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【○隻字片羽○雪泥鴻爪○】



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既然有緣到此一訪,
何妨放鬆一下妳(你)的心緒,
歇一歇妳(你)的腳步,
讓我陪妳(你)喝一杯香醇的咖啡吧!

這裡是一個完全開放的交心空間,
躺在綠意漾然的草原上,望著晴空的藍天,
白雲和微風嬉鬧著,無拘無束的赤著腳,
可以輕輕鬆鬆的道出心中情。

天馬行空的釋放著胸懷,緊緊擁抱著彼此的情緒。
共同分享著彼此悲歡離合的酸甜苦辣。
互相激勵,互相撫慰,互相提攜,
一齊向前邁進。

也因為有妳(你)的來訪,我們認識了。
請讓我能擁有機會回拜於妳(你)空間的機會。
謝謝妳(你)!

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2018年5月30日 星期三

Migration forecasts could help prevent wind turbines and buildings from killing millions of birds


http://www.sciencemag.org/news/2018/04/migration-forecasts-could-help-prevent-wind-turbines-and-buildings-killing-millions



Red-winged blackbirds on the move in Klamath Basin National Wildlife Refuge Complex in California
MINT IMAGES LIMITED/ALAMY STOCK PHOTO

Migration forecasts could help prevent wind turbines and buildings from killing millions of birds


Each spring, billions of birds fly vast distances to spend the summer in North America, most of them traveling at night. It's a trip fraught with peril: Many slam into wind turbines or brightly lit buildings. Now, a new forecasting system for bird migration could help put an end to millions of those deaths by warning wind farm operators and building managers of incoming migrations 3 days in advance.
Although hawks and other large species migrate during the day, most small birds migrate at night to avoid predators and enjoy better flying conditions. The daily legs of these migrations depend heavily on the weather. If conditions are too cold or rainy, migrants hang out in trees until the skies clear. And birds are more likely to continue their journeys when warm air signals an incoming, southerly tailwind. Since 2012, the Cornell Lab of Ornithology has made predictions about these migrations by using observer sightings and regional weather reports on its BirdCast website.
To scale up and automate these forecasts Benjamin Van Doren, a Ph.D. student at the University of Oxford in the United Kingdom, and Kyle Horton, a postdoc at the Cornell lab, built a computer model of weather and bird migration. They began with weather radar, the only effective way to monitor night-time migrations. Individual birds can't be detected, but radar can reveal the density of birds in the airspace: 60 to 70 birds per cubic kilometer in a light migration, and as many as 1700 in a heavy one.

Van Doren and Horton calculated the number of migratory birds on a massive scale. They analyzed radar images from 143 sites across the continental United States, examining the same half-hour period each night between March and May, the migration season. By looking at records from 1995 to 2017, they also were able to estimate for the first time the average number of birds migrating on any given night across the entire United States: about 200 million, they report on the preprint server bioRxiv. The mass movement peaks at 520 million birds, typically in early May.

This automated forecast predicts bird migration intensity based on weather patterns. 
BIRD CAST, CORNELL LAB OF ORNITHOLOGY, VAN DOREN AND HORTON 2018, ADAPTED BY J. ADAMS/SCIENCE
Next, Van Doren and Horton compared all these movements to the local weather at the time when birds began a particular leg of their journey. They found that air temperature was the most powerful predictor of how many birds would be flying that night. By combining forecasts of air temperature and other factors such as air pressure and wind, they constructed a model that could reliably predict bird movements up to 3 days in the future, and they suspect that longer forecasts are possible. "It's impressive how precise the prediction is, and how accurate," says Wouter Vansteelant, a freelance bird migration researcher in Bennekom, the Netherlands, who was not involved in the research.
BirdCast is now posting automated forecasts for the entire United States. "This is the most significant update since we first began using radar to study bird movements," Horton said in a statement. The Cornell team hopes that in addition to telling birdwatchers where and when to spot migratory species, the forecast will help owners of tall buildings know when to turn off unnecessary lights. Moreover, wind farms—some of which employ monitors to watch for hawks and other daytime migrants—might shut down turbines when waves of nighttime migratory birds are about to pass through.  

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