SATELLITE APPLICATIONS WORKSHOP

Chair: Merv Lynch
Rapporteur: Doug Edsall

The Workshop Chairman, Merv Lynch, made a presentation on "Indian Ocean Satellite Applications and Remote-Sensing Capacity-Building."

What does IOGOOS require. First, it is not always possible to remotely sense some parameters some of the time. Among those that are not feasible at all are water nutrients and salinity.

Regarding parameters that can be remotely sensed most of the time, the most useful in the IOGOOS context are: surface currents and ocean color/chlorophyll concentration, including seasonal cycles. Ocean features that are of special interest are cyclone-induced upwelling, primary production, and ocean eddies, although the latter tend to stay put and spin. Satellite remote sensing, at present, can only reveal certain ocean characteristics to a depth of 30 m, at most. About a dozen satellites covering the Indian Ocean are now operating.

Regarding the application of satellite remote sensing in the region, it appears necessary to stimulate regional interest and to identify problems whose solution would be facilitated by satellite remote sensing, and to set priorities. As a first step, it would be useful to construct inventories of experts, of interests, and of existing infrastructure. Training workshops and demonstration pilot projects would help in this sense.

The likely problems lie predominantly in the data acquisition, management, and archiving, in the exploitation of the data and the development of useful data products. Data or data products on some phenomena fires, floods, severe weather conditions, oil spills, for example can be made available in real time; but certain kinds of data may be in delayed time, by Internet, for instance, although bandwidth competition on the Net is possible. There is also the problem of integrating the information due to differences in satellite overpass times, in data formats, and data gridding. The volume of data is also enormous, so it is necessary to extract a meaningful message from the data. But this is only the beginning of this problem: the volume will grow rapidly from hundreds of gigabytes, today, to hundreds of terabytes, tomorrow, requiring PCs with speeds of 250 gigaherz to process them.

It is also necessary to decide which possible products are appropriate; for this, it is necessary to know precisely what the problems are. That of fishery management, especially in shallow water, is a common one. And the assimilation of data into models is another; but the question is: which models?

There are still some credibility gaps with respect to satellite remote sensing; and capabilities vary from nation to nation. So capacity-building and training are needed, preceded, however, by an assessment of training facilities.

Four speakers then gave presentations.

Frank Shillington presented a paper on "Remote Sensing in the South-Western Indian Ocean".

The majority of the relevant data come from the SeaWiFS and are held at NASA. These data show that chlorophyll is a better signal for ocean structure than is temperature, but care is needed in choosing the colour palette for the images. Nevertheless, a long-term climatology from archive data is feasible. It has proven useful to produce a trace from the coast out to the chlorophyll 1 mg/m3 contour as an indicator of coastal primary productivity. The LME (Large Marine Ecosystem) project in the region could channel relevant data/products to IOGOOS.

Shailesh Nayak presented a paper on "Satellite Ocean-colour Applications: a Case Study in the North Indian Ocean".

SeaWiFS and OCM satellites carry ocean-color scanners; the main problem is to remove the signal returned from the top of the atmosphere (about 90%) and use the remaining 10%. Then there is the need to integrate the sea-surface temperature data with the chlorophyll data. Validation experiments show a reliability (of the prediction) of 70 to 90%. This has, nevertheless, led to 70 to 200% increases in fish catches, although the pelagic fisheries benefit more than the demersal trawl fisheries from the ocean-color data. Predictions generally remain valid for about five days, so there is a need to extend this validity period.

Although the coral reefs and mangroves are being monitored, it is not easy to show changes in mangrove species composition. Coral bleaching can be detected because the reef flat is usually taken over by macroscopic algae. Sediment dynamics, coastal erosion and the tidal front are detectable, as is coastal-zone pollution to some degree, insofar as it can be associated with the sediment dynamics. Coastal-zone flooding and cyclone damage are detectable. Harmful algal blooms are detectable by the infra-red response at the sea surface. Water clarity (measured by the diffuse attenuation and reflection of downwelling irradiance) is an important parameter with respect to tunas and to photosynthesis.

It is clearly very important to ensure that the data products are useful and made available at the right levels: societal, national, and of international organizations.

Nassar Zaker presented a paper on the "Application of Satellite Oceanography in the Persian Gulf—and the Current Status".

Present capabilities cover: coastal-zone and oceanic applications up to the regional level; and hazard assessment—storm surges, oil spills, flooding, habitat mapping. Iran's satellite remote sensing capabilities are limited; at present it receives data from NOAA. In the region, such capabilities are limited to Oman, and there are satellite-receiving facilities in Kuwait.

The priorities for Iran are habitat, pollution, and coastal-zone mapping, and the needs are for increasing public awareness, capacity-building, data and information exchange within the region and with the outside world. There is a low level of expertise; fisheries still do not make use of satellite remote sensing. Hence there is a need for training courses, to establish a national oceanographic data center and a regional oceanographic data center for the Persian Gulf. It is also desirable to increase intraregional co-operation, possibly through a joint regional pilot project.

Merv Lynch presented a paper on “Remote sensing data issues for IOGOOS".

S. Rughooputh presented a paper on "Mauritius Marine and Coastal-Zone Information System".

The main purpose of the system is to provide a large and organized body of information, mostly in the form of maps, as a geographical information system, for planners, scientists, and decision-makers. The information base comprises some 30,000 maps organized in some 12 modules, covering all aspects of the geography of the Island of Mauritius. Some of these maps concern the coastal zone and territorial waters. One likely to be most useful is a shore classification.

Following some discussion of the presentations, the Workshop Chairman summarized the conclusions reached. Regarding data exchange, some of the problems are technical. The hardware and software needs of users need to be determined. Duplication (in data acquisition, processing etc.) must be avoided and made unnecessary by full and free access by all participants in IOGOOS pilot projects to all data relevant data sources. The needs of the Ocean Dynamics and Climate pilot projects are reasonably well met, now, but those in Coastal Ocean Observing are more difficult to meet, because the algorithms are more complex, and compliance with standards and protocols for measurements and for data products is more difficult to achieve. The priority for the coastal pilot projects is the detection of environmental change (mitigation/degradation), and for this it is necessary to concentrate on quality control of the data.

There are also some pragmatic questions, particularly regarding costs and title to data or data products, to be resolved. High spatial- and spectral-resolution data may be necessary for some purposes but are costly, so hard choices often have to be made.

Planned actions are to prepare:

•   a resource directory of satellites and their data products—descriptors, accuracy, spatial and temporal resolution, availability (real time, delayed time)

•   an inventory of research and capacity-building centres

•   a list of specific needs for capacity-building with respect to scatterometry, altimetry, inshore currents, sea-surface temperature and ocean fronts, and the oceanic water column (chlorophyll a, suspended sediments, dissolved organic compounds, light attenuation etc.).