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Geothermal heating and the properties of bottom water in Cascadia Basin
Author(s) -
Hautala Susan L.,
Johnson H. Paul,
Bjorklund Tor
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl022342
Subject(s) - geology , bottom water , water mass , seafloor spreading , geothermal gradient , antarctic bottom water , temperature salinity diagrams , circumpolar deep water , oceanography , boundary current , petrology , geophysics , ocean current , salinity , deep water , north atlantic deep water
A new compilation of CTD data sheds light on the circulation and properties of bottom water within Cascadia Basin. A relatively high salinity water mass is revealed in a region of likely bottom water inflow east of the Blanco Fracture Zone. Water mass distributions and the deep geostrophic shear field are consistent with a general cyclonic circulation within the basin and suggest a northward‐flowing boundary current next to the deep continental slope. Shifts in temperature‐salinity relationships are consistent with a vertical transition from waters of northern origin to waters of southern origin approaching the seafloor. This vertical water‐mass transition complicates the interpretation of temperature anomalies. We redefine the temperature anomaly due to geothermal activity and the thickness of the layer influenced by seafloor heating. Simple heat budget calculations lead to a residence time of about one year for the bottom water, shorter than suggested by previous studies.