[ferret_users] computing Mixed-layer temperature

[Igaratza Fraile-Ugalde <igaratza@xxxxxxxxxxxxxxxxxxxx>]

Dear all,

I have a netCDF file with the output of a ocean circulation model and 
I'm trying to calculate the mixed-layer temperature.
I have all the necessary data in three files: mixed layer depth, 
temperature at constant different levels (25 in my case) and the depth 
of each layer (only for temperature). This is how it looks:
yes? sh da
    currently SET data sets:
   1> ./run021_monm.ocn.620-719.HMXL.nc (default)
name     title                                                         
   I         J         K         L
 HMXL     Mixed-Layer Depth                        1:100     1:116     
...       1:1200

   2> ./run021_monm.ocn.620-719.TEMP.nc
name     title                                                          
  I         J         K         L
 TEMP     Potential Temperature                    1:100     1:116     
1:25      1:1200

   3> ./depth_ZT.nc 
name     title                                                       
     I         J         K         L
ZT       depth from surface to midpoint of layer      ...       
...       1:25      ...

What I want to do is to calculate the average temperature between the 
surface (k=1) and the mixed layer depth (hmxl)(k=?). Since the mixed 
layer depth is probably between two levels (k) I  have to interpolate 
somehow. Does anyone have an idea how to do it?
I tried with simple statements like
yes? let  temp_hmxl=temp[d=2,k=1:hmxl@ave,l=1]

but it gives a syntax error. So basically I have two problems: First how 
to specify to average between 1 and a variable number (hmxl). And the 
second, how to interpolate between the two layers.


Thanks for your help!

Cheers,
Igaratza