The Polar Wind Product Suite Jeff Key*, Dave Santek+, Richard Dworak+, Chris Velden+, Jaime Daniels#, Andrew Bailey@ *NOAA/National Environmental Satellite, Data, and Information Service Madison, Wisconsin USA + Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin Madison, Wisconsin USA #NOAA/National Environmental Satellite, Data, and Information Service Camp Springs, Maryland USA @IMSG, Inc. 10th International Winds Workshop, Tokyo, 22-26 February 2010

The Polar Wind Product Suite VIIRS S-NPP (GOES-R algorithm) NOAA-20 Direct broadcast at Fairbanks and Sokankylä (heritage algorithm) Davis, Antarctica (under development) EW AVHRR Global Area Coverage (GAC) for NOAA-15, -18, -19 Metop-A, -B HRPT (High Resolution Picture Transmission = direct readout) at Barrow, Alaska, NOAA-18, -19 Rothera, Antarctica, NOAA-18, -19 Historical GAC winds, 1982-2012. Two satellites throughout most of the time series. MODIS Aqua and Terra separately Direct broadcast (DB) at McMurdo, Antarctica (Terra, Aqua) Casey, Antarctica (under development) LEO-GEO Combination of may geostationary and polar-orbiting imagers. Fills the 60-70 degree latitude gap. See the Notes section for additional information. Operational Operational Operational Operational Notes: “Operational” means official NESDIS operational product. NOAA-17 was decommissioned on 10 April 2013. AVHRR unusable since March 2010. NOAA-16 was decommissioned on 9 June 2014. MODIS winds at Tromsø, Norway (DB) were discontinued in September 2015. After a hardware (computer) failure, Ksat said that they did not want to support the project anymore. 5. MODIS winds at Fairbanks, AK were discontinued in 2014 and replaced by VIIRS winds. The MODIS data delivery became sporadic.

Polar Winds Product History 10-day MODIS winds case study made available Real-time AVHRR winds MODIS DB winds at Casey MODIS DB winds at Fairbanks LEO-GEO winds MODIS DB winds at McMurdo Mixed-satellite MODIS winds VIIRS DB winds at Fairbanks, Sodankylä Real-time Terra and Aqua MODIS winds AVHRR historical winds (v2) Metop AVHRR winds 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Daily AVHRR winds AVHRR HRPT winds from Rothera NESDIS MODIS winds on GTS MODIS DB winds at Tromsø VIIRS winds MODIS DB winds at Sodankylä ECMWF and NASA DAO demonstrate positive impact MODIS, AVHRR winds with nested tracking algorithm Terra MODIS winds in ECMWF operational system DB winds distributed via EUMETCast AVHRR HRPT winds from Barrow

MODIS Winds: Single Satellite Aqua and Terra winds are generated separately Data from the NOAA Real-Time System (aka “bent pipe”), composites of two or three 5-min granules. 1 km MODIS product (MOD021KM) is remapped to 2 km Cloud-track and water vapor winds NCEP’s GFS is used as the background Pros: Complete polar coverage Cons: Some MODIS granules arrive (very) late

AVHRR GAC and Metop Winds Six satellites: NOAA-15, -16, -17, -18, -19, and Metop 4 km for GAC; 2 km for Metop Cloud-track winds NCEP’s GFS is used as the background. NOAA-19 Pros: Complete polar coverage; excellent temporal sampling with all satellites. Good preparation for NPOESS VIIRS. Cons: No water vapor clear winds (no clear sky). Lower spatial resolution (GAC) yields fewer vectors. Height assignment uncertainty for thin clouds. Metop

MODIS Polar Winds 24-hr Loop Routine production of MODIS winds began in 2002

AVHRR Polar Winds NOAA-11 August 5, 1993 1800 UTC AVHRR winds are being generated with historical AVHRR (1982-2002) and in real-time. Yellow: Below 700 hPa Light Blue: 400-700 hPa Magenta: Above 400 hPa NOAA-11 August 5, 1993 1800 UTC NOAA-14 August 14, 1995 2300 UTC

Direct Broadcast Sites for Polar Winds and Other Products Fairbanks (Terra MODIS) McMurdo (Terra/Aqua MODIS) Rothera (HRPT AVHRR) Barrow (HRPT AVHRR) Tromsø/Svalbard (Terra MODIS) Sodankylä (Terra MODIS) Barrow McMurdo Fairbanks Svalbard Sodankylä Rothera

Historical AVHRR Polar Winds 1982 - 2009 Generally two satellites at any given time, NOAA-7 through -19 Global Area Coverage (GAC) data gridded at 5 km. Cloud-track winds using IR channel only (no water vapor channel). NCEP Reanalysis is background. Pros: An essential product for reanalysis projects. Cons: Low resolution. Height assignment uncertainty for thin clouds.

MODIS Winds in NWP Current Operational Users: European Centre for Medium-Range Weather Forecasts (ECMWF) - since Jan 2003. Testing DB winds. NASA Global Modeling and Assimilation Office (GMAO) - since early 2003. Deutscher Wetterdienst (DWD) – since Nov 2003. Testing DB winds. Japan Meteorological Agency (JMA), Arctic only - since May 2004. Testing DB winds. Canadian Meteorological Centre (CMC) – since Sept 2004. US Navy, Fleet Numerical Meteorology and Oceanography Center (FNMOC) –since Oct 2004. DB winds since Apr 2006. AVHRR GAC and MetOp since Nov 2007. UK Met Office – since Feb 2005. DB winds (experimentally) since Jun 2006. AVHRR GAC since . National Centers for Environmental Prediction (NCEP) and the Joint Center for Satellite Data Assimilation - since Nov 2005. MeteoFrance - since Jun 2006. MODIS, AVHRR, and all DB winds. National Center for Atmospheric Research (NCAR), Antarctic Mesoscale Model (AMPS) – since Oct 2006. DB winds (McMurdo) Australian Bureau of Meteorology - since Sept (?) 2007 Hydrological and Meteorological Centre of Russia (Hydrometcenter) – since mid-2010. DB winds.

Model impact studies have shown that the polar winds have a positive impact on weather forecasts not just in the polar regions, but globally. Figure: Anomaly correlations as a function of forecast range for the 500 hPa geopotential over the Northern Hemisphere extratropics (north of 20 degrees latitude). The study period is 5-29 March 2001. Including the MODIS winds in the model (red line) extends the 5-day forecast at a given accuracy by 3-6 hrs. (Figure courtesy of ECMWF) Forecast scores (anomaly correlations) are the correlation between the forecast geopotential height anomalies, with and without the MODIS winds, and their own analyses. From ECMWF

Forecast Busts (NASA GMAO) While the overall impact of the MODIS winds is positive, the impact at any given time may be positive, negative (occasionally), or neutral. What’s important, however, is that the MODIS winds significantly reduce the likelihood and magnitude of forecast “busts”, as shown below in time series of anomaly correlations. Southern Hemisphere Extratropics Arctic Blue is forecast with MODIS winds; red is control run

Impact in Tropics: GFS Model The Joint Center for Satellite Data Assimilation found that MODIS winds also impact hurricane track forecasts. Average hurricane track errors (nm) Frequency of superior hurricane performance 48.9   44.8 39.6 29.4 Cntrl 51.1 55.2 60.4 70.6 Cntrl + MODIS 74 64 52 34 Cases (#) 00-h 24-h 48-h 120-h Time 13.2  66.5 102.8 301.1 Cntrl 11.4 60.4 89.0 252.0 Cntrl + MODIS 74 64 52 34 Cases (#) 00-h 24-h 48-h 120-h Time In both tables, the forecast time is the bottom row. The control run (Cntrl) did not assimilate the MODIS winds. Percent of cases where the specified run had a more accurate hurricane position than the other run. Note: These cases are for hurricanes in the subtropics during 2004.