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Gridded reconstruction of the population in the traditional cultivated region of China from 1776 to 1953

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Science China Earth Sciences 2022年第2期65卷 365-378页

作者： xuezhen zhang Fahao WANG Weidong LU Shicheng LI Jingyun ZHENG Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Faculty of Geographic Sciences Beijing Normal UniversityBeijing 100875China Center for Historical Geographical Studies Fudan UniversityShanghai 200433China Department of Land Resource Management School of Public AdministrationChina University of GeosciencesWuhan 430074China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

Using modern census and environmental factor data,this study first identified the environmental factors that significantly affect the population distribution through Geodetector analysis and then constructed a population spatial distribution model based on the random forest regression ***,with this model and historical population data that were examined and corrected by historians,gridded population distributions with a spatial resolution of 10 km by 10 km in the traditional cultivated region of China(TCRC,hereafter)were reconstructed for six time slices from 1776 to *** the reconstruction dataset,the spatiotemporal characteristics of the population distribution were *** results showed that(1)the environmental factors that significantly affected the population density differences among counties in the TCRC mainly consisted of elevation,slope,relief amplitude,distances to the nearest prefectural and provincial capitals,distance to the nearest river and the climatology moisture index.(2)Using the census data of 1934 counties in the TCRC in 2000 and the abovementioned environmental factor data,a random forest regression algorithm-based population spatial distribution model was *** determination coefficient(R^(2))is *** 88.4%of the counties(districts),the relative errors of the model predictions were less than 50%.(3)From 1776 to 1953,the total population in the study area showed an *** to 1851,the population increased mainly in the Yangtze River *** this period,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 292 to *** 1851 to 1953,the population increased extensively across the study *** the North China Plain and the Pearl River Delta,the number of grid cells in which the population densities were greater than 500 persons per km^(2) increased from 36 to 88 and from 4 to 35,*** spatial clustering pattern of the popula

关键词： Population Traditional cultivated region of China(TCRC) Historical periods Gridded reconstruction

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Rates of temperature change in China during the past 2000 years

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Science China Earth Sciences 2011年第11期54卷 1627-1634页

作者： GE QuanSheng zhang xuezhen HAO ZhiXin ZHENG JingYun Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Using 24 proxy temperature series, the rates of temperature change in China are analyzed at the 30- to 100-year scales for the past 2000 years and at the 10-year scale for the past 500 years. The results show that, at the 100-year scale, the warming rate for the whole of China in the 20th century was only 0.6±1.6℃/100 a （interval at the 95% confidence level, which is used here- after）, while the peak warming rate for the period from the Little Ice Age （LIA） to the 20th century reached 1.1_＋1.2~C/100 a, which was the greatest in the past 500 years and probably the past 2000 years. At the 30-year scale, warming in the 20th century was quite notable, but the peak rate was still less than rates for previous periods, such as the rapid warming from the LIA to the 20th century and from the 270s-290s to 300s-320s. At the 10-year scale, the warming in the late 20th century was very evident, but it might not be unusual in the context of warming over the past 500 years. The exact timing, duration and magnitude of the warming peaks varied from region to region at all scales. The peak rates of the 100-year scale warming in the AD 180s-350s in northeastern China as well as those in the 260s-410s and 500s-660s in Tibet were all greater than those from the mid-19th to 20th century. Meanwhile, the rates of the most rapid cooling at scales of 30 to 100 years in the LIA were promi-nent, but they were also not unprecedented in the last 2000 years. At the 10-year scale, for the whole of China, the most rapid decadal cooling in the 20th century was from the 1940s to 1950s with a rate of -0.3±0.6℃/10 a, which was similar to rates for periods before the 20th century. For all regions, the rates of most rapid cooling in the 20th century were all less than those for previous periods.

关键词： China past 2000 years rates of temperature change

Unprecedented Warming Revealed from Multi-proxy Reconstruction of Temperature in Southern China for the Past 160 Years

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Advances in Atmospheric Sciences 2017年第8期34卷 977-982页

作者： Yang LIU Jingyun ZHENG Zhixin HAO xuezhen zhang Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

Using the southern limit of snowfall recorded in Chinese documents, chronologies of tree-ring width, and tree-ring stable oxygen isotope（δ^（18）O）, the annual temperature anomaly in southern China during 1850–2009 is reconstructed using the method of signal decomposition and synthesis. The results show that the linear trend was 0.47℃（100 yr）^（-1）over 1871–2009,and the two most rapid warming intervals occurred in 1877–1938 and 1968–2007, at rates of 0.125℃（10 yr）^（-1）and 0.258℃（10 yr）^（-1）, respectively. The decadal variation shows that the temperature in the moderate warm interval of the 1910s–1930s was notably lower than that of the 1980s–2000s, which suggests that the warming since the 1980s was unprecedented for the past 160 years, though a warming hiatus existed in the 2000s. Additionally, there was a rapid cooling starting from the 1860s,followed by a cold interval until the early 1890s, with the coldest years in 1892 and 1893. A slight temperature decline was also found from the 1940s to the late 1960s. This study provides an independent case to validate the global warming for the past 160 years and its hiatus recently, because the proxy data are not affected by urbanization.

关键词： centennial warming temperature reconstruction multi-proxy southern China

Assessing the effects of model parameter assumptions on surface-wave inversion results

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Earthquake Science 2024年第6期37卷 529-545页

作者： xuezhen zhang Xiaodong Song SinoProbe Laboratory School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards Beijing 100871China

Surface-wave inversion is a powerful tool for revealing the Earth's internal ***,aside from shear-wave velocity(v_(S)),other parameters can influence the inversion outcomes,yet these have not been systematically *** study investigates the influence of various parameter assumptions on the results of surface-wave inversion,including the compressional and shear velocity ratio(v_(P)/v_(S)),shear-wave attenuation(Q_(S)),density(ρ),Moho interface,and sedimentary *** constructed synthetic models to generate dispersion data and compared the obtained results with different parameter assumptions with those of the true *** results indicate that the v_(P)/v_(S) ratio,Q_(S),and density(ρ) have minimal effects on absolute velocity values and perturbation patterns in the ***,assumptions about the Moho interface and sedimentary layer significantly influenced absolute velocity values and perturbation *** an erroneous Mohointerface depth in the initial model of the inversion significantly affected the v_(S) model near that depth,while using a smooth initial model results in relatively minor *** assumption on the sedimentary layer not only affects shallow structure results but also impacts the result at greater ***-linear inversion methods outperform linear inversion methods,particularly for the assumptions of the Moho interface and sedimentary *** inversion with other data types,such as receiver functions or Rayleigh wave ellipticity,and using data from a broader period range or higher-mode surface waves,can mitigate these ***,incorporating more accurate prior information can improve inversion results.

关键词： shear-wave velocity model surface-wave inversion Moho interface sedimentary layer non-linear inversion

Accuracy assessment of global historical cropland datasets based on regional reconstructed historical data——A case study in Northeast China

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Science China Earth Sciences 2010年第11期53卷 1689-1699页

作者： Li BeiBei Fang XiuQi Ye Yu zhang xuezhen Beijing Normal Univ Sch Geog Beijing 100875 Peoples R China Chinese Acad Sci Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China

Historical cropland datasets are fundamental for quantifying the effects of human land use activities on climatic change and the carbon cycle. Two representative global land-use datasets, the Global Land Use Database (termed SAGE dataset) and the Historical Database of the Global Environment (termed HYDE dataset) have been established and used widely. Despite improvement of data quality and methodologies for extracting historical land use information, certain dataset limitations exist that need to be quantified and communicated to users so that they can make informed decisions on whether and how these land-use products should be used. The Cropland data of Northeast China (CNEC) is based on calibrated historical data and a multi-sourced data conversion model, and reconstructs cropland cover change in Northeast China over the last 300 years. Us- ing the CNEC as a reference, we evaluated the accuracy of cropland cover for SAGE and HYDE in Northeast China at spatial scales ranging from the entire Northeast China to provinces and even individual raster grid cells. Neither SAGE nor HYDE reflects real historical land reclamation. Cropland areas in SAGE are overestimated by 20.98 times in 1700 to 1.6 times in 1990. Although HYDE is better, there are significant disagreements in cropland area and distribution between HYDE and CNEC, especially in the 18th and 19th centuries. The proportion of total grid cells whose relative error was greater than 100% was 63.55% in 1700 and 53.27% in 1780. Global cropland dataset errors over Northeast China originate mainly from both the reverse calculation method for historical cropland data based on modern spatial patterns, and modern land-use outputs from satellite data.

关键词： LUCC dataset accuracy assessment Northeast China

Reconstructing temperature change in Central East China during 601-920 AD

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Chinese Science Bulletin 2010年第34期55卷 3944-3949页

作者： GE QuanSheng LIU HaoLong ZHENG JingYun zhang xuezhen Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Using historical records on first and last frost and snow,spring cultivation,David peach blossom,autumn crop harvest,grade of sea freeze and change in northern citrus boundary,we reconstructed temperature change during 601-920 *** mean temperature of the winter half-year(October to April)over Central East China during this period was about-0.22°C higher than that of the present(1961-2000 AD mean).During 601-820 AD,mean temperature was about-0.52°C higher than the *** 821-920 AD,the mean temperature was 0.42°C lower than the *** temperature fluctuations were characterized by a maximum amplitude of 1.05°C at the centennial scale,1.38°C at the 50-year scale,2.02°C at the 30-year scale,and 2.3°C at the 20-year *** were four peaks warmer than today(601-620 AD,mean of 1°C higher temperature;641-660 AD,1.44°C;701-720 AD,0.88°C;781-800 AD,0.65°C).Three cold periods were in 741-760,821-840,and 881-900 AD,the mean temperature of which was 0.37-0.87°C lower than the present.

关键词：温度变化中国平均温度广告春季栽培作物收获历史记录海域界线

Cropland cover change in Northeast China during the past 300 years

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Science China Earth Sciences 2009年第8期52卷 1172-1182页

作者： YE Yu FANG XiuQi REN YuYu zhang xuezhen CHEN Li School of Geography Beijing Normal UniversityBeijing 100875China Institute of Geographical Science and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Harbin Meteorological Bureau Harbin 150080China

Land use/cover change induced by human activities has emerged as a "global" phenomenon with Earth system consequences. Northeast China is an area where the largest land cultivation activities by migrants have happened in China during the past 300 years. In this paper, methods including documentary data calibration and multi-sourced data conversion model are used to reconstruct historical cropland cover change in Northeast China during the past 300 years. It is concluded that human beings have remarkably changed the natural landscape of the region by land cultivation in the past 300 years. Cropland area has increased almost exponentially during the past 300 years, especially during the past 100 years when the ratio of cropland cover changed from 10% to 20%. Until the middle of the 19th century, the agricultural area was still mainly restricted in Liaoning Province. From the late 19th century to the early 20th century, dramatic changes took place when the northern boundary of cultivation had extended to the middle of Heilongjiang Province. During the 20th century, three agricultural regions with high ratio of cropland cover were formed after the two phases of spatial expansion of cropland area in 1900s—1930s and 1950s—1980s. Since 1930s—1940s, the expansion of new cultivated area have invaded the forest lands especially in Jilin and Heilongjiang Provinces.

关键词： past 300 years Northeast China cropland land cover environmental change

A comparative study of seismic tomography models of the Chinese continental lithosphere

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Earthquake Science 2022年第3期35卷 161-185页

作者： xuezhen zhang Xiaodong Song Jiangtao Li Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards Beijing 100871China School of Earth and Space Sciences Peking UniversityBeijing 100871China School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China

The Chinese mainland is subject to complicated plate interactions that give rise to its complex structure and tectonics. While several seismic velocity models have been developed for the Chinese mainland, apparent discrepancies exist and, so far, little effort has been made to evaluate their reliability and consistency. Such evaluations are important not only for the application and interpretation of model results but also for future model improvement. To address this problem, here we compare five published shear-wave velocity models with a focus on model consistency. The five models were derived from different datasets and methods (i.e., body waves, surface waves from earthquakes, surface waves from noise interferometry, and full waves) and interpolated into uniform horizontal grids (0.5° × 0.5°) with vertical sampling points at 5 km, 10 km, and then 20 km intervals to a depth of 160 km below the surface, from which we constructed an averaged model (AM) as a common reference for comparative study. We compare both the absolute velocity values and perturbation patterns of these models. Our comparisons show that the models have large (> 4%) differences in absolute values, and these differences are independent of data coverage and model resolution. The perturbation patterns of the models also show large differences, although some of the models show a high degree of consistency within certain depth ranges. The observed inconsistencies may reflect limited model resolution but, more importantly, systematic differences in the datasets and methods employed. Thus, despite several seismic models being published for this region, there is significant room for improvement. In particular, the inconsistencies in both data and methodologies need to be resolved in future research. Finally, we constructed a merged model (ChinaM-S1.0) that incorporates the more robust features of the five published models. As the existing models are constrained by different datasets and methods, the m

关键词： Chinese mainland shear-wave velocity model model comparison continental lithosphere

A comparative study of seismic tomography models of Southwest China

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Earthquake Science 2023年第1期36卷 15-39页

作者： xuezhen zhang Xiaodong Song Feiyi Wang SinoProbe Laboratory School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards Beijing 100871China

The margin of the Tibetan Plateau of Southwest China is one of the most seismically active regions of China and is the location of the China Seismic Experimental Site(CSES).Many studies have developed seismic velocity models of Southwest China,but few have compared and evaluated these models which is important for further model ***,we compared six published seismic shear-wave velocity models of Southwest China on absolute velocity and velocity perturbation *** models are derived from different types of data(e.g.,surface waves from ambient noise and earthquakes,body-wave travel times,receiver functions) and inversion *** interpolated the models into a uniform horizontal grid(0.5° × 0.5°) and vertically sampled them at 5,10,20,30,40,and 60 km *** found significant differences between the six ***,we selected three of them that showed greater consistency for further *** further comparisons revealed systematic biases between models in absolute velocity that may be related to different data *** perturbation pattern of the model is especially divergent in the shallow part,but more consistent in the deep *** conducted synthetic and inversion tests to explore possible causes and our results imply that systematic differences between the data,differences in methods,and other factors may directly affect the ***,the Southwest China velocity model still has considerable room for improvement,and the impact of inconsistency between different data types on the model needs further ***,we proposed a new reference shear-wave velocity model of Southwest China(SwCM-S1.0) based on the three selected models with high *** believe that this model is a better representation of more robust features of the models that are based on different data sets.

关键词： model comparison shear-wave velocity model Southwest China