>Hello. In example moc_3.ncl on the NCL website, if I want to plot
>simply the Pacific overturning, is it OK to just use:
>
> zone_int(j,k) = dim_sum(v(k,j,42:103)*cos(lat(j)*d2rad)*dx*dz(k))
>
> (for 120E-290E) ??
>
>The plot seems a bit peculiar, with a band of negative values extending down
>from the sfc around 30N.
===================
original code from example
http://www.ncl.ucar.edu/Applications/Scripts/moc_3.ncl
;**************************************************************
; calculate first intergral
; int[lon1:lon2]v*cos(lat)*dx*dz
; this calculation is done on the z_t grid
;**************************************************************
zone_int = new((/nlat,nlev/),typeof(v)) ; allocate space
do k = 0, nlev-1
do j = 0, nlat-1
zone_int(j,k) = dim_sum(v(k,j,:)*cos(lat(j)*d2rad)*dx*dz(k))
end do
end do
========================
What u did [above] looks ok to me.
[1] at each j,k
cos(lat(j)*d2rad)*dx*dz(k) [=constant]
is just a constant
The above reduces to
zone_int(j,k) = dim_sum(v(k,j,42:103)*constant)
or
zone_int(j,k) = dim_sum(v(k,j,42:103))*constant
All u r doing is at each k,j is summing "v" the longitudes
and multiplying by the cosinf(lat) [area] and
delta-s [ie layer thickness]
[2] Over the global range of longitudes you would
expect the net meridional wind [v] to be ~zero.
When this is done over a limited area, this is not
the case. you are looking at a regional "v"
D
from original script
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