This function returns the Y location of minimum grid value over a spatial domain. The syntax is:
 aminlocy(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 the Y location of the global minimum, a shorthand may be used:
aminlocy(expr, global) or aminlocy(expr, g)
aminlocy(expr, lon=0, lon=360, lat=-90, lat=90)
minloc and min functions. 
aminlocx will return the X  location of the minimum grid value. 
amin function to retrieve the minimum value over the grid.  
amax, amaxlocx, and amaxlocy.
amin.