Re: Integration over the vertical levels:

Hi Dennis,

Thank you for the explanation. I did individual averaging for some
coordinates and I think the averaging in ncl is just right as you suggested.
Thank you for the NCO link.
Regards,
Thejna.
 
----------------original message-----------------
From: "Dennis Shea" shea@ucar.edu
To: "Thejna Tharammal" ttharammal@marum.de
CC: "ncl-talk@ucar.edu" ncl-talk@ucar.edu
Date: Thu, 27 Dec 2012 09:16:27 -0700
-------------------------------------------------
 
 
> Hi Thejna
>
> Just looking at the numbers, I would say that the 'vavg=-296.803'
> looks about right. [The 52.5N, 13E is approximately for Berlin.]
>
> The 'dp' are layer thicknesses in pressure. They 'dp' look like they
> are in Pa. The look reasonable. The 'dp' are weights for
> each pressure level. The formula is:
>
> x_wgt_avg = SUM[ x(p)*wgt(p) ]/ SUM[ wgt(p) ]
>
> ---
> I am not sure how the 'ncwa' operator was used. Clearly, the -146
> is wrong if it is for the same location. Perhaps, you should
> send a help request to
>
> http://sourceforge.net/projects/nco/forums/forum/9830
>
> Note: ncl-talk does not respond to usage or help regarding the NCO.
>
> Good Luck
>
> On 12/27/12 7:25 AM, Thejna Tharammal wrote:
>> Thank you. I tried the steps and the results are as below:
>> ;=============================================================
>> Variable: dp
>> Type: float
>> Total Size: 479232 bytes
>> 119808 values
>> Number of Dimensions: 3
>> Dimensions and sizes: [26] x [48] x [96]
>> Coordinates:
>>
>>
>> Variable: vavg
>> Type: float
>> Total Size: 18432 bytes
>> 4608 values
>> Number of Dimensions: 2
>> Dimensions and sizes: [lat | 48] x [lon | 96]
>> Coordinates:
>> lat: [-87.15909455586285..87.15909455586285]
>> lon: [ 0..356.25]
>> Number Of Attributes: 3
>> units : Permil
>> long_name : Weighted Vertical Average: ~F33~d~F26~D in vapor
>> _FillValue : -9999
>> (0) vavg: min=-476.326 max=-260.598
>> (0) ---
>> (0) x=-269.741 dp=270.114 xdp=-72860.8
>> (1) x=-299.394 dp=498.721 xdp=-149314
>> (2) x=-349.433 dp=816.959 xdp=-285473
>> (3) x=-414.574 dp=1178.52 xdp=-488584
>> (4) x=-478.909 dp=1478.61 xdp=-708119
>> (5) x=-527.338 dp=1698.25 xdp=-895554
>> (6) x=-557.539 dp=1690.66 xdp=-942606
>> (7) x=-571.784 dp=1372.02 xdp=-784498
>> (8) x=-577.103 dp=1614.11 xdp=-931507
>> (9) x=-572.299 dp=1898.91 xdp=-1.08675e+06
>> (10) x=-538.315 dp=2233.97 xdp=-1.20258e+06
>> (11) x=-500.48 dp=2628.16 xdp=-1.31534e+06
>> (12) x=-484.412 dp=3091.88 xdp=-1.49775e+06
>> (13) x=-470.985 dp=3637.45 xdp=-1.71318e+06
>> (14) x=-432.153 dp=4279.27 xdp=-1.8493e+06
>> (15) x=-372.448 dp=5034.33 xdp=-1.87503e+06
>> (16) x=-325.192 dp=5922.63 xdp=-1.92599e+06
>> (17) x=-283.061 dp=6967.67 xdp=-1.97228e+06
>> (18) x=-251.629 dp=8197.11 xdp=-2.06263e+06
>> (19) x=-223.193 dp=9643.47 xdp=-2.15236e+06
>> (20) x=-193.715 dp=9425.81 xdp=-1.82592e+06
>> (21) x=-167.191 dp=8580.53 xdp=-1.43459e+06
>> (22) x=-143.797 dp=7158.41 xdp=-1.02936e+06
>> (23) x=-125.373 dp=5219.05 xdp=-654326
>> (24) x=-115.379 dp=2883.48 xdp=-332693
>> (25) x=-111.104 dp=1475.61 xdp=-163946
>> (0) ---
>> (0) LAT=52.5 LON=13 vavg=-296.803
>> (0) ---
>> ;=============================================================
>>
>> I am not sure how to interpret the dp values, could you please explain if
>> they are in the acceptable range?
>> For the same coordinates, I get lower (~ -146) using ncwa vertical
>> integration.
>> Thanks,
>> Thejna
>>
>> ----------------original message-----------------
>> From: "Dennis Shea" shea@ucar.edu
>> To: "Thejna Tharammal" ttharammal@marum.de
>> CC: ncl-talk@ucar.edu
>> Date: Wed, 26 Dec 2012 21:54:56 -0700
>> -------------------------------------------------
>>
>>
>>> Why not debug at one grid point?
>>>
>>>
>>>
>>> http://www.ncl.ucar.edu/Document/Functions/Built-in/dpres_hybrid
>>> _ccm
>>> .shtml
>>>
>>> Example 3 ... modified here
>>>
>>> ---
>>>
>>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>>>
>>> ....
>>>
>>> dp = dpres_hybrid_ccm (ps,p0,hyai,hybi) ; Pa
>>> xdp = x*dp ; (temporary variable)
>>> copy_VarCoords(x, xdp)
>>>
>>> vint = dim_sum_n( xdp, 1)
>>> dpsum= dim_sum_n( dp, 1)
>>> vavg = vint/dpsum ; weight average
>>>
>>> copy_VarCoords(ps, vavg) ; add variable meta data
>>> vavg@long_name = "Weighted Vertical Average: "+x@long_name
>>> vavg@units = x@units
>>> printVarSummary(vavg)
>>> print("vavg: min="+min(vavg)+" max="+max(vavg))
>>>
>>> LAT = 52.5 ; arbitrary grid point
>>> LON = 13.0
>>>
>>> nt = 0
>>> print("---")
>>> copy_VarCoords(x, dp)
>>> print("x="+x(nt,:,{LAT},{LON}) +" dp="+ dp(nt,:,{LAT},{LON}) +"
>>> xdp="+xdp(nt,:,{LAT},{LON}))
>>> print("---")
>>> print("LAT="+LAT+" LON="+LON+" vavg="+vavg(nt,{LAT},{LON}))
>>> print("---")
>>>
>>> delete( [/dp, xdp, ps, vint, dpsum/] ) ; delete temporary variables
>>>
>>>
>>>
>>>
>>>
>>> On 12/26/12 8:12 PM, Thejna Tharammal wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I want to calculate the total column mean of a variable from the CCSM
>> model
>>>> results. I tried to use dim_sum_n for the purpose as,
>>>>
>>>> ;**************************************
>>>>
>>>>
>>>> dp = dpres_hybrid_ccm (ps,p0,hyai,hybi)
>>>>
>>>> xdp=x(0,:,:,:)*dp
>>>>
>>>> vint=x(0,0,:,:)
>>>>
>>>> vint = dim_sum_n(xdp,0)
>>>>
>>>> ; for average, 1/(b-a) * integral ( from a to b ) of f(x)
>>>>
>>>> vintAvg=vint
>>>>
>>>> vintAvg =vint/dim_sum_n(dp, 0)
>>>>
>>>> ;**************************************
>>>>
>>>> I find that the results obtained are very different from the ones
>> calculated
>>>> using nco vertical integration functions ("ncwa -a lev") as a test. So
>>>> I
>>>> wonder if the
>>>> method I used is correct?
>>>>
>>>> Thanks,
>>>>
>>>> Thejna
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> ncl-talk mailing list
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>>>>
>>>
>>
>>
>

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Received on Thu Dec 27 09:38:38 2012