Improve IceField definitions and linkage

[rduerr]

There are 4 definitions for ice field in cryospheric science:

1. In the sea ice nomenclature, an ice field is an area of floating ice consisting of any size of floes, which is greater than 10 km across.

2. In glaciology, an ice field is a continuous accumulation of snow and glacier ice that completely fills a mountain basin or covers a low-relief mountain plateau to a substantial depth. When the thickness become great enough, tongues of ice overflow the basins or plateaus as Valley Glaciers.

3. In physical geography, an ice field is a large level area of glacial ice found covering a large expanse of land. Similar in size to an ice cap but does not have a dome-shape.

4. A large ice body that covers mountainous terrain but is not thick enough to obscure all of the subsurface topography, its flow therefore not being predominantly radial as is that of an ice cap and usually smaller and lacking a dome-like shape; somewhat controlled by terrain.

The SWEET ontology only considers the sea ice version. What if any GCMD changes or SWEET changes are needed to optimize

[Garybc]

In SWEET there seems to be no ice field for glaciers, only sea ice.