PM_(2.5) and black carbon(BC)are important air pollutants impacting radiation balance,air quality,health,and ecosystems.Ozone(O_(3))levels are increasing despite decreases in other pollutants,posing a challenge for po...PM_(2.5) and black carbon(BC)are important air pollutants impacting radiation balance,air quality,health,and ecosystems.Ozone(O_(3))levels are increasing despite decreases in other pollutants,posing a challenge for pollution control,especially in coastal cities like Zhoushan,where the monsoonal climate can exacerbate PM_(2.5) and ozone pollution.This study conducted continuous online measurements of major atmospheric pollutants in Zhoushan,Zhejiang Province,in 2020.The results indicate that the highest contribution from local air masses in Zhoushan is observed in spring,accounting for 17.7%,while the greatest average contribution from northern Zhejiang Province,Jiangsu Province,and Shanghai occurs in winter,at 18.5%.Pollutant concentrationswere seasonally variable,with PM_(2.5),BC,and sulfur dioxide concentrations 56.6%,36%,and 58.2%higher in the cold season compared to the warm season.The O_(3) in spring is approximately 50%higher than that in summer.Ship emissions significantly contributed to BC,nitrogen oxides(NO_(x)),and carbon monoxide in Zhoushan.In spring,PM_(2.5) sources included photochemical processes and northern air mass transport,while in winter,PM_(2.5) was due to regional transport.The inhibitory effect of PM_(2.5) on O_(3) formation in the Zhoushan area is relatively weak.Reducing NO_(x) emissions may increase O_(3),emphasizing the need for volatile organic compounds monitoring and regional control measures to improve air quality and ensure sustainable development in Zhoushan.展开更多
Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives ...Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives of billions who depend on or are affected by monsoons, as it is essential for the water cycle, food security, ecology, disaster prevention, and the economy of monsoon regions. Given the extensive literature on Asian monsoon climate prediction, we limit our focus to reviewing the seasonal prediction and predictability of the Asian Summer Monsoon (ASM). However, much of this review is also relevant to monsoon predictions in other seasons and regions. Over the past two decades, considerable progress has been made in the seasonal forecasting of the ASM, driven by an enhanced understanding of the sources of predictability and the dynamics of seasonal variability, along with advanced development in sophisticated models and technologies. This review centers on advances in understanding the physical foundation for monsoon climate prediction (section 2), significant findings and insights into the primary and regional sources of predictability arising from feedback processes among various climate components (sections 3 and 4), the effects of global warming and external forcings on predictability (section 5), developments in seasonal prediction models and techniques (section 6), the challenges and limitations of monsoon climate prediction (section 7), and emerging research trends with suggestions for future directions (section 8). We hope this review will stimulate creative activities to enhance monsoon climate prediction.展开更多
The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in Chin...The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant （scarce） rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong （weak） heat sources over the eastern Tibetan Plateau, while the abundant （scarce） rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak （strong） heat sources over the tropical western Pacific.展开更多
Using two datasets of global pentad grid precipitation and global 850 hPa geopotential height during 1979-2007,this study identified global monsoon troughs and global atmospheric centers of action (ACAs) on a pentad s...Using two datasets of global pentad grid precipitation and global 850 hPa geopotential height during 1979-2007,this study identified global monsoon troughs and global atmospheric centers of action (ACAs) on a pentad scale.The global monsoon troughs consist of planetary-scale monsoon troughs and peninsula-scale monsoon troughs.Forced by seasonal variations in solar radiation,the inter-tropical convergence zones (ITCZs) represent the planetary-scale monsoon troughs,which are active and shift over the tropical North Pacific,the tropical North Atlantic,and the tropical South Indian oceans.The peninsula-scale monsoon troughs are originated from regional land-sea topography and varied with contrasts in seasonal land-sea surface temperatures and precipitation.During the boreal summer,five peninsula-scale troughs and one planetary-scale trough are distributed in the Asia-Northwest Pacific (NWP) region.In total,22 troughs,nine monsoon troughs,and 19 ACAs in the lower troposphere were identified.Relevant ACAs may be useful in constructing regional monsoon and circulation indices.展开更多
The aim of the present study was to identify multi-decadal variability （MDV） relative to the current centennial global warming trend in available observation data.The centennial global wanning trend was first identi...The aim of the present study was to identify multi-decadal variability （MDV） relative to the current centennial global warming trend in available observation data.The centennial global wanning trend was first identified in the global mean surface temperature （STgm） data.The MDV was identified based on three sets of climate variables,including sea surface temperature （SST）,ocean temperature from the surface to 700 m,and the NCEP and ERA40 reanalysis datasets,respectively.All variables were detrended and low-pass filtered.Through three independent EOF analyses of the filtered variables,all results consistently showed two dominant modes,with their respective temporal variability resembling the Pacific Decadal Oscillation/Inter-decadal Pacific Oscillation （PDO/IPO） and the Atlantic Multi-decadal Oscillation （AMO）.The spatial structure of the PDO-like oscillation is characterized by an ENSO-like structure and hemispheric symmetric features.The structure associated with the AMO-like oscillation exhibits hemispheric asymmetric features with anomalous warm air over Eurasia and warm SST in the Atlantic and Pacific basin north of 10°S,and cold SST over the southern oceans.The Pacific and Atlantic MDV in upper-ocean temperature suggest that they are mutually linked.We also found that the PDO-like and AMO-like oscillations are almost equally important in global-scale MDV by EOF analyses.In the period 1975-2005,the evolution of the two oscillations has given rise to strong temperature trends and has contributed almost half of the STgm warming.Hereon,in the next decade,the two oscillations are expected to slow down the global warming trends.展开更多
Paleoclimate simulations usually require model runs over a very long time. The fast integration version of a state-of-the-art general circulation model （GCM）, which shares the same physical and dynamical processes b...Paleoclimate simulations usually require model runs over a very long time. The fast integration version of a state-of-the-art general circulation model （GCM）, which shares the same physical and dynamical processes but with reduced horizontal resolution and increased time step, is usually developed. In this study, we configure a fast version of an atmospheric GCM （AGCM）, the Grid Atmospheric Model of IAP/LASG （Institute of Atmospheric Physics/State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics）, at low resolution （GAMIL-L, hereafter）, and compare the simulation results with the NCEP/NCAR reanalysis and other data to examine its performance. GAMIL-L, which is derived from the original GAMIL, is a finite difference AGCM with 72 × 40 grids in longitude and latitude and 26 vertical levels. To validate the simulated climatology and variability, two runs were achieved. One was a 60-year control run with fixed climatological monthly sea surface temperature （SST） forcing, and the other was a 50-yr （1950-2000） integration with observational time-varying monthly SST forcing. Comparisons between these two cases and the reanalysis, including intra-seasonal and inter-annual variability are also presented. In addition, the differences between GAMIL-L and the original version of GAMIL are also investigated.The results show that GAMIL-L can capture most of the large-scale dynamical features of the atmosphere, especially in the tropics and mid latitudes, although a few deficiencies exist, such as the underestimated Hadley cell and thereby the weak strength of the Asia summer monsoon. However, the simulated mean states over high latitudes, especially over the polar regions, are not acceptable. Apart from dynamics, the thermodynamic features mainly depend upon the physical parameterization schemes. Since the physical package of GAMIL-L is exactly the same as the original high-resolution version of GAMIL, in which the NCAR Community Atmosphere Model （CAM2） physical package was used, there are only small differences between them in the precipitation and temperature fields. Because our goal is to develop a fast-running AGCM and employ it in the coupled climate system model of IAP/LASG for paleoclimate studies such as ENSO and Australia-Asia monsoon, particular attention has been paid to the model performances in the tropics. More model validations, such as those ran for the Southern Oscillation and South Asia monsoon, indicate that GAMIL-L is reasonably competent and valuable in this regard.展开更多
This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary la...This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.展开更多
The physical retrieval algorithm of atmospheric temperature and moisture distribution from the Atmospheric InfraRed Sounder （AIRS） radiances is presented. The retrieval algorithm is applied to AIRS clear-sky radianc...The physical retrieval algorithm of atmospheric temperature and moisture distribution from the Atmospheric InfraRed Sounder （AIRS） radiances is presented. The retrieval algorithm is applied to AIRS clear-sky radiance measurements. The algorithm employs a statistical retrieval followed by a subsequent nonlinear physical retrieval. The regression coefficients for the statistical retrieval are derived from a dataset of global radiosonde observations （RAOBs） comprising atmospheric temperature, moisture, and ozone profiles. Evaluation of the retrieved profiles is performed by a comparison with RAOBs from the Atmospheric Radiation Measurement （ARM） Program Cloud And Radiation Testbed （CART） in Oklahoma, U. S. A.. Comparisons show that the physically-based AIRS retrievals agree with the RAOBs from the ARM CART site with a Root Mean Square Error （RMSE） of 1K on average for temperature profiles above 850 hPa, and approximately 10% on average for relative humidity profiles. With its improved spectral resolution, AIRS depicts more detailed structure than the current Geostationary Operational Environmental Satellite （GOES） sounder when comparing AIRS sounding retrievals with the operational GOES sounding products.展开更多
NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its s...NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its surrounding area and precipitation in northwest China. Our main conclusions are as follows： （1） The horizontal distribution of 〈 Q1 〉 and its changing trend are dramatic over QXP in the summer. There are three strong centers of 〈 Q1 〉 over the south side of QXP with obvious differences in the amount of yearly precipitation and the number of heat sinks predominate in the arid and semi-arid regions of northwest China （NWC）, beside the northern QXP with an obvious higher intensity in years with less precipitation. （2） In the summer, the variation of the heat source＇s vertical structure is obviously different between greater and lesser precipitation years in eastern northwest China （ENWC）. The narrow heat sink belt forms between the northeast QXP and the southwestern part of Lake Baikal. In July and August of greater precipitation years, the heating center of the eastern QXP stays nearly over 35°N, and at 400 hPa of the eastern QXP, the strong upward motion of the heating center constructs a closed secondary vertical circulation cell over the northeast QXP （40~ 46~N）, which is propitious to add precipitation over the ENWC. Otherwise, the heating center shifts to the south of 30°N and disappears in July and August of lesser precipitation years, an opposite secondary circulation cell forms over the northeast QXP, which is a disadvantage for precipitation. Meanwhile, the secondary circulation cell in years with more or less precipitation over the ENWC is also related to the heat source over the Lake Baikal. （3） The vertical structure of the heat source over the western QXP has obvious differences between greater and lesser precipitation years in western northwest China in June and July. The strong/weak heat source over the western QXP produces relatively strong/weak ascending motion and correspondingly constructs a secondary circulation cell in lesser/greater precipitation years.展开更多
Based on the geographical circumstance, climate and the boundary layer meteorology features of the Pearl River Delta, a boundary layer concept model of the Pearl River Delta was built. The concept model consists of fo...Based on the geographical circumstance, climate and the boundary layer meteorology features of the Pearl River Delta, a boundary layer concept model of the Pearl River Delta was built. The concept model consists of four fundamental factors that affect the boundary layer meteorology of the Pearl River Delta and can convincingly explain the reason of the air quality change in the Pearl River Delta. The model can be used to the diffusion capability analysis, the air pollution potential forecasting or haze forecasting, etc.展开更多
This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent （SWE）, snow cover frequency ...This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent （SWE）, snow cover frequency （SCF）, and 500 hPa geopotential height data. It is found that the Eurasian SWE/SCF and circulation dominant modes are stably coupled from autumn to the subsequent spring.The temporal coherence of the seasonal evolution of the dominant modes is examined.The seasonal evolution of the Eurasian circulation and SWE dominant modes exhibit good coherence, whereas the evolution of the Eurasian SCF dominant mode is incoherent during the autumn-winter transition season. This incoherence is associated with a sign-change in the SCF anomalies in Europe during the autumn-winter transition season, which is related to the wind anomalies over Europe. In addition, the surface heat budget associated with the Eurasian SWE/SCF and circulation dominant modes is analyzed. The sensible heat flux （SHF） related to the wind-induced thermal advection dominates the surface heat budget from autumn to the subsequent spring, with the largest effect during winter. The surface net shortwave radiation is mainly modulated by snow cover rather than cloud cover, which is estimated to be as important as, or likely superior to, the SHF for the surface heat budget during spring.The NCEP-NCAR surface heat flux reanalysis data demonstrate a consistency with the SWE/SCF and air temperature observational data, indicating a good capability for snow-atmosphere interaction analysis.展开更多
Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in ...Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in June in the south of China is discussed.During the flood(drought) events,there exists an anomalous low-frequency anticyclone(cyclone) at the low level of the troposphere over the South China Sea and the northwestern Pacific,accompanied with anomalous low-frequency heat sinks(heat sources),while there exists an anomalous low-frequency cyclone(anticyclone) with anomalous heat sources(sinks) over the area from the south of China to the south of Japan.On average,the phase evolution of the low-frequency in drought events is 7 to 11 days ahead of that in flood events in May to June in the south of China.In flood events,low-frequency heat sources and cyclones are propagated northward from the southern South China Sea,northwestward from the warm pool of the western Pacific and westward from the northwestern Pacific around 140°E,which have very important impact on the abundant rainfall in June in the south of China.However,in drought events,the northward propagations of the low-frequency heat sources and cyclones from the South China Sea and its vicinity are rather late compared with those in flood events,and there is no obvious westward propagation of the heat sources from the northwestern Pacific.The timing of the low-frequency heat source propagation has remarkable impact on the June rainfall in the south of China.展开更多
It is well known that retrieval of parameters is usually ill-posed and highly nonlinear, so parameter retrieval problems are very difficult. There are still many important theoretical issues under research, although g...It is well known that retrieval of parameters is usually ill-posed and highly nonlinear, so parameter retrieval problems are very difficult. There are still many important theoretical issues under research, although great success has been achieved in data assimilation in meteorology and oceanography. This paper reviews the recent research on parameter retrieval, especially that of the authors. First, some concepts and issues of parameter retrieval are introduced and the state-of-the-art parameter retrieval technology in meteorology and oceanography is reviewed briefly, and then atmospheric and oceanic parameters are retrieved using the variational data assimilation method combined with the regularization techniques in four examples： retrieval of the vertical eddy diffusion coefficient; of the turbulivity of the atmospheric boundary layer; of wind from Doppler radar data, and of the physical process parameters. Model parameter retrieval with global and local observations is also introduced.展开更多
Currently, the Chinese central government is considering plans to build a trilateral economic sphere in the Bohai Bay area, including Beijing, Tianjin and Hebei（BTH）, where haze pollution frequently occurs. To achie...Currently, the Chinese central government is considering plans to build a trilateral economic sphere in the Bohai Bay area, including Beijing, Tianjin and Hebei（BTH）, where haze pollution frequently occurs. To achieve sustainable development, it is necessary to understand the physical mechanism of the haze pollution there. Therefore, the pollutant transport mechanisms of a haze event over the BTH region from 23 to 24 September 2011 were studied using the Weather Research and Forecasting model and the FLEXible-PARTicle dispersion model to understand the effects of the local atmospheric circulations and atmospheric boundary layer structure. Results suggested that the penetration by sea-breeze could strengthen the vertical dispersion by lifting up the planetary boundary layer height（PBLH） and carry the local pollutants to the downstream areas; in the early night, two elevated pollution layers（EPLs） may be generated over the mountain areas： the pollutants in the upper EPL at the altitude of 2–2.5 km were favored to disperse by long-range transport, while the lower EPL at the altitude of 1 km may serve as a reservoir, and the pollutants there could be transported downward and contribute to the surface air pollution.The intensity of the sea–land and mountain–valley breeze circulations played an important role in the vertical transport and distribution of pollutants. It was also found that the diurnal evolution of the PBLH is important for the vertical dispersion of the pollutants,which is strongly affected by the local atmospheric circulations and the distribution of urban areas.展开更多
Atmospheric instability information derived from satellites plays an important role in short-term weather forecasting, especially the forecasting of severe convective storms. For the next generation of weather satelli...Atmospheric instability information derived from satellites plays an important role in short-term weather forecasting, especially the forecasting of severe convective storms. For the next generation of weather satellites for Korea＇s multi-purpose geostationary satellite program, a new imaging instrument has been developed. Although this imaging instrument is not de- signed to perform full sounding missions and its capability is limited, its multi-spectral infrared channels provide information on vertical sounding. To take full advantage of the observation data from the much improved spatiotemporal resolution of the imager, the feasibility of an artificial neural network approach for the derivation of the atmospheric instability is investigated. The multi-layer perceptron model with a feed-forward and back-propagation training algorithm shows quite a sensitive re- sponse to the selection of the training dataset and model architecture. Through an extensive performance test with a carefully selected training dataset of 7197 independent profiles, the model architectures are selected to be 12, 5000, and 0.3 for the number of hidden nodes, number of epochs, and learning rate, respectively. The selected model gives a mean absolute error, RMSE, and correlation coefficient of 330 J kg-1, 420 J kg-1, and 0.9, respectively. The feasibility is further demonstrated via application of the model to real observation data from a similar instrument that has comparable observation channels with the planned imager.展开更多
An empirical atmospheric model(EAM) based on the singular value decomposition(SVD) method is evaluated using the composite El Ni(?)o/Southern Oscillation(ENSO) patterns of sea surface temperature (SST) and wind anomal...An empirical atmospheric model(EAM) based on the singular value decomposition(SVD) method is evaluated using the composite El Ni(?)o/Southern Oscillation(ENSO) patterns of sea surface temperature (SST) and wind anomalies as the target scenario.Two versions of the SVD-based EAM were presented for comparisons.The first version estimates the wind anomalies in response to SST variations based on modes that were calculated from a pair of global wind and SST fields(i.e.,conventional EAM or CEAM).The second version utilizes the same model design but is based on modes that were calculated in a region-wise manner by separating the tropical domain from the remaining extratropical regions(i.e.,region-wise EAM or REAM). Our study shows that,while CEAM has shown successful model performance over some tropical areas, such as the equatorial eastern Pacific(EEP),the western North Pacific(WNP),and the tropical Indian Ocean(TIO),its performance over the North Pacific(NP) seems poor.When REAM is used to estimate the wind anomalies instead of CEAM,a marked improvement over NP readily emerges.Analyses of coupled modes indicate that such an improvement can be attributed to a much stronger coupled variability captured by the first region-wise SVD mode at higher latitudes compared with that captured by the conventional one. The newly proposed way of constructing the EAM(i.e.,REAM) can be very useful in the coupled studies because it gives the model a wider application beyond the commonly accepted tropical domain.展开更多
In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inl...In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inland regions. However, few studies on the atmospheric particle were conducted in coastal port areas in China, which indeed suffers atmospheric particle pollution. Lack of the physicochemical characteristics of fine particles serves as an obstacle toward the accurate control for air pollution in the coastal port area in China. Here, a field observation was conducted in an important coastal port city in Yangtze River Delta from March 6 to March 19, 2019. The average PM2.5 concentration was 63.7 ±27.8 μg/m^3 and NO3^-, SO4^2-, NH4^+, and organic matter accounted for ?60% of PM 2.5. Fe was the most abundant trace metal element and V as the ship emission indicator was detected. Transmission electron microscopy images showed that SK-rich, soot, Fe, SK-soot and SK-Fe were the major individual particles in the coastal port. V and soluble Fe were detected in sulfate coating of SK-Fe particles. We found that anthropogenic emissions, marine sea salt, and secondary atmosphere process were the major sources of fine particles. Backward trajectory analysis indicated that the dominant air masses were marine air mass, inland air mass from northern Zhejiang and inland-marine mixed air mass from Shandong and Shanghai during the sampling period. The findings can help us better understand the physicochemical properties of atmospheric fine particles in the coastal port of Eastern China.展开更多
Based on SARS epidemic data and the corresponding atmospheric data, we used the timescale-partitioning technique, spectrum analysis and correlation analysis to investigate the impacts of the atmospheric environmental ...Based on SARS epidemic data and the corresponding atmospheric data, we used the timescale-partitioning technique, spectrum analysis and correlation analysis to investigate the impacts of the atmospheric environmental factors on the SARS epidemic. Results showed that there were close relations between environmental factors and SARS: The daily probable cases of SARS varied in 3-5 day cycles, much the same as the atmospheric elements did. The variations of the epidemics correlated remarkably with atmospheric elements. So conclusions can be drawn that weather changes have influences on the variations of daily SARS cases. In addition, statistical results showed that cold air activities aggravated the SARS epidemic.展开更多
Numerical experiments on forcing dissipation and heating response of dipole (unipole) are carried out using global spectral models with quasi-geostrophic barotropic vorticity equations. For each experiment model integ...Numerical experiments on forcing dissipation and heating response of dipole (unipole) are carried out using global spectral models with quasi-geostrophic barotropic vorticity equations. For each experiment model integration is run for 90 days on the condition of three-wave quasi-resonance. The results are given as follows: Under the effects of dipole (unipole) forcing source and basic flow intensity, there exist strong interactions among the three planetary waves and quasi-biweekly and intraseasonal oscillation of the three planetary waves. In the meantime, the changes in the intensity of dipole or unipole forcing source and basic flow have different frequency modulation effects on LFO in the middle and higher latitudes. The results of the stream function field of three quasi-resonant waves evolving with time confirm that the low-frequency oscillation exists in extratropical latitude.展开更多
Future projection of diffusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health.Here,the diffusion conditions and thei...Future projection of diffusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health.Here,the diffusion conditions and their changes under future warming scenarios are examined.The relative strength of haze events in the Northern China Plain region increase from 150%during 2006–15 to 190%during 2090–99 under RCP8.5 scenarios,induced by a stronger and longer-lasting anticyclone anomaly in eastern China.The strengthened anticyclone anomaly is mainly induced by increased northern wave train convergence emanating from the Barents–Kara Sea,and the longer duration of the anticyclone anomaly is mainly induced by stronger local feedback that can extract more energy from the basic state to maintain the anticyclone anomaly in eastern China.Aerosol reduction is found to play a dominant role in strengthening the upstream wave train near the Barents–Kara Sea and the downstream anticyclone in eastern China,while the effects from increased greenhouse gases are small.The results of this study indicate that future aerosol emissions reduction can induce deteriorating diffusion conditions,suggesting more stringent regulations on aerosol emissions in China are needed to meet air quality standards.展开更多
基金supported by Zhejiang Province Science Fund for Distinguished Young Scholars(No.LR24D050001)the Joint Funds of Zhejiang Provincial Natural Science Foundation of China(No.LZJMZ23D050002)+3 种基金the National Natural Science Foundation of China(No.42175116)the Scientific Research Foundation for Guilin University of Technology(No.GUTQDJJ2023046)supported by Guangxi Engineering Research Center of Comprehensive Treatment for Agricultural Non-Point Source Pollutionthe Modern Industry College of Ecology and Environmental Protection,Guilin University of Technology.
文摘PM_(2.5) and black carbon(BC)are important air pollutants impacting radiation balance,air quality,health,and ecosystems.Ozone(O_(3))levels are increasing despite decreases in other pollutants,posing a challenge for pollution control,especially in coastal cities like Zhoushan,where the monsoonal climate can exacerbate PM_(2.5) and ozone pollution.This study conducted continuous online measurements of major atmospheric pollutants in Zhoushan,Zhejiang Province,in 2020.The results indicate that the highest contribution from local air masses in Zhoushan is observed in spring,accounting for 17.7%,while the greatest average contribution from northern Zhejiang Province,Jiangsu Province,and Shanghai occurs in winter,at 18.5%.Pollutant concentrationswere seasonally variable,with PM_(2.5),BC,and sulfur dioxide concentrations 56.6%,36%,and 58.2%higher in the cold season compared to the warm season.The O_(3) in spring is approximately 50%higher than that in summer.Ship emissions significantly contributed to BC,nitrogen oxides(NO_(x)),and carbon monoxide in Zhoushan.In spring,PM_(2.5) sources included photochemical processes and northern air mass transport,while in winter,PM_(2.5) was due to regional transport.The inhibitory effect of PM_(2.5) on O_(3) formation in the Zhoushan area is relatively weak.Reducing NO_(x) emissions may increase O_(3),emphasizing the need for volatile organic compounds monitoring and regional control measures to improve air quality and ensure sustainable development in Zhoushan.
基金supported by the National Natural Science Foundation of China(Grant No.U2342208)support from NSF/Climate Dynamics Award#2025057。
文摘Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives of billions who depend on or are affected by monsoons, as it is essential for the water cycle, food security, ecology, disaster prevention, and the economy of monsoon regions. Given the extensive literature on Asian monsoon climate prediction, we limit our focus to reviewing the seasonal prediction and predictability of the Asian Summer Monsoon (ASM). However, much of this review is also relevant to monsoon predictions in other seasons and regions. Over the past two decades, considerable progress has been made in the seasonal forecasting of the ASM, driven by an enhanced understanding of the sources of predictability and the dynamics of seasonal variability, along with advanced development in sophisticated models and technologies. This review centers on advances in understanding the physical foundation for monsoon climate prediction (section 2), significant findings and insights into the primary and regional sources of predictability arising from feedback processes among various climate components (sections 3 and 4), the effects of global warming and external forcings on predictability (section 5), developments in seasonal prediction models and techniques (section 6), the challenges and limitations of monsoon climate prediction (section 7), and emerging research trends with suggestions for future directions (section 8). We hope this review will stimulate creative activities to enhance monsoon climate prediction.
基金This work was supported by the National Key Program for Developing Basic Research （Grant No. 2004CB418303）the National Natural Science Foundation of China （Grant No. 40175018）.
文摘The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant （scarce） rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong （weak） heat sources over the eastern Tibetan Plateau, while the abundant （scarce） rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak （strong） heat sources over the tropical western Pacific.
基金supported jointly by the National Natural Science Foundation of China (40975039)the National Basic Research Program of China (2006CB403602 and 2009BAC51B04)
文摘Using two datasets of global pentad grid precipitation and global 850 hPa geopotential height during 1979-2007,this study identified global monsoon troughs and global atmospheric centers of action (ACAs) on a pentad scale.The global monsoon troughs consist of planetary-scale monsoon troughs and peninsula-scale monsoon troughs.Forced by seasonal variations in solar radiation,the inter-tropical convergence zones (ITCZs) represent the planetary-scale monsoon troughs,which are active and shift over the tropical North Pacific,the tropical North Atlantic,and the tropical South Indian oceans.The peninsula-scale monsoon troughs are originated from regional land-sea topography and varied with contrasts in seasonal land-sea surface temperatures and precipitation.During the boreal summer,five peninsula-scale troughs and one planetary-scale trough are distributed in the Asia-Northwest Pacific (NWP) region.In total,22 troughs,nine monsoon troughs,and 19 ACAs in the lower troposphere were identified.Relevant ACAs may be useful in constructing regional monsoon and circulation indices.
基金supported by the National Science Council (Grant No. NSC 98-2745-M-002-011-ASP)the National Basic Research Program "973" (Grant No. 2010CB950401, 2012CB955204)+1 种基金the research foundation of NUIST, the National Natural Science Foundation of China (Grant No. 41005047)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘The aim of the present study was to identify multi-decadal variability （MDV） relative to the current centennial global warming trend in available observation data.The centennial global wanning trend was first identified in the global mean surface temperature （STgm） data.The MDV was identified based on three sets of climate variables,including sea surface temperature （SST）,ocean temperature from the surface to 700 m,and the NCEP and ERA40 reanalysis datasets,respectively.All variables were detrended and low-pass filtered.Through three independent EOF analyses of the filtered variables,all results consistently showed two dominant modes,with their respective temporal variability resembling the Pacific Decadal Oscillation/Inter-decadal Pacific Oscillation （PDO/IPO） and the Atlantic Multi-decadal Oscillation （AMO）.The spatial structure of the PDO-like oscillation is characterized by an ENSO-like structure and hemispheric symmetric features.The structure associated with the AMO-like oscillation exhibits hemispheric asymmetric features with anomalous warm air over Eurasia and warm SST in the Atlantic and Pacific basin north of 10°S,and cold SST over the southern oceans.The Pacific and Atlantic MDV in upper-ocean temperature suggest that they are mutually linked.We also found that the PDO-like and AMO-like oscillations are almost equally important in global-scale MDV by EOF analyses.In the period 1975-2005,the evolution of the two oscillations has given rise to strong temperature trends and has contributed almost half of the STgm warming.Hereon,in the next decade,the two oscillations are expected to slow down the global warming trends.
文摘Paleoclimate simulations usually require model runs over a very long time. The fast integration version of a state-of-the-art general circulation model （GCM）, which shares the same physical and dynamical processes but with reduced horizontal resolution and increased time step, is usually developed. In this study, we configure a fast version of an atmospheric GCM （AGCM）, the Grid Atmospheric Model of IAP/LASG （Institute of Atmospheric Physics/State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics）, at low resolution （GAMIL-L, hereafter）, and compare the simulation results with the NCEP/NCAR reanalysis and other data to examine its performance. GAMIL-L, which is derived from the original GAMIL, is a finite difference AGCM with 72 × 40 grids in longitude and latitude and 26 vertical levels. To validate the simulated climatology and variability, two runs were achieved. One was a 60-year control run with fixed climatological monthly sea surface temperature （SST） forcing, and the other was a 50-yr （1950-2000） integration with observational time-varying monthly SST forcing. Comparisons between these two cases and the reanalysis, including intra-seasonal and inter-annual variability are also presented. In addition, the differences between GAMIL-L and the original version of GAMIL are also investigated.The results show that GAMIL-L can capture most of the large-scale dynamical features of the atmosphere, especially in the tropics and mid latitudes, although a few deficiencies exist, such as the underestimated Hadley cell and thereby the weak strength of the Asia summer monsoon. However, the simulated mean states over high latitudes, especially over the polar regions, are not acceptable. Apart from dynamics, the thermodynamic features mainly depend upon the physical parameterization schemes. Since the physical package of GAMIL-L is exactly the same as the original high-resolution version of GAMIL, in which the NCAR Community Atmosphere Model （CAM2） physical package was used, there are only small differences between them in the precipitation and temperature fields. Because our goal is to develop a fast-running AGCM and employ it in the coupled climate system model of IAP/LASG for paleoclimate studies such as ENSO and Australia-Asia monsoon, particular attention has been paid to the model performances in the tropics. More model validations, such as those ran for the Southern Oscillation and South Asia monsoon, indicate that GAMIL-L is reasonably competent and valuable in this regard.
基金supported by the National Natural Science Foundation of China (Grant No.40275004)the State Key Laboratory of Atmosphere Physics and Chemistry,and the City University of Hong Kong(Grant No.8780046)the City University of Hong Kong Strategic Research(Grant No.7001038)
文摘This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.
基金This research was supported by the Navy MURI Grant N00014-01-1-0850the 973 Proiect No,2001CB309400.
文摘The physical retrieval algorithm of atmospheric temperature and moisture distribution from the Atmospheric InfraRed Sounder （AIRS） radiances is presented. The retrieval algorithm is applied to AIRS clear-sky radiance measurements. The algorithm employs a statistical retrieval followed by a subsequent nonlinear physical retrieval. The regression coefficients for the statistical retrieval are derived from a dataset of global radiosonde observations （RAOBs） comprising atmospheric temperature, moisture, and ozone profiles. Evaluation of the retrieved profiles is performed by a comparison with RAOBs from the Atmospheric Radiation Measurement （ARM） Program Cloud And Radiation Testbed （CART） in Oklahoma, U. S. A.. Comparisons show that the physically-based AIRS retrievals agree with the RAOBs from the ARM CART site with a Root Mean Square Error （RMSE） of 1K on average for temperature profiles above 850 hPa, and approximately 10% on average for relative humidity profiles. With its improved spectral resolution, AIRS depicts more detailed structure than the current Geostationary Operational Environmental Satellite （GOES） sounder when comparing AIRS sounding retrievals with the operational GOES sounding products.
基金supported by the National Natural Science Foundation of China(Grant Nos. 40633018 and 40675036)
文摘NCEP/NCAR reanalysis data and a 47-year precipitation dataset are utilized to analyze the relationship between an atmospheric heat source （hereafter called 〈 Q1 〉） over the Qinghai-Xizang Plateau （QXP） and its surrounding area and precipitation in northwest China. Our main conclusions are as follows： （1） The horizontal distribution of 〈 Q1 〉 and its changing trend are dramatic over QXP in the summer. There are three strong centers of 〈 Q1 〉 over the south side of QXP with obvious differences in the amount of yearly precipitation and the number of heat sinks predominate in the arid and semi-arid regions of northwest China （NWC）, beside the northern QXP with an obvious higher intensity in years with less precipitation. （2） In the summer, the variation of the heat source＇s vertical structure is obviously different between greater and lesser precipitation years in eastern northwest China （ENWC）. The narrow heat sink belt forms between the northeast QXP and the southwestern part of Lake Baikal. In July and August of greater precipitation years, the heating center of the eastern QXP stays nearly over 35°N, and at 400 hPa of the eastern QXP, the strong upward motion of the heating center constructs a closed secondary vertical circulation cell over the northeast QXP （40~ 46~N）, which is propitious to add precipitation over the ENWC. Otherwise, the heating center shifts to the south of 30°N and disappears in July and August of lesser precipitation years, an opposite secondary circulation cell forms over the northeast QXP, which is a disadvantage for precipitation. Meanwhile, the secondary circulation cell in years with more or less precipitation over the ENWC is also related to the heat source over the Lake Baikal. （3） The vertical structure of the heat source over the western QXP has obvious differences between greater and lesser precipitation years in western northwest China in June and July. The strong/weak heat source over the western QXP produces relatively strong/weak ascending motion and correspondingly constructs a secondary circulation cell in lesser/greater precipitation years.
基金National Natural Science Foundation of China(40645026)National Basic Research Programof China (2002CB410801)
文摘Based on the geographical circumstance, climate and the boundary layer meteorology features of the Pearl River Delta, a boundary layer concept model of the Pearl River Delta was built. The concept model consists of four fundamental factors that affect the boundary layer meteorology of the Pearl River Delta and can convincingly explain the reason of the air quality change in the Pearl River Delta. The model can be used to the diffusion capability analysis, the air pollution potential forecasting or haze forecasting, etc.
基金supported by the National Natural Science Foundation of China[grant numbers 4142100441210007]+1 种基金the Chinese Academy of Sciences(CAS)-Peking University(PKU)Partnership Programthe Atmosphere-Ocean Research Center(AORC)and International Pacific Research Center(IPRC)at University of Hawaii
文摘This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent （SWE）, snow cover frequency （SCF）, and 500 hPa geopotential height data. It is found that the Eurasian SWE/SCF and circulation dominant modes are stably coupled from autumn to the subsequent spring.The temporal coherence of the seasonal evolution of the dominant modes is examined.The seasonal evolution of the Eurasian circulation and SWE dominant modes exhibit good coherence, whereas the evolution of the Eurasian SCF dominant mode is incoherent during the autumn-winter transition season. This incoherence is associated with a sign-change in the SCF anomalies in Europe during the autumn-winter transition season, which is related to the wind anomalies over Europe. In addition, the surface heat budget associated with the Eurasian SWE/SCF and circulation dominant modes is analyzed. The sensible heat flux （SHF） related to the wind-induced thermal advection dominates the surface heat budget from autumn to the subsequent spring, with the largest effect during winter. The surface net shortwave radiation is mainly modulated by snow cover rather than cloud cover, which is estimated to be as important as, or likely superior to, the SHF for the surface heat budget during spring.The NCEP-NCAR surface heat flux reanalysis data demonstrate a consistency with the SWE/SCF and air temperature observational data, indicating a good capability for snow-atmosphere interaction analysis.
基金National Key Program for Developing Basic Research (2009CB421404)Key Program of National Science Foundation of China (40730951)Program of National Science Foundation of China(40605028)
文摘Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in June in the south of China is discussed.During the flood(drought) events,there exists an anomalous low-frequency anticyclone(cyclone) at the low level of the troposphere over the South China Sea and the northwestern Pacific,accompanied with anomalous low-frequency heat sinks(heat sources),while there exists an anomalous low-frequency cyclone(anticyclone) with anomalous heat sources(sinks) over the area from the south of China to the south of Japan.On average,the phase evolution of the low-frequency in drought events is 7 to 11 days ahead of that in flood events in May to June in the south of China.In flood events,low-frequency heat sources and cyclones are propagated northward from the southern South China Sea,northwestward from the warm pool of the western Pacific and westward from the northwestern Pacific around 140°E,which have very important impact on the abundant rainfall in June in the south of China.However,in drought events,the northward propagations of the low-frequency heat sources and cyclones from the South China Sea and its vicinity are rather late compared with those in flood events,and there is no obvious westward propagation of the heat sources from the northwestern Pacific.The timing of the low-frequency heat source propagation has remarkable impact on the June rainfall in the south of China.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 90411006）by the Shanghai Science and Technology Association （Grant No. 02DJ14032）.
文摘It is well known that retrieval of parameters is usually ill-posed and highly nonlinear, so parameter retrieval problems are very difficult. There are still many important theoretical issues under research, although great success has been achieved in data assimilation in meteorology and oceanography. This paper reviews the recent research on parameter retrieval, especially that of the authors. First, some concepts and issues of parameter retrieval are introduced and the state-of-the-art parameter retrieval technology in meteorology and oceanography is reviewed briefly, and then atmospheric and oceanic parameters are retrieved using the variational data assimilation method combined with the regularization techniques in four examples： retrieval of the vertical eddy diffusion coefficient; of the turbulivity of the atmospheric boundary layer; of wind from Doppler radar data, and of the physical process parameters. Model parameter retrieval with global and local observations is also introduced.
基金supported by the National Natural Science Foundation of China (No. 41175004)the China Meteorological Administration Special Public Welfare Research Fund (No. GYHY201106033)
文摘Currently, the Chinese central government is considering plans to build a trilateral economic sphere in the Bohai Bay area, including Beijing, Tianjin and Hebei（BTH）, where haze pollution frequently occurs. To achieve sustainable development, it is necessary to understand the physical mechanism of the haze pollution there. Therefore, the pollutant transport mechanisms of a haze event over the BTH region from 23 to 24 September 2011 were studied using the Weather Research and Forecasting model and the FLEXible-PARTicle dispersion model to understand the effects of the local atmospheric circulations and atmospheric boundary layer structure. Results suggested that the penetration by sea-breeze could strengthen the vertical dispersion by lifting up the planetary boundary layer height（PBLH） and carry the local pollutants to the downstream areas; in the early night, two elevated pollution layers（EPLs） may be generated over the mountain areas： the pollutants in the upper EPL at the altitude of 2–2.5 km were favored to disperse by long-range transport, while the lower EPL at the altitude of 1 km may serve as a reservoir, and the pollutants there could be transported downward and contribute to the surface air pollution.The intensity of the sea–land and mountain–valley breeze circulations played an important role in the vertical transport and distribution of pollutants. It was also found that the diurnal evolution of the PBLH is important for the vertical dispersion of the pollutants,which is strongly affected by the local atmospheric circulations and the distribution of urban areas.
基金supported by the National Meteorological Satellite Center(NMSC) of the Korea Meteorological Administration,entitled "Development of Geostationary Meteorological Ground Segment"
文摘Atmospheric instability information derived from satellites plays an important role in short-term weather forecasting, especially the forecasting of severe convective storms. For the next generation of weather satellites for Korea＇s multi-purpose geostationary satellite program, a new imaging instrument has been developed. Although this imaging instrument is not de- signed to perform full sounding missions and its capability is limited, its multi-spectral infrared channels provide information on vertical sounding. To take full advantage of the observation data from the much improved spatiotemporal resolution of the imager, the feasibility of an artificial neural network approach for the derivation of the atmospheric instability is investigated. The multi-layer perceptron model with a feed-forward and back-propagation training algorithm shows quite a sensitive re- sponse to the selection of the training dataset and model architecture. Through an extensive performance test with a carefully selected training dataset of 7197 independent profiles, the model architectures are selected to be 12, 5000, and 0.3 for the number of hidden nodes, number of epochs, and learning rate, respectively. The selected model gives a mean absolute error, RMSE, and correlation coefficient of 330 J kg-1, 420 J kg-1, and 0.9, respectively. The feasibility is further demonstrated via application of the model to real observation data from a similar instrument that has comparable observation channels with the planned imager.
文摘An empirical atmospheric model(EAM) based on the singular value decomposition(SVD) method is evaluated using the composite El Ni(?)o/Southern Oscillation(ENSO) patterns of sea surface temperature (SST) and wind anomalies as the target scenario.Two versions of the SVD-based EAM were presented for comparisons.The first version estimates the wind anomalies in response to SST variations based on modes that were calculated from a pair of global wind and SST fields(i.e.,conventional EAM or CEAM).The second version utilizes the same model design but is based on modes that were calculated in a region-wise manner by separating the tropical domain from the remaining extratropical regions(i.e.,region-wise EAM or REAM). Our study shows that,while CEAM has shown successful model performance over some tropical areas, such as the equatorial eastern Pacific(EEP),the western North Pacific(WNP),and the tropical Indian Ocean(TIO),its performance over the North Pacific(NP) seems poor.When REAM is used to estimate the wind anomalies instead of CEAM,a marked improvement over NP readily emerges.Analyses of coupled modes indicate that such an improvement can be attributed to a much stronger coupled variability captured by the first region-wise SVD mode at higher latitudes compared with that captured by the conventional one. The newly proposed way of constructing the EAM(i.e.,REAM) can be very useful in the coupled studies because it gives the model a wider application beyond the commonly accepted tropical domain.
基金supported by the National Natural Science Foundation of China (Nos. 41805099,91844301)the China Postdoctoral Science Foundation (No. 2018M632449)the Zhejiang Provincial Natural Science Foundation of China (No. LZ19D050001)。
文摘In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inland regions. However, few studies on the atmospheric particle were conducted in coastal port areas in China, which indeed suffers atmospheric particle pollution. Lack of the physicochemical characteristics of fine particles serves as an obstacle toward the accurate control for air pollution in the coastal port area in China. Here, a field observation was conducted in an important coastal port city in Yangtze River Delta from March 6 to March 19, 2019. The average PM2.5 concentration was 63.7 ±27.8 μg/m^3 and NO3^-, SO4^2-, NH4^+, and organic matter accounted for ?60% of PM 2.5. Fe was the most abundant trace metal element and V as the ship emission indicator was detected. Transmission electron microscopy images showed that SK-rich, soot, Fe, SK-soot and SK-Fe were the major individual particles in the coastal port. V and soluble Fe were detected in sulfate coating of SK-Fe particles. We found that anthropogenic emissions, marine sea salt, and secondary atmosphere process were the major sources of fine particles. Backward trajectory analysis indicated that the dominant air masses were marine air mass, inland air mass from northern Zhejiang and inland-marine mixed air mass from Shandong and Shanghai during the sampling period. The findings can help us better understand the physicochemical properties of atmospheric fine particles in the coastal port of Eastern China.
基金Scientific and development foundation of Guangdong Meteorological Observatory
文摘Based on SARS epidemic data and the corresponding atmospheric data, we used the timescale-partitioning technique, spectrum analysis and correlation analysis to investigate the impacts of the atmospheric environmental factors on the SARS epidemic. Results showed that there were close relations between environmental factors and SARS: The daily probable cases of SARS varied in 3-5 day cycles, much the same as the atmospheric elements did. The variations of the epidemics correlated remarkably with atmospheric elements. So conclusions can be drawn that weather changes have influences on the variations of daily SARS cases. In addition, statistical results showed that cold air activities aggravated the SARS epidemic.
基金Natural Science Foundation of China (40275016)Operation "Six Kinds of Talents Summit"Foundation for Jiangsu Province
文摘Numerical experiments on forcing dissipation and heating response of dipole (unipole) are carried out using global spectral models with quasi-geostrophic barotropic vorticity equations. For each experiment model integration is run for 90 days on the condition of three-wave quasi-resonance. The results are given as follows: Under the effects of dipole (unipole) forcing source and basic flow intensity, there exist strong interactions among the three planetary waves and quasi-biweekly and intraseasonal oscillation of the three planetary waves. In the meantime, the changes in the intensity of dipole or unipole forcing source and basic flow have different frequency modulation effects on LFO in the middle and higher latitudes. The results of the stream function field of three quasi-resonant waves evolving with time confirm that the low-frequency oscillation exists in extratropical latitude.
基金Minghuai WANG is supported by the National Natural Science Foundation of China[grant numbers 91744208,41925023,41575073,and 41621005]the Ministry of Science and Technology of China[grant numbers 2017YFA0604002 and 2016YFC0200503]+1 种基金Yang ZHANG is supported by the National Natural Science Foundation of China[grant number 41675055]This research was also supported by the Collaborative Innovation Center of Climate Change,Jiangsu Province.
文摘Future projection of diffusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health.Here,the diffusion conditions and their changes under future warming scenarios are examined.The relative strength of haze events in the Northern China Plain region increase from 150%during 2006–15 to 190%during 2090–99 under RCP8.5 scenarios,induced by a stronger and longer-lasting anticyclone anomaly in eastern China.The strengthened anticyclone anomaly is mainly induced by increased northern wave train convergence emanating from the Barents–Kara Sea,and the longer duration of the anticyclone anomaly is mainly induced by stronger local feedback that can extract more energy from the basic state to maintain the anticyclone anomaly in eastern China.Aerosol reduction is found to play a dominant role in strengthening the upstream wave train near the Barents–Kara Sea and the downstream anticyclone in eastern China,while the effects from increased greenhouse gases are small.The results of this study indicate that future aerosol emissions reduction can induce deteriorating diffusion conditions,suggesting more stringent regulations on aerosol emissions in China are needed to meet air quality standards.
