The performance of a 100 m³ outdoor atmospheric simulation chamber in China

A new outdoor atmospheric simulation chamber with a volume of ∼100 m³, the largest one in Asia, was recently constructed in the Research Center for Eco-Environmental Sciences of the Chinese Academy of Sciences (Beijing, China). This Atmospheric Environment Simulation System (AESS-RCEES) is a hemispherical-shaped photoreactor constructed using sixteen stainless-steel brackets covered by double-layer Teflon film, offering two advantages over other outdoor chambers: 1) The AESS-RCEES effectively minimizes the "greenhouse effect" by continuously circulating cooling air through the double layer, resulting in mean temperature differences between the inside and outside of around 12 °C in winter and 9 °C in summer. 2) The chamber can quickly introduce ambient air through a special inlet system, completely replacing the air inside within 45 min. Using AESS-RCEES, the wall loss rates of various gaseous species and ambient particles have been investigated, it was observed that the loss rates of ambient particles were significantly slower than those of artificial (NH₄)₂SO₄ aerosol and secondary organic aerosol (SOA) formed by α-pinene ozonolysis. This suggests that the mixture of primary and SOA in the ambient air may have a longer lifetime than the aerosols generated individually. Investigation performed on propene/NOx photo-oxidation and α-pinene ozonolysis have shown that the AESS-RCEES is suitable for simulating atmospheric conditions and analyzing gas and particle chemical composition under controlled environmental conditions. This makes it a valuable platform for studying complex pollution and key chemical processes in the real atmosphere.