Rapid Assessment of the Coastal Ocean Environment
201
This chapter is addressed to both ocean forecast scientific researchers and to
applied REA managers and naval officers. Thus some material will be of more or
less interest to each group.
11.1.1 Nowcasting and forecasting for REA
Mankind has leamed to intuitively assess weather and sea conditions and to predict their likely development from observations. In the first place the experience of
shepherds and fishermen is related to their home area and can only be relocated if
the same physical processes are dominant in another area. Universal environmental
assessment systems must include ali physics of potential relevance. The theory of
tides is an excellent example of a relocatable assessment system with long range
forecast capability. Prediction of ocean features that are less deterministically
forced, suffers from spatial scales being an order of magnitude smaller than in
meteorology. While in meteorology a worldwide observational network has constantly been maintained, a comparable oceanographic eddy resolving observation
system would still be too expensive. In oceanography detailed environmental information, though technically always possible, is only assembled in limited areas and
for limited time periods.
Operational oceanography that sustains the comparison with atmospheric
weather analysis and forecast must be based on a relocatable ocean assessment system that yields results within short time (order of a day) and, besides a description
of the present status, predicts changes in the ocean. As noted above, an ocean
assessment campaign that meets these requirements is called Rapid Environmental
Assessment (REA).
An REA operation is required whenever necessary informat ion cannot be
obtained from available sources. Pre-existing information usually provides good
estimates of ocean depth and climatological means of parameter fields such as temperature, salinity or nutrients. Even though for many applications this information
might already be sufficient, there are cases where small discrepancies between climatology and actual fields create large errors in a derived quantity. The requirements for parameter accuracy and spatial or temporal resolution depend on the
final products that are desired. They control the measurement strategy and the
numerical assessment and prediction tools to be applied.
11.1.2 Naval REA
Navy vessels are more affected by environmental conditions than merchant
ships. Currents and waves would impact navy ships or soldiers the same as in the
civilian world. However, certain specific environmental parameters have a meaning only in a military scenario. Sonar range, e.g., confines the ability to fight or
protect against an invisible enemy. Navy ships do have limited capability for environmental in situ measurements that can be combined with a priori knowledge.
Single point measurements however do not give full insight into the environmental
situation. On the contrary, the melding of a point measurement with climatology
can in some conditions be worse than the climatological database alone.
201
This chapter is addressed to both ocean forecast scientific researchers and to
applied REA managers and naval officers. Thus some material will be of more or
less interest to each group.
11.1.1 Nowcasting and forecasting for REA
Mankind has leamed to intuitively assess weather and sea conditions and to predict their likely development from observations. In the first place the experience of
shepherds and fishermen is related to their home area and can only be relocated if
the same physical processes are dominant in another area. Universal environmental
assessment systems must include ali physics of potential relevance. The theory of
tides is an excellent example of a relocatable assessment system with long range
forecast capability. Prediction of ocean features that are less deterministically
forced, suffers from spatial scales being an order of magnitude smaller than in
meteorology. While in meteorology a worldwide observational network has constantly been maintained, a comparable oceanographic eddy resolving observation
system would still be too expensive. In oceanography detailed environmental information, though technically always possible, is only assembled in limited areas and
for limited time periods.
Operational oceanography that sustains the comparison with atmospheric
weather analysis and forecast must be based on a relocatable ocean assessment system that yields results within short time (order of a day) and, besides a description
of the present status, predicts changes in the ocean. As noted above, an ocean
assessment campaign that meets these requirements is called Rapid Environmental
Assessment (REA).
An REA operation is required whenever necessary informat ion cannot be
obtained from available sources. Pre-existing information usually provides good
estimates of ocean depth and climatological means of parameter fields such as temperature, salinity or nutrients. Even though for many applications this information
might already be sufficient, there are cases where small discrepancies between climatology and actual fields create large errors in a derived quantity. The requirements for parameter accuracy and spatial or temporal resolution depend on the
final products that are desired. They control the measurement strategy and the
numerical assessment and prediction tools to be applied.
11.1.2 Naval REA
Navy vessels are more affected by environmental conditions than merchant
ships. Currents and waves would impact navy ships or soldiers the same as in the
civilian world. However, certain specific environmental parameters have a meaning only in a military scenario. Sonar range, e.g., confines the ability to fight or
protect against an invisible enemy. Navy ships do have limited capability for environmental in situ measurements that can be combined with a priori knowledge.
Single point measurements however do not give full insight into the environmental
situation. On the contrary, the melding of a point measurement with climatology
can in some conditions be worse than the climatological database alone.