Do you want to know...
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1. Three main factors that affect climate variability
2. Why ENSO is valuable to know |
Weather is consist of temperature, humidity, and clouds
If you have some interest on your weather, you surely have seen that there’s some patterns in the weather
The big flood is not the every-year event
Drought comes once in several years
Not every winter we meet heavy snow continued more than 5 days
Scientists are also curious about what you think now!
They thought that there’s some wave on the climate.
Each wave have their own period and amplitude
And because of their different time periods, they make various combination on weather.
Below are the three main waves that affect global periodic atmospheric events.
AO
(Arctic Oscillation) |
ENSO
(El Niño-Southern Oscillation) |
QBO
(Quasi-Biennial Oscillation) |
AO (Arctic Osciallation)
is defined as the difference in the sea level pressure (SLP) between the northern hemispheric mid-latitudes and the Arctic.
Well.. This is the academic definition. The important thing is that it primarily affects on tropospheric temperature variability in the mid-latitude(30-60N)
For your easier understanding, I will tell you what will occur when AO index is in positive or negative phase. When the AO index is positive, surface pressure is low in the polar region. This helps the middle latitude jet stream to blow strongly and consistently from west to east, thus keeping cold Arctic air locked in the polar region. When the AO index is negative, there tends to be high pressure in the polar region, weaker zonal winds, and greater movement of frigid polar air into middle latitudes.
Below is the new report about AO,
"Cold arctic air gripped western Europe in the first three weeks of December. Two major snowstorms, icy conditions, and frigid temperatures wreaked havoc across much of the region...The harsh winter weather was attributed to a negative Arctic Oscillation, which is a climate pattern that influences weather in the Northern Hemisphere. A very persistent, strong ridge of high pressure, or 'blocking system', near Greenland allowed cold Arctic air to slide south into Europe. Europe was not the only region in the Northern Hemisphere affected by the Arctic Oscillation...." [State of the climate, Dec 2010]
ENSO (El Niño-Sourthern Oscillation)
is defined as a coupled ocean-atmosphere phenomenon influencing tropical and extra-tropical regions though atmospheric oscillations and teleconnections.
The phenomena are found to have a significant impact on the tropospheric and the low stratosphere temperature variability over the tropics and are consistent with the zonal-wind meridional circulations.
The results of this oscillation, there’s El Niño and La nina at the Pacific Ocean.
For the further understanding, you should check “Definition tab”!!
QBO (Quasi-Biennial Oscillation) is defined as an interannual oscillation of the zonal wind s and temperatures in the tropical stratosphere with a variable period averaging approximately 28 months QBO has impacts on low stratospheric temperature and modulate the stratospheric flow from pole to pole |
Time-height of monthly-mean equatorial zonal wind(u) in m/s about 20 and 35 km altitude above sea level over a ten-year period. Red color means westerly and blue one means easterly.
Radiosondes data showing the Quasi-biennial oscillation of the stratospheric wind direction near the Equator : by Morn. Graph made using data from FU Berlin.
Then..
WHY WE SHOULD KNOW ABOUT ENSO?
In these days, there are more natural disasters than past century and they result in huge scale of damage on human life and properties.
Studies are needed for the prediction on when these disaster occurs, how large it will be, and why it occurs.
We choose the atmospheric wave, especially ENSO for the research on this issue.
ENSO is the significant wave that makes heat flow on troposphere and low stratosphere over the tropics. As it is, this flow affects not only atmosphere but also the ocean below the air. When the water vapor flow is born by ENSO, it can result in flood or drought on the nation around. And if the water vapor is combined with low atmospheric pressure, it becomes hurricane and storm.
WHY WE SHOULD KNOW ABOUT ENSO?
In these days, there are more natural disasters than past century and they result in huge scale of damage on human life and properties.
Studies are needed for the prediction on when these disaster occurs, how large it will be, and why it occurs.
We choose the atmospheric wave, especially ENSO for the research on this issue.
ENSO is the significant wave that makes heat flow on troposphere and low stratosphere over the tropics. As it is, this flow affects not only atmosphere but also the ocean below the air. When the water vapor flow is born by ENSO, it can result in flood or drought on the nation around. And if the water vapor is combined with low atmospheric pressure, it becomes hurricane and storm.