The Inter Tropical Convergence Zone (ITCZ) is a belt of low pressure that circles the Earth at the equator. It is created by the meeting of the northern and southern trade winds. In contrast, the westerly jet stream, which blows from west to east in the middle latitudes, impacts weather patterns significantly.
The Southern Oscillation (SO) is a notable phenomenon involving wind and sea surface temperature shifts between the tropical eastern Pacific Ocean and the Indian Ocean. La Nina, characterized by cooler than average ocean temperatures, and El Nino, marked by warmer than average ocean temperatures, are part of this occurrence.
Monsoons and their Significance
Monsoons are seasonal winds that change their direction with the season. Their presence influences the South-West Monsoon, a crucial weather system for India. During the summer, due to differential heating and cooling, low pressure is created over the landmass of India, while comparatively high pressure occurs around the seas.
Along with other factors like the heated Tibetan plateau causing vertical air currents and low pressure, these elements together affect the Indian Monsoon’s intensity and position.
Influence of Indo-Pacific Circulations on Monsoons
The onset of the monsoon over the Kerala coast symbolizes the start of the four-month southwest monsoon season, accounting for over 70% of India’s annual rainfall. The India Meteorological Department (IMD) determines the monsoon onset based on significant transitions in atmospheric and ocean circulations in the Indo-Pacific region.
Rainfall consistency, intensity, and wind speed are specific parameters used to declare the onset. For example, if at least 60% of 14 designated meteorological stations in Kerala and Lakshadweep record at least 2.5 mm of rain for two consecutive days after May 10, the onset is declared on the second day.
The Impact of Delayed Monsoon on Agriculture and Water Resources
Delayed monsoon onset can significantly impact the agricultural sector, especially crop sowing timeframes. Farmers depend heavily on monsoon rains for irrigation, and a delay can affect crop yields and productivity. Furthermore, a postponed monsoon can cause water scarcity and impact hydropower generation due to insufficient water availability.
In the environment, delayed monsoon onset can affect vegetation growth, disrupt ecological cycles, and contribute to problems like soil erosion, land degradation, and reduced biodiversity.
The Influence of Indian Ocean Dipole (IOD) on Indian Monsoon
The IOD refers to the difference in temperature between the eastern (Bay of Bengal) and the western Indian Ocean (Arabian Sea). A positive IOD tends to bring more rainfall to India, while a negative IOD has a contrary effect.
However, the behavior of the Indian Monsoon has been changing due to human activities altering the landscape, leading to serious discussions about climate change and its impact on weather patterns. With increasing urbanization and deforestation, the natural balance is disturbed, leading to unpredictable changes in the monsoon’s behavior.
For instance, the UPSC Civil Services Examination asks candidates to discuss how much they agree that human alterations to the landscape have changed the Indian Monsoon’s behavior. Such discourse emphasizes our need to understand and adapt to these changes for a sustainable future.
Thus, thorough knowledge of atmospheric phenomena such as the Inter Tropical Convergence Zone (ITCZ), Westerly Jet Stream, and Southern Oscillation (SO) becomes essential in predicting and planning for changing weather patterns, especially in regions heavily dependent on monsoons, like India.
