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

[Dennis Shea]

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
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at mailman.ucar.edu
>>> List instructions, subscriber options, unsubscribe:
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>>>
>>
>
> --
> S.Rahimi
>
>
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