Physical oceanography is the study of the physical properties and dynamic processes of the oceans. Physical oceanographers study the interaction of the ocean with the atmosphere, how the ocean stores and releases heat, the physical properties (or chemical content) of water throughout the ocean, and the formation and movement of currents and coastal dynamics. In order to understand these phenomena, researchers at NASA measure ocean surface topography, sea surface temperature, the speed and direction of the winds over the ocean, and soon, sea surface salinity (salt content). From these data, scientists can further study ocean currents, and sea ice.
Satellites provide a double advantage over traditional ship-based measuring systems as they are able to provide continuous measurements on a global scale. A single global snapshot – which would be expensive and time-consuming, but possible from ships or buoys – fails to convey how the physical state of the ocean is changing. With satellite data, scientists can understand not only how the ocean behaves at a given point in time, but also how the ocean changes and fluctuates. For example the patterns of heat distribution within the ocean and the geographic extent of current systems affect climate and weather. A displacement of weather patterns can extend summer weather or lead to droughts or floods.
|The Physical Ocean|
|Ocean Surface Topography
NASA uses extremely precise measurements of the height of the ocean acquired from orbiting satellite instruments to map the topography of the ocean surface. Ocean Surface Topography (OST) data contains information that has practical applications in such areas as the study of worldwide weather and climate patterns, the monitoring of sea level evolution, and the protection of our ocean fisheries.
|Sea Surface Temperature
Instruments aboard NASA satellites use their vantage point from space to collect global measurements of the ocean’s surface temperature. By developing global, detailed, and decades-long views of Sea Surface Temperature (SST), data obtained from NASA satellites provide the basis for prediction of climate change, ocean currents, and global climate patterns like the potent El Niño-La Niña cycles.
|Sea Surface Winds
Winds are the largest source of momentum for the ocean surface. Winds have an impact on both individual currents and complete current systems. When observing ocean phenomenon, it is critical to consider winds as part of what we measure.
|Sea Surface Salinity
Sea Surface Salinity (SSS) tells us the about the concentration of dissolved salts in the upper centimeter of the ocean surface. Even small variations in SSS can have dramatic effects on the water cycle and ocean circulation.
|Ocean Surface Currents
The ocean is constantly in motion, with currents that travel both on the surface and in the depths. These movements carry water vast distances. Only from space can the true extent of currents be tracked in real time. NASA satellites employ a variety of instruments to interpret ocean currents.
Sea ice is formed when ocean water is cooled below its freezing temperature. Sea ice is important to the study of oceans because it impacts oceanic chemical and physical properties, density structure, oceanic dynamics, and exchanges between the ocean and the atmosphere. A variety of NASA instruments are used to measure and study sea ice from space.