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GRAS SAF System, Products, and Archive. Frans Rubek & Martin Bjært Sørensen GRAS SAF Team Danmarks Meteorologiske Institut. EPS/Metop Radio Occultation from GPS. EPS/Metop. Vertical profile of refractivity. GPS. Typical 24-hour EPS/Metop Radio Occultation Distribution. 1 LEO with two
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GRAS SAF System, Products,and Archive Frans Rubek & Martin Bjært Sørensen GRAS SAF Team Danmarks Meteorologiske Institut
EPS/Metop Radio Occultation from GPS EPS/Metop Vertical profile of refractivity GPS
Typical 24-hour EPS/MetopRadio Occultation Distribution 1 LEO with two occultation antennas 24 GPS satellites
Data Levels and Processing EPS/Metop Measurement GRAS SAF Level 1b -> Level 2 Processing, Dissemination, Archiving, ... End Users Level 2 Data: Refractivity, pressure, temperature, and humidity profiles, Validation Data ... Raw Data Downlink Level 1b Data: Bending Angles, Impact Parameters, Auxiliary Data, ... Level 1a Data: Phase Delays, Doppler Shifts, SNR, Earth Location Data, ... Level 0 Data: Phase and Amplitude Data, Tracking and Ancillary Data, Ground Site Data, ... High-latitude Downlink Site Demultiplexing, Quality check EPS Core Ground Segment Level 0 -> Level 1a Processing Level 1a -> Level 1b Processing
GRAS SAF Data Flow Model Occultation GPS Ground Station measurements Networks EPS/ Metop EUMETSAT Level 0 EPS / CGS EPS data Level 0 GRAS downlink Ground Processor GPS POD Level 1b Level 1b data EPS Primary NRT User Terminal Operational GRAS SAF NWP Level 1b users Development NWP Processing Center centers UMARF Archiving Client Center Server Ancillary NRT products data (Level 2) Offline Software products Archive Education / Help desk (Level 2) UMARF Public outreach RMDCN, HTTP, DVD/CD - ROM HTTP per mail FTP GTS End users
Blind orbits Global data data dump dump Global data dump NOAA global data METOP blind orbits EUMETSAT NOAA CNES METOP global data IASI TEC NOAA blind orbits Initial Joint Polar System (IJPS)(EPS + NPOESS Program) NOAA N, N’ (p.m.), NPOESS METOP (a.m.) SAF SAF EUMETSAT POLAR SYSTEM (EPS)
GRAS SAF Products Time Requirements Near-Real Time Products: (NRT) Offline Products: To be delivered less than 3 hours after measurement, using RMDCN (Regional Meteorological Data Communication Network), GTS, a.o. Mainly for NWP use. Improved products re-processed using precise satellite orbits, additional NWP input, etc. To be delivered less than 30 days after measurement, using FTP, DVD/CD-ROM, WWW download, a.o. Mainly for climate research use.
NRT Data Flow as a Function of Time Recording Orbit N Recording Orbit N+1 Recording Orbit N+2 On board data acquisition Elementary unit Satellite dump to CDA CDA to EPS/CGS transmission EPS/CGS Level 1b processing NRT Level 1b transmission to SAF GRAS SAF NRT Level 2 processing GRAS SAF NRT Level 2 dissemination TIME Processing Orbit N+1 Processing Orbit N
GRAS SAF Products Overview • Data Product Characteristics • Bending Angle Profile (Offline only) Bending angle as a function of impact • parameter • Refractivity Profile Neutral Refractivity as a function of height and location of the occultation • Observation Error profile and covariance matrices of the observables. • Characteristics Time information for the occultation data. • Latitude, longitude and radial position of the occultation • products in geodetic coordinates. • Temperature Profile Temperature (dry/wet) and error estimate as a function of • height and location of the occultation • Specific Humidity Profile Specific humidity (water vapor) and error estimate as a function of height and location of the occultation • Pressure Profile Dry pressure and error estimate as a function of height and • location of the occultation, including surface pressure • Surface Pressure (NRT only) Pressure estimate at surface level
GRAS SAF Assimilation S/W Products Statistically optimal 1D-Var refractivity retrieval code Forward models for 4D-Var: - Direct assimilation of refractivity profiles into an NWP model - Plane-averaged refractivity forward model for assimilation into an NWP model - Direct assimilation of bending angle as a function of impact parameter into an NWP model
GRAS SAF Prototype TemperatureStatistics using CHAMP Data 1630 profiles January 6 – 23 2002
NRT & Offline Processing Flowchart 1a NOISE REDUCTION (LP FILTERING), QUALITY CHECK, COORDINATE TRANSFORMATION, BACK PROPAGATION/CANONICAL TRANSFORM ROUTINE (below 17 km), BENDING ANGLE ROUTINE (above 17 km) PHASE AND AMPLITUDE MEASUREMENTS + ORBIT INFORMATION (OFFLINE) 1b 1b BENDING ANGLES (NRT) BENDING ANGLE PROFILE IONOSPHERE CORRECTION, STATISTICAL OPTIMIZATION (NRT ONLY) ABEL TRANSFORM ROUTINE BACKGROUND TEMPERATURE, HUMIDITY, and SURFACE PRESSURE 2 REFRACTIVITY PROFILE 1D-VAR RETRIEVAL (NRT ONLY), ITERATIVE ALGORITHM (OFFLINE ONLY) HYDROSTATIC EQUILIBRIUM, IDEAL GAS EQUATION 2 2 DRY PRESSURE, DRY TEMPERATURE WET TEMPERATURE, SPECIFIC HUMIDITY, SURFACE PRESSURE (NRT ONLY)
Near real time retrieval: from bending angle to level 2 Off-line retrieval: from observed phase to level 2 Processing steps: Excess phase (offline only) Bending angle (offline only) Refractivity “Dry” temperature, pressure and density “Wet” temperature, pressure and density Surface pressure (NRT only) GRAS SAF Processing Chain
Distributed scaleable system using CORBA Based on Sun workstations and Linux PC’s Python OmniORB UNIX shell FORTRAN 77/90 Software & Platforms
Request Request Manager Manager TaskManager TaskManager Monitor Monitor Client Client GTS GTS EndUser EndUser ReportGe ReportGe System System nerator nerator SendD SendD FTP FTP ReportGen ReportGen ata ata erator erator store/retrieve store/retrieve Archive Archive Manager Manager TaskMan TaskMan ager ager UMARF UMARF store/retrieve store/retrieve store/retrieve store/retrieve Archive Archive Proxy Proxy TaskManager TaskManager Client Client store/retrieve store/retrieve Product Product Generator Generator do_job do_job TaskManager TaskManager TaskManager TaskManager Archive Archive Archive Archive process process Client Client Client Client Proxy Proxy Proxy Proxy Processor Processor store/retrieve store/retrieve Data Data Retriever Retriever registrer registrer JobManager JobManager EPS EPS EPS EPS IGS IGS ECMWF ECMWF NRT NRT FTP FTP GRAS SAF Processing System
Internet Router RMDCN Router Firewall Firewall GTS Interface FTP Server Data switch Firewall Level 1B downlink NRT Terminal UMARF Client Data Reciever Task Managment NRT Processor OFF-Line Processor Archive & User facilities External lines Deployment Site Ethernet GRAS SAF Private Ethernet Hardware Components
Near Real Time products: RMDCN ( BUFR only) GRAS SAF ftp server Off-line enhanced products: User Requests at EUMETSAT’s UMARF V2 User services - and delivery at the GRAS SAF ftp server - or via DVD/CD-ROM Data Distribution
NRT Dissemination Regional Meteorological Data Communication Network for ECMWF and WMO Region VI