Monsoon threatened by Indian Ocean Dipole!

This is the second monsoon article and it is a sequel of “Sub-continent awaits monsoon”

El-Nino and La-Nina in the month of June till September

The Pacific Ocean’s temperatures matters for the Monsoon

 Cooling and warming of Western Pacific Ocean does effect the Indian Monsoon while the weather of many other countries as well. There are too phases of this phenomenon;

  • El-Nino or El Nino-Southern Oscillation (ENSO) is a spanish word which means boy. ENSO causes extreme weather (such as floods and droughts) in many regions of the world. It causes drought in India, Pakistan, Bangladesh and many countries of the world, while it causes wet conditions and floods in other part of the world. It has a deep effect on the Indian monsoon.
  • La-Nina is a spanish word which means girl. La-Nina is the complete opposite of El-Nino. It causes wet conditions and floods in the Sub-continent while drought and dry weather over other parts of the world,
A positive Indian Ocean Dipole

Indian Ocean Dipole and monsoon

IOD is an irregular phenomenon in which the western equatorial of the Indian Ocean becomes warmer while the eastern equatorial cooler.It affects the Sub continent, Australia, Indonesia and many other surrounding countries. There are two phases of Indian Ocean Dipole; 1. Positive IOD 2. Negative IOD

  • Positive Indian Ocean Dipole (IOD) causes sea temperatures to rise in the western Indian Ocean with heavy precipitation in Sub-continent while it makes the sea temperatures cooler in the eastern Indian Ocean with drought or very little to no precipitation in Australia and Indonesia.
  • Negative Indian Ocean Dipole (IOD) causes cooler sea temperatures in western Indian Ocean with no rainfall in the Sub-continent while eastern Indian Ocean becomes warmer with heavy precipitation.

Past Monsoon season and Sub-continent

Monsoon brings much awaited rainfall to the Sub-Continent. It is vital for India’s economic growth while also for Pakistan. Different factors have their influence on the monsoon. Let us take a look of some past monsoon in the Indian-continent;

Pakistan drought – IOD and El Nino

Pakistan drought in 2000

In 1997, a positive IOD developed during the monsoon which usually means heavy rainfall for Indian Sub-continent but if you recall that year, Pakistan and North-Western India were going through a drought period. Karachi only had 19.4 mm rainfall during that monsoon compared to its average 145.6 mm rainfall. So why did drought occur in Pakistan with the presence of positive IOD? the answer is El-Nino. El-Nino pushed a high pressure over most of India including Pakistan that stopped the passage of monsoon rains.

Karachi flooded during 2009

Karachi flooded – But El Nino shokes India and Northern Pakistan

In 2009, IOD was in a neutral state meaning normal sea temperatures in the western and eastern half of the Indian Ocean but the El-Nino phenomenon caused 30% below normal monsoon rainfall in Pakistan and India that caused anxiety among the farmers of both the state especially India who depends 80% on these monsoon rainfall for their crops. But southern Pakistan that is Karachi and Hyderabad received above to very above normal monsoon rains than any other city of Pakistan during the monsoon of 2009. No one knows the reason, it might have been an isolated event.

Pakistan drowns – La Nina takes over

In 2010, La-Nina started gaining momentum in mid June and reached its peak in August. It caused heavy to extremely heavy rainfall all over Pakistan causing the great floods in Pakistan while isolated floods in India’s Kashmir. Karachi got 700 mm rainfall compared to its average of 145.7 mm rainfall during the monsoon.

And in 2011?

Normal monsoon has been forecasted by the Indian Meteorological Department (IMD) this year but since La-Nina is likely to die down this June or mid-July and a weak negative IOD is likely to form during the monsoon. So Sub-continent might get slightly below monsoon rainfall in some areas while slighty above in other. So lets wait for the monsoon!

 You can also read

you can read previous special monsoon article by Pakistan Weather Portal (PWP), here;
To be continued....

5 replies to “Monsoon threatened by Indian Ocean Dipole!

  1. Karachi did not get 700mm even it did not get 300mm in 2010. Why are you saying this? Punjab,nwfp and kashmir which got very above rainfall in 2010 but you are not saying about this

  2. Good article and information..shall I reproduce it on Vagaries ? Someone was asking about IOD on my blog.

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