`fndlvl (`

*expr, expr_to_find, lev1, lev2*)

Given two gridded variables,

and
*expr*

, this function finds the first
vertical level at which the *expr_to_find*

value
occurs in *expr_to_find*

. *expr*

and
*lev1*

specify the range of
levels over which to search. The result is a grid of pressure values.
*lev2*

- The dimensions of

and*expr*

must match.*expr_to_find*

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

- The

doesn't have to be a constant; it can change with location. This example returns the pressure level of the tropopause, given the variable*expr_to_find*`'ttrop'`

that contains the temperature at the tropopause:`d fndlvl (t, ttrop, lev=1000, lev=100)`

- 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`

`.`