Re: Question on the time coordinate of IPCC AR4 model output data?

I assume there was no calendar attribute for the time variable
since you manually added "gregorian". Not sure why you did this.
The default is "gregorian" or "standard".

Beginning with v5.1.0 [released 4 March 2009] NCL recognizes the
360, 365, and no leap calendars.

You could try time_at_calendar = "365_day" [same as "no_leap"]

I would be surprised if the appropriate calendar attribute
was not on the file.

leo.aries.g wrote:
> Hi, all
>
> I met some problems when dealing with monthly data of some IPCC
> AR4 model output.
> The problem is from the time coordinates, in general there are more
> than 1 value for some months
> in contrast to no values for some other months.
>
> For example , one output of psl (pressure at sea level) for GFDL in
> sresa1b scenario,
> with a filename "psl_A1.200101-220012.nc" , '
> downloaded from
> "ftp-esg.ucllnl.org/data5/sresb1/atm/mo/psl/gfdl_cm2_0/run1/psl_A1.200101-220012.nc"
>
> Here below is my scripts:
>
> path_name = "..."
> ymStrt = 200101
> ymLast = 209912
>
> fi = addfile(path_name + "psl_A1.200101-220012.nc"
> , "r")
> time = fi->time
> time_at_calendar = "gregorian"
> yyyymm = ut_calendar(time,-1)
> ntStrt = ind(yyyymm.eq.ymStrt)
> ntLast = ind(yyyymm.eq.ymLast)
> data = fi->"psl"
> time2 = yyyymm(ntStrt:ntLast)
>
> ntime = dimsizes(time2)
> time4 = new((/ntime/),integer)
> time4(0:ntime-2) = time2(1:ntime-1)
> time4(ntime-1) = 0
> nt = ind(time2.eq.time4)
> print(nt) ;
> here I got 4 output ( nt= 720, 732,744,756 ), corresponding to the cases
>
> with more than 1 values for some months
>
> yyyymmdd = ut_calendar(time,-2)
> print(time2(718:758) + " " + yyyymmdd(718:758)) ; to get more
> details, print the time coordinates in monthly and daily resolution
>
> ; Here below is the results
> (0) 206011 20601101
> (1) 206012 20601201
> *(2) 206101 20610101*
> *(3) 206101 20610131*
> (4) 206103 20610301
> (5) 206104 20610401
> (6) 206105 20610501
> (7) 206106 20610601
> (8) 206107 20610701
> (9) 206108 20610801
> (10) 206109 20610901
> (11) 206110 20611001
> (12) 206111 20611101
> (13) 206112 20611201
> *(14) 206201 20620101*
> *(15) 206201 20620131*
> (16) 206203 20620301
> (17) 206204 20620401
> (18) 206205 20620501
> (19) 206206 20620601
> (20) 206207 20620701
> (21) 206208 20620801
> (22) 206209 20620901
> (23) 206210 20621001
> (24) 206211 20621101
> (25) 206212 20621201
> *(26) 206301 20630101*
> *(27) 206301 20630131*
> (28) 206303 20630301
> (29) 206304 20630401
> (30) 206305 20630501
> (31) 206306 20630601
> (32) 206307 20630701
> (33) 206308 20630801
> (34) 206309 20630901
> (35) 206310 20631001
> (36) 206311 20631101
> (37) 206312 20631201
> *(38) 206401 20640101*
> *(39) 206401 20640131*
> /*(40) 206402 20640229*/
>
> ; remove the seasonal cycle
> x = rmMonAnnCycLLT(data({lat|-60.:-50.},lon|:,time|ntStrt:ntLast)) ;
> rmMonAnnCycLLT can not run because time dimension was not
>
> multiple of 12 (1 more value added between 20640101 to 20640229)
>
>
> Here is only one example, similar cases were often met when I deal
> with IPCC AR4 model output.
> What cause it and how should I deal with them? Does anyone know about
> these and can give me some advice?
>
> Thank!
>
>
> Lin
>
> Chinese Academy of Meteorological Sciences (CAMS),CMA
>
>
> 2009-07-07
> ------------------------------------------------------------------------
> leo.aries.g
> ------------------------------------------------------------------------
>
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Dennis J. Shea                  tel: 303-497-1361    |
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