Now use FDD$,$ BDD$,$ or CDD $($whichever is appropriate$)$ to find the $1$st and $2$nd

derivative of Temperature $($T$)$ with respect to depth $($z$)$ with $($

$$

$).$

Plot these results separately, and locate the thermocline from $$

$2/$

$2$ plot. $($Formulations

for FDD$,$ BDD$,$ and CDD are given in Figures $21\mathrm{.}3,21\mathrm{.}4,$ and $21\mathrm{.}5,$ respectively$).$

Remember Thermocline is at a depth where $($

$2/$

$2$

$)=0$