Synthetic Aperture Radar (SAR) Data Hydrocarbon Migration and Seepage in the Timor Sea and Browse Basin. An Integrated SAR and Geological Study GIS.

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.

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Dataset citation

ANZLIC unique identifier: ANZCW0703003247

Title: Synthetic Aperture Radar (SAR) Data Hydrocarbon Migration and Seepage in the Timor Sea and Browse Basin. An Integrated SAR and Geological Study GIS.

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Custodian

Custodian: Geoscience Australia

Jurisdiction: Australia

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Description

Abstract:

This is the interpretation of satellite imagery or SAR data, showing the location of natural

and non-natural 'slicks/seeps' along the surface of the ocean. These shapefiles show the position of the slicks along the the top of the sea. There are polygons and general point locations of the slicks.

The vector data is: sar_scene_boundaries.shp

sar_seeps_poly.shp

sar_seeps_point.shp

There are also some of the actual scenes themselves. These 5 degraded BIL images are used as examples of prime targets used for locating natural seeps. These are located in "/timor_gis/grids/radarsat_grids/" on the CDROM.

The raster files are: c0009642.bil

c0012251.bil

c0013611.bil

m0163580.bil

m0163581.bil

ANZLIC search words:

MARINE Exploration
PHOTOGRAPHY AND IMAGERY Satellite
POLLUTION Water Monitoring
WATER Hydrochemistry Classification

Spatial domain:

locality map

Geographic extent name: AUSTRALIA INCLUDING EXTERNAL TERRITORIES - AUSAAT - Australia - Australia

Geographic extent polygon: 121 -8.7, 127.5 -8.7, 127.5 -17, 121 -17, 121 -8.7,

Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register

Geographic bounding box:: North bounding latitude: -8.7 °; South bounding latitude: -17 °; East bounding longitude: 127.5 °; West bounding longitude: 121 °

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Data currency

Beginning date: 2000-07-01

Ending date: 2000-11-05

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Dataset status

Progress: Complete

Maintenance and update frequency: Not Known

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Access

Stored data format:: DIGITAL - bil Band interleaved by line (BIL) image Geographic WGS84; DIGITAL - shp ArcView shape file ArcView Geographic WGS84

Available format type:: DIGITAL - shp ArcView shape file ArcView Geographic WGS84

Access constraints:

Licence required.

Free Data Download

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Data quality

Lineage:

All the vector SAR data was origional done by a contractor (Nigel Press & Associates - NPA) using the SAR scenes original obtained by AGSO and are the subject of this metadata. AGSO received the raw data/interpretation in EXCEL format. This was then loaded into ARCVIEW. No extra work was needed.

The interpretation of both polygon and points have overlapping areas. This is due to the fact that the interpretation was done to multiple scenes over the same areas. This is to show the changes over time, if any.

The interpretation that was done using the 5 raster images can be overlayed over these images, showing a consistency throughout the whole area.

The raster data (SAR Images) was orginally obtained by AGSO through AUSLIG and then imported into ERMAPPER. The images were then degraded (for licence agreement issues) and captured as raster BIL files. Once the header data was made the images were then loaded straight into ARCVIEW.

Positional accuracy:

Vector Data - No analysis of the positional accuracy of any of the vector features has been undertaken, however due to the accuracy of the interpretation it can be considered that all vector features are within 30 metres of their true position.

Raster Data - With the degrading of the raster images from 12.5m to 50m cell size and the georeferencing of the images a positional accuracy can be 'estimated' within 100m.

Attribute accuracy:

Regarding the vector data the attributes are for naming purposes only. For the actual interpretation an attribute of "Category" has been placed. This is the actual 'group' of what category each slick falls under. This naming of each slick/seep was up to the interpreter and is therefore not prone to any error.

The "Category" attributes or confidence levels are classified below:

Secondary Class: Confidence level of '2'. With '1' being the extremely confidant (usually by visual sighting out in the field). Small, almost all less than 1km long, usually linear but also often "blobby" with distinct edge. Thin, moderate to low ocean-slick backscatter contrast, responding to current and so often "crossing" swell or wave fronts.

Third Class: Confidence level of '3'. Usually tiny, as small as 120m long and indistinct. Thin slicks are inferred but it is not possible to measure the backscatter contrast. Their significance is often only determined by their geological context established by screening their pattern of distribution to seismic data.

Individual Natural Film: Natural film slicks (NFS) are widespread over 100s to 1000s of km and occur in groups, often adjacent to calm areas. This is because they form strictly in response to declining wind and are not related to petroleum. They have a filamentous disposition, often eddying and shaped by swell, internal waves and upwelling. They respond predominantly to current and wind-envelopes.

Pollution:Where fresh, pollution slicks are unequivocally categorised. They usually have a strong contextual relation to the source of pollution: ships, ship wakes, shipping lanes, port facilities, oil rigs, coastal factories and estuaries.

Remanant Pollution: Emulsified oil and tar fragments and the resulting small slicks usually retain a contextual relationship (3 to 10 days) to the source of pollution or to larger slicks. Where the context is missing the pollution origin is less clear.

The raster data has no attributes.

Logical Consistency:

All vector and raster data has been visually checked for extraneous points and value added data.

polygons have been checked for closure and dangles.

Completeness:

All vector and raster data and details are complete and verified.

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