India’s icy route to studying monsoons

In December 2015, an acoustic sensor on India's IndArc underwater observatory in the Arctic recorded unusual glacial ice melting during the winter polar night. Deployed by the Chennai-based National Institute of Ocean Technology (NIOT) at Kongsfjorden in Norway's Svalbard in 2014, the observatory enabled researchers to study global warming in the Arctic and its effects on the summer monsoon.The Indian govt planned to set up a similar observatory deep in the Arctic Ocean.
"We wanted to explore the open ocean down to 3,000m. We might deploy a moored buoy and collaborate with other countries, as we needed ships for ocean research," said M Ravichandran, Secretary of the Union Ministry of Earth Sciences. The observatory, which had more than 10 sensors (15m-192m depth), recorded a 0.15°C temperature rise in seawater below 50m during summer and thermal inversions. A recent NCPOR study found that shrinking Arctic ice caused heavier monsoons in central and northeast India and reduced rainfall in western and peninsular India due to altered atmospheric circulation.
"Ice melting was normally recorded in summer, so winter melting was unusual. Our autonomous passive acoustic monitoring system detected low-frequency sea ice melting during 2015 and 2019, linked to a cyclone that created warm atmospheric and ocean conditions," said G Latha, Head of NIOT's Ocean Acoustics Group.
The observatory measured seawater temperature, salinity, and currents at various depths. "In winter, sensors were the only data source, despite starting expeditions last year," said Balaji Ramakrishnan, NIOT Director. Though imported, there were indigenous components such as an automatic release mechanism that protected the main mooring from passing ships or icebergs. The observatory was otherwise held in place by a 550kg sinker weight with GPS to track drifts. "Retrieval and redeployment was a three-week process in summer," said M Arul Muthiah, Head of Ocean Observation Systems Group at NIOT. "Our next cruise will be in 2026."