Ben Brockert on Nostr: Anyone have a good explanation of this figure? My interpretation is that they are ...

Anyone have a good explanation of this figure? My interpretation is that they are using the width between the slanted line and the vertical line to mean the pressure at that depth. I just don't understand why you'd do that on the negative side of the vertical axis and why you wouldn't label it. Maybe it's standard in that field?

https://geo.libretexts.org/Bookshelves/Oceanography/Coastal_Dynamics_(Bosboom_and_Stive)/05%3A_Coastal_hydrodynamics/5.04%3A_Wave_orbital_velocity_pressure_and_bed_shear_stress/5.4.2%3A_Dynamic_Pressure