[ncl-talk] dim_variance_n_Wrap

[Dennis Shea]

 f  = addfile("all_BoB.nc", "r")
 prc =f->pre(:,{65:110},{0:30})

 prc_reorder = prc(time|:,latitude|:,longitude|:)
;printVarSummary(prc_reorder)
;printMinMax(prc_reorder,0)

 prcTrace = 1.0   ; mm
 prcRain   = *where*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml>(prc_reorder.ge.prcTrace,
prc_reorder,  prc_reorder at _FillValue)
 *copy_VarMeta*
<https://www.ncl.ucar.edu/Document/Functions/Contributed/copy_VarMeta.shtml>(prc_reorder,
prcRain)
;printVarSummary(prcRain)
;printMinMax(prcRain,0)

 prcDayRainAvg = *dim_avg_n_Wrap*
<https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_avg_n_Wrap.shtml>(prcRain,
0)
 prcDayRainAvg at long_name = "Rain Total on Rain Days: prcTrace="+prcTrace
 prcDayRainVar  = *dim_variance_n_Wrap*
<https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_variance_n_Wrap.shtml>
(prcRain,0)
 rcDayRainVar at long_name = "Rain Varianceon Rain Days: prcTrace="+prcTrace

;printVarSummary(prcDayRainAvg)
;printMinMax(prcDayRainAvg,0)

;printVarSummary(prcDayRainVar)
;printMinMax(prcDayRainVar,0)

You will still get large variance numbers. Rain amounts span prcTrace to
(say) 500.



On Fri, Jan 18, 2019 at 11:38 PM Md. Jalal Uddin <dmjalal90 at gmail.com>
wrote:

> Thanks for your kind explanation. Could I calculate and plot of per day
> variance, also for greater than 0 rainfall?
>
> On Thu, Jan 17, 2019 at 1:58 PM Dennis Shea <shea at ucar.edu> wrote:
>
>> More:
>> *dim_variance_n_Wrap*(prc_reorder,*0*)   ; variance over *all days*:  *DRY
>> and WET* seasons
>>
>> Consider Pune, India.
>>    (say; made up numbers) day 170:   mean over DRY and WET seasons 10mm;
>> range 0-500mm
>>
>>
>> On Thu, Jan 17, 2019 at 2:12 PM Dennis Shea <shea at ucar.edu> wrote:
>>
>>> Well, you live with the monsoon.
>>>
>>> Some days have zero precipitation and some monsoon days have VERY LARGE
>>> daily amounts.
>>> Hence large variance.
>>>
>>> On Wed, Jan 16, 2019 at 10:53 PM Md. Jalal Uddin <dmjalal90 at gmail.com>
>>> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I am getting a too large variation of rainfall. I used
>>>> dim_variance_n_Wrap function to calculate variance. The first figure is for
>>>> the mean rainfall and the second one is for variance at the same time.
>>>>
>>>> Could anyone help me to understand where I am wrong?
>>>>
>>>> Variable: prc_reorder
>>>> Type: double
>>>> Total Size: 491961600 bytes
>>>>             61495200 values
>>>> Number of Dimensions: 3
>>>> Dimensions and sizes: [time | 2847] x [latitude | 120] x [longitude |
>>>> 180]
>>>> Coordinates:
>>>>             time: [ 120..6939]
>>>>             latitude: [0.125..29.875]
>>>>             longitude: [65.125..109.875]
>>>> Number Of Attributes: 4
>>>>   missing_value : -nan
>>>>   _FillValue : -nan
>>>>   units : mm
>>>>   long_name : precipitation
>>>>
>>>> Best regards,
>>>> Jalal
>>>> --
>>>> *Md. Jalal Uddin*
>>>> MSc in Applied Meteorology (English Language)
>>>> Nanjing University of Information, Science and Technology, China
>>>> B.Sc. in Disaster Management (Hons.)
>>>> Patuakhali Science and Technology University, Bangladesh.
>>>> Cell: +8613260859092, +8801792052662
>>>> Web: www.dmjalal90.weebly.com
>>>> Facebook: jalal.hossen.39
>>>> LinkedIn: https://bd.linkedin.com/in/md-jalal-uddin-80a026b0
>>>> Twitter: dmjalal90
>>>> Skype: dmjalal90
>>>> _______________________________________________
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>>>
>
> --
> *Md. Jalal Uddin*
> MSc in Applied Meteorology (English Language)
> Nanjing University of Information, Science and Technology, China
> B.Sc. in Disaster Management (Hons.)
> Patuakhali Science and Technology University, Bangladesh.
> Cell: +8613260859092, +8801792052662
> Web: www.dmjalal90.weebly.com
> Facebook: jalal.hossen.39
> LinkedIn: https://bd.linkedin.com/in/md-jalal-uddin-80a026b0
> Twitter: dmjalal90
> Skype: dmjalal90
>
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