O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

Case Study 1

ASAR Wide Swath Mode Image

30 July, 2004

ASA_WSM_1PNTSS20040730_200821_000000612029_00057_12636_0000.N1

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

© 2007, Andrey G. Kostianoy

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Case study N1

ASAR ENVISAT image of the southeastern Baltic Sea on 30 July 2004, 20:08 GMT.

We observe:(1) a chain of oil spills in the Gulf of Gdansk; (2) is an unclear patch of unknown nature.

Questions:1. Why does the spill form a chain shaped as seen in (1) ?2. What is the direction of oil propagation?3. What is the patch seen in (2)?4. Why (2) has a round form?

It is not possible to answer these questions based only on the SAR image. Ancillary satellite and meteo information is required. Fig. 1

Satellite Orbit Track Frame Date TimeEW 12636 57 1116 20040730 20:08:05Resolution - 75 m/pixel

ESA 2004Distributed by Kongsberg Satellite Station

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Wind speed (m/s) measured by satellites QuikSCAT, Jason-1 and at meteo stations in ports on 30 July 2004 18:00 - 24:00 GMT

2-3 m/s in the area of the spill

Fig. 5

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O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

© 2007, Andrey G. Kostianoy

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The Baltic SeaCase study N1

ASAR ENVISAT image of the southeastern Baltic Sea on 30 July 2004, 20:08 GMT.

Wind speed 2-3 m/sWave height 0.6-1m

We observe:(1) a chain of oil spills in the Gulf of Gdansk; (2) is an unclear patch of unknown nature.

Questions:1. Why does the spill form a chain shaped as seen in (1) ?2. What is the direction of oil propagation?3. What is the patch seen in (2)?4. Why (2) has a round form?

It is not possible to answer these questions based only on the SAR image. Ancillary satellite and meteo information is required.

Fig. 1Satellite Orbit Track Frame Date TimeEW 12636 57 1116 20040730 20:08:05Resolution - 75 m/pixel

ESA 2004Distributed by Kongsberg Satellite Station

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

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Unfiltered Filtered Threshold 2100

Threshold 2400

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

1962 pixels

3165 pixelsArea:0.75*0.75*3165 ≈ 17.8 km2

Area:0.75*0.75*1962 ≈ 11 km2

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

© 2007, Andrey G. Kostianoy

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The Baltic SeaCase study N1

ASAR ENVISAT image of the southeastern Baltic Sea on 30 July 2004, 20:08 GMT.

We observe:(1) a chain of oil spills in the Gulf of Gdansk; (2) is an unclear patch of unknown nature.

Questions:1. Why does the spill form a chain shaped as seen in (1) ?2. What is the direction of oil propagation?3. What is the patch seen in (2)?4. Why (2) has a round form?

It is not possible to answer these questions based only on the SAR image. Ancillary satellite and meteo information is required.

Fig. 1Satellite Orbit Track Frame Date TimeEW 12636 57 1116 20040730 20:08:05Resolution - 75 m/pixel

ESA 2004Distributed by Kongsberg Satellite Station

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

Mesoscale water dynamics in the Gulf of Gdansk was revealed by MODIS-Terra (250 m resolution) on 30 July 2004, 09:40 GMT, i.e. 10.5 hours before ASAR.

Superposition of MODIS image and oil spills from ASAR images showed that:

1. The elongated form of the oil spill in (1) is due to a vortex dipole composed of a cyclone-anticyclone pair.2. The oil-spill chain is involved in the anticyclonic rotation of the dipole, and will move westward 3. The round feature in (2) is the center of the cyclonic part of the dipole.4. The feature is round because of a spiral rotation of water directed to the center of this cyclonic eddy.

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Vortical dipole structure also revealed in data from MODIS Aqua and AVHRR

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The MODIS Aqua image obtained about 8.5 hours before confirms the westward drift of the spill

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Case study N1 SummaryA series of dark patches in the ASAR image is identified as an oil spill (1).

The round feature in (2) is found the center of an intensive cyclone of the dipole. Debris is likely to accumulate in its centre, including possible remains of oil products, wood, plastic bottles, etc.

The ASAR image also shows an oil platform and three ships northwestward of it without signatures of oil pollution.

The drift of the observed oil spill will depend on the intensity of the anticyclone, the motion of the dipole itself, which in the period between 28 and 30 July turned in the anticyclonic direction (clock-wise) to the south on 90o, and on wind speed / direction.

Unfortunately we could not follow the fate of the spills, because the next ASAR image over the Gulf of Gdansk was acquired only on 2 August (20:14 GMT). The image was free of the oil spills that can be explained by strong mixing during the day of 2 August when the wind reinforced up to 8-10 m/s. These days the Gulf was covered by clouds that did not allow receiving the IR and optical images from NOAA and MODIS, and trace the variations in the mesoscale dynamics.

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Combination with numerical modellingForecast of the oil drift was made by an interactive numerical model Seatrack Web (Ambjörn, 2004). This version of a numerical model on the Internet platform has been developed at SMHI (The Swedish Meteorological and Hydrological Institute) in close co-operation with Danish authorities. The system is based on an operational weather model Hirlam (High Resoluted Limited Area Model, 22 km grid) and circulation model Hiromb (HIgh Resolution Operational Model for the Baltic Sea, 24 layers), which calculates the current field at 1 n.m. grid.

The model can forecast the oil drift for two days ahead or make a hind cast (backward calculation) for 10 days in the whole of the Baltic Sea. When calculating the oil drift, wind and current forecasts are taken from the operational models. An oil spreading calculation is added to the currents, as well as oil evaporation, emulsification, sinking, stranding and dispersion.

This powerful system today is in operational use in Sweden, Denmark, Finland, Poland, Estonia, Latvia, Lithuania and Russia (Ambjörn, 2004).

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The forecast (Fig.7) showed that during two days the chain of oil spills will move southward in accordance with the wind and current fields, and will partially reach the Vistula Spit. The discrepancy with observations in the ASAR and MODIS data is explained by the fact that the numerical model does not always resolve meso- and small-scale dynamical features like eddies, dipoles, jets, filaments, meanders, etc.

The MODIS and ASAR data shows that the oil spills drift goes almost along the streamlines of an anticyclonic vortex. A little shift is explained by 10.5 hours lag between MODIS image (morning) and ASAR ENVISAT (evening), on which oil spills have been detected.

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

Case Study 2

ASAR Wide Swath Mode Image

11 August, 2004

ASA_WSM_1PNTSS20040811_090614_000000612029_00222_12801_0000.N1

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

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1930’E 20E 2030’E 21E

1930’E 20E 2030’E 21E

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ESA 2004Distributed by Kongsberg Satellite Station

Case study N2ASAR ENVISAT image of the southeastern Baltic Sea on 11 August 2004, 09:06 GMT.

We observe:1 – D-6 oil platform2 – weathered oil spill (1915E, 5527N)3 – weathered oil spill (1912E, 5438N)4 - zone of no wind5 - wind shadow6 - surface-active substance 7 - surface-active substance

Fig. 8Satellite Orbit Track Frame Date TimeEW 12801 222 2484 20040811 09:06:01Resolution - 75 m/pixel

Basing only on this ASAR image it is not possible to interpret correctly all phenomena. Ancillary satellite and meteo information is required.

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Wind speed (m/s) measured by satellite QuikSCAT on 11 August 2004 on 02:59-04:41 and 16:45-18:28 GMT

Note: correspondence of low wind area right with a calm zone (4) in ASAR image.

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O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

AVHRR IR and MODIS-Terra optical characteristics of the sea surfaceNote: upwelling areas along the coast (band of cold water in blue color), a warm area (yellow color) which corresponds to the calm zone in ASAR image, and a complicatedwater dynamics in the Gulf of Gdansk and offshore the coasts related to the upwelling

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Oil spill (3) was combined with MODIS image received 1 hour after ASAR. The Location of the oil spill inside a compact structure of two dipoles shows that it will be transported along a periphery of a large anticyclonic eddy northwestward. Light colors show high concentration of suspended matter resulted from the Vistula River runoff in the southern part of the Gulf and from the Kaliningrad Bay (red arrows). Suspended matter is also entrained in the vortical motion and highlights very well peculiarities of small-scale water dynamics in the Gulf of Gdansk.

O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A O I L S P I L L M O N I T O R I N G I N T H E S O U T H E A S T E R N B A L T I C S E A

Numerical modelling of the oil spill (3) drift and transformation (Seatrack Web, SMHI), detected on 11 August 2004 on 9:06 GMT, showed that under forecasted wind and currents the spill will drift westward and then northwestward along the Hel Peninsula till 14 August if wind and currents will not change sharply. In this case the model results corresponded well to the forecast made on the base of satellite imagery.