The background surface O3 concentrations and seasonal changes observed at the Zhongshan Station (69°22'2''S, 76°21'49''E;18.5 m), east Antarctica from 2008 to 2013 are presented. Irre...The background surface O3 concentrations and seasonal changes observed at the Zhongshan Station (69°22'2''S, 76°21'49''E;18.5 m), east Antarctica from 2008 to 2013 are presented. Irrespective of wind direction, surface O3 concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1.1% of the data. These O3 exhibit the expected lowest in summer, with a peak in winter. The daily range of average O3 in all four seasons is small. The monthly mean O3 is similar to that of other stations in Antarctica, with seasonal CO2 amplitudes in the order of 15 ppb to 35 ppb. Surface O3 significantly negatively correlated with UVB in the spring and autumn, with correlation coefficients of 0.50 and 0.57 under the 0.01 significance test. Furthermore, the surface O3 concentration during polar nights was 1 - 2 times higher than that during polar days. Thus, the chemical effect of the aurora lights was the dominant cause of ozone destruction, showing that surface O3 observed in Antarctica has a small interferences from human activities in the atmosphere as it moves from the north through the southern hemisphere.展开更多
Background CH<sub>4</sub> concentration and seasonal variations measured at Zhongshan Station (69°22'2''S, 76°21'49''E, 18.5 m) in Antarctica from 2008 through 2013 are pr...Background CH<sub>4</sub> concentration and seasonal variations measured at Zhongshan Station (69°22'2''S, 76°21'49''E, 18.5 m) in Antarctica from 2008 through 2013 are presented and discussed. From 2008-2013 CH<sub>4</sub> was measured in weekly<sub> </sub>flask samples and started on line measurement by Picarro CO<sub>2</sub>/CH<sub>4</sub>/H<sub>2</sub>O analyzer from March, 2010-2013. These CH<sub>4</sub> measurements show the expected growth period of CH<sub>4</sub> concentration during February (Antarctic spring) with a peak in September (fall). Irrespective of wind direction, CH<sub>4</sub> concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1% of the data. The mean daily cycle of CH<sub>4</sub> concentration in all four seasons is small. The monthly mean CH<sub>4</sub> concentration at Zhongshan station is similar to those at other stations in Antarctica showing that CH<sub>4</sub> observed in Antarctica is fully mixed in the atmosphere as it is transported from the northern through the southern hemisphere. The annual CH<sub>4</sub> increase in recent years at Zhongshan station is 4.8 ppb·yr<sup>-1</sup>.展开更多
When the horizontal grid size of a numerical weather prediction(NWP)model is between a few hundred meters and~10 km,referred to as the gray zone,updrafts in convective clouds cannot be fully resolved explicitly and th...When the horizontal grid size of a numerical weather prediction(NWP)model is between a few hundred meters and~10 km,referred to as the gray zone,updrafts in convective clouds cannot be fully resolved explicitly and the use of a subgrid convective cloud parameterization scheme is still necessary.Since some critical assumptions in the mass-flux formulation of conventional subgrid convective cloud parameterization become invalid for gray-zone resolutions,it is required for a generalized parameterization to be developed to properly describe subgrid convective clouds.To meet this requirement,a new subgrid convective cloud parameterization scheme that is based on the mass-flux formulation and suitable for gray-zone resolutions has been proposed and preliminarily tested in the Weather Research and Forecasting(WRF)model.This new scheme is automatically adaptive to variation in grid size(i.e.,scale-aware),and accounts for microphysical processes consistently with grid-resolved clouds.Numerical experiment of an idealized tropical cyclone shows that this new scheme has a substantial impact on the tropical cyclone’s intensity and precipitation distribution due to the effect of subgrid clouds on the total diabatic heating.展开更多
文摘The background surface O3 concentrations and seasonal changes observed at the Zhongshan Station (69°22'2''S, 76°21'49''E;18.5 m), east Antarctica from 2008 to 2013 are presented. Irrespective of wind direction, surface O3 concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1.1% of the data. These O3 exhibit the expected lowest in summer, with a peak in winter. The daily range of average O3 in all four seasons is small. The monthly mean O3 is similar to that of other stations in Antarctica, with seasonal CO2 amplitudes in the order of 15 ppb to 35 ppb. Surface O3 significantly negatively correlated with UVB in the spring and autumn, with correlation coefficients of 0.50 and 0.57 under the 0.01 significance test. Furthermore, the surface O3 concentration during polar nights was 1 - 2 times higher than that during polar days. Thus, the chemical effect of the aurora lights was the dominant cause of ozone destruction, showing that surface O3 observed in Antarctica has a small interferences from human activities in the atmosphere as it moves from the north through the southern hemisphere.
文摘Background CH<sub>4</sub> concentration and seasonal variations measured at Zhongshan Station (69°22'2''S, 76°21'49''E, 18.5 m) in Antarctica from 2008 through 2013 are presented and discussed. From 2008-2013 CH<sub>4</sub> was measured in weekly<sub> </sub>flask samples and started on line measurement by Picarro CO<sub>2</sub>/CH<sub>4</sub>/H<sub>2</sub>O analyzer from March, 2010-2013. These CH<sub>4</sub> measurements show the expected growth period of CH<sub>4</sub> concentration during February (Antarctic spring) with a peak in September (fall). Irrespective of wind direction, CH<sub>4</sub> concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1% of the data. The mean daily cycle of CH<sub>4</sub> concentration in all four seasons is small. The monthly mean CH<sub>4</sub> concentration at Zhongshan station is similar to those at other stations in Antarctica showing that CH<sub>4</sub> observed in Antarctica is fully mixed in the atmosphere as it is transported from the northern through the southern hemisphere. The annual CH<sub>4</sub> increase in recent years at Zhongshan station is 4.8 ppb·yr<sup>-1</sup>.
基金supported by the Special Scientific Research Fund of Meteorological Public Welfare of China GYHY201206006the National Science Foundation of China Grants 41175094,41575101.
文摘When the horizontal grid size of a numerical weather prediction(NWP)model is between a few hundred meters and~10 km,referred to as the gray zone,updrafts in convective clouds cannot be fully resolved explicitly and the use of a subgrid convective cloud parameterization scheme is still necessary.Since some critical assumptions in the mass-flux formulation of conventional subgrid convective cloud parameterization become invalid for gray-zone resolutions,it is required for a generalized parameterization to be developed to properly describe subgrid convective clouds.To meet this requirement,a new subgrid convective cloud parameterization scheme that is based on the mass-flux formulation and suitable for gray-zone resolutions has been proposed and preliminarily tested in the Weather Research and Forecasting(WRF)model.This new scheme is automatically adaptive to variation in grid size(i.e.,scale-aware),and accounts for microphysical processes consistently with grid-resolved clouds.Numerical experiment of an idealized tropical cyclone shows that this new scheme has a substantial impact on the tropical cyclone’s intensity and precipitation distribution due to the effect of subgrid clouds on the total diabatic heating.
