Arctic Sea Ice Minimum in 2013 Is Sixth Lowest On Record
Sep. 21, 2013 — After an unusually cold summer in the northernmost latitudes, Arctic sea ice appears to have reached its annual minimum summer extent for 2013 on Sept. 13, the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado in Boulder has reported. Analysis of satellite data by NSIDC and NASA showed that the sea ice extent shrunk to 1.97 million square miles (5.10 million square kilometers).
This year's sea ice extent is substantially higher than last year's record low minimum. On Sept.16, 2012, Arctic sea ice reached its smallest extent ever recorded by satellites at 1.32 million square miles (3.41 million square kilometers). That is about half the size of the average minimum extent from 1981 to 2010.
올해 얼음면적은 작년의 최저기록보다 대체로 높습니다. 2012년 9월 16일 북극 얼음은 341,000 제곱 킬로미터로, 위성기록자료 중 가장 작은면적을 차지했습니다.
This summer's minimum is still the sixth lowest extent of the satellite record and is 432,000 square miles (1.12 million square kilometers) lower than the 1981-2010 average, roughly the size of Texas and California combined.
이번 여름 최소값은 아직 위성기록자료 중 6번째로 가장 작은 값이고 이 것은 112000 제곱 킬로미터 적습니다 1981~12010 평균값보다, 대략 택사스와 캘리포니아를 합한 정도의 사이즈인,
The 2013 summertime minimum extent is in line with the long-term downward trend of about 12 percent per decade since the late 1970s, a decline that has accelerated after 2007. This year's rebound from 2012 does not disagree with this downward trend and is not a surprise to scientists.
2012년 여름 최소면적은 1970년대 이후로 부터 연간 약 12%정도 오랜기간 감소하는 추세과 관련이 있다, 2007년 이후부터 더 가속화하는 감소. 올해의 2012년에서 비롯된 반향은(rebound from) 이 감소추세를 disagree 하지 않는다, 그리고 과학자들에게 놀랄일은 아니다.
"I was expecting that this year would be higher than last year," said Walt Meier, a glaciologist at NASA's Goddard Space Flight Center in Greenbelt, Md. "There is always a tendency to have an uptick after an extreme low; in our satellite data, the Arctic sea ice has never set record low minimums in consecutive years."
나는 예상 했습니다, 올 해는 작년보다 높아질 것이라고" Walt Meier 가 말했다, 그린벨트에 있는 나사의Goddard Space Flight Center의 Md (Managing directer?), 빙하연구가, "항상 굉장한 하강 이후에는 상승하는 경향이 있습니다,; 우리의 위성자료에서는, 북극해 얼음은 절대 수년간 연속적인(consecutive) 최저값을 기록하지 않습니다."
The ice cap covering the Arctic Ocean shrinks and expands with the passing of the seasons, melting in the summer and refreezing during the long, frigid Arctic winter. This year, cooler weather in the spring and summer led to a late start of the melt season and overall less melt.
북극을 덮고있는 얼음 cap은 줄어들고 팽창한다, 계절이 지나가는 것 과 같이, 여름에 녹고 다시 얼게된다 길고 매우추운 북극의 겨울동안. 올해는 봄에 더 서늘한 날씨였다, 그래서 여름이 (얼음이)녹는 계절의 늦은 시작으로 연결되고 전반적으로 적게 녹았다.
This year, Arctic temperatures were 1.8 to 4.5 degrees Fahrenheit (1 to 2.5 degrees Celsius) lower than average, according to NASA's Modern Era Retrospective analysis for Research and Applications, a merging of observations and a modeled forecast. The colder temperatures were in part due to a series of summer cyclones. In August 2012, a big storm caused havoc on the Arctic Ocean's icy cover, but this summer's cyclones have had the opposite effect: under cloudier conditions, surface winds spread the ice over a larger area.
올해는 북극의 온도가 1~2.5도 평균보다 낮았다, 리서치와 적용을 위한 나사의 현세시대 retrospective 해석에 따르면, 관찰과 모델예측의 합작인. 더 추운 온도는 일부입니다, 여름 사이클론의 연속 때문입니다.
"The trend with decreasing sea ice is having a high-pressure area in the center of the Arctic, which compresses the ice pack into a smaller area and also results in clear skies, which enhances melting due to the sun," said Richard Cullather, an atmospheric scientist at Goddard and at the Earth System Science Interdisciplinary Center of the University of Maryland, College Park, Md. "This year, there was low pressure, so the cloudiness and the winds associated with the cyclones expanded the ice."
The remaining Arctic sea ice cover is much thinner on average than it was years ago. Satellite imagery, submarine sonar measurements, and data collected from NASA's Operation IceBridge, an airborne survey of polar ice, indicate that the Arctic sea ice thickness is as much as 50 percent thinner than it was in previous decades, going from an average thickness of 12.5 feet (3.8 meters) in 1980 to 6.2 feet (1.9 meters) in recent years. The thinning is due to the loss of older, thicker ice, which is being replaced by thinner seasonal ice.
Most of the Arctic Ocean used to be covered by multiyear ice, or ice that has survived at least two summers and is typically 10 to 13 feet (3 to 4 meters) thick. This older ice has declined at an even faster rate than younger ice and is now largely relegated to a strip along the northern coast of Greenland. The rest of the Arctic Ocean is dominated by first year ice, or ice that formed over the previous winter and is only 3 to 7 feet (1 to 2 meters) thick.
"Thinner ice melts completely at a faster rate than thicker ice does, so if the average thickness of Arctic sea ice goes down, it's more likely that the extent of the summer ice will go down as well," said Joey Comiso, senior scientist at Goddard and coordinating lead author of the Cryosphere Observations chapter of the upcoming report of the Intergovernmental Panel on Climate Change. "At the rate we're observing this decline, it's very likely that the Arctic's summer sea ice will completely disappear within this century."
Comiso added that the slight rebound in the 2013 sea ice minimum extent is consistent with a rebound in the multiyear ice cover observed last winter.
"The character of the ice is fundamentally different: It's thinner, more broken up, and thus more susceptible to melt completely," Meier said. "This year, the cool temperatures saved more of the ice. However, the fact that as much of the ice melted as it did is an indication of how much the ice cover had changed. If we had this weather with the sea ice of 20 years ago, we would have had an above-normal extent this year."
