地下光纜具有監(jiān)測惡劣天氣的潛力

地下光纜具有監(jiān)測惡劣天氣的潛力

Take a moment to think about the surface ground beneath your feet. Plunge deeper still and think about the world unseen. There are networks of tree roots in the soil, but also networks of another sort: fiber-optic cables that connect us to each other via phone and Internet service.

花點時間想想你腳下的地面。再深一些，想想看不見的世界。土壤中有樹根構成的網(wǎng)絡，但也有另一種網(wǎng)絡:通過電話和互聯(lián)網(wǎng)服務將我們彼此連接起來的光纖電纜。

Researchers from Penn State University have developed an innovative idea for piggy-backing on these existing cables: severe weather monitoring. The team turned to their own campus as a testing ground during a thunderstorm on April 15 of this year. Using distributed acoustic sensing (DAS) array technology, they sent a laser down a hair-thin fiber inside miles of cables 1 meter (3.3 feet) deep under the campus and took measurements every 2 meters (6.5 feet), making for a total of 2,000 sensors.

賓夕法尼亞州立大學的研究人員開發(fā)了一種利用現(xiàn)有電纜的創(chuàng)新想法:惡劣天氣監(jiān)測。在今年4月15日的一場雷雨中，該團隊將自己的校園作為試驗場。利用分布式聲波傳感(DAS)陣列技術，他們將一束激光發(fā)射到校園地下1米(3.3英尺)深處的一根細如發(fā)絲的光纖中，每隔2米(6.5英尺)測量一次，總共有2000個傳感器。

If there is any change in the external energy on the ground above, even walking steps, you will have a very small change that's going to stretch or compress the fiber, said Tieyuan Zhu, assistant professor of geophysics at Penn State. "The laser is very sensitive and can detect these small changes."

賓夕法尼亞州立大學地球物理學助理教授Tieyuan Zhu說:“如果地面上的外部能量有任何變化，即使是步行，你也會有一個非常小的變化，它會拉伸或壓縮纖維。”“激光非常敏感，可以探測到這些微小的變化。”

During a storm such as the one in April, thunder from above smashes the ground and acoustic pressure spreads like a wave in a pond. These thunderquakes are registered and recorded, providing “yet another way to track thunderstorms and help with public safety and emergency response, especially in urban areas," said David Stensrud, co-author of the study published in the Journal of Geophysical Research: Atmospheres.

在四月的暴風雨中，從上空傳來的雷聲擊碎了地面，聲壓像池塘里的波浪一樣擴散開來。《地球物理研究雜志:大氣》(Journal of Geophysical Research:)上發(fā)表的這篇論文的作者之一戴維·斯坦斯魯?shù)?David Stensrud)說，這些雷震被記錄下來，提供了“另一種追蹤雷暴的方式，有助于公共安全和應急響應，尤其是在城市地區(qū)。”

The team identified 18 thunder-induced seismic events with peak frequencies ranging from 20 Hertz to 130 Hertz. The arrival time of the thunderquakes allowed the scientists to estimate the phase velocity of the near-surface, the back azimuth, and the path of the source as it moved from northwest to south to northeast. The location data was verified with the National Lightning Detection Network (NLDN).

研究小組確定了18個雷擊誘發(fā)的地震事件，峰值頻率從20赫茲到130赫茲不等。雷震的到達時間允許科學家們估計近地面的相位速度、反方位角和震源從西北到南到東北移動的路徑。位置數(shù)據(jù)通過國家閃電探測網(wǎng)絡(NLDN)驗證。