The object of EARS-ATOVS is to provide the European meteorological community with sounder data covering data-sparse areas, within 30 minutes of the instrument observations.

EARS comprises three separate polar satellite instrument data services — the existing EARS-ATOVS; the EARS-AVHRR and the pilot EARS-ASCAT. Each of the EARS services retransmits observations from an instrument, or an instrument group, and aims to provide a homogeneous service across the NOAA and Metop polar orbiting satellite platforms.

Traditionally, polar satellite data from the NOAA satellites has been received via two methods:

• the once per orbit data download from the spacecraft to the central NOAA ground station;
• 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. EARS 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.

The figure below illustrates this using the example of the current EARS-ATOVS service.

System Overview

The satellites and instruments supported by the EARS are as follows:

Network of HRPT/AHRPT Stations

The aim of the EARS has been achieved through the close cooperation of organisations willing to operate the network of HRPT stations. A major consideration has been to optimise the area of data coverage and to reduce system costs by making use of existing stations.

The network of HRPT/AHRPT stations acquires and processes the Metop and NOAA satellite HRPT/AHRPT telemetry data and forwards the generated meteorological products to EUMETSAT. These products are then disseminated to the users via EUMETCast and the RMDCN/GTS.

The relationship between the system elements making up EARS is shown in Figure 1.

The following organisations provide the HRPT network:

• Centre de Meteorologie Spatiale — Meteo-France (CMS)
• Danish Meteorological Institute (DMI)
• Hellenic National Meteorological Service (HNMS)
• Kongsberg Satellite Services (KSAT)
• Environment Canada/Environnement Canada (EC)
• National Oceanic and Atmospheric Administration (NOAA)
• National Institute for Aerospace Technologies (INTA)
• Roshydromet — SRC Planeta

All these organisations currently receive HRPT data. The station locations contributing to EARS are given in the table below.

Station Name	Country	Operated by	Location (lat, long)	Pictures
Gander	Canada	Environment Canada	48.94°N, 54.57°W
Edmonton			53.33°N, 113.5°W
Gilmore Creek (Alaska)	USA	National Oceanic and Atmospheric Administration (NOAA)	64.97°N, 147.40°W	1 | 2 | 3
Monterey			36.35°N, 121.55°W
Wallops Island			37.8°N, 75.3°W
Ewa Beach			21.33°N, 158.07°W
Miami			25.74°N, 80.16°W
Lannion	France	Centre de Meteorologie Spatiale	48.7°N, 3.5°W
Saint-Denis (La Réunion)			20.91°S, 55.50°E
Maspalomas	Spain	Instituto Nacional de Technica Aerospacial (INTA)	27.78°N, 15.63°W	1
Kangerlussuaq	Greenland	DMI	66.98°N, 50.67°W	1
Svalbard	Norway	Kongsberg Satellite Services (KSAT)	78.13°N, 15.23°E	1 | 2
Athens	Greece	Hellenic National Meteorological Service (HNMS)	37.815°N, 23.769°E	1
Moscow	Russian Federation	Roshydromet	55.759°N, 37.569°E
Muscat	Sultanate of Oman	Directorate General of Civil Aviation and Meteorology (DGMAN)	23.59°N, 58.29°E

Note: Investigations into the failure of the Metop-A AHRPT side A concluded that the root cause was heavy ion radiation causing the failure of a component of the AHRPT Solid State Power Amplifier (SSPA). To minimise the risk of failure of the Metop-A AHRPT-B unit, whilst still offering the User community a service, EUMETSAT has implemented a 'partial' AHRPT service in those areas where the risk of damage from heavy ion radiation is reduced. For southbound passes, AHRPT side B is activated for all orbits over the North Atlantic and European area, starting at around 60°N. The AHRPT is then switched-off before the spacecraft reaches the Southern Atlantic Anomaly region, at around 10°N. The switch-on of the AHRPT service for the descending passes over Europe and North Atlantic region allows ATOVS and AVHRR data to be available from the EARS network of stations.

To complement the partial Metop-A AHRPT-B service, a Fast Dump Extract service has been implemented. This service utilises the most recent part of the X-band global dump, received at Svalbard from the northbound passes. The ASCAT, ATOVS and AVHRR data streams can, thus, be provided with high timeliness for regional data, and are made available via the EUMETCast-Europe service.

Development Milestones