T. Lalith Singh

NGRI studies past temperatures in city to work out weather patterns

Changes in surface air temperatures diffuse in earth and perturb temperature distributions

These perturbations at subsurface are analysed to understand extent of warming or cooling

HYDERABAD: To generate data for a better understanding of global climate change and also work out climate patterns in the city during last few centuries, National Geophysical Research Institute (NGRI) has come up with a unique facility at its Choutuppal campus.

Set up at a cost of around Rs. 36 lakh and with the support of Department of Science and Technology, the Geothermal Climate Change Observatory has an automatic weather station located next to a set of boreholes which are dug up to 210 metres. At two-minute intervals, the station samples the surface air temperature, humidity, precipitation, solar radiation, wind speed and its direction and the same gets stored every 15 minutes.

According to Sukanta Roy, Project Head, Heat Flow Studies, the long-term changes in surface air temperatures due to climate change diffuse further down in the earth and perturb the natural temperature distributions. “These perturbations at subsurface can be analysed to understand how much warming or cooling has happened,” he says.

Since the temperature data for nearly last 100 years is available, the initiative is to tap the subsurface and arrive at temperatures that prevailed earlier to that. “There is no reliable record of temperature in the country for the period say from mid-1700 up to 1900 and this effort will equip us with the same,” he says. Thus, measuring the temperature in the boreholes that have been dug up at Choutuppal, NGRI scientists look at deducing the warming or cooling that took place during the last 300 years.

Tracking changes

An important assumption has been that the subsurface temperature changes track the surface temperature changes and using it, the present initiative looks at continuous recording of surface and subsurface temperature changes at the same site. “This allows us to study the nature and extent of tracking between the surface and subsurface temperature changes,” he points out.

In the last six months, certain inferences on the surface temperature history in last 150 years have been arrived with the work at the observatory and more correlations are being put in place. And it might be another two to three years before, the NGRI will be able to provide inputs on the kind of temperatures that prevailed in the city some three to four centuries back.