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[定期翻译]《经济学人》Weather Forecasting:Continental divide

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更多 发布于:2015-02-08 23:29
Weather forecasting:Continental divide
天气预报:洲际差距

(译注:《经济学人》典型双关标题。Continental divide字面上意为大洲之间的分隔,组合起来的短语特指美国本土分隔太平洋流域和大西洋流域的分水岭。)

Europeans do not just talk about the weather more than Americans do. They are better at forecasting it as well
欧洲人比美国人在天气上不仅聊得多,而且还预报得好

IT WAS far too small a victory to count as an equaliser. But cheers were still heard in American meteorological circles after the storm that hit the country’s east coast last month left the city of New York mostly unscathed. For more than two decades the Global Forecast System (GFS), the leading weather-prediction model produced in the United States, has been notably less accurate than its chief competitor, published by the European Centre for Medium-Range Weather Forecasts (ECMWF). Although this deficit went largely unnoticed for years, it was laid bare by Hurricane Sandy. A week before that storm’s landfall in 2012, the ECMWF predicted it would veer towards the coast while the GFS showed it remaining at sea.
这场胜利来得实在太小,根本不够扳平比分。尽管如此,美国气象界内仍然响起了欢呼声——在上个月一场袭击美国东海岸的风暴中,纽约并未受严重影响。全球预报系统(GFS)作为美国领导性的天气预报数值模式,在长达二十余年的时间里一直在精确性上显著落后于其首要竞争对手——由欧洲中期天气预报中心(ECMWF)出品的数值模式。这一差距长期未受注意,直到飓风桑迪将其暴露在世人眼前。2012年,早在桑迪登陆一周前,ECMWF就预报飓风将移向海岸,而GFS预报飓风将留在海上。



图片:20150207_STP001_0.jpg


In response to this failure, America’s Congress authorised $34m of extra money to spend on forecasting. A new version of the GFS went into operation on January 14th, and two weeks later it passed with flying colours. On January 25th the ECMWF predicted that New York would, on the 27th, labour under 64cm (25 inches) of snow brought by the storm pictured above. The GFS suggested 18cm. That turned out to be far closer to the truth.
为了应对这次失利,美国国会额外批准了3400万美元预算用于预报。1月14日,新版GFS投入运营,两周后便获得了一次大胜。1月25日,ECMWF预测上图中的风暴将在27日给纽约带来多达64cm的降雪。GFS则认为只有18cm,远比ECMWF符合实际情况。



It is, however, too early for the Americans to celebrate. The GFS projection for the blizzard’s western edge differed from the ECMWF’s by 200km (120 miles)—a weather-forecasting hairs’-breadth. The only reason anyone noticed this discrepancy was that the gap happened to encompass the country’s most populous city.
不过这仍不是美国人庆祝的时候。GFS预报出的暴雪区域西侧边缘和ECMWF相比相差了200km,这对于天气预报来说不过是毫厘之间。这一差距为人注意的唯一原因是差异区域恰好覆盖了这个国家人口最多的城市。



This episode, moreover, may have been a fluke. During its three weeks of operation, the new GFS remained outclassed. On a standard measure—predicting the altitude at which the atmospheric pressure is half as great as at sea level—it still trails the ECMWF model.
而且这一胜利很可能不过是一时走运而已。新版GFS在它运营的三周时间里仍然完败于对手。在数值预报的标准评测——500百帕形势预报——中,GFS仍然落后于ECMWF。


Nonetheless, the GFS’s strong showing during January’s nor’easter offers solace to critics who feared America would never catch up with Europe in matters meteorological. Weather forecasting is fiendishly complex, and improvements tend to arise not from great leaps forward but rather an accumulation of incremental advances.
尽管如此,GFS在这次冬季风暴中的强劲表现,还是给那些担忧美国在气象学上永远赶不上欧洲的批评家们带来了安慰。天气预报极其复杂,难得有一蹴而就的大进步,更多的则是慢慢积累的改善。


The ECMWF’s most obvious advantage has been in raw computing power. Its Cray XC30 supercomputer can perform up to 2 quadrillion calculations a second, about ten times more than the GFS hardware before the recent upgrade. As a result, it carves up the Earth’s atmosphere into svelte cells 16km square and 137 layers deep, compared with a bulky 27km and a mere 64 layers for the old GFS. The ECMWF’s computing muscle also lets it start its projections with a replay of the past 12 hours of weather, using 40m data points derived from observations collected by ground stations, aeroplanes, balloons and satellites. In contrast, the GFS begins with a snapshot of a single moment.
ECMWF最明显的优势体现在其原始计算能力上。其Cray XC30超级电脑每秒可进行两千万亿次运算,是GFS升级前的近十倍。正由于此,ECMWF可将地球大气分割成16km的精细网格和137个层面,让GFS的27km网格和64个层面相形见绌。除此之外,ECMWF的计算力使其能够使用从地面站、飞机、气球和卫星收集而来的4000万个数据点,并依此重建过去12小时的天气,从而开始演算预测。相反,GFS仅从单一时刻开始演算。


The ECMWF also deserves credit for deploying its computational force wisely. The centre was a pioneer in using satellites to fill gaps in the data over the oceans, and in developing “ensemble forecasts” that generate a range of outcomes by employing slightly different starting conditions to produce multiple predictions. Its current model runs 52 such forecasts in parallel, each with a probability assigned to it.
ECMWF在其计算力的应用上亦值得称赞。它是使用卫星数据填补海洋上观测空白这一做法的先驱,也是发展“集合预报”——通过应用细微不同的初始条件从而得到一系列的结果——的先驱。目前,ECMWF同时运行着52个这样的预报,每一个都有其对应的可能性。


Weather forecasters in America have full access to the ECMWF’s model. However, the United States still has good reason not to free-ride on the Europeans’ work. Private American firms have to pay for it, and the ECMWF is unlikely to develop regional or local models focused specifically on America. Moreover, giving the ECMWF a worthy competitor would probably lead to better forecasts overall.
美国的天气预报员可以完全访问ECMWF模式。不过,美国仍然有足够理由不搭欧洲人的便车。美国的私有公司必须购买其模式结果,而且ECMWF也不太可能专为美国设计一个区域化或本地化的模式。更何况,一个有力的对手可以促进ECMWF持续改善其预报。


The new GFS has certainly narrowed the gap. Its resolution is now 13km, though it still has only 64 layers. By November it is expected to run on a faster computer than the ECMWF’s. It could be in line for further upgrades if the new, Republican Congress reintroduces the Weather Forecasting Improvement Act proposed last year—though the party’s global-warming sceptics are likely to demand that much of the additional $120m a year the bill offered be taken away from research on climate change.
新版GFS已经明显缩小了差距。目前其分辨率为13km,尽管它仍然只有64个层面。GFS还计划在11月前在一个比ECMWF更快的超级电脑上运行。如果共和党主导的国会能重新采纳去年提出的天气预报改进法案的话,还可能会有更多的升级——不过该党的全球变暖怀疑论者更可能会大幅削减这笔每年1.2亿计划用于气候变化研究的资金。


According to Cliff Mass, a professor of meteorology at the University of Washington, more money will not be enough to catch up with the Europeans. America, he says, must integrate its separate research and forecasting divisions, and include more contributions from non-government experts. Compared with pushing through cultural change in large public bureaucracies, predicting the weather is easy.
华盛顿大学气象教授Cliff Mass则认为,再多的资金仍无助于赶上欧洲。他认为,美国必须整合其分离的研究和预报部门,同时吸收更多民间专家的成果。和在大型官僚体制里推动政貌改革相比,预报天气简单多了。
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1楼#
发布于:2015-02-11 12:59
之前听大牛说过,GFS弱在之前一段时间只重业务而清科研,但是科研总是走在前面的,科研没有提高,业务水平也很难有所精进。
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禾愛糖
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2楼#
发布于:2015-02-24 17:21
看來颱風預報版未來的未編號的熱帶雲團討論貼將變為GFS
從前的我打倒今天的我。

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格物致知
论坛版主-副热带高压
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3楼#
发布于:2015-02-24 21:02
禾愛糖锛毧磥盹U風預報版未來的未編號的熱帶雲團討論貼將變為GFS鍥炲埌鍘熷笘
感觉ec在热带气旋对gfs的优势本来就非常小。。其实我觉得往往gfs更准。
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发布于:2015-08-09 00:31
用户被禁言,该主题自动屏蔽!
[小马9于2015-12-07 03:55编辑了帖子]
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5楼#
发布于:2015-08-11 15:18
天气预报受到的关注越来越多,是一份动力,更是一份压力。在此压力的鞭策下,大家的预报结果会越来越准确的
Let it be !
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jeremyrocjack
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发布于:2016-02-29 21:07
敢问大神“though the party’s global-warming sceptics are likely to demand that much of the additional $120m a year the bill offered be taken away from research on climate change”中the bill 和 offered各做什么成分啊?请大神赐教!
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7楼#
发布于:2016-03-04 11:08
jeremyrocjack锛毟椅蚀笊瘛皌hough the party’s global-warming sceptics are likely to demand that much of the additional $120m a year the bill o...鍥炲埌鍘熷笘
though the party’s global-warming sceptics are likely to demand that much of the additional $120m a year (which) the bill offered be taken away from research on climate change

我英语语法学的不是很系统,大致的说一下:the bill offered修饰从句主语much of additional $120m a year,由于从句跟的是demand这个动词所以从句中的系动词用be的形式。从句中的主-动-宾用三种颜色标出来了
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jeremyrocjack
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8楼#
发布于:2016-03-04 16:40
谢谢楼主的悉心指导,那offered前面是不是应该有个系动词was表被动?还有the bill的先行词应该是that吧!这里省略了,按理说定语从句中先行词是不能省略的啊?最后:您“由于从句跟的是demand这个动词所以从句中的系动词用be的形式。”是啥意思?本人不才,还望楼主多指教。
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nasdaq
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9楼#
发布于:2016-03-04 23:33
jeremyrocjack锛毿恍宦ブ鞯南ば闹傅迹莖ffered前面是不是应该有个系动词was表被动?还有the bill的先行词应该是that吧!这里省略了,按理说定语从句中先行词是不能省略的啊?最后:您“由于从句跟的是demand这个动词所以从句中的系动词用be的...鍥炲埌鍘熷笘
1.钱是法案提供的,因此无需被动
2.that/which均可,这种情况下可省略
3.demand接的从句使用虚拟语气
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