深山兰

地球上一种气候现象称为厄尔尼诺和拉尼娜。在正常的情况下，地球由于自转而产生的克里奥力的影响，在赤道及附近南太平洋的海面上，在从东来的信风带的吹动下，太平洋的海水往昔涌，在西太平洋的海面上集聚的水温较高。

但在厄尔尼诺发生时，赤道附近的信风减弱，海水旋转的方向改变，热水往东去，而相对对的冷水往昔去。这样，导致太平洋沿岸甚至全球的气温发生变化。

厄尔尼诺现象过去后，海水的循环方向有返回去了。返回时，有过调现象发生。这称为拉尼娜现象。

这是南太平洋海水和空气之间热量交换之间的一种振荡。气候学上称为“El Nino-Southern Oscillation (ENSO).”、地平帮们是无论如何也无法理解这种现象的！

这种现象可以类比一辆运动的车上放了一个洗澡盆。其中充满了水。在车子运动时，水会向两个方向不断振荡的，引起水面高低变化的。厄尔尼诺现象不同的是，伴随着海水高低的变化，水温是不一样的。这个水温高低的变化引起周围及更远地方的气象大变的。

1，这是1997年和2015年太平洋海水温度数据。这个温度越高，意味着厄尔尼诺越强大。就是图2中X轴上方图线越高。在历史上，意味着中国北方越极端干旱。在后面的几年内甚至导致人口大量死亡的！中国古代的黄河断流，意味着朝代要灭亡的。其实是强大的厄尔尼诺现象来临罢了。

厄尔尼诺期间，典型的影响是美洲北太平洋沿岸冬季温度高。而中国的夏季时分，南涝而北旱。

这种现象以三、五年为周期的。自然，每次的强度和表现形式都可能不同的。最近强大的厄尔尼诺现象是1997-1998年，和2015-2016年的周期。其中，2015-2016为最强大的。并且，美洲北太平洋沿岸的气象最为典型的。

1998年中国南方大水，淹得一塌糊涂的。

中国古代多次出现北方极度干旱，黄河和淮河，人都能涉水过去。把应当是强大厄尔尼诺导致的。中国古代想象的风调雨顺永远是一种梦想。太平洋的振荡永远无休止的。

地球的气候是叠加了这个振荡系统的。要搞清楚气候的真正变化的趋势，必须滤除这个振荡系统的。从数学上讲，要用高频滤波，去除这个振荡系统的影响，才能显示地球真正的气候变化的。但具有数据的 处理上，这是异常困难的工作。那种一见到某地气象变化，就大叫气候如何如何的人，简直就是天大的笑话。

气候学家们靠卫星监察太平洋海水表面的温度变化及趋势，来判断厄尔尼诺是否来临的。通常情况下，拉尼娜之后，需要一段时间，厄尔尼诺才会来临。但此次，好像是刚过去，厄尔尼诺现象有来临的趋势。这在现代的观察中，几乎没有见到过的。所以，他们没有把握厄尔尼诺会在如此短的时间内返回。他们目前仅是属于猜测而已。

下面是他们写的文章。

Return of El Niño will play a big part in summer, here's why

Dr. Doug Gillham and Michael Carter

Meteorologists

Wednesday, May 24, 2017, 6:00 -        How will a developing El Niño impact our weather this summer? Find out what you can expect for the next several months when The Weather Network releases their U.S. summer forecast on Wednesday, May 24

How do you develop a forecast for an entire season?

A seasonal forecast is very different from the day-to-day forecasts that you check to see if you need an umbrella or a jacket before heading out the door.  Seasonal forecasts cannot address the daily or even weekly details, but we seek to capture the essence of how the summer will be remembered.

The important drivers for weather patterns throughout a season seem abstract because they are things that we don’t directly experience every day, but over a three month period factors like water temperatures in the across the Pacific Ocean or air pressure patterns over Greenland can have a big impact on the type of summer we experience here in the U.S.

One of the biggest drivers of our weather on a seasonal scale from year to year is a cycle of water temperature changes that takes place in the tropical Pacific Ocean, from the coast of South America to the International Dateline. This cycle has two phases, with names that you are probably familiar with if you follow the weather regularly: El Niño and La Niña. Together they make up a larger pattern called the El Niño Southern Oscillation, or ENSO.

The strength of these two ENSO phases, and how quickly we swing between them, is one of the most important factors to analyze when creating a seasonal forecast. Although every ENSO event is unique and has its own distinct fingerprint, the current cycle stands out as particularly unusual. And because we haven’t seen this particular pattern before, it leaves us with some big questions about the upcoming summer.

What is so unique about our current weather pattern?

To answer this question we have to roll the clock back a bit, to the winter of 2015-2016. That winter was dominated by a phenomenally strong El Niño event, which at its peak intensity was equal to the “Super El Niño” of 1997-1998. The 2015-2016 El Niño was so strong that its after-effects are still influencing our weather today.

But it’s not just the strength of that El Niño that makes it so unique. Strong to very strong El Niños occur once every decade or so, and they have a well understood effect on North America’s weather. What makes the 2015-2016 event unique is what happened afterwards.

This chart shows all the big swings in the ENSO cycle going back to 1980. El Niño is the warm phase of the cycle, so El Niño events show up as sharp upward spikes on the graph. You’ll notice very prominent peaks in 2015-2016, as well as 1997-1998, ’82-’83, and several other memorable events, with weaker spikes in between.

2，在这个图上，标识厄尔尼诺的强度。X轴下方的绝对值越大意味着拉尼娜现象越强大的。在涉及到的地球各种物理特性（海水及空气）上讲，拉尼娜之后需要时间调整，才会有下一次的厄尔尼诺现象出现的。今年有打破此种限制的趋势？不得而知的。至少目前如此的。

 The downward spikes represent the cool phase of the ENSO cycle known as La Niña.  Some of the stronger La Niña events on record include 1988-1989, 1998-2000, 207-2008, and 2010-2011.

The ENSO cycle tends to swing back and forth between the warm and cold phases like a pendulum.  Typically, after a very strong warm phase we spend an extended period of time, often a couple of years or more, in the cool phase before the next warm phase begins.

Not this year though, and that’s what makes the next few months so unusual.

After the very strong El Niño of 2015-2016, we saw a very brief, weak La Niña event. It only lasted a few months, and peaked last fall.  Then during this past winter, temperatures began to warm again, as the cycle took an abrupt about-face and began to head back into El Niño territory.

This quick return to a warm pattern so soon after the last very warm event creates unique challenges for this summer’s forecast. Typically the La Niña event following a strong El Niño results in cooler ocean water temperatures across the northern hemisphere. This time, however, those cool ocean temperatures never truly got a chance to set in, and there’s still a considerable amount of lingering warmth on the map instead.

In straightforward terms, that means the normal rules don’t apply to this year’s forecast.

While the impacts of El Niño are a lot more evident during the winter, history shows us some consistent patterns during summers in which an El Niño was developing. 

However, we also have the have all that lingering warm water to consider, as temperatures hover above normal from the eastern Pacific to the Gulf of Mexico to the Gulf Stream in the western Atlantic.  This pattern tends to impact global weather patterns in a way that is opposite to what we often see with a developing El Niño. 

So, as we head into summer the drivers of our weather pattern will interact with each other in a way that we have not observed as long as reliable records of global temperatures have been kept.

In a typical seasonal forecast, we use a technique called the “analogue method”, where we look back through history to find years that had global patterns that were similar to our current pattern and study the weather that was associated with those patterns. This can give us very useful information on how the upcoming months might play out.

However, in a year this atypical, the forecast process is even more challenging as we seek to determine how the different pieces of the puzzle will fit together and interact with each other.

Please check back on May 24 for a look at our Summer 2017 forecast. At that time we will release the details on our unique summer pattern, and how it could affect you during the months of June, July, and August.