Re: The depth at which dT/dz is maximum...

[<Mick.Spillane@xxxxxxxx>]

On Mon, 24 Jan 2005, Seontae Kim wrote:

> I am trying to calculate the depth where the vertical derivative of
> temperature, dT/dz, is maximum with ocean temperature data using Ferret. Is
> it possbile? Could you anyone help me with it ?
Hi Seon Tae Kim,
	The following is something I have used to get the "thickness"
of the temperature at the bottom of the mixed layer.  It assumes
the data are on an evenly-spaced z-axis so that central difference
makes sense ( let dtdz = t_20[z=@ddc] , where t_20 is a temperature
variable). Then you search dtdz for the (negative) peak, and in my
case define the thickness as the "width-at-half-maximum" of the peak.
Good luck,
Mick
!
! width_half_max : lists the separation of the points at which dT/dz
!                  is half of its peak (negative) value
def sym peak  `dtdz[z=@min]`         ! the peak negative value of
                                     !  dtdz = t_20[z=@ddc]
def sym zpeak `dtdz[z=@loc:($peak)]` ! zpeak is the depth at which
                                     ! the peak gradient occurs
def sym zmax  `zz[z=@max]`           ! is the maximum depth of the
                                     ! depth axis zz = z[g=grd]
def sym half `($peak) / 2`           ! defines half maximum
let z1 = dtdz[z=0:($zpeak)@loc:($half)]
let z2 = dtdz[z=($zpeak):($zmax)@loc:($half)]
list z1,z2,z2-z1

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