fndlvl()

fndlvl (expr, expr_to_find, lev1, lev2)

Given two gridded variables, expr and expr_to_find, this function finds the first vertical level at which the expr_to_find value occurs in expr. lev1 and lev2 specify the range of levels over which to search. The result is a grid of pressure values.

Usage Notes

1. The dimensions of expr and expr_to_find   must match.

Examples

1. This example finds the pressure levels of the 240 degree isotherm:
   d fndlvl (t, const(t,240), lev=1000, lev=100)

2. The expr_to_find doesn't have to be a constant; it can change with location. This example returns the pressure level of the tropopause, given the variable 'ttrop' that contains the temperature at the tropopause:
   d fndlvl (t, ttrop, lev=1000, lev=100)

3. This example illustrates the limitations of fndlvl. It returns the level of the surface pressure variable psfc in the coordinate system of lev, a GrADS pre-defined variable.
   d fndlvl (lev, psfc, lev=1000, lev=100)

   The display should be exactly the same as psfc except in locations where psfc is greater than 1000 mb, the maximum value of lev.