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[气候监测] 2012年北极海冰关注贴 北极海冰最低值刷新!

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发表于 2012-7-8 14:58 | 显示全部楼层 |阅读模式
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北极波弗特海上融化的冰。(自美国国家海洋和大气管理局)


近年来,北极海冰经历了前所未有的大规模融化。虽然目前距离海冰覆盖面积达到年度最低值还有几个月时间,但据趣味科学网报道,今年夏天很可能还会持续这个趋势,带来罕见的大面积无冰水域。
  
美国国家冰雪数据中心对卫星观测数据的分析结果显示,春季的绝大部分时间里,海冰面积一直在1979年至2000年平均值确立的基线附近徘徊;到了6月,冰面更是降到了极低的程度。
  
美国国家冰雪数据中心的科学家沃尔特?迈耶(Walt Meier)说:“这无疑预示着一个少冰的一年,但是否意味着将低于2007年(最低纪录出现在9月),要做出判断还为时尚早。”
  
迈耶表示,海冰经历着季节性的周期变化,冬季在北极水域上蔓延,到了温暖的夏季就会回退。从历史上来看,为海象和北极熊提供了重要栖息地的海冰,其覆盖面积最低值出现在9月的第一周到大约第三周结束的这段时间内。
  
自1979年开始有持续的记录数据以来,最近几年都创下了海冰覆盖面积低值纪录,科学家将之归咎于多重自然气候波动因素的综合影响,风的模式、通过白令海峡的水流量、天空的云层、降雪量,还有今年夏天烟尘的存在,都可能影响到海冰消融的速度。
  
迈耶说:“在北冰洋内以及沿海岸线很多通常是被冰层覆盖的地方变成了开放的水面。每年这个时候都很重要,因为我们正在接近夏至日,在北半球太阳高度将达到最大值。”
  
虽然白色的冰层将大部分来自太阳的能量反射回太空,但深色的水面会吸收更多的能量,并且会持续不断地吸收,即使北极地区的太阳照射在逐渐减少。此外,地轴的倾斜意味着,北极圈范围内在夏至这一天会出现极昼,纬度越高的地方极昼越长。因此,在这段时间内,暴露在阳光下的深色的水面越多,它吸收的热量也就越多。
  
随着夏季的推移,太阳在北极上空照射的时间越来越少,但水中储存的热量仍然会让海冰继续融化。海冰覆盖面积低同时也是冰层较薄的信号,这样的冰层在夏季更容易消融。迈耶说,最近的观测显示,有一定年头的较厚的海冰出现了显著的损失。科学家认为,人类温室气体排放造成的全球变暖是近年来海冰覆盖面积达到空前低值的部分原因。
  
事实上,北极海冰覆盖面积的重要性体现在多个方面。冰面覆盖率下降给北极的野生动物带来了难题。有证据表明,更多开放的水面会迫使北极熊长距离游泳,并造成大批海象拥挤在海滩上。
  
按照美国国家冰雪数据中心的排行榜,2007年9月16日的海冰覆盖面积最低,2011年9月9日为第二低。而德国布莱梅大学的研究小组使用不同的卫星数据得出了另外的结论,他们认为2011年9月8日才是最低纪录的开创日。

原文:http://www.chinadaily.com.cn/hqg ... ontent_6245447.html

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 楼主| 发表于 2012-7-8 15:12 | 显示全部楼层

求翻译

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Sea ice retreat in June is typical, as the summer solstice approaches in the Northern Hemisphere with long hours of sunlight to warm the Arctic and melt snow and sea ice. However, the first half of June 2012 brought unusually rapid ice loss.

One area of rapid ice retreat was the Beaufort Sea, north of Alaska. By mid-June, the open-water area off the coast had expanded substantially and snow had melted on land. The rapid melt north of Alaska was part of a larger phenomenon. According to the National Snow and Ice Data Center (NSIDC), sea ice across the entire Arctic reached record-low levels for this time of year, slightly below the previous record set in June 2010. It was also lower than the extent in June 2007, the same year when Arctic sea ice reached its lowest extent ever recorded by satellite in September.

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In the first half of June 2012, the Beaufort Sea was a “hotspot” of rapid retreat, driven by a high-pressure pattern over the region that kept skies clear at the very time of year when sunlight lasts the longest. In addition, larger-scale climate patterns in early June 2012 favored ice retreat along the coastlines of Alaska and Siberia. As of June 18, temperatures were above freezing over much of the sea ice in the Arctic, and snow had melted earlier than normal, leading to warming on land.

NSIDC’s report from June 19, 2012 points that recent ice loss rates have been 100,000 to 150,000 square kilometers (38,600 to 57,900 square miles) per day, which is more than double the climatological rate.
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The early onset of the spring melt and the sunny skies around the solstice increased the likelihood of heightened melt rates throughout the rest of the summer, largely by reducing albedo: the proportion of solar energy reflected back into space. If an object reflects all the energy it receives, it has an albedo of 1.0. Sea ice has high albedo because of its bright appearance. But when it starts to melt, its albedo drops from roughly 0.9 to 0.7, causing the ice to absorb more energy. Increased energy absorption leads to increased melt, which exposes ocean water. Thanks to its dark appearance, ocean water has an albedo of less than 0.1. Long, sunny days pour energy into the water, and it retains the heat throughout the summer. In September, when the Sun is low on the horizon, the heated ocean water continues melting sea ice.
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NASA. NOAA. USGS. NSIDC. ESA. National Geographic. Discovery.
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发表于 2012-7-8 15:41 | 显示全部楼层
和正在发展的厄尔尼诺有关系吗?
潜伏中的价值投资者
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发表于 2012-7-8 16:06 | 显示全部楼层
我国北方的降水量要增加了
Chinese Engineers Lives Matter中国工程师的命也是命
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发表于 2012-7-9 14:33 | 显示全部楼层

回 invensys 的帖子

invensys:
Sea ice retreat in June is typical, as the summer solstice approaches in the Northern Hemisphere with long hours of sunlight to warm the Arctic and melt snow and sea ice. However, the first half of June 2012 brought unusually rapid ice loss .. (2012-07-08 15:12)
随着北半球夏至的到来,北极冰雪开始加速融化,每年的6月都是北极快速融冰的开始。但据美国国家冰雪数据中心(NSIDC)报道,2012年6月上半月,北极海冰融化异常迅速。

  美国阿拉斯加州北部的波弗特海是海冰快速融化的区域之一。上面这两幅照片是美国宇航局Terra卫星上的中分辨率成像光谱仪(MODIS)分别于​​2012年5月13日(上)和6月16日(下)拍下的。在照片中可以看到,到6月中旬,波弗特海沿岸的无冰海面已大幅扩大,岸上的积雪也开始融化。

  2012年6月的上半月,波弗​​特海海冰迅速融化的原因是该地区受到高压气候的控制。在这种气候模式之下,日照时间最长,天气晴朗。此外,2012年6月上旬,更大规模的气候模式也加速了阿拉斯加和西伯利亚沿岸的海冰撤退。在6月18日之前,北极大部分地区气温就已经达到零度以上,海冰比正常情况下提前融化。

  美国国家冰雪数据中心2012年6月19日报道:“最近的海冰损失率为每天10万至15万平方公​​里(美国伊利诺伊州面积大约为15平方公里),达到平均值的两倍以上。”

  融冰时间提前和夏至前后的温暖天气导致反射率(海冰反射太阳能的比率)减少,从而增加了整个夏天融冰加速的可能性。如果一个物体将它接收到的所有能量都反射出去,它的反射率为1.0。由于海冰表面为亮白色,海冰具有很高的反射率。

  但是,当海冰开始融化时,它的反射率会下降至0.9至0.7,导致海冰吸收更多的太阳能量。增加的能量使海冰加速融化,暴露出更多的海面。由于海面的颜色较深,其反照率小于0.1。温暖的天气使海水吸收并储存了更多的能量。到9月阳光减弱且日照时间变短时,储存着相当热量的海水会继续融化海冰。
帖子中涉及地图来源广泛,图中所涉及的行政区域以中国官方认定的为准。
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发表于 2012-7-9 14:43 | 显示全部楼层
Rapid sea ice retreat in June


July 5, 2012

Arctic sea ice extent declined quickly in June, setting record daily lows for a brief period in the middle of the month. Strong ice loss in the Kara, Bering, and Beaufort seas, and Hudson and Baffin bays, led the overall retreat. Northern Hemisphere snow extent was unusually low in May and June, continuing a pattern of rapid spring snow melt seen in the past six years.


Figure 1. Arctic sea ice extent for June 2012 was 10.97 million square kilometers (4.24 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image
Daily data files
Overview of conditions
Arctic sea ice extent for June 2012 averaged 10.97 million square kilometers (4.24 million square miles). This was 1.18 million square kilometers (456,000 square miles) below the 1979 to 2000 average extent. The last three Junes (2010-2012) are the three lowest in the satellite record. June 2012 ice extent was 140,000 square kilometers (54,000 square miles) above the 2010 record low. Ice losses were notable in the Kara Sea, and in the Beaufort Sea, where a large polynya has formed. Retreat of ice in the Hudson and Baffin bays also contributed to the low June 2012 extent. The only area of the Arctic where sea ice extent is currently above average is along the eastern Greenland coast.
The ice extent recorded for 30 June 2012 of 9.59 million square kilometers (3.70 million square miles) would not normally be expected until July 21, based on 1979-2000 averages. This puts extent decline three weeks ahead of schedule.


Figure 2. The graph above shows Arctic sea ice extent as of July 2, 2012, along with daily ice extent data for the previous five years. 2012 is shown in blue, 2011 in orange, 2010 in pink, 2009 in navy, 2008 in purple, and 2007 in green. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image
Daily data files
Conditions in context
In June, the Arctic lost a total of 2.86 million square kilometers (1.10 million square miles) of ice. This is the largest June ice loss in the satellite record. Similar to May, the month was characterized by a period of especially rapid ice loss (discussed in the mid-month entry, June 19th) followed by a period of slower loss. Warm conditions prevailed over most of the Arctic; temperatures at the 925 hPa level (about 3000 feet above the ocean surface) were typically 1 to 4 degrees Celsius (1.8 to 7.2 degrees Fahrenheit) above the 1981 to 2010 average, and as much as 7 to 9 degrees Celsius (12.6 to 16.2 degrees Fahrenheit) above average over northern Eurasia and near southern Baffin Bay. Weather patterns over the Arctic Ocean varied substantially through the month.


Figure 3. Monthly June ice extent for 1979 to 2012 shows a decline of 3.7% per decade.

Credit: National Snow and Ice Data Center
High-resolution image
帖子中涉及地图来源广泛,图中所涉及的行政区域以中国官方认定的为准。
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 楼主| 发表于 2012-7-25 12:36 | 显示全部楼层

97% of the Greenland’s ice sheet surface melted in mid-July

Greenland’s surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations in period of merely few days this month. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists. Satellite data reveals an estimated 97% of the ice sheet surface thawed at some point in mid-July. Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story according to Tom Wagner, NASA’s cryosphere program manager in Washington. This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland’s weather since the end of May with each successive ridge stronger than the previous one.

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Even the area around Summit Station in central Greenland, which at about 3,2 km (2 miles) above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores analyzed by Kaitlin Keegan at Dartmouth College in Hanover, N.H. A National Oceanic and Atmospheric Administration weather station at Summit confirmed air temperatures hovered above or within a degree of freezing for several hours July 11-12. However, ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time according to Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. But she also points that if we continue to observe melting events like this in upcoming years, it will be worrisome.

About half of the surface of Greenland’s ice sheet melts every summer. It is natural process. At high elevations, most of that melt water quickly refreezes in place. Some of the melt water is retained by the ice sheet near the coast and the rest is lost to the ocean. Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

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In July 2012, a massive ice island broke free of the Petermann Glacier in northwestern Greenland. On July 16, the giant iceberg could be seen drifting down the fjord, away from the floating ice tongue from which it calved. Similar surface cracks appear on both the Petermann Glacier and the newly formed ice island. Ted Scambos of the National Snow and Ice Data Center observed melt ponds on the iceberg surface, but stated that the Petermann calving was likely associated with ocean currents rather than surface melt.

Nearly two years ago in July 2010, another large iceberg calved from the Petermann Glacier. That iceberg was estimated at roughly 251 square kilometers (97 square miles). The 2012 iceberg is estimated to be about half as big. This latest calving occurred farther upstream on the Petermann, but nevertheless occurred along a rift that appeared in satellite imagery in 2001.

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SATELLITE DATA

At first, preliminary data puzzled researchers and scientist. Son Nghiem of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., was analyzing radar data from the Indian Space Research Organisation’s (ISRO) Oceansat-2 satellite last week when he noticed that most of Greenland appeared to have undergone surface melting on July 12. This was so extraordinary event that at firsthe questioned the result: was this real or was it due to a data error? Nghiem then consulted with Dorothy Hall at NASA’s Goddard Space Flight Center in Greenbelt, Md. (Hall studies the surface temperature of Greenland using the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites) She confirmed that MODIS showed unusually high temperatures and that melt was extensive over the ice sheet surface. Thomas Mote, a climatologist at the University of Georgia, Athens, Ga; and Marco Tedesco of City University of New York also confirmed the melt seen by Oceansat-2 and MODIS with passive-microwave satellite data from the Special Sensor Microwave Imager/Sounder on a U.S. Air Force meteorological satellite.
NASA. NOAA. USGS. NSIDC. ESA. National Geographic. Discovery.
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发表于 2012-7-25 19:55 | 显示全部楼层
http://nsidc.org/arcticseaicenews/IMAGES
Sea ice continues to track at low levels
海冰继续维持在较低水平
July 24, 2012

Arctic sea ice continued to track at levels far below average through the middle of July, with open water in the Kara and Barents seas reaching as far north as typically seen during September. Melt onset began earlier than normal throughout most of the Arctic.
七月中旬的北极海冰持续远低于平均水平,在喀拉海和巴伦支海的打开水域到达遥远的北方,该水域通常在9月才能达到这个水平。整个北极冰开始融化时间比正常情况提前。


Figure 1. Arctic sea ice extent for July 23, 2012 was 7.32 million square kilometers (2.82 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole.
图1。2012年7月23日北极海冰面积为732万平方公里(282万平方英里)。洋红色线条显示1979〜2000年该月的中位程度。黑色十字指示地理北极。
Sea Ice Index data. About the data Credit: National Snow and Ice Data Center
海冰指数数据有关资料来源:国家冰雪数据中心
High-resolution image

Overview of conditions
条件概述

As of July 23, 2012, sea ice extent was 7.32 million square kilometers (2.82 million square miles). On the same day last year, ice extent was 7.22 million square kilometers (2.78 million square miles), the previous record low for this day.Arctic sea ice extent continued to track at very low levels, setting daily record lows for the satellite era for a few days in early July. Extent is especially low in the Barents, Kara, and Laptev seas. In the Barents and Kara seas, the area of open water extends to the north coasts of Franz Josef Land and Severnaya Zemlya, as far north as typically seen during September, the end of the summer melt season. Polynyas in the Beaufort and East Siberian seas continued to expand during the first half of July. By sharp contrast, ice extent in the Chukchi Sea remains near normal levels. In this region the ice has retreated back to the edge of the multiyear ice cover. Ice cover in the East Greenland Sea, while of generally low concentration, remains slightly more extensive than normal.
截至2012年7月23日,海冰面积为732万平方公里(282万平方英里)。稍高于去年同一天722万平方公里(278万平方英里)的海冰面积。北极海冰持续维持在非常低的水平,七月初几天每天创建卫星时代的纪录低点。喀拉海、巴伦支海和拉普捷夫海海冰面积尤其低。在巴伦支海和喀拉海,打开的水域延伸到法兰士约瑟夫地以北沿海和北地群岛,远北部通常在九月才看到的夏季融化季节结束。在波弗特海和东西伯利亚海域的冰穴,七月上旬继续扩大。以此形成鲜明对比的是,楚科奇海的冰程度仍接近正常水平,在这一地区的冰向后退到多年冰盖的边缘。而东格陵兰海的普遍冰盖含量低,仍略多于正常。

Figure 2. The graph above shows Arctic sea ice extent as of July 23, 2012, along with daily ice extent data for the previous four years. 2012 is shown in blue, 2011 in orange, 2010 in pink, 2009 in navy, 2008 in purple, and 2007 in green. The gray area around the average line shows the two standard deviation range of the data.
图2。上述图表显示2012年7月23日的北极海冰程度与过去四年每天冰程度的数据。 2012年蓝色显示,2011年橙色,2010年粉红,2009年深蓝,2008年紫色,2007年绿色。平均线周围的灰色区域表示数据的两个标准偏差范围。

Sea Ice Index data.Credit: National Snow and Ice Data Center
海冰指数数据来源:国家冰雪数据中心
High-resolution image

Conditions in context
背景条件

The first part of July was once again dominated by high sea level pressure over the Beaufort Sea, combined with low sea level pressure over Siberia and Alaska. As discussed in last month’s post, this pressure pattern tends to promote above-average temperatures and enhances ice transport out of the Arctic through Fram Strait. Beginning July 11th, the pressure pattern changed as cyclones moved into the central Arctic Ocean, bringing in cooler temperatures and helping to slow ice loss. Air temperatures at the 925 hPa level (about 3000 feet) in the central Arctic and the Beaufort Sea were 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above normal as averaged from July 1 to July 14. In the Beaufort and Chukchi seas, the sea ice has retreated to the edge of the multiyear ice cover. As a result of the anomalously high air temperatures, melt over the multiyear ice cover is extensive and ice concentrations are low. Anomalously low air temperatures for that period were found in the Barents, Kara, and East Greenland seas (1 to 3 degrees Celsius, or 2 to 6 degrees Fahrenheit, below the 1981 to 2010 climatology).
7月的第一部分,波弗特海再次被海平面高气压控制,与西伯利亚和阿拉斯加上的海平面低压相结合。正如在上个月的文章所讨论的,这种压力模式的趋向促进了高于平均气温的条件和增强了北极冰经过弗拉姆海峡的传出。 7月11日开始,压力模式发生了变化,由于气旋移进北冰洋中部,带来更冷的温度并帮助冰的损失减缓。从7月1日至7月14日,北极中部和波弗特海在925百帕层面(约3000英尺)的气温高于正常平均1-4摄氏度(2至7华氏度)。波弗特海和楚科奇海的海冰已退至多年的冰盖边缘。由于气温异常高的原因,多年的冰盖融化广泛和海冰密集度低。这期间在巴伦支海,喀拉,格陵兰岛东部海域发现异常低的气温(低于1981年至2010年气候1至3摄氏度,或2至6华氏度,)。

Figure 3. The map of melt onset (top) shows that melting began earlier than normal throughout most of the Arctic. The chart of melt onset dates (bottom) shows that melt in the Kara and Barents seas began more than two weeks earlier than normal. Melt onset in the Laptev Sea was the earliest seen in the satellite record.
图3。融化起始的地图(上)显示,整个北极的融化开始时间比正常情况提前。融化起始日期(底部)图表显示,喀拉海和巴伦支海冰融化开始时间比正常情况提前了两个多星期。在卫星记录中看到拉普捷夫海冰融化起始最早。

Credit: National Snow and Ice Data Center, data from Thorsten Markus and Jeffrey Miller/NASA Goddard Space Flight Center
来源:国家冰雪数据中心,数据来自美国宇航局戈达德太空飞行中心的Thorsten Markus 和Jeffrey Miller
High-resolution images: Figure 3 (top), Figure 3 (bottom)

Early melt onset
融化起始初期

The timing of seasonal melt onset, which can be estimated from satellite passive microwave data, plays an important role in the amount of ice that melts each summer. Unusually early melt onset means an early reduction in the surface albedo, allowing for more solar heating of the ice, which in turn allows melt ponds and open water areas to develop earlier in the melt season. In 2012, melt began earlier than normal (as compared to averages for the period 1979 to 2000) throughout most of the Arctic, the exceptions being the Bering Sea and the East Greenland Sea. Melt in the Kara and Barents seas began more than two weeks earlier than normal. Melt onset for the Laptev Sea region as a whole started on June 1 and was the earliest seen in the satellite record. Melt began 12 and 9 days earlier than normal averaged over the Beaufort and Chukchi seas, respectively.
从卫星无源微波数据可以估计季节性融化起始时间,起始的时间在每年夏天融化的冰量里起着重要的作用。早期融化起始异常意味着早期的地表反射率降低,让更多的太阳热能加热冰,这反过来又使融化池和打开水域在融化季节的早期发展。2012年,大部分北极的融化开始比正常情况提前(相比1979年至2000年期间平均),除了白令海和东格陵兰海。喀拉海和巴伦支海开始融化比正常情况提前了两个多星期。整个拉普捷夫海地区融化在6月1日开始,并在卫星记录中看到的起始最早。波弗特和楚科奇海熔融开始时间,分别比正常平均情况提前12日和9日。

Figure 4. This composite image from the SSMIS instrument obtained on July 23, 2012 shows areas of low ice concentration in the Beaufort and Chukchi seas, the Canadian Archipelago, the East Greenland Sea, and north of Siberia. Purple indicates areas of high sea ice concentration, while yellow and red indicate lower ice concentration. Blue shows open water and green shows land.
图4。从2012年7月23日SSMIS仪器获得的复合图像显示波弗特海和楚科奇海、加拿大北极群岛、格陵兰岛东部海域和北部西伯利亚冰含量较低,紫色表示海冰含量高的地区,而黄色和红色表示冰含量低的地区。蓝色表示打开水域以及绿色表示陆地。

Credit: National Snow and Ice Data Center courtesy IUP Bremen
来源:国家冰雪数据中心IUP Bremen提供
High-resolution image

Low ice concentrations
海冰密集度低

NSIDC uses satellite data from the Special Sensor Microwave Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) instruments, in part because they provide the longest consistent time series of data. However, more recent sensors such as the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) provide a more detailed perspective. In particular, we can examine ice concentration, which tells us how much ice is in a pixel, providing information on how vulnerable the ice may be to summer melting.In October 2011, the AMSR-E instrument on board the NASA Aqua satellite ceased operation, dealing a blow to the science community. This is because its higher spatial resolution and advanced technology provided detailed ice information to complement the long-term record of the Special Sensor Microwave Imager/Sounder (SSMIS) instrument. However, the Japanese Aerospace Exploration Agency (JAXA) successfully launched a new satellite called Shizuku, or Global Change Observation Mission 1st-Water (GCOM-W1), on 18 May 2012. The Shizuku carries a new Advanced Microwave Scanning Radiometer (AMSR2) instrument, a sensor similar to AMSR-E. As soon as calibration and validation of AMSR2 are complete, the University of Bremen will once again produce maps of sea ice concentration at a fairly high resolution (about 6 kilometers).In the meantime, the University of Bremen offers sea ice concentration maps from the lower-resolution SSMIS. The July 23 chart shows areas of low sea ice concentration in the Beaufort and Chukchi seas, the Canadian Archipelago, the East Greenland Sea, and north of Siberia. In the Beaufort and Chukchi seas, low ice concentrations and polynyas are found over areas of multiyear sea ice, where open water areas have developed between individual multiyear ice floes and significant ponding on the ice is observed. Low ice concentrations mean a low surface albedo, allowing for more of the sun’s energy to be absorbed, melting even more sea ice. This makes the multiyear ice in the Beaufort and Chukchi seas vulnerable to melting out this summer.
NSIDC使用的卫星数据来自特别传感器微波成像仪(SSM / I)和特别传感器微波成像仪/测深仪(SSMIS)仪器,部分是因为提供了一致时间最长的数据系列。不过,最近的传感器,例如地球观测系统(AMSR-E的)的高级微波扫描辐射计提供更详细的视角。特别是我们可以检查冰含量,它告诉我们多少冰是一个像素,提供有多少脆弱冰可能在夏天融化的信息。2011年10月,美国宇航局Aqua卫星上的AMSR-E的仪器停止运作,给科学界以当头一棒。这是因为其有较高的空间分辨率和先进的技术,提供详细的冰信息来补充特别传感器微波成像仪/测深仪(SSMIS)仪器长期的记录。然而,日本宇宙航空研究开发机构(JAXA)2012年5月18日成功推出一个新的卫星称为Shizuku,或全球变化观察团1ST-水(GCOM-W1),Shizuku承载一种新高级微波扫描辐射计(AMSR2)仪器,类似于AMSR-E传感器。一旦AMSR2的校准和验证完整,不来梅大学将再次制作相当高分辨率(约6公里)的海冰含量地图。在此期间,不来梅大学提供海冰含量分辨率较低的SSMIS地图。7月23日图表显示在波弗特海和楚科奇海,加拿大北极群岛,格陵兰岛东部海域,北部西伯利亚地区的海冰含量低。在波弗特海和楚科奇海的海冰低密集度和冰穴发现超过多年海冰区,在打开水域观察到多年个体浮冰和显著积水之间的冰有发展。海冰密集度低是指地表反射率低,让更多的太阳的能量被吸收,海冰更易融化,这使得今年夏天波弗特海和楚科奇海的多年冰块容易融化。
帖子中涉及地图来源广泛,图中所涉及的行政区域以中国官方认定的为准。
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发表于 2012-7-27 06:56 | 显示全部楼层
Flooding in Kangerlussuaq, Greenland
格陵兰岛Kangerlussuaq的洪水
July 27, 2012


acquired May 31, 2012
2012年5月31日获得的图像

acquired July 12, 2012
2012年7月12日获得的图像

acquired May 31, 2012 download large image (4 MB, JPEG, 4362x2908)
acquired July 12, 2012 download large image (3 MB, JPEG, 4362x2908)
acquired July 25, 2012 download large image (3 MB, JPEG, 4362x2908)
acquired May 31 - July 25, 2012 download Google Earth file (KML)

View Image Comparison View Both Images
Greenland has been a recurring source of headlines in July 2012, with the calving of a new iceberg off the Petermann Glacier and surface melting across nearly all of the Greenland Ice Sheet. Now there are new satellite images of flooding in Kangerlussuaq, a key air transportation hub.
2012年7月,随着彼得曼冰川崩解产生新冰山以及格陵兰几乎所有的冰盖表面融化,格陵兰岛已经成为新闻经常关注的焦点。现在的新卫星图像显示格陵兰重要的航空运输枢纽Kangerlussuaq,又发生了洪水。

Located in southwestern Greenland roughly 125 kilometers (75 miles) from the coast, Kangerlussuaq, or Kanger, hosts one of the island’s busiest commercial airports and is a frequent departure point for scientific research flights, including the NASA IceBridge program. Near the airport, the Watson River flows through town.The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite observed the flooded river on July 12, 2012 (bottom). For comparison, the top image shows the same area on May 31, 2012. On July 12, river levels are discernibly higher throughout the image; downstream from Kangerlussuaq, braided channels have merged into a single water body. In both images, the river’s light blue-green-gray color likely results from glacial flour suspended in the water. (A third image—attached as a 3MB download—shows the river levels receding again by July 25.)
Kangerlussuaq或Kanger,位于格陵兰西南海岸大约125公里(75英里),担负着岛上最繁忙的商业机场之一和经常科研试飞的出发地,包括美国宇航局的IceBridge计划。美国国家航空航天局地球观测-1(EO-1)卫星上的先进陆地成像仪(ALI)于2012年7月12日,观测到机场附近流经镇的Watson河(下)洪水。与2012年05月31日同一地区的图片显示作比较, 7月12日的图像能辨别出河流水位更高;Kangerlussuaq下游,辫状渠道已合并成单一的水域。这两个图像中河流的淡蓝色、灰绿色,有可能是冰川粉悬浮在水中的结果。 (第三个图像附上链接,下载(3MB)-显示7月25日该河流水位再次回落。)

A bridge spans the river at a narrow point southeast of the airport, and allegedly dates from the 1950s. Jason Box of the Byrd Polar Research Center at Ohio State University remarked: “In previous high-melt years, I suspected the bridge’s years were numbered.” Having recently returned from a trip to Greenland, Box noted an increase in the intensity of spring and summer melt over the past dozen years.”Water rises every year, but I\'ve never before observed it at this level of discharge,” said Richard Forster, a University of Utah professor who has done extensive fieldwork in Greenland. ”It was also about two weeks prior to the normal seasonal peak. It was most likely due to melt on the ice sheet—rather than an ice-dammed lake bursting or glacial lake drainage—as the high discharge was maintained for so long.”
桥横跨在机场东南的河流窄点上,据说建于20世纪50年代。俄亥俄州立大学Byrd极地研究中心的Jason Box说:“在以前的高融年,我猜想过桥的岁数,我最近从格陵兰岛之旅返回,Box指出在过去的十几年春季、夏季融化的强度上升。“每年水涨上升,但我以前从未观察到这个流量水平,”犹他州大学教授Richard Forster在格陵兰岛做了广泛的实地考察后说,“这也是大约两周之前到正常的季节高峰。高流量维持这么久,这最有可能是由于冰盖的融化,而不是冰堰塞湖爆裂或冰川湖下泄。”

“It has been a phenomenal year for melt” added Ted Scambos, lead scientist at the National Snow and Ice Data Center. “Even though melt water mostly refroze in place in the upper part of the Greenland Ice Sheet, lower down the melt runs off the ice sheet into rivers and creeks and into the ocean.”Around the same time that ALI captured the July 12 image, observers on the ground marveled at the high water around the bridge, which reportedly “ate a big loader tractor like candy.” By July 21, flood waters had washed out parts of the bridge, according to video footage published by The Guardian.
在国家冰雪数据中心的首席科学家Ted Scambos说道,“这是融化惊人的一年”。 “尽管融水大多在格陵兰冰原的上部再冻结,降低了冰盖融化进程,停止了排入河流和小溪及入海。”大约在同一时间, ALI 获得的7月12日图像,在地面上的观察员惊叹于桥附近的高水位,据报道“吞没大装载机拖拉机就像吃糖果一样。”根据卫报公布的录像,7月21日,洪水冲出了桥梁一部分。
帖子中涉及地图来源广泛,图中所涉及的行政区域以中国官方认定的为准。
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发表于 2012-7-27 10:20 | 显示全部楼层
北极海冰马上追上2007年。
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