Observation data are acquired and processed within the EPS-SG system. In order to distribute this data to end-users, a number of operational data delivery services have been defined.
Global Data Service
The instrument data will be provided to the users in near real-time, after their acquisition and processing by the ground segment to obtain geometrically consistent and calibrated radiance values, and a number of geophysical variables with global coverage. Processed data will be transmitted to users primarily via EUMETCast. Meteorological data and products will also be sent and relayed via the WMO Global Telecommunications System (GTS) and the Regional Meteorological Data Communication Network (RMDCN) to the National Meteorological Services and ECMWF.
The period between observation by the instrument and delivery of the data to the users, via EUMETCast, has a target timeliness of 70 minutes or better, depending on geographical location of the observations.
As a typical example of an instrument coverage pattern, Figure 2 below shows the global spatial coverage for the IAS mission after 24 hours, driven by the ground track of the satellite (shown as blue lines).
Figure 2: IAS Coverage with Metop-SG ground track
Regional Data Service
The regional data service uses a network of direct broadcast data receiving ground stations to rapidly transmit data from a defined geographical Area of Interest (AOI) to users. The baseline regional AOI currently covers the North Atlantic and European regions between 30° to 80° North and 65° West to 50° East, as shown as the red box in Figure 3.
The plan is to re-use selected existing EPS EARS direct broadcast station sites to cover the AOI and add complementary stations as necessary.
Data received at the stations is transmitted in real-time to EUMETSAT Headquarters for processing and transmission to end users via EUMETCast. AOI data will be delivered to users within 30 minutes of sensing, making it suitable for short range regional numerical weather prediction models.
Not every satellite orbit will be visible from the AOI. Over five days there will be 24 descending and 28 ascending passes over the AOI, i.e. about three-quarters of the orbits will have some degree of visibility over the AOI, either on their ascending or descending parts.
Direct Data Broadcast Service
Instrument data will be broadcast in real-time by the satellites to receiving stations in visibility of the satellite (direct broadcast). This transmission will be in X-Band and allow reception via an antenna of approximately three metres (depending on local conditions and quality of the antenna system) and a user station. Data is only available for the field of view of the satellite, but it is available in real-time, making it useful for nowcasting applications and short-range numerical weather prediction.
On-board generated instrument calibration data and administration messages will also be transmitted to users as part of the direct broadcast data.
The Space-to-Ground Interface Control Document (ICD) for Metop-SG defines the radio frequency and encoding characteristics of the satellite Direct Broadcast downlink, which is essential for the design of the Direct Broadcast reception station antenna, feed, demodulator and bit synchroniser. The Space-to-Ground ICD also defines the layout and content of the DB data stream, which is essential for defining the interface to the processing S/W packages processing the DB data stream to level 0.
Archive and Retrieval
The instrument data will be archived and be available for retrieval via the internet.