Fig.1

Topography and site location of the study area"

Fig.2

The number of visibility stations of different classes in Shaanxi province from January 11 to 13, 2019 (a) and the spatial distribution of the lowest visibility from 08:00 on January 11 to 08:00 on January 12 (b)"

Fig.3

Visibility changes at partial stations Lintong (a), Huazhou (b), HuaYin (c), Zhouzhi (d), Dali (e), Jinghe (f), Huyi (g), Gaoling (h) in Shaanxi province from 20:00 on January 10, 2019, to 20:00 on January 12, 2019"

Fig.4

Changes in temperature and dew point temperature (a), relative humidity and water vapor pressure (b), wind direction and wind speed (c), and visibility (d) at Jinghe station from 20:00 on January 10, 2019, to 20:00 on January 12, 2019"

Fig.5

High altitude situation field at 500 hPa at 08:00 on the 10th (a), high altitude situation field at 500 hPa (b) and surface pressure field (c) at 08:00 on the 11th, high altitude situation field at 850 hPa at 20:00 on the 11th (d), January 2019"

Fig.6

Vertical temperature and humidity profile of Jinghe Station at 20:00 on the 10th (a), 8:00 on the 11th (b), 20:00 on the 11th (c), 8:00 on the 12th (d) January, 2019"

Fig.7

The spatial distribution of the averaged steady index (a) and the averaged visibility (b) over Guanzhong Plain, Shaanxi from 20:00 on January 10, 2019, to 10:00 on January 11, 2019"

Fig.8

Vertical cross sections of water vapor flux and water vapor flux divergence at Jinghe station from 08:00 on the 10th to 07:00 on the 11th, January 2019 (a) and from 08:00 on the 11th to 07:00 on the 12th (b), vertical velocity and terrain along longitude 109°E at 22:00 on the 10th (c) and at 06:00 on the 11th (d) January 2019"

Fig.9

Spatial distribution of visibility (a, c) and terrain overlay with wind field divergence (b, d) distribution over Guanzhong Plain, Shaanxi at 00:00 and 23:00 on January 11, 2019"

Fig.10

The 925 hPa temperature advection at 06:00 (a) and the 925 hPa water vapor flux and its divergence at 22:00 (b) on January 11, 2019"