• Climate Change and Climate Modeling
  • Chapter 4 El Niño and year-to-year climate prediction
  • 英文词句摘录

明天就要回家了，今天是在学校的最后一天，估摸着回家后可能会有兴致画图，但不一定会有兴趣看书，因此趁着这最后的安宁，赶紧再看几页英文书。

Climate Change and Climate Modeling

Chapter 4 El Niño and year-to-year climate prediction

这一章主要介绍目前关于ENSO维持机制和转变机制的各种猜想，随后介绍ENSO的遥相关。

目前只看到前半部分，了解到关于次表层海洋动力学的内容以及海洋观测仪器。

作者说到，东太平洋的温跃层较浅，故上升流可使其表面温度变得较冷。若其温跃层同西太平洋一样深厚，那么上升流对海表温度SST的影响就不会那么大。

在温跃层较深厚的地方，该地方的海表高度和海水压强都比较强。

在赤道太平洋，海表受风应力的影响，海水向西流动，在次表层，受到海水压强梯度的作用，海水向东流动。

在Ei-Nino发生之前，西太平洋的海面高度会异常升高。

在向EINino转变时，深厚的温跃层从赤道太平洋西部向东部传播。当太平洋东部的温跃层也变深厚后，在上升流的影响下时太平洋东部海温升高，进而激发 Bjerknes feedbacks 。随后该反馈进一步使太平洋西部的温跃层变浅，这也是EINino向LaNina转变的一个信号，因为随后太平洋西部的这一浅温跃层又会向太平洋东部传播。

但并不是所有强EINino事件后都会发生强LaNina事件。ENSO循环的这种不规则性可能受到天气事件的影响。

海洋的观测仪器有：1、固定的浮标；2、检测海表面风速的游动浮标；3、由巡航船只丢入海中的深海温度探测器；4、岛屿雨量筒；5、卫星。

卫星的成本似乎比固定浮标的成本低。因为卫星虽然研发和发射成本高，但随后可以提供多年海洋数据，而浮标除前期研发和安装要钱外，每年还需要支付大笔的维修费。

英文词句摘录

the essential features of sth

the mechanisms for maintaining a fully developed El Niño (warm) or La Niña (cold) phase

While the heart of ENSO lies in the tropical Pacific, impacts in other parts of the world are also important. Such remote effects of El Niño or La Niña are termed teleconnections.

During the 1980s and 1990s many investigators contributed to making this conjecture a full fledged theory.

In essence, ENSO arises as a coupled cycle in which anomalies of SST in the Pacific cause the trade winds to strengthen or slacken, and this in turn drives the ocean circulation changes that produce anomalous SST.

As we shall see, the dynamics of “how the turnabout” takes place involves subsurface ocean dynamics.

the trade winds blowing from east to west across the Pacific

Surface currents exactly on the equator tend to flow westward, accelerated by the wind stress on the ocean surface due to frictional effects.

While we often show anomalies for these conditions, it is useful to remember what the total fields look like.

In terms of anomalies, this corresponds to a westerly anomaly, even though the total winds may still be easterly.

Initial success in the Pacific led to subsequent deployment of similar buoys in the Atlantic, and ongoing deployment in the Indian Ocean. The observations are transmitted via satellite to data centers, where they are compiled and made available to researchers and forecast centers almost immediately.

The depression of the thermocline extends slowly from west to east along the equator.

Basically the cold anomalies along and off the equator in the west are a La Niña waiting to happen. This allowed model predictions of the 1998–99 La Niña, just as the subsurface warm anomalies allowed predictions of the preceding El Niño.

On the oceanic side

It is also worth noting that the succession between El Niño and La Niña is not always so rapid and can be more complex than the example provided by the 1998 case.