Development of Korean Air Quality Prediction System version 1 (KAQPS v1) with focuses on practical issues

Abstract

Abstract. For the purpose of providing reliable and robust air quality predictions, an air quality prediction system was developed for the main air quality criteria species in South Korea (PM10, PM2.5, CO, O3 and SO2). The main caveat of the system is to prepare the initial conditions (ICs) of the Community Multiscale Air Quality (CMAQ) model simulations using observations from the Geostationary Ocean Color Imager (GOCI) and ground-based monitoring networks in northeast Asia. The performance of the air quality prediction system was evaluated during the Korea-United States Air Quality Study (KORUS-AQ) campaign period (1 May–12 June 2016). Data assimilation (DA) of optimal interpolation (OI) with Kalman filter was used in this study. One major advantage of the system is that it can predict not only particulate matter (PM) concentrations but also PM chemical composition including five main constituents: sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic aerosols (OAs) and elemental carbon (EC). In addition, it is also capable of predicting the concentrations of gaseous pollutants (CO, O3 and SO2). In this sense, this new air quality prediction system is comprehensive. The results with the ICs (DA RUN) were compared with those of the CMAQ simulations without ICs (BASE RUN). For almost all of the species, the application of ICs led to improved performance in terms of correlation, errors and biases over the entire campaign period. The DA RUN agreed reasonably well with the observations for PM10 (index of agreement IOA =0.60; mean bias MB =-13.54) and PM2.5 (IOA =0.71; MB =-2.43) as compared to the BASE RUN for PM10 (IOA =0.51; MB =-27.18) and PM2.5 (IOA =0.67; MB =-9.9). A significant improvement was also found with the DA RUN in terms of bias. For example, for CO, the MB of −0.27 (BASE RUN) was greatly enhanced to −0.036 (DA RUN). In the cases of O3 and SO2, the DA RUN also showed better performance than the BASE RUN. Further, several more practical issues frequently encountered in the air quality prediction system were also discussed. In order to attain more accurate ozone predictions, the DA of NO2 mixing ratios should be implemented with careful consideration of the measurement artifacts (i.e., inclusion of alkyl nitrates, HNO3 and peroxyacetyl nitrates – PANs – in the ground-observed NO2 mixing ratios). It was also discussed that, in order to ensure accurate nocturnal predictions of the concentrations of the ambient species, accurate predictions of the mixing layer heights (MLHs) should be achieved from the meteorological modeling. Several advantages of the current air quality prediction system, such as its non-static free-parameter scheme, dust episode prediction and possible multiple implementations of DA prior to actual predictions, were also discussed. These configurations are all possible because the current DA system is not computationally expensive. In the ongoing and future works, more advanced DA techniques such as the 3D variational (3DVAR) method and ensemble Kalman filter (EnK) are being tested and will be introduced to the Korean air quality prediction system (KAQPS).

Highly resolved mapping of NO2 vertical column densities from GeoTASO measurements over a megacity and industrial area during the KORUS-AQ campaign

“…Besides anthropogenic and biogenic emissions, the Fire Inventory from NCAR (FINN; Wiedinmyer et al, 2006Wiedinmyer et al, , 2011 was utilised to update the pyrogenic emission fields. Details of the model descriptions have been provided by Lee et al (2020).…”

Correcting model biases of CO in East Asia: impact on oxidant distributions during KORUS-AQ

“…While the emission update improves the forecast closer to the source, the assimilation allows for better reproduction of the vertical profiles and the background and eventually compensates for model errors. Lee et al 2020) or global (Barré et al, 2019) air quality analysis and forecasting systems. Further improvements can be achieved by simultaneously assimilating CH 2 O retrievals (e.g.…”

Assessing CALIOP-Derived Planetary Boundary Layer Height Using Ground-Based Lidar

“…The planetary boundary layer (PBL), as the lowest part of the troposphere, plays an important role in the exchanges of energy, momentum, moisture, gases, and aerosols between the earth surface and free atmosphere [1]. The PBL height (PBLH), therefore, is a key parameter in air quality modeling, as PBL disperses surface-emitted pollutants and acts as a barrier to the pollutants by preventing their transport to the free atmosphere [2][3][4][5]. As aerosols tend to mix well in PBL, especially for convective PBL conditions during daytime, and the aerosol concentration rapidly decreases above PBL, both ground-based and spaceborne lidar measurements have been widely used for PBLH detection (e.g., [6][7][8][9][10]).…”