Changeset 2165

Timestamp:

2010-10-06T14:18:48+02:00 (14 years ago)

Author:

rfurner

Message:

updated documentation to include new river options

File:

• branches/DEV_R1821_Rivers/DOC/TexFiles/Chapters/Chap_SBC.tex (modified) (3 diffs)

branches/DEV_R1821_Rivers/DOC/TexFiles/Chapters/Chap_SBC.tex

@@ -36 +36 @@
 term to observed SST and/or SSS (\np{ln\_ssr}=true); the modification of fluxes 
 below ice-covered areas (using observed ice-cover or a sea-ice model) 
-(\np{nn\_ice}=0,1, 2 or 3); the addition of river runoffs as surface freshwater 
-fluxes (\np{ln\_rnf}=true); the addition of a freshwater flux adjustment in 
+(\np{nn\_ice}=0,1, 2 or 3); the addition of river runoffs (\np{ln\_rnf}=true);
+ the addition of a freshwater flux adjustment in 
 order to avoid a mean sea-level drift (\np{nn\_fwb}= 0, 1 or 2); and the 
 transformation of the solar radiation (if provided as daily mean) into a diurnal 
@@ -574 +574 @@
 
 It is convenient to introduce the river runoff in the model as a surface 
-fresh water flux. 
-
+fresh water flux. This is the defualt option within NEMO, and there is then
+ the option for the user to increase vertical mixing in the vicinity of the rivermouth.
 
 %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
 
+However, this method is not very appropriate for coastal modelling.  As such its now possible
+ to specify, in a netcdf input file, the temperature and salinity of the river, along with the 
+depth (in metres) which the river should be added to.  This enables to river to be correctly 
+added through the water column, instead of as a surface flux, and also means the temperature 
+or salinity (for low salinity outflow) of the river impacts the surrounding ocean.
+
+For temperature -999 is taken as missing data and the river temperature is taken to be the 
+surface temperatue at the river point.  For the depth parameter a value of -1 means the 
+river is added to the surface box only, and a value of -999 means the river is added through 
+the entire water column.
+
+Namelist options, ln_rnf_depth, ln_rnf_sal and ln_rnf_temp control whether the river attributes 
+(depth, salinity and temperature) are read in and used.  If these are set as false the river is 
+added to the surface box only, assumed to be fresh (0psu), and/or taken as surface temperature 
+respectively.
+
+It is also possible for runnoff to be specified as a negative value for modelling flow through 
+straits, ie, modelling the baltic flow in and out of the north sea.  When the flow is out of the 
+domain there is no change in temperature and salinity, regardless of the namelist options used.
+
+The runoff value and attributes are read in in sbcrnf.  The mass/volume addition is added to the 
+divergence term in sbc_rnf_div.  The dilution effect of the river is automatically applied through 
+the vertical tracer advection, and the direct flux of tracers into the domain is done in trasbc.