amax()
This function returns an area maximum -- the maximum value in a grid spanning an X-Y region. The syntax is:
amax(expr, xdim1, xdim2, ydim1, ydim2)
where:
expr
any valid grads grid expression
xdim1
starting X or LON dimension expression
xdim2
ending X or LON dimension expression
ydim1
starting Y or LAT dimension expression
ydim2
ending Y or LAT dimension expression
For global maximum, a shorthand may be used:
amax(expr, global)
or
amax(expr, g)
is the same as
amax(expr, lon=0, lon=360, lat=-90, lat=90)
Usage Notes
- This function will only work with grads version 2.0.2 or later.
-
This function is more efficient that using nested
max
functions. -
Related functions
amaxlocx
andamaxlocy
will return the grid location (X or Y) of the maximum value. If more than one grid box contains the maximum value, the location returned will be the first one encountered as the grid is scanned. The grid is scanned by rows from south to north, and each row is scanned from west to east. -
A similar set of functions exists for finding the minimum over an area:
amin
,aminlocx
, andaminlocy
.
Examples
-
Get the maximum value of the variable
ps
over a specified grid domain:d amax(ps,x=10,x=120,y=15,y=45)
-
Get the maximum value of the variable
sstanom
over the nino3.4 domain:d amax(sstanom,lon=-170,lon=-120,lat=-5,lat=5)
-
Get the maximum value of the variable
slp
over the global domain, and also get the grid location of that minimum. Check results.ga-> d amax(slp,g)Result value = 105732ga-> d amaxlocx(slp,g)ga-> d amaxlocy(slp,g)Result value = 168 Result value = 13ga-> set y 13ga-> set x 168 LON set to 83.5 83.5