Current Service Announcement: Nil Current.

• The Australian Contribution to RARS
  • Coverage
  • Processing Software
  • Timeliness
  • Availability
  • Distribution mechanism
  • File naming and structure
  • Obtaining AP-RARS
• Scheduling Strategy
• Quality monitoring
• Service News
• Useful Links
  
  
  

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, 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/ (Register here first if you have not already done so)

Target timeliness of the service

The Australian RARS service is capable of delivering >95% data within 30 minutes from the start of the ingest from all ingest sites except Casey. Since Casey is situated on the Antarctic Continent, there is a limited bandwidth available for data transfer. Data from Casey should be available approximately 60 minutes from the start of the ingest. Note that for Davis, the HRPT file has the AVHRR set to zero and the file is transmitted over the limited bandwith more efficiently making it available within 30 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

The RARS filename and data formats are expected to change by March 2009.  In this section, we provide information on the new formats, followed by the existing format which is to be replaced.

Introduction

In order to make AP-RARS data more widely available and accessible, changes are required to the filename and data formats currently in use by AP-RARS participants.  Following agreements made at the International TOVS Study Conference (ITSC) and WMO RARS-IG-2 meetings in May 2008, these notes describe the required changes, and suggest an implementation timeframe.

These notes refer to a number of WMO documents and it is hoped that these references will suffice to enable AP-RARS participants to make the necessary changes.  The WMO documents should be treated as more authoritative than this document and other resources.

The required changes are as follows:

1. RARS filenames are to begin with ‘W…’;
   
   
2. the second ‘.l1c’ is to be dropped from the AAPP filename;
   
   
3. addition of a GTS bulletin header to BUFR bulletins (i.e. the RARS ‘files’):
   
   
   • for those sites not already creating headers, a script has been provided by Nigel Atkinson to do this (please see the ‘Other Resources’ section below for contact information); and
     
     
   • definition of the ‘A1A2’ field in the GTS bulletin header;
     
     
4. definition of ‘centre’ and ‘sub-centre’ identifiers for the BUFR bulletins (not in the bulletin header).

Diagrammatically, these changes can be represented as follows:

The most concise and authoritative summary of the changes is available at:
http://www.wmo.int/pages/prog/sat/RARS.html (follow the link to ‘RARS data coding summary’).

Further details are available at:
http://www.wmo.int/pages/prog/sat/RARS_data_quality_monitoring.html
Follow the link to the ‘Operator Standards’ Document.

Sample Filenames

As an example, a new filename would be:

           W_au-BOM-melbourne,HIRS,RARS+NOAA17+mel_C_AMMC_20061102225012_(AAPP filename)_bufr.bin

but with the trailing .l1c removed from the AAPP filename.

For example, if the output filename from AAPP was:

            hirsl1c_noaa17_20061102_2223_22652.l1c

the new filename would be

           W_au-BOM-melbourne,HIRS,RARS+NOAA17+mel_C_AMMC_20061102225012 _hirsl1c_noaa17_20061102_2223_22652_bufr.bin

For the same file, the name generated under the previous format would be:

           Z_RARS_C_AMMC_20061102225012_Rmel_hirsl1c_noaa17_20061102_2223_22652_l1c_bufr.bin

Note that the leading ‘RARS’ and satellite ID (e.g. ‘RARS+NOAA17’) are in upper case; this may not be clear from the WMO documents linked to above.

Examples of filenames from various RARS sites are detailed here. We believe they are correct, but please notify us of any errors or omissions. Some sample files can also be found on the Bureau's anonymous ftp site at:

ftp://ftp.bom.gov.au/anon/home/sat/RARS/

Proposed Timeline

It is requested that all AP-RARS receiving station operators adopt the new filename format, GTS bulletin headers and metadata by 5 March 2009 (to be confirmed at RARS-IG-3, 5-6 Feb 2009).

Other Resources

Further explanation of the changes and a helpful script are available on request from the AP-RARS coordinator, Anthony Rea (a.rea@bom.gov.au), or Gary Weymouth (g.weymouth@bom.gov.au).

Currently, the format (to be replaced) for the Asia-Pacific RARS is outlined below:

The generic filename is:

Z_RARS_C_CCCC_yyyyMMddhhmmss_Rrrr_AAPP filename_bufr.bin

where:

• 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(_).

Note that rrr is agreed as lower case, that hhmmss is the time of creation of the BUFR file, and that in the "AAPP filename" there is also a time stamp. However, the AAPP timestamp is for the reception of the first scan line in the NOAA data. Also please note that the "AAPP filename" is the filename as output by the latest version of AAPP - it has nothing to do with Eumetcast filenames.

The "AAPP filename" should be the filename as output by the latest version of AAPP, with the dot replaced by an underscore. An example of the AAPP output filename is:

hirsl1d_noaa17_20061102_2223_22652.l1d

which is derived in the form of:

INSTLEV SATIMG YYYYMMDD HHMN NNNNN.LEVEL

where (with the example in brackets after the explanation):

• 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)

As an example, if the output filename from AAPP was:

hirsl1c_noaa17_20061102_2223_22652.l1c

then the full RARS filename would be:

Z_RARS_C_AMMC_20061102225012_Rmel_hirsl1c_noaa17_20061102_2223_22652_l1c_bufr.bin

Obtaining AP-RARS

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

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

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 (Register here first if you have not already done so) (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 available via http://www.wmo.int/pages/prog/sat/RARS_data_quality_monitoring.html. 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). Timeliness 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
• Minutes of the 2^nd Session RARS implementation Group Meeting Geneva, 20-21 May 2008 (pdf 28kb)
• Minutes of the 1^st Session RARS implementation Group Meeting Geneva, 3-4 Jul 2007 (pdf 28kb)
• Timeliness of RARS Data at Tokyo