Context :

Southwest monsoon 2022 will be “normal” predicted by private weather forecaster Skymet. El Nino and Indian Ocean Dipole (IOD) are not going to affect it.

What is Indian Ocean Dipole?

The term “Indian Ocean dipole” refers to a phenomenon when two poles of the same substance have opposite qualities. As a result, this geographical occurrence takes place in the Indian Ocean and is related to the sea surface temperatures on two of its sides, each of which has a different temperature profile.

The western Indian Ocean grows warmer (positive phase) and then gets colder (negative phase) than the eastern Indian Ocean during the periodic oscillation of sea surface temperatures known as the Indian Ocean Dipole (IOD), also known as the Indian Nino. The tropical region includes the Indian Ocean.

The ocean’s eastern side has a colder temperature if the western side is warmer. Conversely, if the ocean’s eastern side is warmer, the western side will be cooler. The Indian Ocean Dipole is the name given to this erratic movement in temperature. The Indian Ocean Dipole is the name given to this erratic movement in temperature. It is comparable to the Pacific Ocean’s El Nino and La Nina events.

Positive Indian Ocean Dipole

Because the westerly winds above the equator lessen during this period, warm water might flow to Africa. Changes in the winds also allow for a surge of cold water to move from the deep ocean to the east. This causes temperature disparities in the tropical Indian Ocean, with the east experiencing colder than usual water and the west enjoying warmer than usual water. It has been concluded that this occurrence will be advantageous to the monsoon. A positive dipole in the Indian Ocean is the result.

Negative Indian Ocean Dipole

During this phase, warmer water gathers towards Australia as the westerly winds along the equatorial line intensify. This causes temperature variations in the tropical Indian Ocean, with warmer-than-average water in the east and cooler-than-average water in the west. The monsoon’s progress through India is hampered by this phenomenon.

Indian Ocean Dipole Impacts on India

Strong IOD effects in 1997 and 1998 led to exceptionally heavy monsoons in the Indian Subcontinent. Due to a large positive IOD, this happened. A similar thing occurred in 2006. There have been about 12 positive IODs since 1980, however, only one big negative IOD since 1980 occurred in 2010. Positive IOD tests occurring repeatedly are unusual and extremely concerning because they contributed to the Black Saturday bushfires.

When a positive IOD with La Nina was built in 2007, it was a highly exceptional occurrence. Given that it had only occurred once before, in 1967, this was important (as per the historical records after discovery). Catastrophic flooding in Queensland in 2010–2011 and in Victoria in 2011 was caused by a severe negative IOD that built up and was exacerbated by a potent La Nina.

These trails of succeeding positive IODs are anticipated to occur at least twice every 1000 years, according to forecasting and modelling. The twentieth century also reveals a rise in the strength, frequency, and prevalence of positive IODs.

FAQs About Indian Ocean Dipole (IOD) and Its Impact on India’s Monsoon

Q. What is the Indian Ocean Dipole (IOD)?

Answer:- The Indian Ocean Dipole (IOD) is a climate phenomenon that occurs in the Indian Ocean, where two poles of the same substance experience opposite temperature qualities. It involves the periodic oscillation of sea surface temperatures, with the western side of the Indian Ocean becoming warmer during the positive phase and colder during the negative phase compared to the eastern side.

Q. How is the IOD similar to El Nino and La Nina in the Pacific Ocean?

Answer:- The IOD is comparable to El Nino and La Nina events in the Pacific Ocean. Like El Nino, a positive IOD can bring warm water to certain regions, affecting weather patterns. Conversely, a negative IOD can lead to cooler-than-average water temperatures, similar to La Nina’s effects.

Q. What are the impacts of a positive IOD on India’s monsoon?

Answer:- During a positive IOD phase, warm water flows towards Africa due to weakening westerly winds above the equator. This allows for a surge of cold water from the deep ocean to move eastward. As a result, the eastern side of the Indian Ocean experiences colder-than-usual water, while the western side becomes warmer. A positive IOD is believed to be advantageous for the Indian monsoon.

Q. How does a negative IOD affect India’s monsoon?

Answer:- During a negative IOD phase, warmer water accumulates towards Australia as westerly winds intensify along the equator. This leads to temperature variations in the tropical Indian Ocean, with warmer-than-average water in the east and cooler-than-average water in the west. The progress of the monsoon through India can be hampered by this phenomenon.

Q. Are there any historical instances of significant IOD impacts on India’s monsoon?

Answer:- Yes, there have been instances where strong IOD effects led to exceptionally heavy monsoons in the Indian Subcontinent. Notably, positive IODs in 1997, 1998, and 2006 contributed to heavy monsoons. Additionally, a severe negative IOD in 2010, combined with a potent La Nina, caused catastrophic flooding in Queensland and Victoria, Australia.

Q. How frequent are positive and negative IOD occurrences?

Answer:- Forecasting and modeling suggest that positive IODs are expected to occur at least twice every 1000 years. The twentieth century has also shown an increase in the strength, frequency, and prevalence of positive IOD events.

Q. How does the Indian Ocean Dipole impact Australia and other regions?

Answer:- The IOD’s positive and negative phases can have significant effects on Australia’s weather patterns, influencing droughts, flooding, and bushfires. Additionally, the IOD can influence weather conditions in other regions surrounding the Indian Ocean.

Q. How do scientists monitor and forecast the Indian Ocean Dipole?

Answer:- Scientists monitor sea surface temperature anomalies and wind patterns in the Indian Ocean to track the IOD’s phases. Forecasting models and historical data are used to predict potential impacts on weather and climate patterns in affected regions.

Read also:- What is El Niño