Shelf seas, estuaries, and coasts

Abstract

This chapter reviews how satellite data contribute to the research and applications of oceanographic knowledge in shelf seas, estuaries, and coastal waters. The reason for devoting a chapter to this subject is that remote sensing in shallow seas and in the near-shore marine environment presents some challenges and opportunities that differ from those encountered in open-ocean satellite oceanography. Where the continental shelf extends more than a few tens of kilometers offshore the dynamics of water movement have a distinct character, which presents a variety of different phenomena to be observed and affects the way that satellite data are interpreted. This is developed in Section 13.2, which shows the importance of medium-resolution imaging sensors for shelf sea oceanography. Until quite recently, the use of altimetry in shelf seas was largely ruled out as impractical because of severe limitations of accuracy. However, recent research activity has pointed the way to promising developments in coastal altimetry, and these are outlined in Section 13.3. As we approach very close to the shore, or where the sea penetrates the coastline in estuaries, standard ocean-imaging sensors lack the required spatial resolution. Having to use alternative sensors has given a different character to the methods of coastal and estuarine remote sensing, which are outlined in Section 13.4, although there is scope here for little more than an introduction to what could become a fairly extensive subject if allied topics such as the remote sensing of lakes, deltas, and wetlands were included.