The Operational Impact of QuikSCAT Winds at the NOAA Ocean Prediction Center Joe Sienkiewicz NOAA Ocean Prediction CenterJoan Von Ahn STG/NESDIS ORAOutlineOPC overviewImpact Warnings and FeaturesHurricane Force WindsSST impacts on near surface windsSummary and Recommendations

OPC ResponsibilityWind Warning CategoriesGALE 34-47 knotsForce 8/9STORM 48-63 knotsForce 10/11HURRICANE FORCE - 64 knots and greater Force 12

Wind speed (knots)

Warning ImpactPercent Change in Short-Term Warning Decisions by OPCTimelinesaddedAdditionaltrainingForecaster queryForecaster input onlyInterpreted forecaster comments

Chart2

3022

75

54

1010

Atlantic

Pacific

Period of Study

Percent Increase

Sheet1

AtlanticPacific

Fall 20023022

Spring 200375

Fall 200354

Winter 20041010

Sheet1

00

00

00

00

Atlantic

Pacific

Period of Study

Percent Increase

Sheet2

Sheet3

Winter 2004 (Feb 15 to Mar 15)When QuikSCAT was available, changes were made to:68 % of the events in the Atlantic 50% of the events in the PacificEvent- Lows, Highs and Wind areas (speed and aerial extent)Atlantic

Pacific

Hurricane Force WindsQuikSCAT able to distinguish between STORM and HURRICANE FORCE winds

OOCL AmericaM/V Explorer

OOCL AmericaPacific - Jan 2000350 containers lost overboard 217 crushed or bent out of usable condition.

Vessel lost power for a short periodand took several severe rolls.

Hurricane Force CyclonesWhat have we learned?Winter events October through March (April)Most frequent Atlantic (January); Pacific (December)Minimum SLP (avg. 965 to 970 hPa) Minimum SLP - larger range in AtlanticExplosive deepeners Western portion of basins (most frequent); preferred tracksShort lived (less than 24 hours) (avg. lifecycle 5 days)Shallow warm core seclusionWind max S to SW of lowMost difficult to forecast at day 4 forecast time over North PacificLess than 10 % forecast 4 days in advance!! Number of HF Cyclones observed

Period of StudyAtlanticPacific2001-200222152002-200323222003-20041522

Composite of maximum winds (knots)Pacific (11 cyclones) Atlantic (5 cyclones) Composite of QuikSCAT winds for 11 North Pacific and 5 North Atlantic HF storms. This plot shows the distribution of maximum winds as observed by QuikSCAT for all cyclones in the composite. HF winds are Red, Storm -Yellow and Gale Green. HF FORCESTORMGALE

SST Impacts on Near Surface Winds

12.5 km QuikSCAT3-day GOES SST Composite

25 km QuikSCATWind speed difference (GFS 10m-QuikSCAT)

GFS 10 WInds12.5 km QuikSCAT

Bias corrected 10m Winds Wind speed difference (knots) (GFS 10m-QuikSCAT)

Eta 10m GFS 10m

GFS 9950 Sigma

30 day avg. diff11/05/04Model Winds - QSCATVery Unstable PBL975-skin < -4

30 day avg. diffModel Winds - QSCAT Very Stable PBL 975-skin > 4Eta 10m GFS 10m

GFS 1st Sigma

Eta 10m GFS 10m

GFS 1st Sigma

SST impacts on Wind Field

Due to QuikSCAT OPC forecasters are more conscious of underlying SST on near surface winds

(always knew an impact but forecasters can now see it)

Forecaster toolsmodel soundingsstability indicesmix of 1st sigma and 10m windswind speed difference fields

QuikSCAT Rain QuandryJanuary 4, 2005

12.5 km QuikSCATSSM/I Wind Speeds

25 km QuikSCAT SSM/I Rain Rate

12.5 km QuikSCATQuikSCAT Ambiguities

25 km QuikSCAT SSM/I Rain RateThere are times when our forecasters do not know what to believe!

SummaryImpact - Significant Cultural change to ocean analysis and forecasting within OPC10 % Wind Warnings determined by QuikSCATAssessment of features more accurateAbility to assess initial numerical model conditions

Can differentiate between significant and extreme winds Storm versus Hurricane Force Significance of PBL stability on near surface winds

QuikSCAT winds have changed the way we do business

Precip QuandryAt times just do not know impact on wind retrievals

Recommendations(for future instruments)

Large swath width Independent rain measurement Ability to quantify impact of rain Large retrievable wind range (0 to Hurricane Force) 12.5 km resolution or better Reduced land mask (less than 30 km) Minimum 4 looks per day per ocean (from operational platforms) Data access near-real time (1 to 1.5 hour delivery after acquisitionno more) Available in forecaster workstations in comprehensive form

These two composites show the maximum observed wind speed for each 25 km spaced grid point. The south semicircle is clearly the area preferred to observe HF winds. The cases contributing to these composites consisted of open ocean examples well away from the influence of land. There do appear to be some differences between the composites with a strong hint of a well displaced occluded frontal structure in the Atlantic composite with a large area devoid of storm winds. There also is a hint of maybe two different scales in the Atlantic composite with a minima of winds (sub Gale) to the west of the center. The Pacific composite suggest a more compact wind field with storm force fairly close into the center to the north. We may indeed be seeing the evidence of inherent differences between the evolution of Pacific vs. Atlantic extreme storms. The Pacific jet structure seems to favor diffluent jets and left front quadrant developments. This favors Norwegian type cyclones that may indeed had a smaller inner core. The Atlantic cyclone composite wind field is significantly more spread out with a very clear signal of a Shapiro Keyser frontal structure. The inner radius of inner winds are displaced about 120 nm to the south of the center. The pacific inner core are only about 60 nm or less from the cyclone center. Just food for thoughtmakes you wonder if scale is working against us and may indeed be the contributing factor to the difficulty of the models being able to forecast the Pacific cyclones frequently.