Land-sea coordination is a crucial strategy for ensuring the sustainable and rapid development of coastal cities.Assessing the level of land-sea coordination is vital for understanding the degree of coordination and i...Land-sea coordination is a crucial strategy for ensuring the sustainable and rapid development of coastal cities.Assessing the level of land-sea coordination is vital for understanding the degree of coordination and identifying imbalances within land-sea systems.However,empirical research in this area remains scarce,necessitating further investigation.Using coastline,land use,and socio-economic data for the Taizhou coastal zone of China across seven time periods from 1990 to 2021,this study analyzed the spatiotemporal characteristics of coastal zone development intensity,developed a comprehensive evaluation model for land-sea coordination,and examined its evolutionary dynamics.The results indicated a substantial rise in development intensity within the Taizhou coastal zone,accompanied by significant alterations in coastline morphology and structure.These changes included a marked reduction in the extent of natural coastline and a corresponding expansion of artificial coastline.The intensity of coastal land use also increased,primarily driven by the expansion of built-up areas and aquaculture ponds.The development level of land-sea systems,as well as the overall coordination of the Taizhou land-sea system,demonstrated a consistent upward trend,advancing from basic to intermediate coordination.These findings provide actionable insights for enhancing land-sea coordination strategies to support the sustainable development of coastal cities.展开更多
In this work, the SCSMEX data are used to diagnose and compare the local land-sea thermal conditions, with the focus of discussion on possible influences of thermal forcing of the western Pacific and the Tibetan Plate...In this work, the SCSMEX data are used to diagnose and compare the local land-sea thermal conditions, with the focus of discussion on possible influences of thermal forcing of the western Pacific and the Tibetan Plateau on the onset and development of summer monsoon in 1998. Results show a close relationship between the distribution of the heat sources and the land-sea contrast. Due to the blocking effect of terrain, main maximum zones of the heat sources in areas with more evident north-south land-sea contrast are more obviously southward located than those exclusively with oceans. The surface heating is characterized with apparent seasonal variation and difference between land and sea. The relationship between the western Pacific and the onset of summer monsoon is reflected in the variations of the sea surface temperature (SST) and the latent heat. The influence mechanism of the Tibetan Plateau during the summer monsoon is different: it is dominated by sensible heating during the South China Sea monsoon and by condensed latent heating during the Indian monsoon.展开更多
The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two id...The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two ideal tests in s-p regional climate model. The result shows that warm SST in the SCS in winter and spring is favorable for the formation of monsoon circulation throughout all levels of the atmosphere over the sea, which hastens the onset of SCS summer monsoon. The effects of cold SST are generally the opposite. The local land-sea contrast in the SCS is one of the possible reasons for SCS summer monsoon onset. Superposed upon large-scale land-sea thermodynamic differences, it facilitates the formation of out-breaking onset characteristics of SCS summer monsoon in the SCS area.展开更多
Land-sea breeze(LSB)is an atmospheric mesoscale circulation that occurs in the vicinity of the coast and is caused by uneven heating resulting from the difference in specific heat capacity between the sea and land sur...Land-sea breeze(LSB)is an atmospheric mesoscale circulation that occurs in the vicinity of the coast and is caused by uneven heating resulting from the difference in specific heat capacity between the sea and land surfaces.The circulation structure of LSB was quantitatively investigated with a Doppler wind lidar Windcube100s on the west coast of the Yellow Sea for the first time.The time of observation was 31 August to 28 September 2018.It was found that the height of LSB development was 700 m to 1300 m.The duration of conversion of LSB was between 6 h and 8 h.The biggest average horizontal sea-breeze wind speed at 425 m was 5.6 m s^(-1),and at 375 m it was 4.5 m s^(-1).During the conversion process from sea breeze to land breeze,the maximum wind shear exponent was 2.84 at 1300 m altitude.During the conversion process from land breeze to sea breeze,the maximum wind shear exponent was 1.28 at 700 m altitude.The differences in wind shear exponents between sea-breeze and landbreeze systems were between 0.2 and 3.6 at the same altitude.The maximum value of the wind shear exponent can reflect the height of LSB development.展开更多
The effects of the land-sea distribution, the topography and the diurnal change of the solar radiation on the summer monsoon modelings are studied by use of a coupled modeling system with a 5-layer primitive equation ...The effects of the land-sea distribution, the topography and the diurnal change of the solar radiation on the summer monsoon modelings are studied by use of a coupled modeling system with a 5-layer primitive equation model of the atmosphere and a 2-layer soil or ocean thermodynamic model which are all solved in a zonal model domain between 60°S and 60°N. The results of numerical simulations show that the quasi-stationary patterns of the mean monsoon circulations are mainly affected by the land-sea distribution and the topography, the effect of the diurnal change is the secondary. However, the inclusion of the diurnal change into the model system may improve the intensity of the simulated monsoon circulation, it can influence the distributive pattern of precipitation to a larger extent,without the diurnal change precipitation in the interior of land would decrease and in the coastal regions it would increase.展开更多
The effects of the land-sea contrast and the topography on the climatic properties are simulated rn this paper by use of a p- a incorporated coordinate system mode! in a zonal domain.In this paper we firstly discuss t...The effects of the land-sea contrast and the topography on the climatic properties are simulated rn this paper by use of a p- a incorporated coordinate system mode! in a zonal domain.In this paper we firstly discuss the statistical features of the model and find that the capability of the model is stable,with the same land-sea distribution and topography seven monthly mean climate states are close to one another,their variance is even less than the initial one.Secondly,we focally discuss the effects of the land-sea contrast and the topography on the modeled climate fields.It is pointed out that the land-sea contrast and the topography influence the atmosphere mainly through the heating ef-fect and the former has larger influences on the simulated large scale climate fields than the latter.展开更多
This study aims to provide a quantitative basis for the precision emission reduction of land-based total nitrogen(TN)pollutants in Laizhou Bay(LZB),China.The total maximum allocated load(TMAL)of TN pollutants within j...This study aims to provide a quantitative basis for the precision emission reduction of land-based total nitrogen(TN)pollutants in Laizhou Bay(LZB),China.The total maximum allocated load(TMAL)of TN pollutants within jurisdictions around LZB was calculated using the stepwise simulation-optimization model after the division of source units,simulation of the concentration response matrix,setting of the additional constraint conditions for stepwise source units,and calculation of TMAL.The load reduction allocation system for jurisdictions can be constructed on the basis of the TMAL and the load monitored or statistics.The index system for TN emission reduction included indices for two groups:a fixed index of marine emission reduction rate for jurisdictions,which was 11.93%on average;and threshold indices of pollution prevention rate at sources,the increment rate of pollution removal by municipal sewage treatment systems,and watershed retention of jurisdictions,which were 7.43%,1.58%,and 1.09%on average,respectively.Efficiency of pollutant reduction can be evaluated using a 3D hydrodynamic-water quality model.Simulation results showed that the precise reduction indicators achieved the seawater quality improvement target of LZB 5 years earlier than the equal proportion reduction indicators currently used in LZB Basin.展开更多
The 2003-006 observations were utilized to analyze the surface characteristics of summer land-sea breezes along the coastland of Guangxi and the Weather Research and Forecast model was applied to simulate the breeze s...The 2003-006 observations were utilized to analyze the surface characteristics of summer land-sea breezes along the coastland of Guangxi and the Weather Research and Forecast model was applied to simulate the breeze structure on August 1-2, 2006. Results show that 1） the intensity and distributions of the breezes reproduced from improved urban underlying surface were close to observations. In the daytime the coastwise urban band was a convergent belt of sea breeze, corresponding to the centers of torrential rains; in the nighttime hours the surface of the Gulf of Tonkin （the Vietnamese name） or the Northern Bay （the Chinese name） acted as a convergent zone of land breezes, likely to produce convective cloud cluster; 2） the experiment on urbanization showed the heat island effect enhancing （weakening） the sea （land） breeze development. Furthermore, the heat island effect mitigated the atmospheric cooling via radiation over the cities in the night, weakening sinking motion correspondingly, thereby suppressing the dominant factor responsible for the steady development of temperature inversion. As a result, the inversion vigor was reduced greatly, but nevertheless no strong effect of the decreased subsidence was found upon the inversion height.展开更多
介绍了“地球系统与全球变化”重点专项项目“中国极端天气气候事件的形成机理及其预测和归因”2025年度的主要成果。1)发展了群发性极端温度事件的检测识别方法并构建了数据集,揭示了群发性极端温度事件、暖季极端高温-降水复合事件的...介绍了“地球系统与全球变化”重点专项项目“中国极端天气气候事件的形成机理及其预测和归因”2025年度的主要成果。1)发展了群发性极端温度事件的检测识别方法并构建了数据集,揭示了群发性极端温度事件、暖季极端高温-降水复合事件的变化特征及北美-东亚冬季极端低温的空间复合特征,并开展了极端温度变化的归因研究。2)阐明了东亚冬季气温反相事件、2022年夏季长江流域极端高温等典型极端事件的环流特征及动力学机理。3)提出了MJO(Madden-Julian Oscillation)遥相关的动力学新机制,发现夏季MJO在印度洋停留时间3倍增长并加剧了极端气候事件风险;揭示了印度洋快速增暖、春季重新发展增强的La Ni a对中国极端气候的影响,探讨了不同海盆海温异常对夏季高温干旱复合事件的影响,发现华北秋季群发性极端降水增强与关键区北极海冰减少存在密切联系。4)探讨了陆面蒸散发与干旱变化机理、高温干旱复合极端事件的形成机理、积雪与土壤湿度的气候反馈效应以及陆气耦合对极端气候和大尺度环流的影响。5)建立了干旱、极端高温、暴雨-热浪复合极端事件、极端低温次季节-年际预测的物理统计预测模型,发展了极端温度次季节反转的预测方法,在一定程度上改善了中国极端天气气候事件的预测水平。展开更多
Using a monthly precipitation dataset of 160 stations over China and a daily and monthly National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis dataset from 1961 ...Using a monthly precipitation dataset of 160 stations over China and a daily and monthly National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis dataset from 1961 to 2006, we here define an East Asian land-sea atmospheric heat source difference index ILSQD and investigate its relationship to summer rainfall in China and East Asian general circulation. The results show that ILSQD more closely reflects the anomalous variations in summer monsoon phenomena; in the high-index (HI) cases, the strong low-level southerlies over East China and the strong high-level westerlies over middle latitudes indicate an active summer monsoon, and vice versa in the low-index (LI) cases. This index also reflects summer rainfall anomalies over East China; in the HI (LI) cases rainfall increases (decreases) over North China and at the same time decreases (increases) over the mid-lower Yangtze River valley and the southern Yangtze River. Hence, ILSQD can be utilized as a summer monsoon index. There is also remarkable correlation between ILSQD in March and the following summer rainfall over the mid-lower Yangtze River valley. Finally, the Community Atmospheric Model Version 3.1 (CAM3.1) of NCAR is used to run numerical experiments, which verify that the anomalous summer precipitation in simulations is similar to that of diagnosis analysis based on the anomalous summer atmospheric heating forcing. Similarly, the atmospheric heating rate in March can force summer rainfall anomalies in the simulations just as observed in the data.展开更多
This paper proposes an index of land-sea thermal difference(ILSTD)that describes its zonal and meridional strength responsible for East Asian monsoon circulation to study its relation to the East Asian monsoon circula...This paper proposes an index of land-sea thermal difference(ILSTD)that describes its zonal and meridional strength responsible for East Asian monsoon circulation to study its relation to the East Asian monsoon circulation and the summer rainfall over China on an interannual basis.Results are as follows:(1)ILSTD can be used to measure the strength of East Asian summer monsoon in such a way that the strong(weak)ILSTD years are associated with strong(weak)summer monsoon circulation.(2)The index also reflects well summer rainfall anomaly over the eastern part of China. In the strong index years,rain belt is mainly located over the northern China,and serious drought emerges in the Jianghuai valleys and mid-lower reaches of the Changjiang River,along with increase of rainfall in North and South China,but in the weak years it is contrary.(3)Besides,the index has obvious QBO and quasi 4-year oscillations,but the periods and amplitudes have significant changes on an interdecadal basis.展开更多
Currently,China has entered the period of land-sea coordinated planning,yet there are few studies on the interaction between land use intensity and sea eco-security in coastal zones.Therefore,taking the coastal zone o...Currently,China has entered the period of land-sea coordinated planning,yet there are few studies on the interaction between land use intensity and sea eco-security in coastal zones.Therefore,taking the coastal zone of Xiamen as an example,this paper develops a comprehensive system to evaluate the coupling degree between spatial utilization intensity and eco-security based on the coupling degree theory in physics.Then the paper quantitatively analyzes and identifies the coupling coordination degree of various shore sections into four categories:well-coordinated and highly-coupled,moderately-coordinated and moderately-coupled,moderately-coordinated and slightly-coupled,and primary-level coordinated and slightly-coupled.Finally,it puts forward spatial planning guidelines for the four types of shore sections on the basis of land-sea coordination.Specifically,reserved ecological section should follow the principle of giving priority to the marine ecosystem,and strictly protecting the ecosystem and controlling development;ecological promotion section should follow the principle of optimizing land development based on the sea resources,and reserving space for transformation;restricted development section should follow the principle of land-sea balance,and only allowing low-impact development activities to achieve synchronous land-sea development;development leverage section should follow the principle of optimizing marine development based on land resources,giving full play to the advantages of coastal resources and featured coastal space,and achieving spatial optimization in accordance with people-oriented principles and local conditions.This research intends to provide a scientific basis for coastal zone planning and decision-making and a paradigm guide for gulf cities to coordinate the marine ecosystem and land development.展开更多
In general,the tropical cyclone(TC) activity is considered to be influenced by the heat content of underlying ocean,vertical shear of horizontal wind,vorticity in the low troposphere,moisture in the troposphere,and fa...In general,the tropical cyclone(TC) activity is considered to be influenced by the heat content of underlying ocean,vertical shear of horizontal wind,vorticity in the low troposphere,moisture in the troposphere,and favorable condition for deep convection development.However,these factors by nature merely present the internal factors of either atmosphere or ocean which influence the TC activity.In fact,the energy budget of the Earth system and its variation,modulated by the land-sea thermal contrast,are the intrinsic reasons responsible for the variation of TC activity.Here we investigate the modulation of diabatic heating distribution associated with the land-sea thermal contrast on the distribution of TC activity energy source and sink as well as the seasonality.An accumulated energy increment index(AEI) is defined using the TC best track data,and the energy sources and sinks of TC activity are then diagnosed effectively and practically according to the distribution of AEI.Results show that the thermal contrast of land and ocean is the primary reason for asymmetric distribution of TC activity about the Equator as well as the zonally asymmetric distribution of TC activity.The energy sources of TC activity are dominated by condensation heating of deep convection or double-dominant heating,which includes the condensation heating and cooling of longwave radiation(LO),while the sink areas are dominated by LO.The large scale diabatic heating associated with land-sea thermal contrast results in more favorable conditions for TC activity over the west part of oceans than those over the east parts.Moreover,the intensity of interaction of different diabatic heating over the west and east parts of ocean is also affected by the zonal scale of the oceans,which induces the difference of TC activity over the western North Pacific(WNP) and North Atlantic(ATL).The favorable westerlies and anticyclonic vertical shear associated with the tropical zonally asymmetric diabatic heating also contribute to the most intense TC activity over the WNP.The variation of large scale diabatic heating modulates the annual cycle of TC energy sources and sinks.In particular,the annual cycle over the WNP is the most typical one among the three basins(the WNP,the south Indian Ocean,and western South Pacific) that are characterized by the meridional shift of the energy sources and sinks.However,sources over the eastern North Pacific tend to extend westward and withdraw eastward associated with the variation of LO,while over the ATL,sources always merge from small pieces into a big one as the different diabatic heating over its west and east parts interacts with each other.Over the boreal Indian Ocean,the subcontinental scale land-sea heating contrast modifies the large scale circulation,and consequently contributes to the bimodal annual cycle of TC activity.In summary,TC activities are closely related to the interaction among various components of the climate system more than the atmosphere and ocean.展开更多
基金Under the auspices of National Natural Science Fundation(No.42276234,41976209,42206236)。
文摘Land-sea coordination is a crucial strategy for ensuring the sustainable and rapid development of coastal cities.Assessing the level of land-sea coordination is vital for understanding the degree of coordination and identifying imbalances within land-sea systems.However,empirical research in this area remains scarce,necessitating further investigation.Using coastline,land use,and socio-economic data for the Taizhou coastal zone of China across seven time periods from 1990 to 2021,this study analyzed the spatiotemporal characteristics of coastal zone development intensity,developed a comprehensive evaluation model for land-sea coordination,and examined its evolutionary dynamics.The results indicated a substantial rise in development intensity within the Taizhou coastal zone,accompanied by significant alterations in coastline morphology and structure.These changes included a marked reduction in the extent of natural coastline and a corresponding expansion of artificial coastline.The intensity of coastal land use also increased,primarily driven by the expansion of built-up areas and aquaculture ponds.The development level of land-sea systems,as well as the overall coordination of the Taizhou land-sea system,demonstrated a consistent upward trend,advancing from basic to intermediate coordination.These findings provide actionable insights for enhancing land-sea coordination strategies to support the sustainable development of coastal cities.
基金 Part I: Research on the Formation Mechnism and Prediction Theory of Severe Climate Disasters in China (G199804900) 揂nalysis and Mechanism Study of Regional Climate Changes in China? a key projec
文摘In this work, the SCSMEX data are used to diagnose and compare the local land-sea thermal conditions, with the focus of discussion on possible influences of thermal forcing of the western Pacific and the Tibetan Plateau on the onset and development of summer monsoon in 1998. Results show a close relationship between the distribution of the heat sources and the land-sea contrast. Due to the blocking effect of terrain, main maximum zones of the heat sources in areas with more evident north-south land-sea contrast are more obviously southward located than those exclusively with oceans. The surface heating is characterized with apparent seasonal variation and difference between land and sea. The relationship between the western Pacific and the onset of summer monsoon is reflected in the variations of the sea surface temperature (SST) and the latent heat. The influence mechanism of the Tibetan Plateau during the summer monsoon is different: it is dominated by sensible heating during the South China Sea monsoon and by condensed latent heating during the Indian monsoon.
基金National Natural Science Foundation of China (40175021 40233037)
文摘The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two ideal tests in s-p regional climate model. The result shows that warm SST in the SCS in winter and spring is favorable for the formation of monsoon circulation throughout all levels of the atmosphere over the sea, which hastens the onset of SCS summer monsoon. The effects of cold SST are generally the opposite. The local land-sea contrast in the SCS is one of the possible reasons for SCS summer monsoon onset. Superposed upon large-scale land-sea thermodynamic differences, it facilitates the formation of out-breaking onset characteristics of SCS summer monsoon in the SCS area.
基金supported by the National Key Research and Development Program of China[Grant number 2016YFC0202001]the Chinese Academy of Sciences Strategic Priority Research Program[Grant number XDA23020301]the National Natural Science Foundation of China[Grant number 41375036]。
文摘Land-sea breeze(LSB)is an atmospheric mesoscale circulation that occurs in the vicinity of the coast and is caused by uneven heating resulting from the difference in specific heat capacity between the sea and land surfaces.The circulation structure of LSB was quantitatively investigated with a Doppler wind lidar Windcube100s on the west coast of the Yellow Sea for the first time.The time of observation was 31 August to 28 September 2018.It was found that the height of LSB development was 700 m to 1300 m.The duration of conversion of LSB was between 6 h and 8 h.The biggest average horizontal sea-breeze wind speed at 425 m was 5.6 m s^(-1),and at 375 m it was 4.5 m s^(-1).During the conversion process from sea breeze to land breeze,the maximum wind shear exponent was 2.84 at 1300 m altitude.During the conversion process from land breeze to sea breeze,the maximum wind shear exponent was 1.28 at 700 m altitude.The differences in wind shear exponents between sea-breeze and landbreeze systems were between 0.2 and 3.6 at the same altitude.The maximum value of the wind shear exponent can reflect the height of LSB development.
文摘The effects of the land-sea distribution, the topography and the diurnal change of the solar radiation on the summer monsoon modelings are studied by use of a coupled modeling system with a 5-layer primitive equation model of the atmosphere and a 2-layer soil or ocean thermodynamic model which are all solved in a zonal model domain between 60°S and 60°N. The results of numerical simulations show that the quasi-stationary patterns of the mean monsoon circulations are mainly affected by the land-sea distribution and the topography, the effect of the diurnal change is the secondary. However, the inclusion of the diurnal change into the model system may improve the intensity of the simulated monsoon circulation, it can influence the distributive pattern of precipitation to a larger extent,without the diurnal change precipitation in the interior of land would decrease and in the coastal regions it would increase.
基金Supported by the National Key Project of Fundamental Research "Climate DynamicsClimate Prediction Theory"the National Natural Science Foundation of China
文摘The effects of the land-sea contrast and the topography on the climatic properties are simulated rn this paper by use of a p- a incorporated coordinate system mode! in a zonal domain.In this paper we firstly discuss the statistical features of the model and find that the capability of the model is stable,with the same land-sea distribution and topography seven monthly mean climate states are close to one another,their variance is even less than the initial one.Secondly,we focally discuss the effects of the land-sea contrast and the topography on the modeled climate fields.It is pointed out that the land-sea contrast and the topography influence the atmosphere mainly through the heating ef-fect and the former has larger influences on the simulated large scale climate fields than the latter.
基金the fund provided by the Basic Scientific Research Funds of Dalian University of Technology(No.DUT21RC(3)035)the Open Funds of Key Laboratory of Estuarine and Coastal Environment(No.HKHA2022001)。
文摘This study aims to provide a quantitative basis for the precision emission reduction of land-based total nitrogen(TN)pollutants in Laizhou Bay(LZB),China.The total maximum allocated load(TMAL)of TN pollutants within jurisdictions around LZB was calculated using the stepwise simulation-optimization model after the division of source units,simulation of the concentration response matrix,setting of the additional constraint conditions for stepwise source units,and calculation of TMAL.The load reduction allocation system for jurisdictions can be constructed on the basis of the TMAL and the load monitored or statistics.The index system for TN emission reduction included indices for two groups:a fixed index of marine emission reduction rate for jurisdictions,which was 11.93%on average;and threshold indices of pollution prevention rate at sources,the increment rate of pollution removal by municipal sewage treatment systems,and watershed retention of jurisdictions,which were 7.43%,1.58%,and 1.09%on average,respectively.Efficiency of pollutant reduction can be evaluated using a 3D hydrodynamic-water quality model.Simulation results showed that the precise reduction indicators achieved the seawater quality improvement target of LZB 5 years earlier than the equal proportion reduction indicators currently used in LZB Basin.
基金Natural Science Foundation of China (40975037 40775033)
文摘The 2003-006 observations were utilized to analyze the surface characteristics of summer land-sea breezes along the coastland of Guangxi and the Weather Research and Forecast model was applied to simulate the breeze structure on August 1-2, 2006. Results show that 1） the intensity and distributions of the breezes reproduced from improved urban underlying surface were close to observations. In the daytime the coastwise urban band was a convergent belt of sea breeze, corresponding to the centers of torrential rains; in the nighttime hours the surface of the Gulf of Tonkin （the Vietnamese name） or the Northern Bay （the Chinese name） acted as a convergent zone of land breezes, likely to produce convective cloud cluster; 2） the experiment on urbanization showed the heat island effect enhancing （weakening） the sea （land） breeze development. Furthermore, the heat island effect mitigated the atmospheric cooling via radiation over the cities in the night, weakening sinking motion correspondingly, thereby suppressing the dominant factor responsible for the steady development of temperature inversion. As a result, the inversion vigor was reduced greatly, but nevertheless no strong effect of the decreased subsidence was found upon the inversion height.
文摘介绍了“地球系统与全球变化”重点专项项目“中国极端天气气候事件的形成机理及其预测和归因”2025年度的主要成果。1)发展了群发性极端温度事件的检测识别方法并构建了数据集,揭示了群发性极端温度事件、暖季极端高温-降水复合事件的变化特征及北美-东亚冬季极端低温的空间复合特征,并开展了极端温度变化的归因研究。2)阐明了东亚冬季气温反相事件、2022年夏季长江流域极端高温等典型极端事件的环流特征及动力学机理。3)提出了MJO(Madden-Julian Oscillation)遥相关的动力学新机制,发现夏季MJO在印度洋停留时间3倍增长并加剧了极端气候事件风险;揭示了印度洋快速增暖、春季重新发展增强的La Ni a对中国极端气候的影响,探讨了不同海盆海温异常对夏季高温干旱复合事件的影响,发现华北秋季群发性极端降水增强与关键区北极海冰减少存在密切联系。4)探讨了陆面蒸散发与干旱变化机理、高温干旱复合极端事件的形成机理、积雪与土壤湿度的气候反馈效应以及陆气耦合对极端气候和大尺度环流的影响。5)建立了干旱、极端高温、暴雨-热浪复合极端事件、极端低温次季节-年际预测的物理统计预测模型,发展了极端温度次季节反转的预测方法,在一定程度上改善了中国极端天气气候事件的预测水平。
基金supported by National Natural Science Foundation of China (Grant Nos.90711003,40505014,40805035 and 40633018)
文摘Using a monthly precipitation dataset of 160 stations over China and a daily and monthly National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis dataset from 1961 to 2006, we here define an East Asian land-sea atmospheric heat source difference index ILSQD and investigate its relationship to summer rainfall in China and East Asian general circulation. The results show that ILSQD more closely reflects the anomalous variations in summer monsoon phenomena; in the high-index (HI) cases, the strong low-level southerlies over East China and the strong high-level westerlies over middle latitudes indicate an active summer monsoon, and vice versa in the low-index (LI) cases. This index also reflects summer rainfall anomalies over East China; in the HI (LI) cases rainfall increases (decreases) over North China and at the same time decreases (increases) over the mid-lower Yangtze River valley and the southern Yangtze River. Hence, ILSQD can be utilized as a summer monsoon index. There is also remarkable correlation between ILSQD in March and the following summer rainfall over the mid-lower Yangtze River valley. Finally, the Community Atmospheric Model Version 3.1 (CAM3.1) of NCAR is used to run numerical experiments, which verify that the anomalous summer precipitation in simulations is similar to that of diagnosis analysis based on the anomalous summer atmospheric heating forcing. Similarly, the atmospheric heating rate in March can force summer rainfall anomalies in the simulations just as observed in the data.
基金Supported by the South China Sea Monsoon Experiment,Climbing Programme"A"of China.
文摘This paper proposes an index of land-sea thermal difference(ILSTD)that describes its zonal and meridional strength responsible for East Asian monsoon circulation to study its relation to the East Asian monsoon circulation and the summer rainfall over China on an interannual basis.Results are as follows:(1)ILSTD can be used to measure the strength of East Asian summer monsoon in such a way that the strong(weak)ILSTD years are associated with strong(weak)summer monsoon circulation.(2)The index also reflects well summer rainfall anomaly over the eastern part of China. In the strong index years,rain belt is mainly located over the northern China,and serious drought emerges in the Jianghuai valleys and mid-lower reaches of the Changjiang River,along with increase of rainfall in North and South China,but in the weak years it is contrary.(3)Besides,the index has obvious QBO and quasi 4-year oscillations,but the periods and amplitudes have significant changes on an interdecadal basis.
基金funded by the Youth Program of National Natural Science Foundation of China(51708471).
文摘Currently,China has entered the period of land-sea coordinated planning,yet there are few studies on the interaction between land use intensity and sea eco-security in coastal zones.Therefore,taking the coastal zone of Xiamen as an example,this paper develops a comprehensive system to evaluate the coupling degree between spatial utilization intensity and eco-security based on the coupling degree theory in physics.Then the paper quantitatively analyzes and identifies the coupling coordination degree of various shore sections into four categories:well-coordinated and highly-coupled,moderately-coordinated and moderately-coupled,moderately-coordinated and slightly-coupled,and primary-level coordinated and slightly-coupled.Finally,it puts forward spatial planning guidelines for the four types of shore sections on the basis of land-sea coordination.Specifically,reserved ecological section should follow the principle of giving priority to the marine ecosystem,and strictly protecting the ecosystem and controlling development;ecological promotion section should follow the principle of optimizing land development based on the sea resources,and reserving space for transformation;restricted development section should follow the principle of land-sea balance,and only allowing low-impact development activities to achieve synchronous land-sea development;development leverage section should follow the principle of optimizing marine development based on land resources,giving full play to the advantages of coastal resources and featured coastal space,and achieving spatial optimization in accordance with people-oriented principles and local conditions.This research intends to provide a scientific basis for coastal zone planning and decision-making and a paradigm guide for gulf cities to coordinate the marine ecosystem and land development.
基金supported jointly by the National Basic Research Program of China(Grant Nos. 2010CB950403,2012CB956003 and 2012CB417203)the National Natural Science Foundation of China (Grant Nos. 40925015 and41075071)
文摘In general,the tropical cyclone(TC) activity is considered to be influenced by the heat content of underlying ocean,vertical shear of horizontal wind,vorticity in the low troposphere,moisture in the troposphere,and favorable condition for deep convection development.However,these factors by nature merely present the internal factors of either atmosphere or ocean which influence the TC activity.In fact,the energy budget of the Earth system and its variation,modulated by the land-sea thermal contrast,are the intrinsic reasons responsible for the variation of TC activity.Here we investigate the modulation of diabatic heating distribution associated with the land-sea thermal contrast on the distribution of TC activity energy source and sink as well as the seasonality.An accumulated energy increment index(AEI) is defined using the TC best track data,and the energy sources and sinks of TC activity are then diagnosed effectively and practically according to the distribution of AEI.Results show that the thermal contrast of land and ocean is the primary reason for asymmetric distribution of TC activity about the Equator as well as the zonally asymmetric distribution of TC activity.The energy sources of TC activity are dominated by condensation heating of deep convection or double-dominant heating,which includes the condensation heating and cooling of longwave radiation(LO),while the sink areas are dominated by LO.The large scale diabatic heating associated with land-sea thermal contrast results in more favorable conditions for TC activity over the west part of oceans than those over the east parts.Moreover,the intensity of interaction of different diabatic heating over the west and east parts of ocean is also affected by the zonal scale of the oceans,which induces the difference of TC activity over the western North Pacific(WNP) and North Atlantic(ATL).The favorable westerlies and anticyclonic vertical shear associated with the tropical zonally asymmetric diabatic heating also contribute to the most intense TC activity over the WNP.The variation of large scale diabatic heating modulates the annual cycle of TC energy sources and sinks.In particular,the annual cycle over the WNP is the most typical one among the three basins(the WNP,the south Indian Ocean,and western South Pacific) that are characterized by the meridional shift of the energy sources and sinks.However,sources over the eastern North Pacific tend to extend westward and withdraw eastward associated with the variation of LO,while over the ATL,sources always merge from small pieces into a big one as the different diabatic heating over its west and east parts interacts with each other.Over the boreal Indian Ocean,the subcontinental scale land-sea heating contrast modifies the large scale circulation,and consequently contributes to the bimodal annual cycle of TC activity.In summary,TC activities are closely related to the interaction among various components of the climate system more than the atmosphere and ocean.
