Presentation on theme: "Www.ncof.gov.uk OSTIA : Transition to an Operational System John Stark, Craig Donlon. GlobColour / Medspiration Workshop, 4-6 Dec. 2006."— Presentation transcript:
OSTIA : Transition to an Operational System John Stark, Craig Donlon. GlobColour / Medspiration Workshop, 4-6 Dec. 2006
Overview OSTIA : Operational Sea surface Temperature and sea Ice Analysis Description of the OSTIA system. –Data processing –Analysis & bias correction. –Products. From innovation to operation. –The transition process. –Operational status. Products and verification.
Operational SST & Sea Ice Analysis Daily 1/20° (~5.6km) global SST analysis using optimal interpolation. Blend of data sources, using satellite (microwave & IR) and in situ data. Now running daily in an operational suite starting at 0600 UTC. Persistence based; No explicit model. Uses sea ice analysis performed by EUMETSAT OSI-SAF (met.no / DMI). Sample analysis for 24 Jan 2006
Daily SST Basic Architecture Quality Control -Background check -Diurnal warming flagging Satellite Bias Estimation -Find match-ups -O.I. estimate. O.I. Analysis -Using 2 background error scales -Spatially varying backgrd. errors Data Sources Anomaly Persistence Forecast With relaxation to climatology
OSTIA : Source Data Sensor (Platform) TypeResolutionData SourceCoverageSubsa- mpling AMSR-E (Aqua) Microwave~25km (swath) Remote Sensing Systems (ssmi.com). L2P Format. Global (~1 million/day) 2 TMI (TRMM)Microwave~25km (swath) Remote Sensing Systems (ssmi.com). L2P Format. Tropics (~0.5 million/day) None AATSR (EnviSAT) Infra-red~1km (swath)Medspiration RDAC, L2P Format Global (~2 million/day) 3 AVHRR -LAC (NOAA 17 & 18) Infra-red~1/10° (Grid) Medspiration RDAC, L2P Format (NAR) & NAVOCEANO-JPL North Atlantic (grid) (~0.5 million/day) 3 AVHRR -GAC (NOAA 17 & 18) Infra-red~1km (Swath) NAVOCEANO-JPL(~2 million/day)None SEVIRI (MSG1)Infra-red0.1° (Gridded)Medspiration RDAC, L2P Format Atlantic sector (~2 million/day) None In-SituShips, drifting and moored buoys. In-situMet Office MetDB (GTS) Global (~25,000 /day) None Sea IceSSMI, Gridded10km, Gridded. OSI-SAF (Met.no)Global.None.
Bias correction : The Importance of AATSR AMSR-E Observations for 14 Dec. 05 Reference observations (With AATSR) Reference observations (No AATSR)
Bias correction : The Importance of AATSR Match ups (<25km) More match ups especially in data-sparse areas Analysed AMSRE bias for 14 Dec. Large impact from additional match ups
AATSR bias correction & SSES. AATSR bias specification has a significant impact on OSTIA. A short reanalysis showed that the AATSR SSES bias was too large. We appreciate the rapid response of Medspiration in changing the SSES bias (from 0.33 to 0.19). –But the change was not directly communicated to us… Difference (K) between operational OSTIA and a run with AATSR bias=0.0
Products Browsable SSTs and Anomalies
Products, Users and Applications Seasonal forecasting. –E.g. Winter forecast. Climate monitoring, inc. ENSO. Aviation Forecasting Centre Research –E.g. High resolution SSTs for monsoon modelling (U. Reading) Intercomparison / validation –NASA Short-term Prediction Research and Transition Centre (SPoRT) Data supplied in GHRSST L4 format via website : –http://ghrsst- pp.metoffice.com/pages/latest_analysis/ostia.h tmlhttp://ghrsst- pp.metoffice.com/pages/latest_analysis/ostia.h tml –ftp details available on request. NWP boundary condition. –Beginning extensive trials with NWP suite. Will participate in GHRSST GEO Action : DA to use ensemble techniques to improve SST uncertainty estimation. NASA Sport Web Page.
Innovation to Operation… The transition to an operational system has many advantages –Operators monitor the system 7 days a week. Robust system. –Machine resources are dedicated to the system ( UTC). –All procedures are clearly defined. –Allows rapid response to incidents. –Forces Good Practise, such as version control etc. But places requirements on the whole system: –All changes must be justified and documented. Any changes to data supply should be made a long time in advance if possible. Need stability in data delivery. –Not all operators have in-depth knowledge of the system. There should be simple how-to procedures for likely failure modes. –Processing MUST finish within the allocated time period.
Sea Ice Reanalysis Currently performing a sea ice reanalysis for the SSMI era ( ) –Hope to extend to SMMR ( ). –Using processing system developed for the EUMETSAT OSI-SAF. –Aim to quantify errors to provide a climate-quality product. Near 90 GHz Bootstrap NASA/Team Courtesy of Søren Andersen
SST Reanalysis Plans SST Reanalysis back to 1981 using available satellite data and in situ obs. –Aim to produce a homogenous 25+ year SST data set for seasonal forecasting by end of –Initially focus on Pathfinder (AVHRR) and (A)ATSR, by end of –Intercomparison with other GHRSST (re-)analyses. –Requires access to (A)ATSR data for effective bias correction. Ideally L2P format. –Open to collaboration Error covariances, ensemble techniques, D.V. (ocean colour?), aerosols (ocean colour)…
Priorities / Requests. Please maintain a continuous L2P data stream –Currently plan OSTIA to be the primary GMES Marine Core Services L4 SST output. (Operational backup from France). –Recommend the L2P format as it facilitates the transition to new data sources e.g. MetOp. Maintain AATSR Sentinel III –The presence of a high quality satellite SST data source is crucial to our bias correction strategy. –Bias correction scheme will be compromised without AATSR. Ensure (A)ATSR is available (in L2P) for reanalysis efforts. Please communicate changes to the system to users in an operational manner (timely and accurate).
Conclusions We are treating Medspiration as an operational service –Using the service on a daily basis. –Have been some hiccups that should be ironed out. Short interruptions to the service have occurred. OSTIAs strength is that is uses many complementary data sources. –Not totally reliant on a single data source – but accuracy significantly enhanced by AATSR. Sea ice reanalysis will be available for use.