I would propose that each site that hosts a Catalog of Open Data Portals has a downloadable version of the catalog in CSV format. To ease exchangeability, I would recommend the following layout:
url, short name, formal name, political entity, admin division, category, license
url : Url to the open data portal
short name: A short name for the data portal (abbreviation, acronym, etc).
formal name: formal name of the open data portal (e.g., City of Madison Open Data ....)
political entity: country or dependency (e.g., Canada)
admin division: administrative division type (e.g., state, province, county, town,...)
category: type of open data portal. some examples:
- Data Portal (multi-category)
- Transparency Portal (government finances, budget, payroll, expenditure)
- GIS/Gazetteer (Geographic Information Systems, Maps)
- Census/Demographics (Population Statistics)
license: type of license to use the data. examples:
- CC0 (public)
- UK OGL
This level would add information for geolocation and geographic scope that the portal covers.
url, short name, formal name, political entity, admin division, category, license, coord, area
coord : lat/lng of area centroid
area : total area in sqkm
This should be fairly easy to looked up and added.
This level would add population scope that the portal covers.
url, short name, formal name, political entity, admin division, category, license, coord, area, pop, year
year: year of population statistic
This level would add information on the amount and scope of information in the data portal:
url, short name, formal name, political entity, admin division, category, license, coord, area, pop, year, ndatasets, nrecords, subcategories
ndatatsets : the (approx) number of datasets in the portal
nrecords : the (approx.) total number of data records in the portal.
subcategories: a list of subcategories of the type of data available (e.g., crime, bus routes, business licenses, etc).
This would take a crawler to periodically crawl the portal to determine size and scope.