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Variations in monsoon precipitation over southwest China during the last 1500 years and possible driving forces

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Science China Earth Sciences 2022年第5期65卷 949-965页

作者： Bin LIU Enguo SHENG Keke YU Kang’en ZHOU Jianghu LAN College of Resources and Environment Zunyi Normal UniversityZunyi 563006China State key laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China shaanxi key laboratory of disasters monitoring&mechanism simulation Baoji University of Arts and SciencesBaoji 721013China School of Earth System Science Institute of Surface-Earth System ScienceTianjin UniversityTianjin 300072China

Understanding hydroclimatic patterns and their possible driving mechanisms during distinct climate periods over the last 1500 years—such as the Medieval Warm Period(MWP),the Little Ice Age(LIA),and the Current Warm Period—is crucial for predicting future changes to monsoon precipitation in southwest China under global warming *** this study,based on ^(210)Pb and ^(137)Cs dating of surface sediments and AMS ^(14)C dating of terrestrial plant residues,we establish a robust age model that covers the last~1500 years(AD 439–2012)at Lake Yihai in southwest *** use analyses of multiple geochemical proxy indices,including loss on ignition at 550℃,total organic carbon,total nitrogen,C/N ratios,and stable carbon isotopes of organic matter to reconstruct changes in summer monsoon precipitation at Lake Yihai during the last~1500 *** results show that,over southwest China,warm and dry climate conditions prevailed during the MWP(AD 1000–1400)and the past 200 years,whereas conditions during the LIA(AD 1400–1800)were cold and *** is consistent with evidence from other geological records over southwest China,such as stalagmite and lake sediment *** hydroclimatic patterns have occurred over the last 1500 years in adjacent tropical/subtropical monsoon regions where the climate is similarly dominated by the Indian summer monsoon(e.g.,South China,the South China Sea,Southeast Asia,Northeast India).We suggest that the meridional migration of the mean position of the Inter-tropical Convergence Zone,and El Niño/Southern Oscillation conditions which are linked to tropical Pacific sea surface temperature,are responsible for centennial-scale hydroclimatic patterns over southwest China and adjacent areas during the last 1500 years.

关键词： Lake sediments Southwest China Monsoon precipitation Distinct climate periods Inter-tropical Convergence Zone

Changing Trend and Mutation Analysis of Number of Fog and Haze Days in Baoji City during 1981-2013

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Meteorological and Environmental Research 2016年第4期7卷 5-9页

作者： Li Gaiping Zhou Qi Zhai Yaqian key laboratory of Disaster monitoring and mechanism simulation of shaanxi Province Baoji University of Arts and Sciences

Based on data of number of fog and haze days in Baoji City from 1981 to 2013,the changing trends and mutation of number of fog and haze days in Baoji over the past 33 years were analyzed by using trend coefficient,tendency rate,linear regression analysis,anomaly percentage,Mann-Kendall mutation test and sliding t *** results showed that during the 33 years,the number of fog and haze days in Baoji declined by 16.253d/10 a,and there was a cyclical turbulence every 6,15 or *** frequency of fog and haze weather was the highest in winter,followed by spring and autumn,while it was the lowest in *** to the anomaly percentage of the number of fog and haze days in 12 months during 1981-2013,the anomaly percentage changed most greatly in July,followed by September,October,April,May,June,August,February and March,but it fluctuated less greatly in *** number of fog and haze days from 1981 to 2013had obvious mutation trends in a single year and a single season,and mutation types are different.

关键词： Number of fog and haze days Changing features Mann-Kendall method Sliding t test method Baoji China

Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911

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Journal of Geographical Sciences 2018年第3期28卷 337-350页

作者：万红莲宋海龙朱婵婵张蓓蓓张咪 College of Geography and Environment Baoji University of Arts and Sciences key laboratory of Disaster monitoring and mechanism simulation of shaanxi Province Baoji University of Arts and Sciences Suide Middle School

Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average, cumulative anomaly and wavelet analysis. The results are as follows:(1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji. Among these events, droughts and floods occurred separately 191 and 106 times, which accounted for 64.31% and 35.69% of the total events, respectively.(2) We observed distinct characteristics of flood and drought events in Baoji in different phases. The climate was relatively dry from 1368 to 1644. A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804. The climate was relatively wet from 1805 to 1911. Moreover, we observed a pattern of alternating dry and wet periods from 1368 to 1911. In addition, 3 oscillation periods of drought and flood events occurred around 70 a, 110 a and 170 a, which corresponded to sunspot cycles.(3) We also observed an obvious spatial difference in drought and flood events in Baoji. The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods.(4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change. Since the 1760s, global climatic deterioration has frequently led to extreme drought and flood events.

关键词： Baoji area drought and flood disaster chain climate change spatio-temporal distribution waveletanalysis

Composition and size distribution of wintertime inorganic aerosols at ground and alpine regions of northwest China

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Chinese Chemical Letters 2024年第11期35卷 238-242页

作者： Haijiao Liu Qiao Feng Yu Huang Feng Wu Yali Liu Minxia Shen Xiao Guo Wenting Dai Weining Qi Yifan Zhang Lu Li Qiyuan Wang Bianhong Zhou Jianjun Li State key laboratory of Loess and Quaternary Geology Key Lab of Aerosol Chemistry and PhysicsInstitute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China Xi'an Institute for Innovative Earth Environment Research Xi'an 710061China College of Geography and Environment Baoji University of Arts and SciencesShaanxi Key Laboratory of Disaster Monitoring and Mechanism SimulationBaoji 721013China National Observation and Research Station of Regional Ecological Environment Change and Comprehensive Management in the Guanzhong Plain ShaanxiXi'an 710061China

Water-soluble inorganic ions(WSIIs)play a pivotal role in atmospheric chemical reactions,particularly influencing the formation of secondary particulate matter.A comprehensive grasp of the vertical distribution of atmospheric pollutants holds immense significance in understanding the diffusion and transportation of these *** study investigates the WSIIs of PM_(2.5)and size-segregated particles at the top(~2060 m a.s.l.)and foot of *** during the winter of *** the measured ions present significant higher concentrations(1.9~6.9 times)at the foot than the ***^(-)and K^(+)at the foot are more than 4 times of those at the top,whereas Ca^(2+)and Mg^(2+)are only 1.3-1.9 times *** particle size distribution of NO_(3)^(-),SO_(4)^(2-),K^(+)and Cl^(-)demonstrate a single peak distribution(0.7-1.1μm)at the foot,but with a bimodal distribution(0.7-1.1μm and 4.7-5.8μm)at the *** differences suggest that the aerosol at the alpine region is mainly transported via long-distance from Northwest/North China,but limited influenced by vertical transport through valley *** changes of concentration and size distribution of WSIIs in dust event and non-dust period indicate that the effects of dust event on aerosols at ground surface were weaker than that of the free troposphere of Guanzhong ***,our study underscores the dominant influence of NO_(3)^(-)in shaping the gas-particle distribution of ammonia within the winter free *** results highlight the significant role of long-range transport on aerosols in the free troposphere in Guanzhong Plain,Northwest China.

关键词： Water-soluble inorganic ions Size distribution Aerosol acidity Ammonia Free troposphere

Mixing state of individual carbonaceous particles during a severe haze episode in January 2013,Nanjing,China

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Particuology 2015年第3期13卷 16-23页

作者： Honglei Wang Bin Zhu Zefeng Zhang Junlin An Lijuan Shen Collaborative Innovation Center on Forecast and Evaluation of Meteorological disasters Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological AdministrationNanjing University of Information Science and Technology Jiaxing Environmental monitoring Station

Chemical composition, hourly counts, and sizes of atmospheric carbonaceous particles were measured to investigate their mixing state on clear and hazy days. 823,122 carbonaceous particles with sizes 0.2-2.0μm was analyzed using a single-particle aerosol mass spectrometer from 1st to 17th January 2013. Particle types included biomass/biofuel burning particles （biomass）, element carbon （EC-dominant） particles that were also mixed with biomass/biofuel burning species （EC-biomass） or secondary species （EC-secondary）, organic carbon （OC）, internally mixed OC and EC （OCEC）, ammonium-containing （ammo- nium） and sodium-containing （sodium） particles. On clear days the top ranked carbonaceous particle types were biomass （48.2%）, EC-biomass （15.7%）, OCEC （11.1%）, and sodium （9.6%）, while on hazy days they were biomass （37.3%）, EC-biomass （17,6%）, EC-secondary （16.6%）, and sodium （12.7%）. The fractions of EC-secondary, ammonium （10%）, and sodium particle types were elevated on hazy days. Numbers of EC-secondary particles were more than four times those on clear days （4.1%）. Thus, carbonaceous particles mixed with ammonium, nitrate and sulfate during aging and transport, enhancing their light extinction effects and hygroscopic growth under high relative humidity on hazy days, further reducing visibility. Our real-time single-particle data showed that changes to mixing state had a significant impact on light extinction during haze events in Nanjing.

关键词： HazeSingle particleMixing stateSPAMSCarbonaceous particleSecondary aerosols

Coexistence Analysis between 5G System and Fixed- Satellite Service in 3400-3600 MHz

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China Communications 2018年第11期15卷 25-32页

作者： Haifeng Tan Yanjie Liu Zhiyong Feng Qixun Zhang key laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China The State Radio monitoring Center Shaanxi Monitoring Station Xi'an 710200 China

The 3400-3600 MHz band is one of the most important candidate frequency bands for the rollout of 5 G system. However, the coexistence between 5 G system and fixed-satellite service(FSS) in this frequency band is one of the most challenging problems for both academic researchers and industry engineers. In this paper, the saturation interference from 5 G base stations to the existing FSS above 3600 MHz is analyzed and the coexistence solution is achieved, which can reduce the interference and guarantee the coexistence between 5 G system and FSS. Furthermore, the Monte Carlo simulation, laboratory test and field test are carried out to verify the coexistence *** show that an isolation distance of 1-2 km is required to avoid the saturation interference in terms of the adjacent bands *** further reduce the isolation distance to 50 m, additional isolation of 35 dB will be necessary, which can be fulfilled by installing a filter at the input port of LNB from a real implementation perspective.

关键词： 5G system fixed-satellite service coexistence analysis

Study on Changes of Industrial Structure and Its Ecological Environment Benefit in shaanxi Province

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Meteorological and Environmental Research 2016年第5期7卷 36-39页

作者： Wen Yanjun Liu Xi Zhai Yaqian shaanxi key laboratory of Disaster monitoring and mechanism simulation Baoji University of Arts and Science College of Geography and Environment Baoji University of Arts and Sciences

[Objective] To reduce influences of adjustment of regional industrial structure on ecological environment,promote coordinated development of regional economy and ecological environment,and improve the relationship between human beings and natural environment. [Method]Based on the statistical data of shaanxi Province during 1978- 2013,the ecological environmental impact index and effect index of industrial structure in shaanxi Province were calculated,and then the ecological environment benefit of changes in industrial structure in shaanxi Province from1978 to 2013 was assessed quantitatively. [Result]The impact of changes in industrial structure on ecological environment in shaanxi Province was moderate,but later changes in industrial structure had greater influences on ecological environment than before. [Conclusion]Industrial structure in shaanxi Province should be optimized further to ensure the healthy development of ecological environment.

关键词： shaanxi Province Changes in industrial structure Ecological environment benefit China

Exploration of the formation mechanism and source attribution of ambient ozone in Chongqing with an observation-based model

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Science China Earth Sciences 2018年第1期61卷 23-32页

作者： SU Rong LU KeDing YU JiaYan TAN ZhaoFeng JIANG MeiQing LI Jing XIE ShaoDong WU YuSheng ZENG LiMin ZHAI ChongZhi ZHANG YuanHang State key Joint laboratory of Environmental simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing 100871 China Ecological and Environmental monitoring Center ofChongqing Chongqing 401147 China

An intensive field campaign was conducted in Chongqing during the summer of 2015 to explore the formation mechanisms of ozone pollution. The sources of ozone, the local production rates, and the controlling factors, as well as key species of volatile organic compounds(VOCs), were quantified by integrating a local ozone budget analysis, calculations of the relative incremental reactivity, and an empirical kinetic model approach. It was found that the potential for rapid local ozone formation exists in Chongqing. During ozone pollution episodes, the ozone production rates were found to be high at the upwind station Nan Quan, the urban station Chao Zhan, and the downwind station Jin-Yun Shan. The average local ozone production rate was 30×10^(-9) V/V h^(-1) and the daily integration of the produced ozone was greater than 180×10^(-9) V/V. High ozone concentrations were associated with urban and downwind air masses. At most sites, the local ozone production was VOC-limited and the key species were aromatics and alkene, which originated mainly from vehicles and solvent usage. In addition, the air masses at the northwestern rural sites were NO_x-limited and the local ozone production rates were significantly higher during the pollution episodes due to the increased NOx concentrations. In summary, the ozone abatement strategies of Chongqing should be focused on the mitigation of VOCs. Nevertheless, a reduction in NO_x is also beneficial for reducing the regional ozone peak values in Chongqing and the surrounding areas.

关键词： Ozone Chongqing Photochemistry NO_x VOCs Sensitivity analysis Relative incremental reactivity EKMA

Rock-magnetic characteristics and mechanisms of the Titel loess-paleosol sequence in northern Serbia since late Middle Pleistocene

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Science China Earth Sciences 2022年第3期65卷 503-517页

作者： Zhi LIU Xiuming LIU Slobodan B.MARKOVIC Bin LU Ruina HE College of Geography and Environment Baoji University of Arts and SciencesBaoji 721013China key laboratory of Disaster monitoring and mechanism simulation of shaanxi Province Baoji 721013China School of Geographical Sciences Fujian Normal UniversityFuzhou 350007China Department of Earth and Environmental Sciences Macquarie UniversitySydneyNSW 2109Australia Chair of Physical Geography Faculty of SciencesUniversity of Novi SadTrg Dositeja Obradovica 321000 Novi SadSerbia

The changing pattern of magnetic characteristics in eastern European loess deposits is the most similar across the world to that of the Chinese Loess Plateau,both of which are dominated by the strength of *** a systematical study to the rock magnetism of eastern European loess is not only helpful for understanding the paleoclimatic information preserved by themselves,but also beneficial for promoting the cognition of the pedogenic mechanism in loess *** this study,a detailed rock-magnetic analysis of seventy loess/paleosol samples,taken from the Titel Loess Plateau in northern Serbia,is carried out for a better understanding of the magnetic records since late Middle *** results provide us some ***,the magnetic susceptibility values of the paleosols in the Titel loess-paleosol sequence are generally less than 100×10^(-8)m^(3)kg^(-1),significantly lower than those of the loess sections in the Chinese Loess Plateau,even though they are under similar climatic ***,the behaviors of the parameters related to the distributions of magnetic particles in these two regions are *** difference in the contents of ferrimagnetic minerals is the leading reason that caused the difference in their magnetic characteristics,but the mechanism is still open to ***,based on the analysis of thermomagnetic curves,a gradually increasing trend of the relative contents of maghemite over the last four glacial-interglacial cycles is *** realization of thermally unstable maghemite from Chinese loess leads us to speculate that the long-term increasing trend of the relative contents of maghemite in Titel loess-paleosol sequence likely is a mineralogical response to the progressive enhancement of continental climate in the Pannonian Basin since the Middle Pleistocene.

关键词： Eastern European loess Magnetic susceptibility Pedogenesis Environmental magnetism Paleoclimate

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