Fig. 8: Comparison of the average latitude-weighted RMSE (first and second rows) and ACC (third and fourth rows) of the 139 sets of 7-day’s medium forecast using ERA5 and outputs of 4DVarFormer (red lines for using 3-day forecasting background filed as 4DVarFormer’s input, blue lines for 4-day forecasting background field as the input, and yellow lines for 5-day forecasting background field as the input).

Four surface variables, such as MSLP, T2M, U10, and V10, and six upper-air variables are illustrated, including Z500, T850, T500, R500, U500, V500, using testing data from 2021 to 2022. All models are evaluated against the ERA5 reanalysis dataset.