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Relationships between the Limit of Predictability and Initial Error in the Uncoupled and Coupled Lorenz Models

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Advances in Atmospheric Sciences 2012年第5期29卷 1078-1088页

作者：丁瑞强李建平 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

In this study, the relationship between the limit of predictability and initial error was investigated using two simple chaotic systems： the Lorenz model, which possesses a single characteristic time scale, and the coupled Lorenz model, which possesses two different characteristic time scales. The limit of predictability is defined here as the time at which the error reaches 95% of its saturation level; nonlinear behaviors of the error growth are therefore involved in the definition of the limit of predictability. Our results show that the logarithmic function performs well in describing the relationship between the limit of predictability and initial error in both models, although the coefficients in the logarithmic function were not constant across the examined range of initial errors. Compared with the Lorenz model, in the coupled Lorenz model in which the slow dynamics and the fast dynamics interact with each other--there is a more complex relationship between the limit of predictability and initial error. The limit of predictability of the Lorenz model is unbounded as the initial error becomes infinitesimally small; therefore, the limit of predictability of the Lorenz model may be extended by reducing the amplitude of the initial error. In contrast, if there exists a fixed initial error in the fast dynamics of the coupled Lorenz model, the slow dynamics has an intrinsic finite limit of predictability that cannot be extended by reducing the amplitude of the initial error in the slow dynamics, and vice versa. The findings reported here reveal the possible existence of an intrinsic finite limit of predictability in a coupled system that possesses many scales of time or motion.

关键词： limit of predictability initial error Lorenz model coupled Lorenz model

The Significant Relationship between the Arctic Oscillation (AO) in December and the January Climate over South China

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Advances in Atmospheric Sciences 2011年第2期28卷 398-407页

作者：杨辉 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

Using NCEP/NCAR reanalysis data, the China rainfall and surface temperature data of the China Meteorological Administration, and the Arctic Oscillation （AO） indices of noaa, the author investigates relationships between the AO and the precipitation and temperature over China. There exists a good relationship between the AO index in December and the succeeding January precipitation over South China, indicating that when the December AO index is positive （negative）, the January precipitation over South China increases （decreases）. A remarkable negative correlation between the December AO index and the January surface temperature also exists over South China, indicating that when the December AO index is positive （negative）, the January temperature over South China drops （rises）. The occurrence of this anomalous climate is related to the anomalies of the atmospheric circulation systems. The December AO greatly influences circulation anomalies in January. A positive phase of the AO is found to lead to a stronger subtropical jet over the south side from the Iran Plateau to the Tibetan Plateau. Consequently, it results in a deepening pressure trough around the Bay of Bengal, which transports the warm and wet air to South China continuously. The Siberian High in January is stronger and extends farther southeastward. It results in continual cold air at 1000 hPa pouring into South China, inducing low temperature. Cooperating with the trough of the Bay of Bengal, anomalous precipitation occurs over South China. For the negative phase of the December AO, the opposite situation is observed.

关键词： Arctic Oscillation precipitation surface temperature large-scale circulation

Long-term Stability and Oceanic Mean State Simulated by the Coupled Model FGOALS-s2

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Advances in Atmospheric Sciences 2013年第1期30卷 175-192页

作者：林鹏飞俞永强刘海龙 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

We describe the long-term stability and mean climatology of oceanic circulations simulated by version 2 of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS-s2）. Driven by pre-industrial forcing, the integration of FGOALS-s2 was found to have remained stable, with no obvious climate drift over 600 model years. The linear trends of sea SST and sea surface salinity （SSS） were -0.04℃ （100 yr）-1 and 0.01 psu （100 yr）-1, respectively. The simulations of oceanic temperatures, wind-driven circulation and thermohaline circulation in FGOALS-s2 were found to be comparable with observations, and have been substantially improved over previous FGOALS-s versions （1.0 and 1.1）. However, significant SST biases （exceeding 3℃） were found around strong western boundary currents, in the East China Sea, the Sea of Japan and the Barents Sea. Along the eastern coasts in the Pacific and Atlantic Ocean, a warm bias （〉3℃） was mainly due to overestimation of net surface shortwave radiation and weak oceanic upwelling. The difference of SST biases in the North Atlantic and Pacific was partly due to the errors of meridional heat transport. For SSS, biases exceeding 1.5 psu were located in the Arctic Ocean and around the Gulf Stream. In the tropics, freshwater biases dominated and were mainly caused by the excess of precipitation. Regarding the vertical dimension, the maximal biases of temperature and salinity were located north of 65°N at depths of greater than 600 m, and their values exceeded 4℃ and 2 psu, respectively.

关键词： FGOALS stability mean state biases

Sensitivity of the Grid-point Atmospheric Model of IAP LASG(GAMILI.I.0)Climate Simulations to Cloud Droplet Effective Radius and Liquid Water Path

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Advances in Atmospheric Sciences 2008年第4期25卷 529-540页

作者：李立娟王斌周天军 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

This paper documents a study to examine the sensitivity to cloud droplet effective radius and liquid water path and the alleviation the energy imbalance at the top of the atmosphere and at the surface in the latest version of the Grid-point Atmospheric Model of the State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics （LASG）, Institute of Atmospheric Physics （IAP）（GAMIL1.1.0）. Considerable negative biases in all flux components, and thus an energy imbalance, are found in GAMIL1.1.0. In order to alleviate the energy imbalance, two modifications, namely an increase in cloud droplet effective radius and a decrease in cloud liquid water path, have been made to the cloud properties used in GAMIL. With the increased cloud droplet effective radius, the single scattering albedo of clouds is reduced, and thus the reflection of solar radiation into space by clouds is reduced and the net solar radiation flux at the top of the atmosphere is increased. With the reduced cloud optical depth, the net surface shortwave radiation flux is increased, causing a net warming over the land surface. This results in an increase in both sensible and latent heat fluxes over the land regions, which is largely balanced by the increased terrestrial radiation fluxes. Consequently, the energy balance at the top of atmosphere and at the surface is achieved with energy flux components consistent with available satellite observations.

关键词： GAMIL energy budget cloud droplet effective radius cloud liquid water path

Near Future (2016-40) Summer Precipitation Changes over China as Projected by a Regional Climate Model (RCM) under the RCP8.5 Emissions Scenario: Comparison between RCM Downscaling and the Driving GCM

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Advances in Atmospheric Sciences 2013年第3期30卷 806-818页

作者：邹立维周天军 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

Multi-decadal high resolution simulations over the CORDEX East Asia domain were performed with the regional climate model RegCM3 nested within the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 （FGOALS-g2）. Two sets of simulations were conducted at the resolution of 50 km, one for present day （1980-2005） and another for near-future climate （2015-40） under the Representative Concentration Pathways 8.5 （RCP8.5） scenario. Results show that RegCM3 adds value with respect to FGOALS-g2 in simulating the spatial patterns of summer total and extreme precipitation over China for present day climate. The major deficiency is that RegCM3 underestimates both total and extreme precipi- tation over the Yangtze River valley. The potential changes in total and extreme precipitation over China in summer under the RCP8.5 scenario were analyzed. Both RegCM3 and FGOALS-g2 results show that total and extreme precipitation tend to increase over northeastern China and the Tibetan Plateau, but tend to decrease over southeastern China. In both RegCM3 and FGOALS-g2, the change in extreme precipitation is weaker than that for total precipitation. RegCM3 projects much stronger amplitude of total and extreme precipitation changes and provides more regional-scale features than FGOALS-g2. A large uncertainty is found over the Yangtze River valley, where RegCM3 and FGOALS-g2 project opposite signs in terms of precipitation changes. The projected change of vertically integrated water vapor flux convergence generally follows the changes in total and extreme precipitation in both RegCM3 and FGOALS-g2, while the amplitude of change is stronger in RegCM3. Results suggest that the spatial pattern of projected precipitation changes may be more affected by the changes in water vapor flux convergence, rather than moisture content itself.

关键词： dynamical downscaling extreme precipitation near future precipitation changes

Development of a toy column model and its application in testing cumulus convection parameterizations

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Science Bulletin 2015年第15期60卷 1359-1365页

作者： Xiaocong Wang State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

A single-column model is constructed based on parameterizations inherited from the Finite-volume/Spectral Atmospheric Model F/SAMIL and tested in simulations of tropical convective systems. Two representative convection schemes are compared in terms of their performances on precipitation types, individual physical tendencies, and temperature and moisture fields. The main difference between the two selected schemes is in their representation of entraining/detraining process. The Tiedtke scheme assumes bulk entrainment, while the Zhang–Mc Farlane scheme parameterizes entrainment/detrainment rates under the spectrum concept. Large-scale forcing and verification data are taken from the GATE phase III field campaign, during which abundant convective events were observed. Given the same triggering function and closure assumption, results show that entrainment/detrainment representation remains the dominant factor on the simulation of cumulus mass flux and of temperature and moisture fields. By analyzing sources and sinks of heat and moisture, this study reveals how parameterization components compensate for each other and make model results insensitive to parameterization changes in certain fields, thus suggesting the need to treat parameterizations as systems rather than individual components.

关键词： Single-column model (SCM) TCM GATE Cumulus convection F/SAMIL

Progresses on two-phase modeling of proton exchange membrane water electrolyzer

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Energy Reviews 2024年第3期3卷 30-57页

作者： Boshi Xu Tao Ouyang Yang Wang Yang Yang Jun Li Liangliang Jiang Chaozhong Qin Dingding Ye Rong Chen Xun Zhu Qiang Liao Key laboratory of Low-grade Energy Utilization Technologies and Systems Ministry of EducationChongqing UniversityChongqing400030China Institute of Engineering Thermophysics School of Energy and Powering EngineeringChongqing UniversityChongqing400030China Department of Chemical and Petroleum Engineering The University of CalgaryCalgaryAlbertaCanada State Key laboratory of Coal Mine Disaster dynamics and Control Chongqing UniversityChongqing400044China

The Proton Exchange Membrane(PEM)water electrolyzer is considered one of the promising energy storing means for harnessing variable renewable energy sources to produce *** the internal fluid dynamics,which are often challenging to directly observe experimentally,has prompted the use of numerical models to investigate two-phase flow within PEM water *** this study,we provide a comprehensive review of prior research focusing on two-phase modeling of PEM electrolyzers,encompassing both components at mesoscopic scales and the full electrolyzer at the macroscopic *** delve into the specifics of various modeling approaches for two-phase flow at different scales and summarize and discuss the current state of the art in the ***,two-phase models for the full electrolyzer predominantly employ a macroscopic homogeneous ***,mesoscopic and microscopic models capable of tracking phase interfaces are limited to *** persist in integrating various modeling scales into a comprehensive electrolyzer model,particularly in coupling two-phase flow between the channels and porous *** efforts should focus on developing multi-scale models and simulating two-phase flow under fluctuating input ***,given the structural similarities between PEM water electrolyzers and PEM fuel cells,we compare and discuss differences in two-phase modeling between the two *** work offers the insights for researchers in the field of modeling of PEM water electrolyzers and even fuel cells.

关键词： Proton exchange membrane(PEM)water electrolyzer Two-phase model Multiscale modeling Water management Numerical simulation

Response of Sea Surface Temperature to Chlorophyll-a Concentration in the Tropical Pacific:Annual Mean,Seasonal Cycle,and Interannual Variability

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Advances in Atmospheric Sciences 2011年第3期28卷 492-510页

作者：林鹏飞刘海龙俞永强张学洪 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

The response of the upper-ocean temperatures and currents in the tropical Pacific to the spatial distribution of chlorophyll-a and its seasonal cycle is investigated using a coupled atmosphere-ocean model and a stand-alone oceanic general circulation *** spatial distribution of chlorophyll-a significantly influences the mean state of models in the tropical *** annual mean SST in the eastern equatorial Pacific decreases accompanied by a shallow thermocline and stronger currents because of shallow penetration depth of solar *** upwelling dominates the heat budget in that ***-ocean interaction processes can further amplify such changes. The seasonal cycle of chlorophyll-a can dramatically change ENSO period in the coupled *** introducing the seasonal cycle of chlorophyll-a concentration,the peak of the power spectrum becomes broad,and longer periods（3 years） are *** changes led to ENSO irregularities in the model. The increasing period is mainly due to the slow speed of Rossby waves,which are caused by the shallow mean thermocline in the northeastern Pacific.

关键词： chlorophyll-a concentration SST eastern equatorial Pacific ENSO

Asian Summer Monsoon Onset in Simulations and CMIP5 Projections Using Four Chinese Climate Models

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Advances in Atmospheric Sciences 2015年第6期32卷 794-806页

作者： ZOU Liwei ZHOU Tianjun State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

The reproducibility and future changes of the onset of the Asian summer monsoon were analyzed based on the simulations and projections under the Representative Concentration Pathways （RCP） scenario in which anthropogenic emissions continue to rise throughout the 21 st century （i.e. RCP8.5） by all realizations from four Chinese models that participated in the Coupled Model Intercomparison Project Phase 5 （CMIP5）. Delayed onset of the monsoon over the Arabian Sea was evident in all simulations for present-day climate, which was associated with a too weak simulation of the low-level Somali jet in May. A consistent advanced onset of the monsoon was found only over the Arabian Sea in the projections, where the advanced onset of the monsoon was accompanied by an increase of rainfall and an anomalous anticyclone over the northern Indian Ocean. In all the models except FGOALS-g2, the enhanced low-level Somali jet transported more water vapor to the Arabian Sea, whereas in FGOALS-g2 the enhanced rainfall was determined more by the increased wind convergence. Furthermore, and again in all models except FGOALS-g2, the equatorial SST warming, with maximum increase over the eastern Pacific, enhanced convection in the central West Pacific and reduced convection over the eastern Indian Ocean and Maritime Continent region, which drove the anomalous anticyclonic circulation over the western Indian Ocean. In contrast, in FGOALS-g2, there was minimal （near-zero） warming of projected SST in the central equatorial Pacific, with decreased convection in the central West Pacific and enhanced convection over the Maritime Continent. The broader-scale differences among the models across the Pacific were related to both the differences in the projected SST pattern and in the present-day simulations.

关键词： Asian summer monsoon onset climate projection Chinese climate models