Thanks a lot for your suggestion and it is giving single scalar value now. Actually I was setting z=1 before applying the previously stated mask commands for calculating area. I guess he was using "." sign like Area=mask[x=@din.y@din] for multiplication of latitude and longitude grids instead of using comma which might be the possible reason of multiple areas coming for each latitude. Best, Dogar
Date: Wed, 30 Oct 2013 09:14:18 +1100 From: russell.fiedler@xxxxxxxx To: ferret_users@xxxxxxxx Subject: Re: [ferret_users] How to divide a variable by area used in calculation
Hi,
A couple of issues here.
First, it looks like there was a typo resulting in an incorrect
index for the mask in the reply. It should be the K index being
set to 1 (i.e. the surface) not L (time).
so
let mask = if heat_anm_ctr1[K=1] then 1
let surface_area = mask[x=@din,y=@din]
let heat_flux = ohc/surface_area
Alternatively you could do the vertical integral first and then
just average over the area
let heat_intz = heat[z=@din]*3990
let heat_flux = heat_intz[x=@ave,y=@ave]
Second, I think that you were getting multiple areas for each
depth, not latitude due to the incorrct index unless you were
overriding the region in your list command.
Russ
On 29/10/13 18:59, Star Physicist wrote:
Hi,
In stead of giving single scalar value this _expression_ gives me
multiple areas for each latitude. 2ndly I doubts that integral
for x and y counts grids along the boundaries twice. Any
suggestion?
Thanks,
Dogar
Date: Mon, 28 Oct 2013 09:03:01 0700
From: j_karmacharya@xxxxxxxxx
Subject: Re: [ferret_users] How to divide a variable by area
used in calculation
To: couragetoknowgc@xxxxxxxxxxx; ferret_users@xxxxxxxx
Hi Dogar,
If your vaiable has latlong information, I think this should
work:
Create a variable with unitary value from the desired variable
and use @din to compute area:
e.g.:
let mask=if heat_anm_ctr1[l=1] then 1
Jagadish
Dear Ferret users,
I am calculating Ocean Heat Content (OHC) as
follows and wanted to divide it by area used in
calculation. How can I do that:
set reg/x=180:180/y=60S:60N
!Defining rho x temp
let heat=rho[d=1] *temp[d=1]
!Integrating over the entire volume
let OHC=heat_anm_ctr1[x=@din,y=@din,z=@din]*3990
Now I want to divide this OHC by corresponding
area to get the unit as Joule/m^2. How to get
the area used in above calculation.
Thanks,
Dogar
Date: Mon, 28 Oct 2013 06:23:11 +0530
Subject: [ferret_users] netcdf point datasets
in ferret
From: ghanshamsangar@xxxxxxxxx
To: ferret_users@xxxxxxxx
Is it possible to open point datasets in
netcdf format following CF conventions (see
discrete sampling geometry in cf metedata
conventions1.6 document available online). I
could not find online documentation regarding
same. I am usinfg ferret 6.84. The dataset is
satellite derived wind vectors having relevant
fields (ucomp, vcomp, wind speed, Windows
direction, latitude, longitude, date/time of
each observation).
Ghansham
