1 The Operational Impact of and Future Requirements for Satellite Ocean Surface Vector Winds in Tropical Cyclone Analysis Michael Brennan 1, Richard Knabb 1, Paul Chang 2, Joseph Sienkiewicz 3, Zorana Jelenak 2, Kevin Schrab 4 1 NOAA/NWS/NCEP/NHC, 2 NOAA/NESDIS/STAR, 3 NOAA/NWS/NCEP/OPC, 4 NOAA/NWS/OST 61 st Interdepartmental Hurricane Conference 6 March 2007

2 Impact of OSVW Data on TC Analysis and Forecasting QuikSCAT data available in operational workstations at NHC since 2000 Some information on TC intensity, especially for tropical storms, but not major hurricanes –Limited by instrument resolution –Interpretation complicated by rain contamination Improved detection/tracking of TC centers for analysis and model initialization Often only source of outer wind radii information for open ocean systems  affects watch/warning areas

3 Use of QuikSCAT at NHC Based on 2003–2006 Tropical Cyclone Discussions Does not account for instances where QSCAT used but not explicitly mentioned in TCD

4 NOAA OSVW Requirements Workshop 5–7 June 2006 – NHC, Miami, FL Goals 1.Summarize utility and impact of currently available satellite OSVW data in operational weather forecasting 2.Define NOAA’s operational OSVW requirements 3.Explore sensor/mission concepts using proven remote sensing technologies to meet these requirements

5 Who Else is Using OSVW? Workshop Participants NHC, CPHC, JTWC –TC analysis and forecasting NWS Ocean Prediction Center, NHC’s Tropical Analysis and Forecast Branch (TAFB), NWS coastal WFOs, DoD –Marine forecasts, warnings, and analyses –Identification of hurricane force extratropical cyclones at OPC NOAA/NESDIS – Develop retrieval algorithms, data processing, real time data distribution NCEP/Environmental Modeling Center, FNMOC, ECMWF –Data assimilation for NWP modeling NASA/JPL Academic and research communities Private sector marine forecasters, recreational mariners

6 Operational Requirements All-weather retrievalsAll-weather retrievals –Accurate retrievals in rain Accuracy levied upon 10-m 1- min sustained wind –Speed: +/- 2 kt in 0–165 kt wind range –Direction: +/- 10° (2 σ) (10 – 165 kt) +/- 20° (2 σ) (4 – 10 kt) Revisit time: 6 h (1–3 h goal) –Interval between measurements at particular point on ocean surface Helene 23 September 2006

7 Operational Requirements Reduce time from measurement to product availability (product latency) to 45–60 min –15 min goal 2.5 km x 2.5 km spacing between unique wind vector retrievals (1 km goal) Retrievals within 2.5 km of coast (1 km goal) Data delivered into operational workstations (N-AWIPS/AWIPS) and data assimilation systems Product documentation/tutorials/training

8 13km resolution Max wspd kts Rms 5.71 kts Available Today! 2km resolution Max wspd kts rms 2.14 kts Definitely Achievable 35km resolution Max wspd kts rms 8.88 kts 70km resolution Max wspd 91.0 kts rms kts Likely range of NPOESS solution Instrument Resolution Affects Ability to Measure Maximum Wind (Max retrievable wind speed does not account for rain effects) 1km resolution Max wspd kts True Wind Field User Requested 25km resolution Max wspd kts rms 7.72 kts Available Today!

9 Current and Future OSVW Missions AMI/ERS-2 Seawinds/QuikSCAT WINDSAT CMIS/NPOESS-C In orbitApproved Planned foreign missions Unknown instrument designs Research missions Questionable data availability (no agreements in place to share data) SeaWINDS/ADEOS-II 895 km1700 km 500 km 1600 km 2 x 550 km w/ 768-km nadir gap ~60% of QuikSCAT coverage X No CMIS on NPOESS C-1 A less capable CMIS-successor is planned beginning with C-2 in China - HY-2 India - OceanSat-2 ? ASCAT/METOP – 3-satellite series

10 Next Generation Ocean Vector Wind Mission (XOVWM) Recommended to NOAA by National Academies’ Decadal Survey advanceXOVWM combines available technology and measurement heritage  represents order of magnitude advance in scientific and operational capability with moderate risk and cost –Ku-band scatterometer (high resolution) –C-band scatterometer (less sensitivity to rain) –Multi-frequency polarimetric radiometer (provide rain corrections) Meeting revisit time requirements (6 h) would require at least 2, and probably 3 satellites

11 Key Recommendations Interagency Strategic Research Plan for Tropical Cyclones: The Way Ahead, February 2007 –“Due to the importance of OSVW data—for use by tropical cyclone forecasters and in tropical cyclone NWP systems—the JAG/TCR strongly endorses the development and acquisition of a capability to meet the OSVW observation requirements. This capability is absolutely critical to meeting the operational needs of the tropical cyclone forecast and warning centers…” Sixth WMO International Workshop on Tropical Cyclones (IWTC-VI), San José, Costa Rica, November 2006 –“IWTC-VI recommends that the WMO Space Program strongly endorse the specific recommendations of the US National Oceanic and Atmospheric Administration Operational Satellite Ocean Surface Wind Vector Winds Requirements Workshop Report….” Majority Report, NOAA Science Advisory Board Hurricane Intensity Research Working Group, 8 October 2006 –“Combining a broad range of atmospheric and oceanic observing techniques provides the best overall observing capacity. The current mix of satellites, manned aircraft, buoys, radar, etc, should be maintained as a critical component of the overall hurricane forecasting process.”

12 Summary Currently available operational OSVW data have led to significant improvements in TC analysis and forecasting –Advances in marine analyses, forecasts, and warnings from high seas to coastal waters NOAA has no plans to launch an operational OSVW mission to maintain current data quality after QuikSCAT –Cannot afford take step backward and lose improvements made! High-quality OSVW data critical to addressing hurricane intensity problem –Analysis tool for inner core structure for model input and validation of model output

13 Summary OSVW data from NPOESS MIS likely of limited utility for TC analysis –Based on experience with WindSat at NHC –Resolution not sufficient for TC analysis needs, maybe no wind direction? Future international research missions –Availability and quality of data unknown Place XOVWM on accelerated timetable –Minimize post-QuikSCAT gap in high-quality OSVW data –Some of cost could be defrayed by limiting the ocean vector winds capabilities of MIS

14 Goals for Continued use of OSVW Data in Operations Short termShort term –Push QuikSCAT capabilities to limits –Attempt to improve WindSat retrievals –Expedite data processing, distribution, and training for ASCAT Mid TermMid Term –Maintain operational availability of QuikSCAT data through instrument life span beyond FY09 –FY09 – Study and design of XOVWM mission (sensor, satellite bus and ground system) Long TermLong Term –FY10–12 – procurement, integration, and testing of XOVWM –FY13 – XOVWM mission launch and calibration/validation ASCAT Coverage (courtesy COMET/EUMETSAT) QuikSCAT launch (courtesy NASA)

15 Activity since NOAA Workshop July 2006 –Attended NASA Ocean Vector Winds Science Team meeting August 2006 –Workshop report finalized and distributed September 2006 –Briefed the Technical Director for the Oceanographer of the Navy October 2006 –Briefed NWS Director Johnson –Attended NPOESS Polar Max meeting November 2006 –Briefed NOAA CFO and Program Analysis and Evaluation Director December 2006 –Presentations given at AGU Fall Meeting and NOAA Hurricane Conference –Interactions with NASA about next generation OSVW mission January 2007 –Briefed Vice Admiral Lautenbacher –Presentation given at AMS Annual Meeting February 2007 –Briefed NOAA Observing Systems Council

16 Feedback from DoD DoD support for XOVWM would bolster efforts to move toward NOAA’s operational requirements and limit post-QuikSCAT data gap Reference IHC Action Item #2: “Satellite Ocean Surface Vector Winds Operational Impacts and Requirements” – Thursday Informal meeting in the hall after this session

17 Additional Slides

18 ASCAT Coverage QuikSCAT pass over Katrina What ASCAT Coverage would look like 550 km swath 700 km gap

19 WindSat in TCs – Preliminary Evaluation WindSat in TCs – Preliminary Evaluation WindSat not able to retrieve hurricane force winds in raining conditions with current algorithm –Limited by ~50 km resolution Current wind vector solution not suitable for TC center fixing –Difficultly closing off circulations – broad wind shift often seen instead of well-defined center –37GHz imagery better suited, other frequencies and polarizations being evaluated

20 Other Future OSVW Missions NPOESSNPOESS –Conical Microwave Imager/Sounder (CMIS) cancelled –Replacement passive instrument (MIS) being reconfigured –1.2–1.8 m dish size will limit resolution Resolution similar to or worse than WindSat (50 km) Wind direction may be tradable quantity –Earliest MIS will fly is 2016 on NPOESS/C2 India/ChinaIndia/China –Each planning scatterometry mission –Design uncertain –No agreement to share data

21 ASCAT Courtesy EUMETSAT Courtesy COMET/EUMETSAT

22 Comparison of IORD II requirements and QuikSCAT and WindSat performance IORD-II Threshold QuikSCATWindSat IORD-II Objective NEW SVW Requirements Horizontal Cell Size20km 25km12km 50km operational 1km 2.5km x2.5km unique grid spacing 1kmx1km goal operational 5km experimental 35km experimental Mapping Uncertainty5km1km Measurement Range 6-50kts 0-360° 6-75kts 0-360º 6-50kts 0-360º 6-95kts 0-360º 0-165kts 0-360º Measurement Accuracy Speed Greater of 4kts or 10% ~2.3kts Greater of 1.9kts or 10% All wspd +/-1.9kts Direction Wspd>10kts ~20º Wspd 20º Wspd>15kts <20º ~10º wspd >10kts ~10º Wspd<10kts ~ 25º Wspd >6kts <20º Wspd<15kts <30º ~10º Wspd<10kts ~20º Latency90min3h5h15min 45-60min 15min goal Revisit Time6h18h34h1h6h (1-3h goal) Swath Width1700km1800km1000km Coastal Winds 30/20km of the coast 75km of the coast 2.5km of the coast IORD-II Threshold Better than IORD-II ThresholdWorse than IORD-II Threshold IORD-II Objective Better than IORD-II ObjectiveWorse than IORD-II Objective

23 OSVW Measurements Currently Available Provided by NASA QuikSCAT Accuracy of ocean surface wind speed and direction –Speed: ~2 kt from 6 – 75 kt –Direction: ~ 20° for winds > 6 kt Operational 25-km and 12.5-km retrievals Retrievals within 20 km of coast 1800-km wide measurement swath ~ 3 h from data measurement to display on operational workstations ~18 h between measurements at a given point on the ocean surface –Time between measurements over a TC can be much longer due to wide swath gaps at low latitudes

24WindSat Launched on Coriolis satellite January 2003 – retrievals available at NHC since June 2006 –900-km wide data swath –~50-km resolution of wind retrievals First attempt to retrieve wind vector with passive sensor Unable to retrieve hurricane force winds in raining conditions with current algorithm Current wind vector solution not suitable for TC center fixing

25 QuikSCAT Ku-band scatterometer Designed for 5-yr life span, now in 8 th year On backup transmitter (primary failed July 2006) Orbit maneuvers not necessary through 2009 Instrument healthy and should continue to operate for several more years NASA funding data acquisition/processing through 2009 Courtesy NASA

26 Other Current OSVW Instruments WindSat Passive RadiometerWindSat Passive Radiometer –Launched January 2003 as risk reduction mission for NPOESS CMIS –First attempt to retrieve wind vector with passive sensor 50-km resolution wind retrievals –Unable to retrieve hurricane force winds in raining conditions with current algorithm –Wind vector solution not suitable for TC center fixing based on NHC evaluation ASCAT ScatterometerASCAT Scatterometer –Onboard METOP-A satellite launched 19 October 2006 –C-band scatterometer - less sensitive to rain –Coverage ~ 60% of QuikSCAT 2 parallel 550-km swaths 720-km nadir gap –Operational retrievals expected later this year 50 km resolution 25 km retrievals by end of 2008 –Onboard METOP-B and METOP-C scheduled for launch every 4.5 years