MADDEN JULIAN OSCILLATION - GEOGRAPHY
News: Cyclone may affect course of monsoon
What is in the news?
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Recently, Cyclone
Biparjoy in the Arabian Sea intensified into a very severe cyclone.
Key details of the Cyclone:
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It is expected to move
northwards and turn towards Oman in the coming days.
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While this will help the
monsoon onset in Kerala.
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An exceptionally warm
Arabian Sea, a weak monsoon onset, and favorable Madden Julian Oscillation
(MJO) conditions in the Indian Ocean are favoring this cyclone.
Madden Julian Oscillation Condition:
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The Madden-Julian
Oscillation (MJO) is the largest element of intraseasonal variability in
tropical weather.
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It is characterized as an
eastward movement of enhanced and
suppressed tropical convection over a 30- to 60-day period, on average.
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In
the enhanced phase, winds at the surface converge and air rises through the
atmosphere.
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This rising motion allows air to cool and condense, bringing more rainfall.
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In the suppressed phase,
winds converge higher up in the atmosphere, forcing air to sink and then
diverge at the surface.
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The sinking air warms and dries, consequently suppressing rainfall.
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After
a region of enhanced convection comes a region of suppressed convection.
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Monsoon
break in the August first week is caused by the Madden Julian Oscillation.
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The
MJO phases
○ Phase 1 –
Enhanced convection (rainfall) develops over the western Indian Ocean.
○ Phase 2 and 3 –
Enhanced convection (rainfall) moves slowly eastwards over Africa, the Indian Ocean and parts of the Indian subcontinent.
○ Phase 4 and 5
– Enhanced convection (rainfall) has reached the Maritime Continent (Indonesia and West Pacific)
○ Phase 6, 7 and 8
– Enhanced rainfall moves further eastward over the western Pacific, eventually dying out in the central Pacific.