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Geographical grid systems

Definition:

Harmonised multi-resolution grid with a common point of origin and standardised location and size of grid cells.

Definition adopted by Workshop on “European Reference Grids”
A grid for representing thematic information is a system of regular and geo-referenced cells, with a specific shape and size, and an associated property.


Description:

Geographical grids are an agreed, defined and harmonised grid net for Pan-Europe with standardised location and size of grid cells. Examples of cell sizes could be 10x10 m, 100x100 m, 1x1 km, 16x16 km. A good candidate for the INSPIRE-focused Pan-European grid has been proposed as a result of the Workshop on “European Reference Grids”.

The grid – proposed as Pan_European standard – is based on the ETRS89 Lambert Azimuthal Equal Area coordinate reference system with the centre of the projection at the point N 52o, E 10o. The grid is defined as hierarchical one in metric coordinates in power of 10.

The detail description of the proposed grid is available at the Proceedings of the Workshop on the European Reference Grids, EUR Report 21494 EN, 2005. The Proposal for a European Grid System is presented from page 39 to 46 of that document.

Other grids could be also used, however they need a lot of harmonisation work, as well as a number of conversion tools. Some international organisations, like WMO, perform their operations, using their own and purpose-oriented grid construction.

Scope, use examples:

Several grid-based inventories exist in many European organisations and professional communities. Some of them have a long time series of observations and have a strong standardising impact to the methodology of data collection, analysis and reporting.

Some important grid systems are listed below. The list is not exhaustive. It may be completed in the process of review by SDICs and LMOs.

MEUSIS (Multiscale European Soil Information System) has been developed in the framework of the activities of the European Soil Bureau and involves national soil surveys and soil science institutions in more than 45 countries of Europe, Siberia and part of North Africa and the Middle East. The system is based on the Soil Geographical Database of Europe (SGDBE) at scale 1 : 1 000 000. The reference grid of the MEUSIS will be based on the grid proposed for INSPIRE.

EMEP is a scientifically based and policy driven program under the Convention on Long-range Transboundary Air Pollution for international co-operation to solve transboundary air pollution problems. The inventory of air pollution is based on the models, which are using a grid system of two resolutions: 50 km x 50 km and 150 km x 150 km. The grid is based on a polar-stereographic projection with real area at latitude N 60o and y-axis parallel to W 32o. The EMEP 50 consists of matrix of 132 x 111 points, whereas EMEP 150 domain includes 44 x 37 points.

AFE (Atlas Florae Europaeae) is a project for mapping the distribution of vascular plants in Europe. The project was launched already in 1965 as a collaborative effort of European botanists and since then the secretariat has functioned at the Botanical Museum of the Finnish Museum of Natural History, Helsinki.

The chorological data are inserted into the map with squares of c. 50 x 50 km, based on the Universal Transverse Mercator (UTM) projection and the Military Grid Reference System (MGRS). The Military Grid Reference System (MGRS) is an extension of the UTM system. UTM zone number and zone character are used to identify an area 6 degrees in east-west extent and 8 degrees in north-south extent. UTM zone number and designator are followed by 100 km square easting and northing identifiers. The system uses a set of alphabetic characters for the 100 km grid squares. Starting at the 180 degree meridian the characters A to Z (omitting I and O) are used for 18 degrees before starting over. From the equator north the characters A to V (omitting I and O) are used for 100 km squares, repeating every 2,000 km. Northing designators normally begin with 'A' at the equator for odd numbered UTM easting zones.

CGMS (Crop Growth Monitoring System) grid has been developed in the framework of MARS (Monitoring Agriculture with Remote Sensing) and was based on collection of meteorological and remote sensing data. The data were transformed and modelled into crop parameters. The grid is based on the Lambert Azimuthal Equal Area projection with the centre of projection at N 48o E 9o. and consists of 5625 cells of 50 km x 50 km each.

Point statistical and measurement (e.g. monitoring observations) data converted to the grid elements can be another area of a geographical grid system use. There are a number of practical implementation of the conversion, however there is no international standard in that scope.

Atmospheric and Oceanographic numerical forecasting or climate models have 4-dimensional grids which change relatively frequently (often on a yearly basis) as the models (and the supercomputers they run on) develop. Data from these models are exchanged under WMO data specification standards which include the definition of the exchange grid within the metadata included with the data. The definition and registration of these grids are excluded from the scope of this clause because they are highly mutable and can be specific to the data implementation. The WMO approved a general purpose, bit-oriented data exchange format, designated FM 92-VIII Ext. GRIB (GRIdded Binary). It is an efficient vehicle for transmitting large volumes of gridded data to automated centres over high-speed telecommunication lines using modern protocols. GRIB can equally well serve as a data storage format, generating the same efficiencies relative to information storage and retrieval devices.

National grid systems need also to be taken into account because the great amount of data that has been geo-referenced using them. Sometimes national grid systems has been based on the sheet distribution of the national topographic map. The possibility of national grid systems harmonisation should be considered, however it seems to be long term task.

Important feature types and attributes:

The feature types and attributes depend on the thematic data collected and maintained in the framework of the grid referencing systems. The most important spatial identifiers for the theme A 1.2 are code of grid cells, which has been described at the section “Description”, above.

The following feature and attributes may be relevant:

Grid cell (area, line, point)

  • Grid cell system identifier;
  • Grid cell system name;
  • Grid cell identifier;
  • Grid cell value.

Links and overlaps with other themes:

The main links and overlaps are where grids area being used to locate registration/monitoring sites, for aggregation of data from different topics and for display. Links and overlaps with INSPIRE themes are:

  • Orthoimagery;
  • Statistical units;
  • Soil;
  • Human health and safety;
  • Population distribution – demography;
  • Atmospheric conditions;
  • Meteorological geographical features;
  • Oceanographic geographical features;
  • Species distribution.

Reference documents:

http://www.emep.int/grid/griddescr.html

http://dataservice.eea.eu.int/dataservice/metadetails.asp?id=831

http://dataservice.eea.eu.int/dataservice/metadetails.asp?id=831

http://www.eumetsat.int/HOME/Main/Access_to_Data/Meteosat_Meteorological_Products/BUFR___GRIB2/index.htm?l=en

European Reference Grids. Proposal for a European Grid System. Workshop Proceedings and Recommendations. Edited by: Alessandro Annoni. JRC, Ispra, 27-29 October 2003. Institute for Environment and Sustainability, EUR Report 21494 EN, 2005.

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Last updated 2718 days ago by INSPIRE Forum