The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) plays an important role in regulating NOx. The N2O5 uptake coefficient, c(N2O5), was determined using an iterative box model that was constrained to observational data obtained in suburban Beijing from February to March 2016. The box model determined 2289 individual c(N2O5) values that varied from <0.001 to 0.02 with an average value of 0.0046 +/- 0.0039 (and a median value of 0.0032). We found the derived winter c(N2O5) values in Beijing were relatively low as compared to values reported in previous field studies conducted during winter in Hong Kong (average value of 0.014) and the eastern U.S. coast (median value of 0.0143). In our study, field evidence of the suppression of c(N2O5) values due to pNO3 content, organics and the enhancement by aerosol liquid water content (ALWC) is in line with previous laboratory study results. Low ALWC, high pNO3 content, and particle morphology (inorganic core with an organic shell) accounted for the low c (N2O5) values in the North China Plain (NCP) during wintertime. The field-derived c(N2O5) values are well reproduced by a revised parameterization method, which includes the aerosol size distribution, ALWC, nitrate and organic coating, suggesting the feasibility of comprehensive parameterization in the NCP during wintertime. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.
The diversity of vascular plants in Inner Asia has been researched; the main environmental factors determining the distribution of species belonging to various life forms and having different distribution range sizes have been identified. The key factors determining species diversity in Inner Asia are past climate changes and precipitation parameters. By contrast, the temperature conditions of the current climate do not affect the species richness significantly. The following current climatic parameters are important for woody plants: precipitation seasonality, mean precipitation in winter and spring, and diurnal range of temperature. Quite the opposite, the species richness of herbaceous plants is determined by climate-change velocity from the mid-Holocene and Last Glacial Maximum, the spatial heterogeneity of precipitation, and mean summer temperatures. Over time, distribution ranges of rare plants in the studied region may be reduced due to the increasing aridization.
Bilateral cross-currency SWAP agreements (BSAs) were rejuvenated during the GFC by the Federal Reserve of the United States to provide liquidity to selected governments in dire financial straits. After the crisis, BSAs rapidly and widely spread around the globe and become a major component of the global financial safety net. Interestingly, it is not the United States but China which occupies the center of the global BSA network. China has signed BSAs with a diverse pool of states since 2009, and has far more partners than any other countries. While existing studies mainly focus on the motivations driving China and its partner states to enter BSAs, this paper is intended to evaluate foreign policy consequences of China’s BSAs. Asymmetric interdependence and asymmetric information, as two key features of the economic relationship between China and its partner states in BSAs, are expected to make other countries be more supportive to China’s position in global affairs, leading to a convergence of their foreign policy preferences. This is the classic “Hirschman effect”.
To empirically identify the “Hirschman effect”, we use measures of states’ foreign policy ideal points based on votes in the United States General Assembly. We apply a quantitative analysis to estimate the average effect and conduct a case study to trace and explain the development of the effect over time. In the large-N study, we draw data on 191 countries between 2009 and 2018 and specify a multilevel model with varying intercepts to control for unobserved heterogeneity in the dimension of time and space. Empirical evidence suggests that BSAs significantly drive the foreign policy preferences of China and other states to converge. Then we focus on Argentina as an in-depth case study. Different from conventional case studies, we conduct a “quantitative case study” and apply the Synthetic Control Method to estimate and quantify the causal effect of signing a BSA with China in 2009 on the distance between foreign policy ideal points of Argentina and China. The case study confirms the presence of the “Hirschman effect” suggested by theory and found in the regression analysis. It further reveals several suggestive but interesting points, including 1) activating SWAP lines may strengthen the effect, whereas the effect may be weakened by the provision of emergency liquidity assistance from the US or the IMF; 2) BSAs with China may impact on left-wing governments more strongly than right-wing governments; and 3) the Chinese government may strengthen the effect by changing the size of the committed SWAP line.