- 記錄人類文明的那些美文（環球時代美文讀本）
- 吳中東 宮玉波
- 1683字
- 2020-08-20 09:57:22
09 El Nino
海洋氣學：介紹預測厄爾尼諾海流的數學模型
導讀
厄爾尼諾（El Nino）是在太平洋的秘魯和厄瓜多爾沿岸圣誕節前后發生的一種海水溫度異常升高的現象。這是一種大規模的海洋和大氣相互作用的現象。本文從海洋氣學的角度介紹了預測厄爾·尼諾海流的數學模型。
The recent, apparently successful, prediction
by mathematical models of an appearance of El Nino—the warm ocean current that periodically develops along the Pacific coast of South America—has excited researchers. Jacob Bjerknes pointed out over 20 years ago how winds might create either abnormally warm or abnormally cold water in the eastern equatorial Pacific. Nonetheless, until the development of the models no one could explain why conditions should regularly shift from one to the other, as happens in the periodic oscillations between appearances of the warm El Nino and the cold called anti El Nino. The answer, at least if the current model that links the behavior of the ocean to that of the atmosphere is correct, is to be found in the ocean.
It has long been known that during an El Nino, two conditions exist: (1) unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and (2) winds blow from the west into the warmer air rising over the warm water in the east. These winds tend to create a feedback mechanism by driving the warmer surface water into a “pile” that blocks the normal upwelling of deeper, cold water in the east and further warms the eastern water, thus strengthening the wind still more. The contribution of the model is to show that the winds of an El Nino, which raise sea level in the east, simultaneously send a signal to the west lowering sea level. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level, that moves westward parallel to the equator at 25 to 85 kilometers per day. Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as the Philippines and Indonesia.
最近，用數學模型對厄爾尼諾海流（沿南美洲太平洋海岸周期產生的暖洋流）的出現進行顯然成功的預報，大大激勵了氣象研究工作者。雅各布·畢爾克內斯在二十多年前就已經指出，風如何可能在東部赤道附近的太平洋洋域中造成反常的暖水流或者反常的冷水流。然而，直到研究出這個數學模型，人們才有可能解釋為什么竟然是從一種狀態有規則地轉變到另一種狀態。這種情況發生在暖厄爾尼諾海流和所謂反（冷）厄爾尼諾海流周期交替出現的時候。問題的答案可以從海洋中找到，至少假如當前聯系海洋變化同大氣變化的模式是正確的話。
長期以來，氣象研究工作者都知道：在發生厄爾尼諾現象期間，存在著兩個條件：第一，異常暖和的水流沿東太平洋，主要是沿厄瓜多爾和秘魯海岸擴展；第二，從西方吹來的風，吹進東方暖水流上空升起的更加暖和的氣流中。這些風把洋面較暖和的水流聚成“一堆”，阻止東部深海冷水流正常地向上涌出，使得東部水域更加暖和，因而更加加強了這股風的力量，這樣有助于造成一個反饋機制。這個模型的貢獻是要表明：厄爾尼諾海流的風提高東部的海平面，同時給西方降低的海平面輸送一個信號。按照這個模型，這個信號是作為負羅斯比波而產生。負羅斯比波是壓低的或負的海平面波，以每天25到85千米的速度平行于赤道向西運動。羅斯比波花費數月的時間橫越太平洋，行進到太平洋盆地的西部邊界。這個邊界在模型被看做是平滑的墻，但事實上是由諸如菲律賓群島和印度尼西亞群島這樣很不規則的島嶼鏈組成的。
Sentence Translation
句子翻譯
1. Nonetheless, until the development of the models no one could explain why conditions should regularly shift from one to the other, as happens in the periodic oscillations between appearances of the warm El Nino and the cold called anti El Nino.
2. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level, that moves westward parallel to the equator at 25 to 85 kilometers per day.
Key
1．然而，直到研究出這個數學模型，人們才有可能解釋，為什么竟然是從一種狀態有規則地轉變到另一種狀態。這種情況發生在暖厄爾尼諾海流和所謂反（冷）厄爾尼諾海流周期交替出現的時候。
2．按照這個模型，這個信號是作為負羅斯比波而產生。負羅斯比波是壓低的或負的海平面波，以每天25到85千米的速度平行于赤道向西運動。
Emulation
美文自己寫得出——學生仿寫
仿寫范例
Should Pets Be Treated as Family Members?
Throughout history, animals have always been great companions to man. Today, we treat our pets as members of family, playing with them and nursing them when they are sick, and I believe that the relationships that people have with their pets are healthy for many reasons.
Firstly, animals provide companionship for people who are too old to maintain regular friendship. It is most common for one spouse to outlive the other. Frequently, the surviving spouse does not remarry, and eventually, all his or her friends die. When one is elderly, it is difficult to make new friends. In this type of situation, having a pet as a companion is greatly preferable to spending all of one's time alone. While a pet cannot speak, it can understand its master's emotions, and usually responds accordingly.
Secondly, animals have been proven to reduce their master's stress. This is probably because an animal is always happy to see its master, and gives the master unconditional love. As long as the master is kind to his/her pet, the pet will be devoted and faithful. A pet also provides a friendly face after a stressful day. For example, I have a pet dog. After taking an exam, the only thing I want to do is to go home and play with my dog. He always brings me much needed cheer and happiness.
Lastly, having an animal can prepare a young couple for children. A young animal is very difficult to take care of. Let us take the example of a puppy. One can never leave a puppy by itself. A puppy must be constantly taken care of; he must be toilet-trained and disciplined. Raising an animal can make one happy and sociable very much like raising a child to possess the same attributes. While a puppy is obviously easier to take care of than a child, it can show the prospective parents where some of the difficulties will lie when raising a baby.
In conclusion, I think having a very close relationship with a pet is healthy. Having a pet can reduce loneliness, stress, and prepare one for the huge experience of having a child. Pets are often referred to as man's best friend, and for good reason.