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Hi Rolf, I send you an excel table for the case of 40 levels, which was prepared by H-J and myself in order to analyse the inconsistencies between the grid definitions in COSMO . It shows all related quantities of the reference atmosphere and the same values as in YUSPECIF . You may adapt it for 60 levels and compare the formula with yours. This should give the correct values. I’m sorry, but I do not have the time at the moment to check it on my own. Regards, Andreas Rolf Zentek wrote: > Hi, > > I have my 3d (+time = 4d) variable PP (deviation from reference pressure). > Now I simple want to compute my pressure on the full levels. > > from YUSPECIF: > > Vertical coordinate: type 2 (Gal-Chen hybrid) > k Z(k) P0(k) > 1 25000.0000 28.1726 > 2 23800.0000 33.9524 > […..] > 60 10.0000 998.8149 > 61 0.0000 1000.0000 > Boundary for change from z to terrain-following: vcflat = 11430.0000 > Half-level index where levels become flat: k = 15 > Exponential profile with asymptotic isothermal stratosphere > Values of the Reference Atmosphere: > Pressure at Sea-Level: 1000.0000 > Temperature at Sea-Level: 15.0000 > Temp. diff. sea-level-stratosph.: 75.0000 > Scale height for temp. decrease: 10000.0000 > > from Output constant file (lffd2015123118c.nc) > > vcoord:long_name = “Height-based hybrid Gal-Chen coordinate” ; > vcoord:units = “Pa” ; > vcoord:ivctype = 2 ; > vcoord:irefatm = 2 ; > vcoord:p0sl = 100000. ; > vcoord:t0sl = 288.149993896484 ; > vcoord:dt0lp = 42. ; > vcoord:vcflat = 11430. ; > vcoord:delta_t = 75. ; > vcoord:h_scal = 10000. ; > > As I understand it, I need to compute the reference pressure for every grid point and then just add PP? > I must compute the reference pressure on full levels right? > > Step 1: H = ( HLL[:,:,1:60] + HLL[:,:,2:61] ) * 0.5 > Step 2: P_ref = specialFunction(H) = “pressure in Height H“ > Step 3: P = P_ref + PP > > Is this so far correct? > In that case what is this “specialFunction”? (I know it is basically barometric height formula… but which version?) > I tried the formula from the COSMO Documentation (Part I: Dynamics and Numerics) page 28/29, equation (3.85) > p_0(z) = … for both cases beta = 0 and beta = 42 > but if I test it with the values from YUSPECIF I get lower or higher values than there. > > nc = nc_open(file) > vcoord = ncvar_get(nc,“vcoord”) > p0sl = ncatt_get(nc,“vcoord”,“p0sl”)$value > t0sl = ncatt_get(nc,“vcoord”,“t0sl”)$value > dt0lp = ncatt_get(nc,“vcoord”,“dt0lp”)$value > pref1 = p0sl * exp( -t0sl/dt0lp * (1-sqrt(1 – 2 * dt0lp * 9.81 * vcoord / 287.058 / t0sl^2) ) > pref2 = p0sl * exp( -9.81 * vcoord / 287.058 / t0sl ) > > for 25000m > pref1 gives 13 hPa > pref2 gives 51 hPa > while YUSPECIF says 28 hPa > > Any suggestions? > Rolf > > P.S.: the attribute:units of the variable “vcoord” says “Pa” but its obviously(?) meter > > edit: I attached the files

#c06172b

@andreaswill in #c06172b
 Hi Rolf, I send you an excel table for the case of 40 levels, which was prepared by H-J and myself in order to analyse the inconsistencies between the grid definitions in COSMO . It shows all related quantities of the reference atmosphere and the same values as in YUSPECIF . You may adapt it for 60 levels and compare the formula with yours. This should give the correct values. I’m sorry, but I do not have the time at the moment to check it on my own. Regards, Andreas Rolf Zentek wrote: > Hi, > > I have my 3d (+time = 4d) variable PP (deviation from reference pressure). > Now I simple want to compute my pressure on the full levels. > > from YUSPECIF: > > Vertical coordinate: type 2 (Gal-Chen hybrid) > k Z(k) P0(k) > 1 25000.0000 28.1726 > 2 23800.0000 33.9524 > […..] > 60 10.0000 998.8149 > 61 0.0000 1000.0000 > Boundary for change from z to terrain-following: vcflat = 11430.0000 > Half-level index where levels become flat: k = 15 > Exponential profile with asymptotic isothermal stratosphere > Values of the Reference Atmosphere: > Pressure at Sea-Level: 1000.0000 > Temperature at Sea-Level: 15.0000 > Temp. diff. sea-level-stratosph.: 75.0000 > Scale height for temp. decrease: 10000.0000 > > from Output constant file (lffd2015123118c.nc) > > vcoord:long_name = “Height-based hybrid Gal-Chen coordinate” ; > vcoord:units = “Pa” ; > vcoord:ivctype = 2 ; > vcoord:irefatm = 2 ; > vcoord:p0sl = 100000. ; > vcoord:t0sl = 288.149993896484 ; > vcoord:dt0lp = 42. ; > vcoord:vcflat = 11430. ; > vcoord:delta_t = 75. ; > vcoord:h_scal = 10000. ; > > As I understand it, I need to compute the reference pressure for every grid point and then just add PP? > I must compute the reference pressure on full levels right? > > Step 1: H = ( HLL[:,:,1:60] + HLL[:,:,2:61] ) * 0.5 > Step 2: P_ref = specialFunction(H) = “pressure in Height H“ > Step 3: P = P_ref + PP > > Is this so far correct? > In that case what is this “specialFunction”? (I know it is basically barometric height formula… but which version?) > I tried the formula from the COSMO Documentation (Part I: Dynamics and Numerics) page 28/29, equation (3.85) > p_0(z) = … for both cases beta = 0 and beta = 42 > but if I test it with the values from YUSPECIF I get lower or higher values than there. > > nc = nc_open(file) > vcoord = ncvar_get(nc,“vcoord”) > p0sl = ncatt_get(nc,“vcoord”,“p0sl”)$value > t0sl = ncatt_get(nc,“vcoord”,“t0sl”)$value > dt0lp = ncatt_get(nc,“vcoord”,“dt0lp”)$value > pref1 = p0sl * exp( -t0sl/dt0lp * (1-sqrt(1 – 2 * dt0lp * 9.81 * vcoord / 287.058 / t0sl^2) ) > pref2 = p0sl * exp( -9.81 * vcoord / 287.058 / t0sl ) > > for 25000m > pref1 gives 13 hPa > pref2 gives 51 hPa > while YUSPECIF says 28 hPa > > Any suggestions? > Rolf > > P.S.: the attribute:units of the variable “vcoord” says “Pa” but its obviously(?) meter > > edit: I attached the files

computing pressure from PP – in #9: CCLM

in #9: CCLM

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