Dynamics of Coastal Models - Manejo Costero

Examples of box models 83Table 3.6. Inclusion of ocean exchange in the Excel code for the box model ofsalinity of a coastal basin resulting from river flow (compare Tables 3.1 and 3.2)Column Quantity Units Excel formula aA Time t days A2 ¼ A1 þ 1B R m 3 s 1 Entered by userC Average R m 3 s 1 C3 ¼ 0.5*(B3 þ B2)D Time step Dt days 1E R/V s 1 E3 ¼ C3*Tday/VolumeF days 5G Salinity S kg m 3 G1 ¼ 35; G2 ¼ G1 þ H2H DS kg m 3 H3 ¼ (I2 E3*G2)*D3I (35 S)/ kg m 3 per day I2 ¼ (35 G1)/F2a Based on the model S ¼ ((35 S)/ (R/V)*S))*t. Tday ¼ 86400, Volume ¼ 60 10 6 m 3 .Table 3.7. Inclusion of ocean exchange in the Matlab code for the box modelof salinity of a coastal basin resulting from river flow (compare Table 3.3)V ¼ 60e6; tau ¼ 5; dt ¼ 1;R_flood ¼ [ 0 1 5 10 15 20 15 10 5 0 0];S(1) ¼ 35;for n ¼ 2:30;if n < 12; R(n) ¼ R_flood(n); else; R(n) ¼ 0; end;R_average(n) ¼ 3600*24*(R(n) þ R(n 1))/2;dS ¼ S(n 1) * R_average(n) * dt/V;dS ¼ dS þ dt*(35 S(n 1))/tau;S(n) ¼ S(n 1) þ dS;end;Whether ocean exchange is important depends on the comparative values of 1/ andR/V and E/h. However, the latter two rates are often very seasonal, so there are usuallyseasons in which exchange is dominant. For density-driven exchange the exchangetime is dependent on the density difference between the basin and ocean and therefore,on the salinity difference.3.3.4 Surface heatingWe use the same box modelas employed for salt in Sections 3.3.1 to 3.3.3, but in thissection consider heat. The box is again well mixed and has a temperature T. To convertthe concentration of heat energy (J m 3 ) to temperature we must divide by specific