Representing time varying data - suggestions for ontologies?

Suppose I want to say something like:

The total rainfall in Edinburgh in 2006 was 600mm.

There are various ways to do it, but I'd probably go for something  
like this in pseudo-RDF

Edinburgh  hasMeasuredProperty  _b
_b  measureOf  "Annual Rainfall"
_b  period  "2006"
_b  rdf:value  "600"
_b  unit  "mm"

(with some xsd data types added in).

The same general pattern applies to population of a country, or sales  
of a product etc. I'd expect this pattern of data to appear very  
frequently, but found it surprisingly difficult to find similar  
examples on the web (other than in the RDF Primer! - and the  
GoodRelations ontology does this kind of thing for  
PriceSpecification).  Can anyone suggest good ontologies/vocabularies  
I should consider in areas like socio-economic data, physical  
properties, weather, earth science that support this type of structure?

The NASA Jet Propulsion Lab SWEET ontologies seem relevant and are  
very comprehensive, if rather sparsely documented (http://sweet.jpl.nasa.gov/ontology/ 
). Anyone used those in anger?

Thanks for any tips

Bill