本帖最后由 林夏 于 2009-6-19 17:49 编辑
这是“日食资料翻译组织人手”里申请的2.3节
原帖见：http://www.astronomy.com.cn/bbs/thread-111450-1-1.html
原文见：http://eclipse.gsfc.nasa.gov/SEpubs/20090722/TP214169a.pdf
2.3 China
2.3 中国
Past Dibrugarh, the central line moves into the mountainous terrain that separates India and China. Peaks in the region reach above 7,000 m and transportation is difficult and limited.
在经过Dibrugarh（迪格博伊，Assam邦，印度——译注），日食中心线进入印度和中国交界的山区。这个地区的山峰都高达7，000米以上，交通在这里困难而且受限制。
Weather observations are few in number, but the satellite-based cloud observations show a zigzag series of ups and downs in the average cloud amount where the path crosses between the two countries. Each rise correlates with the windward-facing slope of the terrain, while declines in cloudiness are found in valleys on the leeward side. There is a general downturn to the average cloud amount from its peak in India, but cloudiness does not drop below 60% until the track has departed the higher mountains and begun its journey across the plains of China at Chengdu and Leshan.
天气观测总数上是很少的，但是基于卫星的云量观测显示，在这两个国家之间的食径穿过的地方，平均云遮比呈现出一个高低起伏的之字形。图中每一处云量的上升都与迎风面斜坡相关，同时，云量的下降出现在背风面的山谷。从图中印度的最高点（Guwahati——译注）开始，会有普遍的趋势下降到平均云遮比，然而，直到日食轨迹离开高山区并从成都和乐山起穿越中国的平原时，云遮比才低至60%以下。
China has its own monsoon flow, separate from that of India because of the barrier imposed by the Plateau of Tibet that arcs along its western border. Instead, winds bring moisture into China from the south and east, and so the west side of the higher terrain, where winds flow down hill, is favored with sunnier skies.
中国有自己的季风流，与印度的不同，中国的季风流是由西藏高原西边缘的弧形地带的屏障导致的。取而代之的是，风把水汽由南向东带入中国，因此，地势更高的西边（风从那里吹向丘陵）会有更晴朗的天空。
Figure 21 shows a decline in cloudiness to between 50% and 60% at Chengdu and Chongqing—a value that remains more or less constant across the rest of the eclipse path through China. Both these cities lie in the Yangtze River basin and so the descending monsoon air warms and dries as it moves into the valley. Between Chongqing and Yichan, the cloudiness climbs about 10% as the track moves across the 2000-m to 3000-m peaks of the Fangdou Shan.
图21显示了成都和重庆的云量下降到50%和60%之间——这个云遮比将几乎保持这个常数状态，直到食径穿过中国境内余下的部分。这两个城市都在长江流经的盆地，当下沉的季风进入谷中，空气会很温暖和干燥。图中重庆和宜川之间，云遮比上升了大约10%，因为食径经过高达2000-3000米的四川方斗山。
Once across the Fangdou Shan, the eclipse path descends once again into the lush lowlands surrounding Wuhan. Spacebased cloud observations show that Wuhan has sunshine prospects slightly lower than Chongqing, but surface-based observations give it the nod as the most promising inland site in China. Average cloud cover derived from local weather records (Table 17) is a discouraging 61%, one of the best in China, but is high compared to cloud amounts at recent eclipses in other parts of the globe.
一旦越过了方斗山，食径再一次落到武汉周边草木茂盛的低地。基于空间的云量观测显示武汉天晴的可能性稍微比重庆低些，但是基于地表的观测给出了肯定的结论，武汉是中国最有希望的内陆地区。从当地气象记录（表17）得到的平均云遮比是令人沮丧的61%，虽然是中国最好的一个，但却是过去几次世界其他地方的日食中比较高的云量。
Wuhan’s biggest advantage over sunnier sites near the coast is the lower amount of haze and pollution. The city is relatively compact, but open sites in the countryside have to be sought out, as the area is extensively agricultural and sites for large groups are at a premium. The central line of the eclipse passes through the airport, so that sites within the city proper may be quite suitable, and Wuhan has a good assortment of public parks and waterside enclaves. It is an area well worth exploring for an eclipse site, as the cleaner skies compared to sites near Shanghai will allow the distant corona to stand out more clearly against the sky.
与长江沿岸更为晴朗的地方相比，武汉的最大优势在于较少的雾气和污染。武汉这城市的布局相对简洁，但是也不得不去寻找乡下开阔的地方，即便乡下都是广阔的农田，但是提供给大型组织的地点是很短缺的。日食中线心经过机场，所以城市内的地点也许会相当合适，武汉有各种各样的公园和江中小洲（或直接叫“渚”、“洲”、“沚”——译注）。这是一个很值得考察的日食观测点，因为比上海周遭更加清洁的天空，将会使得离太阳很远的日冕相对天空背景更加显眼。
East of Wuhan, the eclipse track crosses 1000-m peaks of the Dabie Shan and descends onto the coastal plain to Shanghai and Hangzhou. Cloud amounts bump upward over the Shan, but then cloud percentages settle into the mid-50s on the plain, marking the best that China has to offer. It is a grimy region, with plenty of pollution from the huge human presence, but the eclipse is high in the sky where the effects of the brownish haze are less evident on a sunny day.
武汉的东部，日食轨迹越过1000米高的大别山，然后向沿海平原下降，直到上海和杭州。云量在大别山时猛然增大，但是之后，平原上的云遮比稳定在50%左右，意味着中国最好的地方。这个地区比较脏，有很多来自人类的污染，但是日食时太阳在天空中比较高，晴天时褐色的雾气对日食的影响较为不明显。
Daily satellite images show a dynamic cloudiness across the whole of south and central China. A broad band of deep, cold-topped layers of overcast cloud will mark the location of the mei-yu while broken patches of lower cloud dot the remaining landscape. Occasionally, large areas of nearly clear skies will open up, lingering for a day or two before re-filling with cloud. Moreover, on rare occasions, the mei-yu seems to wither away to scattered cloudiness, bringing large areas of sunshine across the whole country. Examination of satellite images from 2006 and 2007 reveals that the southern boundary of the front typically lies near Shanghai, leaving the city and the eclipse track in an area tantalizingly close to sunnier weather. Slight motions of the front northward or southward bring alternating periods of overcast skies and sunshine through the month.
每天的卫星云图显示了横跨中国中部和南部的动态云量。一个很厚的宽阔的云带和顶端较冷的致密云将会影响梅雨锋的位置，同时破坏较低的云块，零星分布在剩余的天空中。有时候，大部分相当洁净的天空将会展露出来，而且在重新布满云朵之前持续一至两天。此外，难得的情况是梅雨似乎消退了，变成了疏云，并带来大范围的遍及整个国家的晴天。检查2006和2007的卫星云图，显示锋面的南边界通常靠近上海，使得上海和日食轨迹处于一个迫切需要更加晴朗天气的地区。锋面缓慢地向北或向南移动，在这个月内带来阴雨天和晴天的相互交错。
The climatological behavior of the front cannot be reliably ascertained from just two years of monitoring. Longer-term statistics award Shanghai with slightly more sunshine than other parts of China.
仅仅从这两年的的监测来看，锋面的气候变化不能完全可靠地被确定下来。长期的数据统计指向上海拥有比中国其他地方更多晴朗的天气。
Southeast of Shanghai, the eclipse track meets the coast and moves across the South China Sea. A part of the cloudiness associated with the monsoon climate is generated by instability and convection driven by daytime heating, so sites along the coast should be somewhat sunnier than those inland because of cooling that comes with proximity to the water. Shanghai has two airports, one inland (Hongqiao) and the other on the coast (Pudong). Cloud statistics in Table 17 show that the average cloudiness at Pudong is much lower than at Hongqiao (50% versus 67%). Pudong, however, is a new airport, and statistics from the area are only available since 2004, a period too short to accurately reflect the climatological cloudiness.
上海的东南方，日食轨迹将会和海岸接触，然后移向南中国海（和南海有什么关系？是东海吧——译注）。其中一部分和季风性气候有关的阴雨天，是由不稳定的以及受到白天的热量驱使而产生的对流天气造成的，由于同时靠近水域而使气流冷却，因此沿海地方应该稍微比那些内陆地区晴朗点。上海有两个机场，一个不靠海（虹桥机场），另一个就在海边（浦东机场）。表17的云量统计显示，浦东机场的平均云遮比比虹桥机场低得多（50% vs 67%）。而然，浦东机场是个新机场，这个地区的可以信赖的统计数据仅仅从2004年开始，时段太短以致于不能准确反映气候上的云量。
A comparison of the four years in common between the two airports reveals that Pudong’s cloud cover is only about 4% lower than that at Hongqiao, a value that is much more in line with satellite data. In a climate where cloudiness rules, this 4% difference is significant, and argues strongly for a viewing site right on the waterfront, southeast of Shanghai where the central line crosses the coast. One of the better choices is at Jinshan (or Jinshanwei), a coastal city just north of the shadow axis. Jinshan has the distinction of being the site of a large artificial beach that is being constructed for the benefit of Shanghai and local residents.
经过四年的时间、两个机场之间共同的比较，显示了浦东机场的云遮比仅仅比虹桥机场低4%，这个数值更符合卫星数据。在一种多云规律的气候中，4%的差异是不可忽略的，并且为在岸边（上海东南方，中心线穿过的海岸。）的观测点是否正确而激烈的争论。较好的选择之一是金山区（或者金山卫镇）——刚好位于影子轴（就是中心线——译注）北部的一个沿海城市。金山区的不同点在于有一个巨大的人工海岸，这个人工海岸对于上海和当地的居是极其有益的。
Beachfront sites can be windy, so prudence dictates a retreat of a few hundred meters inland to obtain shelter from the onshore winds. Prevailing winds in the Shanghai area are from the south and southeast, a direction that brings the cooler and cleaner air from the South China Sea onto the land.
沿海岸地方多风，因此要慎重指定一个离岸边几百米的避难所，以躲避上岸的风。上海地区的盛行风[1]来自南方和东南方，一种倾向是会把来自南中国海的更凉快和更干净的空气带到陆地上。
[1]盛行风：又称最多风向，是指一个地区在某一时段内出现频数最多的风或风向。通常按日、月、季和年的时段用统计方法求出相应时段的盛行风向。盛行风带往往与一地的环流条件有密切关系。例如，在中东纬度西风带一般盛行西风，在信风带上往往盛行偏东风。但有时它也与局地地形有关。例如，在中国渭河流域，由于地形限制，往往盛行东西向的风。盛行风的下风地区首污染的影响最大。在晴天的夜间，风速较小，近地面积几百米高度易出现辐射逆温层，大气稳定，污染物的扩散能力差。在中午前后，温度垂直递减率增大，热力和动力湍流发展，污染物的扩散能力增强。了解一个地区的盛行风向，对于天气预报及城市规划、环境污染等研究都是十分有意义的。
FIG 21
TAB 17
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