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Fluxes of CH4 and N_2O from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China

Journal of Environmental Sciences 2008年第2期20卷 207-215页

作者： YAN Yuping SHA Liqing CAO Min ZHENG Zheng TANG Jianwei WANG Yinghong ZHANG Yiping WANG Rui LIU Guangren WANG Yuesi SUN Yang Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Kunming 650223 China Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduated School of the Chinese Academy of Sciences Beijing 100049 China

CH4 and N2O fluxes from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China were measured for one year using closed static chamber technique and gas chromatography method. Three treatments were set in the studied field：（A） litter-free, （B） with litter, and （C） with litter and seedling. The results showed that the soil in our study was a sink of atmospheric CH4 and source of atmospheric N2O. The observed mean CH4 fluxes from treatments A, B, and C were -50.0 ± 4.0, -35.9 ± 2.8, -31.6 ± 2.8 μgC/（m^2·h）, respectively, and calculated annual fluxes in 2003 were -4.1, -3.1, and -2.9 kgC/hm^2, respectively. The observed mean N2O fluxes from treatments A, B, and C were 30.9 ± 3.1, 28.2 ± 3.5, 50.2±3.7 μgN/（m^2·h）, respectively, and calculated annual fluxes in 2003 were 2.8, 2.6, and 3.7 kgN/hm^2, respectively. seasonal variations in CH4 and N2O fluxes were significant among all the three treatments. The presence of litter decreased CH4 uptake during wet season （P 〈 0.05）, but not during dry season. There was a similar increase in seedlings-mediated N2O emissions during wet and dry seasons, indicating that seedlings increased N2O emission in both seasons. A strong positive relationship existed between CH4 fluxes and soil moisture for all the three treatments, and weak relationship between CH4 fluxes and soil temperature for treatment B and treatment C. The N2O fluxes correlated with soil temperature for all the three treatments.

关键词： global warming greenhouse gases rain forest seasonal variability soil moisture soil temperature

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An OGCM Simulation of seasonal and Interannual Variabilities in the Surface-Layer Pacific of the Equatorial Band

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Advances in Atmospheric Sciences 2002年第2期19卷 219-235页

作者： Boyin Huang and Zhengyu Liu Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison 1225 W. Dayton St., Madison, WI-53706, U.S.A. Department of Atmospheric and Oceanic Sciences University of Wisconsin-Madison Madison USA

The heat budget is analyzed in the surface-layer (0-50 m) Pacific of the equatorial band (10°S-10°N), using the simulation of an ocean general circulation model from 1945 to 1993. The analysis indicates that downward net surface heat flux from the atmosphere and ocean advective heat fluxes play distinct roles in seasonal and interannual variabilities of surface-layer ocean temperature. The surface heat flux dominantly determines the ocean temperature in the seasonal time-scale. But, it has a negative feedback to the ocean temperature in the interannual time-scale. The interannual variability of ocean temperature is largely associated with the cold advection from off-equatorial divergent flow in the central Pacific and from upwelling in the cold tongue. Both the surface heat flux and ocean advective heat fluxes are important to the ocean temperature during an El Nino event. The ocean. advective heat fluxes are further associated with local westward trade wind in the central Pacific. These results are largely consistent with some regional observational analyses.

关键词： seasonal variability Interannual variability Heat flux

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Annual Time-series Analyses of Total Gaseous Mercury Measurement and its Impact Factors on the Gongga Mountains in the Southeastern Fringe of the Qinghai-Tibetan Plateau

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Journal of Mountain Science 2008年第1期5卷 17-31页

作者： ZHU Wanze FU Xuewu FENG Xinbin Julia Y. Lu Institute of Mountain Hazard and Environment Chinese Academy of Sciences Chengdu 610041 China State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China Department of Chemistry and Biology Ryerson University Toronto Ontario M5B 2K3 Canada

Long-term monitoring programs for measurement of atmospheric mercury concentrations are presently recognized as powerful tools for local,regional and global studies of atmospheric long-range transport processes,and they could also provide valuable information about the impact of emission controls on the global budget of atmospheric mercury,their observance and an insight into the global mercury cycle. China is believed to be an increasing atmospheric mercury emission source. However,only a few measurements of mercury,to our knowledge,have been done in ambient air over China. The highly-time resolved atmospheric mercury concen-trations have been measured at Moxi Base Station (102°72′E 29°92′N,1640 m asl) of the Gongga Alpine Ecosystem Observation and Experiment Station of Chinese Academy of Sciences (CAS) from May 2005 to June 2006 by using a set of Automatic Atmospheric Mercury Speciation Analyzers (Tekran 2537A). Measurements were carried out with a time resolution of every 15 minutes. The overall average total gaseous mercury (TGM) covering the measurement periods was 4±1.38 ng·m-3 (N=57310),which is higher than the global background level of approximately 1.5～2.0 ng·m-3. The measurements in all seasons showed a similar diurnal change pattern with a high concentration during daytime relative to nighttime and maximum concentration near solar noon and minimum concentration immediately before sunrise. The presence of diurnal TGM peaks during spring and summer was found earlier than that during autumn and winter. When divided seasonally,it was found that the concentrations of TGM were highest in winter with 6.13 ± 1.78 ng·m-3 and lowest in summer with 3.17 ± 0.67 ng·m-3. There were no significant differences in TGM among wind sectors during each season. Whereas Hg generally exhibited significant correlations with the parameters,such as temperature,saturated vapor pressure,precipitation,ultraviolet radiation (UV) and atmospheric pressure at the whole measurement stage,

关键词： Total gaseous mercury (TGM) diurnal variability seasonal variability meteorological factor Gongga Mountains

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A shallow ice core from East Greenland showing a reduction in black carbon during 1990-2016

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Advances in Climate Change Research 2020年第4期11卷 360-369页

作者： DU Zhi-Heng XIAO Cun-De DOU Ting-Feng LI Chuan-Jin DING Ming-Hu Sangeeta SHARMA MA Xiang-Yu WANG Shi-Meng ZHANG Wang-Bing State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China Southern Marine Science and Engineering Guangdong Laboratory Guangzhou511458China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing100875China University of Chinese Academy of Science Beijing100049China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing100081China Climate Research Division Environment and Climate Change CanadaTorontoM3H 5T4Canada School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing210023China

This study reports on the measurements of ion and refractory black carbon(rBC)concentrations in a shallow(10.96 m)ice core sample which was drilled from the field site of the East Greenland Ice Core Project(EGRIP)in July,*** results provide a recent record of rBC deposition in the East Greenland ice sheet from 1990 to *** annual variability in oxygen(δ^(18)O)and hydrogen(δD)isotopic compositions indicated that notably warm events occurred since *** in rBC occurred during summer seasons,which may be attributed to the burning of biomass in boreal *** rBC record and analysis of historical air trajectories using the HYSPLIT model indicated that anthropogenic BC emissions from Russia,North America and Europe contributed to the majority of rBC deposition in the Greenland region,and a reduction in anthropogenic BC consumption in these areas played a dominant role in the decrease in BC concentrations since *** record also suggests that the emissions from the East Asian region(China)contributed very little to the recorded BC concentrations in East Greenland ice *** model results indicated that radiative forcing due to BC had decreased significantly since 1990,and had remained below 0.02W m^(-2) since 2000.

关键词： East Greenland Ice core Black carbon seasonal variability Potential emission sources

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Dynamic features of near-inertial oscillations in the Northwestern Pacific derived from mooring observations from^2015 to 2018

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Journal of Oceanology and Limnology 2020年第4期38卷 1092-1107页

作者： HU Shijian LIU Lingling GUAN Cong ZHANG Linlin WANG Jianing WANG Qingye MA Jie WANG Fujun JIA Fan FENG Junqiao LU Xi WANG Fan HU Dunxin CAS Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China College of Marine Science University of Chinese Academy of SciencesQingdao 266071China

Near-inertial oscillation is an important physical process transferring surface wind energy into deep *** investigated the near-inertial kinetic energy(NIKE)variability using acoustic Doppler current profiler measurements from a mooring array deployed in the tropical western Pacific Ocean along 130°E at 8.5°N,11°N,12.6°N,15°N,and 17.5°N from September 2015 to January *** features,decay timescales,and significant seasonal variability of the observed NIKE were *** the mooring sites of 17.5°N,15°N,and 12.6°N,the NIKE peaks occurred in boreal autumn and the NIKE troughs were observed in boreal *** contrast,the NIKE at 11°N and 8.5°N showed peaks in winter and troughs in *** cyclones and strong wind events played an important role in the emergence of high-NIKE events and explained the seasonality and latitudinal characteristics of the observed NIKE.

关键词： near-inertial kinetic energy western Pacific Ocean tropical cyclones mooring array seasonal variability

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A fresh look at the deepwater overflow in the Luzon Strait

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Acta Oceanologica Sinica 2017年第5期36卷 1-8页

作者： ZHU Yaohua SUN Junchuan WEI Zexun WANG Yonggang FANG Guohong QU Tangdong Key Laboratory of Marine Science and Numerical Modeling The First Institute of OceanographyState Oceanic Administration Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology Joint Institute for Regional Earth System Science and Engineering University of California

On the basis of the latest version of a U.S. Navy generalized digital environment model （GDEM-V3.0） and World Ocean Atlas （WOA13）, the hydraulic theory is revisited and applied to the Luzon Strait, providing a fresh look at the deepwater overflow there. The result reveals that：（1） the persistent density difference between two sides of the Luzon Strait sustains an all year round deepwater overflow from the western Pacific to the South China Sea （SCS）; （2） the seasonal variability of the deepwater overflow is influenced not only by changes in the density difference between two sides of the Luzon Strait, but also by changes in its upstream layer thickness; （3） the deepwater overflow in the Luzon Strait shows a weak semiannual variability; （4） the seasonal mean circulation pattern in the SCS deep basin does not synchronously respond to the seasonality of the deepwater overflow in the Luzon Strait. Moreover, the deepwater overflow reaches its seasonal maximum in December （based on GDEM-V3.0） or in fall （October-December, based on the WOA13）, accompanied by the lowest temperature of the year on the Pacific side of the Luzon Strait. The seasonal variability of the deepwater overflow is consistent with the existing longest （3.5 a） continuous observation along the major deepwater passage of the Luzon Strait.

关键词： Luzon Strait deepwater overflow seasonal variability South China Sea

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seasonal Characteristics of Precipitation in 1998 over East Asia as Derived from TRMM PR

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Advances in Atmospheric Sciences 2003年第4期20卷 511-529页

作者：傅云飞林一骅刘国胜王强 Department of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026 LASGInstitute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Department of Meteorology Florida State UniversityUSA School for Continuing Education University of Science and Technology of ChinaHefei 230026

Precipitation radar data derived from the Tropical Rainfall Measuring Mission (TRMM) satellite are used to study precipitation characteristics in 1998 over East Asia (10?38癗, 100C-145癊), especially over mid-latitude land (continental land) and ocean (East China Sea and South China Sea). Results are compared with precipitations in the tropics. Yearly statistics show dominant stratiform rain events over East Asia (about 83.7% by area fraction) contributing to 50% of the total precipitation. Deep convective rains contribute 48% to the total precipitation with a 13.7% area fraction. The statistics also show the unimportance of warm convective rain in East Asia, contributing 1.5% to the total precipitation with a 2.7% area fraction. On a seasonal scale, the results indicate that the rainfall ratio of stratiform rain to deep convective rain is proportional to their rainfall pixel ratio. seasonal precipitation patterns compare well between Global Precipitation Climatology Project rainfall and TRMM PR measurements except in summer. Studies indicate a clear opposite shift of rainfall amount and events between deep convective and stratiform rains in the meridional in East Asia, which corresponds to the alternative activities of summer monsoon and winter monsoon in the region. The vertical structures of precipitation also exhibit strong seasonal variability in precipitation Contoured Rainrate by Altitude Diagrams (CRADs) and mean profiles in the mid-latitudes of East Asia. However, these structures in the South China Sea are of a tropical type except in winter. The analysis of CRADs reveals a wide range of surface rainfall rates for most deep convective rains, especially in the continental land, and light rain rate for most stratiform rains in East Asia, regardless of over land or ocean.

关键词： TRMM PR seasonal variability precipitation structure

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Comparative simulation study of effects of eddy-topography interaction in the East/Japan Sea deep circulation

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Acta Oceanologica Sinica 2015年第7期34卷 1-18页

作者： CHOI Youngjin Center for Earth Information Science and Technology Japan Agency for Marine-Earth Science and Technology Geo System Research Corporation

In this study the structure and seasonal variations of deep mean circulation in the East/lapan Sea （E/S） were numerically simulated using a mid-resolution ocean general circulation model with two different parameterizations for the eddy-topography interaction （ETI）. The strong deep mean circulations observed in the EIS are well reproduced when using the ETI parameterizations. The seasonal variability in the EIS deep layer is shown by using ETI parameterization based on the potential vorticity approach, while it is not shown in the statistical dynamical parameterization. The driving mechanism of the strong deep mean currents in the E/S are discussed by investigating the effects of model grids and parameterizations. The deep mean circulation is more closely related to the baroclinic process and potential vorticity than it is to the wind driven circulation.

关键词： East/Iapan Sea deep mean current seasonal variability ocean general circulation model eddy- topography interaction

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Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small drinking water systems

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Frontiers of Environmental Science & Engineering 2015年第1期9卷 171-179页

作者： Roberta DYCK Genevieve COOL Manuel RODRIGUEZ Rehan SADIQ School of Engineering University of British Columbia Okanagan Kelowna V1V 1V7 Canada Ecole superieure d'amenagement du territoire Universite Laval Quebec G1V 0A6 Canada

seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems （〈 3000 residents） supplied by surface waters. Residual chlorine and trihalomethanes （THM） were measured over seven years （2003-2009）. Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM （TTHM） and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

关键词： drinking water residual chlorine seasonal variability small municipal systems treatment technologies trihalomethanes

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Evaluation of Precipitation in Multi-Generation Reanalyses with Land Observations over Zhejiang Province

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Journal of Tropical Meteorology 2021年第2期27卷 148-160页

作者： MA Hao YIN Yue XIAO Jing-jing XU Zhe-yong YANG Ming GAO Da-wei GE Jing-wen Zhejiang Climate Center Hangzhou 310017 China Zhoushan Meteorological Bureau Zhoushan 316021 China Zhejiang Meteorological Information and Network Center Hangzhou 310017 China

Based on various statistical indices,the abilities of multi-generation reanalyses,namely the NCEP/NCAR Reanalysis 1(R1),the NCEP-DOE Reanalysis 2(R2)and the NCEP Climate Forecast System Reanalysis(CFSR),to reproduce the spatiotemporal characteristics of precipitation over Zhejiang Province are comprehensively *** mean absolute bias percentages for three reanalyses are 20%(R1),10%(R2)and 37%(CFSR).R2(R1)gives the best(worst)general depiction of the spatial characteristics of the observed precipitation climatology,whereas a significant wet bias is noticed in the *** reanalyses reasonably reproduce the interannual variability with the correlation coefficients of 0.72(R1),0.72(R2)and 0.84(CFSR).All reanalyses well represent the first two modes of the observed precipitation through Empirical Orthogonal Function analysis,with CFSR giving the best capture of the principal *** root-mean-square error(RMSE)is the largest(smallest)in the CFSR(R2).The large RMSE of CFSR in summer(especially in June)contributes mostly to its systematic wet *** 2001,the wet bias of CFSR substantially weakens,probably attributed to increasing observations assimilated in the *** a monthly basis,the percentage of neutral bias cases are similar for all reanalyses,while the ratio of positive(negative)bias cases for CFSR is distinctly larger(smaller)than that of R1 and *** proportions of negative bias cases for R1 and R2 begin to increase after 2001 while keeping stable for *** a daily basis,all reanalyses give good performances of reproducing light rain;however,the reflection of moderate rain and heavier rain by the CFSR is better than R1 and ***,despite being a third-generation reanalysis product,the CRSR does not exhibit comprehensive superiorities over R1 and R2 in all aspects on a regional scale.

关键词： multi-generation reanalyses precipitation RMSE spatiotemporal modes seasonal variability bias level

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