物理海洋学名词-V 450

Glossary of Physical Oceanography and Related Disciplines

Steven K. Baum Department of Oceanography Texas A&M University

May 26, 2004

 

vertical diffusivity An elusive quantity to obtain for the ocean. Indirect and direct (e.g. via the release and measurement of inert tracers) measurements show that mixing across density surfaces within the thermocline is on the order of ∼ 10^−5m2s−1. This is about a tenth of the value predicted by most ocean circulation models. The discrepancy is thought to be due to intense localized mixing at the boundaries, especially around sea mounts, i.e. topographically induced mixing. See Munk [1968] and Munk and Wunsch [1998].


virtual potential temperature A temperature defined to include the buoyant effects of liquid water in the air. It is calculated identically to the virtual temperature.


virtual temperature The temperature a sample of dry air at pressure P would have in order that its density equal that of the sample of moist air at temperature T , pressure P , and water vapor mixing ratio r. It is given by
T_v= T (1 + 0.6078 r).
a If there is also liquid water in the air this is modified as
T_v= T (1 + 0.6078 r − r_L)
where r_L is the liquid water mixing ratio (in grams of liquid water per gram of dry air). The virtual temperature is thus defined because it allows the ideal gas law to be used for situations in which the air is not dry, i.e. moist air of temperature T behaves identically to dry air of temperature T_v.

 

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