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Chilly Temperatures During t
…
| Title |
Chilly Temperatures During the Maunder Minimum |
| Description |
Many things can change temperatures on Earth: a volcano erupts, swathing the Earth with bright haze that blocks sunlight, and temperatures drop, greenhouse gases trap heat in the atmosphere, and temperatures climb. From 1650 to 1710, temperatures across much of the Northern Hemisphere plunged when the Sun entered a quiet phase now called the Maunder Minimum. During this period, very few sunspots appeared on the surface of the Sun, and the overall brightness of the Sun decreased slightly. Already in the midst of a colder-than-average period called the Little Ice Age, Europe and North America went into a deep freeze: alpine glaciers extended over valley farmland, sea ice crept south from the Arctic, and the famous canals in the Netherlands froze regularly—an event that is rare today. The impact of the solar minimum is clear in this image, which shows the temperature difference between 1680, a year at the center of the Maunder Minimum, and 1780, a year of normal solar activity, as calculated by a general circulation model. Deep blue across eastern and central North America and northern Eurasia illustrates where the drop in temperature was the greatest. Nearly all other land areas were also cooler in 1680, as indicated by the varying shades of blue. The few regions that appear to have been warmer in 1680 are Alaska and the eastern Pacific Ocean (left), the North Atlantic Ocean south of Greenland (left of center), and north of Iceland (top center). If energy from the Sun decreased only slightly, why did temperatures drop so severely in the Northern Hemisphere? Climate scientist Drew Shindell and colleagues at the NASA Goddard Institute for Space Studies tackled that question by combining temperature records gleaned from tree rings, ice cores, corals, and the few measurements recorded in the historical record, with an advanced computer model of the Earth's climate. The group first calculated the amount of energy coming from the Sun during the Maunder Minimum and entered the information into a general circulation model. The model is a mathematical representation of the way various Earth systems—ocean surface temperatures, different layers of the atmosphere, energy reflected and absorbed from land, and so forth—interact to produce the climate. When the model started with the decreased solar energy and returned temperatures that matched the paleoclimate record, Shindell and his colleagues knew that the model was showing how the Maunder Minimum could have caused the extreme drop in temperatures. The model showed that the drop in temperature was related to ozone [ http://earthobservatory.nasa.gov/Library/Ozone/ozone_2.html ], in the stratosphere, the layer of the atmosphere that is between 10 and 50 kilometers from the Earth's surface. Ozone is created when high-energy ultraviolet light from the Sun interacts with oxygen. During the Maunder Minimum, the Sun emitted less strong ultraviolet light, and so less ozone formed. The decrease in ozone affected planetary waves, the giant wiggles in the jet stream that we are used to seeing on television weather reports. The change to the planetary waves kicked the North Atlantic Oscillation (NAO) [ http://earthobservatory.nasa.gov/Study/NAO_200307/NAO.html ]—the balance between a permanent low-pressure system near Greenland and a permanent high-pressure system to its south—into a negative phase. When the NAO is negative, both pressure systems are relatively weak. Under these conditions, winter storms crossing the Atlantic generally head eastward toward Europe, which experiences a more severe winter. (When the NAO is positive, winter storms track farther north, making winters in Europe milder.) The model results, shown above, illustrate that the NAO was more negative on average during the Maunder Minimum, and Europe remained unusually cold. These results matched the paleoclimate record. By creating a model that could reproduce temperatures recorded in paleoclimate records, Shindell and colleagues reached a better understanding of how changes in the stratosphere influence weather patterns. With such an understanding, scientists are better poised to understand what factors could influence Earth's climate in the future. To read more about how ancient temperature records are used to improve climate models, see Paleoclimatology: Understanding the Past to Predict the Future, [ http://earthobservatory.nasa.gov/Study/Paleoclimatology_Understanding/paleoclimatology_understanding.html ] the final installment of a series of articles [ http://earthobservatory.nasa.gov/Study/Paleoclimatology/paleoclimatology_intro.html ] about paleoclimatology on the Earth Observatory. Map adapted from Shindell et al., 2001, copyright AAAS 2001. Terms and conditions of use for material copyright AAAS: Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or in part, without prior written permission from the publisher. |
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New Measurements of Arctic O
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| Title |
New Measurements of Arctic Ozone |
| Description |
The winter of 2004-2005 saw the second highest chemical ozone destruction ever observed over the Arctic. Polar ozone is destoyed when chlorine, cold temperatures, and sunlight mix in the atmosphere 8-50 kilometers above the Earth's surface. Since ozone shields the Earth from ultraviolet light, the high-energy light that causes sunburns and is associated with skin cancers, low ozone levels could threaten human health. Ultraviolet levels remained near normal through the winter, however, because unusual weather conditions brought ozone from the Earth's ozone-rich mid-latitudes to the pole to fill in the gaps left by the extreme ozone depletion. These images show the fluctuations in ozone during the Arctic winter of 2005. The top two images show the average total column ozone over the Arctic during the months of January and March, 2005, and the lower image shows total column ozone on a single day, March 11, 2005. The images are based on data collected by the Ozone Monitoring Instrument [ http://www.knmi.nl/omi/publ-en/news/index.html ] (OMI) aboard NASA's Aura [ http://aura.gsfc.nasa.gov/ ] satellite. During this time period, the Microwave Limb Sounder, another instrument on the Aura satellite, measured 50 percent ozone loss, the second-highest level ever observed behind the 60 percent loss measured in 1999-2000. Despite this, the lowest total column ozone values in polar regions are slightly higher in March than in January, on average, as evidenced by the broad splashes of red that represent high ozone levels. Stratospheric winds carried the ozone north into the Arctic, compensating for the significant chemical loss, so that no blue or purple holes representing low ozone levels appear in the March image. Black circles over the North pole show where OMI did not collect data. On a single day, March 11, 2005, ozone was distributed far more unevenly, with dark red, almost black areas of high ozone over the Aleutian Islands, Asia, and Europe, and a pale blue thin spot over Iceland and Greenland. This reveals that even though ozone values appeared to be near normal on average throughout March, some regions experienced much lower ozone levels—and therefore, a greater exposure to UV light—on an individual day. For more information and images, see "NASA Spacecraft Measures Unusual 2005 Arctic Ozone Conditions" [ http://www.nasa.gov/vision/earth/lookingatearth/aura-060205.html ] on the NASA portal. Image courtesy NASA/JPL/Agency for Aerospace Programs (Netherlands)/Finnish Meteorological Institute |
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North Atlantic Bloom
| Title |
North Atlantic Bloom |
| Description |
Reminiscent of the distinctive swirls in a Van Gogh painting, millions of microscopic plants color the waters of the North Atlantic with strokes of blue, turquoise, green, and brown. Fed by nutrients that have built up during the winter and the long, sunlit days of late spring and early summer, the cool waters of the North Atlantic come alive every year with a vivid display of color. The microscopic plants, called phytoplankton, that give the water this color are the base of the marine food chain. Some species of phytoplankton are coated with scales of calcium (chalk), which turn the water electric blue. Chlorophyll and other light-capturing pigments in others give the water a deep green hue. The proliferation of many different species in various stages of growth and decay provides many nuances of color in this concentrated bloom. The bloom stretches across hundreds of kilometers, well beyond the edges of this photo-like image, captured on June 23, 2007, by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) flying aboard NASA's Aqua [ http://aqua.nasa.gov/ ] satellite. The upper left edge of the image is bounded by Greenland. Iceland is in the upper right. Plumes of dust [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14345 ] are blowing off the island, probably adding nutrients to the surface waters to its south. NASA image courtesy Norman Kuring, Ocean Color Group at NASA Goddard Space Flight Center |
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Ring of Fire Revisited
| Title |
Ring of Fire Revisited |
| Explanation |
Early on Saturday [ http://skyandtelescope.com/observing/objects/eclipses/ article_924_1.asp ], May 31 (UT) the new Moon will once again slide across the Sun's fiery disk, and once again [ http://antwrp.gsfc.nasa.gov/apod/ap020610.html ] an annular solar eclipse [ http://sunearth.gsfc.nasa.gov/eclipse/ASE2003/ ASE2003.html ] will be the result -- since the Moon's apparent diameter [ http://www.rc-astro.com/composite/sun_moon.htm ] will be a little too small to completely cover the Sun [ http://www.earthview.com/tutorial/tutorial.htm ]. But this time celestial geometry [ http://members.aol.com/atsinclair/ecl2003.htm ] has conspired to produce a broad D-shaped region [ http://sunearth.gsfc.nasa.gov/eclipse/ASE2003/ASE2003gif/ ASE2003-1b.GIF ] for viewing the annular phase that extends into the far northern hemisphere, rather than creating a thin track racing across land and sea. The characteristic ring of fire will be visible from northern Scotland, Iceland, and parts of Greenland. Otherwise a partial eclipse will be more widely visible as across Europe, along with parts of Asia and North America, the Moon will appear to take a "bite" out of the Sun. While the northerly observers might certainly expect a dramatic view [ http://www.astrosurf.com/alphaweb/10mai94/ ], it will probably not look quite like this one [ http://www.skyscapes.com/Shadows%20in%20the%20Sky/ RingFire.htm ], recorded with a foreground of palm trees during a 1992 annular eclipse. Want to watch Saturday's eclipse on the web? Check out the planned webcasts from Astronet [ http://www.xs4all.nl/~carlkop/zoneclips/eclipse.html ]. |
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North Atlantic Bloom: Natura
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nasa, nasanaturalhazards
Reminiscent of the distincti
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IcelandBloom_AMO_2007174
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2007-06-23 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
IcelandBloom_AMO_2007174 |
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North Atlantic Bloom: Image
…
nasa, nasaimageofthedaygalle
…
Reminiscent of the distincti
…
ge_07830
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2007-06-23 |
| creator |
NASA -- NASA image courtesy Norman Kuring, Ocean Color Group at NASA Goddard Space Flight Center |
| identifier |
ge_07830 |
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Chilly Temperatures During t
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nasa, nasaimageofthedaygalle
…
Many things can change tempe
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maunder_minimum_temperature
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2006-08-10 |
| creator |
NASA -- Map adapted from Shindell et al., 2001, copyright AAAS 2001. Terms and conditions of use for material copyright AAAS: Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or in part, without prior written permission from the publisher. |
| identifier |
maunder_minimum_temperature |
|
Iceland: Image of the Day
nasa, nasaimageofthedaygalle
…
True to its name, Iceland is
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image02022004
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2004-01-28 |
| creator |
NASA -- Image courtesy Jeff Schmaltz, rapidfire.sci.gsfc.nasa.gov/ MODIS Land Rapid Response Team at NASA GSFC |
| identifier |
image02022004 |
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Changes in Arctic Ice : Imag
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nasa, nasaimageofthedaygalle
…
Largely natural ''ups and do
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arctic_ice_icelandic_low
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2001 |
| creator |
NASA -- Image courtesy Claire Parkinson and Nick Digirolamo, NASA Goddard Space Flight Center |
| identifier |
arctic_ice_icelandic_low |
|
| General Description |
STS-85 Shuttle Mission Imagery |
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