ADCP Mooring Sites
Cockburn Sound, Western Australia
Sites span 6–20 m depth
ADCP Data Window Coverage
42 site–window combinations assessed across 8 windows.
| Window | Period | Days | CS1 | CS2 | CS3 | CS4 | CS5 | CS6 | CS7 |
|---|---|---|---|---|---|---|---|---|---|
| W0 Autumn Transition | 2021-04-16 – 2021-06-10 | 55 | — | ✓ | ✓ | — | — | — | — |
| W1 Summer Sea-Breeze | 2021-11-22 – 2021-12-06 | 14 | — | ✓ | ✓ | ✓ | ✓ | ✓ | — |
| W2 Northerly then Sea-Breeze | 2021-12-06 – 2021-12-18 | 12 | — | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| W3 Late Summer | 2022-02-01 – 2022-02-15 | 14 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| W4 Easterly Component | 2022-02-15 – 2022-03-01 | 14 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| W5 Post-Cyclone CSW | 2022-03-22 – 2022-04-07 | 16 | ✓ | — | ✓ | ✓ | ✓ | ✓ | — |
| W6 Storm-Driven Renewal | 2022-06-15 – 2022-06-29 | 14 | ✓ | — | ✓ | ✓ | ✓ | ✓ | — |
| W7 Leeuwin Current | 2022-06-29 – 2022-07-13 | 14 | ✓ | — | ✓ | ✓ | ✓ | ✓ | — |
W02021-04-16 – 2021-06-10
W12021-11-22 – 2021-12-06
W22021-12-06 – 2021-12-18
W32022-02-01 – 2022-02-15
W42022-02-15 – 2022-03-01
W52022-03-22 – 2022-04-07
W62022-06-15 – 2022-06-29
W72022-06-29 – 2022-07-13
W0: Autumn Transition
- Autumn transition: progressive cooling 22 °C → 18 °C with intermittent calm periods
- SW wind events (12–14 m/s) punctuate calm spells, driving rapid full-depth mixing
- Shift from light easterlies toward winter wind regime
- Baseline test at two deep basin sites (CS2, CS3) during seasonal transition
Model notes: Uses 2021B simulation (separate year to W1–W7). Model reproduces stratification–destratification cycles during intermittent calm/wind periods. DWER profiling mooring comparisons confirm model slightly overestimates upper-column temperature; timing of cooling events well captured. CS3 persistent directional offset in lower water column already apparent.
CS6 not available
CS2 (20m) — Basin (mid-west)
CS4 not available
CS7 not available
CS3 (20m) — Basin (south)
W1: Summer Sea-Breeze
- Established diurnal sea-breeze pattern; S/SW winds dominate (69%), 8–12 m/s afternoons
- Regular two-layer flow: wind-driven northward surface over southward bottom return
- Model captures phasing and depth of velocity reversal with good fidelity
- Purest sea-breeze forcing window of the campaign
Model notes: Good fidelity in diurnal reversal phasing and depth of velocity shear at all sites. Near-bottom observed speeds occasionally exceed model during strongest sea-breeze events. CS3 shows persistent directional offset in lower water column. CS6 (Owen Anchorage) observed directional variability broader than modelled — local reef/coastal geometry effects not fully resolved by mesh.
CS6 (11m) — Owen Anchorage
CS1 not available
CS5 (11m) — Shelf (north)
CS2 (20m) — Basin (mid-west)
CS4 (11m) — Shelf (south)
CS7 not available
CS3 (20m) — Basin (south)
W2: Northerly then Sea-Breeze
- S/SW dominates (52%) with single 26-hour northerly event (~9 Dec)
- CS7 (Causeway) site comes online — strong tidal signal through the constriction
- Diurnal current reversals continue; model maintains good speed and reversal agreement
- Broadens validation to include Garden Island Causeway exchange
Model notes: CS7 (Causeway) tidal phasing well captured by model; +96° compass correction applied to EcoADCP aligns observed directions with model’s along-channel flow axis. CS3 directional offset persists, confirming systematic feature. CS4 and CS5 records end mid-window (instruments recovered ~10–13 Dec).
CS6 (11m) — Owen Anchorage
CS1 not available
CS5 (11m) — Shelf (north)
CS2 (20m) — Basin (mid-west)
CS4 (11m) — Shelf (south)
CS7 (6m) — Causeway
CS3 (20m) — Basin (south)
W3: Late Summer
- S/SW still dominant (53%) but diurnal cycle less regular; brief NE interruptions
- Full 7-site coverage enables assessment of anti-clockwise bottom gyre structure
- Model captures directional shifts during NE events; some surface speed underestimation
- Persistent directional offset at CS3 (southern basin)
Model notes: Most spatially complete window (all 7 sites). Model captures timing of directional shifts during brief NE events but near-surface speed intensification slightly exceeds modelled values. CS3 directional offset persists and model overestimates directional coherence at this site — suggests local bathymetric steering the B-mesh does not fully resolve. Bottom gyre vectors show anti-clockwise pattern consistent with D’Adamo summer regime.
CS6 (11m) — Owen Anchorage
CS1 (20m) — Basin (north)
CS5 (11m) — Shelf (north)
CS2 (20m) — Basin (mid-west)
CS4 (11m) — Shelf (south)
CS7 (6m) — Causeway
CS3 (20m) — Basin (south)
W4: Easterly Component
- S/SE/E winds dominate (72%); sea-breeze pattern persists with more E/SE component
- Two-layer structure maintained with episodes of stronger near-surface intensification
- Model captures overall pattern; slight underestimation of peak speeds
- Comparison with W3 gyre pattern tests response to modified wind regime
Model notes: Episodes of stronger near-surface intensification (>0.25 m/s) at CS1 that model tends to underestimate — possibly modified wind fetch under easterly conditions. CS4 deployment ends mid-window (~20 Feb). Bottom gyre comparison with W3 tests whether residual pattern shifts under modified wind regime despite similar overall forcing — may indicate evolving basin–shelf density contrasts.
CS6 (11m) — Owen Anchorage
CS1 (20m) — Basin (north)
CS5 (11m) — Shelf (north)
CS2 (20m) — Basin (mid-west)
CS4 (11m) — Shelf (south)
CS7 (6m) — Causeway
CS3 (20m) — Basin (south)
W5: Post-Cyclone CSW
- TC Charlotte CSW: ~0.2–0.25 m sub-tidal peak arrives ~28 Mar
- Winds predominantly E/SE (64%); barotropic pressure gradients drive enhanced exchange at CS1
- Model captures CSW timing and amplitude via open boundary forcing
- Depth-uniform flow on shallow shelf sites during weak local wind
Model notes: Open boundary forcing (WA-ROMS) successfully transmits CSW signal into the CSIEM domain. CS1 observed near-surface speeds slightly exceed model during strongest exchange events. CS3 persistent directional offset continues — bathymetric steering effect at southern basin not fully captured by B-mesh. CS4/CS5 barotropic response well reproduced; CS6 some directional discrepancies in lower water column.
CS6 (11m) — Owen Anchorage
CS1 (20m) — Basin (north)
CS5 (11m) — Shelf (north)
CS2 not available
CS4 (11m) — Shelf (south)
CS7 not available
CS3 (20m) — Basin (south)
W6: Storm-Driven Renewal
- Three sustained northerly episodes (33–47 h, 6–8 m/s); peak storm >15 m/s
- Storm drives full-depth mixing; post-storm recovery shows re-establishment of two-layer flow
- Deep-water renewal inflows detected at CS1 (northern opening)
- First window to clearly sample D’Adamo winter–spring storm-driven renewal regime
Model notes: Model captures both storm intensification and post-storm recovery of vertical shear. Observed near-bottom speeds during calm aftermath suggest stronger deep renewal inflow than model produces at CS1. CS3 storm-driven bottom-intensified current pulses captured in timing but model vertical structure smoother than observed. CS6 shows different recovery pattern to basin sites — directional variability remains broad, reflecting open exposure to regional shelf processes.
CS6 (11m) — Owen Anchorage
CS1 (20m) — Basin (north)
CS5 (11m) — Shelf (north)
CS2 not available
CS4 (11m) — Shelf (south)
CS7 not available
CS3 (20m) — Basin (south)
W7: Leeuwin Current
- Peak Leeuwin Current influence; sustained elevated regional water levels
- N/NE winds dominate (46%); persistent bottom-intensified baroclinic currents
- Model captures elevated sub-tidal level and baroclinic exchange character
- Contrast with W6 tests model’s shift from barotropic to baroclinic forcing
Model notes: Despite weak local wind, observed current field remains energetic — bottom-intensified currents at CS1 (~0.15–0.20 m/s) exceed modelled values during several multi-day episodes, suggesting model underestimates density-driven inflow under peak LC conditions. CS6 shows persistent southward flow consistent with regional LC influence; model captures general speed level but some directional timing differences. Shift from W6 (barotropic) to W7 (baroclinic) residual pattern provides stringent test of model forcing-mode transition.
CS6 (11m) — Owen Anchorage
CS1 (20m) — Basin (north)
CS5 (11m) — Shelf (north)
CS2 not available
CS4 (11m) — Shelf (south)
CS7 not available
CS3 (20m) — Basin (south)
Data Source & Notes
The ADCP current profile observations were collected as part of WAMSI Westport Marine Science Program, Project 5.1 (Multi-decadal ocean boundary conditions and field measurements), led by Prof Charitha Pattiaratchi and data curated by Tanziha Mahjabin, from the University of Western Australia (UWA). Seven bottom-mounted, upward-looking ADCPs were deployed across Cockburn Sound between April 2021 and August 2022, providing vertical current profiles at 0.15–0.50 m vertical resolution and 2–20 minute sampling intervals.
- Out-of-water filtering — timesteps where pressure sensor depth < 1 m are masked.
- Sidelobe contamination masking — cells above
PSD × cos(beam_angle)set to NaN. - Speed threshold — current speeds exceeding 2.0 m/s are masked as physically implausible.
- Timezone alignment — ADCP timestamps (UTC) shifted +8 h to AWST.
- Vertical datum — metres relative to Australian Height Datum (mAHD).
- CS7 Eco ADCP direction correction (+96°) — systematic compass offset applied to both Eco ADCP deployments.
- CS7 Aquadopp HR excluded — June 2022 deployment has different offset and limited coverage.
Model: CSIEM1.7.0 — 2021B (W0) and 2022B (W1–W7) TUFLOW-FV runs. Speed colourmap fixed at 0–0.3 m/s. Direction uses the twilight_shifted cyclic colourmap (towards convention, °N).
