An extreme （weather and climate） event does not only mean that an extreme occurs at a location, but more generally it can impact a certainarea and last a certain period of time, which is defined as a regional extrem...An extreme （weather and climate） event does not only mean that an extreme occurs at a location, but more generally it can impact a certainarea and last a certain period of time, which is defined as a regional extreme event （REE） with a certain impacted area and duration. The conceptof REE has been defined to allow mainly objective assessment of the events without a pre-determined boundary and duration. This paper reviewsthe studies on REEs published during the past 20 years, especially recent years. Mainly in view of methodology, these studies can be divided intothree types studies focusing on spatial simultaneity, studies focusing on temporal persistence, and studies identifying REEs. The methodsidentifying REEs include two kinds, e.g., type-I methods stressing REE＇s temporal persistence within a relatively certain area and type-IImethods focusing on catching a complete REE. Identification methods proposed in this paper could provide valuable information for variouspurposes, such as real-time monitoring, estimating long-term changes, mechanism diagnosis, forecasting study and even attribution analysis.Research on REEs is important for objectively defining extreme weather and climate events, which depends on the spatial and temporal scales ofinterest. Such an objective definition will support ongoing climate monitoring and improve the assessment of how regional extreme events havechanged over time.展开更多
中国覆盖比较完整的台站观测始于1951年，1951年之前虽然有一些观测记录，但是残缺不全。所以要建立更长的气候序列就要吸收代用资料，但是代用资料可能与气候要素仅有一定程度的相关，不可能一一对应，因此应用代用资料重建的气候序列...中国覆盖比较完整的台站观测始于1951年，1951年之前虽然有一些观测记录，但是残缺不全。所以要建立更长的气候序列就要吸收代用资料，但是代用资料可能与气候要素仅有一定程度的相关，不可能一一对应，因此应用代用资料重建的气候序列有一定的不确定性。英国East Anglia大学的Climatic Research Unit（简称CRU）通过整合已有的若干个知名数据库，重建了一套覆盖完整、高分辨率、且无缺测的月平均地表气候要素数据集，时间范围覆盖1901-2003年，空间为0．5°×0．5°经纬网格覆盖所有陆地。这套资料和中国已有的气候数据相比具有如下优点：第一，中国西部20世纪前半期非常缺少观测，CRU资料尽管包含插值带来的误差，经比较仍可作为有一定信度的参考；第二，中国现有的百年温度序列只是年或季分辨率，而CRU资料达到月分辨率；第三，建立这个序列仅使用观测结果，做统计内插，不包括代用资料所带来的不确定性。因此，CRU的序列与用代用资料补充得到的序列在资料方面有较大不同，比较这两个序列，不仅可以进一步确认中国气候变化的特征，也可以彼此校正。结果表明：（1）CRU资料反映的全国年平均温度年际变化和考虑代用资料重建的序列吻合得很好，相关系数达到0．84；（2）区域尺度上，两者在10个典型分区的气温变率也相当一致，相关整体保持在0．8左右，仅新疆西南部和西藏西北部两者差异较大；（3）CRU资料揭示的中国年总降水量在1951～2000年的变化与160站观测吻合，相关系数达到0．93；（4）CRU资料的中国东部四季降水量和重建资料十分一致，秋季一致性最好，相关0．93；（5）CRU资料和重建的序列比较一致地表现出中国温度和降水年代际变化的主要特征，其给出的20世纪20年代中国大旱和20世纪40年代中国高温的空间分布与作者过去的结论相一致。这表明，作者过去重建的中国气候序列有比较大的可靠性，而CRU资料也提供了新的信息，特别是在20世纪前半期和中国西部。展开更多
A wavelet method was applied to detect inhomogeneities in daily meteorological series, data which are being increasingly applied in studies of climate extremes. The wavelet method has been applied to a few well- estab...A wavelet method was applied to detect inhomogeneities in daily meteorological series, data which are being increasingly applied in studies of climate extremes. The wavelet method has been applied to a few well- established long-term daily temperature series back to the 18th century, which have been ＂homogenized＂ with conventional approaches. Various types of problems remaining in the series were revealed with the wavelet method. Their influences on analyses of change in climate extremes are discussed. The results have importance for understanding issues in conventional climate data processing and for development of improved methods of homogenization in order to improve analysis of climate extremes based on daily data.展开更多
The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that pro...The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered. These issues are discussed in the order of their importance for temperature records at these spatial scales： biases in SST data, particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time.展开更多
Based on C-LSAT2.0,using high-and low-frequency components reconstruction methods,combined with observation constraint masking,a reconstructed C-LSAT2.0 with 756 ensemble members from the 1850s to 2018 has been develo...Based on C-LSAT2.0,using high-and low-frequency components reconstruction methods,combined with observation constraint masking,a reconstructed C-LSAT2.0 with 756 ensemble members from the 1850s to 2018 has been developed.These ensemble versions have been merged with the ERSSTv5 ensemble dataset,and an upgraded version of the CMSTInterim dataset with 5°×5°resolution has been developed.The CMST-Interim dataset has significantly improved the coverage rate of global surface temperature data.After reconstruction,the data coverage before 1950 increased from 78%−81%of the original CMST to 81%−89%.The total coverage after 1955 reached about 93%,including more than 98%in the Northern Hemisphere and 81%−89%in the Southern Hemisphere.Through the reconstruction ensemble experiments with different parameters,a good basis is provided for more systematic uncertainty assessment of C-LSAT2.0 and CMSTInterim.In comparison with the original CMST,the global mean surface temperatures are estimated to be cooler in the second half of 19th century and warmer during the 21st century,which shows that the global warming trend is further amplified.The global warming trends are updated from 0.085±0.004℃(10 yr)^(–1)and 0.128±0.006℃(10 yr)^(–1)to 0.089±0.004℃(10 yr)^(–1)and 0.137±0.007℃(10 yr)^(–1),respectively,since the start and the second half of 20th century.展开更多
A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneitie...A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneities remained in the dataset. The present study produces a further-adjusted and updated dataset based on the Multiple Analysis of Series for Homogenization （MASH） method. The MASH procedure detects 33 monthly temperature records as erroneous outliers and 152 meaningful break points in the monthly SAT series since 1924 at 28 stations. The inhomogeneous parts are then adjusted relative to the latest homogeneous part of the series. The new data show significant warming trends during 1924-2016 at all the stations, ranging from 0.48 to 3.57℃ （100 yr）^-1, with a regional mean trend of 1.65℃ （100 yr）^-1 ; whereas, the previous results ranged from a slight cooling at two stations to considerable warming, up to 4.5℃ （100 yr）^-1. It is suggested that the further-adjusted data are a better representation of the large-scale pattern of climate change in the region for the past century. The new data axe available online at http：//www.dx.doi.org/10.11922/sciencedb.516.展开更多
It is well-known that global warming due to anthropogenic atmospheric greenhouse effects advanced the start of the vegetation growing season （SOS） across the globe during the 20th century. Projections of further cha...It is well-known that global warming due to anthropogenic atmospheric greenhouse effects advanced the start of the vegetation growing season （SOS） across the globe during the 20th century. Projections of further changes in the SOS for the 21st century under certain emissions scenarios （Representative Concentration Pathways, RCPs） are useful for improving understanding of the consequences of global warming. In this study, we first evaluate a linear relationship between the SOS （defined using the normalized difference vegetation index） and the April temperature for most land areas of the Northern Hemisphere for 1982-2008. Based on this relationship and the ensemble projection of April temperature under RCPs from the latest state-of-the-art global coupled climate models, we show the possible changes in the SOS for most of the land areas of the Northern Hemisphere during the 21st century. By around 2040-59, the SOS will have advanced by -4.7 days under RCP2.6, -8.4 days under RCP4.5, and -10.1 days under RCPS.5, relative to 1985-2004. By 2080-99, it will have advanced by -4.3 days under RCP2.6, -11.3 days under RCP4.5, and -21.6 days under RCP8.5. The geographic pattern of SOS advance is considerably dependent on that of the temperature sensitivity of the SOS. The larger the temperature sensitivity, the larger the date-shift-rate of the SOS.展开更多
Background:Increasing the use of forest harvest residues for bioenergy production reduces greenhouse emissions from the use of fossil fuels.However,it may also reduce carbon stocks and habitats for deadwood dependent ...Background:Increasing the use of forest harvest residues for bioenergy production reduces greenhouse emissions from the use of fossil fuels.However,it may also reduce carbon stocks and habitats for deadwood dependent species.Consequently,simple tools for assessing the trade-offs of alternative management practices on forest dynamics and their services to people are needed.The objectives of this study were to combine mapping and simulation modelling to investigate the effects of forest management on ecosystem services related to carbon cycle in the case of bioenergy production;and to evaluate the suitability of this approach for assessing ecosystem services at the landscape level.Stand level simulations of forest growth and carbon budget were combined with extensive multi-source forest inventory data across a southern boreal landscape in Finland.Stochastic changes in the stand age class distribution over the study region were simulated to mimic variation in management regimes.Results:The mapping framework produced reasonable estimates of the effects of forest management on a set of key ecosystem service indicators:the annual carbon stocks and fluxes of forest biomass and soil,timber and energy-wood production and the coarse woody litter production over a simulation period 2012–2100.Regular harvesting,affecting the stand age class distribution,was a key driver of the carbon stock changes at a landscape level.Extracting forest harvest residues in the final felling caused carbon loss from litter and soil,particularly with combined aboveground residue and stump harvesting.It also reduced the annual coarse woody litter production,demonstrating negative impacts on deadwood abundance and,consequently,forest biodiversity.Conclusions:The refined mapping framework was suitable for assessing ecosystem services at the landscape level.The procedure contributes to bridging the gap between ecosystem service mapping and detailed simulation modelling in boreal forests.It allows for visualizing ecosystem services as fine resolution maps to support sustainable land use planning.In the future,more detailed models and a wider variety of ecosystem service indicators could be added to develop the method.展开更多
1. IntroductionHistoric instrumental weather observations, made on land or at sea from as early as the 17th century （e.g.,Camuffo et al.,2010）,are integral to extending our understanding of the decadal and centennia...1. IntroductionHistoric instrumental weather observations, made on land or at sea from as early as the 17th century （e.g.,Camuffo et al.,2010）,are integral to extending our understanding of the decadal and centennial variations of Earth＇s climate and for comparison with paleo-proxy data.展开更多
Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can g...Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can greatly promote understanding of spatiotemporal variations in air pollution in China.To do this,AOD(550 nm)values from 2000 to 2014 were obtained from the Coupled Model Intercomparison Project(CIMP6),the second version of Modern-Era Retrospective analysis for Research,and Applications(MERRA-2),and the Moderate Resolution Imaging Spectroradiometer(MODIS;flying on the Terra satellite)combined Dark Target and Deep Blue(DTB)aerosol product.We used the TerraMODIS DTB AOD(hereafter MODIS DTB AOD)as a standard to evaluate CMIP6 Ensemble AOD(hereafter CMIP6 AOD)and MERRA-2 reanalysis AOD(hereafter MERRA-2 AOD).Results show better correlations and smaller errors between MERRA-2 and MODIS DTB AOD,than between CMIP6 and MODIS DTB AOD,in most regions of China,at both annual and seasonal scales.However,significant under-and over-estimations in the MERRA-2 and CMIP6 AOD were also observed relative to MODIS DTB AOD.The long-term(2000-2014)MODIS DTB AOD distributions show the highest AOD over the North China Plain(0.71)followed by Central China(0.69),Yangtse River Delta(0.67),Sichuan Basin(0.64),and Pearl River Delta(0.54)regions.The lowest AOD values were recorded over the Tibetan Plateau(0.13±0.01)followed by Qinghai(0.19±0.03)and the Gobi Desert(0.21±0.03).Large amounts of sand and dust particles emitted from natural sources(the Taklamakan and Gobi Deserts)may result in higher AOD in spring compared to summer,autumn,and winter.Trends were also calculated for 2000-2005,for2006-2010(when China introduced strict air pollution control policies during the 11 th Five Year Plan or FYP),and for 2011-2014(during the 12 th FYP).An increasing trend in MODIS DTB AOD was observed throughout the country during 2000-2014.The uncontrolled industrialization,urbanization,and rapid economic development that mostly occurred from 2000 to 2005 probably contributed to the overall increase in AOD.Finally,China’s air pollution control policies helped to reduce AOD in most regions of the country;this was more evident during the 12 th FYP period(2011-2014)than during the 11 th FYP period(2006-2010).Therefore this study strongly advises the authority to retain or extend these policies in the future for improving air quality.展开更多
Emphasis on future environmental changes grows due to climate change,with simulations predicting rising river temperatures globally.For Poland,which has a long history of thermal studies of rivers,such an approach has...Emphasis on future environmental changes grows due to climate change,with simulations predicting rising river temperatures globally.For Poland,which has a long history of thermal studies of rivers,such an approach has not been implemented to date.This study used 9 Global Climate Models and tested three machine-learning techniques to predict river temperature changes.Random Forest performed best,with R^(2)=0.88 and lowest error(RMSE:2.25,MAE:1.72).The range of future water temperature changes by the end of the 21st century was based on the Shared Socioeconomic Pathway scenarios SSP2-4.5 and SSP5-8.5.It was determined that by the end of the 21st century,the average temperature will increase by 2.1°C(SSP2-4.5)and 3.7°C(SSP5-8.5).A more detailed analysis,divided by two major basins Vistula and Odra,covered about 90%of Poland's territory.The average temperature increase,according to scenarios SSP2-4.5 and SSP5-8.5 for the Odra basin rivers,is 1.6°C and 3.2°C and for the Vistula basin rivers 2.3°C and 3.8°C,respectively.The Vistula basin's higher warming is due to less groundwater input and continental climate influence.These findings provide a crucial basis for water management to mitigate warming effects in Poland.展开更多
We integrated Enviro-HIRLAM(Environment-High Resolution Limited Area Model)meteorological output into FLEXPART(FLEXible PARTicle dispersion model).A FLEXPART simulation requires meteorological input from a numerical w...We integrated Enviro-HIRLAM(Environment-High Resolution Limited Area Model)meteorological output into FLEXPART(FLEXible PARTicle dispersion model).A FLEXPART simulation requires meteorological input from a numerical weather prediction(NWP)model.The publicly available version of FLEXPART can utilize either ECMWF(European Centre for Medium-range Weather Forecasts)Integrated Forecast System(IFS)forecast or reanalysis NWP data,or NCEP(U.S.National Center for Environmental Prediction)Global Forecast System(GFS)forecast or reanalysis NWP data.The primary benefits of using Enviro-HIRLAM are that it runs at a higher resolution and accounts for aerosol effects in meteorological fields.We compared backward trajectories gener-ated with FLEXPART using Enviro-HIRLAM(both with and without aerosol effects)to trajectories generated using NCEP GFS and ECMWF IFS meteorological inputs,for a case study of a heavy haze event which occurred in Beijing,China in November 2018.We found that results from FLEXPART were considerably different when using different meteorological inputs.When aerosol effects were included in the NWP,there was a small but noticeable differ-ence in calculated trajectories.Moreover,when looking at potential emission sensitivity instead of simply expressing trajectories as lines,additional information,which may have been missed when looking only at trajectories as lines,can be inferred.展开更多
We have used the China Homogenized Historic Temperature dataset and some long-term station series of the neighbor countries from CRUTEM3,a 5°×5° gridded dataset of monthly mean temperature since 1900,to...We have used the China Homogenized Historic Temperature dataset and some long-term station series of the neighbor countries from CRUTEM3,a 5°×5° gridded dataset of monthly mean temperature since 1900,to provide a 107-year record of surface temperature trends and variability.We derived a comprehensive set of uncertainty estimates to accompany the data:measurement and sampling errors,uncertainties in temperature bias estimates,and uncertainties arising from limited observational coverage on large-scale averages have all been estimated.We reanalysed the temperature changes during the period of record.The best estimates of trends for 1900-2006 with uncertainties at 95% confidence range are about 0.09±0.017°C/decade for the year as a whole,and 0.14±0.021°C/decade,0.11±0.021°C/decade,0.04±0.017°C/decade,and 0.07±0.017°C/decade for winter,spring,summer and autumn respectively.For 1954-2006,the trends for annual,winter,spring,summer and autumn are:0.26±0.032°C/decade,0.35±0.046°C/decade,0.25±0.051°C/decade,0.16±0.037°C/decade and 0.22±0.055°C/decade.Winter saw the most significant warming trend in both 1900-2006 and 1954-2006,while during the most recent period(the satellite era,1979-2006),all the seasons show similar warming trends:0.45±0.13°C/decade,0.51±0.11°C/decade,0.52±0.16°C/decade,0.37±0.10°C/decade and 0.50±0.16°C/decade for annual,winter,spring,summer and autumn.Trends arising from urbanization have been evaluated as less than 5% of the total warming trend for 1951-2001,so this bias was not removed.展开更多
Global mean surface temperature(GMST)is one of the most important large-scale indicators for characterizing climate change on Earth,and Surface Temperature(ST)is also the most accurate key climate element currently un...Global mean surface temperature(GMST)is one of the most important large-scale indicators for characterizing climate change on Earth,and Surface Temperature(ST)is also the most accurate key climate element currently understood by scientists and the public.Even so,there have been extensive discussions about the accuracy of global(regional)surface temperature(air temperature)changes[lj.From the perspective of climatic data acquisition and data reliability,the current GMST series and the evaluation of global warming rates are all based on several observation-based datasets produced by combining anomalies of Land Surface Air Temperatures(LSAT)and Sea Surface Temperatures(SST).展开更多
In an attempt to clearly separate the volcanic signal,we use a mixture of principal component analysis(PCA)and superposed epoch analysis to identify volcanic signal in the global surface tem- perature field.In this wa...In an attempt to clearly separate the volcanic signal,we use a mixture of principal component analysis(PCA)and superposed epoch analysis to identify volcanic signal in the global surface tem- perature field.In this way,the spatial and temporal pattern of volcanic signals is identified in the global surface temperature records.Our results show that the strongest ENSO and volcanic signals are related with the first and the third principal components respectively.Both ENSO and volcanic signals have responses in the second principal component.展开更多
文摘An extreme （weather and climate） event does not only mean that an extreme occurs at a location, but more generally it can impact a certainarea and last a certain period of time, which is defined as a regional extreme event （REE） with a certain impacted area and duration. The conceptof REE has been defined to allow mainly objective assessment of the events without a pre-determined boundary and duration. This paper reviewsthe studies on REEs published during the past 20 years, especially recent years. Mainly in view of methodology, these studies can be divided intothree types studies focusing on spatial simultaneity, studies focusing on temporal persistence, and studies identifying REEs. The methodsidentifying REEs include two kinds, e.g., type-I methods stressing REE＇s temporal persistence within a relatively certain area and type-IImethods focusing on catching a complete REE. Identification methods proposed in this paper could provide valuable information for variouspurposes, such as real-time monitoring, estimating long-term changes, mechanism diagnosis, forecasting study and even attribution analysis.Research on REEs is important for objectively defining extreme weather and climate events, which depends on the spatial and temporal scales ofinterest. Such an objective definition will support ongoing climate monitoring and improve the assessment of how regional extreme events havechanged over time.
文摘中国覆盖比较完整的台站观测始于1951年，1951年之前虽然有一些观测记录，但是残缺不全。所以要建立更长的气候序列就要吸收代用资料，但是代用资料可能与气候要素仅有一定程度的相关，不可能一一对应，因此应用代用资料重建的气候序列有一定的不确定性。英国East Anglia大学的Climatic Research Unit（简称CRU）通过整合已有的若干个知名数据库，重建了一套覆盖完整、高分辨率、且无缺测的月平均地表气候要素数据集，时间范围覆盖1901-2003年，空间为0．5°×0．5°经纬网格覆盖所有陆地。这套资料和中国已有的气候数据相比具有如下优点：第一，中国西部20世纪前半期非常缺少观测，CRU资料尽管包含插值带来的误差，经比较仍可作为有一定信度的参考；第二，中国现有的百年温度序列只是年或季分辨率，而CRU资料达到月分辨率；第三，建立这个序列仅使用观测结果，做统计内插，不包括代用资料所带来的不确定性。因此，CRU的序列与用代用资料补充得到的序列在资料方面有较大不同，比较这两个序列，不仅可以进一步确认中国气候变化的特征，也可以彼此校正。结果表明：（1）CRU资料反映的全国年平均温度年际变化和考虑代用资料重建的序列吻合得很好，相关系数达到0．84；（2）区域尺度上，两者在10个典型分区的气温变率也相当一致，相关整体保持在0．8左右，仅新疆西南部和西藏西北部两者差异较大；（3）CRU资料揭示的中国年总降水量在1951～2000年的变化与160站观测吻合，相关系数达到0．93；（4）CRU资料的中国东部四季降水量和重建资料十分一致，秋季一致性最好，相关0．93；（5）CRU资料和重建的序列比较一致地表现出中国温度和降水年代际变化的主要特征，其给出的20世纪20年代中国大旱和20世纪40年代中国高温的空间分布与作者过去的结论相一致。这表明，作者过去重建的中国气候序列有比较大的可靠性，而CRU资料也提供了新的信息，特别是在20世纪前半期和中国西部。
文摘A wavelet method was applied to detect inhomogeneities in daily meteorological series, data which are being increasingly applied in studies of climate extremes. The wavelet method has been applied to a few well- established long-term daily temperature series back to the 18th century, which have been ＂homogenized＂ with conventional approaches. Various types of problems remaining in the series were revealed with the wavelet method. Their influences on analyses of change in climate extremes are discussed. The results have importance for understanding issues in conventional climate data processing and for development of improved methods of homogenization in order to improve analysis of climate extremes based on daily data.
文摘The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered. These issues are discussed in the order of their importance for temperature records at these spatial scales： biases in SST data, particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time.
文摘Based on C-LSAT2.0,using high-and low-frequency components reconstruction methods,combined with observation constraint masking,a reconstructed C-LSAT2.0 with 756 ensemble members from the 1850s to 2018 has been developed.These ensemble versions have been merged with the ERSSTv5 ensemble dataset,and an upgraded version of the CMSTInterim dataset with 5°×5°resolution has been developed.The CMST-Interim dataset has significantly improved the coverage rate of global surface temperature data.After reconstruction,the data coverage before 1950 increased from 78%−81%of the original CMST to 81%−89%.The total coverage after 1955 reached about 93%,including more than 98%in the Northern Hemisphere and 81%−89%in the Southern Hemisphere.Through the reconstruction ensemble experiments with different parameters,a good basis is provided for more systematic uncertainty assessment of C-LSAT2.0 and CMSTInterim.In comparison with the original CMST,the global mean surface temperatures are estimated to be cooler in the second half of 19th century and warmer during the 21st century,which shows that the global warming trend is further amplified.The global warming trends are updated from 0.085±0.004℃(10 yr)^(–1)and 0.128±0.006℃(10 yr)^(–1)to 0.089±0.004℃(10 yr)^(–1)and 0.137±0.007℃(10 yr)^(–1),respectively,since the start and the second half of 20th century.
基金supported by the Chinese Academy of Sciences International Collaboration Program(Grant No.134111KYSB20160010)the National Natural Science Foundation of China(Grant Nos.41505071 and 41475078)the UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP) China as part of the Newton Fund
文摘A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneities remained in the dataset. The present study produces a further-adjusted and updated dataset based on the Multiple Analysis of Series for Homogenization （MASH） method. The MASH procedure detects 33 monthly temperature records as erroneous outliers and 152 meaningful break points in the monthly SAT series since 1924 at 28 stations. The inhomogeneous parts are then adjusted relative to the latest homogeneous part of the series. The new data show significant warming trends during 1924-2016 at all the stations, ranging from 0.48 to 3.57℃ （100 yr）^-1, with a regional mean trend of 1.65℃ （100 yr）^-1 ; whereas, the previous results ranged from a slight cooling at two stations to considerable warming, up to 4.5℃ （100 yr）^-1. It is suggested that the further-adjusted data are a better representation of the large-scale pattern of climate change in the region for the past century. The new data axe available online at http：//www.dx.doi.org/10.11922/sciencedb.516.
基金supported by the CAS Strategic Priority Research Program-Climate Change: Carbon Budget and Relevant Issues (Grant No. XDA05090000)City U Strategic Research (Grant No. 7004164)the National Natural Science Foundation of China (Project No. 41405082)
文摘It is well-known that global warming due to anthropogenic atmospheric greenhouse effects advanced the start of the vegetation growing season （SOS） across the globe during the 20th century. Projections of further changes in the SOS for the 21st century under certain emissions scenarios （Representative Concentration Pathways, RCPs） are useful for improving understanding of the consequences of global warming. In this study, we first evaluate a linear relationship between the SOS （defined using the normalized difference vegetation index） and the April temperature for most land areas of the Northern Hemisphere for 1982-2008. Based on this relationship and the ensemble projection of April temperature under RCPs from the latest state-of-the-art global coupled climate models, we show the possible changes in the SOS for most of the land areas of the Northern Hemisphere during the 21st century. By around 2040-59, the SOS will have advanced by -4.7 days under RCP2.6, -8.4 days under RCP4.5, and -10.1 days under RCPS.5, relative to 1985-2004. By 2080-99, it will have advanced by -4.3 days under RCP2.6, -11.3 days under RCP4.5, and -21.6 days under RCP8.5. The geographic pattern of SOS advance is considerably dependent on that of the temperature sensitivity of the SOS. The larger the temperature sensitivity, the larger the date-shift-rate of the SOS.
基金supported by Maj and Tor Nessling Foundation through the grant “Coupling carbon sequestration of forests and croplands with ecosystem service assessments”(decision No. 201700251)LIFE+financial instrument of the European Union (LIFE12 ENV/FI/000409, MONIMET)+1 种基金the Academy of Finland Strategic Research Council project (SRC 2017/312559 IBC-CARBON)supported by the Academy of Finland through the grant “Trade-offs and synergies in land-based climate change mitigation and biodiversity conservation”(decision No. 322066)
文摘Background:Increasing the use of forest harvest residues for bioenergy production reduces greenhouse emissions from the use of fossil fuels.However,it may also reduce carbon stocks and habitats for deadwood dependent species.Consequently,simple tools for assessing the trade-offs of alternative management practices on forest dynamics and their services to people are needed.The objectives of this study were to combine mapping and simulation modelling to investigate the effects of forest management on ecosystem services related to carbon cycle in the case of bioenergy production;and to evaluate the suitability of this approach for assessing ecosystem services at the landscape level.Stand level simulations of forest growth and carbon budget were combined with extensive multi-source forest inventory data across a southern boreal landscape in Finland.Stochastic changes in the stand age class distribution over the study region were simulated to mimic variation in management regimes.Results:The mapping framework produced reasonable estimates of the effects of forest management on a set of key ecosystem service indicators:the annual carbon stocks and fluxes of forest biomass and soil,timber and energy-wood production and the coarse woody litter production over a simulation period 2012–2100.Regular harvesting,affecting the stand age class distribution,was a key driver of the carbon stock changes at a landscape level.Extracting forest harvest residues in the final felling caused carbon loss from litter and soil,particularly with combined aboveground residue and stump harvesting.It also reduced the annual coarse woody litter production,demonstrating negative impacts on deadwood abundance and,consequently,forest biodiversity.Conclusions:The refined mapping framework was suitable for assessing ecosystem services at the landscape level.The procedure contributes to bridging the gap between ecosystem service mapping and detailed simulation modelling in boreal forests.It allows for visualizing ecosystem services as fine resolution maps to support sustainable land use planning.In the future,more detailed models and a wider variety of ecosystem service indicators could be added to develop the method.
基金the ongoing support of CSSP China under the BEIS UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP) China as part of the Newton Fundsupported by funding from the EU Copernicus Climate Change Service(C3S)
文摘1. IntroductionHistoric instrumental weather observations, made on land or at sea from as early as the 17th century （e.g.,Camuffo et al.,2010）,are integral to extending our understanding of the decadal and centennial variations of Earth＇s climate and for comparison with paleo-proxy data.
基金The National Key Research and Development Program of China(2016YFC1400901)Jiangsu Technology Project of Nature Resources(KJXM2019042)+2 种基金the Jiangsu Provincial Department of Education for the Special Project of Jiangsu Distinguished Professor(R2018T22)the National Natural Science Foundation of China(Grant No.41976165)the Startup Foundation for Introduction Talent of NUIST(2017r107)。
文摘Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can greatly promote understanding of spatiotemporal variations in air pollution in China.To do this,AOD(550 nm)values from 2000 to 2014 were obtained from the Coupled Model Intercomparison Project(CIMP6),the second version of Modern-Era Retrospective analysis for Research,and Applications(MERRA-2),and the Moderate Resolution Imaging Spectroradiometer(MODIS;flying on the Terra satellite)combined Dark Target and Deep Blue(DTB)aerosol product.We used the TerraMODIS DTB AOD(hereafter MODIS DTB AOD)as a standard to evaluate CMIP6 Ensemble AOD(hereafter CMIP6 AOD)and MERRA-2 reanalysis AOD(hereafter MERRA-2 AOD).Results show better correlations and smaller errors between MERRA-2 and MODIS DTB AOD,than between CMIP6 and MODIS DTB AOD,in most regions of China,at both annual and seasonal scales.However,significant under-and over-estimations in the MERRA-2 and CMIP6 AOD were also observed relative to MODIS DTB AOD.The long-term(2000-2014)MODIS DTB AOD distributions show the highest AOD over the North China Plain(0.71)followed by Central China(0.69),Yangtse River Delta(0.67),Sichuan Basin(0.64),and Pearl River Delta(0.54)regions.The lowest AOD values were recorded over the Tibetan Plateau(0.13±0.01)followed by Qinghai(0.19±0.03)and the Gobi Desert(0.21±0.03).Large amounts of sand and dust particles emitted from natural sources(the Taklamakan and Gobi Deserts)may result in higher AOD in spring compared to summer,autumn,and winter.Trends were also calculated for 2000-2005,for2006-2010(when China introduced strict air pollution control policies during the 11 th Five Year Plan or FYP),and for 2011-2014(during the 12 th FYP).An increasing trend in MODIS DTB AOD was observed throughout the country during 2000-2014.The uncontrolled industrialization,urbanization,and rapid economic development that mostly occurred from 2000 to 2005 probably contributed to the overall increase in AOD.Finally,China’s air pollution control policies helped to reduce AOD in most regions of the country;this was more evident during the 12 th FYP period(2011-2014)than during the 11 th FYP period(2006-2010).Therefore this study strongly advises the authority to retain or extend these policies in the future for improving air quality.
文摘Emphasis on future environmental changes grows due to climate change,with simulations predicting rising river temperatures globally.For Poland,which has a long history of thermal studies of rivers,such an approach has not been implemented to date.This study used 9 Global Climate Models and tested three machine-learning techniques to predict river temperature changes.Random Forest performed best,with R^(2)=0.88 and lowest error(RMSE:2.25,MAE:1.72).The range of future water temperature changes by the end of the 21st century was based on the Shared Socioeconomic Pathway scenarios SSP2-4.5 and SSP5-8.5.It was determined that by the end of the 21st century,the average temperature will increase by 2.1°C(SSP2-4.5)and 3.7°C(SSP5-8.5).A more detailed analysis,divided by two major basins Vistula and Odra,covered about 90%of Poland's territory.The average temperature increase,according to scenarios SSP2-4.5 and SSP5-8.5 for the Odra basin rivers,is 1.6°C and 3.2°C and for the Vistula basin rivers 2.3°C and 3.8°C,respectively.The Vistula basin's higher warming is due to less groundwater input and continental climate influence.These findings provide a crucial basis for water management to mitigate warming effects in Poland.
基金the Jenny and Antti Wihuri Foundation project,with the grant for“Air pollution cocktail in Gigacity”Funding was also received from the Research Council of Finland(formerly the Academy of Finland,AoF)project 311932 and applied towards this project+1 种基金Partially,funding included contribution from EU Horizon 2020 CRiceS project“Climate relevant interactions and feedbacks:the key role of sea ice and snow in the polar and global climate system”under grant agreement No 101003826and AoF project ACCC“The Atmosphere and Climate Competence Center”under grant agreement No 337549.
文摘We integrated Enviro-HIRLAM(Environment-High Resolution Limited Area Model)meteorological output into FLEXPART(FLEXible PARTicle dispersion model).A FLEXPART simulation requires meteorological input from a numerical weather prediction(NWP)model.The publicly available version of FLEXPART can utilize either ECMWF(European Centre for Medium-range Weather Forecasts)Integrated Forecast System(IFS)forecast or reanalysis NWP data,or NCEP(U.S.National Center for Environmental Prediction)Global Forecast System(GFS)forecast or reanalysis NWP data.The primary benefits of using Enviro-HIRLAM are that it runs at a higher resolution and accounts for aerosol effects in meteorological fields.We compared backward trajectories gener-ated with FLEXPART using Enviro-HIRLAM(both with and without aerosol effects)to trajectories generated using NCEP GFS and ECMWF IFS meteorological inputs,for a case study of a heavy haze event which occurred in Beijing,China in November 2018.We found that results from FLEXPART were considerably different when using different meteorological inputs.When aerosol effects were included in the NWP,there was a small but noticeable differ-ence in calculated trajectories.Moreover,when looking at potential emission sensitivity instead of simply expressing trajectories as lines,additional information,which may have been missed when looking only at trajectories as lines,can be inferred.
基金supported by the Joint DECC and Defra Integrated Climate Programme-GA01101supported by the National Science and Technology Supporting Plan of the Twelfth Five-Year (2007BAC29B01-01)+2 种基金the Ministry of Science and Technology of China through the based-platforms special project of the scientific data sharing system (2005DKA31700-01)the National Natural Science Foundation of China (40605021)China Meteorological Administration Special Foundation for Climate Change (540000G010C01)
文摘We have used the China Homogenized Historic Temperature dataset and some long-term station series of the neighbor countries from CRUTEM3,a 5°×5° gridded dataset of monthly mean temperature since 1900,to provide a 107-year record of surface temperature trends and variability.We derived a comprehensive set of uncertainty estimates to accompany the data:measurement and sampling errors,uncertainties in temperature bias estimates,and uncertainties arising from limited observational coverage on large-scale averages have all been estimated.We reanalysed the temperature changes during the period of record.The best estimates of trends for 1900-2006 with uncertainties at 95% confidence range are about 0.09±0.017°C/decade for the year as a whole,and 0.14±0.021°C/decade,0.11±0.021°C/decade,0.04±0.017°C/decade,and 0.07±0.017°C/decade for winter,spring,summer and autumn respectively.For 1954-2006,the trends for annual,winter,spring,summer and autumn are:0.26±0.032°C/decade,0.35±0.046°C/decade,0.25±0.051°C/decade,0.16±0.037°C/decade and 0.22±0.055°C/decade.Winter saw the most significant warming trend in both 1900-2006 and 1954-2006,while during the most recent period(the satellite era,1979-2006),all the seasons show similar warming trends:0.45±0.13°C/decade,0.51±0.11°C/decade,0.52±0.16°C/decade,0.37±0.10°C/decade and 0.50±0.16°C/decade for annual,winter,spring,summer and autumn.Trends arising from urbanization have been evaluated as less than 5% of the total warming trend for 1951-2001,so this bias was not removed.
基金supported by the National Natural Science Foundation of China (41975105)the National Key Research & Development Program of China (2018YFC1507705 and 2017YFC1502301)。
文摘Global mean surface temperature(GMST)is one of the most important large-scale indicators for characterizing climate change on Earth,and Surface Temperature(ST)is also the most accurate key climate element currently understood by scientists and the public.Even so,there have been extensive discussions about the accuracy of global(regional)surface temperature(air temperature)changes[lj.From the perspective of climatic data acquisition and data reliability,the current GMST series and the evaluation of global warming rates are all based on several observation-based datasets produced by combining anomalies of Land Surface Air Temperatures(LSAT)and Sea Surface Temperatures(SST).
文摘In an attempt to clearly separate the volcanic signal,we use a mixture of principal component analysis(PCA)and superposed epoch analysis to identify volcanic signal in the global surface tem- perature field.In this way,the spatial and temporal pattern of volcanic signals is identified in the global surface temperature records.Our results show that the strongest ENSO and volcanic signals are related with the first and the third principal components respectively.Both ENSO and volcanic signals have responses in the second principal component.
