Baltic Sea

Date 31.8.1997, 03.11.1997, 03.11.1997, 17.2.1998, 17.2.1998, 18.2.1998, 27.3.1998, 21.4.1998,
UTC 21:12h 07:31h 08:52h 18:07h 20:49h 07:09h 01:20h 14:57h
〈R ρ〉 0.044 0.060 0.059 0.220 0.221 0.238 0.164 0.184
Std Dev 〈R ρ〉 1.219 0.032 0.035 0.133 0.165 0.116 0.458 0.090
〈T u〉 −47.49 −48.45 −48.39 −57.38 −57.44 −58.39 −54.30 −54.45
Table 3.2: Vertical averaged density ratio 〈R ρ 〉 with the standard deviation (Std Dev) and vertically
averaged Turner angles 〈Tu〉 of BMP271 between 170- 235 m for proles shown in Fig. 3.8.
Figure 3.9: Sketch of salinity/ heat budget calculations in the EGB for proles in shown Fig. 3.10.
that diusive convection essentially controls the diapycnal mixing within intermediate layers
(90-170 m), especially in the wake of deep warm-water intrusions reaching the EGB.
3.2.4 Salinity and heat budgets
Estimates for the eective diusivities in the deepest layers of the EGB may be obtained from
basin-scale scalar budgets as suggested e.g. for the Baltic Sea by Stigebrandt (1987) and
Axell (1998), as well as for some semi-enclosed deep basins o the Californian coast by
Ledwell and Hickey (1995).
Here, the starting point is selected to be the salinity budget for a xed control volume, V ,
underneath a level surface, A t , located at the vertical position z = z t ,
d
dt
∫
V
∫
∫
S dV = − Sw dA −
A t
A t
F S dA , (3.3)
where w and F S denote the vertical (upward) components of the velocity and the turbulent
salt ux, respectively. The only assumption involved in the derivation of (3.3) is the absence of
37