Table 1.
Differences in key meteorological parameters between haze days and clean days.
| Polluted days | Clean days | ||||||
|---|---|---|---|---|---|---|---|
| Region | Meteorological parameter | Mean | Std | Mean | Std | Difference | P-value (bootstrap) |
| BTH | RH a | 76.5 | 8.1 | 56.5 | 10.2 | 20.0 | <0.001 |
| SLP b | 102 429.7 | 513.9 | 103 181.1 | 501.1 | –751.4 | <0.001 | |
| T_2m c | 269.9 | 4.5 | 263.3 | 5.8 | 6.6 | <0.001 | |
| ws_10m d | 2.7 | 1.1 | 4.4 | 1.4 | –1.7 | <0.001 | |
| u_10m e | 1.1 | 1.4 | 2.8 | 1.4 | –1.7 | <0.001 | |
| v_10m f | –0.4 | 1.9 | –2.7 | 1.9 | 2.3 | <0.001 | |
| delT_925_1000 g | –1.9 | 1.2 | –3.1 | 0.5 | 1.1 | <0.001 | |
| BLH h | 221.4 | 50.9 | 562.8 | 191.8 | –341.4 | <0.001 | |
| hgt_500 i | 5561.3 | 74.2 | 5469.5 | 90.8 | 91.8 | <0.001 | |
| omega_850 j | 4.1E-2 | 5.7E-2 | 18.8E-2 | 7.1E-2 | −14.7E-2 | <0.001 | |
| YRD | RH | 75.5 | 9.5 | 62.5 | 11.0 | 13.0 | <0.001 |
| SLP | 102 261.1 | 410.0 | 102 948.5 | 475.6 | –687.4 | <0.001 | |
| T_2m | 281.8 | 3.8 | 276.4 | 5.8 | 5.4 | <0.001 | |
| ws_10m | 2.6 | 0.9 | 3.7 | 1.1 | –1.1 | <0.001 | |
| u_10m | –0.4 | 1.3 | 0.4 | 1.7 | –0.8 | 0.0014 | |
| v_10m | –0.4 | 1.8 | –1.8 | 2.1 | 1.4 | <0.001 | |
| delT_925_1000 | –2.1 | 0.9 | –2.9 | 1.0 | 0.8 | <0.001 | |
| BLH | 316.7 | 73.5 | 498.3 | 148.6 | –181.6 | <0.001 | |
| hgt_500 | 5689.7 | 52.0 | 5665.4 | 76.8 | 24.4 | 0.0285 | |
| omega_850 | 2.1E-2 | 3.9E-2 | 7.6E-2 | 4.7E-2 | −5.6E-2 | <0.001 | |
| PRD | RH | 75.5 | 12.5 | 62.2 | 13.3 | 13.2 | <0.001 |
| SLP | 101 762.2 | 272.0 | 102 388.3 | 363.3 | –626.1 | <0.001 | |
| T_2m | 290.1 | 2.6 | 285.3 | 4.0 | 4.8 | <0.001 | |
| ws_10m | 2.6 | 0.8 | 4.6 | 1.1 | –2.0 | <0.001 | |
| u_10m | –1.5 | 0.6 | –2.3 | 0.6 | 0.8 | <0.001 | |
| v_10m | –0.7 | 1.7 | –3.7 | 1.6 | 3.0 | <0.001 | |
| delT_925_1000 | –3.3 | 0.6 | –3.0 | 0.8 | –0.3 | 0.0402 | |
| BLH | 356.7 | 69.1 | 526.7 | 144.1 | –170.0 | <0.001 | |
| hgt_850 | 1529.2 | 19.0 | 1554.3 | 14.7 | –25.2 | <0.001 | |
| omega_850 | −2.3E-2 | 4.8E-2 | 5.7E-2 | 4.6E-2 | −8.0E-2 | <0.001 | |
| SCB | RH | 67.1 | 9.8 | 69 | 12.2 | –1.96 | 0.1747 |
| SLP | 102 301.3 | 583.5 | 102 813.0 | 572.9 | –511.7 | <0.001 | |
| T_2m | 277.8 | 3.3 | 275.1 | 4.3 | 2.6 | <0.001 | |
| ws_10m | 2.3 | 0.7 | 2.2 | 0.8 | 0.1 | 0.1825 | |
| u_10m | –1.1 | 1.3 | –1.2 | 1.2 | 0.1 | 0.6488 | |
| v_10m | –0.1 | 1.0 | –0.1 | 1.0 | 0.0 | 0.8998 | |
| delT_925_1000 | –3.8 | 0.3 | –3.9 | 0.3 | 0.2 | <0.001 | |
| BLH | 304.1 | 61.0 | 406.0 | 122.3 | –101.8 | <0.001 | |
| hgt_850 | 1526.0 | 40.3 | 1556.3 | 37.9 | –30.3 | <0.001 | |
| omega_500 | 2.8E-2 | 9.3E-2 | 6.3E-2 | 8.7E-2 | −3.5E-2 | 0.0044 | |
aRelative humidity, in unit of %.
bSea-level pressure, in unit of Pa.
cTemperature at 2 m, in unit of K.
dWind speed at 10 m, in unit of m/s.
eZonal wind speed at 10 m, in unit of m/s.
fMeridional wind speed at 10 m, in unit of m/s.
gTemperature difference between 925 and 1000 hPa (T@925–T@1000), in unit of K.
hBoundary layer height, in unit of m.
iGeopotential height at 500 hPa, in unit of m.
jVertical velocity at 850 hPa, in unit of Pa/s.