Research
Meteorology
The monthly mean temperature in Lulin Atmospheric Background Station (LABS) is around 5 to 14 °C. Lowest monthly cumulative rainfall appear in January, around 183 mm. In May and June, the plum rain bring rain fall to Taiwan. In summer, the Afternoon thunderstorms and typhoon bring maximum monthly cumulative rainfall, the highest value could up to 1300 mm per month.
he backward trajectories analysis at Mt. Lulin show the air mass usually passing through South-East Asia and reach to Taiwan alpine area (such list LABS) with westerlies during March to April. Westerlines bring biomass burning pullants decrease Taiwan/LABS air quality significantly. But in recent years (2015-2017), the trajectories show more north-east monsoon bring air mass from china to LABS in early spring, and that might cause more China pollutants reach to LABS.
After plum rain season start (Mid-April), the air mass come from South China Sea and Western Pacific Ocean, bring the clean ocean surface air with good air quality until September. In Fall, the air mass come form north as showed with the backward trajectories chart. In this season , there're more frequency that the frontal system to effect Taiwan weather. In Winter, there are more dry air from china pass through Taiwan directly, and carry the polluted air mass.
Air Pollution Measurement
Those pollution sources where locate in the upwind of Taiwan, are such like China, Indo-China or Southern Asia. The long-range transport pollution transported by the monsoon to Taiwan. For Mt. Lulin, the altitude is around 3000 meter above sea level; during February to April of each year, the biomass pollution transport to Mt. Lulin with westerlies from Indochina in spring time. By the way, clean sea surface fresh air mass transport to Mt. Lulin from South China Sea and western Pacific ocean in summer time.
During the biomass burning seasons , the average concentrations of CO, O3, PM10 and PM2.5 durning March to April are 234.4 ppb、54.3 ppb、20.5 µg m-3 and 17.0 µg m-3, respectively; which are 2.6, 2.3, 3.2 and 3.2 times more than its background value (the mean value in July), respectively.
Greenhouse Gases
By coding to 2007 IPCC Fourth Assessment Report (AR4), content about "Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level",especially for those greenhouse gase were increasing significantly as CO2, CH4, N2O and CFCS. The total radiation force of these greenhouse gases sum is about +2.63 Wm-2, that is a specific warming signal. Then, IPCC AR5 report show the global temperature already increase 1 °C since 1990, and sea level up 0.25 m.
Global warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide.
Taiwan EPA join with NOAA(CCGG) Global Greenhouse Gas Reference Network and NASA Aerosol Robotic Network(AERO). Measuring Greenhouse Gases in long-term, the data show CO2 concentration glowing rate is 2.7 ppm per year, other greenhouse gases such like CH4 and N2O concentration glowing rate are 7.7 and 0.9 ppb per year.
AcidRain
The monthly mean pH value of collected rainfall at LABS only reached below the standard of pH 5.0 in March, reaching the standard of acid rain affected by anthropogenic pollution, and the concentration of acid ion also increased significantly in March and April. This reason is obviously impacted by wester-lines transport the biomass burning pollutants from Indochina.
Air pollution has a widespread effect on plants, animals and entire ecosystems. Ozone pollution stifles tree and crop growth and causes leavesof common tree species to blacken and wither. Nitrogen and sulfur pollution that comes through rain, snow or fog can cause changes to soil and water chemistry which affects plants’ and animals’ ability to survive in an area. (Polluted Parks, How America is Failing to Protect Our National Parks, People and Planet from Air Pollution, NPCA ©May 2019)
Radiation
Aerosol optical depth is a measure of the extinction of the solar beam by dust and haze. The monthly mean chart of AOD at LABS shows that AOD value reaches the maximum in spring. Due to the fact of the altitude of the LABS in Mt. Lulin is higher than the atmospheric boundary layer significantly. And that’s why there would be less changes to effect by local urban pollutants, especially during mid-night to sum rise. With these reason, the high AOD value in spring is mainly due to the impact of long-range (overseas) transport.
The annual mean AOD value is 0.07 with the maximumn value, of 0.2 observed in March. The long-term and monthly trends of AOD and surface extinction coefficients are similar. Suggesting the in-situ measurement can respresent aerosol optical properties through the column. The annual mean AOD in Chung-Li and Chaiyi is around 0.4-0.6, is significnt higher than LABS's. Year variation of high loading month (ie. March) show strongly correlated to climate variability.
Atmospheric Mercury
Atmospheric mercury, occured naturally in coal and other fossil fuels, when people burn these fuels for energy, the mercury becomes airborne and goes into the atmosphere. The main way that people are exposed to mercury is by eating fish and shellfish that have high levels of methylmercury, a highly toxic form of mercury, in their tissues. Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages.
High levels of methylmercury in the bloodstream of babies developing in the womb and young children may harm their developing nervous systems, affecting their ability to think and learn. Birds and mammals that eat fish are have more exposures to methylmercury than other animals in water ecosystems. Predators that eat these birds and mammals are also at risk. Methylmercury has been found in eagles, otters, and endangered Florida panthers. At high levels of exposure, methylmercury's harmful effects on these animals include: death, reduced reproduction, slower growth and development, and abnormal behavior.(Info. from U.S.EPA website)
It is of great concern and undergoing full-scale long-term monitoring. LABS has the longest and leading atmospheric mercury monitoring data in Asia. The average concentration of gaseous mercury (GEM) is 1.69 ng m-3, accounting for 98.7% of the total atmospheric mercury concentration. Besides, the GEM concentrations at LABS is lower in summer (June to July) and higher during autumn to next spring.
