Sediment Sediment below icebelow ice

TemperatureTemperaturesensorssensors

qq = - = -kk dTdT//dzdz

kk = thermal conductivity = thermal conductivity

dTdT//dzdz = thermal gradient = thermal gradient

Te

mp

era

ture

Te

mp

era

ture

TimeTime

each sensor...each sensor...

Heat flowHeat flow, q (mW/m, q (mW/m22))

Bottom Bottom waterwater

Pen

etra

tion

Pen

etra

tion

Partial Partial equilibrationequilibration

ProbeProbeextractionextraction

WISSARDWISSARDheat flowheat flow probe probe

Weight standWeight stand

LanceLance

MasterMastermachinistmachinist

Key features:Key features:• • Stainless steel construction Stainless steel construction

(except for two brass rings)(except for two brass rings)• • Max. diameter = 25 cmMax. diameter = 25 cm• • Length, ~2.5–3 m Length, ~2.5–3 m (2 or 3 sensors on lance)(2 or 3 sensors on lance)• • Adjustable weight, ~200-450 kgAdjustable weight, ~200-450 kg• • Autonomous outrigger probesAutonomous outrigger probes• • Bottom water and tilt sensorsBottom water and tilt sensors• • Shipping crate with integrated Shipping crate with integrated

cradle for servicing, launch, cradle for servicing, launch, recoveryrecovery

Weight stand featuresWeight stand features

Stabilizing ringStabilizing ring(holds lance)(holds lance)

Tapered Tapered upsetupset

6 U-channels6 U-channels(hold weights)(hold weights)

FrontFront

RearRear

Tapered Tapered upsetupset

WeightWeightclampclamp

Oceanographic-grade swivelOceanographic-grade swivel

Limited travel on pinLimited travel on pin

7 klb strength7 klb strengthNo greaseNo grease

Outrigger mountOutrigger mount

Autonomous outrigger probesAutonomous outrigger probes

Deck boxDeck box(program, download)(program, download)

Clamshell protects loggerClamshell protects logger

Bolted on lanceBolted on lance

Electronics and batteryElectronics and battery

Pressure casePressure case

Short tip version (for bottom water)Short tip version (for bottom water)

16-bit A/D16-bit A/D1 mK resolution1 mK resolutionCalibrated (NIST-traceable) to ± 2 mKCalibrated (NIST-traceable) to ± 2 mKThrough-case serial Through-case serial

communicationcommunication

Thermistor in long probeThermistor in long probeDelrin outriggerDelrin outrigger

Thermal conductivity system, data processingThermal conductivity system, data processingThermal conductivityThermal conductivity• • Needle probe methodNeedle probe method• • Constant heatingConstant heating• • Custom software for Custom software for

acquisition and processingacquisition and processing

Heat flow processingHeat flow processing• • Extrapolation of 6-7 minutes of Extrapolation of 6-7 minutes of

subsurface datasubsurface data• • Multiple probes --> gradientMultiple probes --> gradient• • Combine with thermal Combine with thermal

conductivity --> heat flowconductivity --> heat flow• • Monte Carlo analysis of Monte Carlo analysis of

uncertaintiesuncertainties