J.R. Marko and D.B. Fissel ASL Environmental Sciences Inc. Sidney B.C. Canada

Martin Jasek BC Hydro Ltd.

ASL Shallow Water Ice Profiler SWIP-5

Concrete Pad

Instrument Shack

Ice

10m max

ElectronicsCable

SWIP Transducer

Anchor line

Ice

InstrumentCabinet

Peace River Acoustic Studies initiated in Nov.2004 to monitor ice growth with the SWIPS (Shallow Water Ice Profiling Sonar), a shore-based, realtime version of ASL’s IPS a marine Upward Looking Sonar profiler

Operated by recording returns of 235 kHz acoustic pulses to detected ranges to ice undersurface to estimate draft (with aid of hydrostatic and atmospheric pressure data)

Self-Contained Deployment Configuration

SWIP Pressure Housing / Transducer

Figure 1. SWIP components (1) Persistor Computing Module (2) Pressure Port (3) Serial Data Cable Connector (4) Transducer Connector (5) Transducer Face (6) Latch (one of two) (7) Zinc anode (8) Transducer Mounting Plate (Stainless Steel) (9) Polycarbonate Pressure Case (10) Orientation Guide (face of transducer points towards the

water surface)

1.1 Specifications

Shore power requirement: 8-15V, 90 mA nominal current draw (or optional submersible external battery pack). Range: 1 to 20 m Water Temperature: 0 to 4 °C ± 1 °C and 4 to 10 °C ± 2 °C Tilt Useful range: ± 45 degrees on both axis. Tilt Accuracy: ± 0.1° over the range of ± 20 degrees on both axis Accuracy on range: ±0.05 m. The accuracy of ice draft depends on existing water level sensor. Standard output signal: RS-422

IPS5Link Software

Acoustic Range and Ice Draft Data

2004-5 results showed both significant internal structure in ice cover AND evidence of weak detection of frazil particles in water column

Frazil returns relatively uniform or even bottom weighted in water column in supercooling intervals prior to ice cover formation BUT concentrated in upper 1 m late in ice covered season

2004-5 results and BC Hydro’s interests in water column frazil motivated adjacent 2005-6 deployments of the 235khz (SWIPS1) and a higher frequency (545 kHz) SWIPS2 instrument.

Higher SWIPS2 frequency raises sensitivity to small particles (cross-section proportional to f4)

Both instruments equipped with electric heaters to minimize beam interruption by anchor ice  

2005-6 heater results: Mixed (SWIPS2 heater was turned off, SWIPS1 solved old problem but not another)

Self-Contained Deployment ConfigurationSelf-Contained Deployment Configuration

Early season results showed benefits of higher frequency … higher sensitivity to frazil by about 31 dB as predicted

235 KHz unit data- Low frequency results show weak returns from the water column (depths < 2.94m) .

Simultaneous 546 kHz data- High frequency results show full range of return variability in same intervals (depths < 4.8 m).

SWIP Water Level Data

Requires Atmospheric Pressure Data from Regional Weather StationRequires Atmospheric Pressure Data from Regional Weather Station

SWIPS-1001 BC Hydro- Converted to SWIPS5-3001

SWIPS-1002 BC Hydro- Converted to SWIPS5-3005

SWIPS5-3003 Makivik

SWIPS5-3004 University of Alberta

SWIPS5-3005 BC Hydro (Upgrade SWIPS1002)

SWIPS5-3006 University of Waterloo

SWIPS5-3007 Environment Canada

SWIPS5-3008 University of Alberta

SWIPS5-3009 Case Western Reserve Univ.

SWIPS5-3010 CERI Japan

3011 BC Hydro

3012Environment Canada National Water Research Institute

SWIP Customers