Precipitation response to aerosol–radiation and aerosol–cloud interactions in regional climate simulations over Europe

Abstract

Abstract. The effect of aerosols on regional climate simulations presents large uncertainties due to their complex and non-linear interactions with a wide variety of factors, including aerosol–radiation (ARI) and aerosol–cloud (ACI) interactions. These interactions are strongly conditioned by the meteorological situation and type of aerosol, but, despite their increase, only a limited number of studies have covered this topic from a regional and climatic perspective. This contribution thus aims to quantify the impacts on precipitation of the inclusion of ARI and ACI processes in regional climate simulations driven by ERA20C reanalysis. A series of regional climatic simulations (for the period 1991–2010) for the Euro-CORDEX domain were conducted including ARI and ARI + ACI (ARCI), establishing as a reference a simulation where aerosols were not included interactively (BASE). The results show that the effects of ARI and ACI on time-mean spatially averaged precipitation over the whole domain are limited. However, a spatial redistribution of precipitation occurs when the ARI and ACI processes are introduced into the model, as well do changes in the precipitation intensity regimes. The main differences with respect to the base-case simulations occur in central Europe, where a decrease in precipitation is associated with a depletion in the number of rainy days and clouds at low level (CLL). This reduction in precipitation presents a strong correlation with the ratio PM2.5∕PM10, since the decrease is especially intense during those events with high values of that ratio (pointing to high levels of anthropogenic aerosols) over central Europe. The precipitation decrease occurs for all ranges of precipitation rates. On the other hand, the model produces an increase in precipitation over the eastern Mediterranean basin associated with an increase in clouds and rainy days when ACIs are implemented. Here, the change is caused by the high presence of PM10 (low PM2.5∕PM10 ratios, pointing to natural aerosols). In this case, the higher amount of precipitation affects only days with low rates of precipitation. Finally, there are some disperse areas where the inclusion of aerosols leads to an increase in precipitation, especially for moderate and high precipitation rates.

Climate Change and Weather Extremes in the Eastern Mediterranean and Middle East

“…Scattering and absorption of solar radiation by atmospheric aerosols (such as dust and soot from the burning of biomass and pollution) can modify the radiation budget, atmospheric stability, heat fluxes and thus affect cloud formation, microphysics (albedo, droplet size distribution, and lifetime) and precipitation. In this respect, several studies focused on the indirect climate implications of aerosols and trace gases via their effect on cloud properties and convective precipitation processes over the EMME region (Bougiatioti et al, 2016;Kallos et al, 2014;López-Romero et al, 2021;Ramanathan et al, 2001;Rosenfeld et al, 2001;Solomos et al, 2011;Tang et al, 2018). On a global scale, desert dust exerts an estimated top of atmosphere (TOA) radiative forcing in the range of −0.6 to 0.4 Wm −2 , while in the EMME region, the forcing, both at the TOA and surface, is much more intense due to high surface reflectivity and enhanced aerosol loading, especially during the summer season (Alpert et al, 1998(Alpert et al, , 2005Alpert & Kishcha, 2008).…”

Sensitivity of surface solar radiation to aerosol–radiation and aerosol–cloud interactions over Europe in WRFv3.6.1 climatic runs with fully interactive aerosols

“…The concentration of sulfates was indirectly computed from the recorded concentrations of SO 2 and OH using the same kinetic reaction implemented in the RACM-KPP module. From the concentrations of the five aerosol species, the atmospheric optical depth (AOD) at 550 nm was estimated using the reconstructed mass extinction method (Malm et al, 1994), as in Palacios-Peña et al (2020). The RSDS and CCT data simulated by the driving GCM runs were used for comparison purposes.…”

Impact of Aerosols on NPP in Basins: Case Study of WRF−Solar in the Jinghe River Basin

“…The influence of aerosols on temperature and radiation changed gradually with latitude; however, the spatial distribution of rainfall changes showed a patchy pattern, with a certain degree of aggregation. This suggests that other environmental factors have synergistic effects on rainfall and aerosols [50]. Therefore, clouds and other environmental conditions should be considered when assessing rainfall.…”