Fig. 3: Simulated low-cloud enhancement by semi-direct effect of biomass-burning aerosols in subtropical southeastern Asia.

a Monthly averaged difference of low cloud fraction plotted with winds at an altitude of 1 km in March of high aerosol optical depth (AOD) years. b Spatial patterns of black carbon (BC) concentrations and aerosol-induced atmospheric heating rate at the altitude of 3 km (red isolines with the unit of K day⁻¹) in March of high-AOD years. c Vertical cross-section of BC concentration, cloud enhancement and air temperature difference (red contours for heating and blue contours for dimming, unit: K) along the coastal region (17°N–23°N) for the runs with ARI effect on/off in March of high-AOD years (2004, 2007, 2010, and 2014). d–f, Same as a–c but for low-AOD years (2001, 2003, 2005, 2011). The results are calculated from the difference between simulations with and without considering aerosol–radiation interaction (EXP_ARI and EXP_exAR). Note: Gray isolines in (a) and (d) show topography (unit: km) and black dots mark the grids passing a T-test. Green lines in (c) and (f) show the boundary layer height at 6:00 UTC. The black circle in (b) shows the location of Nanning.