Figure 3

Left panels: time series of the area-averaged 2-m temperatures for (a) SC and (b) WE. The corresponding areas are defined by the boxes shown in Fig. 1a. Parameters shown are daily 2-m temperature (T2), long-term daily mean (T2C), daily 2-m temperature anomalies (aT2), and modified excess heat factor (EHF). Dots indicate the daily 2-m temperature exceed the 90th percentile threshold. Units: °C. The reference period is 1999–2010 for the calculation of aT2 and EHF. Gray shading region covers the period of 12 July–8 August, 2018. Right panels: Pearson correlation coefficients of daily anomalies of 2-m temperature (shading, °C) and 500-hPa geopotential height (contour, m) with the area-averaged temperatures for (c) SC and (d) WE. Solid and dashed contours for positive and negative correlation coefficients, respectively. Contour interval is 2, and zero contours are omitted. The correlation coefficients were calculated for period of 1 July–31 August, 2018. The maps were generated using software NCAR Command Language (https://www.ncl.ucar.edu/)³² with the built-in Ncarg4_0 database.