Changeset 2165
- Timestamp:
- 2010-10-06T14:18:48+02:00 (14 years ago)
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- 1 edited
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branches/DEV_R1821_Rivers/DOC/TexFiles/Chapters/Chap_SBC.tex
r1320 r2165 36 36 term to observed SST and/or SSS (\np{ln\_ssr}=true); the modification of fluxes 37 37 below ice-covered areas (using observed ice-cover or a sea-ice model) 38 (\np{nn\_ice}=0,1, 2 or 3); the addition of river runoffs as surface freshwater39 fluxes (\np{ln\_rnf}=true);the addition of a freshwater flux adjustment in38 (\np{nn\_ice}=0,1, 2 or 3); the addition of river runoffs (\np{ln\_rnf}=true); 39 the addition of a freshwater flux adjustment in 40 40 order to avoid a mean sea-level drift (\np{nn\_fwb}= 0, 1 or 2); and the 41 41 transformation of the solar radiation (if provided as daily mean) into a diurnal … … 574 574 575 575 It is convenient to introduce the river runoff in the model as a surface 576 fresh water flux. 577 576 fresh water flux. This is the defualt option within NEMO, and there is then 577 the option for the user to increase vertical mixing in the vicinity of the rivermouth. 578 578 579 579 %Griffies: River runoff generally enters the ocean at a nonzero depth rather than through the surface. Many global models, however, have traditionally inserted river runoff to the top model cell. Such can become problematic numerically and physically when the top grid cells are reÞned to levels common in coastal modelling. Hence, more applications are now considering the input of runoff throughout a nonzero depth. Likewise, sea ice can melt at depth, thus necessitating a mass transport to occur within the ocean between the liquid and solid water masses. … … 587 587 %ENDIF 588 588 589 However, this method is not very appropriate for coastal modelling. As such its now possible 590 to specify, in a netcdf input file, the temperature and salinity of the river, along with the 591 depth (in metres) which the river should be added to. This enables to river to be correctly 592 added through the water column, instead of as a surface flux, and also means the temperature 593 or salinity (for low salinity outflow) of the river impacts the surrounding ocean. 594 595 For temperature -999 is taken as missing data and the river temperature is taken to be the 596 surface temperatue at the river point. For the depth parameter a value of -1 means the 597 river is added to the surface box only, and a value of -999 means the river is added through 598 the entire water column. 599 600 Namelist options, ln_rnf_depth, ln_rnf_sal and ln_rnf_temp control whether the river attributes 601 (depth, salinity and temperature) are read in and used. If these are set as false the river is 602 added to the surface box only, assumed to be fresh (0psu), and/or taken as surface temperature 603 respectively. 604 605 It is also possible for runnoff to be specified as a negative value for modelling flow through 606 straits, ie, modelling the baltic flow in and out of the north sea. When the flow is out of the 607 domain there is no change in temperature and salinity, regardless of the namelist options used. 608 609 The runoff value and attributes are read in in sbcrnf. The mass/volume addition is added to the 610 divergence term in sbc_rnf_div. The dilution effect of the river is automatically applied through 611 the vertical tracer advection, and the direct flux of tracers into the domain is done in trasbc. 589 612 590 613
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