The jerk dip is a partial jerk exercise to strengthen the dip position—in particular the ability to arrest the downward movement of the weight in order to drive back up. It is not the same as a jerk dip squat.
 
Stand in your jerk drive stance with the bar in the jerk rack position. Brace your trunk as you would for a jerk, then dip exactly as you do for a jerk, but move down as quickly as possible—don’t worry too much about losing connection to the bar slightly.
 
Brake in the bottom as abruptly as possible and hold for a moment to let the bar oscillate. The goal is to create maximal downward force and then stop it as quickly as possible while remaining in a perfect dip position. Return to standing at a natural speed.
 
Notes
The speed at which you dip in this exercise may exceed the speed at which you dip during an actual jerk depending on your jerk style. This is intentional in order to create more downward force for the legs to absorb and arrest.
 
Purpose
The jerk dip is intended to strengthen the bottom of the dip and train the legs to absorb the downward force in order to better transition and drive from the bottom of the dip in the jerk.   
 
Programming
The jerk dip can be performed in isolation from a rack or blocks for 1-5 reps, combined with cleans or front squats, or performed for 1-3 reps prior to one or more jerks. Weights can be very heavy and exceed the lifter’s maximum jerk as long as the position and balance are correct.