# RE: [ferret_users] Re: volume of watermass

```Hi Jaci Brown,
```
But the thickness (not the z in the data) of the density layer (27.6 to 27.7) will vary with place and time.
```
Praveen

Quoting Jaci.Brown@xxxxxxxx:

```
```I think it is better to first integrate then use zaxreplace.
Something like:

Temp_int=temp[z=@iin]
temp_iso = ZAXREPLACE(temp_int,sigma,z[gz=isoz])*0+1 ! to make
everything to 1
Let vol=temp_iso[z=27.7]-temp_iso[z=27.6]

Jaci Brown

-----Original Message-----
From: owner-ferret_users@xxxxxxxx [mailto:owner-ferret_users@xxxxxxxx]
On Behalf Of Praveen V K
Sent: Monday, 18 August 2008 11:21 AM
To: ferret_users@xxxxxxxx
Subject: [ferret_users] Re: volume of watermass

Hi all,

let me know whether I am doing right or not.

I changed my tracer (temp) data into sigma levels using ZAXREPLACE

define axis/z=19:29:0.1 isoz
temp_iso = ZAXREPLACE(temp,sigma,z[gz=isoz])*0+1 ! to make everything to
1

Now to find volume of a watermass in a specified sigma level
(27.6-27.7), I did following

Let  vol = temp_iso[x=@din,y=@din,z=27.6:27.7@din]

note: I have the proper masking

Am I doing the right?

Thanks

Praveen

```
```Hi all,
I have a 3D density data, derived from my model tracers.
Can ferret calculate the volume of watermass between a specified
isopycnal range?
```
```
```
```Any suggestions will be a great help.
```
```
```
```Praveen
```
```

```
```

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Praveen V K
Earth and Atmospheric Sciences
University of Alberta