This constant westward forcing results in a sea level in the West Pacific off South East Asia that is up to 60 centimetres higher than that off the western coast of South America. Replacing the surface water pushed westward away from the South American coast by the trade winds, cold, nutrient-rich water from below flows upward to the surface. This phenomenon is called upwelling.
But as it moves westward it is constantly heating up, until the water masses finally reach a temperature of around 30 degrees Celsius off the South East Asian coast. Because of the heat, large amounts of the water evaporate off South East Asia, forming intense cloudiness and resulting in the development of a warm tropical rainforest climate.
The other circulation system, the Walker Circulation, only occurs in the Pacific. It flows in an east-west direction, at right angles to the Hadley Circulation. This circulation, named after its discoverer, the English physicist Gilbert Walker, is driven by atmospheric pressure differences between the western and central Pacific.
As a rule, there is a stable low-pressure system above the western Pacific near South East Asia and a high-pressure system in the central Pacific. This results in a constant westward flow of the air masses from the area of high pressure to the area of low pressure.
Heating of the land in the summer and cooling of the land in the winter sets up land-sea temperature contrasts that affect the atmospheric circulation over the neighboring ocean. This land influence competes with ocean and atmosphere interactions which are essential for generating ENSO.
They also publish a monthly Climate Diagnostics Bulletin. The Climate Analysis Center at the U. National Center for Environmental Prediction provides up to date Regional Climate Monitoring information from many parts of the world. A variety of indices are used to characterize ENSO because it effects so many elements of the atmosphere-ocean climate system.
The measurements needed for these indices are straightforward, and we have long historical records, especially for the the SOI. However, other indices are effective at characterizing other aspects of ENSO.
For example, the anomalous mb zonal winds show how the low-level atmospheric flow is responding to low-level pressure anomalies associated with ENSO and other mechanisms. Often the mb flow about 1. An index involving the mb zonal flow is used to describe the upper tropospheric winds, whose anomalies tend to be opposite to those at mb and below. The mb flow is particularly important because it is changes at around this level in the tropics that tend to have the biggest consequences for the atmospheric circulation outside of the tropics.
The mb temperature represents a proxy for the anomalous heat content of the tropical troposphere. In an overall sense, there is greater heating of the troposphere, and more deep cumulus convection, than normal during warm ENSO events El Ninos. Finally, there is one more widely used index for the atmosphere and that relates to the outgoing longwave radiation or OLR. The deeper the cumulus convection, the colder the cloud tops, which means the thermal or infrared radiation to space is reduced.
It is straightforward to monitor OLR via satellite; its value in the tropical Pacific near the dateline is an effective way to gauge the frequency and magnitude of the thunderstorm activity that changes with ENSO.
Current values of these indices provided on-line by the Climate Prediction Center. In general, warm ENSO episodes are characterized by an increased number of tropical storms and hurricanes in the eastern Pacific and a decrease in the Gulf of Mexico and the Caribbean Sea.
Tropical weather products pages are available from the University of Michigan and from the University of Hawaii. The world expert in this area of study is Prof. Bill Gray of Colorado State University. See the latest articles on this topic from climate. Coral bleaching results when sea temperature rises above a threshold about 28C beyond which corals expel colorful symbiotic algae hence the bleaching.
Deprived of metabolic by-products generated by algae for extended periods, corals die. We don't know the answer to this question. However, computer climate models, one of the primary research tools for studies of global warming, are hampered by inadequate representation of many key physical processes such as the effects of clouds on climate and the role of the ocean.
So, depending on which model you choose to believe, you can get different answers. This is a very complicated but very important! What influences what? This second question ties into the first question above. Might cacophony be a good image to describe circulation patterns? That's a nice analogy. However, it could be refined in the following way: when the scores are played together, they not only become entangled, but they may actually metamorphose into a slightly different tune, one for which no score existed at the start of the piece.
Sorting out these complex interactions is in fact one of the major challenges of climate research today. Conservation of angular momentum is a basic physical principal which operates, for example, when a ballerina brings her arms closer to her body to spin faster. There are 86, seconds in a day, so this change represents one part in million. Such a change will have little effect on normal activities on a human scale, such as flying an airplane.
That's a lot of ice, and there's no way to extract and transport that amount of ice with existing technology. Furthermore, it would take a long time to transport. It would be too late to do any good. Finally, the extraction of that much ice would seriously damage the environment of Antarctica.
It could also have potentially serious consequences on global climate if it lead to changes in surface reflection of sunlight, or had other effects on land surface processes.
Many computer models correctly forecast that would be unusually warm in the tropical Pacific. That was a major advance by any measure, because just knowing that the tropical Pacific will be warm or cold a season or two in advance provides great leverage in making more reliable long range weather forecasts around the globe. The seasonal forecast for wintertime conditions, based in large part on the evolving temperatures in the tropical Pacific captured many of the large scale patterns of temperature and precipitation of the continental US.
In the Pacific Northwest, for example, the three month period November - January was the wettest on record. Meanwhile, an increase in sinking air motion over Indonesia leads to higher surface pressure and dryness. NOAA Climate. The surface winds across the entire tropical Pacific are stronger than usual, and most of the tropical Pacific Ocean is cooler than average. Rainfall increases over Indonesia where waters remain warm and decreases over the central tropical Pacific which is cool.
Over Indonesia, there is more rising air motion and lower surface pressure. There is more sinking air motion over the cooler waters of the central and eastern Pacific. Anomalous ocean cooling blue-green in the central and eastern Pacific Ocean and warming over the western Pacific Ocean enhance the rising branch of the Walker circulation over the Maritime Continent and the sinking branch over the eastern Pacific Ocean.
Enhanced rising motion is also observed over northern South America, while anomalous sinking motion is found over eastern Africa. Convection associated with rising branches of the Walker Circulation is found over the Maritime continent, northern South America, and eastern Africa.
Instead, the warmer tropical Pacific waters cause changes to the global atmospheric circulation , resulting in a wide range of changes to global weather. Think of how a big construction project across town can change the flow of traffic near your house, with people being re-routed, side roads taking more traffic, and normal exits and on-ramps closed.
Different neighborhoods will be affected most at different times of the day. That isn't an answerable question. Think of it this way: Suppose that in an average year, your state experiences 10 winter storms. It's impossible to say which 10 were your "normal" ones and which 3 were the "extra" ones. This sort of analysis is called an attribution study.
It requires comprehensive observations—both current and historical—as well as highly detailed climate recreations of the weather patterns that gave rise to the storm. It may take scientists several months to conduct this kind of analysis.
This shift disrupts the atmospheric circulation patterns that connect the tropics with the middle latitudes, which in turn modifies the mid-latitude jet streams. By modifying the jet streams, ENSO can affect temperature and precipitation across the United States and other parts of the world. The influence on the U.
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