Rain-Aerosol Relationships Influenced by Wind Speed
Aerosol optical depth (AOD) has been shown to correlate with precipitation rate (R) in recent studies. The R-AOD relationships over oceans are examined in this study using 150-year simulations with the CESM model. Through partial correlation analysis, with the influence of 10-m wind speed removed, R-AOD relationships exert a change from positive to negative over the mid-latitude oceans, indicating that wind speed makes a large contribution to the relationships by changing the sea salt emissions. A simulation with prescribed sea-salt emissions shows that wind speed lead to increasing R by +0.99 mm day-1 averaged globally, offsetting 64% of the wet scavenging induced decrease between polluted and clean conditions, defined according to percentiles of AOD. These demonstrate that wind speed is one of the major drivers of R-AOD relationships. Relative humidity at 915 hPa can also result in the positive relationships; however, its role is smaller than that of wind speed.