# [ncl-talk] Pressure-height plot for different seasons

Mary Haley haley at ucar.edu
Fri Mar 11 15:59:34 MST 2016

```You need to be able to extract day 1 of  months 3, 6, 9, and 12 from your
time array so that you can locate where to put the MAM, JJA, SON, and DJF
labels.

​If your time array is one that is in a "standard" format like "days since
2004-1-1" or "months since 2004", then you can use cd_calendar to extract
the years, months, days, etc:

;---Reverse engineer the time array to get back year, month, day, etc
dates  = cd_calendar(time,0)    ; n x 6 array                         years
= toint(dates(:,0))
months = toint(dates(:,1))
days   = toint(dates(:,2))

You can then use this information to get the desired indexes from your time
array:

;---Start constructing the strings for the X axis labels
month_vals  = (/  3,    6,    9,    12/)     ; months where we want
labels
season_strs = (/"MAM","JJA","SON","DJF"/) + "-"

;---Get the indexes for the first day of the month for the first month of
each season
ii  =
ind(months.eq.3.or.months.eq.6.or.months.eq.9.or.months.eq.12.and.days.eq.1)
nii = dimsizes(ii)

xaxis_labels = new(nii,string)
do n=0,dimsizes(month_vals)-1
xaxis_labels =
where(months(ii).eq.month_vals(n),season_strs(n)+years(ii),xaxis_labels)
end do
​
See the attached script, which uses a dummy array to create an XY plot with
the time labels on the X axis.

--Mary

On Mon, Mar 7, 2016 at 12:41 PM, sudipta sarkar <sdptsarkar2 at gmail.com>
wrote:

> Hi Folks
> I want to plot a pressure-height plot against seasonal values
> (DJF,MAM,JJA,SON) for different years. My variable has dimensions for
> season, time and level.
>
> I can collapse the merge the season and time dimensions to show have a 2D
> array of time and level but I am not sure how to get a pressure-time plot
> from this where the x-axis will be labeled in terms of seasons from
> different years like: DJF-2004,MAM-04,JJA-2004,SON-2004,DJF-2005 like this.
>
> Any suggestion how I can get this done?
>
> Regards
>
>
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