GRAS SAF System, Products, and Archive

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GRAS SAF System, Products,and Archive
Frans Rubek Martin Bjært Sørensen GRAS SAF
Team Danmarks Meteorologiske Institut
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EPS/Metop Radio Occultation from GPS
EPS/Metop
Vertical profile of refractivity
GPS
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Typical 24-hour EPS/MetopRadio Occultation
Distribution
1 LEO with two occultation antennas
24 GPS satellites
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Data Levels and Processing
EPS/Metop Measurement
GRAS SAF Level 1b -gt 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, Qualit
y check
EPS Core Ground Segment Level 0 -gt Level 1a
Processing Level 1a -gt Level 1b Processing
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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
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Initial Joint Polar System (IJPS)(EPS NPOESS
Program)
NOAA N, N (p.m.), NPOESS
METOP (a.m.)
SAF
SAF
EUMETSAT POLAR SYSTEM (EPS)
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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.
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NRT Data Flow as a Function of Time
Recording Orbit N
Recording Orbit N2
Recording Orbit N1
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 N1
Processing Orbit N
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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

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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
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User Requirements for NWP
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User Requirements for Climate Research
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GRAS SAF Prototype TemperatureProfile from CHAMP
Data
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GRAS SAF Prototype TemperatureStatistics using
CHAMP Data
1630 profiles January 6 23 2002
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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
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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)
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GRAS SAF Processing Chain

• 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)

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Software Platforms

• Distributed scaleable system using CORBA
• Based on Sun workstations and Linux PCs
• Python
• OmniORB
• UNIX shell
• FORTRAN 77/90

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Interfaces
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GRAS SAF Processing System
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Hardware Components
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Data Distribution

• Near Real Time products
• RMDCN ( BUFR only)
• GRAS SAF ftp server
• Off-line enhanced products
• User Requests at EUMETSATs UMARF V2 User
  services
• - and delivery at the GRAS SAF ftp server
• - or via DVD/CD-ROM

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NRT Dissemination
Regional Meteorological Data Communication
Network for ECMWF and WMO Region VI
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UMARF V2 Area Selection
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UMARF V2 Satellite Search
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UMARF V2 Product Details
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UMARF V2 Order Follow-Up