The high-tech race to improve weather forecasting, Part 2?

????????????這篇文章有點(diǎn)長，我把它分成了考研閱讀的長度（600-700words）。

????????????第一部分介紹了歐洲中期天氣預(yù)報中心的功能、極端天氣與天氣預(yù)報的重要性。

????????????????????????????在結(jié)尾用1960s至今預(yù)測準(zhǔn)確率的提升引出第二部分。

????????????第二部分介紹了天氣預(yù)測的原理及預(yù)測模型計算問題。

Cloud computing 云彩計算

1.天氣預(yù)測的原理及其依賴計算機(jī)性能的原因

Most of that improvement?has been down to?more powerful computers, says Tim Palmer, a meteorologist and physicist at the University of Oxford. Weather forecasts work by?carving the world into?a grid of three-dimensional boxes.?

Each?is populated with?temperature, air pressure, wind speed and the like, and the system’s evolution?simulated?by?grinding?through enormous numbers of calculations.

（1）be down to =depend on取決于

（2）carve (something) into (something) 把……刻進(jìn)

（3）"grid boxes"在氣象學(xué)中是指將地球表面劃分成的三維網(wǎng)格，用于氣象模型。每個格子代表一個空間區(qū)域，后文中9km、16km都是“格子”的不同規(guī)格。后文提及的"resolution"（分辨率）是指氣象模型中用于劃分網(wǎng)格的大小的級別。格子越小，分辨率越高，數(shù)據(jù)越精細(xì)，模型越精確。

（4）is populated with（=is full of）

? ? ? ??“populate”及物動詞，意為“居住”。

（5）“simulated”是過去分詞形式。

????????當(dāng)你想隨便加點(diǎn)相關(guān)信息的時候，就可以用分詞短語的結(jié)構(gòu)。

（6）grind “研磨，加工”，可以翻譯為“處理”

2.模型越精確效果越真實(shí)

Better computers allow finer models. In the same way that a?high-resolution?digital photo looks more realistic than a?coarse-grained?one, using a smaller grid helps match a model more closely to the real world.?

The ECMWF’s highest-resolution global model, for instance, chops the globe into boxes that are 9km square, down from 16km in 2016, and splits the atmosphere vertically into more than 100 layers.

high-resolution 高分辨率的

coarse-grained 粗糙的

3.小網(wǎng)格的作用

Smaller grids also allow models to recreate more of what happens in the real weather. “Deep?convective clouds”, for instance, are formed as hot air floats upwards. They can produce heavy rain, hail and even tornadoes, but typically cannot be resolved with grids bigger than about 5km.

Models have instead represented them using?stopgap code?that acts as a simplified substitution.

convective cloud?對流云
stopgap 應(yīng)急的

stopgap code指編程中不夠理想的代碼

4.精確度與局域性，有錢才能全都要

But smaller grids come at a high price.?Halving?the horizontal size of a grid means that four times as many boxes—and four times as many calculations—are needed to cover a given area. One option is to trade resolution for locality.?

The sharpest?offering from the National Oceanic and Atmospheric Administration, in America, for instance, uses grid boxes 3km square, but covers only North America. Computing, meanwhile, continues to improve.?

The world’s fastest computer is Frontier, installed at Oak Ridge National Laboratory in Tennessee. Using it, ECMWF scientists were able to experiment with running a worldwide model with a 1km resolution.

halve 把……分成兩半

the sharpest in America 美國最精確的模型

5.混沌系統(tǒng)之限，無關(guān)技術(shù)能力

But no matter how powerful computers become, there is a limit to how far ahead a numerical forecast can look. The atmosphere is what mathematicians call a “chaotic system”—one that is exquisitely sensitive to its?starting conditions.?

A tiny initial change in temperature or pressure can compound over days into drastically different sorts of weather. Since no measurement can be perfectly accurate, this is a problem that no amount of computing power can solve.

In 2019 American and European scientists found that even the most minor alterations to simulations resulted in highly divergent forecasts for day-to-day weather after about 15 days.?

“It seems to be a limit that nature sets,” explains Falko Judt, a meteorologist at the National Centre for Atmospheric Research, in America. “It has nothing to do with our technological capabilities.”

"Starting conditions"（初始條件）是指在數(shù)值模型（numerical forecast）中用來啟動模擬或預(yù)測的初始狀態(tài)，非常依賴準(zhǔn)確的數(shù)據(jù)。

歡迎指正，感謝閱讀。