70% probability! US NOAA authority forecast: El Nino or upcoming in autumn and winter

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70% probability! US NOAA authority forecast: El Nino or upcoming in autumn and winter

2018-09-20 00:25:28 1179 ℃

Recently, researchers at the National Oceanic and Atmospheric Administration (NOAA) have turned their attention to the distant tropical Pacific. The changes here are worthy of the attention of scientists: although the tropical Pacific is currently in a neutral condition that is neither La Nina nor El Niño, But scientists point out that the El Niño phenomenon will come later in the fall of 2018, with a probability of about 50-55%. In the winter, the possibility of the El Niño phenomenon increases to about 65-70%.

According to the analysis report given by NOAA, the tropical Pacific region currently looks very neutral. The main indicator of the El Niño 3.4 sea area is slightly higher than the average temperature by 0.3 degrees Celsius. In fact, most of the surface waters in the equatorial Pacific are slightly higher than the average for the same period of the previous year, while the East Pacific has recently appeared slightly lower. Area. At the same time, scientists have also discovered that the atmosphere pattern of the Pacific Ocean is also rapidly changing, and the last traces of the cloud and rain patterns of the La Niña phenomenon in the tropical Pacific have disappeared for several months. During August, the average cloud cover in most tropical Pacific regions was close to average.

The remarkable La Niña phenomenon that occurred in late 2017 to early 2018 can be said to be officially announced, and most climate models It is predicted that the autumn sea surface temperature in the tropical Middle East and Pacific will exceed the El Niño threshold, which is more than 0.5 degrees above the long-term average. This warming prediction is a major factor that scientists believe is likely to occur in the El Niño phenomenon in the coming months.

These predictions are not without foundation. There are several physical factors that support scientists' predictions, such as the rising seawater heat content beneath the surface of the equatorial Pacific, which measures the surface of the Pacific waters. And extra heat between about 300 meters in depth. At the beginning of August, some changes in the wind over the tropical Pacific Ocean intensified a large warm submerged sink that gradually tilted eastward under the surface of the equatorial Pacific Ocean. As the warm water gradually moves eastward, the warm seawater will gradually rise, which will increase the warming of the surface in the next few months.

NOAA scientists are also concerned about the winds of the tropical Pacific Ocean as they are an important part of the evolution of water temperature throughout the tropical Pacific. . On average, trade winds in the tropical Pacific Ocean steadily blow from east to west along the equator, cooling the surface of the eastern Pacific Ocean and pushing warm water to the west. When the wind mode changes, the ocean changes. Research around the wind is one of the more complex projects in meteorology and climatology. Since the trade winds in the equatorial region usually blow from the east, they are called Dongfeng. When the east wind slows down, we call this change an anomaly of westerly winds. If they are unusually strong, they are sometimes referred to as "westerly events" or "westerly outbreaks." But in fact, very few trade winds can really reverse the direction - usually only during the strong El Niño phenomenon like 1997-1998 or 2015-2016. But just weakening the east wind is enough to change the cycle in the ocean. In the past few months, scientists from NOAA have seen westerly anomalies in the equatorial Pacific, including the intensification of warm winds in early August. Although this anomaly is not particularly dramatic, it is sufficient to support the prediction of the El Niño phenomenon.

NOAA scientists also conducted some analysis of the timing of the El Niño phenomenon, which pointed out that in recent decades The El Niño phenomenon has been inclined to the second half. This is also one of the reasons for predicting the greater likelihood of El Niño in winter.

But there are exceptions. The example given by NOAA is 2014. The surface of the tropical Pacific Ocean is indeed warming and large. Part of the time is above the threshold of the El Niño phenomenon, that is, the surface of the seawater in winter is above the average of 0.5 degrees. However, the atmospheric response of the El Niño phenomenon did not begin until the spring of the second year, 2015. It is not impossible for this edge to happen again. However, NOAA's current forecast still believes that from the current evolutionary situation, changes in wind and seawater in the Pacific region are conducive to the formation of the El Niño phenomenon this autumn and winter, thus producing more weather for the second half of the year and the first half of 2019. Many variables.