46 El Niño and La Niña-Mid

El Niño and La Niña FOCUS Question How does water in the Pacific Ocean impact climates around the world?

El Niño和La Niña焦点问题太平洋的水如何影响世界各地的气候?

The Ocean/Air Connection The Pacific Ocean is the largest body of water on Earth. The heat and energy stored within its waters are so great that this vast ocean affects climates around the globe. Energy in the form of heat is transferred from the ocean to the atmosphere and from the atmosphere back to the ocean. These cycles of heat transfer work together like the gears of a machine to create global climate patterns. In turn these patterns create weather events such as droughts or flooding that affect countries surrounding the Pacific Ocean. One important pattern in the Pacific Ocean is the El Niño-Southern Oscillation (ENSO).

海洋和空中的联系太平洋是地球上最大的水域。 它的水域中储存的热量和能量是如此巨大，以至于这片广阔的海洋影响着全球的气候。 能量以热的形式从海洋转移到大气，再从大气转移回海洋。 这些热传递的循环就像一台机器的齿轮一样共同作用，创造了全球气候模式。 反过来，这些模式又造成了影响太平洋周边国家的干旱或洪水等天气事件。 太平洋的一个重要模式是El Niño-Southern涛动(ENSO)。

The ENSO is a natural climate cycle that moves heat energy throughout the ocean and between the ocean and the atmosphere. This exchange of heat happens deep underwater, at the surface of the water, and in the atmosphere above the ocean. The ENSO cycle is made up of three parts, or phases: the neutral phase, the El Niño phase, and the La Niña phase. One phase leads into another. About half the time, the Pacific Ocean is in the neutral phase. This is the part of the ENSO cycle that scientists consider the normal conditions of the Pacific Ocean. Word Wise To oscillate means to move back and forth between two points, like some electric fans do. In ENSO, it means to move between the El Niño and La Niña phases.

ENSO是一种自然的气候循环，热量在海洋中以及海洋和大气之间流动。 这种热交换发生在水下深处，在水面上，在海洋上方的大气中。 ENSO周期由三个部分或阶段组成:中性阶段、El Niño阶段和La Niña阶段。 一个阶段引出另一个阶段。 大约有一半的时间，太平洋处于中性阶段。 这是ENSO循环的一部分，科学家认为这是太平洋的正常情况。 振荡的意思是在两点之间来回移动，就像一些电风扇一样。 在ENSO中，它意味着在El Niño和La Niña相之间移动。

Neutral Phase Across our planet, air moves from areas of high pressure, to areas of low pressure which creates wind. The equator is an area of low pressure, so wind moves toward it from both the Northern and Southern Hemispheres. Due to Earth's rotation, winds arriving at the equator move from east to west (see diagram). They are called trade winds. Across the Pacific Ocean, trade winds move warm water at the ocean's surface from east to west. The zone between warmer surface water and colder deep-ocean water is called the thermocline (see page 5). As the surface water moves west, deeper, cooler water comes up to take its place. This upwelling creates clear differences, in water temperature, with cooler water off the coast of South America and warmer water near Australia.

在我们的星球上，空气从高压地区移动到低压地区，从而产生风。 赤道是一个低压区，所以风从南北半球都向赤道移动。 由于地球的自转，到达赤道的风从东向西移动(见图表)。 它们被称为信风。 在太平洋上，信风将海洋表面的温水从东向西移动。 温暖的地表水和寒冷的深海水之间的区域被称为温跃层(见第5页)。 当地表水向西移动时，更深、更冷的水上来取代它的位置。 这种上升流在水温上造成了明显的差异，南美洲海岸的水温较低，而澳大利亚附近的水温较高。

When the warm surface water reaches land in the western Pacific, the heat energy within the ocean is transferred to the atmosphere. Warm, moist air rises from the ocean, creating thunderstorms. After the heavy rainfall, the air becomes drier and cooler. This dry, cool air moves back toward the east where it sinks and joins the trade winds again. This cycle of air movement in the atmosphere is called the Walker Circulation. The Walker Circulation is driven by convection—the movement of heat through air or water. A convection cycle also occurs underwater as warm surface water. moves west and cold, deep water rises up to take its place.

当温暖的地表水到达西太平洋的陆地时，海洋中的热能就被转移到大气中。 温暖潮湿的空气从海洋上升，形成雷暴。 大雨过后，空气变得干燥而凉爽。 干燥、凉爽的空气回到东部，在那里下沉并再次加入信风。 这种大气中空气运动的循环被称为沃克环流。 沃克环流是由对流驱动的，即热量通过空气或水的运动。 对流循环也发生在水下，如温暖的地表水。 向西移动，冰冷的深水上升取代了它。

El Niño Phase When cool water off the coast of South America is replaced by warm water, an El Niño phase begins. The atmosphere and ocean work together to form an area of warmer-than-normal water in the Pacific. The Walker Circulation weakens or even reverses. Less cool dry air sinks in the eastern Pacific. The trade winds also weaken. Now, warm surface water builds up near South America. This warm water blocks the upwelling of cold water, making the surface water even warmer. With warm water now centered in the eastern Pacific, rain clouds form farther east and bring more rain to Central and North America.

El Niño阶段当南美洲海岸的冷水被温水取代时，El Niño阶段开始。 大气和海洋共同作用，在太平洋形成了一个比正常水域更温暖的区域。 沃克环流减弱甚至逆转。 在东太平洋，较少的凉爽干燥空气下沉。 信风也减弱了。 现在，温暖的地表水在南美洲附近聚集。 这些温水阻挡了冷水的上涌，使得地表水更加温暖。 温暖的海水现在集中在太平洋东部，雨云在更远的东部形成，给中美和北美带来更多的降雨。