[ncl-talk] NDVI from Advanced Very High-Resolution Radiometer (AVHRR)

[Setareh Rahimi]

Dear Dennis,
I profoundly appreciate your kind attention and the time you considered
downloading the files and checking them. Now I found out what is the
problem. so many many thanks!
Best wishes,



On Tue, Jun 21, 2022 at 10:09 PM Dennis Shea <shea at ucar.edu> wrote:

> I downloaded 5 files for a test.
>
> %> ncl NDVI_anomaly.ncl
>
> Copyright (C) 1995-2017 - All Rights Reserved
>  University Corporation for Atmospheric Research
>  NCAR Command Language Version 6.5.0
>  The use of this software is governed by a License Agreement.
>  See http://www.ncl.ucar.edu/ for more details.
>
>
> Variable: fils
> Type: string
> Total Size: 40 bytes
>             5 values
> Number of Dimensions: 1
> Dimensions and sizes:   [5]
> Coordinates:
> (0)     AVHRR-Land_v005_AVH13C1_NOAA-09_19860101_c20170612092103.nc
> (1)     AVHRR-Land_v005_AVH13C1_NOAA-09_19860102_c20170612093403.nc
> (2)     AVHRR-Land_v005_AVH13C1_NOAA-09_19861229_c20170612212717.nc
> (3)     AVHRR-Land_v005_AVH13C1_NOAA-09_19861230_c20170612214313.nc
> (4)     AVHRR-Land_v005_AVH13C1_NOAA-09_19861231_c20170612215936.nc
>
> Variable: prc
> Type: float
> Total Size: 518400000 bytes
>             129600000 values
> Number of Dimensions: 3
> Dimensions and sizes:   [time | 5] x [latitude | 3600] x [longitude | 7200]
> Coordinates:
>             time: [1826..2190]
>             latitude: [89.975..-89.97499]
>             longitude: [-179.975..179.975]
> Number Of Attributes: 7
>   long_name :   NOAA Climate Data Record of Normalized Difference
> Vegetation Index
>   units :       1
>   grid_mapping :        crs
>   standard_name :       normalized_difference_vegetation_index
>   _FillValue_original : -9999
>   _FillValue :  -9999
> ========================================================================
> ========================================================================
> ========================================================================
> It seems to me that you have path or file problems.
> I am not sure what else I can do.
>
> Others?
>
>
>
> On Tue, Jun 21, 2022 at 5:49 AM Setareh Rahimi <setareh.rahimi at gmail.com>
> wrote:
>
>> Dear Dennis,
>> So many thanks for your advice. I run the script on a remote server with
>> at least *1 terabyte* of memory. I think this is not the case.
>> I used the below commands to check the files:
>> ===========================================
>> fils = systemfunc("ls [1-2][8-9-0-1]*/*nc")
>>    print(fils)
>>
>>    f   = addfiles (fils, "r")
>>
>>    x   = short2flt(f[:]->NDVI)
>>
>>    printVarSummary(x)
>> ===========================================
>> , and attached the result. Please look at the image, and kindly help me
>> sort the issue out. I do not know what is wrong with the files I downloaded.
>> best regards,
>>
>> On Sat, Jun 18, 2022 at 10:52 PM Dennis Shea <shea at ucar.edu> wrote:
>>
>>> Based on the provided information, I have no idea why you would get
>>> "returned nothing to me"
>>>
>>> I know that NDVI files are 0.1 degree resolution (3600,7200). You have
>>> 36 years (1986-2021) of daily data.
>>> So, 36*365=13140   [+ a few Leap Year days)
>>>
>>>    prc(13140,3600,7200)    => daily data
>>>
>>> A lot of memory is needed. Maybe your computer can not handle this?
>>>
>>> After the
>>>       xM = calculate_monthly_values (prc, "avg", 0,opt)
>>>       printVarSummary(xM)
>>>
>>>    xM(432,3600,7200)
>>>
>>>
>>>
>>> On Sat, Jun 18, 2022 at 5:01 AM Setareh Rahimi via ncl-talk <
>>> ncl-talk at mailman.ucar.edu> wrote:
>>>
>>>> Dear all,
>>>>
>>>> I need to calculate the monthly anomaly of the Normalized Difference
>>>> Vegetation Index (NDVI), from Advanced Very High-Resolution Radiometer
>>>> (AVHRR) sensor. I have downloaded AVHRR data (1986-2021) from the link
>>>> below:
>>>>
>>>> https://www.ncei.noaa.gov/metadata/geoportal/rest/metadata/item/gov.noaa.ncdc:C01558/html
>>>> I first tried to prepare a script to combine all the data, and then
>>>> calculate the monthly average from daily data ( the link provides daily
>>>> data). After having monthly data I tried to figure out anomalies (the
>>>> script has been attached). But NCL stopped and returned nothing to me. I
>>>> just wonder what is wrong. Please kindly advise me on this issue.
>>>> Best wishes,
>>>>
>>>>
>>>> --
>>>> S.Rahimi
>>>>
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>>>
>>
>> --
>> S.Rahimi
>>
>>

-- 
S.Rahimi
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