computing pressure from PP – in #9: CCLM

  @rolfzentek in #2b9ff43

<p> update / solution: </p> <p> For everyone having the same problem: my <strong> INT2LM setting is <code> irefatm = 2 </code> </strong> </p> <p> From looking into the source code it seems to me that that: <br/> <code> reference_atmosphere_2 </code> and thus <code> pref3 </code> is used because of my INT2LM setting <code> irefatm = 2 </code> </p> <p> I think the formula from the excel sheet and from the documentation are for the case <code> irefatm = 1 </code> </p> <p> From the documentation I get the same as from the source code: <br/> <pre> The new reference atmosphere is based on the temperature profile t0(z) = (t0sl-delta_t) + delta_t*exp(-z/h_scal), where z = hhl(k) is the height of a model grid point. </pre> <br/> From the source code <code> vgrid_refatm_utils.f90 </code> / <code> reference_atmosphere_2 </code> : <br/> <pre> The base-state pressure at main levels is computed from the analytically integrated hydrostatic equation, assuming that the height at full levels (zhfl) is the arithmetic mean of the adjacent half levels. </pre> <br/> which I interprete to be the equation <code> pref3 </code> with <code> (hhl[,,1:60]+hhl[,,2:61])/2 </code> instead of <code> vcoord </code> <br/> When I did the analytical integration of the hydrostatic equation myself I got a different formula than pref3, but they give the same values :D so in short: </p> <p> <strong> My opionion: If <code> irefatm = 2 </code> then <code> p_reference(z) = p0sl * exp( -g*h_scal/ R/t00 * log( (exp(z/h_scal)*t00 + delta_t)/(t00 + delta_t)) ) </code> </strong> <br/> with the values from my earlier posts </p>