ramifications for quantifying and predicting sea-level rise (Cabanes et al. 2001). Recent work suggests that thermal expansion of the surface ocean (upper 500 m) can fully explain the sea-level rise of 3.2 (± 0.2) mm per year observed by the satellite TOPEX/Poseidon (Cabanes et al. 2001).
PREVALENCE OF DYNAMIC FEATURES
The ability to observe the ocean surface from space has profoundly altered the way the ocean is viewed. The Coastal Zone Color Scanner (CZCS), launched aboard the Nimbus 7 satellite in 1978, provided the first satellite observations used to quantify the chlorophyll concentration in the upper ocean (see Chapter 9, Box 9.3). The first images of surface chlorophyll distributions were truly astonishing, revealing a high degree of spatial variability never fully appreciated before satellites (Figure 8.3). The availability of global maps of chlorophyll, an estimate for marine plant biomass, has opened new avenues of research and changed the conduct of biological oceanography in many ways.
Mesoscale features such as vortices and jets, as well as tidal fronts and river plumes, had been seen previously in aerial photographs and thermal imagery from the TIROS satellites, but ocean color images revealed entirely new features. An example of this is the vast extent of the Amazon River plume stretching many thousands of kilometers across the Atlantic (Figure 8.4, Muller-Karger et al. 1988). The plume’s temperature does not provide sufficient contrast
FIGURE 8.3 CZCS image of phytoplankton pigments in the North Atlantic Ocean. CZCS was flown on the Nimbus 7 satellite launched in 1978. CZCS was the first multispectral imager designed specifically for satellite observations of ocean color variations. One of the primary determinants of ocean color is the concentration of chlorophyll pigments in the water. High concentrations of chlorophyll (red and brown areas in the image) are seen along the continental shelf (1) and above Georges Bank (2) where the biological productivity is high. Intermediate concentrations of chlorophyll pigments are shown in green, and the lowest levels are blue. Notice that the Gulf Stream (3) and the warm core eddy to the north (blue circle) have very low concentrations, reflecting the fact that the stream and the Sargasso Sea to the south are relatively nutrient poor. SOURCE: NASA.