Northern
Hemisphere Summer (1995)A joint effort between NASA and the French space agency to study Earth's oceans, the TOPEX/POSEIDON mission will observe the global ocean circulation for 3-5 years. The oceans play a fundamental role in maintaining the habitable climate we experience on Earth by transporting an enormous amount of heat through large-scale circulation systems. Understanding the dynamics of ocean circulation and the role this circulation plays in climate change is the main goal of the TOPEX/POSEIDON mission. The satellite travels in an orbit that allows coverage of 95% of the ice-free oceans every 10 days. The satellite measures sea levels, current variations, effects of currents on global climate change, and provides information about tides, waves, and wind. The images are "false color" images. That is, different measured values have been assigned different colors to make them easier to see. Note that when images are labeled winter or summer, this refers to the Northern Hemisphere perspective.
2. The satellite images below show the amount of water vapor in the atmosphere, which is heated indirectly. First, the sun heats ocean water, some of which evaporates and rises. As the air rises, it cools and condenses, thus releasing heat into the atmosphere. This process is called latent heat. The TOPEX/POSEIDON satellite is able to measure the amount of water vapor in the air, an indication of where and how much air is rising. Understanding the transfer of heat by this process is important to understanding the overall heat balance of Earth. Click on the summer image to get larger-sized versions of the images.
Click on Atmospheric Circulation (below) to see a diagram of generalized wind patterns (you may want to print this diagram on your local printer). The Atmospheric Circulation diagram shows generalized wind patterns on Earth's surface. It does not account for the influence of continents. A persistent low pressure zone is created over the equator (ITCZ), where massive amounts of evaporation cause air to rise. The solid lines and arrows show generalized wind patterns on Earth's surface. The dotted lines and arrows show how the lower atmosphere circulates (above Earth's surface). For example, air is shown rising over the ITCZ (low pressure zone) and falling over the subtropical high pressure zone (around 30 degree N and S latitude).
Northern
Hemisphere Summer (1995)
Northern Hemisphere Winter (1995)
(a.) Where are the areas of highest water vapor content in the atmosphere and how do these areas correlate to the climate belts shown in the Atmospheric Circulation diagram?
(b.) Where are the areas of lowest water vapor content and how do these areas correlate to the climate belts shown in the Atmospheric Circulation diagram?
(c.) Compare the winter and summer images. How do the locations of high and low atmospheric water vapor change from summer to winter (Northern Hemisphere perspective)?
3. The upper two satellite images show world-wide wind speeds during the Northern Hemisphere summer (left side) and winter (right side). The winds drive surface currents and also create waves that move energy across the ocean's surface. The lower two images show wave height variations in the world ocean during the Northern Hemisphere summer (left side) and winter (right side). If necessary, widen the viewing window so that the two images are adjacent to each other. Click on the upper left image to obtain larger-sized versions.
Above: Summer winds; Below: Summer waves. Above: Winter winds; Below: Winter waves
(a.) Where are the areas of high speed and low speed surface winds and and how do these areas correlate to the wind belts shown on the Atmospheric Circulation diagram?
summer high-speed winds:
summer low-speed winds:
winter high-speed winds:
winter low-speed winds:
(b.) Where are the areas of large waves and how do these areas correlate to wind speeds?
summer:
winter: