52.9°C at Mungeshpur in Delhi was incorrect by 3°C: Met dept blames faulty sensor
The agency deleted the station’s Saturday recording from its website and said the sensor is being replaced
The record high temperature of 52.9°C at the Mungeshpur weather station on Wednesday was incorrect by three degrees due to a faulty sensor that led to the higher reading, the India Meteorological Department (IMD) said on Saturday, adding that it will now review all automatic monitors acrossDelhi.
The agency deleted the station’s Saturday recording from its website and said the sensor is being replaced, following recommendations from a three-member panel formed to review the temperature, which would have broken Delhi’s all-time record.
“The data from Mungeshpur AWS (automatic weather station) should not be considered. We are in the process of replacing the sensor within a few days,” said IMD director general Mrutyunjaya Mohapatra.
“While updating our long-term records also we will consider that this station had given some erroneous readings. Further... it is a positive bias only. We will examine the AWSs and course corrections, if any will be carried out individually,” he added.
Similarly, Union minister of earth sciences Kiren Rijiju, in a post on X , said, “On 29th May, 2024, Mungeshpur’s AWS reported a temperature of 52.9°C, our India Meteorological Department team quickly investigated and found a 3°C sensor error.”
IMD further clarified that the exact reading of the day at the time when maximum temperature was recorded is unclear. However, the temperature recorded by AWS was higher by 3.1°C during the time of occurrence of maximum temperature, that is 3.15 pm, on May 30.
The weather agency’s move to rectify the error at Mungeshpur comes a day after IMD’s Nagpur office also said a reading of 56°C at an automatic station was incorrect.
The earth sciences ministry and IMD had set up a committee to examine the accuracy of the reading. The panel released its findings on Saturday, recommending that agency replace the sensor and commission a third-party audit
The panel also said there were no significant discrepancies in temperatures at 14 other automatic stations in Delhi on May 29.
“It’s important to calibrate the AWS instruments by comparing the readings with standard instruments. Regular calibration is needed or there can be positive or negative bias. Such errors are possible,” said Mahesh Palawat, vice president, climate change and meteorology at Skymet Weather.
IMD has five major stations, referred to as climate stations, which report the observations over long periods. The long period data fulfilling all the exposure conditions are available from five surface observatories of IMD, officials said.
“The expert team of IMD checked the authenticity of the temperature reported at Mungeshpur by comparing it with standard instruments on May 29 and 30 at the site. It was found that there was a positive bias in reported temperature,” an IMD official shared.
The bias varies during different times of the day, the maximum difference being observed at the time of occurrence of the daytime maximum, according to officials.
The data shared by IMD, as seen by HT, shows that the AWS value was higher by 3.1°C from the standard instrument value at 3.15 pm which is when the maximum is usually recorded.
The AWS values at 3 pm, 3.15pm and 3.30 pm on May 30 were 48.5°C, 48.5°C and 48°C, respectively. The standard instrument values at the same three times were 45.5°C (difference of 3°C), 45.4°C (difference of 3.1°C) and 45.3°C (difference of 2.7°C) respectively, officials said.
In accordance with the readings, IMD said, “The temperature sensor of AWS Mungeshpur is found to report about 3°C higher maximum temperature than the maximum temperature reported by the standard instrument. The comparison of maximum temperature reported by AWS stations at other locations with departmental manual surface observatories in Delhi showed no significant difference.”
The Ministry of Earth Sciences said that the AWS temperature sensors might be examined and calibrated at regular intervals by the Surface Instrument Division of Pune, in their recommendations after the findings were released.
“Site Acceptance Test should be carried out by comparing the temperature measured by AWS with standard instrument continuously for at least 24 hours at hourly intervals. If possible, a third-party audit should be done to authenticate the data quality of AWS. At the time of installation, the Factory Acceptance Test should be carried out in different temperatures,” the Ministry added in their recommendations.
It further stated that routine maintenance of the AWS installed across the country in a planned manner should be done and stringent automatic quality control should be applied to the observed data from AWS before uploading to the website for the general public.