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Evaluation of multidecadal and longer-term temperature changes since 850 CE based on northern hemisphere proxy-based reconstructions and model simulations

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Science China Earth Sciences 2020年第8期63卷 1126-1143页

作者： Jianglin WANG Bao YANG Jingyun ZHENG Xuezhen ZHANG Zhiyuan WANG Miao FANG Feng SHI Jingjing LIU Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100049China College of Geography and Environmental Science Zhejiang Normal UniversityJinhua 321004China Northwest Institute of Eco-Environment and Resource Chinese Academy of SciencesLanzhou 730000China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044China

The temperature variability over multidecadal and longer timescales(e.g., the cold epochs in the late 15 th, 17 th, and early 19 th centuries) is significant and dominant in the millennium-long, large-scale reconstructions and model simulations;however, their temporal patterns in the reconstructed and simulated temperature series are not well understood and require a detailed assessment and comparison. Here, we compare the reconstructed and simulated temperature series for the northern hemisphere(NH) at multidecadal and longer-term timescales(>30 years) by evaluating their covariance, climate sensitivity and amplitude of temperature changes. We found that covariances between different reconstructions or between reconstructions and simulations are generally high for the whole period of 850–1999 CE, due to their similar long-term temporal patterns. However,covariances between different reconstructions or between reconstructions and simulations steadily decline as time series extends further back in time, becoming particularly small during Medieval times. This is related to the large uncetainties in the reconstructions caused by the decreased number of proxy records and sample duplication during the pre-instrumental *** based solely on tree-ring data show higher skill than multiproxy reconstructions in capturing the amplitude of volcanic cooling simulated by models. Meanwhile, climate models have a shorter recovery(i.e., lag) in response to the cooling caused by volcanic eruptions and solar activity minima, implying the lack of some important feedback mechanisms between external forcing and internal climate processes in climate models. Amplitudes of temperature variations in the latest published tree-ring reconstructions are comparable to those of the multiproxy reconstructions. We found that the temperature difference between the Medieval Climate Anomaly(950–1250 CE) and the Little Ice Age(1450–1850 CE) is generally larger in proxybased reconstruct

关键词： Temperature changes Multidecadal and longer-term variability northern hemisphere Last millennium

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A Preliminary Study on the Relationship Between Arctic Oscillation and Daily SLP Variance in the northern hemisphere During Wintertime

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Advances in Atmospheric Sciences 2005年第3期22卷 313-327页

作者：龚道溢 Helge DRANGE Key Laboratory of Environmental Change and Natural DisasterCollege of Resources Science and Technology Beijing Normal University Beijing 100875 Bjerknes Centre for Climate Research/Nansen Environmental and Remote Sensing CenterUniversity of Bergen Norway

In the present study, the authors investigated the relationship between the Arctic Oscillation (AO) and the high-frequency variability of daily sea level pressures in the northern hemisphere in winter (November through March), using NCEP/NCAR reanalysis datasets for the time period of 1948/49-2000/01. High-frequency signals are defined as those with timescales shorter than three weeks and measured in terms of variance, for each winter for each grid. The correlations between monthly mean AO index and high-frequency variance are conducted. A predominant feature is that several regional centers with high correlation show up in the middle to high latitudes. Significant areas include mid- to high-latitude Asia centered at Siberia, northern Europe and the middle-latitude North Atlantic east of northern Africa. Their strong correlations can also be confirmed by the singular value decomposition analysis of covariance between mean SLP and high-frequency variance. This indicates that the relationship of AO with daily Sea Level Pressure (SLP) is confined to some specific regions in association with the inherent atmospheric dynamics. In middle-latitude Asia, there is a significant (at the 95% level) trend of variance of-2.26% (10 yr)-1. Another region that displays a strong trend is the northwestern Pacific with a significant rate of change of 0.80% (10 yr)-1. If the winter of 1948/49, an apparent outlier, is excluded, a steady linear trend of +1.51% (10 yr)-1 shows up in northern Europe. The variance probability density functions (PDFs) are found to change in association with different AO phases. The changes corresponding to high and low AO phases, however, are asymmetric in these regions. Some regions such as northern Europe display much stronger changes in high AO years, whereas some other regions such as Siberia show a stronger connection to low AO conditions. These features are supported by ECMWF reanalysis data. However, the dynamical mechanisms involved in the AO-high fr

关键词： Arctic Oscillation sea level pressure (SLP) northern hemisphere synoptic variance

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Machine learning-based predictions of current and future susceptibility to retrogressive thaw slumps across the northern hemisphere

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Advances in Climate Change Research 2024年第2期15卷 253-264页

作者： Jing LUO Guo-An YIN Fu-Jun NIU Tian-Chun DONG Ze-Yong GAO Ming-Hao LIU Fan YU State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China China Railway Qinghai-Tibet Group Co. LtdXining 810000China University of Chinese Academy of Sciences Beijing 100049China

Retrogressive thaw slumps(RTSs)caused by the thawing of ground ice on permafrost slopes have dramatically increased and become a common permafrost hazard across the northern hemisphere during previous ***,a gap remains in our comprehensive understanding of the spatial controlling factors,including the climate and terrain,that are conducive to these RTSs at a global *** machine learning methodologies,we mapped the current and future RTSs susceptibility distributions by incorporating a range of environmental factors and RTSs *** identified freezing-degree days and maximum summer rainfall as the primary environmental factors affecting RTSs *** final ensemble susceptibility map suggests that regions with high to very high susceptibility could constitute(11.6±0.78)%of the northern hemisphere's permafrost *** juxtaposed with the current(2000-2020)RTSs susceptibility map,the total area with high to very high susceptibility could witness an increase ranging from(31.7±0.65)%(SSP585)to(51.9±0.73)%(SSP126)by the *** insights gleaned from this study not only offer valuable implications for engineering applications across the northern hemisphere,but also provide a long-term insight into the potential change of RTSs in permafrost regions in response to climate change.

关键词： Retrogressive thaw slump Machine learning Susceptibility map Permafrost northern hemisphere

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Temperate northern hemisphere dominates the global soil CH_(4) sink

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Journal of Mountain Science 2022年第11期19卷 3051-3062页

作者： XU Xin WEI Da QI Ya-hui WANG Xiao-dan Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China

Methane(CH_(4)) is the second largest longlived greenhouse gas after the CO_(2), which contributes 20% of global warming forcing. Global aerated soils remove CH_(4) from the troposphere, but the quantification of its magnitude and spatial variability is still of a large uncertainty. This study collected 1240records of the CH_(4) uptake by soils across the *** estimates update the global soil CH_(4) sink to 31.9+/-0.16 Tg CH_(4) a^(-1), 42% higher than the previous inventory-based estimation, with 56% from temperate regions. Also, our dataset revealed that the global drylands dominated the soil CH_(4) sink, which is different from traditional forest-dominated *** the past four decades, the soil porosity affected by soil moisture controls the variation in the uptake in the tropics, while warming temperatures benefit methanotrophs in temperate and boreal soils,especially the drylands, where the soil porosity is not limiting. Our simulations indicate that the CH_(4) uptake will increase by 11%–31% by the end of the 21st century, much lower than the previous *** study substantially constrains the global soil CH_(4) sink estimates and reveals the warming temperate northern hemisphere is a dominant CH_(4) uptake region in the past and future, while the uptake decreases in tropical soils under increasing precipitation.

关键词： Climate change Methane uptake northern hemisphere Observations Simulations

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The Role of the Solar Cycle in the Relationship Between the North Atlantic Oscillation and northern hemisphere Surface Temperatures

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Advances in Atmospheric Sciences 2007年第2期24卷 191-198页

作者： Laura DE LA TORRE Luis GIMENO Juan Antonio AEL Raquel NIETO Universidad de Vigo Facultad de Ciencias de Ourense 32004OurenseSpain

The North Atlantic Oscillation （NAO） is one of the leading modes of climate variability in the northern hemisphere. It has been shown that it clearly relates to changes in meteorological variables, such as surface temperature, at hemispherical scales. However, recent studies have revealed that the NAO spatial pattern also depends upon solar forcing. Therefore, its effects on meteorological variables must vary depending upon this factor. Moreover, it could be that the Sun affects climate through variability patterns, a hypothesis that is the focus of this study. We find that the relationship between the NAO/AO and hemispheric temperature varies depending upon solar activity. The results show a positive significant correlation only when solar activity is high. Also, the results support the idea that solar activity influences tropospheric climate fluctuations in the northern hemisphere via the fluctuations of the stratospheric polar vortex .

关键词： solar activity North Atlantic Oscillation Arctic Oscillation northern hemisphere surface temperature

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A long-term daily gridded snow depth dataset for the northern hemisphere from 1980 to 2019 based on machine learning

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Big Earth Data 2024年第2期8卷 274-301页

作者： Yanxing Hu Tao Che Liyun Dai Yu Zhu Lin Xiao Jie Deng Xin Li Key Laboratory of Remote Sensing of Gansu Province Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina State Key Laboratory of Tibetan Plateau Earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijingChina Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security Institute of International Rivers and Eco-SecurityYunnan UniversityKunmingChina National Forestry and Grassland Administration Key Laboratory of Forest Resource Conservation and Ecological Safety on the Upper Reaches of the Yangtze River Sichuan Province Key Laboratory of Ecological Forestry Engineering on the Upper Reaches of the Yangtze RiverCollege of ForestrySichuan Agricultural UniversityChengduChina

A high-quality snow depth product is very import for cryospheric science and its related *** long time-series snow depth products covering the northern hemisphere can be divided into two categories:remote sensing snow depth products and reana-lysis snow depth ***,existing gridded snow depth products have some *** sensing-derived snow depth products are temporally and spatially discontinuous and tend to underestimate snow depth,while reanalysis snow depth products have coarse spatial resolutions and great *** overcome these problems,in our previous work we proposed a novel data fusion framework based on Random Forest Regression of snow products from Advanced Microwave Scanning Radiometer for the Earth Observing System(AMSR-E),Advanced Microwave Scanning Radiometer-2(AMSR2),Global Snow Monitoring for Climate Research(GlobSnow),the northern hemisphere Snow Depth(NHSD),ERA-Interim,and Modern-Era Retrospective Analysis for Research and Applications,ver-sion 2(MERRA-2),incorporating geolocation(latitude and longitude),and topographic data(elevation),which were used as input indepen-dent *** than 30,000 ground observation sites were used as the dependent variable to train and validate the model in different time *** fusion framework resulted in a long time series of continuous daily snow depth product over the northern hemisphere with a spatial resolution of 0.25°.Here,we compared the fused snow depth and the original gridded snow depth products with 13,272 observation sites,showing an improved precision of our *** evaluation indices of the fused(best original)dataset yielded a coeffi-cient of determination R2 of 0.81(0.23),Root Mean Squared Error(RMSE)of 7.69(15.86)cm,and Mean Absolute Error(MAE)of 2.74(6.14)*** of the bias(88.31%)between the fused snow depth and in situ observations was in the range of−5 cm to 5 *** accuracy assessment of independent snow observation sites-Sodank

关键词： Snow depth datasets machine learning data fusion northern hemisphere

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A 38-Year Climatology of Explosive Cyclones over the northern hemisphere

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Advances in Atmospheric Sciences 2020年第2期37卷 143-159页

作者： Gang FU Yawen SUN Jilin SUN Pengyuan LI Department of Marine Meteorology Ocean−Atmosphere Interaction and Climate LaboratoryKey Laboratory of Physical OceanographyOcean University of ChinaQingdao 266100China Division of Oceanic Dynamics and Climate Qingdao National Laboratory for Marine Science and TechnologyQingdao 266100China North China Sea Marine Forecasting Center Qingdao 266100China Shandong Provincial Key Laboratory of Marine Ecological Environment and Disaster Prevention and Mitigation Qingdao 266100China

Explosive cyclones(ECs)over two basins in the northern hemisphere(20°-90°N)from January 1979 to December2016 are investigated using ERA-Interim and Optimum Interpolation Sea Surface Temperature(OISST)*** classical definition of an EC is modified considering not only the rapid drop of the central sea level pressure of the cyclone,but also the strong wind speed at the height of 10 m in which maximum wind speeds greater than 17.2 m s^-1are *** to the locations of the northern Atlantic and northern Pacific,the whole northern hemisphere is divided into the"A region"(20°-90°N,90°W-90°E)and"P region"(20°-90°N,90°E-90°W).Over both the A and P regions,the climatological features of ECs,such as their spatial distribution,intensity,seasonal variation,interannual variation,and moving tracks,are documented.

关键词： explosive cyclone Atlantic basin Pacific basin northern hemisphere annual climatology seasonal climatology spatial distribution moving track

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Simulated effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region of the northern hemisphere

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Research in Cold and Arid Regions 2021年第1期13卷 18-29页

作者： Di Ma SiQiong Luo DongLin Guo ShiHua Lyu XianHong Meng BoLi Chen LiHui Luo Key Laboratory for Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of ScienceLanzhouGansu 730000China College of Atmospheric Sciences Lanzhou UniversityLanzhouGansu 730000China Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengduSichuan 610225China Changzhou Meteorological Bureau ChangzhouJiangsu 213000China State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

Soil freeze-thaw process is closely related to surface energy budget,hydrological activity,and terrestrial *** this study,two numerical experiments(including and excluding soil freeze-thaw process)were designed to examine the effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region in the northern hemisphere based on the state-of-the-art Community Earth System Model version *** show that in response to soil freeze-thaw process,the area averaged soil temperature in the shallow layer(0.0175−0.0451 m)decreases by 0.35℃in the TP(Tibetan Plateau),0.69℃in CES(Central and Eastern Siberia),and 0.6℃in NA(North America)during summer,and increases by 1.93℃in the TP,2.28℃in CES and 1.61℃in NA during winter,***,in response to soil freeze-thaw process,the area averaged soil liquid water content increases in summer and decrease in *** surface heat flux components,the ground heat flux is most significantly affected by the freeze-thaw process in both summer and winter,followed by sensible heat flux and latent heat flux in *** the TP area,the ground heat flux increases by 2.82 W/m2(28.5%)in summer and decreases by 3.63 W/m2(40%)in ***,in CES,the ground heat flux increases by 1.89 W/m2(11.3%)in summer and decreases by 1.41 W/m2(18.6%)in *** heat fluxes in the Tibetan Plateau are more susceptible to the freeze-thaw process compared with the high-latitude frozen soil *** freeze-thaw process can induce significant warming in the Tibetan Plateau in ***,this process induces significant cooling in high-latitude regions in *** frozen ground can prevent soil liquid water from infiltrating to deep soil layers at the beginning of thawing;however,as the frozen ground thaws continuously,the infiltration of the liquid water increases and the deep soil can store water like a sponge,accompanied by decreasing surface *** influence of the soil freeze-thaw pr

关键词： freeze-thaw effect hydrologic and thermal frozen ground northern hemisphere

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A lake ice phenology dataset for the northern hemisphere based on passive microwave remote sensing

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Big Earth Data 2022年第4期6卷 401-419页

作者： Xingxing Wang Yubao Qiu Yixiao Zhang Juha Lemmetyinen Bin Cheng Wenshan Liang Matti Leppäranta College of Urban and Environment Sciences Northwest UniversityXi’anChina Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina International Research Center of Big Data for Sustainable Development Goals BeijingChina FMI-AIR Joint Research Center for Arctic Observations Finnish Meteorological Institute and Aerospace Information Research InstituteChinese Academy of SciencesSodankyläFinland Arctic Space Center Finnish Meteorological InstituteHelsinkiFinland Finnish Meteorological Institute HelsinkiFinland Institute of Atmospheric and Earth Sciences University of HelsinkiHelsinkiFinland

Lake ice phenology(LIP)is an essential indicator of climate change and helps with understanding of the regional characteristics of climate change *** observation records and remote sensing retrieval products of lake ice phenology are abundant for Europe,North America,and the Tibetan Plateau,but there is a lack of data for inner *** this work,enhanced-resolution passive microwave satellite data(PMW)were used to investigate the northern hemisphere Lake Ice Phenology(PMW LIP).The Freeze Onset(FO),Complete Ice Cover(CIC),Melt Onset(MO),and Complete Ice Free(CIF)dates were derived for 753 lakes,including 409 lakes for which ice phenology retrievals were available for the period 1978 to 2020 and 344 lakes for which these were available for 2002 to *** of the PMW LIP using ground records gave correlation coefficients of 0.93 and 0.84 for CIC and CIF,respectively,and the corresponding values of the RMSE were 11.84 and 10.07 *** lake ice phenology in this dataset was significantly correlated(Pnorthern *** dataset is available at http://***/10.11922/sciencedb.j00076.00081.

关键词： Lake ice phenology dataset northern hemisphere passive microwave remote sensing

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The state and fate of lake ice thickness in the northern hemisphere

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Science Bulletin 2022年第5期67卷 537-546,M0004页

作者： Xingdong Li Di Long Qi Huang Fanyu Zhao State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China

Lake ice thickness(LIT)is important for regional hydroclimate systems,lake ecosystems,and human activities on the ice,and is thought to be highly susceptible to global ***,the spatiotemporal variability in LIT is largely unknown due to the difficulty in deriving in situ measurements and the lack of an effective remote sensing *** intensive development and applications of lake ice models driven by general circulation model output,evaluation of the global LIT is mostly based on assumed“ideal”lakes in each grid cell of the climate forcing data.A method for calculating the actual global LIT is therefore urgently *** we use satellite altimetry to retrieve ice thickness for 16 large lakes in the northern hemisphere(Lake Baikal,Great Slave Lake,and others)with an accuracy of~0.2 m for almost three *** then develop a 1-D lake ice model driven primarily by remotely sensed data and cross-validated with the altimetric LIT to provide a robust means of estimating LIT for lakes larger than 50 km^(2)across the northern *** LIT(annual maximum ice thickness)for 1313 simulated lakes and reservoirs covering~840,000 km^(2)for 2003–2018 is 0.63±0.02 m,corresponding to~485 Gt of *** changes are projected for 2071–2099 under RCPs 2.6,6.0,and 8.5,showing that the mean LIT could decrease by~0.35 m under the worst concentration pathway and the associated lower ice road availability could have a significant impact on socio-economic activities.

关键词： Lake ice thickness Satellite altimetry Lake ice modeling northern hemisphere Climate change

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