DISAPPEARING WATER: THE ARAL SEA OVER TIME, FROM 1973 TO 2001 A ...
DISAPPEARING WATER: THE ARAL SEA OVER TIME, FROM 1973 TO 2001 A time series is a powerful illustrative tool. Where in the case of Las Vegas we see the direct effects of people on the land, in the case of the Aral Sea, separating the countries of Kazakhstan and Uzbekistan, we see indirect, but no less dramatic effects on a different part of the world. The Aral Sea is actually not a sea at all. It is an immense lake, a body of fresh water, although that particular description of its contents might now be more a figure of speech than practical fact. In the last thirty years, more than sixty percent of the lake has disappeared. As you'll see in the visualization, the change over time is dramatic. In the 1970s, farmers and state offices opened significant diversions from the rivers supplying water to the lake, sending millions of gallons to irrigate cotton fields and rice paddies. So voluminous were these irrigation sluices that concentrations of salts and minerals began to rise in the shrinking body of water. That change in chemistry has led to staggering alterations in the lakes ecology, causing precipitous drops in the Arals fish population. A secondary effect of this reduction in the Aral Seas overall size is the rapid exposure of the lake bed. Powerful winds that blow across this part of Asia routinely pick up and deposit tens of thousands of tons of now exposed soil every year. This has not only contributed to significant reduction in breathable air quality for nearby residents, but also appreciably affected crop yields due to those heavily salt laden particles falling on arable land. In the following sequence of images, we see a series of Landsat scenes taken several years apart. As the years pass, we see the profound reduction in overall area covered by the Aral, and a commensurate increase in land area as the floor of the sea now lies exposed.
Altimeters onboard satellites such as Jason-2 measure sea surface height and other ...
Altimeters onboard satellites such as Jason-2 measure sea surface height and other characteristics of the ocean surface. These characteristics are linked to underlying processes and structures, making altimetry data useful for understanding the full depth of the global ocean. This 75-minute module explores major discoveries made possible by altimetry data in oceanography, marine meteorology, the marine geosciences, climate studies, the cryosphere, and hydrology. For example, altimeters have played a vital role in detecting and monitoring sea level rise and its relation to climate change. The module also describes many of the practical applications of altimetry data, for example, in hurricane forecasting and monitoring climate events such as ENSO. Finally, the module describes Jason-2, which was launched in 2008, its products and services, and the Ocean Surface Topography Mission (OSTM), of which it is a part. OSTM is a collaboration between EUMETSAT and CNES (Europe) and NOAA and NASA (United States).