about Thitae-s

[Greg West]

Eduardo,
    This is a script just for theta e, but it might help...

Greg

*  Calculate theta-e...a beastly job
*
*  Begin by calculating saturation vapor pressure
*       (based on equation in W+H77 problem 2.25)
*
'define satvapprs=6.11*exp(5422*((1/273.16)-(1/tmpprs)))'
*
*  Calculate saturation mixing ratio using
*    W+H77 eq. 2.65
*
'define satmixrat=0.622*satvapprs/(lev)'
*
*  Calculate RH
*
'power =
pow(10,((0.7859+0.03477*(tmpprs-273.15))/(1+0.00412*(tmpprs-273.15))+2))'
'define rhprs = 100*((lev*100)/(((0.62197*power)/spfhprs)+(0.378*power)))'
*
*  Determine the mixing ratio
*
'define mixrat=satmixrat*rhprs/100'
*
*  Calculate the vapor pressure using W+H eq. 2.65
*     with the actual mixing ratio substituted for ws
*
'define vapprs=mixrat*lev/0.622'
*
*  Calculate the dewpoint using Djuric eq. 5-13
*  Note that dewpoint from this equation is in degrees C
*
'define dewpoint=13.7*log(vapprs/6.1)'
*
*  Calculate the temperature at the LCL from
*       Djuric eq. 5-17
*  Need to convert tmpprs from K to C
*  And then add 273.16 to get tlcl in K
*
*
'define
tlcl=dewpoint-(0.001296*dewpoint+0.1963)*(tmpprs-273.16-dewpoint)+273.16'
*
*  Calculate and display theta-e based on W+H eq. 2.76
*  with w substituted for ws and Tlcl substituted for T
*
*'define thetae=tmpprs'
'define thetae=tmpprs*pow(1000/lev,0.287)*exp(2500000*mixrat/(1004*tlcl))'
return



Eduardo Agosta Scarel wrote:
 > It is not directly a Grads problem, but I need an empirical formula
 > for Thitae-s.
 > Does anybody know how to estimate the Saturation Potential Equivalent
 > Temperature and from grads??
 > Thanks a lot.
 > Eduardo.
 >
 >
*************************************************************************************************
 > Eduardo Agosta Scarel,
 > Department of Atmospheric and Oceanic Sciences, School of Sciences,
 > University of Buenos Aires and The Argentine Research and Technique
Council.
 > Pabellón II, 2do piso, Ciudad Universitaria CP 1428, Buenos Aires,
Argentina.
 >
 > phone: 05411 4576 3356, ext. 22, fax 12, e-mail: agosta at at.fcen.uba.ar

--
******************************************************
Gregory West
Graduate Research Assistant
University of Utah - Dept of Meteorology
Office: INSCC 480-10
135 S 1460 E WBB Rm. 819
Salt Lake City, UT 84112-0110
801-585-1410
gwest at met.utah.edu
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