This study introduces the Southern Particulate Matter Supersite in Taiwan, which began operating on April 1, 2005. The supersite has one core station and three satellite stations for monitoring the properties of particulate matter (PM) and emission sources in southern Taiwan. High-time resolution(1-30 minutes) data for physical and chemical properties of ambient PM are acquired continuously.Measurement data are as follows: (1) PM 2.5 (PM with aerodynamic diameters < 2.5 μm) and PM 10 (PM with aerodynamic diameters < 10 μm) mass concentrations; (2) PM 2.5 compositions of sulfate, nitrate and carbon; (3) particle light scattering and absorption; (4) particle number concentrations in various size fractions between 10 nm and 20 μm; (5) related precursor gases such as NO y , H 2 O 2 , and NH 3 ; and, (6) meteorological variables. Most measurements are unique to the study area and can be used to elucidate the causes of PM pollution and evaluate PM exposure and adverse health effects. In addition to describing the sampling location, measurements and data archiving, future challenges for the supersite are discussed as well.

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[1] This work examines how ozone-laden sea breeze air masses contribute to inland surface ozone concentrations. The vertical distributions of ozone in sea breeze air masses and the characteristics of sea breezes are investigated using tethered ozonesondes and meteorological radiosondes, respectively, at a measurement site near the northern coast of Taiwan during 24-30 August 2003. The investigations reveal that, initially, sea breeze air masses are stable with relatively high concentrations of ozone distributed in the upper portions of the air masses. Elevated ozone layers with concentrations of 60-100 ppb were frequently observed at 500-1600 m. The growth of a thermal internal boundary layer (TIBL) inland that can bring ozone-rich air aloft in a sea breeze air mass into the growing TIBL subsequently increases the surface ozone concentrations farther inland. Accordingly, the surface ozone concentrations increase with distance inland, regardless of the photochemical production of ozone inland. A new conceptual model was presented to depict this pollution feature. According to a simple Lagrangian analysis, ozone-rich sea breeze air masses under the observed conditions generated a difference of as much as a 30 ppb between the surface ozone concentration at a near-coast location and that at a far inland location. TIBL development at a near-coast area can protect the area from fumigation of elevated ozone layers because the depth of the TIBL is limited there, such that the ozone in the elevated ozone layers cannot be brought to the ground.

This work presents the vertical distributions of ozone and meteorological parameters observed with tethered ozonesondes and meteorological radiosondes in the lower atmosphere during an ozone episode on March 25-27, 2003, in Kaohsiung City in southern Taiwan. Kaohsiung is a coastal industrial city with inland mountain ranges to the east. Extremely complicated ozone structures were identified that spanned day and night during the experimental period. During afternoons, the lower atmosphere was divided into two stratified air layers with substantially different ozone concentrations. On the episode day (March 26), average ozone concentration in the near-ground layer was 85 ppb and the aloft layer was 140 ppb. A very high ozone peak of 199 ppb measured aloft likely resulted from an elevated large point source. Several no-ozone air layers, distributed throughout 400-750 m, were observed to transport on shore during the night. As well, elevated ozone layers peaking at 60-90 ppb and 90-160 ppb were detected below and above the no-ozone air layers, respectively. These complicated ozone structures were likely formed through titration of plumes from large point sources and the circulations of sea breezes or combined sea-breeze/mountain flows in the study area.

Linyuan (LY) is a coastal sta tion lo cated down wind of the in dus trial city of Kaohsiung in south ern Tai wan. This sta tion is of ten af fected by se vere ozone pol lu tion dur ing sea breeze events. In ten sive teth ered ozone soundings were per formed at this sta tion dur ing a 4-day ozone ep i sode in No vem ber, 2005. Back air tra jec to ries were also cal cu lated to track the or i gins of air masses ar riv ing at the sta tion dur ing the ex per i ment. The in ves ti ga tion re vealed com pli cated ozone pro files in the lower at mo sphere (be low 1300 m) both day and night. At night, in dus trial plumes form ing no-ozone air lay ers were fre quently dis trib uted at 400-800 m. Mix ing lay ers rap idly de creased from 800-1100 m down to 200-350 m in the late morn ing hours when sea breezes and ther mal in ter nal bound ary lay ers (TIBLs) de vel oped. Recirculation of pol luted in land air masses over the sea, the de vel op ment of TIBLs, and the late de vel op ment of sea-breeze events all are likely re spon si ble for se vere ozone pol lu tion at the LY sta tion. El e vated in dus trial plumes or ozone aloft above TIBLs re vealed only a mi nor con tri bu tion to ozone pol lu tion via a down ward mix ing pro cess. El e vated ozone lev els (140-170 ppb) were of ten trapped within tran si tional lay ers of sea-breeze cir cu la tions at 600-800 m and were ac com pa nied by am bi ent north erly flows par al lel to the coast line, sug gest ing that an ozone pol lu tion core likely formed over the west coast of Taiwan on ozone-episodic days when sea-breeze circulations developed.