加州冬季吐尔雾的频率大幅下降
文章来源:未知 文章作者:enread 发布时间:2014-05-22 06:28 字体: [ ]  进入论坛
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California's winter tule fog -- hated by drivers, but needed by fruit and nut trees -- has declined dramatically over the past three decades, raising a red flag for the state's multibillion dollar agricultural industry, according to researchers at UC Berkeley. Crops such as almonds(杏仁), pistachios(开心果), cherries, apricots and peaches go through a necessary winter dormant1 period brought on and maintained by colder temperatures. Tule fog, a thick ground fog that descends2 upon the state's Central Valley between late fall and early spring, helps contribute to this winter chill.
 
"The trees need this dormant time to rest so that they can later develop buds, flowers and fruit during the growing season," said biometeorologist and study lead author Dennis Baldocchi, whose father grew almonds and walnuts3 in Antioch and Oakley. "An insufficient4 rest period impairs5 the ability of farmers to achieve high quality fruit yields."
 
The study was published May 15 in the journal Geophysical Research Letters, a publication of the American Geophysical Union. The findings have implications for the entire country since many of these California crops account for 95 percent of U.S. production, the authors noted6.
 
The researchers paired NASA and National Oceanic and Atmospheric7 Administration satellite records with data from a network of University of California weather stations, covering 32 consecutive8 winters. There was a great deal of variability from year to year, but on average, the researchers found a 46 percent drop in the number of fog days between the first of November and the end of February.
 
"The year-to-year variability we saw was likely influenced by whether the season was relatively9 wet or dry," said Baldocchi, professor of Environmental Science, Policy and Management. "Generally, when conditions are too dry or too wet, we get less fog. If we're in a drought, there isn't enough moisture to condense(浓缩,凝结) in the air. During wet years, we need the rain to stop so that the fog can form."
 
Other studies have marked the decline in the Central Valley of winter chill -- the number of hours between 0 and 7 degrees Celsius10. The number of hours of winter chill has dropped by several hundred since the 1950s, the study authors noted.
 
But ambient air temperature alone may not adequately reflect the heat experienced by the crops, said Baldocchi. Direct sunlight can heat the buds so that they are warmer than the surrounding air temperature. As a result, fog is important in shielding the buds from the sun and helping11 them accumulate winter chill.
 
Climate forecasts suggest that the accumulation of winter chill will continue to decrease in the Central Valley. Baldocchi said that fruit developers are already trying to develop cultivars that can tolerate less winter chill.
 
"Farmers may also need to consider adjusting the location of orchards12 to follow the fog, so to speak," said Baldocchi. "Some regions along the foothills of the Sierra are candidates, for instance. That type of change is a slow and difficult process, so we need to start thinking about this now."


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1 dormant d8uyk     
adj.暂停活动的;休眠的;潜伏的
参考例句:
  • Many animals are in a dormant state during winter.在冬天许多动物都处于睡眠状态。
  • This dormant volcano suddenly fired up.这座休眠火山突然爆发了。
2 descends e9fd61c3161a390a0db3b45b3a992bee     
v.下来( descend的第三人称单数 );下去;下降;下斜
参考例句:
  • This festival descends from a religious rite. 这个节日起源于宗教仪式。 来自《简明英汉词典》
  • The path descends steeply to the village. 小路陡直而下直到村子。 来自《简明英汉词典》
3 walnuts 465c6356861ea8aca24192b9eacd42e8     
胡桃(树)( walnut的名词复数 ); 胡桃木
参考例句:
  • Are there walnuts in this sauce? 这沙司里面有核桃吗?
  • We ate eggs and bacon, pickled walnuts and cheese. 我们吃鸡蛋,火腿,腌胡桃仁和干酪。
4 insufficient L5vxu     
adj.(for,of)不足的,不够的
参考例句:
  • There was insufficient evidence to convict him.没有足够证据给他定罪。
  • In their day scientific knowledge was insufficient to settle the matter.在他们的时代,科学知识还不能足以解决这些问题。
5 impairs 866bc0da43dd90e04b6073750ff1e87c     
v.损害,削弱( impair的第三人称单数 )
参考例句:
  • Smoking impairs our health. 吸烟会损害我们的健康。 来自《简明英汉词典》
  • Almost anything that impairs liver function can cause hepatitis. 任何有损于肝功能的因素,几乎都会引起肝炎。 来自辞典例句
6 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
7 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
8 consecutive DpPz0     
adj.连续的,联贯的,始终一贯的
参考例句:
  • It has rained for four consecutive days.已连续下了四天雨。
  • The policy of our Party is consecutive.我党的政策始终如一。
9 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
10 Celsius AXRzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
11 helping 2rGzDc     
n.食物的一份&adj.帮助人的,辅助的
参考例句:
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
12 orchards d6be15c5dabd9dea7702c7b892c9330e     
(通常指围起来的)果园( orchard的名词复数 )
参考例句:
  • They turned the hills into orchards and plains into granaries. 他们把山坡变成了果园,把平地变成了粮仓。
  • Some of the new planted apple orchards have also begun to bear. 有些新开的苹果园也开始结苹果了。
TAG标签: winter trees fog
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