Archive for June, 2012

new video series from the National Research Council  summarizes what scientists have learned about global warming and climate change.  It’s difficult to pack decades of complex research into short video snippets, but the makers of these videos have done an excellent job. As you watch, keep an eye out for mentions of the key role that remote sensing has played in advancing climate science. Also, look for the numerous data visualizations produced by the Scientific Visualization Studio at Goddard Space Flight Center that made the cut.

Congratulations to Alexandre Mathieu for being the first person to correctly identify our Satellite Puzzler from last week. We posted a full caption that explains the image in our Natural Hazards section yesterday, and it appeared at the top of our site as the Image of the Day on June 21st.

The image above is a bonus shot showing a detailed view of the two landslides. It was taken from an aircraft on February 10, 2011. Many thanks to Caner Zanbak for providing the aerial image and to everybody who participated (including our fans on Facebook). Look for the next puzzler in July.

Silent Spring Turns 50

June 19th, 2012 by Michon Scott

On June 16, 1962, The New Yorker began publishing a serialized version of Silent Spring by Rachel Carson. Spring would eventually turn silent, Carson warned, because widespread pesticide use was killing so many birds that there might be none left to sing. The book provoked a strong reaction from the pesticide industry, but also led to tighter restrictions on pesticide use in the United States and other nations.

Born in 1907, Rachel Carson studied at The Johns Hopkins University and the Marine Biological Laboratory. She was the second woman hired by the U.S. Bureau of Fisheries for a non-secretarial position. In her spare time, she wrote newspaper and magazine articles. Between 1941 and 1955, she published three books about the ocean, leaving the fisheries bureau in 1952 to become a full-time writer. A decade later, she completed the book that made her beloved by some and despised by others.

Rachel Carson in 1944. Image courtesy of the National Conservation Training Archives.

When Carson wrote Silent Spring, dichlorodiphenyltrichloroethane (better known as DDT) was frequently used as an insecticide in domestic and agricultural applications. At the same time, multiple bird species were showing signs of decline. Carson connected the dots between pesticide use, wildlife decline, and human health.

One common misconception about Rachel Carson’s work is that she opposed all use of DDT, even when it could prevent the spread of malaria. Although she described dire scenarios of how pesticides might affect nature and people, she didn’t argue for an end to all DDT use. Instead, she argued for more cautious, targeted uses. A Nature article commemorating the anniversary of her book reported that the pesticide restrictions eventually implemented probably left DDT more effective in fighting malaria because pests had fewer opportunities to adapt and evolve.

Carson faced a firestorm of criticism for her book, but helped spur environmentalism in the United States and abroad. She did not live to see many of the consequences of her work as she had breast cancer when Silent Spring was published and died from it in 1964. As she wrote her book, iconic birds such as the American bald eagle were in decline; but by 2007, the bald eagle was removed from the U.S. Endangered Species list.

To learn more about Rachel Carson, please see the Earth Observatory feature article by guest author Brian Payton.

Reference: Dunn, R. (2012) In retrospect: Silent Spring. Nature, 485, 578–579

 

Tornado Tracks

June 14th, 2012 by Michon Scott

Tornadoes plague the central and eastern sections of the contiguous United States far more than the western portion. That much is obvious from this map showing 56 years of tornado tracks, from 1950 through 2006.

Tornado tracks

Image courtesy John Nelson, IDV Solutions.

This map breaks down tornadoes by strength based on the Fujita scale. Stronger tornadoes appear as brighter lines. (An enhanced Fujita scale was implemented in 2007, but these tornado tracks were classified according to the earlier version.)

One prerequisite for tornado formation is humidity, which is much greater in the east than in the west. But topography also plays a role; few tornadoes form over mountainous West Virginia, for instance.

This map was created by John Nelson of IDV Solutions. He obtained the data through Data.gov, which was set up to “increase public access to high value, machine readable datasets” generated by the U.S. government. A high-resolution version of this image is available here.

EO’s Satellite Puzzler: June 2012

June 12th, 2012 by Adam Voiland

Every month or so, NASA Earth Observatory will offer up a puzzling satellite image here on Earth Matters. The first one is above. Your challenge is to use the comments section below to tell us what part of the world we’re looking at, when the image was acquired, and what’s happening in the scene.

How to answer. Your answer can be a few words or several paragraphs.  (Just try to keep it shorter than 300-400 words).  You might simply tell us what part of the world an image shows. Or you can dig deeper and tell us what satellite and instrument produced the image, what bands were used to create the image, and what those tiny specks of tan are in the corner. If you think something is interesting or noteworthy about an image, tell us all about it.

The prize. We can’t offer prize money for being the first to respond or for digging up the most interesting kernels of information. But, we can promise you credit and glory (well, maybe just credit). Roughly one week after a “mystery image” appears on the blog, we will post an annotated and captioned version as our Image of the Day.  In the credits, we’ll acknowledge the person who was first to correctly ID an image. We’ll also recognize people who offer the most interesting tidbits of information. Please include your preferred name or alias with your comment. If you work for an institution that you want us to recognize, please mention that as well.

A brush with fame. We’re not exactly TMZ.com, but our readership isn’t small either. Winners of the puzzler will contribute—and be recognized for doing so—to an article that we’ll share with our more than 100,000 subscribers, Facebook friends, and Twitter followers.  And that’s just the bare minimum. The caption you help us write might just be the next one that goes viral.

You can read more about the origins of the satellite puzzler here. Good luck!

Here at the Earth Observatory, we sift through a constant stream of data and imagery that flows in from a range of satellite, airborne, and ground-based sensors. As a result, the images we share on our website really run the gamut.

Many are true-color images that look like what your naked eye would see if you happened to be strapped to an Earth-observing satellite. Others are false-color views based on data from parts of the electromagnetic spectrum invisible to the naked eye.  (Here’s one  image of a burn scar that will give you a sense of the difference.)

Some EO images come from instruments that view broad horizontal swaths of Earth’s surface (see this example from MODIS); others come from instruments that observe thin slices of the atmosphere (see this example from CALIPSO). Some stills capture just a moment of time, while other images represent long stretches of it. Some even offer glimpses into simulated worlds derived from computer models (see this example from the GEOS-5 model).

Sometimes we find the images inspiring, sometimes disorienting, sometimes sobering, and sometimes heartbreaking. Occasionally, they’re simply bizarre. But if we’ve learned anything over the past 13 years, it’s that every image has a unique story behind it.  Sometimes the story is obvious; but other times it takes us months to years to piece together.

The fun part — for science junkies like us, at least — is the hunt for information. We figure that you might enjoy the hunt, too, so we’re adding a contest — EO’s Satellite Puzzler — that will allow you to give it a try. Every month or so, we’ll offer up a mystery image on Earth Matters. The first offering will come on June 12, 2012.

Your challenge is to use the blog comments section to tell us what part of the world we’re looking at, when the image was acquired, and what’s happening in the scene.

How to answer. Your answer can be a few words or several paragraphs.  (Just try to keep it shorter than 300-400 words).  You might simply tell us what part of the world an image shows. Or you can dig deeper and tell us what satellite and instrument produced the image, what bands were used to create the image, and what those tiny specks of tan are in the corner. If you think something is interesting or noteworthy about an image, tell us about it.

The prize. We can’t offer prize money for being the first to respond or for digging up the most interesting kernels of information. But, we can promise you credit and glory (well, maybe just credit). Roughly one week after a “mystery image” appears on the blog, we will post an annotated and captioned version as our Image of the Day.  In the credits, we’ll credit the person who was first to correctly ID an image. We’ll also recognize people who offer the most interesting tidbits of information. Please include your preferred name or alias with your comment.

A brush with fame. We’re not exactly TMZ, but our readership isn’t small either. Winners will contribute — and be recognized for doing so — to an article that we’ll share with our more than 100,000 subscribersFacebook friends, and Twitter followers.  And that’s just the bare minimum. The caption you help us write might just be the next one that goes viral.

Good luck!

Here at the Earth Observatory we know as well as anybody that explaining the nuance and complexity of climate modeling isn’t easy.

In May, Nature Climate Change published a study pointing out that the number of news articles that mention climate change has been declining since 2007. There was a slight increase in mentions following the “Climategate” scandal in 2009, but the number has fallen rapidly since then (see the dashed line below).

Climate models are especially unpopular. Just a tiny fraction of the articles about climate science mention models (see the solid black line in the graph above). And, among the influential newspapers, that number is declining (see graph below).

When climate models do appear in the news, they’re often flagged as inaccurate, and political opinion outlets — rather than news outlets — account for a surprisingly large percentage of the mentions. Twice as many of the media outlets that mentioned climate models did so in a negative rather than a positive light, the study found. Political commentary outlets — The Rush Limbaugh Show, The Nation and The National Review — had the highest frequency of negative content about climate models, but a variety of other news outlets had ample negative content about models as well.

That’s surprising given the central role that modeling has played in revealing key aspects of climate science and in how the Earth works at a basic level. If you attend a scientific meeting these days, you’ll find there are few Earth science topics that don’t involve some sort of modeling. Want to know, for example, whether the plume from the huge fire burning in New Mexico is going to blow into Albuquerque? You need a model. Whether that hurricane brewing in the Gulf of Mexico will be coming to your city? You need a model. Whether there’s enough groundwater for your soybean crop to thrive? Again, you might well get your answer from a model. See the video below to see how researchers are predicting the severity of the Amazon fire season months in advance with the help of models.

Most earth science models, it’s worth noting, base their output on huge amounts of real observations; scientific modelers are not just pulling numbers from thin air. One model based at Goddard called the Modern Era Retrospective-analysis for Research and Applications (MERRA), for example, has ingested more than 50 billion satellite observations made since NASA launched the Terra satellite — and a new era of Earth observations — in 1999. Another model called GEOS-5, one of the highest-resolution models, also ingests huge amounts of data from the real world. GEOS-5 simulated the massive winter storm that struck the eastern United States in 2010 with remarkable accuracy.

Models are not just for earth science. The same sort of complex, numerical models are used all over the sciences. Alfio Quarteroni, a professor of mathematics at a university in Switzerland, laid out a few of them in an article in Notices of the Mathematical Society in 2009.

Mach number and streamlines on the X29 experimental aircraft.

Credit: Notices of the AMS/Alfio Quarteroni

Aerospace engineers, he points out, use numerical models of fluid dynamics to make wingtips and fuselages more aerodynamic. Likewise, cardiovascular researchers take advantage of similar models to calculate how quickly blood flows through key arteries and how much stress the flow puts on artery walls as they narrow. Quarteroni has even used fluid dynamics models to try to figure out the best way to sail in different wind conditions.

Credit: Notices of the AMS/Alfio Quarteroni

Atmospheric scientists would be the first to point out that climate models aren’t always perfect. But as NASA modeler Gavin Schmidt pointed out in this Physics World article (which is worth the read if you want to understand what climate models can and can’t do), that lack of perfection doesn’t mean they’re not useful.

The Big Picture around a Little Swamp

June 6th, 2012 by Michon Scott

The Earth Observatory image of the day for June 5 shows flooding in Botswana’s Savuti River and Savuti Swamp. The abundant water turns out to be a very small part of a much bigger picture.

The Savuti Swamp sits within the Kalahari Desert, which stretches across Namibia, Angola, Zambia, South Africa, and most of Botswana. More of a sandy savannah than an actual desert, the Kalahari has wet and dry seasons that cause significant differences in vegetation. When the region is plunged into drought, an inland river delta, the Okavango, provides life-sustaining water for the wildlife. Since 2009, that water supply has been more abundant than usual, and the water has overflowed into other waterways in the region.

In 2009, the Okavango started experiencing record floods. “We first saw good flooding in Lake Ngami a few years back,” said Frank Eckardt of the University of Cape Town. “We have seen the Boteti River in flood since 2009 and also water in Lake Xau, southeast of the Okavango Delta.”

The satellite images below were acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on April 28, 2012. The first image uses a combination of visible and infrared light to better distinguish between water and land. Water is navy blue, vegetation is bright green, and bare ground is earth-toned. The imagery shows not only abundant but early water: flows have arrived in the Okavango Detla well ahead of schedule (usually July) and the delta is overflowing.

Okavango Delta region

The area outlined in white above is shown in this next close-up view of the Savuti channel and swamp that was featured as our image of the day. Impressive when well-watered, the swamp is in fact just a small part of a large network of rivers and basins.

Selinda and Savuti Channels

“We had in concurrence the highest flood on record in the Cuando River and the flood in the Okavango River pushing through the Selinda Channel, the first time I have seen that documented,” said Guido van Langenhove of Hydrological Services Namibia. “The combined waters then reactivated the Linyanti River, which had been drying out since 1982, to reach the overflows/backwater of the Zambezi River through the Chobe River (Lake Liambezi).” Wetter conditions were apparent in the Bukalo Channel in 2011.

Van Langenhove explains that water has also started flowing through the Savuti Channel to the Mababe Depression, a 50-by-90-kilometer (30-by-60-mile) heart-shaped basin that normally receives little water.

The skinny strip of land jutting out from Namibia eastward is known as the Caprivi Strip. The Zambezi floodplain sits at the easternmost extent of this strip, and flooding occurred in that region before 2009.

References

Burrough, S.L., Thomas, D.S.G. (2008) Late Quaternary lake-level fluctuations in the Mababe Depression: Middle Kalahari palaeolakes and the role of Zambezi inflows. Quaternary Research, 69(3), 388-403.

Okavango-Delta.net. Okavango Delta Information. Accessed June 4, 2012.

I Can See My Home from Here — Landsat Contest

June 4th, 2012 by Mike Carlowicz

From the Landsat team at NASA and the U.S. Geological Survey…

To celebrate the 40th anniversary of the Landsat Earth-observing program — which first rocketed into space on July 23, 1972 — NASA and the U.S. Geological Survey will be giving something special to members of the American public. NASA will create customized Landsat chronicles of changing local landscapes for six U.S. citizens who enter the “My American Landscape” contest.

To enter, all you have to do is send an e-mail describing the landscape changes in your home area and what you hope to learn about them from Landsat’s four decades of observations from space. The deadline for submissions is Wednesday, June 6, 2012. Contest winners will be announced live on NASA Television at a Landsat 40th anniversary press briefing on Monday, July 23. Click here for more details.

How to Enter

Answer the following questions in an email to:

HQ-LandsatContest@mail.nasa.gov

1) What types of landscape changes interest you in your area? Select one or more from this list: farms and fields; forests; cities and suburbs; lakes, rivers, and coasts; natural disasters; wildlife habitat.

2) Describe in at least 100 words the local changes you are interested in and what you hope to learn about them from a Landsat “space chronicle.”

3) Your name
4) The county and state where you live
5) Your e-mail address