Operational Use and Impact of Satellite Remotely Sensed Ocean Surface Vector Winds in the Marine Warning and Forecasting Environment

(NASA) launched QuikSCAT, a microwave radar system known as a scatterometer, specifically designed to retrieve OSVW over the global ocean (Jet (NESDIS) worked together to implement a near-real-time OSVW processing and distribution system at NOAA to allow QuikSCAT data to be used by the operational weather forecasting and warning communities around the world. Although QuikSCAT was not the first scatterometer launched into Verhof and Stoffelen, 2008), its reliability , high quality, relatively fine spatial resolution, and large daily geographical coverage resulted in its having the largest impact of any scatterometry mission in the operational marine weather forecasting and warning world (Jelenak and Chang, 2008). In 2002, a National Oceanographic Partnership Program (NOPP) project was initiated to exploit the currently and soon-to-be-available satellite OSVW data in the operational weather forecasting and warning environment. This effort had three main objectives: (1) to quantify the impacts of QuikSCAT OSVW data in the operational short-term warnings and forecasts issued by the National Weather Service (NWS) Ocean Prediction Center (OPC) and National Hurricane Center (NHC), (2) to improve the use of satellite OSVW data in the public and private sector, and (3) to transition promising research products toward operational use. This project brought together people from the federal government, private industry, and academia and initiated what has become one of the most successful transitions of a research data stream (QuikSCAT OSVW) into operational use, where it continues to have a profound impact on marine weather warning and forecasting. In the United States, NWS is responsible for providing marine weather warning and forecast information, and it has international obligations to provide the same within its areas of responsibility under the umbrella of the World Meteorological Organization. Additionally, the US military provides marine weather forecasting and warning services to support military operations.

space (Naderi et al., 1991;Stoffelen and Anderson, 1993;Gelsthorpe et al., 2000;Verhof and Stoffelen, 2008), its reliability, high quality, relatively fine spatial resolution, and large daily geographical coverage resulted in its having the largest impact of any scatterometry mission in the operational marine weather forecasting and warning world (Jelenak and Chang, 2008). In

OPER atIONal USE
In the United States, NWS is responsible for providing marine weather warning and forecast information, and it has international obligations to provide the same within its areas of responsibility under the umbrella of the World Meteorological Organization.
Additionally, the US military provides marine weather forecasting and warning services to support military operations.
A combination of the NWS areas of responsibility with those of the military's Joint Typhoon Warning Center (JTWC) provides coverage of much of the world's ocean (Figure 1).

INtROdUCtION
The ocean comprises over 70% of         scheme produces ultra-fine-or ultrahigh-resolution (UHR) wind speed and normalized radar-cross section (NRCS) images of Earth's surface from QuikSCAT (Long, 2004).These ultrafine-resolution NRCS images reveal details of the wind structure in tropical cyclones, and together with the OSVW measurements have become an important tool in TC forecasting and warning, especially where aircraft reconnaissance is not available (Edson et al., 2002).The NOAA QuikSCAT NRT processing system now produces refined UHR, storm-centered, "postage-stamp" wind and NRCS products, which are posted to the NRT QuikSCAT storm page (http:// manati.orbit.nesdis.noaa.gov/cgi-bin/qscat_storm.pl)(see Figure 10, where a land distance flag was recently added; Owen and Long, 2008a;Plagge et al., 2008).A careful study of eight years of QuikSCAT data revealed that UHR wind retrieval can accurately locate hurricane centers compared with best track locations, even in early stages of development (Said and Long, 2008).
MERS has developed an experimental UHR simultaneous wind/rain wind retrieval algorithm along with a new wind direction ambiguity removal algorithm, both of which are currently undergoing validation experiments (Williams andLong, 2006, 2008a,b;Owen and Long, 2008b).

USE IN thE PRIVatE SECtOR
In addition to government agencies exploiting QuikSCAT OSVW, there are also a surprising number of users in the private sector and the general public.
We   OSVW retrieval capability by an order of magnitude over that provided by QuikSCAT (Gaston and Rodriguez, 2008).The primary improvements are: finer horizontal resolution of surface wind estimates, decreased sensitivity to the effects of rain in the wind estimates, the ability to retrieve much higher wind estimates (> 50 m s -1 ), and the ability to provide winds to within 5 km of the coast.In parallel, NOAA conducted a study assessing the impacts of both a QuikSCAT-equivalent and an improved OSVW capability, which resulted in the document QuikSCAT Follow-On Mission: User Impact Study Report (Jelenak and Chang, 2008).
U l S .C h a N g , Z O R a N a J E l E N a k , J O S E P h M .S I E N k I E W I C Z , R I C h a R d k N a B B , M I C h a E l J .B R E N N a N , d aV I d g .l O N g , a N d M a R k F R E E B E R g N O P P S P E C I a l I S S U E » O C E a N O B S E R V I N g P l at F O R M S a N d S E N S O R S worked together to implement a near-real-time OSVW processing and distribution system at NOAA to allow QuikSCAT data to be used by the operational weather forecasting and warning communities around the world.Although QuikSCAT was not the first scatterometer launched into 2002, a National Oceanographic Partnership Program (NOPP) project was initiated to exploit the currently and soon-to-be-available satellite OSVW data in the operational weather forecasting and warning environment.This effort had three main objectives: (1) to quantify the impacts of QuikSCAT OSVW data in the operational short-term warnings and forecasts issued by the National Weather Service (NWS) Ocean Prediction Center (OPC) and National Hurricane Center (NHC), (2) to improve the use of satellite OSVW data in the public and private sector, and (3) to transition promising research products toward operational use.This project brought together people from the federal government, private industry, and academia and initiated what has become one of the most successful transitions of a research data stream (QuikSCAT OSVW) into operational use, where it continues to have a profound impact on marine weather warning and forecasting.
Figure2.typical daily coverage of ocean surface vector winds from NaSa's QuikSCat, resulting in 90% daily coverage of the world's ocean.

Figure 1 .
Figure 1.Map showing the combined areas of responsibility of all National Weather Service offices with marine warning and forecasting responsibilities, as well as the US military's Joint typhoon Warning Center (JtWC).JtWC (orange), the National hurricane Center (blue), and the Central Pacific hurricane Center (green) share the warning responsibility for tropical cyclones.

Figure 4 .
Figure 4.The broad swath of QuikSCat winds allows forecasters to examine the character of swell generation regions in cyclones.also, despite frequent errors in tropical cyclone (tC) center location in the automated QuikSCat solution, manual analysis of directional ambiguities can be performed to locate the tC centers using all the possible QuikSCat solutions.This tool has been essential for detection and center location of Pacific tCs not sampled by aircraft reconnaissance flights.Courtesy of Roger Edson, Science and Operations Officer, NOAA/National Weather Service Office Guam

Figure 6 .
Figure 6.QuikSCat 12.5-km-resolution wind retrievals in a hurricane-force gulf of tehuantepec gap wind event on November 22, 2006.

Figure 5 .
Figure 5. Percentage of atlantic (blue) and East Pacific (red) tropical cyclone discussions issued by the National hurricane Center that mention QuikSCat (2000-2007).

Figure 7 Figure 7 .
Figure 7 clearly shows forecaster reliance on QuikSCAT winds-as data

Figure 8 .
Figure 8.The 2006 "hanukkah Eve" wind storm occurred on the evening of december 14 and extended into the morning of december 15.The storm blew down thousands of trees, knocked power out for close to 1.5 million customers, damaged hundreds of structures and homes, and injured dozens of people in the US Pacific Northwest and British Columbia, Canada.hospitals treated 275 people for carbon monoxide poisoning following the storm.

Figure 9 .
Figure 9. QuikSCat provided measurements of wind speed and direction to help determine the cause for the sinking of a vessel in the Red Sea on February 2, 2006.
have received emails from a wide range of folks, including the meteorologist aboard an aircraft carrier, the surfing community, recreational and racing vessels, and the offshore wind farm industry.Through its WeatherNet system, OCENS Inc. (a participant in this NOPP-funded effort) made QuikSCAT OSVW data available to its market base, which includes sail and power cruising, ocean racing, commercial and sport fishing, tug and barge operations, and shipping.Surveys conducted by OCENS found most user feedback was very positive.A broad set of their users found that the QuikSCAT data are most beneficial in areas where the weather is generally stable and the data are used to locate slight variations in wind patterns to enable optimum vessel routing.More advanced users have taken advantage of the availability of the QuikSCAT data to "tune" GRIB (GRIdded Binary) wind forecasts produced by the NWS Global Forecast System model and/or WaveWatch III models.Most notably, this practice was employed to startling success by the Spirit of Sark, a racing yacht participating in the Global Challenge Around-the-World Race, which is detailed in the following quote from an email received from Simon Bell, Sark's navigator: Cold-Front Dissection: I have attached a GRIB-Explorer Screen-Shot for our first Brazilian-cold front (CF) [shown in Figure 11].Using GRIB-Explorer we were able to calibrate our GFS Grib-file vs QuikSCAT and determine how far ahead/behind the GFS-Forecast was.From this, we could estimate our ETA at the Cold-Front.We were also able to "see" inside the Cold-Front and understand the structure of the Front and what conditions we could expect.We were able to see from the Screen-Shots that we could expect the wind to drop & back as we approached the CF and then jump to 30 kts from the SW at the Front.Using this info we flew our Spinnaker to within 30 seconds before the SW-Wind hit...and WOW did it hit.We were also able to understand the dynamics of the Cold-Front.The weather-forecasts reported a Cold-Front at Location XY heading SE and moving NE at 10knts.By observing the QuikSCAT Data over time, we understood that the situation was MUCH more complicated!The N-side of the CF is driven by the NW-Wind and features on the N-Side therefore drift SE along the Cold-Front with this Wind.Then the whole Cold-Front does indeed Track NE...and combining this with the Drift we understood that features drift West!On the S-Side of the CF the opposite is true...features on the S-Side are driven by SE-Wind and therefore drift NW along the CF.Then with the whole Cold-Front Tracking NE...and combining this with the Drift we understood that features drift North!This helped us understand (too late) how to line-up on Gates thru the Cold-Front when one presented itself.Spirit of Sark subsequently won the rugged Buenos Aires to Wellington Third Leg of the Global Challenge while making extensive use of QuikSCAT data acquired through WeatherNet and displayed in GRIB Explorer.Similar tuning techniques were employed by racers participating in

Figure 10 .
Figure 10.Early examples of ultra-high-resolution (UhR) processing of QuikSCat data for hurricane katrina on august 27, 2005.(left) UhR radar h-pol normalized radar-cross section image.high winds show up as lighter values, and lower wind speeds are darker.land is colored green.(Right) QuikSCat UhR wind speeds.Mesoscale structure and convective events are clearly visible.

Figure 11 .
Figure 11.The gRIB-Explorer display of QuikSCat wind vectors and wind speeds (color coded), depicting a cold front off the coast of Brazil on October 27, 2004.

Finally
and twice as coarse spatial resolution wind retrievals as those provided by QuikSCAT.NOAA is also exploring access to data from Indian and Chinese satellites that will be launched in the next few years, as well as a partnership with the Japanese Exploration Space Agency (JAXA) to fly a QuikSCAT follow-on instrument as part of JAXA's Global Climate Observation Mission program.CONClUSION Our NOPP project established personnel resources at OPC, NHC, and NESDIS that significantly strengthened existing collaborations.Because of this enhanced partnership, QuikSCAT OSVW data were transitioned in an optimal and efficient manner into the operational NWS environment.Quantifying the impacts of these data allowed us to better understand the value of this observing system capability.Additionally, we were able to determine and justify the actual operational weather warning and forecasting requirements for satellite OSVW, which will be important for the design of a QuikSCAT follow-on mission to continue this now routinely used OSVW capability.Academic and private sector partnerships were also enabled by our NOPP project.Working with Brigham Young University, we transitioned new QuikSCAT products into operations, and we expanded the use of QuikSCAT OSVW products in collaboration with OCENS Inc.The partnerships enabled by this NOPP opportunity had a significant role in the successful transition of QuikSCAT OSVW data into the operational environment at NOAA and beyond.Ocean surface vector wind data received from NASA QuikSCAT have revolutionized operational marine weather warnings, analyses, and forecasting.QuikSCAT data give forecasters the ability to see the detailed wind field over vast ocean areas, to see the inner structure of ocean storms, and to identify areas of ocean wind wave generation.When issuing marine wind forecasts and warnings, these surface wind data give forecasters a higher level of situational awareness, providing a rich data source in areas not sampled by buoys and other wind platforms, ultimately resulting in improved forecasts and warnings.An impact study in the fall of 2002 by Von Ahn et al. (2006) demonstrated that the number of wind warnings issued for extratropical cyclones by OPC increased by 30% in the North Atlantic and 22% in the North Pacific when QuikSCAT winds were used in the forecast process.Based on this improved detection capability, OPC introduced a new warning category for hurricane-force winds in nontropical ocean storms in late 2000.For tropical cyclones, QuikSCAT data have become an important analysis tool at the National Hurricane Center, the Central Pacific Hurricane Center, and the Joint Typhoon Warning Center, providing information on the intensity of tropical depressions and tropical storms; improving the identification and analysis of TC center locations, especially in developing systems; and providing critical information on TC wind field structure, especially in data-sparse open ocean areas (e.g., Brennan et al., in press).Today, QuikSCAT data are used around the world to help provide accurate marine weather warnings and forecasts.Users span government agencies, commercial companies (ship routing, offshore wind farms, weather information providers), and individual users (surfers, sailboat racers, recreational boaters).Satellite OSVW data from QuikSCAT impact many facets of daily life in marine and coastal communities.QuikSCAT OSVW data have successfully been transitioned to use in the operational environment.The next challenge will be to establish a sustained satellite OSVW observing capability that builds upon the knowledge gained from over nine years of QuikSCAT OSVW.