[gradsusr] area and vertical average

[Jennifer M Adams]

Hi, Sim —
It’s much more efficient to use aave() instead of nested  ave() functions over X and Y. Start by setting Z varying and define your area averages at desired levels.  The ‘define’ command will calculate the area averages at each fixed Z level and then stack them into a Z-varying result — it is the equivalent of having a zloop() function under the hood.

‘set x 1'
‘set y 1'
‘set lev 925 700’
‘define uave = aave(ugrdprs,x=1,x=463,y=1,y=425)’

Now fix Z and average over all levels:

‘set z 1'
‘define val = ave(uave,lev=925,lev=700)’

—Jennifer





On May 8, 2019, at 4:36 PM, sim.aberson <sim.aberson at noaa.gov<mailto:sim.aberson at noaa.gov>> wrote:

I wish to calculate the area average of a variable that is vertically averaged between two levels.  I use the command:

'define aveu=ave(ave(ave(ugrdprs,x=1,x=463),y=1,y=425),lev=925,lev=700)'

This seems to take a huge amount of time (a half hour and counting on my mac).  Even without the vertical average, for example,

'd ave(ave(wtmpsfc,x=1,x=463),y=1,y=425)'

takes about 3 minutes.  However, just issuing the command

'define u850=ave(ugrdprs,lev=925,lev=700)'

returns the result in just a moment.

Am I doing this wrong?  Is there a more efficient way that I am overlooking?

Thanks,
Sim Aberson
NOAA/AOML/Hurricane Research Division

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--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University



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