[ncl-talk] trend of SST yearly and JJAS

[Izidine Pinto]

Hello Nitin,

1. I have plotted trend of sst/112 years (trend_yearly.ncl) and is working
fine, *In this I have to show only the trend which is 95% significant,
anyone knows?*

- You can use several statistical tests to test the significance of the
trend depending in your data. One of them is the Mann-Kendall
non-parametric trend test. See
https://www.ncl.ucar.edu/Document/Functions/Built-in/trend_manken.shtml for
the description. Calculate the p value and if it is less than 0.05 then the
trend is significant. You can plot the trend and then overlay with the p
values (see https://www.ncl.ucar.edu/Applications/Scripts/overlay_5.ncl
https://www.ncl.ucar.edu/Applications/Images/overlay_5_lg.png ).

2. I am trying to plot trend (trend_jjas.ncl) as per above but on seasonal
basis (JJAS) but it is showing some seasonal error, Kindly let me know *how
to compute seasonal trend JJAS (How to select JJAS per year?).*

 - Without knowing what exactly the seasonal error is make it difficult to
help.
Or what you can do is to create a new file containing only JJAS (you can
use cdo) and do the trend calculation using trend_yearly.ncl.

If you have any further questions please respond to the ncl-talk list.
Izidine



Izidine S. Pinto


On 7 September 2015 at 13:38, Nitin Patil <nitinpatil85 at gmail.com> wrote:

> Dear NCL user's,
>
> 1. I have plotted trend of sst/112 years (trend_yearly.ncl) and is working
> fine, *In this I have to show only the trend which is 95% significant,
> anyone knows?*
>
> 2. I am trying to plot trend (trend_jjas.ncl) as per above but on seasonal
> basis (JJAS) but it is showing some seasonal error, Kindly let me know *how
> to compute seasonal trend JJAS (How to select JJAS per year?).*
>
> *Note:* My data file looks like: SST monthly Jan 1901 to Dec 2012.
>
> --
> Regards,
> Nitin Patil
>
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