modellizzazione in mar ionio - agenda (indico)...e-mail: [email protected]...

Rosario Grammauta1, Salvatore Viola2,

(1) IAMC-CNR UO Granitola, Campobello di Mazara (TP), Italy,

(2) INFN - Laboratori Nazionali del Sud, Catania,,Italy

e-mail: [email protected]

Modellizzazione in Mar Ionio

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Summary

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Spatial distribution of the acoustic noise levels caused by shipping traffic in two areas of the

strait of Sicily.

Area of Capo Granitola

Summary

The first study area, the Gulf of Catania, isaffected by intense shipping traffic due to thepresence of three important harbors: touristic,commercial and military.

Calculation of the vessels’ position on a grid having mesh size 2000m x 2000m, with a time resolution of 30 minutes.

Study areaMin Longitude: 15.0°Max Longitude: 15.9°Min Latitude: 36.8°Max Latitude: 37.8°

Analyzed AIS dataTime period: November 2012 – November 2013 Number of vessels: 3621Total hour vessels: 43355

Cumulative minutes of ship traffic calculated in a 2000m x 2000m grid from AIS data

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0

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105

LAT

[deg

]

LON [deg]

Min

ute

Gulf ofCatania

Summary

The second area, instead, is the Area of

Capo Granitola where the massive

maritime traffic is attributable to the Strait

of Sicily.

Calculation of the vessels’ position on a grid having mesh size 2000m x 2000m, with a time resolution of 30 minutes.

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0

102

103

104

105

Min

ute

Cumulative minutes of ship traffic calculated in a 2000m x 2000m grid from AIS data

Study areaMin Longitude: 12.0°Max Longitude: 13.6°Min Latitude: 36.6°Max Latitude: 37.8°

Analyzed AIS dataTime period: November 2012 – November 2013 Number of vessels: 10329Total hour vessels: 156550

LAT

[deg

]

LON [deg]



Modelling underwater noise from AIS data

The acoustic noise induced by ship traffic in the Gulf of Catania has been estimated with afast custom-written MATLAB script from the data collected by the AIS receiver installed atthe INFN-LNS.

Script steps:

1. Calculation of the vessels’ position on a grid having mesh size 100m x 100m, with atime resolution of 10 minutes.

2. Estimation of the source spectral density for each vessel according to the ResearchAmbient Noise Directionality model RANDI 3.1 (depending on speed, length of thevessel).

3. Evaluation of the effects of the surface-dipole interference on radiated sound power.

4. Application of an easy geometric spreading model accounting spherical spreading tothe maximum water depth along the modeling radius, and cylindrical spreading forthe remainder of the radius .

5. Computation of the frequency-dependent absorption


• Calculation of the vessels’ position on a grid having mesh size 100m x 100m, with a time resolution of 10 minutes.

Study areaMin Longitude: 15°Max Longitude: 16°Min Latitude: 36.8°Max Latitude: 37.8°

Analyzed AIS dataTime period: 1st October, 2012 to 28th February, 2013

Cumulative minutes of ship traffic calculated in a 100m x 100m grid

Gulf of Capo Catania

Cu

mu

lative Min

ute

The pink triangle indicates the location of the

NEMO-SN1 observatory (37.5477 N, 15.3975 E, depth

2100 m).


• Estimation of the source spectral density for each vesselaccording to the Research Ambient Noise Directionalitymodel RANDI 3.1 (depending on speed, length of thevessel).

Breeding, J. E., Pflug, L. A., Bradley, M., Herbert, M., and Wooten, M. (1994). RANDI 3.1 User's Guide: Naval Research Laboratory.

Breeding, J. E., Pflug, L. A., Bradley, M., Walrod, M. H., and McBride, W. (1996). Research Ambient Noise Directionality (RANDI) 3.1

Physics Description: Planning System Incorporated.

In this formula, cV and cLare power-law coefficients for speed and length (taken to be 6and 2, respectively), v0 is the reference speed (12 kt), l0 is the reference length (300 ft),Ls0(f) is a mean reference spectrum, and g(f,l) is an additional length--‐dependentcorrection to the Ross model (Breeding et al., 1996).


• Evaluation of the effects of the surface-dipole interferenceon radiated sound power.

To account for the effect of surface-dipole interference on radiated sound power, sourcelevels at wavelengths greater than four times the source depth were attenuated accordingto the relation given by Brekhovskikh and Lysanov


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• Application of an easy geometric spreading modelaccounting spherical spreading to the maximum waterdepth along the modeling radius, and cylindrical spreadingfor the remainder of the radius .


• Computation of the frequency-dependent absorption

due to the relaxation of boric acid

B(OH3) and magnesium sulphate

MgSO4 molecules, and the shear &

bulk viscosity of pure water

TL = αR

Validation of Model

• NEMO-SN1 Observatory

• Long-term background noise measurements in the Gulf of Catania

• Evaluation of the background acoustic noise from ship traffic

• Comparison between the AIS-derived noise levels and the real acoustic data

The NEMO-SN1 Observatory and the Catania node of EMSO

Low frequency

hydrophone

INFN – LNS shore lab

NEMO – SN1

NEMO - SN1 is the first-established node of EMSO (European Multidisciplinary SeafloorObservatory), one of the incoming European large-scale research infrastructure includedsince 2006 in the Roadmap of the ESFRI (European Strategy Forum on ResearchInfrastructures). http://www.emso-eu.org/

NEMO-SN1 seafloor observatory has been operating from June, 2012 to May, 2013 in the Western Ionian Sea (East Sicily, 37°30’ N – 15°06’ E), at about 2100 m water depth.

Up: geographic location of the NEMO – SN1 multidisciplinary observatory

Right: NEMO – SN1 operative underwater

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http://www.emso-eu.org/

NEMO-SN1 low-frequency hydrophone

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Underwater acoustic noise in the Gulf of Catania was measured through a seismichydrophone, model SMID DT- 405D (10 Hz<f<1 KHz). Acoustic data were collected fromJune 2012 to May 2013, 24 hours per day, at a sampling frequency of 2 kHz, saved in 10min long files and stored at the INFN – LNS.

High Gain Channel (+60 dB)

Low Gain Channel (+30 dB)

Ch0=+60 dBCh1=+30 dB

DATA OUTDATA IN (CONTROL)

PPS – GPS (NMEA)

DIGITIZERPREAMP

About 4600010-min files stored

Distribution of the mean values of the PSD within each 10 min long recording (binning:1dB re 1 µPa2/Hz) for the whole NEMO-SN1 acoustic dataset (46040 recordings). PSD ofeach file computed using Welch's overlapped segment averaging estimator (window: 2048samples, overlap 50%). The gure also includes the curves of the 50th, 90th and 10thpercentiles of the mean values of the PSD calculated on the whole acoustic dataset.

Underwater background noise in the Gulf of Catania

46040 recordingsJune 2012 - May 2013

AIS data acquisition at the INFN-LNS laboratory

AIS data displayed in real time on a Google

map web page

INFN-LNS STORAGE

INFN – LNS CATANIA

The Automatic Identification System (AIS) is an automatic tracking system used by ships for identify and locate vessels. It gives information such as position, mmsi, speed and length.

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Comparison between AIS-derived and real acoustic data 1/3

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SPL within the 31.5 Hz, 63 Hz, 125 Hz and 250 Hz octave bands at the NEMO-SN1 location (redlines) was simulated with a time resolution of 10 minutes and it was compared with the SPLmeasured from NEMO-SN1 recordings (blue lines).A minimal background noise given by the smallest values of SPL obtained by the NEMO-SN1data was considered in the simulation. ___ NEMO-SN1 recordings

___ Simulation


Distribution of the difference (in dB) between the estimated SPL (dB re 1 µPa) at the NEMO-SN1 location and the SPL measured from NEMO-SN1 recordings (calculated with a time resolution of 10 min) for the 63 Hz and 125 Hz centered octave bands.

Period between 1st October, 2012 and the 28thFebruary, 2013.

Shipping noise evaluation at different depths

Estimated mean acoustic PSD at 100 Hz (dB re 1 µPa2/Hz) induced by the ship traffic in the study area for December 2012 at three different depths

Noise levels have been estimated at different frequencies and depths on a grid having meshsize 100m x 100m, with a time resolution of 10 minutes.

Mean PSD at 100 Hz Mean PSD at 100 Hz Mean PSD at 100 Hz

NEMO-SN1 NEMO-SN1 NEMO-SN1

Results

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Estimated mean acoustic PSD at 63 Hz (dB re 1 µPa2/Hz) induced by the ship traffic in the study area for all 2013 at 5m of depth.



Gulf of Catania

Results

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Estimated mean acoustic PSD at 125 Hz (dB re 1 µPa2/Hz) induced by the ship traffic in the study area for all 2013 at 5m of depth.



Gulf of Catania

Results

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Winter Spring Summer Autumn

dB

re

1 µ

Pa2

/Hz

Titolo asse

Comparison: Estimated, with Model, mean acoustic PSD at 63 Hz in the two areas of studio

Granitola 63 Hz Catania 63 Hz Mean 2013 Mean 2013

≈ 15 dB


Gulf of Catania

Application of Model

source spectral density for each vessel

the intensity of the source is dependent on the speed of the ship

we use the model to predict what would happenif the ships would change its speed

decreasing the speed of the ships also decreasesthe intensity of the signal emitted by ships

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dB

re

1 µ

Pa2

/Hz

Comparison mean acoustic PSD at 63 Hz Granitola (Year 2013)

Granitola 63 Hz 2013 Granitola 63 Hz reduced Mean 2013 reduced

Comparison acoustic PSD Granitola after changed speed ship

speed vesselsreduced by 10 %

≈ -3 dB



Comparison acoustic PSD Catania after changed speed ship

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dB

re

1 µ

Pa2

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Comparison mean acoustic PSD Catania (Year 2013).

Catania 63 Hz Mean 2013 Catania 63 Hz reduced Mean 2013 reduced

speed vesselsreduced by 10 %

≈ -3 dB

Gulf of Catania Gulf of Catania

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Management indication

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dB

re

1 µ

Pa2

/Hz

Estimated mean acoustic PSD at 63 Hz in the two areas for 2013

Granitola 63 Hz Catania 63 Hz Mean 2013 Mean 2013 marine strategy

Gulf of Catania

Marine Strategy

≈12 dB



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Hypothesized mean acoustic PSD at 63 Hz in the two areas for 2013

marine strategy Granitola 63 Hz Mean 2013 Catania 63 Hz Mean 2013


≈ 8 dB

the speed of the ships is decreased by 10 %

Gulf of Catania

Marine Strategy


If speed vesselsreduced by 10 %Area of

Capo GranitolaArea of

Capo Granitola

If speed

vessels

reduced by 20 %


Area in the threshold of the Marine Strategy

(dB re 1 µPa2/Hz)

Conclusion and Future

• The model is a useful tool to evaluate the spatial distributions of

induced noise from vessel traffic. It is able to generate real-timemaps of noise using exclusively of AIS data;

• The model can be a useful tool for marine traffic control and for

establish new mitigation rules in order to reduce the marine

noise (Europea Marine Strategy).

• Improve the model in shallow water

• Improve the model by adding information about the tonnage and

draft of the ships;

• Improve the validation of the model increasing the data

collection point (Artic, Antartic, etc).

FUTURE

CONCLUSION

NOISE MAP PROJECT

Thanks for yourattention

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Suitability of five commonly used propagation models for different water depths and frequencies

modellizzazione in mar ionio - agenda (indico)...e-mail: [email protected]...

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