Ranchi: It's weather station versus observatory, as Kanke touching freezing point on January 10 and 11 heats up debate.

Indian Meteorological Department (IMD), which has an automatic weather station (AWS) on Birsa Agricultural University (BAU) campus, reported a minimum temperature on January 10 and 11 as 2.5°C and 5.9°C at Kanke. BAU's own surface observatory, over 100 metres away from the IMD station, clocked 0°C on both days.

A comparative study of temperature clocked by IMD's AWS and BAU's surface observatory this past one month shows their data seldom matched on any given date. On Monday, IMD and BAU minimum readings were 3.4°C and 1.1°C.

On the obvious question of who was wrong, both IMD Ranchi director B.K. Mandal and BAU professor of agro-meteorology and environment science A. Wadood claimed to be right.

IMD maintained that the sensor of its thermometer was accurate up to a variation of "plus-minus 0.2°C".

BAU claimed its surface observatory was a part of IMD and its instruments were from the IMD and certified by it. "IMD officials inspect them every two-three years. Officials from the local Met centre came here on our request and inspected them a few weeks ago," Wadood said. "We check instruments regularly as we issue farmer bulletins."

Declining to comment on the discrepancy, Wadood said they were satisfied with the BAU reading. "Our thermometer is kept 6 feet from the ground. Our observatory is on a low-lying land with irrigated fields and a pond nearby. The IMD weather station is on a comparatively higher level," Wadood said.

Mandal also refused to comment on the BAU reading but said they kept their sensor four feet above ground at a favourable spot.

"I can only say ideal conditions are a must for instruments to record with accuracy," he said. His colleague, who did not want to be named, said it was possible that wet fields and a pond near the BAU observatory dragged down its minimum readings.