e2ecdcfe33
Former-commit-id:a02aeb236c[formerly9f19e3f712] [formerlya02aeb236c[formerly9f19e3f712] [formerly06a8b51d6d[formerly 64fa9254b946eae7e61bbc3f513b7c3696c4f54f]]] Former-commit-id:06a8b51d6dFormer-commit-id:8e80217e59[formerly3360eb6c5f] Former-commit-id:377dcd10b9
82 lines
2.3 KiB
Python
82 lines
2.3 KiB
Python
##
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# This software was developed and / or modified by Raytheon Company,
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# pursuant to Contract DG133W-05-CQ-1067 with the US Government.
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#
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# U.S. EXPORT CONTROLLED TECHNICAL DATA
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# This software product contains export-restricted data whose
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# export/transfer/disclosure is restricted by U.S. law. Dissemination
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# to non-U.S. persons whether in the United States or abroad requires
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# an export license or other authorization.
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#
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# Contractor Name: Raytheon Company
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# Contractor Address: 6825 Pine Street, Suite 340
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# Mail Stop B8
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# Omaha, NE 68106
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# 402.291.0100
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#
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# See the AWIPS II Master Rights File ("Master Rights File.pdf") for
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# further licensing information.
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###
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## @file ThetaE.py
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#
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# Calculate equivalent potential temperature (Theta E), EPT.
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#
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# ----------------------------------------------------------------
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import gridslice
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from numpy import clip
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from numpy import exp
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from numpy import log
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from numpy import sqrt
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from numpy import power
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from numpy import zeros
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from numpy import where
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##
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# Calculate equivalent potential temperature (Theta E) from
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# pressure(mb), Temperature(degrees K) and Relative Humdity(0 to 100).
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# This function accepts numpy arrays of the appropriate values.
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#
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# @param P: Pressure in millibars
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# @param T: Temperature in degrees K
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# @param RH: Relative humidity from 0 to 100
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# @return: Equivalent potential temperature in degrees K
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# @rtype: numpy array or Python float
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#
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def execute(P,T,RH):
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"Calculate equivalent potential temperature (Theta E) from \
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presssure(mb), Temperature(degrees K) and RH(0 to 100)."
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# symbolic constants
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epsilon = 0.622
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L_cp = 2540
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# 0 to 100 is valid for RH, but we can't take log(0), so fudge value slightly
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rhqc = clip(RH,0.01,100.0)
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# do the math
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powval = -0.0091379024 * T
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powval += 22.05565
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powval -= 6106.396/T
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eee = rhqc * exp(powval)
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b = 26.66082 - log(eee)
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val = b*b
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val -= 223.1986
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val = sqrt(val)
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tdp = (b - val)
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tdp /= 0.0182758048
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val = tdp * 0.0015945203
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val += 41.178204/T
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val -= 0.37329638
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val *= T-tdp
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tc = tdp - val
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w = eee/(P - eee)
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w *= epsilon
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powval = w * L_cp
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powval /= tc
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EPT = T * exp(powval)
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EPT *= power(1000/P, 0.286)
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return EPT
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