Field Definitions are Available Here
Collection
string (500)
Keyword used to describe the science parameter area of the collection. A collection can conceivably cover many such parameters.
ATMOSPHERIC RADIATION
/ScienceKeywords/ScienceKeyword/TermKeyword
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString
Temporal Information (ECHO)