https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 23.7 2026-04-15T10:53:30.610Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/sciencekeywords/08240c92-00b5-4f25-bf2e-8030531a78d2 PERMAFROST Date=2024-09-26 User Id=tstevens Entity=WeightedRelation Operation=INSERT System Note=insert WeightedRelation New Value=id: null related concept uuid: fb3ce3be-d830-407f-bd7c-58d66c24b6be relationship type: null relationship value: null generated by: null Date=2021-08-27 User Id=tstevens Entity=Definition Operation=UPDATE Field=reference System Note=update Definition Old Value=The Nature and Properties of Soils, Prentice Hall, 1996. New Value=American Meteorological Society Glossary of Meteorology Date=2021-08-27 User Id=tstevens Entity=Definition Operation=UPDATE Field=text System Note=update Definition Old Value=Permanently frozen material underlying the solum. New Value=A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years. A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years. 2024-09-26 15:04:36.0