[ncl-talk] detrend not working right and calculate_monthly_values

Ipshita Majhi ipmajhi at alaska.edu
Tue Feb 16 14:49:59 MST 2016


Sorry about the confusion and wrong use of words. I will be more carefully
about framing my words. Thank you so much for your guidance.

Best Regards
Ipshita

On Tue, Feb 16, 2016 at 12:47 PM, Dennis Shea <shea at ucar.edu> wrote:

> TYour comments do not make any sense to me. Actually, they are rather
> frustrating.
>
> [1] The CDO  and NCL are not returning the correct results. They are two
> independent software tools. Something does not seem right here.
>
> [2] I am sure that neither were designed to work with 'weekly data'.
> 'Weekly data' can span across neighboring months.
> NCL's function requires that 'time' be recognized by 'cd_calendar'. Are
> the units of your variable  'weeks since ...'? Certainly NCL and, likely,
> the CDO are not going to partition a week that spans two months.
>
> [3] You make statements like "detrend not working right and
> calculate_monthly_values". You give no particulars.
> Why do you say these are not working correctly?
>
>
>
> On Tue, Feb 16, 2016 at 1:14 PM, Ipshita Majhi <ipmajhi at alaska.edu> wrote:
>
>> Dear NCL,
>>
>> I have been working on making a plot with correlation between detrended
>> data (snow cover extent) and I had first
>> used CDO to convert weekly data to monthly data. In the process the lat
>> and lon cordinates became y and x.
>> It works fine if till I reorder it. But it is not calculating dtrend
>> correctly, all the values are fill values.
>>
>> I worked on using calculate_monthly_values to see if I could use it
>> convert weekly to monthly in NCL and I could not use it. I would be
>> grateful for any input
>>
>> Here is the code I am using
>>
>> ;============================================
>> ; set up parameters
>> ;============================================
>>
>> ;This is extracting latitude of Western Europe
>> ;Reading in the data
>> a=addfile("~/Documents/NCL_files/Snow_cover_IMS/NCL_codes/sce_mon_mean.nc","r")
>> ; open output netCDF file
>> b=addfile("~/Documents/NCL_files/Snow_cover_IMS/
>> nhsce_v01r01_19661004_20140602.nc","r")
>>
>> ;Extracting  snow cover extent (sce) from respective data files
>>
>> sce=byte2flt(a->sce)
>>
>> sce at _FillValue = 9.9621e+36
>>
>> lat=b->latitude
>> lon=b->longitude
>>
>> sce at lat2d=lat
>> sce at lon2d=lon
>>
>> ;==============================================
>> ;Reading in JJAS rainfall
>>
>> JJAS_1871_2012
>> =asciiread("~/Documents/NCL_files/SST/Monthly/jjas_1871_2012.txt",(/142,1/),"float")
>>
>> ;Extracting JJAS for 1967 to 2012
>>
>> JJAS_1967_2012=JJAS_1871_2012(96:141,0)
>>
>> ;============================================
>> ;Extracting monthly data for sce
>>
>> Jan_sce = new((/46,88,88/),float)
>>
>> Jan_sce at _FillValue = 9.9621e+36
>>
>> Jan_sce at lat2d=lat
>> Jan_sce at lon2d=lon
>>
>> ;==========================================
>>
>> do nyr=0,551,12
>>
>> Jan_sce(nyr/12,:,:) =sce(nyr,:,:)
>>
>> end do
>>
>> Jan_reorder=Jan_sce(y|:,x|:,time|:)
>>
>> Jan_dt=dtrend(Jan_reorder,False)
>>
>>
>> Jan_reorder at _FillValue = 9.9621e+36
>>
>> corr_jan=escorc(Jan_dt,JJAS_1967_2012)
>>
>>
>>
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>>
>


-- 
Ipshita Majhi
PhD Candidate
University of Alaska , Fairbanks
Atmospheric Science Department
(907)978-4220 ipmajhi at alaska.edu
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