Assessment of ASCAT High Wind Assessment of ASCAT High Wind Retrievals within Extratropical Retrievals within Extratropical

Cyclones at NOAA Ocean Prediction Cyclones at NOAA Ocean Prediction CenterCenter

Khalil A. AhmadNOAA/NESDIS/StAR – Dell Perot Systems

Zorana Jelenak1, Joseph Sienkiewicz2, and Paul Chang1

1 NOAA/NESDIS/StAR2 NOAA/NWS/NCEP/OPC

2010 IEEE International Geoscience and Remote Sensing Symposiom25 - 30 July 2010

Honolulu, HI

NOAA Ocean Prediction CenterNOAA Ocean Prediction Center

• Issue marine warnings, forecasts, and guidance (text and graphical)

• Customers : commercial mariners, fishermen, recreational sailors, the USCG and the U.S. Navy.

• Mission: safety at sea, protection of life and property

• Warning Categories: GALE: 34 - 47 knots

STORM : 48 - 63 knots HURRICANE FORCE: > 64 knots

HF Extratropical Cyclone

Intense, non-tropical cyclones with hurricane force windsFeb 09, 2007, North Atlantic

kts

•Hurricane Force Warning Initiated Dec 2000 •Detection increased with:

-Forecaster familiarity-Data availability-Improved resolution -Improved algorithm

QuikSCAT Launch Jun 99

Hurricane Force Wind WarningInitiated Dec 00

25 km QuikSCATAvailable in N-AWIPS

Oct 01

12.5 km QuikSCATavailable May 04

Improved wind algorithm and rain flag Oct 06

TotalsA-289P-269558

WARNINGCATEGORIES

Pre- QSCAT1. GALE 34-47 kt1. GALE 34-47 kt2. STORM >48

QSCAT ERA1. GALE 34-47 kt1. GALE 34-47 kt2. STORM 48 -63 kt3. HURCN FORCE > 64 kt

HF Extratropical Cyclones Detection and Warning using QuikSCAT

• Fan-beam, C-band radar • V-pol antennas

• Non-continuous 1100 km (2 x 550 km with a 720 km gap) swath.

• Wind speed low bias at high winds • Wind products at 50 & 25 km horizontal resolutions.

ASCAT Fully Integrated into OPC ASCAT Fully Integrated into OPC operationsoperations

ASCAT vs. QuikSCAT Wind speeds ASCAT vs. QuikSCAT Wind speeds (Extratropical Cyclones)(Extratropical Cyclones)

Ope

ratio

nal A

SC

AT

QuikSCAT

ASCAT vs. QuikSCAT Wind speeds ASCAT vs. QuikSCAT Wind speeds (Extratropical Cyclones)(Extratropical Cyclones)

New

AS

CA

T

QuikSCAT

Operational ASCAT wind product detects STORM force wind. One wind warning category lower than the actual winds.

North Atlantic Extratropical Storm ExampleNorth Atlantic Extratropical Storm ExampleNew ASCAT Operational ASCAT

QuikSCAT

QuikSCAT & New ASCAT wind products detects HF wind.

kts

North Pacific Extratropical Storm ExampleNorth Pacific Extratropical Storm Example

QuikSCAT data reveals an area of HURRICANE force winds

Operational ASCAT wind product detects only GALE force wind. Two wind warning categories lower than the actual winds.

New ASCAT wind product detects STORM force wind. One warning category lower

New ASCAT Operational ASCAT

QuikSCAT

kts

North Pacific Extratropical Storm ExampleNorth Pacific Extratropical Storm Example

QuikSCAT data reveals an area of HURRICANE force winds

Operational GFS wind product detects only GALE force wind. Two wind warning categories lower than the actual winds.

New ASCAT wind product detects STORM force wind. One warning category lower

New ASCAT Operational GFS

QuikSCAT

kts

HF Extratropical Cyclone DatabaseHF Extratropical Cyclone Database

Surface AnalysisSurface Analysis

PAC011007 2007100712 43.93 -169.72 1013 LPAC011007 2007100718 43.23 -164.06 1010 GPAC011008 2007100800 42.37 -158.38 1010 GPAC011008 2007100806 41.33 -152.07 1007 GPAC011008 2007100812 39.87 -143.82 998 SPAC011008 2007100818 40.76 -137.83 974 SPAC011009 2007100900 43.15 -134.94 970 HPAC011009 2007100906 44.46 -134.08 964 HPAC011009 2007100912 46.45 -132.94 966 HPAC011009 2007100918 47.51 -132.81 968 HPAC011010 2007101000 48.90 -132.36 967 SPAC011010 2007101006 50.65 -132.3 964 SPAC011010 2007101012 52.17 -132.36 975 GPAC011010 2007101018 53.67 -131.68 977 G

Storm ID Date Lat Lon TypePres

Surface AnalysisSurface Analysis Storm trackStorm track

Hurricane Force ObservationsHurricane Force Observations( Oct’07 ~ May’08 )( Oct’07 ~ May’08 )

0

50

100

150

200

250

QS -12.5 km QS - 25 km AS - opr AS - new GFS OBS

212188

2 39 38 19

Read HF Cyclone Info. Extract QS & ASCAT Data &

Perform QC(land, ice, coast, rain) flags

Storm track database

Generate Mean Wind Fields

Storm motion

North

East

Estimate speed & Angle

(Heading Vector)

Generate Frequency of HF Occurrence per grid fields

5000km

5000

km

5000km

500

0km

Wind Field CompositeWind Field Composite

Mean Wind Speed Field Mean Wind Speed Field

Range rings -1000 km increments

kts

QuikSCAT Opr ASCAT

New ASCAT

Range rings -1000 km increments

Hurricane Force Wind Frequency Hurricane Force Wind Frequency

New ASCAT

Opr ASCATQuikSCAT

Range rings -1000 km increments

Storm Force Wind Frequency Storm Force Wind Frequency

QuikSCAT Opr ASCAT

New ASCAT

Range rings -1000 km increments

Gale Force Wind Frequency Gale Force Wind Frequency

QuikSCAT Opr ASCAT

New ASCAT

SummarySummary• ASCAT is the only data source of satellite OSVW operationally available to OPC forecasters after the loss of QuikSCAT

• Reliably retrieve low to moderate surface wind speeds• For higher wind speeds, operational ASCAT product retrievals have a low wind speed bias, which increases with increasing wind speed

• A new ASCAT GMF has been developed by NOAA / NESDIS to improve the high wind retrievals:

• High winds compare better to QuikSCAT retrievals (but still biased low)• Better detection of HF cyclones compared to operational ASCAT data product• Better representation of wind field Characteristics• QC flag needs tuning

• Reliance on an ASCAT- only data source, will degrade the OPC warning capability (specially for the dangerous HF extratropical cyclones)

• Reduced coverage due to nadir gap• Coarser resolution• Low wind speed bias

CFRSL GroupCFRSL Group

Backup SlidesBackup Slides

QuikSCATQuikSCATJun1999 ~ Nov 2009Jun1999 ~ Nov 2009

• Pencil-beam, Ku-band radar• H-pol & V-pol

• Continuous 1800-km data swath

• Large retrievable wind speed range • Sensitive to rain

• Two NRT data products at 25 km & 12.5 kmQuikSCAT mission ended on 23 Nov 2009

mid

fore

aft37°

52°

64°37°27°45°

90°135°64°

• Fan-beam, C-band radar • V-pol antennas

• Non-continuous 1100 km (2 x 550 km with a 720 km gap) swath.

• Wind speed low bias at high winds • Wind products at 50 & 25 km horizontal resolutions.

ASCATASCATOct 2006 ~ presentOct 2006 ~ present

GFS wind speed

Win

d sp

eed

erro

r

Operational ASCAT- QuikSCAT-GFS Operational ASCAT- QuikSCAT-GFS Wind SpeedsWind Speeds

OperationalASCAT

Sonde Wind Speed 28.8m/s

SFMR 28 m/s

ASCAT 22 m/s

New ASCAT

Sonde Wind Speed 28.8m/s

SFMR 28m/s

New ASCAT 25m/s

The nadir gaps increase the frequency at which ASCAT data do not sample or only partially sample weather systems of interest.

ASCAT QuikSCAT

QuikSCAT continuous swaths provide more coverage

ASCAT vs. QuikSCAT CoverageASCAT vs. QuikSCAT Coverage( Oct’07 ~ May’08 )( Oct’07 ~ May’08 )

ASCAT QC FlagASCAT QC Flag

New ASCAT QC flag needs tunning