HPIES Instrument Being Deployed
HPIES at Slope Base

The HPIES instrument at 2900 m water depth as it is about to be recovered by the ROV ROPOS during Leg 2 of the VISIONS'15 expedition. Credit: NSF-OOI/UW/ISS; V15.

HPIES Installed at Slope Base

The Horizontal Electrometer-Pressure-Inverted Echosounder (HPIES -HPIESA101) installed at the Slope Base site. Photo credit: NSF-OOI/UW/CSSF; Dive R1757; V14.  

The Horizontal Electrometer-Pressure-Inverted Echosounder (HPIES), are novel instruments designed at built at the UW Applied Physics Laboratory. They utilize a bottom pressure sensor, a 12-kHz inverted echosounder and a horizontal electrometer to measure the horizontal electrical field, the pressure due to the overlying ocean waters, and the vertical acoustic travel time from the seafloor to the sea surface. These properties provide insights into the vertical structure of current fields and water properties including temperature, salinity, and specific volume anomaly, separation of sea surface height variation and temperature, and near-bottom water currents.

There are two HPIES instruments on the Cabled Array - one at Axial Base (LJ03A) and one at Slope Base (LJ01A).