Scatter plots of radiation temperatures derived from various near and far ultraviolet line-features from IRIS versus those obviated with ALMA at 1.3 mm. The plots represent the pixel-to-pixel relationships for the pixel where their samling time difference are equal to or smaller than two minutes, corresponding to the blue hatched area in Fig. 4f. The colours represent density of the scatter points (with the highest density number being coloured red and the lowest density dark blue). At each plot, the regression slope of the linear fit (m), the Pearson correlation coefficient (r), and the Spearman’s rank correlation coefficient (ρ) are also indicated.