Dhaka appeared almost 5C hotter in independently collected temperature data on April 25, compared with the data released by the Bangladesh Meteorological Department on the day, revealing the significant extent of deviation in the state-run weather agency鈥檚 meteorological observation.
While environmentalists and meteorologists acknowledged the BMD鈥檚 development in forecasting mechanism over the years, they said that it needed further improvement based on more reliable temperature and humidity data.聽聽
At 11:40am on April 25, the temperature at sector 13 in Uttara was recorded at 44C by the Center for Atmospheric Pollution Studies, a non-governmental organisation working on environmental pollution and meteorological condition.
But the BMD found Dhaka鈥檚 maximum temperature聽 on the day at 39.1C.
On the same day, the CAPS at 2:39pm found the temperature at the Muhammadpur Bus station at 43C, while at 12:48pm in Gulshan at 42C.
Dhaka鈥檚 temperature exceeded 41C at least thrice at different spots visited by the CAPS between April 16 and 25.
The BMD so far this year recorded the highest temperature of Dhaka on April 20 at 40.6C, which the official data revealed as the second hottest day since 1960.
The huge deviation in temperature reading shows that the BMD does not have enough weather stations to collect meteorological data, environmentalists and meteorologists said.
鈥楾he deviation bears huge public health consequences because underestimation could potentially fail to issue a forecast that could save many lives, particularly when global warming is making heatwaves lethal,鈥� said Ahmad Kamruzzaman Majumder, who teaches environmental science at Stamford University Bangladesh.
High temperature together with humidity can pose extreme risks for human health. The BMD does not have a heat index measuring what it really feels to human body in a certain temperature with certain humidity.
With 62 per cent humidity, the 44C temperature could mean extreme danger for humans with heat stroke becoming imminent, the CAPS warned, based on the heat index adopted by the USA鈥檚 National Weather Service.
On April 25, the CAPS found the humidity in Uttara at 25.1 per cent.
鈥楾emperature reading could vary in a distance of 10 yards depending on the method and place of data collection,鈥� M Shahidul Islam, who teaches geography and environment at Dhaka University, told 抖阴精品.
Reading temperature from high above ground over grassy land should give lower figures than reading temperature standing in concrete rooftop or on metaled road with busy traffic, he explained.
The BMD takes temperature reading at two metre height in a grass-covered ground on its Agargaon office premises covered with trees, secured with tall walls from public.
In the capital, a vast city covering nearly 300 square kilometres with around two crore people, the BMD has only one weather station in Agargaon.
Studies have revealed that Dhaka suffers from serious microclimatic condition, which refers to localised weather conditions. In cities like Dhaka the temperature at a particular place could be very high due to heat island effect, which occurs when infrastructure absorbs sunlight and re-radiate.
Adrienne Arsht-Rockefeller Foundation Resilience Center, a Washington-based non-governmental organisation, revealed in a study that temperatures on road surfaces in Dhaka, filled with people and vehicles burning the world鈥檚 most low-graded petrol, could reach up to 60C.
Temperatures are typically 12 degrees higher inside tin-roofed homes and workplaces, the report added.
Not only in Dhaka, the BMD鈥檚 stations elsewhere in the country are rather located in secluded leafy places with no public activities taking place there.
The BMD even does not have weather stations in every district. It has 61 weather stations across Bangladesh, including 18 weather stations in Chattogram division, 10 in Dhaka, eight in Rajshahi, seven each in Barishal and Khulna and two each in Rangpur, Mymensingh and Sylhet divisions.
Chapainawabganj, Natore, Joypurhat, Habiganj and Sunamganj districts have no weather stations.
Meteorologists at the BMD admitted that their weather stations are insufficient, particularly for observing how hot it gets because of temperature.
They, however, said that temperatures taken at their stations are highly reliable and taken in accredited instruments in line with the standard of the World Meteorological Organistaion.
Dhaka University鈥檚 meteorology department chairman Fatima Akter said that data taken at a weather station gives an idea of the area鈥檚 temperature but it might not be much useful in everyday life such as taking decision regarding public health issues.
鈥楢 more appropriate weather observation needs more data,鈥� said Fatima, adding that the BMD should increase its number of weather stations.
The real feeling of temperature should be measured, she said, adding that presence of humidity and wind direction could greatly influence the feeling of hot.
On Saturday, the BMD said that a very severe heatwave was sweeping through the district of Chuadanga and a severe heatwave gripped the districts of Rajshahi, Pabna, Sirajganj, Jashore and Kushtia.
A mild to moderate heat wave has been sweeping through Dhaka and Barishal divisions, the rest parts of Rajshahi and Khulna divisions and the districts of Dinajpur, Rangamati, Chandpur, Feni and Bandarban with chances of it continuing, the BMD said.
Bangladesh鈥檚 highest maximum temperature of 42.7C was recorded in Chuadanga. Dhaka recorded its maximum temperature at 37.4C.
The agency predicted the temperature to slightly rise today.
It has predicted drop in temperature from May 2 onward.
