http://ferret.wrc.noaa.gov/Ferret/Documentation/Users_Guide/v52/fer_html.htm
--Ansley Manke Pacific Marine Environmental Laboratory Seattle
WA (206)526-6246
Mr Retish Senan wrote:
Hi Karen!The correct usage of the rho_un function is
rho_un(sal,temp,Z[G=temp]).So, the strange values you are getting is due to the fact that the
function is interpreting your temperature as salinity and vice versa..The confusion must have arised because the user's guide V4.91 has
given the wrong usage in an example on page 40. The correct usage is as
given in the list of functions on page 42.Regards
RetishOn Wed, 18 Oct 2000, Karen Bice wrote:
> I have a netcdf file that contains temperature and salinity on an XYZ
> grid. I am trying to use the rho_un function to calculate density.
>
> When I say
> let density = rho_un(temp, sal, Z[G=temp])
> I get density values that can't be right.
>
> For example, for a specific X,Y location, values look like this (the
> first column is depth in cm):
> TEMP SAL DENS
> 1250 / 1: 27.61 36.76 1019.
> 3750 / 2: 27.62 36.78 1029.
> 6250 / 3: 27.64 36.80 1039.
> 11250 / 4: 27.64 36.82 1057.
> 18750 / 5: 27.58 36.84 1081.
> 41250 / 6: 24.83 36.10 1139.
> 68750 / 7: 20.58 35.46 1192.
> 111250 / 8: 16.30 35.11 1261.
> 151250 / 9: 14.24 34.97 1323.
> 188750 / 10: 13.30 34.90 1384.
> 238750 / 11: 12.60 34.85 1481.
> 301250 / 12: 12.17 34.83 1648.
>
> But, more reasonable UNESCO values for in situ densities (in kg/m^3) for
> these T,S values would be:
> 1250 / 1: 1023.93
> 3750 / 2: 1024.04
> 6250 / 3: 1024.15
> 11250 / 4: 1024.38
> 18750 / 5: 1024.73
> 41250 / 6: 1025.99
> 68750 / 7: 1027.92
> 111250 / 8: 1030.60
> 151250 / 9: 1032.71
> 188750 / 10: 1034.48
> 238750 / 11: 1036.73
> 301250 / 12: 1039.44
>
> I know that rho_un expects Z in decibars (according to the user's
> guide), so I figured that it was using the actual depth values. But even
> if that were the case, those depths, interpreted as pressures in
> decibars shouldn't yield densities like those in my first list above.
>
> Is the output of rho_un actually something other than kg/m^3?
> Can anyone tell me what I am doing wrong here and how I can get good
> density values out of rho_un?
>
> Thanks very much.
>
> --
> Karen L. Bice, Assistant Scientist Mail Stop #23
> Dept. of Geology and Geophysics phone: (508) 289-3320
> Woods Hole Oceanographic Institution FAX: (508) 457-2187
> Woods Hole, MA USA 02543-1541
><>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>
RETISH SENAN
Research Student
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