Process study is the phenomenological approach used in climatology. Process studies are used "to develop the parameterizations [e.g. of circulation models], and observations [are] used to calibrate [the latter]". A parametrization is a set of fitted equations to represent physical phenomena instead of deducing them from first principals. An example for a parametrized phenomenon are thunderstorms which cannot be simulated within a circulation model if the spatial resolution of several km is too coarse to resolve single storm cell.
Other meanings
There is a journal entitled Process Studies.
References
Cronin, Meghan F.; Legg, Sonya; Zuidema, Paquita (1 July 2009). "Climate Research: Best Practices For Process Studies". Bulletin of the American Meteorological Society. 90 (7): 917–918. Bibcode:2009BAMS...90..917C. doi:10.1175/2009BAMS2622.1. /wiki/Sonya_Legg ↩