[ncl-talk] SPI calculation

[Mary Haley]

Soma,

The spi_2.ncl script shows you how to calculate the yyyymm variable:

  year    = yyyymm/100
  yrStrt  = year(0)
  yrLast  = year(ntim-1)
  nyear   = yrLast-yrStrt+1
  yyyymm  = yyyymm_time(yrStrt, yrLast, "integer")

You don't need the "date" or "yyyymm" arrays, because you already have the
year information. Use ispan to generate the "year" array and now you can
get your yyyymm and yrfac values as needed:

  year    = ispan(1970,2010,1)
  ntim    = dimsizes(year)
  yrStrt  = year(0)
  yrLast  = year(ntim-1)
  nyear   = yrLast-yrStrt+1
  yyyymm  = yyyymm_time(yrStrt, yrLast, "integer")
  yrfrac  = (/ yyyymm_to_yyyyfrac(yyyymm, 0.0) /)

--Mary








On Wed, Nov 28, 2018 at 1:05 PM Soma Roy <somaroy892 at gmail.com> wrote:

> Thank you very much for the hint.
> I will check it.
>
> But mannualy we can't set the "date" range in the script without using CDO?
>
> Please kindly inform me.
>
> Thanking you,
> Soma
>
>
> On Thu, Nov 29, 2018, 01:28 Guilherme Martins <jgmsantos at gmail.com wrote:
>
>> I don't know if you use climate data operators or cdo software.
>>
>> You can set the data in your file.
>>
>> Exemple
>>
>> cdo settaxis,1970-01-01,00:00:00,1mon input.nc output.nc
>>
>> Guilherme.
>>
>>
>> Em qua, 28 de nov de 2018 16:35, Soma Roy <somaroy892 at gmail.com escreveu:
>>
>>> Hello,
>>>
>>> I am trying to calculate standadize precipitation index using monthly
>>> gridded dataset.
>>>
>>> Dimension of data is like below;
>>> Rainfall(12x41) (months x years).
>>>
>>> I am using the script from the below link;
>>> https://www.ncl.ucar.edu/Applications/Scripts/spi_2.ncl
>>>
>>> But in my dataset there is no variable as "date".
>>>
>>> Can we manually set the date range inside the script?
>>>
>>> I am using rainfall dataset for 1970-2010.
>>>
>>> Please kindly inform me how we can modify it over the same script.
>>>
>>> Thanking you,
>>> Soma
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