Sensitivity Comparison Gradients and Evolved Perturbations  KE/  u 5 km 6.9x10 -3 m s -1 Moist  KE/  u 5 km -3.1x10 -4 m s -1 Dry Moist shows faster growth (>10x) and smaller scale than dry adjoint. Dry processes organize large-scale, moist processes dominate growth. Evolved p’ sfc -8 hPa -5 hPa SLP Min. Moist -0.3 hPa Evolved p’ sfc Dry

15 SST Sensitivity Fields Tropical Cyclones Fitow and Wipha SST Sensitivity Fields Tropical Cyclones Fitow and Wipha 36-h KE sensitivity to 18-h state Fitow Wipha  KE/  SST Sensitivity of 36-h KE to 18-h SST Sensitivity to SST maximum near TC core & along track (asymmetry). SST perturbations over 18 h (1°C max.) suggest pre-WISHE stage. -Fitow:-0.75 hPa and +1.0 m s -1. -Wipha:-0.50 hPa and +1.2 m s -1.

16 Sensitivity of Adjoint Results to Resolution Tropical Cyclone Fitow (  x=10 km) Sensitivity of Adjoint Results to Resolution Tropical Cyclone Fitow (  x=10 km) q v perturbation (0-3 km) and SLP (15 h)  KE/  (8 km) & SLP (15 h) Increase in horizontal resolution from 40 km to 10 km yields similar sensitivity structures and relationships. Sensitivity to moistening and warming in low-levels. Banded vorticity sensitivity structures. Evolved perturbations: winds~42 m s -1 (9 h), SLP ~ -8 hPa (9 h) Banded Sensitivity Structures Correlated  and q v Perturbations  perturbation (0-3 km)

17 NOGAPS COAMPS (Dry dx=100 km) NOGAPS COAMPS 48 h Total Energy / SLP SV: Initial SV: Final Evolved Perturbations Initial Sensitivity Doyle, Amerault, Reynolds NOGAPS SVs and COAMPS Adjoint Comparison Tropical Cyclone Fitow NOGAPS SVs and COAMPS Adjoint Comparison Tropical Cyclone Fitow