. Collected reprints, Essa Institute for Oceanography. Oceanography 324 DONALD V. HANSEN AND MAURICE RATTRAY, JR. the flow ratio does not correlate well with stratification in estuaries and proposed in- stead a "stratification number" based upon tidal energy dissipation in the estuary. Our studies lead us to believe that no single parameter is adequate to portray the com- pound tendency of gravitational convec- tion to generate stratification and of vertical mixing from turbulent tidal currents to de- stroy it. The coupling between the circu- lation and salinity distrib
. Collected reprints, Essa Institute for Oceanography. Oceanography 324 DONALD V. HANSEN AND MAURICE RATTRAY, JR. the flow ratio does not correlate well with stratification in estuaries and proposed in- stead a "stratification number" based upon tidal energy dissipation in the estuary. Our studies lead us to believe that no single parameter is adequate to portray the com- pound tendency of gravitational convec- tion to generate stratification and of vertical mixing from turbulent tidal currents to de- stroy it. The coupling between the circu- lation and salinity distribution is included in the mathematical theory; the ratio P = Uf/Ut, proportional to the flow ratio, will be shown to be, within the limits of present data, a simple and adequate measure of the tidal mixing expressed by the theoretical tidal mixing parameter M/v. Fig. 3 shows the correlations obtained between these pairs of parameters for es- tuaries where observations can be inter- preted in terms of the theoretical models. The indicated straight-line relationships, not necessarily the best fit, are and vRa = 16F^ 3/4 M/v = '^/5 (5) (6) Considerable uncertainty attaches to values of vRa less than 100 because it is difficult to distinguish density effects from the in- fluence of boundaries on the velocity pro- file when the former are slight. The corre- lation of larger values of vRa with F^ is good. The greatest departures from the re- lationship between P and M/v are in the cases of the Mississippi River mouth where the theoretical models are inappropriate be- cause tidal currents are not the dominant cause of vertical mixing and of the Strait of Juan de Fuca wherein the salinity strati- fication is not strongly dependent upon local mixing conditions. Equations (5) and (6) can be combined with equations (1)-(4) from the theoretical models to compute the dependence of strat- ification and circulation on Fm and P in partially mixed and well-mixed estuaries. Fig. 4 shows the
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