What is ENSO, El nino, La nina, Southern Oscillation, Walker Circulation | UPSC / IAS
Summary
TLDRThis video script explains the El Niño-Southern Oscillation (ENSO) phenomenon, focusing on its occurrence in the Pacific Ocean. It describes the oscillation of ocean temperatures between warm and cool states, affecting global weather patterns. The script outlines three phases: the neutral phase with typical Walker circulation, El Niño with weakened trade winds causing a warm current shift, and La Niña with strong trade winds pushing warm currents westward, leading to contrasting weather effects in different regions.
Takeaways
- 🌊 El Niño and La Niña are part of the ENSO (El Niño-Southern Oscillation) phenomenon, which mainly occurs in the southern hemisphere, particularly in the Pacific Ocean.
- 🌡 The term 'oscillation' refers to the back-and-forth fluctuation of ocean temperatures, from warm to cool and vice versa.
- 🌍 The Pacific Ocean, being the largest ocean, is the key area where these temperature fluctuations occur due to its location at the equator and the intense sun rays it receives.
- 🔄 The 'neutral phase' of ENSO is a conceptual state for understanding, where the Central Pacific Ocean is warm, and trade winds push warm water towards the western Pacific.
- 🌀 Trade winds, also known as tropical easterlies, play a crucial role in the distribution of warm water in the Pacific Ocean.
- 🌧️ The western Pacific, known as the 'western Pacific pool,' becomes warm due to trade winds, affecting the atmosphere with increased temperature and moisture, leading to cloud formation and rainfall.
- 🌀 The Walker circulation is the pattern of rising air in the West and falling in the East, which is a key part of the neutral phase of ENSO.
- 🌊 El Niño occurs when trade winds weaken, allowing the warm pool to move towards the central and eastern Pacific, disrupting the Walker circulation and causing drought in Australia and heavy rain in South America.
- 🌧️ La Niña is the opposite of El Niño, with strong trade winds pushing the warm ocean current westward, leading to heavy rains in Australia and a cooling effect in the eastern Pacific.
- 🌡 Thermocline is the term used for the rising path of water temperature from the deep ocean to the surface, which is a significant feature during La Niña.
- 🔄 The oscillation between El Niño and La Niña is a continuous process, with each phase impacting weather patterns across the globe.
Q & A
What does ENSO stand for?
-ENSO stands for El Niño-Southern Oscillation, which refers to the periodic warming and cooling of the Pacific Ocean's surface temperature.
Why is the term 'oscillation' used in the context of ENSO?
-The term 'oscillation' is used because it describes the back and forth movement of the ocean temperature from warm to cool and vice versa.
Which ocean is primarily affected by ENSO?
-The Pacific Ocean is the primary ocean affected by ENSO, being the largest and located at the equatorial region.
What is the role of trade winds in the ENSO cycle?
-Trade winds, also known as tropical easterlies, play a crucial role in the ENSO cycle by pushing the warm ocean current towards the western Pacific during the neutral phase.
What is the 'neutral phase' of ENSO?
-The neutral phase is a conceptual state where no significant El Niño or La Niña conditions are present, and the Central Pacific Ocean is warm, serving as a baseline to understand the onset of ENSO phenomena.
How does the Walker circulation affect the weather patterns during the neutral phase of ENSO?
-During the neutral phase, the Walker circulation causes rising air in the western Pacific, leading to cloud formation and rainfall, while sinking dry air in the eastern Pacific results in clear skies and less rainfall near the South American coast.
What happens during the El Niño phase of ENSO?
-During El Niño, the trade winds weaken, allowing the warm ocean current to move towards the central and eastern Pacific, leading to a shift in weather patterns with heavy rainfall near the Peruvian coast and drought in Australia.
What is the significance of the thermocline during the La Niña phase?
-In the La Niña phase, the strong trade winds push the warm surface water towards the western Pacific, causing the cold water from the deep ocean (thermocline) to rise to the surface, affecting the temperature and weather patterns.
How does La Niña impact the weather differently from El Niño?
-La Niña, characterized by a cold ocean current, brings heavy rains to the western Pacific regions like Australia, Indonesia, and New Zealand, contrasting with El Niño's impact on the eastern Pacific.
What is the relationship between El Niño and La Niña in terms of their geographical locations?
-El Niño and La Niña are opposite phases of ENSO, with El Niño affecting the eastern Pacific and La Niña affecting the western Pacific, oscillating back and forth between these regions.
Why is the Pacific Ocean particularly susceptible to ENSO phenomena?
-The Pacific Ocean is susceptible to ENSO phenomena due to its size, location at the equator, and the presence of trade winds, which facilitate the movement of warm and cold currents.
Outlines
🌊 Understanding ENSO: El Nino and Southern Oscillation
This paragraph introduces the El Nino-Southern Oscillation (ENSO) phenomenon, explaining that 'El Nino' refers to the warm phase of the Pacific Ocean's surface temperature oscillations, predominantly occurring in the southern hemisphere. The term 'oscillation' indicates a back-and-forth movement, in this case, of the ocean's temperature between warm and cool phases. The focus is on the Pacific Ocean, the largest and most affected by these temperature changes due to its location at the equator and the intense sun exposure it receives. The paragraph sets the stage for a deeper exploration of ENSO by breaking it down into three phases: neutral, El Nino, and La Nina, starting with the neutral phase where the Central Pacific Ocean is warm, influenced by trade winds that push warm water towards the western Pacific, creating a cycle known as Walker circulation.
🌍 El Nino Phase: Warm Currents and Global Impacts
The second paragraph delves into the El Nino phase of ENSO, characterized by a weakening of the trade winds, allowing the warm pool of water in the western Pacific to shift towards the central and eastern Pacific. This movement signifies the oscillation referred to in the phenomenon's name. The displacement of the cold water by the warm current results in the upwelling of deep, cold water, altering weather patterns globally. The El Nino phase disrupts the Walker circulation, leading to droughts in Australia and heavy rainfall and flooding on the American continent, particularly around the Peruvian coast. The paragraph emphasizes the significant climatic effects of El Nino, urging viewers to associate the term with these weather changes.
🌧️ La Nina Phase: The Cold Counterpart to El Nino
The final paragraph discusses the La Nina phase, which is the cold phase of ENSO. Similar to the neutral phase, La Nina is marked by strong trade winds that push the warm surface current westward, allowing cold water from the deep ocean to rise to the surface, a process known as upwelling. This phase is characterized by a thermocline, the boundary between the warm surface water and the colder water below. The effect of La Nina is pronounced in the western Pacific regions, such as Australia, Indonesia, and New Zealand, where it brings heavy rains, contrasting with the droughts experienced during El Nino. The paragraph concludes by reinforcing the oscillating nature of ENSO, with El Nino and La Nina representing the warm and cold phases, respectively, that alternate across the Pacific Ocean.
Mindmap
Keywords
💡El Nino
💡Southern Oscillation
💡Pacific Ocean
💡Trade Winds
💡Walker Circulation
💡Thermocline
💡La Nina
💡Convection
💡Troposphere
💡Neutral Phase
💡Oscillation
Highlights
El Nino and Southern Oscillation (ENSO) is a climate phenomenon primarily occurring in the Southern Hemisphere.
The term 'oscillation' implies a back and forth movement, in this case, of ocean temperatures.
ENSO involves the oscillation of ocean temperatures between warm and cool in the Pacific Ocean.
The Pacific Ocean, being the largest and located at the equator, plays a central role in ENSO.
The neutral phase of ENSO is a theoretical baseline for understanding the cycle.
Trade winds, blowing from east to west, push warm water towards the western Pacific.
The western Pacific, known as the pool, is warmed by the trade winds and solar radiation.
Warm ocean currents affect the atmosphere, leading to convection and cloud formation.
Walker circulation is the pattern of rising air in the West and falling in the East.
El Nino phase is characterized by weak trade winds allowing the warm pool to move eastward.
During El Nino, the eastern Pacific experiences heavy rain and flooding due to the warm current.
La Nina is the opposite phase of El Nino, with strong trade winds pushing warm water westward.
La Nina results in a cold ocean current, affecting regions like Australia, Indonesia, and New Zealand with heavy rains.
Thermocline is the term for the rising path of water temperature from the deep ocean to the surface.
ENSO's oscillation is a continuous process with El Nino and La Nina phases alternating.
ENSO has significant global impacts on weather patterns and climate conditions.
Understanding ENSO is crucial for predicting climate changes and their effects on ecosystems and agriculture.
Transcripts
in this video we are going to learn
about Enzo II and ESCO if you break it
Ian stands for El Nino and s o stands
for Southern Oscillation because Enzo
phenomena mostly occurs at this southern
hemisphere just right below the equator
and when you look at the term
oscillation it gives us a hint that
something oscillates from one place to
another or back and forth if you want
you can pause the video and think about
what could be that thing well it's the
temperature that we are talking about
and not just any temperature ocean
temperature it is the ocean temperature
that oscillates back and forth from warm
temperature to cool temperature and
vice-versa now the next question that
should be in your mind is which ocean
are we talking about I'll give you a
hint it's the largest one Pacific Ocean
you see Pacific Ocean is this large pool
of water that exists on the western side
of the American continent and eastern
side of the Asian and Australian
continent this large pool of water gets
intensely warm due to the fact that it
exists right at the equator and we all
know that the equatorial region received
great amount of sun rays all throughout
the year so far we have learned what and
where ENSO takes place now it's time to
know how it all happens to understand
how ENSO occurs we will need to break it
into three phases that's how it will
make sense and step by step the concept
will get clearer the first phase is
neutral phase actually there is no such
thing as a neutral phase when it comes
to any of nature's phenomena you see
nature has a constant ongoing cycle that
has never stopped but for our own
understanding we will have to create a
neutral state where we can see how a
particular thing starts and goes on so
the first phase among the three phases
is the neutral phase in this phase this
Central Pacific Ocean is warm now let's
bring in the trade winds
trade winds are these wind that blows in
the tropical region from eastern side to
the western side they are also known as
tropical
easterlies so as we know that the
equator receives great amount of sun
rays and that's what warms the Pacific
Ocean the trade winds pushes the warm
ocean car
towards the Asian side because trade
winds blow from east to west and that
makes the western Pacific Ocean warm you
know the region around New Zealand
Australia and Indonesia this region is
called the western Pacific pool here the
ocean temperature is warm the warm ocean
current affects the surrounding
atmosphere by increasing the temperature
as well as the moisture content and we
know that warm air rises high into the
atmosphere it is through the convection
process and that's how clouds are formed
and then it rains the warm air then
travels east towards eastern Pacific
Ocean
you know the region near South America
especially countries like Ecuador and
Peru the warmer air when it goes up it
reaches the end of troposphere and if
you know the top of the troposphere is
cold when warm air meets cool air slowly
it loses its moisture content and the
air becomes dry the dry air travels
towards the eastern Pacific side and
comes down over the Peruvian coastal
region making the region cold this
pattern of rising air in the West and
falling in the East continues and it is
known as Walker circulation so this was
the neutral phase I hope you understood
this cycle it's plain and simple now
comes the second phase it's called El
Nino so in the neutral phase we saw that
the trade winds played an important role
in pushing the warm ocean current
towards the western Pacific now in this
phase the trade winds a weak yes there
are few months in a year when the trade
winds a week when the trade winds are
weak the warm ocean current do not get
any kind of push so what happens is the
warm pool of ocean water at the western
Pacific slowly moves towards the central
and eastern side of the Pacific Ocean so
this is where the oscillation term comes
in you see the warm ocean current is
replacing the cold ocean current that
exists in the central and eastern
Pacific
when I say replace what I mean is that
the cold water is dense and it settles
down in deep ocean and warm water goes
up and takes over the surface of the
ocean ok I hope you're understanding
when this warm ocean current moves
everything that is associated with it
like the convection process then the
formation of rain cloud everything moves
along with this warm ocean current what
you will notice now is that the Walker
circulation that we saw in the neutral
phase that one big looping pattern it's
now breaking into two parts just look at
this loop as a result the ocean
temperature near Australia is cool and
there is no rain though the inland parts
of Australia witness a severe drought
condition but on the other hand near the
Peruvian coast the warm pool of ocean
current brings heavy rain flood to the
American continent so whenever you hear
the word El Nino immediately think of
warm ocean current and the third phase
is La Nina this is similar to the
neutral phase in this phase the trade
winds are strong since trade winds blow
from east to west
hence it pushes the warm ocean current
from the eastern Pacific toward stay
west in Pacific now imagine this cold
water is dense and it settles down in
deep ocean so that means the temperature
of the ocean surface is warm now if the
trade wind pushes the warm surface ocean
current towards the western Pacific the
cold water from the deep ocean
immediately comes up at the surface
there's a word given to it it's called
thermocline thermocline is the rising
path of water temperature and the rest
of the process is same we saw that in
the neutral phase western Pacific region
of Australia Indonesia New Zealand gets
heavy rains strong the effect of La Nina
is more on these countries than El Nino
so El Nino is a warm ocean current and
La Nina is a cold ocean current remember
that if El Nino is at the eastern
Pacific then La Nina will be at the
opposite region that is western Pacific
and it oscillates back and forth
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