Monsoon Current Affairs - 2019
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Reeling under drought the government of Karnataka is planning for cloud seeding project to influence the upcoming monsoon and capture as much water as possible from the rain clouds. The government of Karnataka has called the tenders for cloud seeding operations to enhance rainfall during the monsoons of 2019 and 2020. The cost is expected to be Rs 50 cr per year.
What is Cloud Seeding?
Cloud Seeding is a process of intervening chemically to induce precipitation rain or snow from clouds. Rain occurs when moisture in the air reaches levels at which it can no longer be held.
Cloud seeding aims to facilitate and accelerate the process by making available chemical ‘nuclei’ for condensation to take place. The agents used as nuclei are iodides of silver or potassium, dry ice (solid carbon dioxide), or liquid propane.
Earlier Efforts of Karnataka
Karnataka had undertaken a similar exercise through Project Varshadhare in 2017. The project was seen as a successful as the data suggested that rainfall was enhanced by 27.9% and there was an extra inflow of 2.5 tmcft into Linganamakki reservoir. This was a huge success because due to procedural delays and inconsistent monsoon season, the two planes could only fly for 37 days. The results were able to address the scepticism about cloud seeding.
Weather scientists have predicted normal monsoon in June-September 2018 monsoon season as prevailing conditions as well as neutral ENSO were favourable for good monsoon rainfall. India receives 89 cm of rainfall during four-month monsoon season, which is almost 75% of its annual rainfall. In 2017 monsoon season, country as whole had received rainfall that was 95% of its long-period average.
The most important favourable condition for good monsoon is near-neutral to neutral ENSO (El Nino Southern Oscillation) in equatorial Pacific Ocean, off coast of South America. Global climate models are showing near-neutral conditions prevailing in Pacific Ocean and it will remain this way through most of the year.
Moreover, La Niña conditions are present and equatorial sea surface temperatures (SSTs) are below average across central and eastern Pacific Ocean. The transition from La Niña to ENSO-neutral is most likely during March-May season, with neutral conditions likely to continue into second half of year. SST anomalies in eastern tropical pacific are ENSO-neutral during coming summer and hence normal monsoon is expected this year.
ENSO (El Nino Southern Oscillation)
ENSO refers to anomalies in SSTs in Pacific Ocean off coast of South America which has sometimes been observed to have near-decisive impact on monsoon rainfall. In El Nino, a warmer than usual SST is observed in Pacific Ocean off coast of South America . This condition is associated with suppressed monsoon rainfall in India. La Nina is opposite ENSO and is more favourable for monsoon. It is known to help monsoon rainfall in India. When anomalies (deviations from usual SST in the Pacific Ocean) are too small or absent, monsoon rainfall over India is normal.