Why we need sustained observations
The oceans are grossly under-sampled in space and time, yet many of the fundamental questions of both scientific and practical importance depend on understanding change and variability at time-scales from days to decades and from local, to regional, to ocean-basin, and to global scales.
No single measurement technique can provide all the information needed. For example, whilst satellites give good spatial coverage of the oceans, the time resolution is usually low (many days between satellite passes) and space-borne instruments measure only the surface skin of the sea. Likewise, instruments moored to the sea-floor and so located at fixed points in space can give very detailed information about changes in time at these locations – but such instrument moorings are very expensive and so are found in very few locations in the oceans. Drifting buoys and opportunistic use of commercial ships help fill data gaps, but have their own limitations.
The broad approaches to measurement of the oceans include the following, with the specific programmes NOC and its Partners are contributing to listed under each:
- Satellites and aircraft – surface measurements over wide areas.
- Moored buoys and observatories – detailed measurements at fixed locations examples:
- Drifting buoys and profiling floats – subsurface measurements of a few parameters at many locations examples
- Repeat sections – repeated detailed measurements across extended transect lines of the ocean (sometimes sea surface to sea floor and from coast to coast across an entire ocean basin by research ship)
- Ships of opportunity –surface measurement of a few parameters from commercial cargo and passenger ships to improve spatial coverage - there are many more commercial ships than dedicated research ships ;
- Coastal sampling – measurements that can made from the coast - coastal sea level, temperature, shore dwelling marine plants and animals.
An important priority for the future is to reduce the dependence of oceanographers on very expensive research ships for the more routine long-term measurements.
This is why there is increasing focus on autonomous vehicles like “gliders”, “autonomous underwater vehicles - AUVs” and “profiling floats” (for more information visit our technology section). In this way we hope to increase the spatial and time density of sampling in the oceans.
This will free research ships to concentrate on their real purpose as mobile laboratories needed to enable large teams of researchers to undertake experimental work in remote locations at sea, where human intervention is needed.
The ocean observing system relies upon combining data from all the available measurement platforms. The effort to observe the oceans needs collaboration and partnership. No one country, let alone any one institution, can work alone.inherently
