New Australian High Resolution AVHRR SST Products from the Integrated Marine Observing System Presented at the GHRSST Users Symposium, Santa Rosa, USA, May 2009 Helen Beggs 1,2, Leon Majewski 2, George Paltoglou 1,2 and Edward King 1,3 1 Centre for Australian Weather and Climate Research, 2 Bureau of Meteorology, Melbourne, Australia 3 CSIRO Marine and Atmospheric Research

Nation-wide collaborative program designed to observe the oceans around Australia 27 Australian institutions mid-2007 to mid-2013 $AUS107M to install infrastructure for marine research All IMOS data available under the GOOS data access principles IMOS director, Dr Gary Meyers, keen to support GHRSST and place data on GTS See

Overview of IMOS Satellite SST Products Sub-Facility Aim Convert Australia’s existing HRPT AVHRR processing systems to produce more accurate and user friendly SST data files in GHRSST L2P (swath) and L3P (gridded) format from direct broadcast data from existing and future NOAA polar-orbiting satellites Data Streams L2P and L3P files will be produced in real-time and made available to researchers via the IMOS Australian Ocean DAAC and GHRSST. Raw AVHRR data back to ~1990 will also be reprocessed to L2P and L3P files.

BoM HRPT AVHRR Processing Data received at 8 reception stations and sent to BoM (Melbourne) as raw data Overlapping raw data is stitched using CSIRO code (Edward King) Cloud masks determined (CLAVR-1) SSTs computed for ~1 m depth using NLSST (day) and MCSST (night) algorithms and regression coefficients based on regional buoy data AVHRR SSTs matched with buoy SSTs (following Medspiration MDB method) Single Sensor Error Statistics for each proximity confidence value (0,1,2,3,4,5 km to nearest cloudy pixel) calculated using 3 weeks of matches to ±12 km and ± 2 hours Locations of X/L band stations

New SST products with proximity confidence value of 5 (best) exhibit roughly half the RMS error of the BoM pre- existing HRPT AVHRR level 2 SST data from NOAA-17 and NOAA-18 satellites For Australian region and 17 Dec 2008 to 4 Apr 2009: –NOAA-17 Stand. Dev. = 0.22°C (night), 0.42°C (day) –NOAA-18 Stand. Dev. = 0.32°C (night), 0.40°C (day) Achieved by –Setting proximity confidence 5 data to be 6 km away from cloud –Data restricted to satellite zenith angles < 50° –Stitching overlapping raw data –Using QC’d regional not global buoy obs for regression –Optimise the fit of the AVHRR radiances to buoy SSTs Accuracy of new IMOS AVHRR SST

HRPT AVHRR SST L2P Satellites: Currently NOAA-17 and NOAA-18 (NOAA-19 soon) Coverage: 20  N to 70  S, 50  E to 160  W depending on receiving station Ground Stations: Melbourne, Hobart, Darwin, Perth, Alice Springs, Townsville Spatial Resolution: ~1.1 km Depth: skin BTs converted to SST1m (using buoy bulk SSTs) Position Accuracy: ±1 km Timeliness: < 3 hours Data Product: Stitched single swath files of L2 SST (one per orbit) in L2P netCDF format, including bias, SD, NWP winds and quality flags for each pixel NOAA-18 HRPT AVHRR L2P SST 10 April 2009

HRPT AVHRR SST L2P Satellites: Currently NOAA-17 and NOAA-18 (NOAA-19 soon) Coverage: 20  N to 70  S, 50  E to 160  W depending on receiving station Ground Stations: Melbourne, Hobart, Darwin, Perth, Alice Springs, Townsville Spatial Resolution: ~1.1 km Depth: skin BTs converted to SST1m (using buoy bulk SSTs) Position Accuracy: ±1 km Timeliness: < 3 hours Data Product: Stitched single swath files of L2 SST (one per orbit) in L2P netCDF format, including bias, SD, NWP winds and quality flags for each pixel NOAA-18 HRPT AVHRR L2P SST 10 April 2009

HRPT AVHRR SST L2P Satellites: Currently NOAA-17 and NOAA-18 (NOAA-19 soon) Coverage: 20  N to 70  S, 50  E to 160  W depending on receiving station Ground Stations: Melbourne, Hobart, Darwin, Perth, Alice Springs, Townsville Spatial Resolution: ~1.1 km Depth: skin BTs converted to SST1m (using buoy bulk SSTs) Position Accuracy: ±1 km Timeliness: < 3 hours Data Product: Stitched single swath files of L2 SST (one per orbit) in L2P netCDF format, including bias, SD, NWP winds and quality flags for each pixel NOAA-18 HRPT AVHRR L2P SST 10 April 2009

HRPT AVHRR SST L2P Satellites: Currently NOAA-17 and NOAA-18 (NOAA-19 soon) Coverage: 20  N to 70  S, 50  E to 160  W depending on receiving station Ground Stations: Melbourne, Hobart, Darwin, Perth, Alice Springs, Townsville Spatial Resolution: ~1.1 km Depth: skin BTs converted to SST1m (using buoy bulk SSTs) Position Accuracy: ±1 km Timeliness: < 3 hours Data Product: Stitched single swath files of L2 SST (one per orbit) in L2P netCDF format, including bias, SD, NWP winds and quality flags for each pixel NOAA-18 HRPT AVHRR L2P SST 10 April 2009

HRPT AVHRR Composite SST L3P Nighttime NOAA-18 HRPT AVHRR SST1m L3P Daytime NOAA-18 HRPT AVHRR SST1m L3P Satellites: Currently NOAA-17 and NOAA-18 (NOAA-19 soon) Coverage: 0  N to 55  S, 90  E to 180  E Ground Stations: Melbourne, Hobart, Darwin, Perth, Alice Springs and Townsville. Spatial Resolution: 0.01° x 0.01° Depth: SST1m Position Accuracy: ±1 km Timeliness: < 3 hours Data Product: Composite, single sensor, single day and single night L3P netCDF files created by gridding L2P data using mapx library. For each pixel there is bias, SD, NWP wind and quality flags. 10 April 2009 NOAA-18

Benefits from Australian AVHRR L2P and L3P Products BLUElink>: More accurate regional daily foundation SST analyses (“RAMSSA”) Research into high-resolution ocean models, coral bleaching, coastal ocean research, diurnal warming and other research requiring ~ 1km SST data in Australian region Consistent, accurate, 1 km resolution, regional SST data set back to at least 1990 useful for climate studies Reprocessed Australian HRPT AVHRR L2P SST could be ingested into future GHRSST SST reanalyses (NODC)

Data Dissemination GHRSST (By Dec 2009) –Via OPeNDAP, Aspera, HTTP and FTP –For RT data: –For Reanalyses: AO-DAAC (By 30 June 2009) –Via OPeNDAP, HTTP and FTP as ASCII, HDF or netCDF files from

Australian Ocean Distributed Active Archive Centre (AO-DAAC)

Dr Helen Beggs, Ocean Prediction Group, Centre for Australian and Weather Research, Bureau of Meteorology, 700 Collins St, Melbourne, Vic, Australia