Pressure/height vs. latitude

From: Nicholas Herold <nher5224_at_nyahnyahspammersnyahnyah>
Date: Mon, 29 Oct 2007 13:28:10 +1100

Hi,

I am trying to convert CCSM hybrid coordinates to pressure coordinates
(which I think I have done successfully) and then plot them in a
pressure/height vs. latitude plot.

When I look at the output the values seem normal however the white space
that represents land at the bottom of the plot appears incorrect. There is
land where there shouldn't be and vice versa. I have tried several
longitudes, some look more correct than others, I have also tried plotting
via index values and longitude values, both appear incorrect. Is there a
weighting or interpolation issue I should be aware of when doing a plot of
this sort?

Here are the relevent sections, I've also attached a sample plot, you can
see from the longitude that the white spaces do not appear correctly (e.g.
Antarctica seems to go to 40deg. S);

variable_complete=new((/3,26,48,96/),"float")
variable_complete(0,:,:,:)=f1->\$var\$(:,:,:)
variable_complete(0,:,:,:)=f1->\$var\$(:,:,:)

variable_complete(1,:,:,:)=f2->\$var\$(:,:,:)
variable_complete(1,:,:,:)=f2->\$var\$(:,:,:)

variable_complete(2,:,:,:)=variable_complete(0,:,:,:) -
variable_complete(1,:,:,:)
variable_complete(2,:,:,:)=variable_complete(0,:,:,:) -
variable_complete(1,:,:,:)

.....

; initialise interpolation variables
hyam = f1->hyam ; hybrid a coefficients
hybm = f1->hybm ; hybrid b coefficients
pressure_levels = (/ 1000.0,850.0,700.0,500.0,300.0,200.0,100.0 /)
PS = f1->PS ; surface pressure of dataset
interp = 2 ; type of interpolation: 1 = linear, 2 = log, 3 = loglog
P0mb = 1000 ;f1->P0*0.01 ; surface pressure
ii = 1 ; not used at this time, set to 1
kxtrp = False ; no extrapolation when the pressure level is outside of
the range of PS (False)
pressure =
vinth2p(variable_complete(c,:,:,:),hyam,hybm,pressure_levels,PS(:,:),interp,P0mb,1,kxtrp)

pressure&lev_p_at_units = "mb"
tmplon = stringtofloat(longitude)
plot(c) =
gsn_csm_pres_hgt(wks,pressure(:,:,{stringtofloat(longitude)}),resources)
delete(pressure)

Nicholas.

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Received on Sun Oct 28 2007 - 20:28:10 MDT

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