Global Data Service

The Global Data Service provides near real-time products to the user community generated from instrument data.

Overview of Data Dumps via Svalbard and McMurdo Station

Instrument data recorded during the last orbit of Metop are dumped to the Central Data Acquisition Station (CDA) located in Svalbard and the Antarctic Data Acquisition service (ADA) at McMurdo Station, Antarctica.

  • GDS Metop-A: Current service provided by the Metop-A low Earth orbit polar satellite providing Global Data Service data acquired from the mid-morning orbit.
  • GDS Metop-B: Current service provided by the Metop-B low Earth orbit polar satellite providing Global Data Service data acquired from the mid-morning orbit. The Metop-B orbit is phase separated from Metop-A by 180°.
  • GDS S-NPP: The Suomi-National Polar Orbiting Partnership (S-NPP) satellite provides Global Data Service data as NOAA's prime Services Mission for the afternoon orbit.
  • GDS NOAA: Low Earth orbit polar satellite service which complements the GDS s-NPP services, providing data acquired from the afternoon orbit.

The data received at the CDA and ADA is transferred to the Central Facility, located in EUMETSAT headquarters, where they are processed for onward distribution to the user. AVHRR and ATOVS global data products, originating from the NOAA spacecraft, are also generated within the Central Facility.

Global Data Service — Suomi NPP

Data Delivery Timeliness

Antarctic Data Acquisition service

The addition of the Antarctic Data Acquisition service, for the prime satellite Metop-B, has halved the data transfer from satellite to ground station. Close to 14 orbits include ADA dumps. The average timeliness of products extracted from Metop-B data has improved, on average, from 59 minutes to 47 minutes.

McMurdo Station hosts the McMurdo Ground Station (MGS), which acquires the Metop satellite descending orbit global data dumps, while the NOAA-NSF McMurdo Multi-mission Communications System (MMCS) transfers the data from Antarctica to EUMETSAT’s Operations Control Centre in Darmstadt.

Upon reception at EUMETSAT, the McMurdo acquired half-orbit is immediately processed and disseminated to users, and subsequently complemented with the second-half (ascending) orbit acquired at Metop’s existing primary ground station in Svalbard, thereby ensuring improved timeliness in the delivery of data measured throughout the Metop orbit.

Svalbard Transfer Speed Increases

In 2013, following the successful launch of Metop-B, enhancements were made to the transfer speed on the fibre link between Svalbard and Darmstadt. As a result, the average timeliness has also significantly improved for the non-ADA supported passes of Metop-A and NOAA-19.

Average timeliness of level 1 products extracted from Metop-A and NOAA-19 data — acquired only at Svalbard — has improved from 101 minutes to 82 minutes and from 85 minutes to 72 minutes, from sensing.

Product Processing

Global data products are categorised according to instrument and product level. Definition of the different product levels:

  • Level 0: Raw data after restoration of the chronological data sequence for each instrument, i.e. after demultiplexing of the data by instrument, removal of any data overlap due to the data dump procedure and relevant quality checks. Raw instrument data information (telemetry packets) is maintained during this process.
  • Level 1a: Instrument data in full resolution with radiometric and geometric (i.e. Earth location) calibration computed and appended but not applied.
  • Level 1b: Calibrated, Earth located and quality controlled product, in the original pixel location, and packaged with needed ancillary, engineering and auxiliary data.
  • Level 1c: In case of the IASI spectra, level 1b data after application of the apodization function.
  • Level 2: Earth located values converted to geophysical parameters, at the same spatial and temporal sampling as the level 1b and 1c data.
  • Level 3: Gridded point geophysical products on a multi-pass basis, or resampled products (applicable for some Satellite Application Facility (SAF) products).

For further information, see EPS Generic Product Format Specification (PDF, 738 KB).

Data granules generated for dissemination are Product Dissemination Units (PDUs), containing about three minutes of instrument-specific observation data. PDUs are independent, self-standing entities, i.e., not just slices of a full orbit product. The timeliness requirement for PDUs is 2 hours 15 mins (delta between sensing and reception at a EUMETCast station) for Level 1 products, and three hours for Level 2 products. PDUs are disseminated in the EPS native format and/or in BUFR format, depending on the instrument and processing level.

EPS Native Format and BUFR Format — PDUs in EPS native format are structured in sections:

  • Header Section — providing general data.
  • Pointer Section — allowing navigation within the product file.
  • Global Aux Data Section — defining data used in the processing for the entire product.
  • Variable Aux Data Section — defining data used in the processing for part of the product.
  • Body Section — containing the measurement data itself.

Product Overview

ATOVS and AVHRR

ATOVS and AVHRR have a wide range of applications — cloud and precipitation monitoring; sea ice and snow cover detection, and surface temperature determination — as well as supplementing the retrieval of vertical temperature and humidity profiles.

GRAS

GRAS provides a minimum of 500 stratospheric and tropospheric temperature and humidity profiles, per day, by a process of GPS radio occultation, as well as the ionosphere total electron content. It also provides navigation solutions of the Metop satellite position along its orbit.

IASI

IASI provides highly detailed global measurements of atmospheric temperature and water vapour, making it possible to ascertain temperature and humidity profiles with a vertical resolution of 1 km, accurate to 1°C and 10% respectively, and a horizontal sampling of 20 km.

GOME-2

GOME-2 measures profiles and total columns of ozone, and other atmospheric constituents that are related to the depletion of ozone in the stratosphere and its production in the troposphere and natural and anthropogenic sources of pollution. Long-time series of ozone and water vapour total columns retrieved by GOME-2 will also significantly improve our capability of medium and long-term climate forecasting and modelling.

ASCAT

ASCAT measures wind speed and direction over the oceans. The main operational application is the assimilation of ocean winds in NWP models. Other operational applications, based on the use of measurements of the backscattering coefficient, are sea ice edge detection and monitoring, monitoring sea ice, snow cover and land surface parameters.

For the full list of global products and further information on their availability, please consult the Product Navigator.

Service Registration

Access to the data and products typically involves an initial registration process. For further information, please visit our Data Registration page, or register on the Earth Observation Portal (EOP).