1. Global Turbulence Nowcast and Forecast System
John K. Williams, Bob Sharman, and Cathy Kessinger (NCAR) Wayne Feltz and Tony Wimmers (UW-Madison/CIMSS)
Briefing to FAA and Airline Industry Representatives
8 April 2010
ational Center for Atmospheric Research
and UW-Madison SSEC/CIMSS

2. Motivation
Unexpected turbulence continues to cause passenger and crew injuries and aircraft damage
Sparse flights, few weather observations and limited communications limit information available to pilots on oceanic routes
Current World Area Forecast System (WAFS) operational products have inadequate accuracy, temporal and spatial resolution
Large SIGMET areas may be difficult to circumnavigate
Ellrod index
Does not capture all turbulence mechanisms
Doesn’t explicitly address convective turbulence
Probabilistic hazard assessment is needed
WAFS international SIGMETs (4-hr updates)
SIGWX facsimile chart (6-hr updates)

3. Global Turbulence DSS Goals
Extend U.S. FAA/NWS “Graphical Turbulence Guidance” to global domain for World Area Forecast System (WAFS)
Provide statistical and deterministic hazard assessment
Data fusion to address all major known turb. mechanisms
Gridded 1/3 horizontal resolution, 10,000 – 45,000 ft
Tactical turbulence and convection nowcasts (0-3 hours) for avoidance/ mitigation
Strategic turbulence forecasts (3-36 hours) for planning and route selection SM
LGT
MOD
SEV
EXT
Web-based graphical display
Cockpit uplink and display

4. Global Turbulence Data Fusion: Sources
Clear-air turbulence (CAT)
Global Forecast System (GFS) model-derived “diagnostics”
“Tropopause fold” identification from model and satellite data
Mountain-wave turbulence (MWT)
Model winds and terrain data
Satellite gravity wave identification and features
Downslope wind conditions
Convectively-induced turbulence (CIT)
Model fields related to clouds/storms and storm environment
Storm characterization from satellite data
Cloud top heights
Overshooting tops
Convection diagnosis (CDO) and nowcasts (CNO) based on model + satellite observations
MWT
CAT
CIT

5. Global In situ Turbulence “Truth”
United EDR above 10,000 ft MSL to
Delta EDR above 10,000 ft MSL to
Ude, various airlines to
AIREPs, various airlines to
Additional global turbulence measurements would be helpful….

6. 0 h forecast valid 1500 UTC 22 September 2006
Model-based Turbulence Diagnostics
Ellrod1
DTF3
FRNTGth
VWS
UBF Ri
CLIMO
TEMPG
- NVA
NCSU1
NCSU2
EDRS10
CONUS GTG = Dynamic weighted fusion of multiple turbulence diagnostics
GTG
0 h forecast valid 1500 UTC 22 September 2006
Operational GTG:
Experimental GTG:

7. Global CAT Diagnostics Based on GFS Model
Ellrod index
FL350
EDR index
FL350
Ri from
thermal wind
FL200
Note: breaks down at equator
6 hr forecast valid 18 UTC 4 Nov 2008
RUC-based diagnostics
GFS-based diagnostics

8. Global GTG Prototype (4-day loop)
Global GTG analyses December 2007, ~35000 ft

9. Tropopause Fold Diagnosis
TF a source of CAT
Identified via gradients in satellite water vapor channel along with GFS model data
Verified with Aqua Ozone Mapping Instrument
GLASH humidity with trop. folds 14 12 10 8 6 4
150
200
300
400
500
600
700
(~100 km)
subtropical
air mass
polar air mass
stratosphere
Pressure (hPa)
Height (km)
tropopause
front
Illustration of tropopause fold mechanism
Tropopause folds with altitudes

10. Mountain-Wave Turbulence
Diagnostics from low-level winds and terrain
Working on algorithm to identify presence, interference of gravity waves from satellite water vapor channel
NWP data may help distinguish conditions under which wave breaking/turbulence is likely
MODIS 1-km 6.7 m, 6 March 2004
Experimental “wave interference scale”

11. Convectively-induced Turbulence (CIT)
CIT can be patchy (few km) and dynamic (few minutes)
Some mechanisms are known
Shears caused by updrafts, downdrafts, anvil outflow
Gravity waves produced by overshooting tops
Diagnose using data fusion of observations, nowcasts + NWP models
Simulation: Cloud (blue), turbulence (red) Courtesy of Dr. Todd Lane

12. Inferring CIT: Overshooting Tops
Overshooting Tops in AF 447 case
Frequency of turbulence vs. OT distance

13. Other Possible Satellite CIT Signatures
Rapid Anvil Expansion
Banded Cirrus Outflow
Rapid Convective Growth

14. Convective Diagnosis Oceanic (CDO)
(Lightning)
GOES-East
CTOP
CTOP
CClass
CClass
GCD
GCD
CDO Binary Product
Threshold = 2.5
CDO Interest Field
(0-4 day, 0-3 night)
Interest Fields (0-1)

15. Global Turbulence and Convection
Global GTG – 12 hr Forecast
Convective Diagnosis Oceanic
Pilot and InSitu Reports +90 min
Global GTG – 12 hr Forecast
Convective Diagnosis Oceanic
Global GTG – 12 hr Forecast
Goal: produce a comprehensive turbulence hazard product via empirical AI fusion of model and satellite-derived features

16. Statistical Data Fusion Methodology
Random Forest (RF): A non-linear data mining technique used to analyze retrospective data and create a non-parametric (makes no assumptions about functional form), probabilistic empirical predictive model via an ensemble of decision trees
Data pt.
Data pt.
Data pt.
Data pt.
Data pt.
Tree 1
Tree 2
Tree 3
Tree 4
Tree 100 …
Vote: 1
Vote: 0
Vote: 0
Vote: 1
Vote: 0
=> 40 votes for “0”, 60 votes for “1” 16

17. Statistical Evaluation: Moderate-or-greater turbulence (EDR ≥ 0
Statistical Evaluation: Moderate-or-greater turbulence (EDR ≥ 0.3 m2/3s-1)
RF Inputs
MaxCSI
MaxTSS
AUC
GTG diagnostics
0.10
0.79
0.96
GTG+model
0.12
0.82
0.97
GTG+model +satellite
0.13
0.87
0.98
Based on June 27 – August 23, 2007, GOES-E and RUC-13, United in situ peak EDR as truth, alt.  10 kft
Note that adding model and satellite fields substantially improves nowcast skill

18. Statistical evaluation: MoG turbulence Receiver Operating Characteristic Curves
GTG+model+satellite

19. Schedule
Initial Global Turbulence nowcast prototype with CIT and CAT running this summer
Oceanic uplink demonstration of customized text messages planned with United Airlines
Other participants welcome if no major system changes required

20. Vertical cross-section
Flight information
Previous uplink demo of CONUS NTDA (in-cloud turbulence) funded by FAA
/EXPERIMENTAL TURBULENCE FI UAL███/AN N███UA UPLINK
-- 05 Sep :38:13Z FL 300 orient. 83 deg
'+'=waypoint, '*'=route, 'X'=aircraft at 38.3N, 80.6W
' '=no_data, 'o'=smooth, 'l'=light, 'M'=mod, 'S'=severe
(52 to IAD)
| *
MM | *
MM | l lll M *
MMM | lollo *
lMl | oolo *
l | oo *
| *
| *
M |llllllll ll *
MM |lllllllllllllll l *
lll |lllllllllollllllll *
MMl l |MMllllllllooollllll *
MMl l |MMMl lllllllllollll *
MM l |MMMM llll llol ll *
MM | MMMM ll *
MMS | MMM *
MSS | MM *
MSS +PUTTZ
MSS | * SSSSSS
MSS M | l S*SSSSSSSSS
MSS M | lllS*SSSMSSSSS
MSS l | lSMS*SMMMMSSSS
MSS l | SSMM*MMMMMMMM
MSS M | MM*SMMMMMMMMlllll
MSS M | M*SSMMMMMMMMllllll
MMM M | *MMMMMMMMMMMMMllll
MMM | * MMlllMMMlMllllllM
lll | * lllllllllllllllllMMl
lll | * llllllllllllll
llS | * llllllllll
MMS | * lllllll
SSS | * lllll
SSS | * lll
MMS | * l ll
MM | *
MM M | MM*MM o
MSS | SM*MM
MMM | MM *MM l
MM | MMMSS S * l l
lM | MMMSSM * lllllll o
l |l MMMM * lllllo
| MMMMM * llllll
| M * lllll
| SSS * llll
ll | SSS M l * l
lll | SSS Mlllll *
llM | MM lMlllll * l
| valid-| X |
|Left Z (18 from 3819N/8058W) Right 40
Legend
Route
Waypoint
Severe turbulence
Pilot registration and feedback via NCAR web page
Pilot feedback mostly very positive
Moderate turbulence
Aircraft position
Vertical cross-section

21. Combining Turbulence and CTOP Uplink Products Concept Version 1.1
Planview
Derived from global turbulence product
O = null
L = light
M = moderate
S = severe
Use lower case letters when in-cloud; upper case for out-of-cloud

22. Combining Turbulence and CTOP Uplink Products Concept Version 1.2| 0| 1| 2| 3|
Combining Turbulence and CTOP Uplink Products Concept Version 1.2
Planview + vert. cross section
Derived from global turbulence product
O = null
L = light
M = moderate
S = severe
Use lower case letters when in-cloud; upper case for out-of-cloud
Add maximum cloud top height as a vertical cross section
0 = 25-30kft
1 = 30-35kft
2 = 35-40kft
3 = >40kft

23. Combining Turbulence and CTOP Uplink Products Concept Version 2.1
Planview + vertical cross section
Cloud top height uplink
/ = kft
C > 40 kft
Add global turbulence intensity as a vertical cross section

24. Acknowledgements Collaborators include
This research is supported by NASA, primarily under Grant No. NNX08AL89G. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Aeronautics and Space Administration.
Collaborators include
Jenny Abernethy, Gary Blackburn, Huaqing Cai, Jason Craig, Bill Hall, David Johnson, Frank McDonough, Dan Megenhardt, Greg Meymaris, Nancy Rehak, Matthias Steiner, and Stan Trier at NCAR
Michael Donovan and Earle Williams at MIT Lincoln Laboratory
Richard Bankert and Jeffrey Hawkins at Naval Research Laboratory-Monterey
Todd Lane at University of Melbourne