NILU scientists have built and tested new ultra-violet imaging camera that can detact emissions of SO2 and provide quantitative estimate of SO2 flux. The test was carried out in Ny-Ålesund where many large cruise ships emit unknown amounts of SO2 into the "pristine" air. The work was funded by Arctic Field Grant.

During the summer months in Svalbard many cruise ships enter the harbours at Longyearbyen and Ny Alesund and travel around the coastal regions. Emissions from these ships contain SOz and contribute gaseous pollutants to the atmosphere. The exact amount, frequency and fate of these emissions are very poorly understood and any environmental protection, if necessary, will require data and measurements to quantify the problem. This innovative pilot study has made estimates of the SOz emissions from cruise ships and has provided (for the first time) rapid scanning images of the behaviour of these emissions on short time-scales.

The NILU ultra-violet imaging camera (EnviCam) is a scientific instrument for use in identifying and measuring polluting gases in the troposphere. The camera consists of a highly sensitive CCD array (1344 x 1024 pixels). The quantum efficiency (QE) of the CCD is quite high from 280-320 nm. A highly transmissive UV filter in front of the lens excludes all light beyond 320 nm, thereby isolating the S02 gas. The camera is able to image S02 plumes from distances up to 10 km and can quantify the abundance as well as map fluxes. The NILU UV camera was mounted at various locations around Ny-Ålesund to optimise viewing geometry and to test the ability of the camera to view ship emissions from different distances. Generally, it was found that the camera worked very well at distances of 1-2 km from shore. Too close and the restricted field of view of the camera made it difficult to acquire continuous ship effluent. Too far away and the increasing path length between camera and target causes a reduced signal.

The camera can acquire images at user selected intervals and varying exposures and rates. Generally, sequences of several minutes to 10's of minutes were made while a cruise ship was steaming n or out of the fjord, Since the light was good, measurements could, in principle, be-made throughout the full 24 hours of the day, However, on several days, low cloud, fog and slight precipitation caused loss of data. On the day when the largest cruise ship entered Kongsfjorden (MS Costa Magica), the conditions were perfect and excellent data were acquired, Most of the data are in the form of image sequences and are still being analysed. Some measurements were also made of the Ny Alesllnd power plant, although this appeared to be emitting at a very low rate.

It is worth mentioning that the amount of SO2 emission from the cruise ship is not directly related to the size of the ship. In several cases the smaller ships had a similar range of emissions as the large cruise liners (e.g. MS Expedition - 120 passengers, 6336 gross tonnage, 11-14 gs-1 emissions vs. MS Costa Magica - 3470 passengers, 102587 gross tonnage, 10-18 gs-1 vs. MS Columbus 423 passengers, 15000 gross tonnage, 15 gs-1).

The SUVEX campaign proved to be highly successful: the main goals of the
experiment were achieved, including demonstrating the utility of a UV camera to
measure ship emissions, the ability to make rapid movie sequences of emissions
and to quantify these in terms of emission rates (in gS·l). In the future the autonomous use of the camera during the summer season will be possible, providing S02 webcam data to a webinterface for all stakeholders to access directly. At a later date it would be useful also to test the NILU infrared CyClops camera as this can also measure S02 and could be used in very low light conditions (e.g. polar night).

Source & contact: Fred Prata, NILU (fred.prata@nilu.no) and Are Båcklund, NILU.

This is Fred Prata's report to SSF, Arctic Field Grant 2009 (AFG2009 ID443; RiS ID 3331)

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Ultra-violet image of MS Mona Lisa anchored in Ny-Ålesund.

MS Costa Magica on ultra-violet image (C) and on visible camera image (D).

Ny-Ålesund power plant emissions on the ultra-violet image (all images: Fred Prata, NILU)