Tropical cyclones ? Impact on Monsoon

Tropical cyclones – Impact on Monsoon

Background:
 We will discuss about Tropical cyclones here and how they impact Monsoon season. In addition, we will understand relationship between Global warming and Tropical cyclones.

What are Tropical cyclones??
 Tropical cyclones are powerful storms that form over warm ocean waters near the equator. They are characterized by strong winds, heavy rainfall, and a well-defined centre called the eye.

What are impact of Tropical cyclones on Monsoon?
 It accelerates the onset of Monsoon. For example, if a cyclone lies further north in the Bay of Bengal, the back winds blowing from the southwest to the northeast can pull the monsoon trough forward, and assist in the monsoon’s onset.
 It brings lot of moisture with it. South-westerly winds associated with tropical cyclones over the Arabiansea bring  good quantity of moisture into the Indian sub-continent which helps bring rainfall.
 However, there are some negative impacts as well such alteration of wind patterns. At times, cyclones in Bay of Bengal can cause winds to turn around, inhibiting the northward progression of the monsoon winds over the region.
 Untimely cyclonic activities also create uncertainty in the monsoon season making it difficult to predict exact onset of monsoon season.

What is the impact of Global Warming on Formation of cyclone?
 Increased warming activities along the Arabian and Bay of Bengal areas have resulted in increased frequency and intensity of cyclones. For example, Cyclone Amphan in 2020 caused serious destruction of infrastructure.
 Global warming influences the timing and duration of the monsoon season, leading to altered monsoon onset and withdrawal dates.
 Extreme weather events are due to the Global warming. For example, in the past 5 years we may have seen sufficient rains but the pattern has been different. Some regions have seen more rainfall while others have seen less. This impacts cropping patterns, brings floods in some regions etc.
 Global warming intensifies the impact of El-Nino on the Indian monsoon. This results in less rainfall and drought like situation in the country.

Some terms that you should know:

Atmospheric Bridge
 An atmospheric bridge is a connection between ocean basins via the atmospheric response to sea surface temperature (SST) anomalies in one region that influences ocean conditions over the rest of the globe.
 For example, the connection between the Arctic region and the Indian subcontinent through the atmosphere can influence the Indian monsoon by affecting wind patterns and moisture transport, potentially impacting the timing and intensity of the monsoon rains.

Oceanic Tunnel
 A mechanism that describes the transport of climate signals from the deep ocean to the surface ocean and across the equator via ocean currents, such as the Southern Ocean Intermediate Waters (SOIWs) that carry carbon isotopes from the Southern Ocean to the Tropical Atlantic.
 For example – The Gulf Stream. It acts as an oceanic tunnel, transporting warm water from the tropics to higher latitudes, affecting the climate and weather patterns in those regions.