NASA啟動了最新一期的北極海冰空中調查

(本文翻譯自NASA:NASA Begins Latest Airborne ArcticIce Survey)

An unusual hole in the sea ice cover over the

Arctic Ocean and unexplored areas of the bedrock beneath the Greenland Ice

Sheet are among the targets for this year』s mapping of Arctic ice conditions by

NASA』s Operation IceBridge airborne mission.

在格陵蘭冰蓋未開發的基岩地區出現的不同尋常的洞是今年NASA進行的眾多北極海冰空中調查項目的目標之一。

This year marks the tenth Arctic spring campaign for Operation IceBridge, a

cryosphere-focused mission tasked with mapping the fastest-changing areas of

the Greenland Ice Sheet and measuring sea ice thickness across the western

Arctic basin.

今年計划了十次北極春季IceBridge調查項目，今年的任務有標記格陵蘭冰蓋變化最快的地區以及測量北極西部的冰層厚度。

On March 22, NASA completed the first IceBridge

flight of its spring Arctic campaign with a survey of sea ice north of

Greenland. This year marks the tenth Arctic spring campaign for IceBridge. The

flights continue until April 27 extending the mission』s decade-long mapping of

the fastest-changing areas of the Greenland Ice Sheet and measuring sea ice

thickness across the western Arctic basin.

3月22號，NASA在格陵蘭島北部完成了第一次剩餘海冰空中調查的飛行。今年計划了十次北極春季冰架調查。飛行將延遲到4月27號結束，來完成標記格陵蘭冰蓋變化最快的地區以及測量北極西部的冰層厚度的任務。

The IceBridge team and instruments are flying on NASA』s

P-3 Orion. The plane carries a dual-color laser altimeter that measures surface

elevation by transmitting both infrared and green laser pulses, three types of

radar systems to study ice layers and Greenland』s bedrock, a high-resolution

camera to create color maps of polar ice, a hyperspectral imager that takes

measurements over hundreds of wavelengths, and infrared cameras to measure

surface temperatures of sea and land ice.

科考隊員和科研設備搭載在NASA的P-3獵戶座反潛機上，飛機裝備有雙色激光測高儀，通過發射紅外和綠色激光脈衝測量表面高度；三種雷達系統用來研究冰層和格陵蘭島的基岩；一台高解析度相機來拍攝極地冰層的彩色地圖；一台測量範圍有數百個波長的高光譜成像儀；一台紅外相機用來測量陸地和海上冰層的溫度。

IceBridge continued observations of changes in polar ice elevation

after the end of NASA』s Ice, Cloud, and land Elevation Satellite (ICESat)

mission in 2009. That satellite』s successor, ICESat-2, is scheduled to launch

this September.

對於冰架和冰層高度的變化的監視自從2009年NASA結束了ICESat衛星的任務之後就一直進行，ICESat衛星的後繼者：ICESat-2準備將於今年九月發射。

「After this season』s campaign, IceBridge will have bridged the gap

between the ICESat and ICESat-2 record of measurements,」 said Nathan Kurtz,

IceBridge』s project scientist and a sea ice researcher at NASA』s Goddard Space

Flight Center in Greenbelt, Maryland. 「With ICESat-2, we』ll be going back to

observing changes at a global scale and throughout the year, and work will be

underway to connect the ICESat, IceBridge, and ICESat-2 records to better

understand changes in Earth』s polar ice cover in an exciting new way.」

NASA位於格林貝爾特的戈達德太空飛行中心的海冰研究員、冰架計劃的科學家內森·庫爾茲說：「本季度的任務結束後，將彌合ICESat和ICESat-2的冰架間隙測量記錄。」通過ICESat-2，我們將全年進行全球規模的觀察。並且調查將會比較ICESat、IceBridge計劃和ICESst-2所採集的數據用一種令人興奮的新方式來更好的了解北極冰層的變化情況。

During its ten years of operations in the Arctic, IceBridge has

collected a trove of data that goes beyond ice elevation change. It also

includes records of snow accumulation across the ice sheet and snow thickness

over sea ice, measurements of the bedrock topography under the ice sheet and

the shape of the ocean cavity underneath ice shelves.

在今年舉行的10次科考活動中，冰架已經收集了大量關於冰層高度變化的數據，它還包括冰原上積雪堆積和海冰厚度的記錄、冰蓋以下基岩的地形測繪以及冰層下方海洋空腔的形狀。

「The elevation of the ice surface and changes therein are among

the most fundamental things scientists want to know about ice sheets and

glaciers, so that they can assess their state of health,」 said Joe MacGregor, t and a glaciologist at Goddard. 「But we

need to know more than where the ice is thinning and when it started to thin.

We also need to know the why, which is key to projecting what』s going to happen

in the future. So we also measure all these other physical properties to help

us better understand the full ice column and what drives elevation change.」

IceBridge項目的副主管、戈達德的冰河學家喬·麥克雷戈說：「冰川表面海拔的變化是科學家們用來了解冰蓋和冰川的基本，這樣就可以評估出來冰川和冰蓋的整體狀況。」「但是我們也需要知道哪裡的冰正在變薄以及何時開始的變薄。同樣我們也需要知道為什麼，這是預測未來會發生什麼的關鍵，我們還測量了其他的物理參數，以幫助我們來更好的全面了解冰柱和海拔變化的原因。」

The first part of this year』s Arctic campaign is focused on seaice.

The survey flights will run from two bases: Thule Air Base in

northwestGreenland and Fairbanks, Alaska. As with every year, the main priority

will bemapping the thickness of the sea ice cover in the western Arctic through

10planned sea ice surveys.今年北極戰役中的第一部分集中在了海冰上。調查航班將從兩個基地出發：格陵蘭島西北部的圖爾空軍基地和阿拉斯加的費爾班克斯。與往年一樣，主要任務為通過十次海冰調查來測量西部北冰洋的海冰覆蓋程度。

The IceBridge team andinstruments will also probe a big polynya —a

hole in the sea ice cover— thatopened up north of Greenland in February.

Normally, this area is covered bysome of the thickest, oldest ice in the

Arctic. The polynya has already sealedup, but scientists worry that the stability

of the sea ice in the region mighthave been jeopardized if the original ice

cover has been replaced with thinnerice.IceBridge

團隊的儀器將檢測一個二月份在格陵蘭島北部發現的大冰間湖——海冰覆蓋下的一個洞。正常情況下，這個區域在北極被最厚最古老的的冰層覆蓋。雖然這個冰間湖已經被封存，但科學家擔心若是原有的厚冰層被新生的較薄的冰層取代，該地區海冰的穩定性可能會受到破壞。

Snow-covered pack sea ice north of Greenland.Credits: NASA/Jeremy

Harbeck「Two processes might havecaused the polynya to

close: either winds and currents pushed the pack icesouth up against the coast,

or the surface refroze,」 said John Sonntag,Operation IceBridge』s mission

scientist. 「The two processes would look similarin some satellite imagery, but

very different in our measurements. If theformer occurred, the ice that filled

the polynya should be quite thick and havea fair amount of snow on top. If

refreezing was the cause, this new icewould be very thin, with little snow on

it. Either way, we should see it.」

「風和洋流把浮冰向南推進擠壓海岸線，或者海面上的冰層重新凍結可能導致了冰間湖的閉合。」IceBrige行動的科學家約翰桑納格說，「儘管這兩個過程在衛星圖像上看起來很相似，但在實際測量中十分不同。前者如果發生，那麼冰間湖上的冰將會是非常厚的並應積有一定量的雪。如果原因是冰層重新凍結，新冰會非常薄，雪量也會小。但不管哪種，我們都能看到它。」

After completing the sea iceflights and a few land ice flights in

northern Greenland and Alaska, IceBridgewill move its base of operations on

April 12 to Kangerlussuaq, in centralwestern Greenland, and measure land ice.

The goal is to perform about 12 landice flights in total, ten of which are high

priority surveys that are repeatedevery year to gauge annual changes in

elevation in fast-evolving areas or alongfuture ICESat-2 tracks. Among the

possibilities for the remaining two flightsare plans to explore never-before

measured areas in Greenland to improve mapsof the island』s bedrock topography.

在完成了格陵蘭島和阿拉斯加北部的海冰飛行和幾次陸地冰的飛行後，IceBridge將會於4月12日把基地移到格陵蘭島中部的Kangerlussuaq然後測量陸地冰層。目標是完成12次陸地冰層測量的飛行，十次高級優先的測量是每年都要重複的關於發展中地區或未來的ICESat-2軌道的。其餘兩次測量應該會測量格陵蘭島上從未被測量過的地區，以改善島上基岩地形的地圖。

「These are areas of the icesheet that – while flowing relatively

slowly – have no measurementspresently,」 MacGregor said. 「Even after all these

years of NASA andinternational effort, there are still contiguous areas of the

Greenland icesheet hundreds of square miles in size where no bedrock topography

measurementshave been collected.」

麥克格雷戈說：「這些是冰層覆蓋的區域，雖然流動相對緩慢，但目前還沒有測量數據。即使經過了這麼多年NASA和國際組織的努力，格陵蘭島仍有數百平方英里的區域沒有基岩的地形測量數據。」

While flying over theArctic, IceBridge will collaborate scientifically with satellite

missions andinternational research groups. During the sea ice surveys, the

IceBridge planewill fly under the tracks of the European Space Agency』s

CryoSat-2 andSentinel-3 satellites, and over the field camp of an international

group ofresearchers studying fast ice –sea ice attached to the coast—north of

StationAlert, in the Canadian Arctic. While collecting land ice data, IceBridge

willfly over sections of the ice also being studied by teams from Ohio State

Universityand Germany』s Alfred Wegener Institute. Scientists will afterward

compare thedifferent radar and laser datasets.

在飛越北極上空時，IceBrige將與衛星任務和國際研究小組進行科學合作。在海冰調查中，IceBrige的飛機將會在歐洲航天局冰雪衛星-2和3-3衛星的軌道下以及一個國際小組的營地上進行飛行，研究人員在海冰與海岸線相連的加拿大的北極地區研究海冰。在收集陸地冰層的數據時，IceBrige的飛機將會飛過部分冰區，俄亥俄州立大學和德國的阿爾弗雷德魏格納研究所也正在研究這一問題。科學家將會對比不同的雷達和激光數據。

翻譯： @增智同學 @Yshh 小花

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