[ncl-talk] ncep cfsr: hybrid a / hybrid a

[Dennis Shea]

Forgot:


CFSR uses:


  Pk = Ak + Bk*Psfc


NCL's pres_hybrid_ccm uses a slightly different formulation. It uses

   the formula *p = a(k)*p0 + b(k)*ps*.

The CFSR uses, *ap(k) [=a(k)*p0]*, which has units of pressure.

You must nake a(k) dimensionless prior to use.


Good luck

On Mon, Jun 4, 2018 at 4:44 PM, Dennis Shea <shea at ucar.edu> wrote:

>
>
>    You did not give any information on the source dataset you are using.
>    Hence, hard to answer.
>    Maybe the following will help:
>
>    Source: https://rda.ucar.edu/datasets/ds093.1/docs/FAQs_hrly_timeser
>    ies.html
>
>    The Climate Forecast System uses a hybrid vertical coordinate that is
>    defined by:
>       Pk = Ak + Bk*Psfc
>       where Pk is the pressure at level k, and Psfc is the surface
>       pressure
>    The values of Ak and Bk (units are Pa) are given in the following
>    table:
>       kAB
>       0 0.0 1.0
>       1 0.0 0.99467117 (This is Hybrid Level 1)
>       2 0.57499999 0.99862660
>       3 5.7410002 0.98174226
>       4 21.516001 0.97386760
>       5 55.712002 0.96482760
>       6 116.89900 0.95443410
>       7 214.01500 0.94249105
>       8 356.22299 0.92879730
>       9 552.71997 0.91315103
>       10 812.48901 0.89535499
>       11 1143.9880 0.87522358
>       12 1554.7889 0.85259068
>       13 2051.1499 0.82731885
>       14 2637.5530 0.79930973
>       15 3316.2170 0.76851469
>       16 4086.6140 0.73494524
>       17 4945.0288 0.69868290
>       18 5884.2061 0.65988702
>       19 6893.1172 0.61879963
>       20 7956.9082 0.57574666
>       21 9057.0508 0.53113484
>       22 10171.712 0.48544332
>       23 11276.348 0.43921080
>       24 12344.490 0.39301825
>       25 13348.671 0.34746850
>       26 14261.435 0.30316412
>       27 15056.342 0.26068544
>       28 15708.893 0.22057019
>       29 16197.315 0.18329623
>       30 16503.145 0.14926878
>       31 16611.604 0.11881219
>       32 16511.736 0.092166908
>       33 16197.967 0.069474578
>       34 15683.489 0.050646842
>       35 14993.074 0.035441618
>       36 14154.316 0.023555880
>       37 13197.065 0.014637120
>       38 12152.937 0.082940198
>       39 11054.853 0.041067102
>       40 9936.6143 0.016359100
>       41 8832.5371 0.0043106001
>       42 7777.1499 0.00036969999
>       43 6804.8740 0.0
>       44 5937.0498 0.0
>       45 5167.1460 0.0
>       46 4485.4932 0.0
>       47 3883.0520 0.0
>       48 3351.4600 0.0
>       49 2883.0381 0.0
>       50 2470.7881 0.0
>       51 2108.3660 0.0
>       52 1790.0510 0.0
>       53 1510.7111 0.0
>       54 1265.7520 0.0
>       55 1051.0800 0.0
>       56 863.05798 0.0
>       57 698.45697 0.0
>       58 554.42401 0.0
>       59 428.43399 0.0
>       60 318.26599 0.0
>       61 221.95799 0.0
>       62 137.78999 0.0
>       63 64.247002 0.0
>       64 0.0 0.0
>
>
> On Mon, Jun 4, 2018 at 2:33 PM, Matt Masarik <mattmasarik at boisestate.edu>
> wrote:
>
>> I'm interested in plotting PV on isentropic surfaces from the NCEP CFSRR
>> (reforecast) data set.  I'm planning to interpolate variables to isentropes
>> using (http://www.ncl.ucar.edu/Applications/Scripts/isent_1.ncl) and
>> then calculate PV on those surfaces using (http://www.ncl.ucar.edu/Docum
>> ent/Functions/Contributed/pot_vort_hybrid.shtml).
>>
>> A helper function in there (pres_hybrid_ccm) requires Hybrid A and Hybrid
>> B coefficients for mid- model levels.  I haven't been able to find anything
>> for these constants in CFS on www..  Can someone point me to how I can find
>> these?
>>
>> Thank you,
>> Matt
>>
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>
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