远海悬空波导陷获层底的位置通常与边界层浅云的云顶有很好的对应,气溶胶与边界层浅云的相互作用及其产生的辐射强迫将改变悬空波导的结构.文中利用天气预报-化学(weather research and forecasting-chemistry,WRF-Chem)模式通过设计不...远海悬空波导陷获层底的位置通常与边界层浅云的云顶有很好的对应,气溶胶与边界层浅云的相互作用及其产生的辐射强迫将改变悬空波导的结构.文中利用天气预报-化学(weather research and forecasting-chemistry,WRF-Chem)模式通过设计不包含完整气溶胶-云-辐射的EXP0试验(相当于WRF模式)和包含完整气溶胶-云-辐射相互作用(即气溶胶直接和间接效应)的EXP1试验,对2016年5月观测到的一次珍贵的远海高压型超强悬空波导过程进行了模拟分析.结果表明:远海高压天气形势下,EXP1试验模拟的由气溶胶活化后形成的云滴数浓度比EXP0试验云滴数浓度预设常值(100个cm-3)偏低;当伴随边界层浅云出现时,EXP1试验模拟的波导顶高和强度较EXP0试验更接近于实测;夜间进行的3次观测位于高压中心附近的无云区,此时气溶胶的直接和间接效应均可忽略,因此两组试验模拟的差异极小.这一结果从侧面说明,在有边界层浅云出现的远海区域,包含完整气溶胶-云-辐射效应的WRF-Chem模式有利于提高悬空波导特征量的模拟效果.展开更多
Enhancing the ability of the WRF model in simulating a large area covering the West Pacific Ocean, China's Mainland, and the East Indian Ocean is very important to improve prediction of the East Asian monsoon clim...Enhancing the ability of the WRF model in simulating a large area covering the West Pacific Ocean, China's Mainland, and the East Indian Ocean is very important to improve prediction of the East Asian monsoon climate. The objective of this study is to identify a reasonable configuration of physical parameterization schemes to simulate the precipitation and temperature in this large area. The Mellor-Yamada-Janjic （MYJ） and Yonsei University （YSU） PBL schemes, the WSM3 and WSM5 microphysics schemes, and the Betts-Miller-Janjic （BMJ） and Tiedtke cumulus schemes are compared through simulation of the regional climate of summer 2008. All cases exhibit a similar spatial distribution of temperature as observed, and the spatial correlation coefficients are all higher than 0.95. The cases combining MY J, WSM3/WSM5, and BMJ have the smallest biases of temperature. The choice of PBL scheme has a significant effect on precipitation in such a large area. The cases with MYJ reproduce a better distribution of rain belts, while YSU strongly overestimates the precipitation intensity. The precipitation simulated using WSM3 is similar to that using WSM5. The BMJ cumulus scheme combined with the MYJ PBL scheme has a smaller bias of precipitation. However, the Tiedtke scheme reproduces the precipitation pattern better, especially over the ITCZ.展开更多
Techniques of rotating-disk and catalyst were used in investigating the kinetics of dolomite dissolution in flowing CO2-H2O system. Experiments run in the solutions equilibrated with various CO2 partial pressures (PCO...Techniques of rotating-disk and catalyst were used in investigating the kinetics of dolomite dissolution in flowing CO2-H2O system. Experiments run in the solutions equilibrated with various CO2 partial pressures (PCO2) from 30 to 100000 Pa. It shows that dissolution rates ofdolomite are related with rotating speeds at conditions far from equilibrium. This was explained by modified diffusion boundary layer (DBL) model. In addition, the dissolution rates increase after addition of carbonic anhydrase (CA) to solutions, where the CA catalyzes CO2 conversion. However, great differences occur among various CO2 partial pressures. The experimental observations give a conclusion that the modified DBL model enables one to predict dissolution rates and their behaviour at various PCO2 with satisfactory precision at least far from equilibrium.展开更多
Biases in shortwave cloud radiative forcing(SWCF), which cause overestimates in tropical regions and underestimates in subtropical marine stratocumulus regions, are common in many climate models. Here, two boundary la...Biases in shortwave cloud radiative forcing(SWCF), which cause overestimates in tropical regions and underestimates in subtropical marine stratocumulus regions, are common in many climate models. Here, two boundary layer processes are investigated in the atmospheric model GAMIL2, entrainment at the top of the boundary layer and longwave radiative cooling at the top of stratocumulus clouds, in order to reduce biases and reveal the mechanisms underlying these processes. Our results show that including the entrainment process in the model can reduce negative SWCF biases in most tropical regions but increases positive SWCF biases in subtropical marine stratocumulus regions. This occurs because entrainment reduces the low-level cloud fraction and its cloud liquid water content by suppressing the vertical turbulent diffusion in the boundary layer and decreasing the relative humidity when warm and dry free atmosphere is entrained in the boundary layer. Longwave radiative cooling at the top of stratocumulus clouds can enhance turbulent diffusion within the stratocumulus-topped boundary layer. When combined with the entrainment process, longwave radiative cooling reduces the positive SWCF biases in subtropical marine stratocumulus regions that are observed using the entrainment process alone. The incorporation of these two boundary layer processes improves the simulated SWCF in tropical and subtropical regions in GAMIL2.展开更多
文摘远海悬空波导陷获层底的位置通常与边界层浅云的云顶有很好的对应,气溶胶与边界层浅云的相互作用及其产生的辐射强迫将改变悬空波导的结构.文中利用天气预报-化学(weather research and forecasting-chemistry,WRF-Chem)模式通过设计不包含完整气溶胶-云-辐射的EXP0试验(相当于WRF模式)和包含完整气溶胶-云-辐射相互作用(即气溶胶直接和间接效应)的EXP1试验,对2016年5月观测到的一次珍贵的远海高压型超强悬空波导过程进行了模拟分析.结果表明:远海高压天气形势下,EXP1试验模拟的由气溶胶活化后形成的云滴数浓度比EXP0试验云滴数浓度预设常值(100个cm-3)偏低;当伴随边界层浅云出现时,EXP1试验模拟的波导顶高和强度较EXP0试验更接近于实测;夜间进行的3次观测位于高压中心附近的无云区,此时气溶胶的直接和间接效应均可忽略,因此两组试验模拟的差异极小.这一结果从侧面说明,在有边界层浅云出现的远海区域,包含完整气溶胶-云-辐射效应的WRF-Chem模式有利于提高悬空波导特征量的模拟效果.
基金funded by the National Natural Science Foundation of China[General Project,grant number 41275108]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA11010404]
文摘Enhancing the ability of the WRF model in simulating a large area covering the West Pacific Ocean, China's Mainland, and the East Indian Ocean is very important to improve prediction of the East Asian monsoon climate. The objective of this study is to identify a reasonable configuration of physical parameterization schemes to simulate the precipitation and temperature in this large area. The Mellor-Yamada-Janjic （MYJ） and Yonsei University （YSU） PBL schemes, the WSM3 and WSM5 microphysics schemes, and the Betts-Miller-Janjic （BMJ） and Tiedtke cumulus schemes are compared through simulation of the regional climate of summer 2008. All cases exhibit a similar spatial distribution of temperature as observed, and the spatial correlation coefficients are all higher than 0.95. The cases combining MY J, WSM3/WSM5, and BMJ have the smallest biases of temperature. The choice of PBL scheme has a significant effect on precipitation in such a large area. The cases with MYJ reproduce a better distribution of rain belts, while YSU strongly overestimates the precipitation intensity. The precipitation simulated using WSM3 is similar to that using WSM5. The BMJ cumulus scheme combined with the MYJ PBL scheme has a smaller bias of precipitation. However, the Tiedtke scheme reproduces the precipitation pattern better, especially over the ITCZ.
基金the National Natural Science Foundation of China (Grant No.40073026), the Ministry of Land and Resources of China (Grant No. 9806), the Ministry of Science and Technology of China (Special Research Project for Social Commonweal) (Grant No. 164), the Na
文摘Techniques of rotating-disk and catalyst were used in investigating the kinetics of dolomite dissolution in flowing CO2-H2O system. Experiments run in the solutions equilibrated with various CO2 partial pressures (PCO2) from 30 to 100000 Pa. It shows that dissolution rates ofdolomite are related with rotating speeds at conditions far from equilibrium. This was explained by modified diffusion boundary layer (DBL) model. In addition, the dissolution rates increase after addition of carbonic anhydrase (CA) to solutions, where the CA catalyzes CO2 conversion. However, great differences occur among various CO2 partial pressures. The experimental observations give a conclusion that the modified DBL model enables one to predict dissolution rates and their behaviour at various PCO2 with satisfactory precision at least far from equilibrium.
基金supported by the CAS Strategic Priority Research Program (Grant No. XDA05110304)the National Basic Research Program of China (Grant No. 2015CB954102)the National Natural Science Foundation of China (Grant Nos. 41205079 & 41305040)
文摘Biases in shortwave cloud radiative forcing(SWCF), which cause overestimates in tropical regions and underestimates in subtropical marine stratocumulus regions, are common in many climate models. Here, two boundary layer processes are investigated in the atmospheric model GAMIL2, entrainment at the top of the boundary layer and longwave radiative cooling at the top of stratocumulus clouds, in order to reduce biases and reveal the mechanisms underlying these processes. Our results show that including the entrainment process in the model can reduce negative SWCF biases in most tropical regions but increases positive SWCF biases in subtropical marine stratocumulus regions. This occurs because entrainment reduces the low-level cloud fraction and its cloud liquid water content by suppressing the vertical turbulent diffusion in the boundary layer and decreasing the relative humidity when warm and dry free atmosphere is entrained in the boundary layer. Longwave radiative cooling at the top of stratocumulus clouds can enhance turbulent diffusion within the stratocumulus-topped boundary layer. When combined with the entrainment process, longwave radiative cooling reduces the positive SWCF biases in subtropical marine stratocumulus regions that are observed using the entrainment process alone. The incorporation of these two boundary layer processes improves the simulated SWCF in tropical and subtropical regions in GAMIL2.
