Fig.1

The temporal variation of the number of stations experiencing late spring cold events (a) and the k-value (b) in Chongqing from 1991 to 2020"

Table 1

The total number of stations with late spring cold events, the number of stations by each level, the k-value, the average spring temperature, and their anomaly values for different periods in Chongqing from 1991 to 2020"

Fig.2

Spatial distribution of the number of late spring cold events (a) and the annual average k-value (b) in Chongqing from 1991 to 2020"

Fig.3

Spatial distribution of the first (a) and second (b) EOF modes of the frequency of late spring cold events and annual variation of temporal coefficients of the first and second EOF modes (c) in Chongqing from 1991 to 2020"

Fig.4

Circulation patterns and anomalies of the spring 500 hPa height in years with high (a) and low (b) frequency of late spring cold events, the difference in 500 hPa height between high-frequency and low-frequency years (c), and correlation coefficient distribution between the number of stations with late spring cold events and the 500 hPa height (d) in Chongqing from 1991 to 2020"

Fig.5

Circulation patterns and anomalies of the spring 700 hPa temperature in years with high (a) and low (b) frequency of late spring cold events, the difference in 700 hPa temperature between high-frequency and low-frequency years (c), and correlation coefficient distribution between the number of stations with late spring cold events and the 700 hPa temperature (d) in Chongqing from 1991 to 2020"

Fig.6

Zonal wind and anomalies of the spring 200 hPa in years with high (a) and low (b) frequency of late spring cold events, the difference in 200 hPa zonal wind between high-frequency and low-frequency years (c), and correlation coefficient distribution between the number of stations with late spring cold events and the 200 hPa zonal wind (d) in Chongqing from 1991 to 2020"

Fig.7

The anomalies of spring 850 hPa wind in years with high (a) and low (b) frequency of late spring cold events, and correlation coefficient distribution between the number of stations with late spring cold events and the 850 hPa wind (c) in Chongqing from 1991 to 2020"

Fig.8

Correlation coefficient field between the number of stations experiencing late spring cold events and sea surface temperatures during the previous summer (a), autumn (b), and winter (c) in Chongqing from 1991 to 2020"

Table 2

Correlation coefficients between late spring cold events and spring index in Chongqing from 1991 to 2020"