Statistical Seasonal Forecasting of Winter and Spring PM(2.5) Concentrations Over the Korean Peninsula

Concentrations of fine particulate matter smaller than 2.5 μm in diameter (PM(2.5)) over the Korean Peninsula experience year-to-year variations due to interannual variation in climate conditions. This study develops a multiple linear regression model based on slowly varying boundary conditions to predict winter and spring PM(2.5) concentrations at 1–3-month lead times. Nation-wide observations of Korea, which began in 2015, is extended back to 2005 using the local Seoul government’s observations, constructing a long-term dataset covering the 2005–2019 period. Using the forward selection stepwise regression approach, we identify sea surface temperature (SST), soil moisture, and 2-m air temperature as predictors for the model, while rejecting sea ice concentration and snow depth due to weak correlations with seasonal PM(2.5) concentrations. For the wintertime (December–January–February, DJF), the model based on SSTs over the equatorial Atlantic and soil moisture over the eastern Europe along with the linear PM(2.5) concentration trend generates a 3-month forecasts that shows a 0.69 correlation with observations. For the springtime (March–April–May, MAM), the accuracy of the model using SSTs over North Pacific and 2-m air temperature over East Asia increases to 0.75. Additionally, we find a linear relationship between the seasonal mean PM(2.5) concentration and an extreme metric, i.e., seasonal number of high PM(2.5) concentration days. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13143-022-00275-4.