Hi -
Thank you for the report. The units of the integral should be in
meters. According to the General information about transforms
When calculating integrals and derivatives (@IIN,
@DIN, @DDC, @DDF, and @DDB) Ferret attempts to use standardized
units for the grid coordinates. If the underlying axis is in a
known unit of length Ferret converts grid box lengths to
meters.
So, assuming your grid is in units of Longitude/Latitude, and Meters
for depth, then the result would be in meters. The only code change
between v6.1 and v6.64, is the result of this discussion about the
latitude correction for computations on the globe,
../fu_2009/msg00506.html
which applied in particular to irregularly-spaced grids and grids
where the coordinate values are not centered in their grid boxes.
The difference for that calculation for fairly small regions such as
yours and small grid boxes, should not be significant.
The other thing that occurred before v6.64 is a change in the
compilers we use to build Ferret. I do see a difference in Ferret
executables built with the previous compiler and the current one,
when I try computing a computation over var[X=@DIN,Z=@DIN] as you
are doing. We'll look into this more.
Ansley
On 11/21/2010 8:47 PM, Chaojiao.Sun@xxxxxxxx wrote:
Hi,
We recently upgraded our old FERRET v6.1 to the new v6.64 on a Dell M905 blade server running Suse Linux Enterprise Server 11, with the executables "64-bit Linux v6.6.4 Linked with NetCDF-4 libraries" downloaded from the FERRET website.
There was an unexpected change to the volume transport calculation: I used to get m^3 in my transport calculation, and by dividing by 10^6, I would get transport in Sv. Now when I run the same program, the unit seems to be no longer in m^3. What has changed?
Here is an example:
Vortex> ferret
NOAA/PMEL TMAP
FERRET v6.64
Linux(gfortran) 2.6.9-89.0.20.ELsmp - 09/16/10
22-Nov-10 12:28
yes? use uvw.relax.05.clim.2065-2085.nc
yes? show data
currently SET data sets:
1> ./uvw.relax.05.clim.2065-2085.nc (default)
name title I J K L
U zonal current 1:1191 1:968 1:47 1:1
V meridional current 1:1191 1:968 1:47 1:1
WT vertical velocity T-points 1:1191 1:968 1:47 1:1
AVERAGE_T1
Start time for average period ... ... ... 1:1
AVERAGE_T2
End time for average period ... ... ... 1:1
AVERAGE_DT
Length of average period ... ... ... 1:1
yes? list v[x=113.5:116@din,y=-32,z=0:200@din]
VARIABLE : meridional current (m/sec)
DATA SET : OFAM Mk3.5 A1B Relax
FILENAME : uvw.relax.05.clim.2065-2085.nc
LONGITUDE: 113.5E to 116E (XZ integ.)
LATITUDE : 32S
DEPTH (m): 0 to 200 (XZ integ.)
TIME : 01-MAY-2065 12:00 NOLEAP
-2616.
Question: what is the unit of this transport value of -196.3?
Please note: by manual calculation, I should get about -4 Sv.
Regards,
Chaojiao
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