Séminaire M. Chin
NASA Goddard Space Flight Center, USA
Mercredi 29 mars 2017, 14:30, bibliothèque du LOA, Université de Lille Sciences et Technologies
Multidecadal variations of solar radiation reaching the surface – what is the role of aerosols ?
Incoming solar radiation drives the Earth’s climate system. Long-term surface observations of the solar radiation reaching the surface (RSFC) have shown decreasing or increasing trends, often referred to as solar “dimming” or “brightening”, in many regions of the world in the past several decades. Such long-term variation of RSFC mostly reflects the change of the solar-attenuation components within the atmosphere.
Anthropogenic emissions of aerosols and precursor gases have changed significantly in the past decades with increase or decrease mirroring the change in RSFC over many regions, leading to suggestions that aerosols may play a critical role in determining RSFC trends.
This work is to assess the role of direct radiative effects of aerosols on the solar “dimming” and “brightening” trends with modeling studies. First, we will show the trends of aerosol optical depth (AOD) and aerosol surface concentrations in different regions from 1980 to 2009 and attribute those changes to anthropogenic or natural sources. We will then use the GOCART model to attribute the “dimming/ brightening” trends to the changes of aerosols through the direct radiative effects. Finally, we will discuss the way forward to understand the aerosol effects on RSFC (as well as on other climate variables) through aerosol-cloud-radiation interactions.