Multi-decade data may help predict how violent storms will affect India

Scientists have mapped the soil moisture and temperature variations in India over five decades using satellite data, creating a resource that may be a critical for improving predictions of how violent storms will affect any area.

Thunderstorms embedded within Indian monsoon systems can deluge areas with dozens of inches of rain in little time, causing severe flooding and the loss of hundreds of lives each year.

Better predictions of when, where and how much rain will fall is key to saving property and lives, researchers said in a statement.

The team, including those from Indian Institute of Technology Bhubaneswar and National Institute of Technology Rourkela, in collaboration with the Ministry of Earth Sciences developed multi-decade soil moisture and soil temperature fields using variety of surface and satellite data.

They have shown that fine-scale data, never before available for India's monsoon regions, is a critical ingredient to understanding and improving predictions of how violent storms will behave over land.

Just as storms change behaviour based on the landscape -- such as moving from water to land -- or from encountering a cold or warm front, they also react to changes in wet or dry and warm versus colder soils.

"For a long time Indian monsoon research has focused as an oceanic feedback, but in recent years we have seen localized heavy rain embedded within thunderstorm events with flooding and cloud bursts that occur over land," said Dev Niyogi, a professor at Purdue University in the US.

"What we have learned is that gradients in soil moisture and soil temperature help create an atmospheric frontal boundary and can unleash violent reactions from a storm," said Niyogi, who led the study published in the journal Scientific Data.

"Understanding these locations climatologically is therefore quite important to help these predictions," he said.

Researchers worked more than three years to compile different datasets and assimilate global satellite soil moisture and soil temperature data from 1981-2017 and beyond.

Their product now provides gridded data every three hours for every 4 kilometre parcel of land giving soil moisture and temperature in India.

Combined with observed weather during that period, the data can improve models used to predict future storms.

"This data is useful for a host of applications, including to help make decisions about where to grow crops or places in which we can adapt to prevent flooding or erosion," Niyogi said.

Niyogi added that the data collection was possible because of the investment India has made through its Monsoon Mission and the partnership Purdue has created with the Indian government and scientists.

"Working together, between Purdue and the Indian teams, as well as the support we got on both sides, we could create a product that has been desired for a number of decades now," Niyogi said.