D-region ion–neutral coupled chemistry (Sodankylä Ion Chemistry, SIC) within the Whole Atmosphere Community Climate Model (WACCM 4) – WACCM-SIC and WACCM-rSIC

This study presents a new ion–neutral chemical model coupled into the Whole Atmosphere Community Climate Model (WACCM). The ionospheric D-region (altitudes ∼  50–90 km) chemistry is based on the Sodankylä Ion Chemistry (SIC) model, a one-dimensional model containing 307 ion–neutral and ion recombination, 16 photodissociation and 7 photoionization reactions of neutral species, positive and negative ions, and electrons. The SIC mechanism was reduced using the simulation error minimization connectivity method (SEM-CM) to produce a reaction scheme of 181 ion–molecule reactions of 181 ion–molecule reactions of 27 positive and 18 negative ions. This scheme describes the concentration profiles at altitudes between 20 km and 120 km of a set of major neutral species (HNO3, O3, H2O2, NO, NO2, HO2, OH, N2O5) and ions (O2+, O4+, NO+, NO+(H2O), O2+(H2O), H+(H2O), H+(H2O)2, H+(H2O)3, H+(H2O)4, O3−, NO2−, O−, O2, OH−, O2−(H2O), O2−(H2O)2, O4−, CO3−, CO3−(H2O), CO4−, HCO3−, NO2−, NO3−, NO3−(H2O), NO3−(H2O)2, NO3−(HNO3), NO3−(HNO3)2, Cl−, ClO−), which agree with the full SIC mechanism within a 5 % tolerance. Four 3-D model simulations were then performed, using the impact of the January 2005 solar proton event (SPE) on D-region HOx and NOx chemistry as a test case of four different model versions: the standard WACCM (no negative ions and a very limited set of positive ions); WACCM-SIC (standard WACCM with the full SIC chemistry of positive and negative ions); WACCM-D (standard WACCM with a heuristic reduction of the SIC chemistry, recently used to examine HNO3 formation following an SPE); and WACCM-rSIC (standard WACCM with a reduction of SIC chemistry using the SEM-CM method). The standard WACCM misses the HNO3 enhancement during the SPE, while the full and reduced model versions predict significant NOx, HOx and HNO3 enhancements in the mesosphere during solar proton events. The SEM-CM reduction also identifies the important ion–molecule reactions that affect the partitioning of odd nitrogen (NOx), odd hydrogen (HOx) and O3 in the stratosphere and mesosphere

Short-Lived Trace Gases in the Surface Ocean and the Atmosphere

The two-way exchange of trace gases between the ocean and the atmosphere is important for both the chemistry and physics of the atmosphere and the biogeochemistry of the oceans, including the global cycling of elements. Here we review these exchanges and their importance for a range of gases whose lifetimes are generally short compared to the main greenhouse gases and which are, in most cases, more reactive than them. Gases considered include sulphur and related compounds, organohalogens, non-methane hydrocarbons, ozone, ammonia and related compounds, hydrogen and carbon monoxide. Finally, we stress the interactivity of the system, the importance of process understanding for modeling, the need for more extensive field measurements and their better seasonal coverage, the importance of inter-calibration exercises and finally the need to show the importance of air-sea exchanges for global cycling and how the field fits into the broader context of Earth System Science

Interprovincial migration, regional development and state policy in China, 1985-2010

Internal migration in China occurs as a result of both market forces and government interventions. This paper investigates how indicators of migration have changed over the past quarter of a century using data from successive censuses, with particular attention given to the roles of regional economic development and national policy and the effects of age and education on spatial patterns of migration. The results show a surge in migration throughout the period, an increasing concentration of migration destinations and an improvement of migration efficiency prior to 2000, but a decreased focusing of migration during the first decade of the twenty-first century. Widening regional disparity has been responsible for a sharp increase of migration from the interior to the coast, and different national economic growth poles emerged as major migration destinations at different stages of economic reforms. The analyses of age- and education-specific migration flows indicate that young adults were more mobile and more sensitive than older cohorts to interregional economic differentials, and that educated migrants were more concentrated than less-educated migrants since knowledge-based industries were more concentrated than labour-intensive industries. Our findings suggest that massive eastward migration induced by unbalanced economic development and relaxed migration restrictions still persisted in the 2000s, and that the State's recent efforts to alleviate regional inequalities were far from achieving equilibrium in the migration system

Les économies de l’UEMOA au regard de l’Observatoire de la compétitivité durable

Ferdi, Note brève B184L’Observatoire de la compétitivité durable retrace, pour l’Afrique, un tableau de bord ordonné autour de trois piliers thématiques : vulnérabilités, attractivité et compétitivité prix.La vulnérabilité physique aux changements climatiques est le facteur dominant pour le Sahel. Elle confère à l’UEMOA une moyenne des scores inférieure à celle de l’Afrique. Les vulnérabilités économiques structurelles et les violences sociétales sont en revanche moins accusées. Seuls la Côte d’Ivoire et le Sénégal se hissent à un niveau d’attractivité supérieur à celui de la moyenne africaine. En comparaison de l’Afrique, la compétitivité prix est légèrement plus favorable à l’Union. La Côte d’Ivoire fait bonne figure, mais également le Burkina Faso, le Mali et le Sénégal

Les francs CFA sont-ils à leur niveau d’équilibre ?

International audienceIn the Franc Zone, the fixed parity of the CFA franc is debated again, while the eco, a substitute currency, is to be announced in the WAEMU. We investigate the question about potential exchange rate misalignments in the two monetary unions (WAEMU, CEMAC) of this institutional space. The diagnosis is established by reference to two theories and from a panel of 99 countries over the period 1990-2016: the PPP exchange rate level adjusted for the productivity level and the Behavioural Equilibrium Exchange rate (BEER). These two theoretical criteria provide different results across unions, and country-members or sub-periods. Results are robust to the definition of the productivity measurement and to the sample size. Overall, the end of the period does not suggest misalignments that could justify a change of the parity although national heterogeneities arise.En Zone franc, la parité fixe des francs CFA fait de nouveau débat alors que l’éco, une monnaie de substitution, est annoncée en UEMOA. On s’interroge sur les mésalignements possibles du taux de change dans chacune des deux unions monétaires qui composent cet espace institutionnel de coopération (UEMOA, CEMAC). Le diagnostic est établi par référence à deux théories et un panel de 99 pays couvrant la période 1990-2016 : le taux de change de PPA ajusté de l’effet productivité et le taux de change d’équilibre comportemental (BEER). Ces deux critères donnent des résultats assez différents sur les unions entre les pays membres et sous-périodes considérées. Les résultats sont robustes aussi bien à la définition de la mesure de la productivité qu’à la taille de l’échantillon. Globalement, la fin de période ne suggère pas de mésalignements qui pourraient justifier un changement de parité avec cependant des hétérogénéités nationales

Les francs CFA sont-ils à leur niveau d’équilibre ?

International audienceIn the Franc Zone, the fixed parity of the CFA franc is debated again, while the eco, a substitute currency, is to be announced in the WAEMU. We investigate the question about potential exchange rate misalignments in the two monetary unions (WAEMU, CEMAC) of this institutional space. The diagnosis is established by reference to two theories and from a panel of 99 countries over the period 1990-2016: the PPP exchange rate level adjusted for the productivity level and the Behavioural Equilibrium Exchange rate (BEER). These two theoretical criteria provide different results across unions, and country-members or sub-periods. Results are robust to the definition of the productivity measurement and to the sample size. Overall, the end of the period does not suggest misalignments that could justify a change of the parity although national heterogeneities arise.En Zone franc, la parité fixe des francs CFA fait de nouveau débat alors que l’éco, une monnaie de substitution, est annoncée en UEMOA. On s’interroge sur les mésalignements possibles du taux de change dans chacune des deux unions monétaires qui composent cet espace institutionnel de coopération (UEMOA, CEMAC). Le diagnostic est établi par référence à deux théories et un panel de 99 pays couvrant la période 1990-2016 : le taux de change de PPA ajusté de l’effet productivité et le taux de change d’équilibre comportemental (BEER). Ces deux critères donnent des résultats assez différents sur les unions entre les pays membres et sous-périodes considérées. Les résultats sont robustes aussi bien à la définition de la mesure de la productivité qu’à la taille de l’échantillon. Globalement, la fin de période ne suggère pas de mésalignements qui pourraient justifier un changement de parité avec cependant des hétérogénéités nationales