Version 3.9 of WRF-ARW is run with a tropical belt configuration for a period from 2012 to 2016 in this study. The domain covers the entire tropics between 45°S and 45°N with a spatial resolution of about 45...Version 3.9 of WRF-ARW is run with a tropical belt configuration for a period from 2012 to 2016 in this study. The domain covers the entire tropics between 45°S and 45°N with a spatial resolution of about 45 km. In order to verify two radiation schemes and four cumulus convection schemes, eight experiments are performed with different combinations of physics parameterization schemes. The results show that eight experiments present reasonable spatial patterns of surface air temperature and precipitation in boreal summer, with the spatial correlation coefficient (COR) between simulated and observed temperature exceeding 0.95, and that between simulated and observed precipitation ranges from 0.65 to 0.82. The four experiments with the RRTMG radiation scheme show a better performance than the other four experiments with the CAM radiation scheme. In the four experiments with the RRTMG radiation scheme, the COR between simulated and observed surface air temperature is about 0.98, and that between simulated and observed precipitation ranges from 0.76 to 0.82. Comparatively, the two experiments using the new Tiedtke cumulus parameterization scheme can simulate better diurnal variation of precipitation in boreal summer than the other six experiments. In particular, for the diurnal cycle of precipitation over land and ocean, the experiment using the RRTMG radiation scheme and the new Tiedtke cumulus convection scheme shows that the peaks of precipitation rate appear at 0400 LST and 1600 LST, in agreement with observation.展开更多
The CME’s structure of solar wind(interplanetary magnetic field)is different from CIR’s.The two processes in which plasma and solar wind energy are injected into the Earth’s inner magnetosphere are not the same.So,...The CME’s structure of solar wind(interplanetary magnetic field)is different from CIR’s.The two processes in which plasma and solar wind energy are injected into the Earth’s inner magnetosphere are not the same.So,the variations of energetic elec- trons flux in the radiation belts are different between the storms associated with CMEs and CIRs.By using data from SAMPEX(Solar,Anomalous,and Magnetospheric Particle Explorer)satellite,we have investigated the dynamic variations of the outer radiation belt for 1.5–6.0 MeV electrons during 54 CME-driven storms and 26 CIR-driven recurrent storms.According to the superposed epoch analysis,for CME-and CIR-driven storms,when the Dst index reaches the minimum,the locations of the outer boundary move to L=4 and L=5.5,respectively.In the recovery phases,the locations of the outer boundary of the outer radiation belt are generally lower than and slightly higher than those before CME-and CIR-driven storms,respectively.We have found that the logarithmically decaying 1/e cut-off L-shell is a satisfying indicator of the outer boundary of the outer radiation belt.Furthermore,our study shows that the logarithmically decaying 1/e cut-off latitude is dependent on the Kp index in the main phases of CME-and CIR-driven storms,while in the recovery phases,there is no obvious correlation.In ad- dition,it has been shown that the locations of the peak electron flux are controlled by the minimum Dst index in the main phases of CME-driven storms.The influences of multiple storms on the electron flux of outer radiation belt have also been in- vestigated.展开更多
The subtropical mixed broad-leaved and coniferous forest, a typical successional monsoon forest, is one of the major forests in the subtropics of China. Therefore, it is very important to estimate the fluxes of the gr...The subtropical mixed broad-leaved and coniferous forest, a typical successional monsoon forest, is one of the major forests in the subtropics of China. Therefore, it is very important to estimate the fluxes of the greenhouse gases from the forest soil in order to evaluate the impact of subtropical forests on the greenhouse gas emissions or absorptions. This study investigated the diurnal variations of fluxes of three greenhouse gases （CO 2 , CH 4 , and N 2 O） from a mixed broad-leaved and coniferous forest soil. A static chamber-gas chromatograph technique was used to measure the fluxes of three greenhouse gases. By using the improved gas chromatography sampling system, the fluxes were analyzed with a single injection. In order to find out the effects of litter and seedling on the emissions or absorptions of these greenhouse gases, three treatments were set in the field:（1）bare soil surface （litter was removed previously）; （3） litter + soil; （3） seedling + litter + soil. The experimental results demonstrated that the forest soil was a source of CO 2 , N 2 O and a weak sink of CH 4 .The daily fluxes of CO 2 , CH 4 , and N 2 O from the soil surface were in the range of 488.99700.57, 0.0490.108 and –0.025 –0.053 mg/（m 2 ·h ）, respectively. CO 2 from the litter decomposition accounted for about 1/3 of the total CO 2 emission from the soil surface, while the litter and seedling had no significant effect on the fluxes of CH 4 and N 2 O. The fluxes of CO 2 and N 2 O measured at 9:00 11:00 a.m. were significantly different from their daily averages. Therefore, caution must be taken if the CO 2 and N 2 O fluxes measured within 9:0011:00 a.m. are used for extrapolation.展开更多
基金supported by the National Key Research Program of China [grant number 2016YFB0200805)the National Natural Science Foundation of China [grant number 41575089]
文摘Version 3.9 of WRF-ARW is run with a tropical belt configuration for a period from 2012 to 2016 in this study. The domain covers the entire tropics between 45°S and 45°N with a spatial resolution of about 45 km. In order to verify two radiation schemes and four cumulus convection schemes, eight experiments are performed with different combinations of physics parameterization schemes. The results show that eight experiments present reasonable spatial patterns of surface air temperature and precipitation in boreal summer, with the spatial correlation coefficient (COR) between simulated and observed temperature exceeding 0.95, and that between simulated and observed precipitation ranges from 0.65 to 0.82. The four experiments with the RRTMG radiation scheme show a better performance than the other four experiments with the CAM radiation scheme. In the four experiments with the RRTMG radiation scheme, the COR between simulated and observed surface air temperature is about 0.98, and that between simulated and observed precipitation ranges from 0.76 to 0.82. Comparatively, the two experiments using the new Tiedtke cumulus parameterization scheme can simulate better diurnal variation of precipitation in boreal summer than the other six experiments. In particular, for the diurnal cycle of precipitation over land and ocean, the experiment using the RRTMG radiation scheme and the new Tiedtke cumulus convection scheme shows that the peaks of precipitation rate appear at 0400 LST and 1600 LST, in agreement with observation.
基金supported by the National Natural Science Foundation of China(Grant Nos.40831061,41074117)the Specialized Research Fund for State Key Laboratories
文摘The CME’s structure of solar wind(interplanetary magnetic field)is different from CIR’s.The two processes in which plasma and solar wind energy are injected into the Earth’s inner magnetosphere are not the same.So,the variations of energetic elec- trons flux in the radiation belts are different between the storms associated with CMEs and CIRs.By using data from SAMPEX(Solar,Anomalous,and Magnetospheric Particle Explorer)satellite,we have investigated the dynamic variations of the outer radiation belt for 1.5–6.0 MeV electrons during 54 CME-driven storms and 26 CIR-driven recurrent storms.According to the superposed epoch analysis,for CME-and CIR-driven storms,when the Dst index reaches the minimum,the locations of the outer boundary move to L=4 and L=5.5,respectively.In the recovery phases,the locations of the outer boundary of the outer radiation belt are generally lower than and slightly higher than those before CME-and CIR-driven storms,respectively.We have found that the logarithmically decaying 1/e cut-off L-shell is a satisfying indicator of the outer boundary of the outer radiation belt.Furthermore,our study shows that the logarithmically decaying 1/e cut-off latitude is dependent on the Kp index in the main phases of CME-and CIR-driven storms,while in the recovery phases,there is no obvious correlation.In ad- dition,it has been shown that the locations of the peak electron flux are controlled by the minimum Dst index in the main phases of CME-driven storms.The influences of multiple storms on the electron flux of outer radiation belt have also been in- vestigated.
基金Supported by the Knowledge Innovation Funds from the Chinese Academy of Sciences(KZCX1-SW-01, KSCX2-SW-120)
文摘The subtropical mixed broad-leaved and coniferous forest, a typical successional monsoon forest, is one of the major forests in the subtropics of China. Therefore, it is very important to estimate the fluxes of the greenhouse gases from the forest soil in order to evaluate the impact of subtropical forests on the greenhouse gas emissions or absorptions. This study investigated the diurnal variations of fluxes of three greenhouse gases （CO 2 , CH 4 , and N 2 O） from a mixed broad-leaved and coniferous forest soil. A static chamber-gas chromatograph technique was used to measure the fluxes of three greenhouse gases. By using the improved gas chromatography sampling system, the fluxes were analyzed with a single injection. In order to find out the effects of litter and seedling on the emissions or absorptions of these greenhouse gases, three treatments were set in the field:（1）bare soil surface （litter was removed previously）; （3） litter + soil; （3） seedling + litter + soil. The experimental results demonstrated that the forest soil was a source of CO 2 , N 2 O and a weak sink of CH 4 .The daily fluxes of CO 2 , CH 4 , and N 2 O from the soil surface were in the range of 488.99700.57, 0.0490.108 and –0.025 –0.053 mg/（m 2 ·h ）, respectively. CO 2 from the litter decomposition accounted for about 1/3 of the total CO 2 emission from the soil surface, while the litter and seedling had no significant effect on the fluxes of CH 4 and N 2 O. The fluxes of CO 2 and N 2 O measured at 9:00 11:00 a.m. were significantly different from their daily averages. Therefore, caution must be taken if the CO 2 and N 2 O fluxes measured within 9:0011:00 a.m. are used for extrapolation.
