Overview of Data Dumps via Svalbard and McMurdo Station. (Click to enlarge)

The Global Data Service provides near real-time products to the user community generated from instrument data. Instrument data recorded during the last orbit of Metop are dumped to the Central Data Acquisition Station (CDA) located in Svalbard. The service will expand in coming years, when the Antarctic Data Acquisition service becomes fully operational.

The data received at the CDA and ADA is transferred to the Central Facility (CF), 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 CAF.

Improving Data Delivery Timeliness

With the addition of the Antarctic Data Acquisition service (based at McMurdo Station, Antarctica), Metop meteorological and environmental data are delivered, approximately, twice as fast as they currently receive it, by reducing the amount of time that meteorological sensor data stored on the satellite’s on-board recorders must wait before being downlinked to the ground for processing. The service is currently in its demonstration phase.

McMurdo Station hosts the recently refurbished NASA MG-1 ground station, which acquires the Metop satellite descending orbit global data dumps, while the new NOAA-NSF McMurdo Multi-mission Communications System (MMCS) transfers  the data from Antarctica to EUMETSAT’s Operations Control Centre in Darmstadt, Germany. 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.

The demonstration phase is foreseen to last until early 2014, during which Metop-A will average at least nine data dumps per day over McMurdo, in addition to the 14 dumps currently acquired by the Svalbard ground station. Whereas Metop-A level 1 products, based on data downlinked from both the McMurdo and Svalbard stations, achieved a timeliness of around 65 minutes, those from data downlinked only at Svalbard retained the current timeliness of approximately 115 minutes.

From 2014, it is foreseen that McMurdo MG1 shall be available for reception of all Metop orbits.

Product Processing

Global data products are categorised according to instrument and product level. The following is a definition of the different product levels, as understood in the EPS context:

• 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.

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

The Advanced TIROS Operational Sounder (ATOVS) instruments (AMSU-A, HIRS and MHS), in combination with the Advanced Very High Resolution Radiometer (AVHRR), covers the visible, infrared and microwave spectral regions and, thus, has 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

The GNSS (Global Navigation Satellite System) Receiver for Atmospheric Sounding (GRAS), uses a new method for providing temperature and humidity profiles for assimilation in NWP models. It is a GPS (Global Positioning Satellite) receiver that operates as an atmospheric-sounding instrument. 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. In addition, GRAS provides navigation solutions of the Metop satellite position along its orbit.

IASI

The Infrared Atmospheric Sounding Interferometer (IASI), represents a significant advance in the quality of the measurements injected into models, for understanding and making atmospheric forecasts. It rests on instrumental physics, and particularly innovative technologies, for a completely new European contribution to polar meteorology. 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

The depletion of the atmosphere's protective ozone layer is of particular environmental concern. It is particularly noticeable over the Arctic and Antarctic regions. The resulting increased levels of ultraviolet radiation are having harmful effects on agriculture, forests and water ecosystems and people. The Global Ozone Monitoring Experiment-2 (GOME-2), spectrometer measures profiles and total columns of ozone, and of other atmospheric constituents that are related to the depletion of ozone in the stratosphere and its production in the troposphere, as well as to natural and anthropogenic sources of pollution. Long-term monitoring of tropospheric pollutants will provide more insight into the impact of anthropogenic sources of pollution on climate and air quality.

The amount of ozone and water vapour in the atmosphere determines, to a large part, the atmospheric radiative forcing. Near real time use of retrieved ozone profile information in NWP models can significantly improve the modelling of the radiation balance, and the description of the lower stratospheric wind, and, therefore, the quality of the meteorological forecast. 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

The Advanced SCATterometer (ASCAT), is the enhanced follow-on instrument to the highly successful scatterometers flown on ESA's ERS-1 and ERS-2 satellites. The prime objective of ASCAT is to measure 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. The most important benefits of ASCAT will be in weather forecasting and climate monitoring by helping to improve the definition of the atmospheric circulation in the tropics and on the sub-synoptic scales.

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