Digital Earth Africa is entirely dependent on what is called Analysis Ready Data (ARD), which is Earth observation data that has been processed according to a set of requirements that allow immediate analysis. Currently, we take open and free ARD provided by international satellite programs, including;

And make them available through the DE Africa platform as Cloud Optimised GeoTIFFs with SpatioTemporal Asset Catalog (STAC) metadata. These datsets are provided with the intent and expectation of meeting the Committee on Earth Observing Satellites (CEOS) ARD specifications. The CEOS has been developing ARD specifications since 2016 to allow data to be processed to a more accessible and interoperable level. We use these datasets to create our data products, but we also make the datasets themselves available through the DE Africa platform.

DE Africa uses these datasets to create products and services at continental scale. By providing the data in a more accessible format, a larger range of non-specialist users will be able use its valuable information and insights. From simply identifying water resources for greater access to clean water through to the ability to regularly map food crops.

The Committee on Earth Observing Satellites (CEOS) ensures international coordination of Earth Observation programs and promotes exchange and optimisation of data for decision making. CEOS Analysis Ready Data for Land (CARD4L) Earth observation data has been processed to a minimum set of requirements and organised into a form that allows immediate analysis with minimum of additional user effort. CARD4L also provides a level of interoperability, both through time and space and with other datasets. In 2019, after several years of development, CEOS released Specifications for Land Surface Reflectance, Surface Temperature, and Normalized Radar Backscatter.

Preparing data for analysis is a major hurdle to uptake of satellite images. Traditionally 80% of project time could be taken up in accessing, pre-processing and organising satellite images. Analysis ready data is a game-changer and is critical if Earth observation infrastructures are going to be efficient, and sustainable. CARD4L Specifications are community-developed specifications for the necessary processing and metadata.

Digital Earth Africa (DE Africa) will host satellite data that meets the CARD4L Specifications. Landsat Collection-2 are the first datasets to listed as CARD4L compliant. Collection-2 is providing the fundamental starting point for DE Africa and is expected to be the basis for many of the information products and services to be developed in the Establishment phase. Other crucial data sources are Sentinel-2, which provides more frequent and higher spatial resolution observations from 2017 onwards, and Sentinel-1, a radar mission of particular importance in areas where there is persistent cloud cover.

Ensuring CARD4L-compliance is essential to the sustainability of DE Africa. DE Africa will work with satellite operators and encourage their efforts to routinely observe Africa, and to operationalise CARD4L-compliant data. This improves the sustainability of the DE Africa Program by removing the burden of producing and maintaining bespoke approaches to data processing. It also ensures that datasets are processed consistently and are compatible with global datasets.

To find out more about Analysis Ready Data and what it means for DE Africa, check out the following resources:

This seamless cloud-free image of South Africa, looking north over Namibia and Botswana, is in fact the median of hundreds of images taken throughout 2018. This processing is possible because the source Landsat images are processed to CEOS Analysis Ready Data Specifications.

seamless cloud-free image of South Africa, looking north over Namibia and Botswana