The surface called "surface" means the lower boundary of the atmosphere. Downwelling radiation is radiation from above. It does not mean "net downward". The sign convention is that "upwelling" is positive upwards and "downwelling" is positive downwards. The term "shortwave" means shortwave radiation. Surface downwelling shortwave is the sum of direct and diffuse solar radiation incident on the surface, and is sometimes called "global radiation". When thought of as being incident on a surface, a radiative flux is sometimes called "irradiance". In addition, it is identical with the quantity measured by a cosine-collector light-meter and sometimes called "vector irradiance". In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.
This concept was harvested from the controlled vocabulary at http://vocab.nerc.ac.uk/collection/P07/current/ on 2022-06-10. Information was pulled as-is for the following properties: dcterms:created, skos:definition, skos:exactMatch, skos:related and skos:notation. The URI of the concept is generated using SHA256 on the CF standard name (in the skos:notation) and concatenated with the TERN controlled vocabularies' base URI (http://linked.data.gov.au/def/tern-cv/).
TERN is supported by the Australian Government through the National Collaborative Research Infrastructure Strategy, NCRIS.