amin()

This function returns an area minimum -- the minimum value in a grid spanning an X-Y region. The syntax is:

amin(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 minimum, a shorthand may be used:

amin(expr, global) or
amin(expr, g)

amin(expr, lon=0, lon=360, lat=-90, lat=90)

Usage Notes

1. This function will only work with GrADS version 2.0.2 or later.
2. This function is more efficient that using nested min functions.
3. Related functions aminlocx and aminlocy will return the grid location (X or Y) of the minimum value. If more than one grid box contains the minimum 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.
4. A similar set of functions exists for finding the maximum over an area: amax, amaxlocx, and amaxlocy.

Examples

1. Get the minimum value of the variable ps over a specified grid domain:
   d amin(ps,x=10,x=120,y=15,y=45)
   
   
2. Get the minimum value of the variable sstanom over the nino3.4 domain:
   d amin(sstanom,lon=-170,lon=-120,lat=-5,lat=5)
   
   
3. Get the minimum value of the variable slp over the global domain, and also get the grid location of that minimum. Check results.
   

   ga-> d amin(slp,g)     
   Result value = 94569 
   ga-> d aminlocx(slp,g)
   Result value = 523 
   ga-> d aminlocy(slp,g)
   Result value = 51 
   ga-> set x 523
   LON set to 261 261 
   ga-> set y 51
   LAT set to -65 -65 
   ga-> d slp
   Result value = 94569