Marine biogenic aerosols and their effects on aerosol-cloud interactions over the Southern Ocean:a review

The Southern Ocean(SO)plays an important role in the global climate system.Changes in SO biogeochemistry and marine ecosystems may influence the distribution of atmospheric aerosols and clouds and impact the climate system.We reviewed current knowledge on the interactions between marine aerosols and clouds over the SO.We focused on marine primary and secondary organic aerosols and summarized their characteristics,processes and roles as cloud condensation nuclei and ice nuclei.We described in detail the interactions between the marine ecosystem,aerosols and clouds.We discussed marine productivity,formation of marine biogenic aerosols and interactions between aerosols,clouds and climate.We explored the impact of climate change on SO marine ecosystem productivity and aerosol-cloud-climate feedback.Marine biogenic aerosols could impact the radiation budget and oceanic low-level clouds over the SO.This study contributes towards an improved understanding of marine productivity,aerosol-cloud interactions and climate change in the SO.The SO may respond to climate change in varying degrees.More studies are urgently needed to support accurate forecasts of future changes in the SO.

Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured using gas chromatography/mass spectrometry （GC/MS）. Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations （R^2 = 0.44-0.90） between BSOA and sulfate were found at the six sites, suggesting that anthropogenic pollution （i.e., sulfate） could enhance SOA formation, because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode （〈3.3 μm） except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse （〉3.3 μm） modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.