[ncl-talk] Onset dates

[ousmane ndiaye]

Dear all,
I am happy to share my onset program and if someone can improve it.
It takes a 1D matrix and look for the first occurrence of an "onset date"
which is define as : "*first time less than 3 consecutive days record more
or equal than 20mm and not followed just afterward by a period of 10
consecutive dry days, a rainy days is here define as 1mm*"
all these values are parameters than can be changed. It was for an
agricultural planting date purpose working with daily rainfall.
Ousmane


On Fri, Nov 23, 2018 at 5:03 PM Soma Roy <somaroy892 at gmail.com> wrote:

> Thank you very much for sharing these information.
>
> Cheers!
> Soma
>
> On Fri, Nov 23, 2018, 21:24 Dennis Shea <shea at ucar.edu wrote:
>
>> As noted, there is no NCL software that calculates (Indian) monsoon onset
>> and withdrawal.
>>
>> Much has been written on this topic.
>> Please see the following. Perhaps, you could use the information to write
>> your own.
>>
>> *Hydrological Definition of Indian Monsoon Onset and Withdrawal*
>> <https://doi.org/10.1175/1520-0442(2003)016%3C3200a:AHDOIM%3E2.0.CO;2>
>> J. Fasullo and P. J. Webster
>> J. Climate: 2002
>>
>>
>> *Objective Determination of the Date of Onset of Monsoon  Rainfall over
>> India based on Duration of Persistence
>> <http://www.cmmacs.ernet.in/cmmacs/Publications/resch_rep/rrcm0711.pdf>*P.
>> Goswami and K.C. Gouda
>> Research Report RR CM 0711
>> June 2007
>>
>> *Objective determination of monsoon season onset, withdrawal, and length*
>> <https://doi.org/10.1029/2009JD012795>
>> B.I. Cook, B.M.Buckley
>> Climate and Dynamics (2009)
>>
>> *Determination of Onset an d Withdrawal Dates of Summer Monsoon  across
>> India using NCEP/NCAR Re-analysis*
>> <https://www.tropmet.res.in/~lip/Publication/RR-pdf/RR-124.pdf>
>> N. Singh, A.A. Ranade
>> 2010
>>
>>
>> *Characterizing the onset and demise of the Indian summer monsoon
>> <https://doi.org/10.1002/2016GL068409>*R. Noska, V. Misra
>> 20 April 2016
>>
>>
>> *Onset and withdrawal of the large-scale South Asian monsoon:     *
>> <https://doi.org/10.1002/2016GL071026>
>> * A dynamical definition using change point detection: MONSOON ONSET*
>> <https://doi.org/10.1002/2016GL071026>
>> J.M. Walker, S. Bordoni
>> Geophysical Research Letters 43(22) ·
>> November 2016
>>
>> On Fri, Nov 23, 2018 at 6:02 AM Appo derbetini <appopson4 at gmail.com>
>> wrote:
>>
>>> Hello Soma,
>>> I don't think that there is a tool available in NCL which can be used
>>> for what you are requesting.
>>> Here a link to a good paper where Onset and Retreat of rainy seasons are
>>> computed
>>>
>>> https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016JD025428
>>>
>>>
>>> Cheers
>>>
>>> Le jeu. 22 nov. 2018 à 21:46, Soma Roy <somaroy892 at gmail.com> a écrit :
>>>
>>>> Hello,
>>>> Is there any technique available in ncl to calculate *onset* and
>>>> *withdrawal* dates as *Julian* *days* (in spatial domain) for
>>>> individual years?
>>>>
>>>> I am using daily gridded dataset over Indian region.
>>>>
>>>> Please kindly inform me the above.
>>>>
>>>> Thanking you,
>>>> Soma
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