In order to develop a seasonal snow model of land surface process as accurately as possible for climatic study. it is necessary to fully understand the effects of important snow internal processes and interaction with...In order to develop a seasonal snow model of land surface process as accurately as possible for climatic study. it is necessary to fully understand the effects of important snow internal processes and interaction with air and to get an insight into influence of several relevant parameterization schemes with parameters' uncertainty to some degree. Using the snow model (SAST) developed by first author and other one and some useful field observation data, this paper has conducted a series of sensitivity studies on the parameterization schemes. They are relative to compaction process, snow thermal conduction, methodology of layering snow pack and to key parameters such as snow albedo, water holding capacity. Then, based on the results from the sensitivity studies, some useful conclusions for snow cover model improvement are obtained from the analysis of the results.展开更多
Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM). Recently, the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmosph...Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM). Recently, the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP) has developed a new version of a GCM (R42L9). In this work, roles of cloud parameterization in the R42L9 are evaluated through a comparison between two 20-year simulations using different cloud schemes. One scheme is that the cloud in the model is diagnosed from relative humidity and vertical velocity, and the other one is that diagnostic cloud is replaced by retrieved cloud amount from the International Satellite Cloud Climatology Project (ISCCP), combined with the amounts of high-, middle-, and low-cloud and heights of the cloud base and top from the NCEP. The boreal winter and summer seasonal means, as well as the annual mean, of the simulated top-of-atmosphere shortwave radiative flux, surface energy fluxes, and precipitation are analyzed in comparison with the observational estimates and NCEP reanalysis data. The results show that the scheme of diagnostic cloud parameterization greatly contributes to model biases of radiative budget and precipitation. When our derived cloud fractions are used to replace the diagnostic cloud amount, the top-of-atmosphere and surface radiation fields are better estimated as well as the spatial pattern of precipitation. The simulations of the regional precipitation, especially over the equatorial Indian Ocean in winter and the Asia-western Pacific region in summer, are obviously improved.展开更多
This study discusses the sensitivity of convective parameterization schemes（CPSs） in the Regional Climate Model（version 4.3）（Reg CM4.3） over East/South Asia. The simulations using different CPSs in Reg CM are co...This study discusses the sensitivity of convective parameterization schemes（CPSs） in the Regional Climate Model（version 4.3）（Reg CM4.3） over East/South Asia. The simulations using different CPSs in Reg CM are compared to discover a suitable scheme for this region, as the performance of different schemes is greatly influenced by region and seasonality. Over Southeast China and the Bay of Bengal, the Grell scheme exhibits the lowest RMSEs of summer precipitation compared to observed data. Moreover, the Emanuel over land and Grell over ocean（ELGO） scheme enhances the simulation, in comparison with any single CPS（Grell/Emanuel） over Western Ghats, Sri Lanka, and Southeast India. Over the Huang–Huai–Hai Plain（3H） and Tibetan Plateau（TP） regions of China, the Tiedtke scheme simulates the more reasonable summer precipitation with high correlation coefficient and comparable amplitude. Especially, it reproduces a minimum convective precipitation bias of 8 mm d^-1and the lowest RMSEs throughout the year over East/South Asia. Furthermore, for seasonal variation of precipitation, the Tiedtke scheme results are closer to the observed data over the 3H and TP regions. However, none of the CPSs is able to simulate the seasonal variation over North Pakistan（NP）. In comparison with previous research, the results of this study support the Grell scheme over South Asia. However, the Tiedtke scheme shows superiority for the 3H, TP and NP regions. The thicker PBL, less surface latent heat flux, the unique ability of deep convection and the entrainment process in the Tiedtke scheme are responsible for reducing the wet bias.展开更多
Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agri...Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agriculture,a cloud model was applied to a water resource system using five sustainable water resource utilization schemes for Kiamusze,Heilongjiang Province,as an example.This research changes the qualitative description of the concept language into a quantitative analysis of an evaluation indicator.A cloud model-based analytical method for regional sustainable water resource utilization schemes was proposed,and the sustainable grades of the water resources were calculated.The research results showed that,in addition to the natural continuation of such schemes,the development trends of four new schemes achieved the sustainable utilization of water resources,and thus,the sustainable water resource utilization was optimized.However,when the open-source,throttle,comprehensive and coordination schemes were subjected to the optimum applicability analysis,based on the limiting factors in different periods,resource availability and long-term development,decision-making regarding the best solution in different periods better ensures sustainable development in Kiamusze.The research results provide a significant theoretical basis for the formulation of scientific and reasonable sustainable water resource utilization strategies in Kiamusze.展开更多
In this study, a statistical cloud scheme is first introduced and coupledwith a first-order turbulence scheme with second-order turbulence moments parameterized by thetimescale of the turbulence dissipation and the ve...In this study, a statistical cloud scheme is first introduced and coupledwith a first-order turbulence scheme with second-order turbulence moments parameterized by thetimescale of the turbulence dissipation and the vertical turbulent diffusion coefficient. Then theability of the scheme to simulate cloud fraction at different relative humidity, verticaltemperature profile, and the timescale of the turbulent dissipation is examined by numericalsimulation. It is found that the simulated cloud fraction is sensitive to the parameter used in thestatistical cloud scheme and the timescale of the turbulent dissipation. Based on the analyses, theintroduced statistical cloud scheme is modified. By combining the modified statistical cloud schemewith a boundary layer cumulus scheme, a new statistically-based low-level cloud scheme is proposedand tentatively applied in NCAR (National Center for Atmospheric Research) CCM3 (Community ClimateModel version 3). It is found that the simulation of low-level cloud fraction is markedly improvedand the centers with maximum low-level cloud fractions are well simulated in the cold oceans off thewestern coasts with the statistically-based low-level cloud scheme applied in CCM3. It suggeststhat the new statistically-based low-level cloud scheme has a great potential in the generalcirculation model for improving the low-level cloud parameterization.展开更多
基金This work is financially supported by 1) National Key Programme for Developing Basic Sciences.G1998040900-Part 1, 2) NSF (key
文摘In order to develop a seasonal snow model of land surface process as accurately as possible for climatic study. it is necessary to fully understand the effects of important snow internal processes and interaction with air and to get an insight into influence of several relevant parameterization schemes with parameters' uncertainty to some degree. Using the snow model (SAST) developed by first author and other one and some useful field observation data, this paper has conducted a series of sensitivity studies on the parameterization schemes. They are relative to compaction process, snow thermal conduction, methodology of layering snow pack and to key parameters such as snow albedo, water holding capacity. Then, based on the results from the sensitivity studies, some useful conclusions for snow cover model improvement are obtained from the analysis of the results.
文摘Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM). Recently, the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP) has developed a new version of a GCM (R42L9). In this work, roles of cloud parameterization in the R42L9 are evaluated through a comparison between two 20-year simulations using different cloud schemes. One scheme is that the cloud in the model is diagnosed from relative humidity and vertical velocity, and the other one is that diagnostic cloud is replaced by retrieved cloud amount from the International Satellite Cloud Climatology Project (ISCCP), combined with the amounts of high-, middle-, and low-cloud and heights of the cloud base and top from the NCEP. The boreal winter and summer seasonal means, as well as the annual mean, of the simulated top-of-atmosphere shortwave radiative flux, surface energy fluxes, and precipitation are analyzed in comparison with the observational estimates and NCEP reanalysis data. The results show that the scheme of diagnostic cloud parameterization greatly contributes to model biases of radiative budget and precipitation. When our derived cloud fractions are used to replace the diagnostic cloud amount, the top-of-atmosphere and surface radiation fields are better estimated as well as the spatial pattern of precipitation. The simulations of the regional precipitation, especially over the equatorial Indian Ocean in winter and the Asia-western Pacific region in summer, are obviously improved.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2EW-QN208)a project of the National Natural Science Foundation of China (Grant No. 41275082)+1 种基金the National Basic Research Program of China (Grant Nos. 2010CB428502 and 2011CB952003)the R&D Special Fund for Public Welfare Industry (meteorology) of the Ministry of Finance and the Ministry of Science and Technology (GYHY201006014-04)
文摘This study discusses the sensitivity of convective parameterization schemes（CPSs） in the Regional Climate Model（version 4.3）（Reg CM4.3） over East/South Asia. The simulations using different CPSs in Reg CM are compared to discover a suitable scheme for this region, as the performance of different schemes is greatly influenced by region and seasonality. Over Southeast China and the Bay of Bengal, the Grell scheme exhibits the lowest RMSEs of summer precipitation compared to observed data. Moreover, the Emanuel over land and Grell over ocean（ELGO） scheme enhances the simulation, in comparison with any single CPS（Grell/Emanuel） over Western Ghats, Sri Lanka, and Southeast India. Over the Huang–Huai–Hai Plain（3H） and Tibetan Plateau（TP） regions of China, the Tiedtke scheme simulates the more reasonable summer precipitation with high correlation coefficient and comparable amplitude. Especially, it reproduces a minimum convective precipitation bias of 8 mm d^-1and the lowest RMSEs throughout the year over East/South Asia. Furthermore, for seasonal variation of precipitation, the Tiedtke scheme results are closer to the observed data over the 3H and TP regions. However, none of the CPSs is able to simulate the seasonal variation over North Pakistan（NP）. In comparison with previous research, the results of this study support the Grell scheme over South Asia. However, the Tiedtke scheme shows superiority for the 3H, TP and NP regions. The thicker PBL, less surface latent heat flux, the unique ability of deep convection and the entrainment process in the Tiedtke scheme are responsible for reducing the wet bias.
基金The Natural Science Foundation of China(51279031,51479032,51679039 and 51579044)the Heilongjiang Province Water Conservancy Science and Technology project(201318 and 201503)+1 种基金the Heilongjiang Province Outstanding Youth Fund(JC201402)the Yangtze River Scholars Support Program of Colleges and Universities in Heilongjiang Province.
文摘Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agriculture,a cloud model was applied to a water resource system using five sustainable water resource utilization schemes for Kiamusze,Heilongjiang Province,as an example.This research changes the qualitative description of the concept language into a quantitative analysis of an evaluation indicator.A cloud model-based analytical method for regional sustainable water resource utilization schemes was proposed,and the sustainable grades of the water resources were calculated.The research results showed that,in addition to the natural continuation of such schemes,the development trends of four new schemes achieved the sustainable utilization of water resources,and thus,the sustainable water resource utilization was optimized.However,when the open-source,throttle,comprehensive and coordination schemes were subjected to the optimum applicability analysis,based on the limiting factors in different periods,resource availability and long-term development,decision-making regarding the best solution in different periods better ensures sustainable development in Kiamusze.The research results provide a significant theoretical basis for the formulation of scientific and reasonable sustainable water resource utilization strategies in Kiamusze.
基金This study is jointly supported by the Chinese Academy of Sciences "Innovation Program" under Grant ZKCX2-SW-210, theNational Natural Science Foundation of China under Grant Nos. 40233031, 40231004, and 40221503, and the National Key BasicResearch Projec
文摘In this study, a statistical cloud scheme is first introduced and coupledwith a first-order turbulence scheme with second-order turbulence moments parameterized by thetimescale of the turbulence dissipation and the vertical turbulent diffusion coefficient. Then theability of the scheme to simulate cloud fraction at different relative humidity, verticaltemperature profile, and the timescale of the turbulent dissipation is examined by numericalsimulation. It is found that the simulated cloud fraction is sensitive to the parameter used in thestatistical cloud scheme and the timescale of the turbulent dissipation. Based on the analyses, theintroduced statistical cloud scheme is modified. By combining the modified statistical cloud schemewith a boundary layer cumulus scheme, a new statistically-based low-level cloud scheme is proposedand tentatively applied in NCAR (National Center for Atmospheric Research) CCM3 (Community ClimateModel version 3). It is found that the simulation of low-level cloud fraction is markedly improvedand the centers with maximum low-level cloud fractions are well simulated in the cold oceans off thewestern coasts with the statistically-based low-level cloud scheme applied in CCM3. It suggeststhat the new statistically-based low-level cloud scheme has a great potential in the generalcirculation model for improving the low-level cloud parameterization.
