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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.
