The bottom panel of the December plot shows anomalies, the way the sea surface temperature and wind differs from a normal December. In December , the warm water right column of images, red in the top panel of the December plot has spread from the western Pacific Ocean towards the east in the direction of South America , the "cold tongue" right column of images, green color in the top panel of the December plot has weakened, and the winds in the western Pacific, usually weak, are blowing strongly towards the east, pushing the warm water eastward.
The anomalies show clearly that the water in the center of Pacific Ocean is much warmer red than in a normal December. This name was used for the tendency of the phenomenon to arrive around Christmas. The bottom panel in the animations, labeled anomalies, shows temperature deviations from normal how much the sea surface temperature is different from the long term average. The red color in the anomalies plot indicates that the temperature of the water is much warmer than is normal for that month, whereas blue color indicates that the water is much cooler than is normal.
In the left hand panel of the graphic below, you see the sea surface temperature at the Equator in the Pacific Ocean Indonesia is towards the left, South America is towards the right. Time is increasing downwards from at the top of the plot, to the present, at the bottom of the plot.
NOTE: Click to see a larger version of this annotated graphic or a larger, realtime version of this graphic with the latest data.
Sea surface temperatures left panel : The first thing to note is the blue "scallops" on the right of the plot, in the eastern Pacific. This allows great masses of warm water to slosh from the western Pacific toward the Americas. It also reduces the upwelling of cooler, nutrient-rich waters from the deep—shutting down or reversing ocean currents along the equator and along the west coast of South and Central America.
The circulation of the air above the tropical Pacific Ocean responds to this tremendous redistribution of ocean heat. The typically strong high-pressure systems of the eastern Pacific weaken, thus changing the balance of atmospheric pressure across the eastern, central, and western Pacific.
While easterly winds tend to be dry and steady, Pacific westerlies tend to come in bursts of warmer, moister air. Because of the vastness of the Pacific basin—covering one-third of the planet—these wind and humidity changes get transmitted around the world, disrupting circulation patterns such as jet streams strong upper-level winds.
What we don't know is what triggers the shift. This remains a scientific mystery. The changing ocean conditions disrupt weather patterns and marine fisheries along the west coasts of the Americas. Dry regions of Peru, Chile, Mexico, and the southwestern United States are often deluged with rain and snow, and barren deserts have been known to explode in flowers. Meanwhile, wetter regions of the Brazilian Amazon and the northeastern United States often plunge into months-long droughts.
From underwater floats that measure conditions in the depths of the Pacific to satellites that observe sea surface heights and the winds high above it, scientists now have many tools to dissect this l'enfant terrible of weather. The ocean is not uniform. Temperatures, salinity, and other characteristics vary in three dimensions, from north to south, east to west, and from the surface to the depths. With its own forms of underwater weather, the seas have fronts and circulation patterns that move heat and nutrients around ocean basins.
Changes near the surface often start with changes in the depths. The tropical Pacific receives more sunlight than any other region on Earth, and much of this energy is stored in the ocean as heat. Under neutral, normal conditions, the waters off southeast Asia and Australia are warmer and sea level stands higher than in the eastern Pacific; this warm water is pushed west and held there by easterly trade winds.
This mass, referred to as the "western Pacific warm pool," extends down to about meters in depth, a phenomenon that can be observed by moored or floating instruments in the ocean: satellite-tracked drifting buoys, moorings, gliders , and Argo floats that cycle from the ocean surface to great depths.
These in situ instruments more than 3, of them record temperatures and other traits in the top meters of the global ocean. The visualization above shows a cross-section of the Pacific Ocean from January through December It shows temperature anomalies; that is, how much the temperatures at the surface and in the depths ranged above or below the long-term averages. Note the warm water in the depths starting to move from west to east after March and peaking near the end of The western Pacific grows cooler than normal.
For hundreds of years, the temperature near the water surface has been measured by instruments on ships, moorings and, more recently, drifters. Since the late s, satellites have provided a global view of ocean surface temperatures , filling in the gaps between those singular points where floating measurements can be made. Sea surface temperatures are measured from space by radiometers , which detect the electromagnetic energy mostly light and heat emitted by objects and surfaces on Earth.
The maps above show sea surface temperature anomalies in the Pacific from winter and fall of The maps do not depict absolute temperatures; instead, they show how much above red or below blue the surface water temperatures were compared to a long-term year average. In and , sea surface temperatures rose more than 2.
Sea level is naturally higher in the western Pacific; in fact, it is normally about 40 to 50 centimeters inches higher near Indonesia than off of Ecuador. Some of this difference is due to tropical trade winds, which predominantly blow from east to west across the Pacific Ocean, piling up water near Asia and Oceania.
Some of it is also due to the heat stored in the water, so measuring the height of the sea surface is a good proxy for measuring the heat content of the water. Water expands as it warms, causing the surface of the ocean to rise. It shows sea surface height anomalies, or how much the water stood above or below its normal sea level. Shades of red indicate where the ocean was higher because warmer water expands to fill more volume thermal expansion. Shades of blue show where sea level and temperatures were lower than average water contraction.
Countries like the U. Forecasting can help such vulnerable societies prepare for these impacts. Places that see more rain could see negative as well as positive impacts. A little rain can be helpful in places like southeastern South America, but too much can expose crops to disease. Researching and reporting the science and impacts of climate change. Who We Are An independent organization of leading scientists and journalists researching and reporting the facts about our changing climate and its impact on the public.
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Nutrients in the cold water include nitrate s and phosphate s. Tiny organisms called phytoplankton use them for photosynthesis , the process that creates chemical energy from sunlight. Other organisms, such as clams, eat the plankton, while predator s like fish or marine mammal s prey on clams. Upwelling provides food for a wide variety of marine life, including most major fisheries. Fishing is one of the primary industries of Peru, Ecuador, and Chile.
Some of the fisheries include anchovy, sardine, mackerel, shrimp, tuna, and hake. The upwelling process also influences global climate. The warm ocean temperature in the western Pacific contributes to increased rainfall around the islands of Indonesia and New Guinea.
The air influenced by the cool eastern Pacific, along the coast of South America, remains relatively dry. Teleconnection s are large-scale, long-lasting climate anomalies or patterns that are related to each other and can affect much of the globe. These changes in air pressure and wind speed cause warm surface water to move eastward along the Equator, from the western Pacific to the coast of northern South America.
These warm surface waters deepen the thermocline , the level of ocean depth that separates warm surface water from the colder water below. This thick layer of warm water does not allow normal upwelling to occur. Without an upwelling of nutrient-rich cold water, the euphotic zone of the eastern Pacific can no longer support its normally productive coastal ecosystem.
Fish populations die or migrate. Convection above warmer surface waters bring increased precipitation. Rainfall increases drastically in Ecuador and northern Peru, contributing to coastal flooding and erosion.
Rains and flood s may destroy homes, schools, hospitals, and businesses. They also limit transportation and destroy crop s. Agriculture , which depends on water for irrigation , is threatened.
Global atmospheric circulation is the large-scale movement of air that helps distribute thermal energy heat across the surface of the Earth. The eastward movement of oceanic and atmospheric heat sources cause unusually severe winter weather at the higher latitude s of North and South America.
Regions as far north as the U. These strong temperature increases caused severe climatic changes: Australia experienced harsh drought conditions; typhoon s occurred in Tahiti; and record rainfall and flooding hit central Chile. The west coast of North America was unusually stormy during the winter season, and fish catches were dramatically reduced from Chile to Alaska.
The event produced drought conditions in Indonesia, Malaysia, and the Philippines.
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