资源环境科技发展态势分析平台

This study addresses the analysis of the aerosol radiative forcing (ARF) and aerosol forcing efficiency (AFE) at surface in the Photosynthetically Active and Total radiation ranges in a Southwest Mediterranean site. A thorough analysis of a long-term database (2008–2018) has been performed, bringing very valuable results about both, the absolute values and trends in ARF and AFE for both spectral intervals. The largest monthly mean for aerosol optical depth at 500 nm (AOD₅₀₀) is found in summer (0.16 at July and August) meanwhile the lowest value is in winter (0.08 at November and December), with an interannual range varying from 0.11 ± 0.03 (in 2018) to 0.17 ± 0.03 (in 2014). The AFE variation range has been estimated between −12 and − 198 Wm⁻²τ⁻¹ for PAR and between −9 and − 450 Wm⁻²τ⁻¹ for Total irradiance. ARF varies between −1 Wm⁻² and -23 Wm⁻² in the PAR range, taking values from −1 to −40 Wm⁻² in the Total one. This result points out the relevance of the aerosol effects on the PAR range, which can involve up to a 50% of the Total ARF. Moreover, a notable dependence of ARF and AFE on the solar position has been detected, increasing their absolute values at solar zenith angle from 0^o to 45^o-60^o and decreasing to zero for lower solar positions. Additionally, this analysis has revealed the existence of a significant downward trend in AFE values for PAR, with a slope of 2.7 Wm⁻²τ⁻¹ year⁻¹. Although the slope is positive, taking into account that the AFE values are negative, the slope value implies that the aerosol cooling radiative effect of aerosols is decreasing. However, no trends have been detected neither in AFE nor ARF values in the Total solar range. These results evidence the long-term aerosol effects over the different spectral intervals and emphasize the need for detailed analysis of the aerosol radiative effects on fundamental spectral intervals such as the PAR range.