Fig. 2: Precipitation in simulations and observations.

Time series of accumulated precipitation (mm) from observations and simulations averaged over (a) sea and (b) land. The green solid line represents the TRMM3B42v7. The orange, blue, black, and red solid lines depict precipitation from the very-low-aerosol, low-aerosol, control, and high-aerosol runs, respectively, while the dashed lines represent precipitation from the low-aerosol-norad (blue), control-norad (black), and high-aerosol-norad (red) runs. Here, ‘norad’ refers to simulations without direct aerosol radiative effects. The abscissa indicates the simulation period, from December 1st to December 4th, 2011. The ordinate represents accumulated precipitation in each time step. TRMM3B42 (simulations) has a 3-hour (1-hour, respectively) temporal resolution. c Percentage change in precipitation (%) for each experiment relative to the very-low-aerosol run over the sea (red) and land (blue). Observed daily precipitation and MERRA-2 AOD averaged separately for (d) sea and (e) land during October to February for El Niño-Southern Oscillation (ENSO)-neutral years 2001, 2003, 2012, and 2013 (i.e., El Nino and La Nina years are excluded to avoid their influence). The correlation coefficients are also shown; based on the average e-folding timescale (approximately 6 days) from the autocorrelation of the AODs, these values are significant at the 95% confidence level. The orange and green dots represent aerosol days having upper 5% and lower 5% AOD conditions (high-AOD and low-AOD, respectively). The events are used to plot Fig. 6c, d. f Observed (TRMM3B42v7) percentage change in precipitation (%) for sea (red) and land (blue) relative to very low-aerosol events (AOD values less than 0.13).