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Decadal change of East Asian summer tropospheric temperature meridional gradient around the early 1990s

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Science China Earth Sciences 2015年第9期58卷 1609-1622页

作者： ZHANG LiXia zhou tianjun LASG Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Joint Center for Global Change Studies

During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper examines the decadal change of the East Asian summer tropospheric temperature around the early 1990 s. The results show that the meridional gradient of layer mean upper tropospheric temperature for 200–500 h Pa(here after UTT, UTT is upper tropospheric temperature) also underwent an obvious decadal decrease around 1992. The tropospheric temperature south to 35°N becomes decadal cooling, centered along the Yangtze River Valley, while the tropospheric temperature north to 35°N shows a decadal warming, centered in Northwest China-Mongolia. JRA-25 reanalysis is better than the other reanalysis datasets in revealing this decadal change. This decadal shift of East Asian summer UTT may be ascribed to the decadal change of the ENSO period from low-frequency oscillation(4–6 yr) to quasi-biennial oscillation since 1992. It behaves as an increase of ENSO developing events and a reduction of ENSO decaying events. It leads to stronger forcing of ENSO developing summer and weaker forcing of ENSO decaying summer, leading to the dominant role of monopole cooling mode of East Asian UTT after 1992, in contrast to the dominant role of dipole mode of East Asia UTT before 1992. The summer UTT difference between 1993–2004 and 1979–1992 shows a "South cooling-North Warming" pattern, and thereby contributes to the interdecadal decrease of East Asian summer UTT meridional gradient around 1992.

关键词： decadal variation around the early 1990s East Asian summer monsoon change of ENSO period

Uncertainty in crossing time of 2 °C warming threshold over China

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Science Bulletin 2016年第18期61卷 1451-1459页

作者： Xiaolong Chen tianjun zhou State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029 China

The 2 ℃ warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature （SAT） change over China will reach 2℃ rela- tive to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Repre- sentative Concentration Pathways （RCP4.5 and RCPS.5） from the Coupled Model Intercomparison Project Phase 5. The 2℃ threshold-crossing time （TCT） of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a 4-1o- range of inter- model SAT change, the upper and lower bounds of the 2 ℃ TCT could differ by about 25 years or even more. Uncer- tainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensi- tivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 ~C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a cli- mate more sensitive to CO2 forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radia- tion, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.

关键词： 2 °C threshold Projection uncertainty China region CMIP5 Climate sensitivity

Regional-scale Surface Air Temperature and East Asian Summer Monsoon Changes during the Last Millennium Simulated by the FGOALS-gl Climate System Model

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Advances in Atmospheric Sciences 2014年第4期31卷 765-778页

作者： MAN Wenmin zhou tianjun State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Climate Change Research Center Chinese Academy of Sciences

The spatial patterns and regional-scale surface air temperature （SAT） changes during the last millennium,as well as the variability of the East Asian summer monsoon （EASM） were simulated with a low-resolution version of Flexible Global Ocean-Atmosphere-Land-Sea-ice （FGOALS-gl） *** model was driven by both natural and anthropogenic forcing *** features of the simulated past millennial Northern Hemisphere （NH） mean SAT variations,including the Medieval Climate Anomaly （MCA）,the Little Ice Age （LIA） and the 20th Century Warming （20CW）,were generally consistent with the *** simulated MCA showed a global cooling pattern with reference to the 1961-90 mean conditions,indicating the 20CW to be unprecedented over the last millennium in the *** LIA was characterized by pronounced coldness over the continental extratropical NH in both the reconstruction and the *** simulated global mean SAT difference between the MCA and LIA was 0.14°C,with enhanced warming over high-latitude NH continental *** between the simulation and the reconstruction on regional scales were lower than those on hemispheric *** major features agreed well between the simulated and reconstructed SAT variations over the Chinese domain,despite some inconsistency in details among different *** EASM circulation during the MCA was stronger than that during the LIA The corresponding rainfall anomalies exhibited excessive rainfall in the north but deficient rainfall in the *** the zonal and meridional thermal contrast were enhanced during the *** temperature anomaly pattern favored a stronger monsoon circulation.

关键词： last millennium surface air temperature spatial patterns regional-scale variation East Asian summer monsoon

An Assessment of Improvements in Global Monsoon Precipitation Simulation in FGOALS-s2

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Advances in Atmospheric Sciences 2014年第1期31卷 165-178页

作者： ZHANG Lixia zhou tianjun State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

The performance of Version 2 of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS-s2） in simulat ing global monsoon precipitation （GMP） was evaluated. Compared with FGOALS-sl, higher skill in simulating the annual modes of climatological tropical precipitation and interannual variations of GMP are seen in FGOALS-s2. The simulated domains of the northwestern Pacific monsoon （NWPM） and North American monsoon are smaller than in FGOALS-s 1. The main deficiency of FGOALS-s2 is that the NWPM has a weaker monsoon mode and stronger negatiw,＇ pattern in spring-fall asymmetric mode. The smaller NWPM domain in FGOALS-s2 is due to its simulated colder SST over the western Pacific warm pool. The relationship between ENSO and GMP is simulated reasonably by FGOALS-s2. However, the simulated precipitation anomaly over the South African monsoon region-South Indian Ocean during La Nina years is opposite to the observation. This results mainly from weaker warm SST anomaly over the maritime continent during La Nifia years, leading to stronger upper-troposphere （lower-troposphere） divergence （convergence） over the Indian Ocean, and artificial vertical as cent （descent） over the Southwest Indian Ocean （South African monsoon region）, inducing local excessive （deficient） rainfall. Comparison between the historical and pre-industrial simulations indicated that global land monsoon precipitation changes from 1901 to the 1970s were caused by internal variation of climate system. External forcing may have contributed to the increasing trend of the Australian monsoon since the 1980s. Finally, it shows that global warming could enhance GMR especially over the northern hemispheric ocean monsoon and southern hemispheric land monsoon.

关键词： global monsoon precipitation climate model annual mode climate change

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

Development and evaluation of a regional ocean-atmosphere coupled model with focus on the western North Pacific summer monsoon simulation:Impacts of different atmospheric components

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Science China Earth Sciences 2012年第5期55卷 802-815页

作者： ZOU LiWei zhou tianjun LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

A regional ocean atmosphere coupled model (ROAM) is developed through coupler OASIS3,and is composed of regional climate model RegCM3 and CREM (Climate version of Regional Eta Model) as its atmospheric component and of a revised Princeton ocean model (POM2000) as its oceanic *** performance of the ROAM over the western North Pacific summer monsoon region is assessed by the case simulation of warm season in *** of different atmospheric model components on the performance of ROAM are *** with stand-alone simulation,CREM (RegCM3) produces more (or less) rainfall over ocean area with inclusion of the air-sea *** biases of rainfall are caused by the different biases of SST derived from the coupled *** (or cold) SST bias simulated by CREM_CPL (RegCM3_CPL) increases (or decreases) the evaporation at sea surface,then increases (or decreases) the rainfall over *** analyses suggest that the biases of vertical profile of temperature and specific humidity in stand-alone simulations may be responsible for the SST biases in regional coupled *** with reanalysis data,the warmer (or colder) and moister (or dryer) lower troposphere simulated in CREM (RegCM3) produces less (or more) sea surface latent heat ***,the more unstable (or stable) lower troposphere produces less (or more) cloudiness at low-level,which increases (or decreases) the solar radiation reaching on the sea *** (RegCM3) forced by observed SST overestimates (or underestimates) the sea surface net heat flux,implying a potential warm (or cold) heat *** coupling with POM2000,the warm (or cold) heat source would further increase (or decrease) the *** biases of vertical profile of temperature and specific humidity may be ascribed to the different representation of cumulus convection in atmospheric models.

关键词： inter-comparison of regional coupling different atmospheric component western North Pacific summer monsoon model biases

Convection-Permitting Simulations of Current and Future Climates over the Tibetan Plateau

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Advances in Atmospheric Sciences 2024年第10期41卷 1901-1916页

作者： Liwei ZOU tianjun zhou LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

The Tibetan Plateau(TP)region,also known as the“Asian water tower”,provides a vital water resource for downstream *** studies of water cycle changes over the TP have been conducted with climate models of coarse resolution in which deep convection must be *** this study,we present results from a first set of highresolution climate change simulations that permit convection at approximately 3.3-km grid spacing,with a focus on the TP,using the Icosahedral Nonhydrostatic Weather and Climate Model(ICON).Two 12-year simulations were performed,consisting of a retrospective simulation(2008–20)with initial and boundary conditions from ERA5 reanalysis and a pseudoglobal warming projection driven by modified reanalysis-derived initial and boundary conditions by adding the monthly CMIP6 ensemble-mean climate change under the SSP5-8.5 *** retrospective simulation shows overall good performance in capturing the seasonal precipitation and surface air *** the central and eastern TP,the average biases in precipitation(temperature)are less than−0.34 mm d−1(−1.1℃)throughout the *** simulated biases over the TP are ***(wet)biases are found in summer(winter)above 5500 *** future climate simulation suggests that the TP will be wetter and warmer under the SSP5-8.5 *** general features of projected changes in ICON are comparable to the CMIP6 ensemble projection,but the added value from kilometer-scale modeling is evident in both precipitation and temperature projections over complex topographic *** ICON-downscaled climate change simulations provide a high-resolution dataset to the community for the study of regional climate changes and impacts over the TP.

关键词： dynamical downscaling convection-permitting Tibetan Plateau pseudo-global warming

Precipitation Changes in Wet and Dry Seasons over the 20th Century Simulated by Two Versions of the FGOALS Model

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Advances in Atmospheric Sciences 2015年第6期32卷 839-854页

作者： MA Shuangmei zhou tianjun State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Climate Change Research Center Chinese Academy of Sciences

Seasonal precipitation changes over the globe during the 20th century simulated by two versions of the Flexible Global Ocean-Atmosphere-Land System （FGOALS） model are assessed. The two model versions differ in terms of their AGCM component, but the remaining parts of the system are almost identical. Both models reasonably reproduce the mean-state features of the timings of the wet and dry seasons and related precipitation amounts, with pattern correlation coefficients of 0.65-0.84 with observations. Globally averaged seasonal precipitation changes are analyzed. The results show that wet sea- sons get wetter and the annual range （precipitation difference between wet and dry seasons） increases during the 20th century in the two models, with positive trends covering most parts of the globe, which is consistent with observations. However, both models show a moistening dry season, which is opposite to observations. Analysis of the globally averaged moisture budget in the historical climate simulations of the two models shows little change in the horizontal moisture advection in both the wet and dry seasons. The globally averaged seasonal precipitation changes are mainly dominated by the changes in evaporation and vertical moisture advection. Evaporation and vertical moisture advection combine to make wet seasons wetter and enhance the annual range. In the dry season, the opposite change of evaporation and vertical moisture advection leads to an insignificant change in precipitation. Vertical moisture advection is the most important term that determines the changes in precipitation, wherein the thermodynamic component is dominant and the dynamic component tends to offset the effect of the thermodynamic component.

关键词： 20th century historical climate simulation FGOALS-g2 FGOALS-s2 wet season dry season precipitation change water vapor budget diagnosis

Seasonal Variation and Physical Properties of the Cloud System over Southeastern China Derived from Cloud Sat Products

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Advances in Atmospheric Sciences 2015年第5期32卷 659-670页

作者： GUO Zhun zhou tianjun State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Climate Change Research Center Chinese Academy of Sciences Joint Center for Global Change Studies

Based on the National Centers for Environmental Prediction（NCEP） and Climate Prediction Center（CPC） Merged Analysis of Precipitation（CMAP） data and Cloud Sat products, the seasonal variations of the cloud properties, vertical occurrence frequency, and ice water content of clouds over southeastern China were investigated in this study. In the Cloud Sat data, a significant alternation in high or low cloud patterns was observed from winter to summer over southeastern China. It was found that the East Asian Summer Monsoon（EASM） circulation and its transport of moisture leads to a conditional instability, which benefits the local upward motion in summer, and thereby results in an increased amount of high cloud. The deep convective cloud centers were found to coincide well with the northward march of the EASM, while cirrus lagged slightly behind the convection center and coincided well with the outflow and meridional wind divergence of the EASM. Analysis of the radiative heating rates revealed that both the plentiful summer moisture and higher clouds are effective in destabilizing the atmosphere. Moreover, clouds heat the mid-troposphere and the cloud radiative heating is balanced by adiabatic cooling through upward motion, which causes meridional wind by the Sverdrup balance. The cloud heating–forced circulation was observed to coincide well with the EASM circulation, serving as a positive effect on EASM circulation.

关键词： East Asian summer monsoon seasonal cycle Cloud Sat cloud