Distribution format

• GeoTIFF

  (

  1.1

  )

• CSV

  (

  inapplicable

  )

• XML

  (

  1.0

  )

OnLine resource

Shom geoportal  

Shom geoportal

OnLine resource

DCSMM_D11_C21_2012_3857_WMSR  

Access point / WMS raster

OnLine resource

Download service  

Hierarchy level

Series

Statement

The criteria D11C2 is evaluated by the mean quadratic pressure. The metric used is the value of the maximum sound level over a calendar year in the two third-octave bands centered on 63 Hz and 125 Hz respectively, expressed as sound levels expressed in dB re 1 µPa² with a spatial resolution of 1 minute of degree. These sound levels are inferred using a digital model, validated locally by in situ measurements. The data used are two types: - in situ noise data: the collection of this data come from of the MAMBO device (Acoustic Monitoring and Measurement by Noise of Opportunity). The system is based on a perennial network of measurement stations and the collection of opportunity data (incidence measurements, technological experiments, oceanographic monitoring, etc.) - maritime traffic data, mainly in its trade and transport component, collected by Lloyd’s for declarative port-to-port movements. The data subject to regulatory monitoring by Automatic Identification System (AIS) on land from the DAM (Direction des Affaires Maritimes) and provided by Cerema are supplemented by satellite and land data from Lloyd’s. The parameter evaluated in the indicator is the level of ambient traffic noise expressed in dB re 1 µPa². The calculation of the acoustic levels is carried out by integrating the levels on two frequency bands; the first centered on 63 Hz (from 56 Hz to 71 Hz, called the 1/3 octave band at 63 Hz) and the second on a frequency band centered on 125 Hz (from 112 Hz to 141 Hz, called the 1/3 octave at 125 Hz). The methodology for calculating this indicator is based on the joint use of in situ data (measurements on hydrophones) and digital models of noise generated by maritime traffic. For this assessment, the sound levels are calculated by modeling the monthly traffic noise, for the representative months of the four seasons (January, May, August and November) and for the depths of 5, 20, 30, 50, 80, 150 and 300 m (except for the English Channel - North Sea marine sub-region: 5, 20, 30, 50 and 80 m). The metric used is the annual maximum per cell for the months of calculation considered. To facilitate interpretation, we are interested in the distribution of maximum sound levels in the meshes of the MSR at percentiles 5, 25, 50, 75 and 95. The lack of in situ measurements does not allow the indicator to be evaluated. from real data. Otherwise, digital modeling is used and the results are validated locally by comparison with in-situ measurements. The model used is a statistical traffic noise model (CABAT, Calculation of Ambient Traffic Noise) used at Shom since 2006. The Good Ecological Status is qualitatively assessed taking into account the indicator, the level in the frequency band of 1/3 of an octave, specificities of the physics of acoustic propagation in each sub-region, and additional knowledge on maritime traffic monitoring. Three pressure levels are then defined: strong, moderate and low. These pressure levels are evaluated based on the magnitude of the trend relative to the uncertainty and its spatial distribution. The uncertainty in the model is at least 4 dB re 1 µPa², this is the basis for judging a significant increase or not. Moreover, one considers the spatial distribution of the interannual difference and one defines an acceptable threshold of 50% of the meshes for which there is a non-significant increase.

gmd:MD_Metadata

File identifier

DCSMM_D11_C21_2012.xml   XML

Metadata language

French

Character set

UTF8

Hierarchy level

Series

Hierarchy level name

Produit

Date stamp

2021-10-07T11:24:22

Metadata standard name

ISO 19115:2003/19139

Metadata standard version

1.0