“This is the first article related to the monsoon season of 2013 and it will be followed by many more articles”
‘Introduction to the Monsoon season’
Another monsoon season is coming to Pakistan this year as always, the giant winds are slowly taking shape to once again cover India and then move straight towards Pakistan. The word “monsoon” is derived from Arabic, Hindi and Urdu words of mawsim (موسم) meaning weather, there is also some indications the word is derived from Dutch word of monsun. The Englishmen used to use this word to define a seasonal prevailing wind in the region blowing from the south-west between May and September and bringing heavy rainfalls to British India.
How do Monsoon form?
Before the monsoon season, the land and oceans start to heat up with the consequence that the air over the land warms faster and reaches a higher temperature than the air over the ocean. The hot air over the land tends to rise, creating an area of low pressure. This creates a steady wind blowing toward the land, bringing the moist near-surface air over the oceans with it, thus monsoon season begins.
A monsoon is traditionally defined as a seasonal reversal of wind direction which is accompanied by changes in precipitation. In Asia, the monsoon season runs from May to September, when Southern Hemisphere winds shift direction and blow north and west across the Equator into Asia, bringing moisture from the oceans they pass over on the way.
Threat from Negative Indian Ocean Dipole
The El-Nino Southern Oscillation (ENSO) have impact on the monsoon, it could be a negative or positive effect. In 2010, La Nina was one of the positive factors to have caused good monsoon across the Indian Subcontinent . La-Nina (late 2011 -2012) re-emerged late in November after one of the strongest La-Nina (2010- early 2011) in the weather history. Following are the conditions which could affect monsoon 2013;
- Neutral ENSO
- -IOD (Feared by the Japanese)
Before the strong La-Nina pattern, El-Nino (2009 – 2010) was dominating the world that transitional period between El-Nino and La-Nina was on the fastest in recent years in 2010. It was actually because of La-Nina that India and Pakistan saw a good monsoon in 2010 and 2011. In 2012 monsoon season, El-Nino conditions were developing but it was saved at the last moment by the Positive Indian Ocean Dipole. There is a strong possibility of -IOD developing in the month of July as the present conditions are favoring the negative development according to the Japanese Meteorologists.
El-Nino/La-Nina – South Oscillation
Both these phenomena are famous for having irregularity, it is thought that they happen every 5 year respectively but this study is not supported by other scientist. Overall there are two types of this phenomena;
- El-Nino is a spanish word which means boy, it may also refer to a Christ child, because of the periodic warming in the Pacific near South America that happens around Christmas. It 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. It forms due to the warming of Pacific Ocean thus the number of typhoons are increased in Pacific ocean while Atlantic ocean usually becomes calm due to intense wind shear. El-Nino is also said to increase malaria disease in India.
- 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. It happens due to the cooling of Pacific ocean.
The transformation of El-Nino in 2009 into La-Nina in 2010 was the quickest in recent years. It is also worth mentioning that both of them were strongest in their respective years and such quick change is very rare.
What is Indian Ocean Dipole (IOD)?
Like ENSO, there are two types of Indian Ocean Dipoloe. 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 in Australia and Indonesia.
Monsoon Special articles for 2013
You can read special monsoon article by Pakistan Weather Portal (PWP), here;
- Another Monsoon brewing for the same Sub-continent! – Part I
- Do we really need a monsoon season? – Part II
- Pakistan bakes in Oven: Bricks for Monsoon 2013 placed! – Part III
- Look back at Past: Pre-Monsoon rains are just around the corner? – Part IV
- Monsoon facing the biggest challenge from its own Ocean! – Part V
- Road map for ‘Monsoonistan’ laid: Rains move into Pakistan! – Part VI
TO BE CONTINUED…….