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

Matt Masarik mattmasarik at boisestate.edu
Mon Jun 4 16:55:59 MDT 2018

```That's perfect.  Thanks, Dennis.

cheers,
matt

On Mon, Jun 4, 2018 at 4:50 PM, Dennis Shea <shea at ucar.edu> wrote:

> 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.
>>    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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