The Asia-Pacific Regional
ATOVS Retransmission Service

Current Service Announcement: Nil Current.

• Definition - What is RARS?
• The Australian Contribution to RARS
  • Coverage
  • Processing Software
  • Timeliness
  • Availability
  • Distribution mechanism
  • File naming and structure
  • Obtaining AP-RARS
• Planned Acquisition Schedule
• Acquired passes in last 24 Hours
• Scheduling Strategy
• Quality monitoring
• Service News
• Useful Links
  
  
  

Definition - What is RARS?

Regional ATOVS Retransmission Services (RARS) are operational arrangements for the real-time acquisition of polar-orbiting satellite data over a wide region containing a network of direct readout stations and their rapid delivery to the global user community through regional Processing Centres. It is a global, coordinated initiative comprising several regional components of which the Asia Pacific Regional ATOVS Retransmission Service (AP-RARS) is one which covers the Asia-Pacific Region

General information for this service can be found on the World Meteorological Organization's RARS web site.

The Australian contribution to AP-RARS

The service offered by Australia to the meteorological community consists of:

Processed data from NOAA-15, NOAA-16, NOAA-17 and NOAA-18 from 7 sites. These sites are located at:

Coverage

The following image shows the coverage of the Bureau's polar orbiting satellite reception ground stations. Please note that there is currently no operational RARS from Casey or Davis, although that is expected during 2008.

(click on image for more detailed version)

Processing Software

The current software version is ATOVS and AVHRR Pre-processing Package (AAPP) version 6.7. for information on this package, visit this link: http://www.metoffice.gov.uk/research/interproj/nwpsaf/aapp/

Target timeliness of the service

The Australian RARS service is capable of delivering >90% data within 30 minutes from the start of the ingest from all ingest sites except Davis and Casey. Since Davis and Casey are situated on the Antarctic Continent, there is a limited bandwidth available for data transfer. Data from Davis and Casey should be available approximately 60 minutes from the start of the ingest.

Target availability of the service

Given the antenna capacity of the Bureau sites, the target availability of the service is 90%. This figure is defined as the ratio of the actual number of individual product files to the number of product files the Bureau has the capacity to produce. This is based on the EARS standard that can be found at: http://www.eumetsat.int/Home/Main/What_We_Do/Satellites/EARS_System/index.htm

Distribution mechanism

The primary distribution mechanism is via the Global Telecommunications System (GTS): currently data are sent to the Regional Telecommunications Hub in Tokyo (RTH Tokyo). Data are also sent to Exeter, and in the future this is expected to expand to include Washington and possibly other sites

File naming and structure

Extensive discussions on the file naming issue were held at the 7th Meeting of the Asia-Pacific Satellite Data Exchange and Utilization (APSDEU-7) in Sept 2006 and it was agreed by those present at this meeting on the format which complies with the WMO Manual on the GTS, Volume II, Attachment II-15.

Since APSDEU-7 there was a further revision at the WMO Integrated Global Data Dissemination Service Implementation Group Meeting (pdf file 276 kb) (IGDDS-IG) and since this meeting it is expected that a further amendment to the format will be made in mid 2008.

A draft for discussion of the proposed new filename and structure format, leading towards decisions at upcoming WMO and international meetings, is available in Word^® format, here: (rars_filename_updates3c.doc) (106 kB) and an early draft paper from April 22, 2008 on related issues by Robert Husband (WMO) is also available in Word^® format, here:
(RARS-IG2-RARS_Coding_and_Format_Issues_v0[1].7.doc) (180 kb).

Currently, the format for the Asia-Pacific RARS is outlined below:

• characters Z, RARS, C, R and bufr.bin are all fixed;
• cccc: location indicator for the compiling center of the file (e.g. RJTD for Tokyo);
• yyyyMMddhhmmss: time of compilation in UTC;
• rrr: HRPT station identifier (see note below);
• AAPP filename: Actual AAPP filename.  The dot(.) character in the AAPP filename shall be replaced by a minus(-) sign or underscore(_).

• INSTLEV is the instrument from which the data was originally derived and the level (nature) to which the calibration, navigation and remapping has been applied (HIRS level 1d)
• SATIMG is the satellite name and number (NOAA-17)
• YYYYMMDD HHMN is the Date and time of reception of the first scan line in the NOAA data, taken from the HRPT file (22:23 UTC 02 December 2006)
• NNNNN is the orbit number (22652) and
• LEVEL is the level to which the data has been processed (level 1 d)

Obtaining AP-RARS

The contact/coordinator for the Asia-Pacific RARS is Dr David Griersmith, Superintendent, Space-Based Observations Section. For any enquiries concerning the Asia-Pacific RARS, please contact David Griersmith, or in his absence, Anthony Rea.

Scheduling strategy

Following is a list of current polar orbiter ingest priorities (as at 16 August 2007); the pairs of priority values refer to the AM and PM orbits (daytime / nighttime passes) and if two or more satellites have the same value then the longer of the two orbits is tracked.

¹ Missing priorities are given to non RARS satellites such as Aqua, Terra and SeaWiFS

Operational points of contact

1. Dr Gary Weymouth

   Space-Based Observations Section
   G.Weymouth@bom.gov.au
   +61 3 9669 4833

2. Gerald McNamara

   Space-Based Observations Section
   G.McNamara@bom.gov.au
   +61 3 9669 4717

3. Dr. Anthony Rea

   Space-Based Observations Section
   A.Rea@bom.gov.au
   +61 3 9669 4498

Note that these persons will only be available 09:00 to 17:00 AEST

Planned Acquisition Schedule

This part of page is still under construction

Acquired Passes within last 24 Hours

Quality monitoring

RARS data quality monitoring takes place at two levels:

• The Regional Processing Centres are responsible for monitoring the performance of the RARS in their region;
• The Numerical Weather Prediction Satellite Application Facility (NWP SAF) routinely compares the data from all the RARS with global data.

In addition, data quality flags and indicators are generated when the data are processed by the AAPP software and are embedded in the format of the retransmitted data alerting users to any inherent quality problems that might be present in the data themselves.

Monitoring by Regional Processing Centres

The standards for RARS operators are defined in an Operator Standards (pdf file) document. These standards include a definition of service related information that should be gathered and published. Each RARS Regional Processing Centre is responsible for monitoring the completeness of the data collected from the regional network of direct readout stations and retransmitted by the Centre. Data reception monitoring is based on a comparison of the actual data received by the Regional Processing Centre with that expected from the nominal regional configuration. Data retransmission monitoring involves maintaining a record of the completeness and timeliness of all data sets retransmitted. The results of all data monitoring are published on the Regional Processing Centres' web sites. (e.g. The following link will take you to the monitoring web site for the Asia-Pacific RARS at the JMA Meteorological Satellite Center). Timliness of the RARS data from all stations in the network to the Regional Telecommunications Hub in Tokyo (RTH Tokyo) can be seen at http://mscweb.kishou.go.jp/rars/time_index.htm

Service News

Useful Links

• WMO RARS website
• Second meeting of the RARS Implementation Group (RARS IG-2)
• Minutes of the RARS implementation Group Meeting (pdf 28kb)
• RARS Implementation Approach
• Timeliness of RARS Data at Tokyo