Future challenges in shelf seas - Introduction to the Physical and Biological Oceanography of Shelf Seas - page 356

technical problem, one that we often come across in interdisciplinary research. The
properties of the sea that allow us to describe the physics of the ocean are often easily
measured (e.g. salinity and temperature, well-resolved vertical profiles of currents).
Making parallel measurements of the biology, particularly as the size of an organism
increases and its number density in the ocean decreases, requires some innovation.
The emergence of low-powered digital cameras, autonomous vehicles and combin-
ations of acoustic techniques (e.g. vessel-mounted ADCPs and zooplankton/fish echo
sounders) are all areas where new insights into physical drivers of ecosystems are
possible.

11.1.4 Observations and numerical models

In addition to the technical challenges in linking physical and biological observations
at the right scales, there is a similar challenge associated with model development and
our ability to provide suitable observational data for validation. Look again at the
image of internal waves generated by flow past a seamount in Fig. 11.1 . How would
you try to observe that in the real ocean? We could acquire images from satellite-
borne radar (e.g. Fig. 10.13a ), but the sensitivity of such imagery to sea state and the
orbital characteristics of the satellite are not amenable to gaining any insight into the
temporal evolution of the waves, which would be vital for any sensible model
validation. Also, we would really want to know the vertical density structure under-
neath the sea surface rather than just the surface manifestation of the waves viewed
by the satellite sensor. Perhaps a survey with an autonomous vehicle would do the
job? Assume the vehicle can travel at 1 m s 1 , and that we want to survey an area
about 10 km 10 km. Spacing our survey tracks 1 km apart would lead to a total

survey length of 109 km, which would take about 1 day 6 hours to complete. The
internal wave field is likely to modify substantially over that time, so our survey could
not be viewed as synoptic. A research vessel operating acoustics (e.g. Fig. 1.6 ) and
(for internal waves closer to the sea surface) towing an undulating vehicle ( Fig. 1.5 )at
8 knots could get round the survey in 4 hours: still not synoptic, but getting much
closer to what we might want to provide the modellers with. Models deal with noise-
free, clear, synoptic (and seductive) fields of any data type that the modeller wants to
see. Observationalists work from slow research vessels, in a real, noisy environment,
and cannot measure many of the modelled parameters at scales compatible with the
physics. Particularly in interdisciplinary oceanography, not just in the shelf seas, this
is an area of significant challenge; combining models and observations together in a
meaningful and insightful way which goes beyond simply working on the same
project with sets of different tools and different approaches.

11.2 Regional questions

......................................................................................................................
There remain many interesting topics for research in those regions of the shelf seas
globally that have received less research attention compared to the temperate shelf
regions on which our work, and this topic, have mainly focused. These other regions