Abstract:
Two Autonomous Underwater Vehicle Gliders have alternated continuous
sampling of a 45-nautical mile transect line (the Newport Hydrographic Line) across
the Oregon continental shelf since April, 2006. Strong currents (>25cm/s) push the
gliders off their trajectories as they survey this transect line, preventing them from
sampling the historically occupied stations exactly. Three methods were used to
map the semi-regular glider data onto a cross-shelf line: (1) an algorithm that groups
data by isobaths then block-averages the data, (2) an objective analysis that employs
fixed along-isobath and cross-isobath correlation scales, and (3) a hybrid
combination of the isobath-binning algorithm and objective analysis. To determine
validity and accuracy, the mapping procedures are tested by comparison to moored
observations at NH-10 on the Newport Line in 80m water depth while varying the
spatial and temporal averaging scales. Isobath binning showed the best agreement
with moored observations at the monthly timescale, while objective analysis showed
the best agreement with moored observations at the weekly timescale. The hybrid
method improved the agreement of the objective analysis at larger timescales.
