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EUMETSAT ATOVS Retransmission service (EARS) - Introduction

The aim of the EUMETSAT ATOVS Retransmission Service (EARS) is to provide sounder data from the National Oceanic and Atmospheric Administration (NOAA) satellites with a timeliness of 30 min., meeting requirements of European operational short range regional numerical weather prediction models.

Sounder data is produced by a set of the instruments known as ATOVS (Advanced TIROS Operational vertical Sounder), which are used to obtain information about the vertical profiles of temperature and humidity in the atmosphere. The radiation measurements from the ATOVS instruments can be assimilated directly in numerical atmospheric models using advanced techniques developed for operational use over the last decade. This vertical profile information is vital to the performance of all numerical forecasting model systems.
(A)TOVS data from the NOAA satellites has been received via two methods:

  • via the once per orbit data download from the spacecraft to the central NOAA ground station
  • via the direct transmission from the satellite to a High Resolution Picture Transmission (HRPT) station on ground

The first mechanism provides global coverage data to end users, but with delays of three to six hours after the time of measurement. The second mechanism provides the data virtually at the time of measurement, but the geographical coverage is limited to the region around the HRPT reception station. In addition the User needs to process the data himself, from raw data to calibrated instrument measurements.

The EUMETSAT ATOVS Retransmission Service provides improvements on both of these methods by offering a large geographical coverage combined with timely retransmission. This is achieved by establishing a network of existing HRPT stations around the Atlantic and Arctic Oceans and rapid distribution of the collected instrument data to end users.

System Overview

A network of HRPT stations acquires and processes the NOAA satellite HRPT telemetry data and forwards the generated meteorological products to EUMETSAT. EUMETSAT collects the products and disseminates them to the users via a commercial satellite broadcast service.

EARS makes use of the HRPT stations shown in the table below. Other stations may be added at a later time.
Station Name Country Operated by Location (lat, long)
Lannion France CMS 48.75°N, 3.47°W
Maspalomas (Canaries) Spain INTA/INSA 27.78°N, 15.63°W
Kangerlussuaq Greenland DMI 66.98°N, 50.67°W
Svalbard (Arctic) Norway KSAT 78.13°N, 15.23°E
Athens Greece HNMS 38.0°N, 23.44°E
Edmonton Canada MSC 53.50°N, 113.50°W
Gander (Newfoundland) Canada MSC 48.95°N, 54.55°W
Gilmore Creek (Alaska) USA NOAA 64.97°N, 147.40°W
Wallops Island (W Virginia) USA NOAA 37.85°N, 75.47°W
Monterey (California) USA NOAA 36.60°N, 121.89°W

Next figure shows an example for AMSU-B1 of the geographical coverage of successive NOAA16 acquisitions acquired at CMS within a 30 minutes delay.

Geographical coverage of successive NOAA16 acquisitions for AMSU-B1

Instruments and Data Processing

The instrumentation on the operational NOAA KLM series satellites includes the Advanced High Resolution Radiometer (AVHRR) and the Advanced TIROS Operational Vertical Sounders (ATOVS) consisting of the Advanced Microwave Sounding Units (AMSU-A/B) and the High Resolution Infrared Radiation Sounder (HIRS/3).

The EUMETSAT ATOVS Retransmission Service will collect ATOVS (AMSU-A/B and HIRS/3) and AVHRR data from operational NOAA satellites and process the data at the local station site. Products are then sent to EUMETSAT HQ and retransmitted.

AMSU-A, AMSU-B, HIRS/3 instrument data is provided in their original resolution. Cloud information derived from the AVHRR data is mapped onto the HIRS/3 instrument grid. The original AVHRR instrument data with a higher spatial resolution is not retransmitted.

The ATOVS and AVHRR Processing Package (AAPP) in its current version is used to process the instrument data. The AMSU-A, AMSU-B and HIRS/3 are retransmitted as both level 1a and 1c. Cloud information derived from the AVHRR data AVHRR is transmitted as level 1d mapped onto the HIRS/3 grid.

The products are disseminated over the broadcast service in compressed format, using bzip2.

Access to EARS

To access EARS, users need to establish a EUMETCast receiving station. For a detailed description of EUMETCast and information on receiving station requirements please consult the EUMETSAT EUMETCast page.

Furthermore, from 12 February 2003 the ATOVS data are also available via the GTS encoded in FM-94 BUFR.

Although the EARS data are be freely available, registration with the user service is required for these reception mechanisms.

Development Milestones

  • Broadcast Service Trials - February 2002 to mid July 2002
  • Development of the Service - December 2001 to October 2002
    This included establishing agreements with the HRPT stations, establishing the necessary communications network, establishing the broadcast service, development of the necessary hardware and software systems and deploying these at the HRPT station sites.
  • Start of Pilot Operational Service - November 2002
    Early operations of the service will only include a sub-set of the planned HRPT stations. The remaining HRPT stations and service support will be added during the first months of operation. Experience from the Pilot Operational Service will be gathered and used to assess the service, define improvements and consider possibility extension of the service.
  • End of Pilot Operational Service - end of 2004 (possibility to be extended)
  • Dec 2004 - End of Pilot EARS-ATOVS Service
  • Jan 2005 - Start of operational EARS-ATOVS Service
  • Dec 2005 - the EUMETSAT Council decided to continue and extend the existing EARS service for a period of four years. In addition to continuation of the ATOVS Retransmission Service, the EARS service was extended with the pilot ASCAT Retransmission Service and the pilot AVHRR Retransmission Service.
  • Jan 2005 - Oct 2005 - Preparation of Operational Service Specification for EARS-AVHRR & EARS-ASCAT
  • 14 March 2006 - Start of trial EARS-AVHRR service on EUMETCast Europe (Ku-band)
  • 10 May 2006 - Start of trial ERS-SCAT demonstration service as part of the preparations for the EARS-ASCAT Pilot service
  • 23 August 2006 - Start of EARS-ATOVS products dissemination from Lannion HRPT station
  • 18 October 2006 - Start of EARS-ATOVS products dissemination from Svalbard HRPT station
  • 2 April 2007 - Start of EARS-ATOVS products dissemination from Gander HRPT station

All ten HRPT providers are now online and provide data. The first operational use of EARS data has started.