Global geospatial data from Earth observation: status and issues

Figures & data

Table 1. Principle space agencies with missions collecting data for global data sets.

Agency	Country	No of missions	Principal instruments for global data sets
CNES	France	25	SPOT, Pléiades
DLR	Germany	10	SRTM X-Band, TanDEM X
ESA/EUMETSAT	Europe	44	GOME, MERIS, RA-2, AATRS, ASCAT, Sciamachy, Sentinel 1–6
JAXA/METI	Japan	12	ASTER, AVNIR, PRISM
NASA	USA	59	Landsat, MODIS, SRTM C-Band, Topex
NOAA	USA	41	AVHRR, GOES, Tiros

Table 2. Examples of sensors used to collect data for global data sets.

Sensor type	Sensor characteristics	Main examples	Global data sets
Land
MSS	Records energy received in discrete spectral bands in the visible, infrared and thermal infrared spectral bands	Landsat TM, MODIS, AVHRR, AATSR, MERIS, Sentinel 2	Land cover soils vegetation
HR optical	Records energy in the visible (panchromatic band) and in multispectral bands in the visible and NIR spectrum	SPOT, Pléiades, ASTER, PRISM	DEMs
Interferometric SAR	Record microwave energy from two or more positions and calculates phase difference	SRTM, TanDEM X, Sentinel 1	DEMs
Oceans
Microwave altimeter	Calculates range from microwave signals	Topex, RA-2, Sentinel 6^a	Ocean topography
MSS in visible and infrared	Records energy received in discrete spectral bands in the visible, infrared and thermal infrared spectral bands	MODIS, AVHRR	Sea surface temperature
Scatterometer	Scatterometers transmit a pulse of microwave energy towards the Earth’s surface and measure the reflected energy	ASCAT, Sentinel 3	Wind speed and direction, soil moisture, sea ice cover, sea ice type, snow cover, vegetation parameters
Atmosphere
Spectrometers	Records the intensity of light as a function of wavelength or of frequency	GOME, Sciamachy	Ozone
Atmospheric chemistry		Sentinel 4^a and 5^a	Air quality
Visible, IR	See MSS	Tiros, GOES	Cloud

^aSentinel 4–6 are planned for the future.

Figure 1. Frequency of commercial acquisitions in 2015 (Geocento 2016).

Table 3. Examples of portals serving global data sets.

CEOP	Coordinated Enhanced Observing Period http://www.eol.ucar.edu/field_projects/ceop
ESA	European Space Agency and Copernicus Sentinel data hub: https://scihub.copernicus.eu ESA Earth Online: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/envisat
GCMD	Global Change Master Directory http://gcmd.gsfc.nasa.gov
GISD	Geographic Information for Sustainable Development
GOFC	Global Observation of Forest Cover Development http://www.fao.org/gtos/gofc-gold/portal/portal_1.html
Human Health and Disease Data Portal
Human Health and Disease Data Services Portal
JAXA	Japan Aerospace eXploration Agency https://www.gportal.jaxa.jp/gp/top.html
NASA, EOSDIS, DAACS	Earth Observing System Data and Information Archive Centers http://reverb.echo.nasa.gov/reverb/#utf8=?&spatial_map=satellite&spatial_type=rectangle
NOAA	National Oceanic and Atmospheric Administration Comprehensive Large Array-data Stewardship System (CLASS): http://www.class.ncdc.noaa.gov/saa/products/welcome;jsessionid=FF4EA1BCF9B5EBF7A81B69F977DA86A7 NOAA NODC AVHRR Pathfinder Project: http://www.nodc.noaa.gov/SatelliteData/pathfinder4km/
UN	United Nations Earth Science Data
WWF	World Water Forum
GEOSS	Portal connects users to existing databases and portals which have registered with the GEOSS portal http://www.geoportal.org/web/guest/geo_home_stp
Esri	Provides data sets for use with ArcGIS http://www.esri.com/software/arcgis/arcgisonline http://opendata.arcgis.com/
Worldgrids	1 km environmental layers in a standardised format http://www.worldGrids.org

Figure 2. The GEOSS portal architecture which allows users to connect to existing data sets.

Table 4. Organisations processing EO data to create global data sets.

Organisation and url	Description and examples
Joint Research Centre of the European Union https://ec.europa.eu/jrc/	The Institute for Environment and Sustainability provides scientific and technical support to EU policies for the protection of the environment at global and continental scales and distributes a range of data from EO. Data includes forestry, marine, soil and biophysical parameters
CIESIN (Center for International Earth Science Information Network) www.ciesin.org	CIESIN specialises in on-line data and information management, spatial data integration and training, and interdisciplinary research related to human interactions in the environment. Data includes population, agriculture, natural hazards
FAO’s Data Portal http://www.fao.org/geonetwork/srv/en/main.home	Serves a diversity of data produced by FAO run or supported projects at a diversity of scales and includes agriculture and livestock, applied ecology, climate, fisheries and aquaculture, forestry, human health, hydrology and water resources, land cover and land use, population and socio-economic indicators, soils
UNEP/GRID GEO DataPortal and UNEP/GRID-Arendal http://geodata.grid.unep.ch http://www.grida.no	A large repository of global grids at various resolutions and includes freshwater, population, forests, emissions, climate, disasters, health and GDP
Environmental Information Portal of the World Resources Institute http://earthtrends.wri.org/resources/data_sets	Contains a number of global grids derived by the WRI and collaborators including water, climate and energy
Google Earth Engine https://earthengine.google.com	Google Earth Engine provides access science raster data sets, including Landsat, Sentinel, MODIS collections, geophysical demographic and climate and weather data
ISCGM (International Steering Committee for Global Mapping) http://www.iscgm.org	Provides access to the ISCGM global map as well as other data sets

Table 5. The evolution of global DEMs (compiled from several sources).

Year	Name	Spacing	Vertical accuracy	Source	Comment
1960–1990	DCW		Heights from 1000’ contours	World navigation charts	Better models now available
1988	ETOPO5	10/5′	Variable	Various	USGS
1996	GTOPO30	30″	25 m	Mainly DTED	USGS
1999	GLOBE	30″	Variable	DTED and SPOT
2000	SRTM	30 m/90 m	10–15 m	Shuttle IfSAR	56°N to 60°S
2009–2011	ASTER GDEM	30 m	7–14 m	ASTER	Gaps filled with SRTM
2014	WorldDEM	12 m	2 m (rel) 4 m (abs)	TanDEM-X	DSM and DTM commercially available at cost
2016	ALOS World 3D	30 m	5 m	ALOS PRISM	Freely available and based on 5 m global DEM which is available commercially at cost
2016	Vricon			DigitalGlobe sensors	DSM and DTM commercially available at cost

Note: GDEM, global digital elevation map.

Table 6. Accuracy of SRTM DEM determined from ground truth. All quantities represent 90% errors in meters.

	Africa [m]	Australia [m]	Eurasia [m]	Islands [m]	N America [m]	S America [m]
Absolute geolocation error	11.9	7.2	8.8	9.0	12.6	9.0
Absolute height error	5.6	6.0	6.2	8.0	9.0	6.2
Relative height error	9.8	4.7	8.7	6.2	7.0	5.5
Long wavelength height error	3.1	6.0	2.6	3.7	4.0	4.9

Figure 3. Growth of data volume from ENVISAT ASAR to Sentinel-1 (Wagner 2015).

Geocento. 2016. “Satellite Image Acquisitions in 2015.” Accessed July 2016. http://geocento.com/satellite-images-acquisitions-in-2015/#.VpisxjbHTzJ.

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Wagner, W. 2015. “Big Data Infrastructures for Processing Sentinel Data.” In Photogrammetric Week 2015, edited by D. Fritsch, 93–104. Berlin: Wichmann.

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