Archives for category: Earth Science

Satellites provide dramatic views of clouds, but in order to understand the processes that underlie how clouds form and evolve, scientists turn to complex computer models that simulate Earth’s atmosphere. By feeding a range of ground, aircraft and satellite data into Goddard’s Earth Observing System Model (GEOS-5), research meteorologists can see how closely the mathematical equations used to simulate atmospheric dynamics match reality. Such models are by no means perfect, but they have improved tremendously in recent years. The visualizations below, based on GEOS-5 model runs from February 2010, show how well the model reproduced the massive blizzard known as “Snowmaggedon.” In the visualization, watch Snowmaggedon’s sprawling, comma-shaped cloud system—complete with a tail that reaches all the way to the Caribbean—as it churns up the Eastern Seaboard dumping three feet of snow in some areas.

NASA Visualization Explorer, January 2012 

Ever notice how in many parts of the world, puffy, cauliflower-shaped cumulus clouds are more common in the summer? There’s a reason for this: thermal convection. In winter, the sun has less time to heat the surface and cause instability in the atmosphere. But during the summer, heat from the sun warms the land surfaces so much that pockets of hot air—scientists call them thermals—bubble upward much like steam in a pot of boiling water. As the hot air rises, the water vapor trapped within condenses into microscopic cloud droplets. If the air is humid enough, rapidly changing cumulus clouds puff up in the atmosphere, sometimes bulging to heights above 39,000 feet. Watch in the visualizations below—based on a climate model that simulated cloud formation during a Southern Hemisphere summer—how cumulus clouds pop up over the forests of Africa and South America.

NASA Visualization Explorer, January 2012

A new study led by a NASA scientist highlights 14 key air pollution control measures that, if implemented, could slow the pace of global warming, improve health and boost agricultural production.

The research, led by Drew Shindell of NASA’s Goddard Institute for Space Studies (GISS) in New York City, finds that focusing on these measures could slow mean global warming 0.9 ºF (0.5ºC) by 2050, increase global crop yields by up to 135 million metric tons per season and prevent hundreds of thousands of premature deaths each year. While all regions of the world would benefit, countries in Asia and the Middle East would see the biggest health and agricultural gains from emissions reductions.

“We’ve shown that implementing specific practical emissions reductions chosen to maximize climate benefits would also have important ‘win-win’ benefits for human health and agriculture,” said Shindell. The study was published today in the journal Science.

NASA, January 2012

A team of scientists have used the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite to confirm major reductions in the levels of a key air pollutant generated by coal power plants in the eastern United States. The pollutant, sulfur dioxide, contributes to the formation of acid rain and can cause serious health problems.

The scientists, led by an Environment Canada researcher, have shown that sulfur dioxide levels in the vicinity of major coal power plants have fallen by nearly half since 2005. The new findings, the first satellite observations of this type, confirm ground-based measurements of declining sulfur dioxide levels and demonstrate that scientists can potentially measure levels of harmful emissions throughout the world, even in places where ground monitoring is not extensive or does not exist. About two-thirds of sulfur dioxide pollution in American air comes from coal power plants. Geophysical Research Letters published details of the new research this month.

The scientists attribute the decline in sulfur dioxide to the Clean Air Interstate Rule, a rule passed by the U.S. Environmental Protection Agency in 2005 that called for deep cuts in sulfur dioxide emissions. In response to that rule, many power plants in the United States have installed desulfurization devices and taken other steps that limit the release of sulfur dioxide. The rule put a cap on emissions, but left it up to power companies to determine how to reduce emissions and allowed companies to trade pollution credits.

NASA, December 2011

The record-breaking drought in Texas that has fueled wildfires, decimated crops, and forced the sale of cattle herds has also reduced levels of groundwater to the lowest levels observed in more than 63 years. Groundwater is moisture trapped in pores in the soil and in underground gaps in rock, often known as aquifers.

The map above depicts the amount of groundwater stored underground in the continental United States on November 28, 2011, as compared to the long-term average from 1948 to 2011. Deep reds reveal the most depletion, with deep blues representing aquifers and soils that are nearly full. The maroon shading over eastern Texas, for example, shows that the ground has been this dry less than two percent of the time between 1948 and the present.

At the end of November 2011, groundwater supplies were extremely depleted in more than half of Texas, as well as parts of New Mexico, Louisiana, Alabama, and Georgia. The northeastern states and the High Plains appear saturated with water heading into winter months.

Earth Observatory, November 2011

The geological record holds clues that throughout Earth’s 4.5-billion-year lifetime massive supervolcanoes, far larger than Mount St. Helens or Mount Pinatubo, have erupted. However, despite the claims of those who fear 2012, there’s no evidence that such a supereruption is imminent.

What exactly is a “supervolcano” or a “supereruption?” Both terms are fairly new and favored by the media more than scientists, but geologists have begun to use them in recent years to refer to explosive volcanic eruptions that eject about ten thousand times the quantity of magma and ash that Mount St. Helens, one of the most explosive eruptions in recent years, expelled.

It’s hard to comprehend an eruption of that scope, but Earth’s surface has preserved distinctive clues of many massive supereruptions. Expansive layers of ash blanket large portions of many continents. And huge hollowed-out calderas – craters that can be as big as 60 miles (100 km) across left when a volcano collapses after emptying its entire magma chamber at once – serve as visceral reminders of past supereruptions in Indonesia, New Zealand, the United States, and Chile.

NASA, November 2011