徐永福课题组 - Prof. Yongfu Xu's Reasearch Group @ IAP CAS - Page 4

Global Air–Sea CO2 Flux in 22 CMIP5 Models: Multiyear Mean and Interannual Variability

Publish: January 17, 2017 Category: 最新消息 No Comments

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One standard deviation of the air–sea CO2 flux (10−9 kg m−2 s−1) among 18 models (the four models CMCC-CESM, INM-CM4.0, and GISS-E2-H/R-CC are excluded), based on the annual mean air–sea CO2 flux of the 18 models during 1996–2004. It indicates where models differ most in terms of air–sea CO2 flux.

To assess the capability of the latest Earth system models (ESMs) in representing historical global air–sea CO2 flux, 22 models from phase 5 of the Coupled Model Intercomparision Project (CMIP5) are analyzed, with a focus on the spatial distribution of multiyear mean and interannual variability. Results show that the global distribution of air–sea CO2 flux is reasonable in most of the models and that the main differences between models and observationally based results exist in regions with strong vertical movement. The annual mean flux in the 18-member multimodel ensemble (MME; four models were excluded because of their poor performances) mean during 1996–2004 is 1.95 PgC/yr (1 Pg = 1015 g; positive values mean into the ocean), and all but one model describe the rapid increasing trend of air–sea CO2 flux observed during 1960–2000. The first mode of the global air–sea CO2 flux variability during 1870–2000 in six of the models represents the El Niño–Southern Oscillation (ENSO) mode. The remaining 12 models fail to represent this important character for the following reasons: in five models, the tropical Pacific does not play a dominant role in the interannual variability of global air–sea CO2 flux because of stronger interannual variability in the Southern Ocean; two models poorly represent the interannual fluctuation of dissolved inorganic carbon (DIC) in the surface ocean of the tropical Pacific; and four models have shorter periods of the air–sea CO2 flux, which are out of the period range of ENSO events.

Dong F, Li Y, Wang B, et al. Global Air–Sea CO2Flux in 22 CMIP5 Models: Multiyear Mean and Interannual Variability[J]. Journal of Climate, 2016, 29(7): 2407-2431*
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Effect of particle water on ozone and SOA formation from benzene

Publish: June 12, 2016 Category: 最新消息 No Comments

Effect of particle water on ozone and secondary organic aerosol formation from benzene-NO2-NaCl irradiations
(颗粒水对苯光氧化生成臭氧和二次有机气溶胶的影响规律)

Highlights
Liquid water content (LWC) can affect the ability in forming O3 and SOA from benzene.
Heterogeneous reaction of N2O5 with H2O(aq) is the major reason for the decrease of O3.
Hydrates from glyoxal were the major contributors to SOA under high LWC conditions.
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Wang, Y.; Luo, H.; Jia, L.*; Ge, S. Effect of particle water on ozone and secondary organic aerosol formation from benzene-NO2-NaCl irradiations. Atmos. Environ. 2016, 140, 386–394.

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SOA formation from ethyne

Publish: February 14, 2016 Category: 最新消息 No Comments

High lightEthyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles.

FTIR spectra of SOA from ethyne
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The heterogeneous photochemical oxidation of ethyne was investigated under different relative humidity (RH) conditions in the presence of nitrogen oxides and sodium chloride in a self-made indoor smog chamber. The purpose was to study the influence of RH on the formation of secondary organic aerosol (SOA) from C2H2. Through the experiments, we found that SOA was rarely formed at <22% RH in the presence of NaCl seed particles, and that SOA began to be formed at ≥29 % RH in the presence of NaCl, which shows the importance of RH in the formation of SOA. The yield of SOA (YSOA) from C2H2 was 0.2 % at 51 % RH, and increased by a factor of 17.5 as RH reached 83%. The SOA yield increased with increasing RH. The geometric mean diameter of the particles increased by a factor of 1.17, 1.22, 1.28 and 1.51 at a RH of 51, 63, 74 and 83% respectively at the end of the experiment, indicating that the growth of the particle size also increased with increasing RH. Analysis of the SOA with Fourier-transform infrared (FTIR) spectrometry indicated that the particles generated from C2H2 contained the functional groups –OH, C=O, C–O–C and C–C–OH, for whose absorption peaks increase with increasing RH.

Ge Shuangshuang, Xu Yongfu, Jia Long (2016) Secondary organic aerosol formation from ethyne in the presence of NaCl in a smog chamber. Environmental Chemistry 13, 699-710.
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