Re: [ferret_users] difference in trend computation from CDO and from ferret

To: Pratik Kad <pratikkad17@xxxxxxxxx>, ferret users <ferret_users@xxxxxxxx>
Subject: Re: [ferret_users] difference in trend computation from CDO and from ferret
From: saurabh rathore <rohitsrb2020@xxxxxxxxx>
Date: Wed, 19 Jun 2019 15:35:44 +1000
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Hi Pratik,

Thank for your reply. I checked the calendar and time steps of my data that is why I am multiplying my slope with 12 to convert it into per year. But the pattern of the slope is wrong, look the pattern of the slope that I plotted from the trend calculation of cdo with the same data, it is not matching with the pattern of the slope computed using ferret. I checked it with NCL also and its pattern is same as cdo but not like ferret.

One thing I can guess that ferret is doing something else with the time index but I am not able to understand it.

Cheers, Saurabh

On Wed, Jun 19, 2019 at 3:34 PM saurabh rathore <rohitsrb2020@xxxxxxxxx> wrote:

Hi Pratik,

Thank for your reply. I checked the calendar and time steps of my data that is why I am multiplying my slope with 12 to convert it into per year. But the pattern of the slope is wrong, look the pattern of the slope that I plotted from the trend calculation of cdo with the same data, it is not matching with the pattern of the slope computed using ferret. I checked it with NCL also and its pattern is same as cdo but not like ferret.

One thing I can guess that ferret is doing something else with the time index but I am not able to understand it.

Cheers, Saurabh

On Wed, Jun 19, 2019 at 2:32 PM Pratik Kad <pratikkad17@xxxxxxxxx> wrote:

Regards
Pratik

On Wed, Jun 19, 2019 at 12:09 PM saurabh rathore <rohitsrb2020@xxxxxxxxx> wrote:

Dear Ferreters,
G'day

I am having very strange problem in computation of trend (slope). I am replotting my data after 1 year or so and I want to compute trend from it. I am having my data from 2005-2015.

Here is the attached data.

from ferret I used this script
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
use ohc-ferret.nc
let p=t[gt=ohcg1]
let q=ohcg1
go regresst
fill/lev=(-inf)(-20,20,4)(inf)/pal=blue_orange slope*10^-7*12
frame/file=test-ferret.png
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

REGARDS

Saurabh Rathore

Research Scholar (PhD.)

Centre For Oceans, Rivers, Atmosphere & Land Science Technology

Indian Institute Of Technology, Kharagpur

contact :- 91- 8345984434