An air quality monitoring station at National Central University (NCU) has become an index station for NASA’s regional measurements due to the accuracy of its data, the university said yesterday.
The station uses micropulse lidar to determine the source of air pollutants, by measuring changes in wave forms when they are bounced back by atmospheric particulate matter, the university said.
Chang Shuenn-chin (張順欽), director-general of the Environmental Protection Administration’s (EPA) Department of Environmental Monitoring and Information Management, said the station has overcome the challenge of determining pollutant sources, which had plagued EPA officials before.
Photo: CNA
“Although ground-level sensors can tell you about the special characteristics of pollutants in a particular area, they cannot tell you the direction particles fall in or how they disperse,” he said.
The EPA started using micropulse lidar technology from NASA in 2002, when it began long-term monitoring of particle dispersal.
The data it collected allowed it to analyze air pollution patterns and concentrations, and to gain a more accurate understanding of air quality changes, Chang said.
The micropulse lidar system can gather readings from as high as 30km in the atmosphere, at a vertical resolution of 75m, and gathers information 24 hours a day, he said.
“If the wave forms of backscattered electrons it detects are irregular, it has likely detected elements from the Earth’s crust, for example from a sandstorm,” he said.
“Globular wave forms likely indicate pollutants produced by high-temperature combustion,” he said.
NASA has collected atmospheric data in this manner since 2000 through the US federated Micro-Pulse Lidar Network (MPLNET), university assistant professor Wang Sheng-hsiang (王聖翔) said.
The network collects data from around the world, and is able to analyze the environmental effect of smog and sandstorms in China, as well as from the slash-and-burn agricultural practices employed in Indochina, he said.
MPLNET comprises 26 monitoring stations worldwide, four of which are in Taiwan. Taiwan’s stations are at the National Central University in Taoyuan, as well as in Taichung’s Situn District (西屯), Yunlin County’s Douliou City (斗六) and Kaohsiung’s Zuoying District (左營).
The university’s station was added to MPLNET due to the maintenance of its equipment and the reliability of its data, Wang said.
“The university’s system is in a temperature and humidity-controlled environment, and the lens is cleaned even more frequently than those at US monitoring stations,” he said.
Cooperation with NASA on MPLNET is important given the global interest in tackling air pollution and improving air quality, Chang said.
Air quality can be affected by natural or synthetic phenomena, he said.
Examples of the former include sandstorms, volcanic activity, sea spray, forest fires and the erosion of geological formations, while sources of synthetic pollutants include factories, motor vehicles, construction and farming, Chang said.
Air pollutants include particles with a diameter of up to 10 micrometers and those with a diameter of up to 2 micrometers, ozone, vulcanized materials, nitrogen oxide, carbon monoxide and lead.
The EPA measures air pollution nationwide at 111 monitoring stations, which include 77 standard monitoring stations, 10 mobile stations and other facilities that take measurements using light and other methods.
The stations have measured decreases in most pollutants in the past few years, but have shown annual increases in the concentration of ground-level ozone, which can cause breathing difficulties and chest pain, the EPA said.
Air quality in Taiwan is affected by seasonal winds and geography, Chang said.
“Strong northeasterly winds blow between October and April, bringing pollutants from China,” he said, adding that the central mountain chain then weakens the wind, so that pollutants become trapped above central and southern Taiwan.
However, southwesterly winds that blow between May and September bring stronger winds to central and southern Taiwan, so air quality in those regions improves, he said.
Meanwhile, air quality is worse during the day due to human activity, with pollutants reaching peak concentrations at about 6am and 6pm due to heavy traffic, he said.
Also, concentrations of nitrogen oxide and carbon monoxide are on average 1.2 times higher during work days than on weekends, he said, adding that concentrations are 1.7 times higher during rush hour.
Meanwhile, Chang said that the best time to jog outdoors is between 4am and 7am.
‘DENIAL DEFENSE’: The US would increase its military presence with uncrewed ships, and submarines, while boosting defense in the Indo-Pacific, a Pete Hegseth memo said The US is reorienting its military strategy to focus primarily on deterring a potential Chinese invasion of Taiwan, a memo signed by US Secretary of Defense Pete Hegseth showed. The memo also called on Taiwan to increase its defense spending. The document, known as the “Interim National Defense Strategic Guidance,” was distributed this month and detailed the national defense plans of US President Donald Trump’s administration, an article in the Washington Post said on Saturday. It outlines how the US can prepare for a potential war with China and defend itself from threats in the “near abroad,” including Greenland and the Panama
The High Prosecutors’ Office yesterday withdrew an appeal against the acquittal of a former bank manager 22 years after his death, marking Taiwan’s first instance of prosecutors rendering posthumous justice to a wrongfully convicted defendant. Chu Ching-en (諸慶恩) — formerly a manager at the Taipei branch of BNP Paribas — was in 1999 accused by Weng Mao-chung (翁茂鍾), then-president of Chia Her Industrial Co, of forging a request for a fixed deposit of US$10 million by I-Hwa Industrial Co, a subsidiary of Chia Her, which was used as collateral. Chu was ruled not guilty in the first trial, but was found guilty
A wild live dugong was found in Taiwan for the first time in 88 years, after it was accidentally caught by a fisher’s net on Tuesday in Yilan County’s Fenniaolin (粉鳥林). This is the first sighting of the species in Taiwan since 1937, having already been considered “extinct” in the country and considered as “vulnerable” by the International Union for Conservation of Nature. A fisher surnamed Chen (陳) went to Fenniaolin to collect the fish in his netting, but instead caught a 3m long, 500kg dugong. The fisher released the animal back into the wild, not realizing it was an endangered species at
DEADLOCK: As the commission is unable to forum a quorum to review license renewal applications, the channel operators are not at fault and can air past their license date The National Communications Commission (NCC) yesterday said that the Public Television Service (PTS) and 36 other television and radio broadcasters could continue airing, despite the commission’s inability to meet a quorum to review their license renewal applications. The licenses of PTS and the other channels are set to expire between this month and June. The National Communications Commission Organization Act (國家通訊傳播委員會組織法) stipulates that the commission must meet the mandated quorum of four to hold a valid meeting. The seven-member commission currently has only three commissioners. “We have informed the channel operators of the progress we have made in reviewing their license renewal applications, and