Much of the research in physical oceanography in the next two decades will be in connection with the World Climate Research Programme. One of the emphases in this programme has been the period from a month to a few decades, in which the dynamics of the ocean are particularly important.
Namibia has one of the driest climates in Africa, with an amazing 300 days of sunshine a year, and is one of the most welcoming places to spend your time, but before you pack your bikini and head for the beach in this sunny, hospitable country -think again.
While the Atlantic Coast of Namibia is indeed an arid and beautiful sandy shore, it is hardly a beachgoer’s paradise. Ocean processes involved in this range include heat transport and storage throughout the upper layers of the ocean down through
the main thermocline, the dynamics of all major current systems, interactions with sea ice, and large-scale ocean atmosphere coupling. Oceanographers and meteorologists will need to collaborate in programmes involving the joint analysis of atmospheric and oceanic data, and the development of coupled ocean-atmosphere models designed for climate studies in these time scales. The storage capacity of the oceans for carbon dioxide (CO2) is central to evaluating the effect of the increase in global CO2 caused by fossil fuel burning and deforestation on climate.
In the past, this problem has been the province of chemical oceanographers who have used rather simple box models. A stronger involvement of physical oceanographers using more realistic and sophisticated general-circulation models is now called for. Collaboration of chemical and physical oceanographers is needed to incorporate realistic multicomponent carbon chemistry into the physical general-circulation models.
The increasing emphasis on climate dynamics and variability could significantly change the physical oceanographers’ approach to ocean dynamics. Traditionally, large-scale dynamical oceanography has concentrated on understanding the global mean circulation of the ocean.
Process studies oriented towards small-scale interactions between eddies, internal waves, convective overturning, etc, have largely been motivated by the desire to understand the sub-grid scale phenomena that maintain the mean circulation. Existing models of the global ocean circulation could afford to be computer-costly because they were designed primarily to simulate a single steady state circulation.
However, for climate studies, the emphasis on variations in the large-scale circulation rather than the mean state itself requires more efficient models suitable for extended series of numerical experiments covering a wide variety of temporal and spatial scales of variability.
Theoretical and numerical investigations will be needed to identify the relevant internal dynamics of the ocean associated with different ranges of the spectrum, and to design the models to include only the dynamics relevant to the scales selected for study while filtering out components that may require considerable computer power to evaluate, but do not contribute significantly to the ocean response in the chosen spectral range.
A careful analysis of the ocean response characteristics on different scales is also a prerequisite for a properly-designed ocean monitoring system for climate studies. In contrast to the World Weather Watch (WWW) system of the World Meteorological Organisation (WMO), which is designed (within the limitations of cost and geography) to be as uniform as possible, an optimal sampling scheme for monitoring the oceans would almost certainly be strongly inhomogeneous.
The presence of meridional boundaries and the associated western intensification of currents leads to strong lateral inhomogeneities in the space and time scales of ocean dynamics. The thermal and wind-stress forcing acting from above on the stably-stratified oceans leads also to a strong time-scale separation in the vertical.
Thus, in contrast to the homogeneous dynamics of the tropospheric atmosphere, the global ocean circulation is strongly structured in terms of dynamically-distinct regions.
A monitoring system must allow
for the different response scales in these different regions, while considering also the interaction between regions within the entire coupled ocean-atmosphere system. The widespread reluctance of physical oceanographers to make specific recommendations for an ocean-monitoring system may be attributed largely to the present lack of understanding of the dynamical interplay within this complex multiregional system, together with the apprehension of the long-term commitment of considerable resources implied by any form of oceanic monitoring.
With some optimism, it may be anticipated that advances in our theoretical understanding and modelling of the time-dependent global ocean circulation will generate sufficient confidence in the coming decades to permit defining and gradually implementing an ocean monitoring system to provide the necessary database for future climate studies, and possible for climate prediction. Predicting the marine environment, because of the increasing exploitation of the oceans’ resources, and the accompanying growth in offshore technology, expanded support is required from physical oceanographers to provide statistics and forecasts on the state of the environment (often extreme and hostile) in which offshore operations are carried out. Similar information is needed for ship routing.
There will be a need for complete services that extend from global data- collection via satellite, and numerical prediction at a few large forecast centres, to routing and operational recommendations, distributed again via satellites to individual operators. Similar demands on physical oceanographers may also be expected from agencies responsible for monitoring and predicting pollution (e.g. detection and prediction of drifting pollutants and oil spills).
Scientifically, the modelling of surface waves, currents, tides, storm surges and transport of contaminants has advanced to a stage where useful predictions could be provided today on a routine basis for marine operations.
However, in many countries (especially developing countries) an adequate operational infrastructure for routine forecasting does not exist. Since weather forecasts represent an important input
for most marine forecasts, the task will need to be tackled jointly with the meteorological agencies. Whatever the weather, the West Coast is proving to be the stuff that campfire stories are made of, with haunting scenes and activities for all to enjoy.
*Dr Moses Amweelo is a former Minister of Works, Transport and Communication. He is currently a part-time lecturer at IUM and UNAM. He earned a doctorate in Technical Science, Industrial Engineering and Management from the International Transport Academy (St Petersburg, Russia).