global turbulence nowcast and forecast system john k. williams, bob sharman, and cathy kessinger...
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Global Turbulence Nowcast and Forecast System
John K. Williams, Bob Sharman, and Cathy Kessinger (NCAR)
Wayne Feltz and Tony Wimmers (UW-Madison/CIMSS)
and UW-Madison SSEC/CIMSS
Briefing to FAA and Airline Industry Representatives
8 April 2010
ational Center for Atmospheric Research
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)
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 EXTWeb-based graphical display Cockpit uplink and display
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 stormenvironment
– Storm characterization from satellite data
• Cloud top heights• Overshooting tops
– Convection diagnosis (CDO) and nowcasts (CNO) based on model + satellite observations Source: P. Lester, “Turbulence – A new perspective for pilots,”
Jeppesen, 1994
CIT
Source: P. Lester, “Turbulence – A new perspective for pilots,” Jeppesen, 1994
CIT
MWT CAT
CIT
Global In situ Turbulence “Truth”United EDR above 10,000 ft MSL
07-01-2008 to 07-15-2008Delta EDR above 10,000 ft MSL
07-01-2008 to 10-31-2008
Ude, various airlines11-1-2008 to 11-10-2008
AIREPs, various airlines 11-1-2008 to 11-10-2008
Additional global turbulence measurements would be helpful….
Ellrod1
DTF3
FRNTGth
VWS
UBF
Ri
CLIMO
TEMPG
- NVA
NCSU1
NCSU2
EDRS10
GTG
CONUS GTG = Dynamic weighted fusion of multiple
turbulence diagnostics
0 h forecast valid 1500 UTC 22 September 2006
Model-based Turbulence Diagnostics
Operational GTG: http://adds.aviationweather.gov/turbulence/
Experimental GTG: http://weather.aero/turbulence
GFS-based diagnosticsRUC-based diagnostics
Ellrod indexFL350
EDR indexFL350
Ri fromthermal windFL200Note: breaks down at equator
Global CAT Diagnostics Based on GFS Model
6 hr forecast valid 18 UTC 4 Nov 2008
Global GTG Prototype (4-day loop)
Global GTG analyses 14-17 December 2007, ~35000 ft
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
14
12
10
8
6
4
150
200
300
400
500
600700
(~100 km)
subtropicalair mass
polar air mass
stratosphere
Pre
ssur
e (h
Pa)
Hei
ght
(km
)
tropopause
front
Tropopause folds with altitudesIllustration of tropopause fold mechanism
GLASH humidity with trop. folds
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”
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
Inferring CIT: Overshooting Tops
Overshooting Tops in AF 447 case
Frequency of turbulence vs. OT distance
Other Possible Satellite CIT Signatures
Rapid Convective Growth
Banded Cirrus Outflow
Rapid Anvil Expansion
CTOP
GCD
CClass
CTOP
GCD
CClass
CDO Interest Field(0-4 day, 0-3 night)
CDO Binary ProductThreshold = 2.5
GOES-East
(Lightning)
Interest Fields (0-1)
Convective Diagnosis Oceanic (CDO)
Global Turbulence and Convection
Global GTG – 12 hr Forecast
Global GTG – 12 hr ForecastConvective Diagnosis Oceanic
Global GTG – 12 hr ForecastConvective Diagnosis Oceanic
Pilot and InSitu Reports +90 min
• Goal: produce a comprehensive turbulence hazard product via empirical AI fusion of model and satellite-derived features
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
Vote: 1
=> 40 votes for “0”, 60 votes for “1”
Data pt.
Tree 1
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Data pt.
Tree 2
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Tree 3
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Tree 4
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Data pt.
Tree 100…
Statistical Evaluation: Moderate-or-greater turbulence (EDR ≥ 0.3 m2/3s-1)
• 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
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
Statistical evaluation: MoG turbulence Receiver Operating Characteristic Curves
GTG+model+satellite
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
Previous uplink demo of CONUS NTDA (in-cloud
turbulence) funded by FAA
2005-2007
/EXPERIMENTAL TURBULENCE FI UAL███/AN N███UA UPLINK-- 05 Sep 2006 21:38:13Z 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 | *MM | l lll M *MMM | lollo *lMl | oolo *l | oo * | * |080 * 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 | * SSSSSSMSS M | l S*SSSSSSSSSMSS M | lllS*SSSMSSSSSMSS l | lSMS*SMMMMSSSSMSS l | SSMM*MMMMMMMMMSS M | MM*SMMMMMMMMlllllMSS M | M*SSMMMMMMMMllllllMMM M | *MMMMMMMMMMMMMllllMMM | * MMlllMMMlMllllllMlll |040 * lllllllllllllllllMMllll | * llllllllllllllllS | * llllllllllMMS | * lllllllSSS | * lllllSSS | * lllMMS | * l llMM | * MM M | MM*MM oMSS | SM*MMMMM | MM *MM lMM | MMMSS S * l llM | MMMSSM * lllllll ol |l MMMM * lllllo | MMMMM * llllll | M * lllll | SSS * llllll | SSS M l * llll | SSS Mlllll *llM | MM lMlllll * l-------|---------valid-|--------X--------|-----------------90 +90|Left 40 2135Z (18 from 3819N/8058W) Right 40
Flight information
Legend
Route
Severe turbulence
Aircraft position
Waypoint
Vertical cross-section
Moderate turbulence
• Pilot registration and feedback via NCAR web page
• Pilot feedback mostly very positive
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
• 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
| | | |0|1|1|1|1|2|2|1|1|2|2|3|3|3|2|2|2|2|2|3|3|3|3|2|2|
Combining Turbulence and CTOP Uplink Products
Concept Version 1.2
• Planview + vertical cross section
• Cloud top height uplink– / = 30-40 kft– C > 40 kft
• Add global turbulence intensity as a vertical cross section
Combining Turbulence and CTOP Uplink Products
Concept Version 2.1
Acknowledgements
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
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.
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