Table 2.
PM2.5 evaluation metrics of the four models.
| TIME | 1AM | 2AM | 3AM | 4AM | 5AM | 6AM | 7AM | 8AM | 9AM | 10AM | 11AM | 12PM | 1PM | 2PM | 3PM | 4PM | 5PM | 6PM | 7PM | 8PM | 9PM | 10PM | 11PM | 12AM | ||
| WINTER | SVM | MAE | 5.23 | 4.44 | 4.00 | 4.02 | 5.55 | 3.61 | 6.44 | 4.58 | 4.23 | 4.73 | 5.04 | 4.62 | 6.38 | 4.73 | 7.85 | 4.78 | 4.06 | 8.54 | 5.41 | 7.52 | 9.04 | 8.51 | 8.98 | 8.66 |
| RMSE | 9.24 | 5.86 | 5.47 | 5.88 | 7.07 | 5.32 | 7.54 | 7.36 | 5.59 | 7.18 | 6.30 | 8.18 | 7.47 | 6.62 | 7.96 | 7.16 | 5.32 | 8.92 | 7.98 | 8.74 | 11.6 | 9.10 | 6.35 | 9.35 | ||
| R2 | 0.44 | 0.54 | 0.58 | 0.48 | 0.51 | 0.76 | 0.56 | 0.63 | 0.72 | 0.76 | 0.63 | 0.50 | 0.53 | 0.40 | 0.43 | 0.46 | 0.45 | 0.35 | 0.51 | 0.39 | 0.46 | 0.44 | 0.54 | 0.88 | ||
| LSTM | MAE | 5.89 | 5.99 | 3.06 | 2.83 | 4.70 | 2.71 | 3.95 | 4.38 | 3.45 | 3.96 | 4.51 | 5.31 | 3.54 | 4.48 | 5.09 | 4.08 | 3.75 | 4.73 | 4.18 | 9.45 | 8.97 | 6.83 | 2.94 | 6.11 | |
| RMSE | 7.60 | 8.31 | 4.28 | 4.97 | 6.52 | 4.40 | 5.52 | 5.71 | 4.00 | 5.74 | 6.25 | 5.84 | 4.38 | 6.22 | 6.89 | 5.49 | 4.93 | 7.57 | 6.11 | 10.1 | 10.4 | 10.8 | 5.13 | 1.91 | ||
| R2 | 0.42 | 0.33 | 0.57 | 0.67 | 0.59 | 0.66 | 0.52 | 0.70 | 0.78 | 0.77 | 0.67 | 0.42 | 0.76 | 0.48 | 0.47 | 0.49 | 0.52 | 0.53 | 0.46 | 0.40 | 0.39 | 0.43 | 0.71 | 0.79 | ||
| SVMF | MAE | 3.64 | 2.64 | 2.93 | 2.24 | 2.33 | 2.18 | 3.97 | 2.86 | 1.89 | 2.02 | 2.49 | 3.46 | 7.76 | 3.76 | 6.00 | 3.70 | 2.47 | 8.33 | 2.88 | 7.45 | 8.20 | 6.77 | 9.10 | 7.63 | |
| RMSE | 4.94 | 3.02 | 4.60 | 4.24 | 4.29 | 3.04 | 5.75 | 3.17 | 2.13 | 4.15 | 3.61 | 3.69 | 7.85 | 4.59 | 7.80 | 4.38 | 4.07 | 9.61 | 4.42 | 8.68 | 10.2 | 7.21 | 9.59 | 7.91 | ||
| R2 | 0.60 | 0.73 | 0.85 | 0.73 | 0.89 | 0.93 | 0.78 | 0.88 | 0.77 | 0.75 | 0.73 | 0.85 | 0.72 | 0.70 | 0.71 | 0.65 | 0.71 | 0.54 | 0.65 | 0.61 | 0.52 | 0.66 | 0.70 | 0.76 | ||
| LSTMF | MAE | 2.07 | 2.51 | 1.82 | 1.85 | 1.83 | 1.61 | 2.09 | 2.04 | 1.17 | 2.02 | 2.24 | 2.23 | 2.22 | 3.63 | 3.10 | 3.06 | 2.11 | 2.16 | 2.88 | 2.08 | 3.64 | 3.58 | 8.63 | 1.87 | |
| RMSE | 3.67 | 3.97 | 3.06 | 2.64 | 3.16 | 2.87 | 3.72 | 2.43 | 1.96 | 3.10 | 3.11 | 3.59 | 3.81 | 3.81 | 4.06 | 3.33 | 3.10 | 3.88 | 4.01 | 2.76 | 3.86 | 3.98 | 9.28 | 8.77 | ||
| R2 | 0.69 | 0.76 | 0.91 | 0.80 | 1.00 | 0.74 | 0.74 | 0.75 | 0.95 | 0.83 | 0.72 | 0.76 | 0.94 | 0.72 | 0.86 | 0.91 | 0.70 | 0.77 | 0.72 | 0.65 | 0.77 | 0.62 | 0.74 | 0.70 | ||
| SPRING | SVM | MAE | 4.96 | 4.70 | 4.40 | 4.45 | 6.01 | 3.92 | 6.76 | 4.81 | 4.52 | 5.36 | 4.79 | 4.58 | 8.01 | 5.86 | 8.48 | 5.65 | 4.86 | ### | 7.26 | 8.08 | 10.3 | 9.51 | 11.82 | 12.17 |
| RMSE | 8.77 | 6.20 | 6.02 | 6.52 | 7.66 | 5.77 | 7.91 | 7.73 | 5.98 | 8.13 | 5.99 | 8.11 | 9.38 | 8.20 | 8.59 | 8.46 | 6.36 | ### | ### | 9.40 | 13.2 | 10.1 | 8.36 | 13.14 | ||
| R2 | 0.46 | 0.52 | 0.54 | 0.45 | 0.48 | 0.72 | 0.54 | 0.61 | 0.68 | 0.70 | 0.66 | 0.51 | 0.44 | 0.34 | 0.41 | 0.41 | 0.39 | 0.26 | 0.38 | 0.36 | 0.40 | 0.39 | 0.41 | 0.63 | ||
| LSTM | MAE | 5.59 | 6.34 | 3.37 | 3.14 | 5.10 | 2.95 | 4.15 | 4.60 | 3.69 | 4.48 | 4.29 | 5.26 | 4.45 | 5.56 | 5.50 | 4.82 | 4.49 | 6.58 | 5.60 | 10.1 | 10.2 | 7.64 | 3.87 | 8.59 | |
| RMSE | 7.21 | 8.79 | 4.72 | 5.51 | 7.06 | 4.78 | 5.79 | 6.00 | 4.28 | 6.50 | 5.94 | 5.79 | 5.51 | 7.71 | 7.44 | 6.49 | 5.90 | ### | 8.20 | 10.9 | 12.0 | 12.1 | 6.76 | 2.69 | ||
| R2 | 0.44 | 0.32 | 0.53 | 0.62 | 0.55 | 0.63 | 0.50 | 0.67 | 0.75 | 0.70 | 0.70 | 0.42 | 0.63 | 0.41 | 0.44 | 0.44 | 0.45 | 0.39 | 0.35 | 0.37 | 0.33 | 0.38 | 0.54 | 0.56 | ||
| SVMF | MAE | 3.45 | 2.79 | 3.22 | 2.48 | 2.52 | 2.37 | 4.17 | 3.01 | 2.02 | 2.29 | 2.37 | 3.43 | 9.74 | 4.66 | 6.48 | 4.37 | 2.96 | ### | 3.87 | 8.01 | 9.39 | 7.56 | 11.97 | 10.72 | |
| RMSE | 4.69 | 3.19 | 5.06 | 4.70 | 4.64 | 3.30 | 6.04 | 3.33 | 2.28 | 4.70 | 3.43 | 3.65 | 9.86 | 5.69 | 8.42 | 5.18 | 4.88 | ### | 5.94 | 9.33 | 11.7 | 8.06 | 12.62 | 11.12 | ||
| R2 | 0.63 | 0.70 | 0.79 | 0.68 | 0.84 | 0.88 | 0.76 | 0.85 | 0.73 | 0.68 | 0.76 | 0.86 | 0.60 | 0.58 | 0.68 | 0.57 | 0.62 | 0.40 | 0.49 | 0.56 | 0.44 | 0.58 | 0.53 | 0.55 | ||
| LSTMF | MAE | 1.96 | 2.65 | 2.01 | 2.05 | 1.99 | 1.75 | 2.19 | 2.14 | 1.25 | 2.29 | 2.13 | 2.21 | 2.78 | 4.50 | 3.35 | 3.61 | 2.53 | 3.02 | 3.87 | 2.24 | 4.17 | 4.00 | 11.35 | 2.64 | |
| RMSE | 3.49 | 4.21 | 3.37 | 2.93 | 3.42 | 3.12 | 3.90 | 2.55 | 2.10 | 3.51 | 2.95 | 3.56 | 4.78 | 4.72 | 4.38 | 3.93 | 3.71 | 5.40 | 5.38 | 2.97 | 4.42 | 4.44 | 12.21 | 12.33 | ||
| R2 | 0.72 | 0.73 | 0.85 | 0.74 | 0.94 | 0.70 | 0.71 | 0.72 | 0.90 | 0.76 | 0.74 | 0.77 | 0.78 | 0.60 | 0.81 | 0.81 | 0.61 | 0.57 | 0.55 | 0.60 | 0.66 | 0.54 | 0.56 | 0.50 | ||
| SUMMER | SVM | MAE | 5.03 | 4.56 | 4.32 | 4.84 | 6.30 | 4.14 | 7.48 | 4.78 | 4.20 | 5.00 | 7.43 | 6.56 | 6.50 | 4.66 | 7.92 | 5.16 | 4.03 | 8.64 | 5.54 | 6.97 | 7.51 | 7.09 | 8.62 | 9.04 |
| RMSE | 8.88 | 6.01 | 5.91 | 7.09 | 8.03 | 6.10 | 8.75 | 7.68 | 5.56 | 7.58 | 9.29 | 11.6 | 7.61 | 6.53 | 8.02 | 7.73 | 5.28 | 9.02 | 8.16 | 8.10 | 9.64 | 7.58 | 6.09 | 9.76 | ||
| R2 | 0.46 | 0.53 | 0.55 | 0.42 | 0.46 | 0.69 | 0.50 | 0.61 | 0.72 | 0.74 | 0.41 | 0.35 | 0.53 | 0.40 | 0.43 | 0.44 | 0.46 | 0.35 | 0.50 | 0.42 | 0.54 | 0.52 | 0.56 | 0.85 | ||
| LSTM | MAE | 5.66 | 6.15 | 3.31 | 3.41 | 5.34 | 3.11 | 4.59 | 4.57 | 3.43 | 4.18 | 6.65 | 7.54 | 3.61 | 4.42 | 5.13 | 4.40 | 3.72 | 4.78 | 4.28 | 8.76 | 7.45 | 5.69 | 2.82 | 6.38 | |
| RMSE | 7.30 | 8.52 | 4.63 | 5.99 | 7.40 | 5.05 | 6.41 | 5.96 | 3.97 | 6.06 | 9.20 | 8.29 | 4.46 | 6.14 | 6.95 | 5.93 | 4.90 | 7.65 | 6.25 | 9.43 | 8.72 | 9.05 | 4.93 | 2.00 | ||
| R2 | 0.44 | 0.33 | 0.54 | 0.58 | 0.53 | 0.60 | 0.46 | 0.67 | 0.79 | 0.74 | 0.44 | 0.29 | 0.75 | 0.49 | 0.46 | 0.47 | 0.52 | 0.52 | 0.45 | 0.43 | 0.45 | 0.50 | 0.73 | 0.76 | ||
| SVMF | MAE | 3.50 | 2.71 | 3.16 | 2.70 | 2.64 | 2.50 | 4.61 | 2.99 | 1.88 | 2.13 | 3.67 | 4.91 | 7.90 | 3.71 | 6.05 | 4.00 | 2.45 | 8.43 | 2.95 | 6.91 | 6.81 | 5.64 | 8.73 | 7.96 | |
| RMSE | 4.75 | 3.09 | 4.97 | 5.12 | 4.87 | 3.49 | 6.68 | 3.31 | 2.12 | 4.38 | 5.32 | 5.23 | 7.99 | 4.53 | 7.86 | 4.73 | 4.04 | 9.72 | 4.53 | 8.05 | 8.52 | 6.01 | 9.20 | 8.26 | ||
| R2 | 0.62 | 0.72 | 0.80 | 0.63 | 0.81 | 0.84 | 0.70 | 0.85 | 0.77 | 0.72 | 0.48 | 0.60 | 0.71 | 0.70 | 0.71 | 0.61 | 0.71 | 0.53 | 0.64 | 0.65 | 0.61 | 0.77 | 0.72 | 0.74 | ||
| LSTMF | MAE | 1.99 | 2.57 | 1.97 | 2.23 | 2.08 | 1.85 | 2.42 | 2.13 | 1.16 | 2.14 | 3.30 | 3.17 | 2.26 | 3.58 | 3.13 | 3.30 | 2.10 | 2.19 | 2.95 | 1.93 | 3.02 | 2.98 | 8.28 | 1.96 | |
| RMSE | 3.53 | 4.08 | 3.31 | 3.19 | 3.59 | 3.29 | 4.32 | 2.54 | 1.95 | 3.28 | 4.58 | 5.10 | 3.88 | 3.76 | 4.09 | 3.59 | 3.08 | 3.92 | 4.11 | 2.56 | 3.21 | 3.31 | 8.91 | 9.16 | ||
| R2 | 0.72 | 0.75 | 0.86 | 0.70 | 0.90 | 0.68 | 0.66 | 0.72 | 0.95 | 0.80 | 0.47 | 0.53 | 0.93 | 0.72 | 0.85 | 0.87 | 0.71 | 0.76 | 0.71 | 0.70 | 0.90 | 0.72 | 0.76 | 0.67 | ||
| AUTUMN | SVM | MAE | 5.60 | 5.10 | 4.05 | 4.07 | 5.24 | 3.63 | 6.05 | 4.11 | 3.82 | 4.70 | 4.54 | 4.40 | 6.24 | 4.76 | 7.79 | 5.09 | 4.12 | 8.62 | 5.28 | 6.04 | 7.46 | 7.01 | 9.69 | 8.97 |
| RMSE | 9.90 | 6.73 | 5.54 | 5.95 | 6.68 | 5.34 | 7.08 | 6.60 | 5.06 | 7.13 | 5.68 | 7.79 | 7.31 | 6.66 | 7.90 | 7.62 | 5.39 | 9.00 | 7.78 | 7.03 | 9.58 | 7.49 | 6.85 | 9.69 | ||
| R2 | 0.41 | 0.49 | 0.57 | 0.48 | 0.52 | 0.76 | 0.58 | 0.68 | 0.77 | 0.77 | 0.68 | 0.52 | 0.54 | 0.40 | 0.43 | 0.44 | 0.45 | 0.35 | 0.51 | 0.47 | 0.55 | 0.52 | 0.51 | 0.85 | ||
| LSTM | MAE | 6.31 | 6.88 | 3.10 | 2.86 | 4.44 | 2.73 | 3.71 | 3.93 | 3.12 | 3.93 | 4.07 | 5.05 | 3.47 | 4.51 | 5.05 | 4.34 | 3.80 | 4.77 | 4.08 | 7.60 | 7.40 | 5.63 | 3.17 | 6.34 | |
| RMSE | 8.14 | 9.53 | 4.34 | 5.03 | 6.16 | 4.42 | 5.19 | 5.12 | 3.62 | 5.70 | 5.63 | 5.56 | 4.29 | 6.26 | 6.84 | 5.84 | 5.00 | 7.64 | 5.96 | 8.18 | 8.66 | 8.95 | 5.54 | 1.98 | ||
| R2 | 0.40 | 0.30 | 0.57 | 0.67 | 0.61 | 0.66 | 0.54 | 0.75 | 0.84 | 0.77 | 0.72 | 0.43 | 0.77 | 0.48 | 0.47 | 0.47 | 0.51 | 0.52 | 0.47 | 0.48 | 0.45 | 0.51 | 0.67 | 0.77 | ||
| SVMF | MAE | 3.90 | 3.03 | 2.96 | 2.27 | 2.20 | 2.19 | 3.73 | 2.57 | 1.71 | 2.00 | 2.25 | 3.29 | 7.59 | 3.78 | 5.96 | 3.94 | 2.50 | 8.41 | 2.81 | 5.99 | 6.77 | 5.57 | 9.82 | 7.91 | |
| RMSE | 5.29 | 3.46 | 4.66 | 4.29 | 4.05 | 3.05 | 5.41 | 2.84 | 1.93 | 4.12 | 3.25 | 3.51 | 7.68 | 4.62 | 7.74 | 4.66 | 4.13 | 9.70 | 4.32 | 6.98 | 8.46 | 5.94 | 10.35 | 8.20 | ||
| R2 | 0.57 | 0.65 | 0.84 | 0.72 | 0.93 | 0.93 | 0.81 | 0.95 | 0.82 | 0.75 | 0.79 | 0.88 | 0.73 | 0.69 | 0.72 | 0.62 | 0.70 | 0.54 | 0.66 | 0.73 | 0.61 | 0.77 | 0.65 | 0.74 | ||
| LSTMF | MAE | 2.22 | 2.88 | 1.85 | 1.87 | 1.73 | 1.62 | 1.96 | 1.83 | 1.05 | 2.01 | 2.02 | 2.13 | 2.17 | 3.65 | 3.08 | 3.25 | 2.14 | 2.18 | 2.81 | 1.68 | 3.00 | 2.95 | 9.31 | 1.94 | |
| RMSE | 3.94 | 4.56 | 3.10 | 2.68 | 2.98 | 2.88 | 3.49 | 2.18 | 1.78 | 3.08 | 2.80 | 3.42 | 3.73 | 3.84 | 4.03 | 3.54 | 3.14 | 3.91 | 3.91 | 2.22 | 3.19 | 3.27 | 10.01 | 9.09 | ||
| R2 | 0.65 | 0.68 | 0.90 | 0.79 | 0.94 | 0.74 | 0.77 | 0.80 | 0.95 | 0.83 | 0.77 | 0.79 | 0.95 | 0.71 | 0.86 | 0.88 | 0.70 | 0.76 | 0.74 | 0.78 | 0.90 | 0.73 | 0.69 | 0.68 |