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

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Tree 1

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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.