RE: [ferret_users] vertical weighted averagng

["Osinski, Robert FORNATL, PL" <rosinski@xxxxxxx>]

Ryo,
>With temp[x=@ave,y=@ave], Ferret does compute the area weighted average if the horizontal axes are longitude >and latitude.

So in my example the problem is that x and y axis aren't longitude and latitude. Fortunately there are data with names ULONG and ULAT which are lat and log. So the problem is how to tell ferret that x ais should be ULONG and y axis ULAT and then use @AVE to compute weighted average,
thanks,
Robert
 

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From: Ryo Furue [furue@xxxxxxxxxx]
Sent: Thursday, March 23, 2017 9:25 PM
To: Osinski, Robert FORNATL, PL
Cc: Martin Schmidt; ferret_users@xxxxxxxx
Subject: Re: [ferret_users] vertical weighted averagng

Hi Robert and Martin,

yes? list/k=1 temp[x=@ave,y=@ave]

...

      -1.788

but I'd like to have area weighed averaged value. How should I told ferret that x and y is long and lat for averaging computations,

With temp[x=@ave,y=@ave], Ferret does compute the area weighted average if the horizontal axes are longitude and latitude.  If the axes aren't longitude and latitude, Ferret computes x=@ave and y=@ave separately (I think), which may not coincide with the correct area-weighted average.

I don't know if it's possible to compute the area of each gridbox within Ferret. You may have to supply that information from outside. Then,

  let area_temp = temp * boxarea

  let area_average_temp = area_temp[x=@sum,y=@sum] / boxarea[x=@sum,y=@sum]

Ryo