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Mid-FrequencyAmbientNoiseExperiment–4-21August2018ObjectiveObservationsofthedeep-watermid-frequencyambientnoisespatialstructureandtemporalfluctuationcharacteristics.BackgroundThe2Dmid-frequencyacousticarrayconsistsof512hydrophoneelementsarrangedas8verticalstavesof64-elementseach(Fig.1).Whilethedataacquisitionsystemisself-contained,the512-element2Darraywillbedeployedto~150mdepthandsubsequentlytetheredtoasurfacebuoyviaanumbilicalcablethatprovidescontrolandremotedataaccess(Fig.2).ThephysicalconfigurationofthearrayisshowninFigs.3-4.Theumbilicalcableisstoredonawinch(Fig.5).Theoffboardbuoy(Fig.6)includesbothGPSpositioningandseveralcommunicationoptionsincluding900MHz,2.4GHz(802.11),andIridium.ApproachWewillcarryoutadeep-watermid-frequencyambientnoiseexperimentwitha2Dacousticarrayovertheperiod4-21August2018.ThedeploymentlocationisshowninFig.8andis~300nmENEofIcelandin~3600mdeepwater.InadditiontoobservationsoftheMFambientnoise,low-levelsourcetransmissions(lessthan160dBreμPa)inthe1-9kHzbandalsowillbecarriedoutintheimmediatevicinityofthearrayforinsitucalibrationpurposesandatlong-range(1,2,and3convergencezonesor~30nm,~60nmand~90nm).EnvironmentalmeasurementswillincludetakingtwoCTDsperdaytoadepthof~1000m.AdditionalXBTmeasurementswillbemadeasneeded.Inaddition,wewilldeploya~500maperture,freely-drifting,self-recordingthermistorstringafewkilometersfromthearray(Fig.7).Location66°45’N,01°30’Wor~300nmENEofIceland.Waterdepthis~3600m(Fig.8).

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Schedule Date/Time 01-03Aug18 0800L LoadMPLhardware. 04Aug18 0800L DepartReykjavik,Iceland. 07Aug18 0800L Arriveexperimentlocation(~300nmENEofIceland).

Carryoutatleast2CTDcastsperday. Note:Daysonsite–11 Deploythermistorstring(2hrs).Prepareacousticarrayfordeployment. 08Aug18 Deployacousticarray(3hrs). Acousticsourcetransmissionsinimmediatevicinityofthearrayfor

calibrationpurposes. 09-11Aug18 (1)Acousticsourcetransmissionsinimmediatevicinityofthearrayfor

calibrationpurposes.(2)Acousticsourcetransmissionsatlongrange(~30nm,~60nm,and~90nmfromarray).

12Aug18 Recoveracousticarray(3hrs).Rebattery,downloaddata,preparefor

redeployment. 13Aug18 Deployacousticarray(3hrs). Acousticsourcetransmissionsinimmediatevicinityofthearrayfor

calibrationpurposes. 14-16Aug18 (1)Acousticsourcetransmissionsinimmediatevicinityofthearrayfor

calibrationpurposes.

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(2)Acousticsourcetransmissionsatlongrange(~30nm,~60nm,and~90nmfromarray).

17Aug18 Recoveracousticarray(3hrs)andthermistorstring(2hrs). 18Aug18 0900L Departexperimentlocation. 21Aug18 0800L ArriveReykjavik,Iceland.Beginoffloadingship. 22-23Aug18 0800L OffloadMPLhardware.

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Figure1.Deploymentconfigurationofthe512-elementmid-frequencyarrayarrangedina2-Ddistributionofelements(8verticalstavesof64-elementseach).

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Figure2.Deploymentconfigurationofthe512-element2Dmid-frequencyarraywithsurfacebuoy.

LIFT LOOP(2m)

18m SURFACERECOVERY LINE

7 38# SPHERESSPACED @ 2m

5-6 SUBMERGED

4 X 125# ELLIPSOID FLOATS

150m UMBILICAL

4 X 195# ELLIPSOID FLOATS

MARKER FLOAT WITH:IRIDIUM BEACON, RADIO BEACON,FLASHER, RADAR REFLECTOR

512 ELEMENT MF NOISE ARRAY DEPLOYMENTCOMM BUOY: - 900 MHZ, 2.4GHZ RADIO MODEMS - IRIDIUM X1202 MODEM - GPS - FLASHER, RADAR REFLECTOR - IRIDIUM BEACON XMI 11k - 3 ALKALINE BATTERY PACKS - AIS TRANSPONDER

6/19/17

MR5000B ELECTRIC RELEASEANCHOR425# AIR

~360# WATER

DRAWING NOT TO SCALE

~150m

14m (SEE DETAIL DRAWING)

BOTTOM STRUCTURE

ARRAY - 512 HYDROPHONES @ 0.125m SPACING (CENTER) - 2 STRENGTH MEMBERS (L,R) - LIFT LOOPS @ 2m SPACING

TOP STRUCTURE WITHRECORDING ELECTRONICS

AND LITHIUM BATTERY PACKS

BUNDLED ARRAY CABLES

1400#

620#

2.5m

REAL TIME TILT/DEPTH

700#

130#

100#

UMBILICAL (4TSP)

245#

MARKER FLOAT WITH:IRIDIUM BEACON, RADIO BEACON,FLASHER, RADAR REFLECTOR

4 90#TAYLORFLOATS

2 90#TAYLORFLOATS

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Figure3.Physicalconfigurationofthe512-elementmid-frequencyarrayarrangedina2Ddistributionofelements(8verticalstavesof64-elementseach).Dataacquisitionelectronicsandbatterypressurecasesontop.

Figure4.Cartforpositioningofthe2Dmid-frequencyarrayondeckpriortodeployment.

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Figure5.Winchfordeploying2Dmid-frequencyarrayumbilicalcable.

Figure6.SurfacebuoywithGPS,900MHz,2.4GHz(802.11),andIridiumantennas.

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Figure7.Freely-drifting,self-recordingthermistorstring.

500m

~4m

MFN4 DRIFTING THERMISTOR STRING

DUAL ACOUSTIC RELEASE

6/19/17

T-LOGGERS (SEE CHART)

500m 5/16" ULTREX

2 58# HARDBALL FLOATS

200# WEIGHT

3 38# SPHERES

COMM BUOY: - 900 MHZ, 2.4GHZ RADIO MODEMS - IRIDIUM X1202 MODEM - GPS - FLASHER, RADAR REFLECTOR - IRIDIUM BEACON XMI 11k - 3 ALKALINE BATTERY PACKS - AIS TRANSPONDER

4 10' STRAPS

2 90# TAYLOR FLOATS

THERMISTOR STRINGSENSORS DEPTH (m)

DST-TILT (800) 2.5 250 497HOBO U12-015 2.5 5 7.5 10 12.5 15 17.5

20 22.5 25 27.5 30 32.5 3537.5 40 42.5 45 47.5 50 5560 65 70 75 80 85 9095 100 110 120 130 140 150

160 170 180 190 200 225 250275 300 350 400 450 497

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Figure8.Locationofmid-frequencyambientnoiseexperimentininternationalwaters~300nmENEofIcelandin~3600mdeepwater(66°45’N,01°30’W).Sourceoperationswillbewithina~100nmradiuscirclecenteredonarray.Thepinsoutsidethecirclemarktheinternationalwatersboundary.