Archive for the ‘Uncategorized’ Category

Matters of Scale, and Why They Matter

March 25th, 2013 by Jesse Allen

Recently, we published a data visualization showing tropospheric NO2 over the Indian Ocean. The effort got us to thinking about how we try to present data in a way that’s easy to interpret while staying true to the science.

The visualization below of satellite measurements of NO2 in the atmosphere revealed the location of shipping lanes in the Indian Ocean. Ships tend to pass consistently along the same paths — through the Red Sea, across the Arabian Sea, across the southern end of the Bay of Bengal, through the Malacca Straits — to major ports in eastern Asia. On any given day, the exhaust fumes from a few ships do not provide a dramatic signal. But by making a long-term average (2005 through 2012) of data, the small day-to-day fluctuations add up to a discernible signal.

Global NO2 (2005-2012)
Global NO2 palette

 

One of the other things we did in building this visualization was to mask the land surfaces with light grey, in order to emphasize the NO2 over the oceans. But what happens if we take off that gray blanket over the land masses?

Global NO2 (with land mask removed)
Global NO2 palette

Oh my! Pretty much anywhere there are people, there’s a saturated pool of NO2. All of Europe looks like a putrid mass of polluted air, as does eastern China, the cities of the Middle East, the Himalayan regions of India and Pakistan. In fact, pretty much anywhere there are significant human populations, there is NO2 running right off the scale! You can still see the ship tracks, but it’s the deep, over-saturated brown-orange that grabs your attention.

If you want to show concentrations over land, you need a breath of fresh air, like this:

Global NO2 (no land mask; scaled 0 - 20E15 molecules/cm^2)
Global NO2 palette (0 - 20E15 molecules/cm^2)

This is a better way to show NO2 emissions over land.  Distinct signals show up around industrialized cities in Europe, the Middle East, and southern Asia, as well as fire emissions in equatorial Africa. Eastern China is still a saturated mess, as are some of the major industrial areas elsewhere in China. Heavy industrialization and an increase in automobiles for transportation has resulted in levels of atmospheric pollution in China not seen since the 1940s to 60s in the U.S. and Europe.

But this third map scarcely shows the NO2 emissions over the sea, and the ship track signals are hardly discernible, even though we are still using the same exact set of data in all three visualizations. So what is going on?

Look carefully at the color palette, or scale bar, below each map describing how different colors reflect different concentrations of NO2. The high end of the scale has been changed; in fact, it has been multiplied by a factor of ten in the last version. When compared to land-based sources of pollution, ship tracks are quite faint. As much as ships contribute to NO2 pollution, they can’t compare to land-based sources.

That makes sense, if you think about it. If a single ship emitted the same amount of NO2 each day as a small coal-fired power plant, you would expect the signals to match. But the ship is not sitting still; it is moving back and forth across thousands of miles of open ocean and its emissions are thinned out over long distances and time. It is only when there are  hundreds of similar ships traveling along the same route that the signal begins to build; and even then, the emissions are still spread across a vast area in a way that land-based sources are not.

So for our story on ship tracks, we made the visualization with tight limits on the NOconcentration in order to bring out the signal from the noise. Had we not masked out the land sources, the ship tracks would have been  lost.

 

Tournament Earth: Only 8 Remain

March 18th, 2013 by Adam Voiland

How is your bracket looking now after Round 2 of Tournament Earth?

Cinderella Baja was finally taken out by the Black Marble, but two other high seeds remain: “Crack in the Ice” and “El Hierro.” If you want to dissect what went wrong (or right) with your picks last week, look below to see how the voting played out. In the data section, we saw the PIG Ice Crack blow out the North American heat wave image, which garnered just 22 percent of the vote. Voyager’s view of Earth also went down hard, earning just 37 percent of the vote against the solar flare.

Don’t forget to vote in the third round. Some key matchups to watch: #1 ranked City Lights of the United States is squaring off against #2 ranked Night Lights 2012. And in the true color section, the Black Marble faces the toughest competition it has seen yet from the solar flare image. Voting closes at 4pm Eastern Time on March 22.

The Black Marble (57%) vs. Baja California (43%)blackmarbletvsbaja


Solar Flares (63 %) vs. Voyager Far from Home (37 %)
earthVSvoyager


El Hierro (57%) vs. GOES Hurricane Sandy (43%)

IDL TIFF file


Hurricane Isaac (35%) vs. New Volcanic Island (65%)

isaacVSisalnd2012241


City Lights United States (66%) vs. Lights of London (34% )
IDL TIFF file


City Lights Nile (47%) vs. Flat Map Night Lights (53%)
nilevsglobalnightlights


PIG Ice Crack (78%) vs. North American Heat Wave (22%)

pigVScrack


Tree Map (48%) vs. Antarctic Sea Ice (52%)
treesVSice_2012270

 

Australia’s Angry Summer

March 6th, 2013 by Michon Scott

Australia is no stranger to fires, floods, drought, and heat. But a new report from the Australian Climate Commission not only points out that fire hazards and extreme weather events are worsening, it links them to a warming climate.

The report focuses on what it calls the “Angry Summer” of 2012/2013. The 90-day period included 123 broken records for maximum temperatures, heat waves, floods, and daily rainfall amounts. “The summer of 2012/2013 was Australia’s hottest summer since records began in 1910,” the report stated. The Angry Summer brought the highest area-averaged maximum temperature in Australia: 40.30°C (104.54°F). The summer also brought the longest stretch of high temperatures: for seven straight days (January 2–8), the average daily maximum temperature for the entire continent exceeded 39°C (102.2°F). This broke the previous record of four straight days above 39°C.

australialsta_amo_2013001

 

The report also made a starker point: “There have only been 21 days in 102 years where the average maximum temperature across Australia has exceeded 39°C; eight of these days happened this summer.”

High temperatures exacerbate fire danger, and the Australian summer of 2012/2013 brought major bushfires in New South Wales, Victoria, and Tasmania. Based on air temperature, humidity, drought, and wind speed, Australia’s forest fire danger index has historically used a scale from 1 to 100 to gauge the danger of bushfires. Starting in 2009, the index added a new fire danger rating above 100, termed “catastrophic,” reflecting a new fire-danger regime.

While some parts of Australia were on fire, other parts were under water. The Climate Commission discussed heavy rainfall, including torrential rains from cyclone Oswald that flooded parts of the Queensland coast in January 2013. The report stated that parts of the east coast broke rainfall records for the entire month in just the seven days of the storm. The report linked recent extreme rainfall events in eastern Australia to higher sea surface temperatures, which increase atmospheric water vapor and lead to greater precipitation.

From The Angry Summer, adapted from IPCC 2007.

From The Angry Summer, adapted from IPCC 2007.

The Climate Commission pointed out that Australia’s average temperature has increased by 0.9°C (1.6°F) since 1910, and went on to say that, while that temperature increase might seem small, “When the average temperature shifts, the temperatures at the hot and cold ends (tails) of the temperature range shift too. A small increase in the average temperature creates a much greater likelihood of very hot weather and a much lower likelihood of very cold weather.”

See the full report at http://climatecommission.gov.au/report/the-angry-summer/

Other Views of Storm Destruction on Cape Cod

February 26th, 2013 by Mike Carlowicz

Our image of the day on February 26 provided a satellite view of how a nor’easter can stir up the New England coast and its waters. Here are a few other views from the storm they called Nemo…

IMG_8745

A aerial photo from Kelsey-Kennard Airview shows the new breach in South Beach, just off the town of Chatham, Massachusetts.

WCVB television in Boston surveyed the destruction in the Cape Cod National Seashore. Click here to view.

Beach dunes, parking lots, boardwalks, stairways — along with waterfront homes — took a beating from the storm the media called “Nemo.” This YouTube video shows the wreckage at Coast Guard Beach, in Sandwich, and other points on Cape Cod, Massachusetts:

In Truro, the ocean breached the dunes and sent water into the Pamet River:

The Sun and the Television

January 28th, 2013 by Mike Carlowicz

Today we have a re-post from one of our colleagues on the sunny side of NASA. Karen C. Fox is a writer for NASA’s Heliophysics division.

A new kind of television recently made headlines at the 2013 Consumer Electronics Show: Ultra High Definition TV. With four times as many pixels as a current high definition (HD) TV, viewers reported being impressed with how crisp and vibrant the pictures appear.

This comes as no surprise to scientists who study the Sun using NASA’s Solar Dynamics Observatory (SDO). Its Atmospheric Imaging Assembly (AIA) and Helioseismic Magnetic Imager (HMI) together capture an image every second that is twice as large as what the ultra high-def screens can display. Such detailed pictures show features on the Sun that are as small as 200 miles across, helping researchers observe what causes giant eruptions known as coronal mass ejections (CME), which can travel toward Earth and interfere with our satellites.

One concern about the new TVs is that there’s not yet enough content to make use of the opulent amount of pixels. SDO can help with that. As of December 2012, the solar observatory had captured 100 million images, which — if watched at a standard video rate of 30 frames per second — would mean a viewer could watch eight hours of Sun movies a day for almost four months.

For HD imagery from NASA’s SDO mission, visit: www.nasa.gov/sdo

A New Perspective on Precipitation

January 23rd, 2013 by Michon Scott

In late 2012, floods swamped the United Kingdom and news reports said tens of thousands of residents had been affected. It was the kind of natural hazard the Earth Observatory tries to cover, but floods can be hard to see. When heavy rains are in progress, storm clouds typically hide the flooding from satellite sensors. Even if flooding lingers after the clouds clear away, certain types of land cover (such as dense forests) can make floods notoriously difficult to spot.

Another way of seeing floods caused by rainfall is to look at the rainfall itself. The Earth Observatory sometimes publishes imagery from the Multisatellite Precipitation Analysis (MPA). MPA estimates rainfall by combining measurements from multiple satellites and calibrating them using rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite.

But as its name implies, TRMM focuses on the tropics. More specifically, TRMM specializes in picturing moderate to heavy rainfall over the tropical and subtropical regions. So we can visualize rainfall at relatively low latitudes, but places like the United Kingdom are too far north for this approach to work well.

GPM satellite constellation. Courtesy NASA Precipitation Measurement Missions.

Fortunately a solution is on the horizon—or more accurately, set to launch next year. The Global Precipitation Measurement (GPM) mission is an international collaboration spearheaded by NASA and the Japan Aerospace Exploration Agency (JAXA). Scheduled to launch in June 2014, the GPM Core Observatory will improve upon TRMM by extending observations to higher latitudes. And GPM won’t just focus on heavy rain; it will also observe light rain and snow, which comprise a significant portion of the precipitation at higher latitudes.

The NASA overview of GPM explains:

GPM will provide global precipitation measurements with improved accuracy, coverage, and dynamic range for studying precipitation characteristics. GPM is also expected to improve weather and precipitation forecasts through assimilation of instantaneous precipitation information.

So although the EO can’t visualize heavy rains in places like the UK now, that situation should change after the launch of GPM.

Wild Weather off Alaska

January 18th, 2013 by Mike Carlowicz

The weather seems to be getting weirder by the month. Perhaps we are more attuned to it now, in our hyper-connected, 24-hour-news-cycle world where the news from faraway places is almost as accessible as the news form our hometown. But the research and the models say that weather extremes should grow more extreme, and the observations seem to be living up to the predictions.

The latest case in point comes from the North Pacific and Alaska. This week, a huge storm system with hurricane-force winds lashed the Aleutian Islands in an unusual winter storm. See the video of the cyclone coming over the horizon, as viewed by a GOES satellite.

According to the Alaska Dispatch, winds at Shemya (site of a former U.S. Air Force base) reached 70 miles per hour and the U.S. Coast Guard was mobilizing to “safeguard the crab fleet and other fishing vessels in the area.” According to Climate Central, the storm generated open ocean waves approaching 62 feet and “had an air pressure reading of about 932 mb, roughly equivalent to a Category 4 hurricane, and more intense than Hurricane Sandy as that storm moved toward the New Jersey coastline in October.”

The storm was weakening as it moved northeast and was not expected to have a serious impact on the mainland of Alaska.

A Big Thank You To Our 100,000 Facebook Fans

January 12th, 2013 by Adam Voiland

On March 11, 2009, we posted our first image on Facebook, a spectacular view of ash billowing from Mount Etna (below). At the time, we had just a handful of friends on Facebook, and just a few of them shared it with theirs.

Fast forward three years…and tens of thousands of you have joined our Facebook community. We routinely receive dozens of comments and hundreds of you share nearly every image we post. On January 12, 2013, thanks to all of you, we hit a milestone we’ve been eying for months: 100,000 fans. The friends of these 100,000 fans, Facebook tells us, number over 34 million.

That’s an extraordinary number, but what’s even more notable is how much we’ve learned from all of you since that first post. You’ve told us what you like, what you don’t, and why. You’ve given us countless story ideas, and you have pushed us to keep digging and learning about images long after we hit the publish button. You’ve taught us—and each other—more than we could have imagined when we posted that first image.

So from all of us at the Earth Observatory, THANK YOU! To mark the occasion, we’ve pulled together (above) a few of our favorite craters, plus an atoll in French Polynesia that’s conveniently shaped like a 1. The craters include Pingualuit and Manicouagan in Canada, Lonar in India, Tenoumer in Mauritania, and Crater Lake in the United States. We’ll leave it to you to figure out which is which.

In the meantime, please keep your feedback coming. We love hearing from you, and it helps make our site better. And one last plea: please share this post with your friends, tell them to join our Facebook page, and let them know that we’d love to hear from them as well.

Arctic Report Card

December 10th, 2012 by Michon Scott

On December 5, 2012, the National Oceanic and Atmospheric Administration (NOAA) released its annual Arctic Report Card, covering late 2011 through late 2012. The report listed a number of significant events in a record-breaking and sometimes sobering year.

Photo courtesy NOAA ClimateWatch Magazine.

One of the biggest stories was the record-low sea ice extent in the Arctic Ocean. Arctic sea ice shrinks and grows every year, typically reaching its minimum in September. The last decade, however, has seen a series of below-normal extents, with new records set in 2002, 2005, 2007, and 2012. By mid-September 2012, Arctic sea ice had dropped to 3.41 million square kilometers (1.32 million square miles), which was significantly below the 2007 record of 4.17 million square kilometers (1.61 million square miles). (See Visualizing the 2012 Sea Ice Minimum for prior Earth Observatory coverage of this event.)

NOAA data for high latitudes during June indicated that snow cover extent has declined by 17.6 percent per decade—an even faster rate of decline than the sea ice extent. From June 2008 to June 2012, North America experienced three record-low snow cover extents, and Eurasia experienced five straight record lows.

The summer of 2012 also brought widespread melting on the Greenland Ice Sheet. An estimated 97 percent of the ice surface was melting at some point on July 11–12. July 2012 also brought an unusually high melt index—calculated by multiplying the number of days when melt occurred by the area that melted. Compared to the 1979–2012 average, the 2012 melt index was +2.4, nearly twice the previous melt index record set in 2010. (See Satellites Observe Widespread Melting Event on Greenland for prior Earth Observatory coverage of this event.)

The Greenland melting was linked to a drop in albedo—the amount of sunlight reflected back into space—on the ice sheet in 2012. A drop in albedo can set up a feedback loop; as the ice surface melts, it grows darker, absorbing more sunlight and melting more ice.

Other highlights of the 2012 Arctic Report Card include an increase in the length of the high-latitude growing season, record-high permafrost temperatures, a giant phytoplankton bloom under the ice in the Chukchi Sea, the threat of extinction to the Arctic fox, and severe weather events. (including a strong storm off Alaska and a strong summer storm over the Arctic.)

Reflecting on the year’s events, Mark Serreze, director of the National Snow and Ice Data Center, remarked: “The year 2012 was nature’s kick in the pants. Arctic sea ice and snow cover were at record lows and nearly the entire Greenland ice sheet saw surface melt. Climate change is here and Mother Nature is giving us a stern warning of bigger changes to come.”

For more information, see NOAA ClimateWatch Magazine, which offers report card highlights.

Dune Gallery

November 2nd, 2012 by Michon Scott

The November 2012 issue of National Geographic features an article, “Sailing the Dunes,” about aerial trips over sandy deserts. The author, George Steinmetz, has flown in light aircraft in high winds—a dangerous combination. Yet the same winds that make the flying so dangerous also sculpt some of the world’s most beautiful landscapes. Several of the places mentioned in the article have also been covered by the Earth Observatory. Here is a sampling of some of those places, plus some additional dune-rich landscapes.

The Sahara Desert spans northern Africa, covering about 9.4 million square kilometers (3.6 million square miles). Within the Sahara are multiple sand seas, or ergs — big, windswept landscapes of shifting sands. The ergs can be as photogenic as they are forbidding.

Issaouane Erg in Algeria holds multiple crescent-shaped (barchan) dunes and star dunes. Winds blowing mostly from one direction create barchan dunes while variable winds create star dunes. Low-angled sunlight highlights the varied dune shapes in this region. Story: Issaouane Erg, Algeria

Besides barchan dunes and star dunes, Issaouane Erg is also home to mega-dunes. Mega-dunes likely take hundreds of thousands of years to form, and may have started their formation when the Sahara—once a more hospitable place—began to dry. In between the big dunes, winds have swept sand away from the desert surface altogether, revealing gray-beige mud and salts. Story: Dune Types in the Issaouane Erg, Eastern Algeria

The flat areas between dunes are known as dune streets, and they are unmistakable in Algeria’s Erg Oriental. In between the streets, star dunes sit atop linear dunes. Story: Erg Oriental, Algeria

Nearly sand-free basins also separate complex dunes in the Marzuq Sand Sea of southwestern Libya. The big sand masses are known as “draa” dunes, Arabic for “arm.” Extending from some of the draa dunes are snakelike linear dunes. Story: Sand Dunes, Marzuq Sand Sea, Southwest Libya

Dunes form in arid conditions, but conditions can change. The manmade Toshka Lakes of Egypt flooded old dune landscapes. Depending on lake levels and the underlying topography, some dunes are completely flooded while the crests of others poke above the water surface. Story: Toshka Lakes, Egypt

Although it covers an area much smaller than the Sahara Desert, the Arabian Peninsula’s Empty Quarter, also known as Rub’ al Khali, holds half as much sand as the entire Sahara. Salt flats—sebkhas or sabkhas—separate the towering dunes. Story: Empty Quarter

Though it lacks the massive sand seas of the Sahara and the Arabian Peninsula, the United States sports some impressive dune fields of its own. White Sands National Monument holds gleaming white sands formed from gypsum. These brilliant white dunes occur at the northern edge of the Chihuahuan Desert, which extends across the U.S.-Mexico border. Story: White Sands National Monument

The Algodones Dunes of southeastern California lack the snowy look of White Sands, but make up for it by hosting a complex assortment of dune formations. Smaller dunes sit on top of giant crescent-shaped dunes. Wind does not act alone in shaping this landscape; water flows off the Cargo Muchacho Mountains to the east, making its way into the dune field and sustaining some plant life. Story: The Algodones Dunes

Some of the world’s most complex dune formations occur in the Badain Jaran Desert of Inner Mongolia. Small lakes dot flat areas in between dunes, which have been characterized as “complex reversing mega-dunes developed from compound barchanoid mega-dunes.” Story: Elevation Map of the Badain Jaran Desert

And sometimes a single desert can host completely different landscapes. Identified by satellite data as the hottest place on Earth, Iran’s Lut Desert contains two completely different landscapes. The central portion is home to wind-sculpted linear ridges known as yardangs. The southeastern part of the desert hosts dunes that soar to 300 meters (1,000 feet) alternating with salt pans. Story: Diverse Terrain of Iran’s Dasht-e Lut

Note that due to the angle of sunlight, some of these images produce an optical illusion known as relief inversion.