| dc.description.abstract | The structure of planetary boundary layer (PBL) changes in a day and influences the concentration of low-altitude pollutants. However, the traditional routine radiosonde observation is conducted only twice a day and can not resolve the diurnal variation of the atmosphere. In recent years, miniature radiosonde systems were developed to meet the need of intensive observation. Thus, we developed a miniature radiosonde system with measurement of PM2.5 in this research, and name it Aerosond.
We improved the design of temperature and relative humidity sensors of Aerosond and upgraded its GPS sensor, to release four versions of Aerosond during 2021-2023. Every version of Aerosond conducted the data quality validation experiments with Vaisala RS-41 radiosonde. The results of data quality validation experiments showed that under 3 km, the latest version of Aerosond has a mean absolute error of temperature with 0.6°C (nighttime temperature of 0.2°C), relative humidity with 4.5%, wind speed with 0.3 m s-1, and wind direction with 7°.
Because weak synoptic weather made air quality worse in Central and Southern Taiwan in winter and spring, T-POMDA experiment was held to study the interaction between meteorology and air pollution. Aerosond were applied in T-POMDA experiment to have intensive observation under four air pollution events in central and southern Taiwan during 2021-2023. Vertical profile data indicate that the meteorological factors which lead air pollutants accumulated within PBL including low horizontal wind speeds, stronger radiative cooling intensity, and high atmospheric stability. Coastal regions and inland regions have different characteristics under air pollution events. In coastal regions, inversion layer may exist the whole day and lead to high PM2.5 concentration at near-surface. In daytime of inland regions, the atmospheric stability is lower than coastal regions and let PM2.5 disperse to higher altitude. Whereas in nighttime of inland region, there has strong inversion intensity and make PM2.5 accumulate in low altitude. During intensive observation period, bulk Richardson number method can provide us reasonable PBL height. It’s also worth mentioning that Aerosond’s data can be used to identify the height and concentration of long-range transported biomass burning PM2.5 from Peninsular Southeast Asia in free atmosphere, because Aerosond can cover the observation under 10 km.
The results of data quality validation experiments and the results of T-POMDA experiments indicates that Aerosond can provide reliable data, and can help us to study how atmospheric structure affects the distribution of PM2.5. Aerosond’s data can validate numerical model or be applied in data assimilation in the future. | en_US |