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Contribution of high-latitude permafrost regions in the Northern Hemisphere to global wildfire carbon emissions

Science China Earth Sciences 2024年第10期67卷 3239-3251页

作者： Xingru ZHU Xiyan XU gensuo jia Key Laboratory of Regional Climate-Environment for East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Wildfires are major disturbances in permafrost ecosystems, with increasing frequency and intensity in recent years. In permafrost regions, wildfires not only burn surface and subsurface organic matter but also accelerate permafrost thawing,releasing significant amounts of greenhouse gases such as carbon dioxide and methane into the atmosphere. However, the contribution of high-latitude permafrost regions in the Northern Hemisphere to global wildfire carbon emissions remains poorly understood. This study integrates remote sensing data and ground observations to analyze the contributions of aboveground and belowground fuel combustion in high-latitude permafrost regions to global wildfire carbon emissions from 2002 to 2020, as well as the spatiotemporal variations in these contributions. Our findings indicate that permafrost regions contribute approximately11.96% of global wildfire carbon emissions, with aboveground emissions accounting for approximately 3.94% of global aboveground emissions and belowground emissions contributing approximately 63.57% of global belowground emissions. The contribution of high-latitude permafrost regions to global emissions peaked in July and August, whereas the continuous permafrost zones(areas with more than 90% permafrost coverage) showed the most significant increase in June and July. The contributions of both aboveground and belowground emissions from high-latitude permafrost regions to global wildfire emissions have been increasing, primarily due to the reduction in global wildfire emissions, in contrast with the rising emissions from wildfires in high-latitude permafrost regions. This study highlights the significant role of wildfires, particularly the combustion of belowground biomass in high-latitude permafrost regions, in global carbon emissions. The decomposition and combustion of organic carbon in permafrost regions due to wildfires release more greenhouse gases into the atmosphere, potentially amplifying the positive feedback

关键词： Wildfire Permafrost Carbon emissions Climate change Belowground fuel consumption

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Accelerated rise in wildfire carbon emissions from Arctic continuous permafrost

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Science Bulletin 2024年第15期69卷 2430-2438页

作者： Xingru Zhu gensuo jia Xiyan Xu Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Wildfires over permafrost put perennially frozen carbon at ***,wildfire emissions from biomass burning over the diverse range of permafrost regions and their share in global wildfire emissions have not been *** results showed a dramatic increase in wildfire carbon emissions from permafrost regions over the period 1997–*** share of permafrost in global wildfire CO_(2) emissions increased from 2.42%in 1997 to 20.86%in *** wildfire emissions from continuous permafrost region is the single largest contributor to increased emissions in northern permafrost ***-induced emissions from 2019 to 2021 alone accounted for approximately 40%of the 25-year total CO_(2) emissions from continuous permafrost *** rise in wildfire emissions from continuous permafrost regions is explained by desiccation within a 5–10 cm soil depth,where wildfires combust belowground *** findings highlight the acceleration of fire-induced carbon emissions from continuous permafrost regions,which disturb the organic carbon stock and accelerate the positive feedback between permafrost degradation and climate warming,thus stimulating permafrost towards a climatic tipping point.

关键词： Wildfire Permafrost Carbon Fuel moisture CO_(2) Continuous permafrost

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The role of big Earth data in understanding climate change

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Big Earth Data 2020年第2期4卷 91-93页

作者： gensuo jia CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina

Climate-related changes have already been observed at various spatial and temporal scales,along with frequent extreme climate events and emerging issues in great ***,the impacts of climate change are expected to become increasingly more severe for more people and places as the amount of warming ***,great challenges and uncertainties exist in understanding climate change and its complex impacts,largely due to the limited availability and compatibility of large-scale data.

关键词： climate Earth warming

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Identifying and Quantifying Pixel-Level Uncertainty among Major Satellite Derived Global Land Cover Products

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Journal of Meteorological Research 2020年第4期34卷 806-821页

作者： Hao GAO gensuo jia Yu FU National Satellite Meteorological Center China Meteorological AdministrationBeijing 100081 Key Laboratory of Regional Climate–Environment for Temperate East Asia(RCE-TEA) Chinese Academy of SciencesBeijing 100029 Climate Change Research Center Chinese Academy of SciencesBeijing 100029

Accurate global land cover(GLC), as a key input for scientific communities, is important for a wide variety of applications. In order to understand the current suitability and limitation of GLC products, the discrepancy and pixellevel uncertainty in major GLC products in three epochs are assessed in this study by using an integrated uncertainty index(IUI) that combines the thematic uncertainty and local classification accuracy uncertainty. The results show that the overall spatial agreements(Ao values) between GLC products are lower than 58%, and the total areas of forests are very consistent in major GLC products, but significant differences are found in different forest *** misclassification among different forest classes and mosaic types can account for about 20% of the total disagreements. The mean IUI almost reaches 0.5, and high uncertainty mostly occurs in transition zones and heterogeneous areas across the world. Further efforts are needed to make in the land cover classifications in areas with high uncertainty. Designing a classification scheme for climate models, with explicit definitions of land cover classes in the threshold of common attributes, is urgently needed. Information of the pixel-level uncertainty in major GLC products not only give important implications for the specific application, but also provide a quite important basis for land cover fusion.

关键词： global land cover(GLC) discrepancies thematic similarity local accuracy pixel-level uncertainty

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Heterogeneous Trends of Precipitation Extremes in Recent Two Decades over East Africa

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Journal of Meteorological Research 2021年第6期35卷 1057-1073页

作者： Zacharia Florence MTEWELE Xiyan XU gensuo jia Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Physics Department University of Dares SalaamDares Salaam P.O.Box 35063Tanzania

East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged ***,systematic regional assessment of precipitation extremes across seasons has received little attention,and most previous studies of precipitation extremes have employed many indices and sparse gauge observations giving marginalized *** this study,we use three precipitation extreme indices to examine the intensity of the highest single-day rainfall record(rx1day),prevalence of very heavy rainfalls(r30mm),and persistence of successive wet days(cwd)at both annual and seasonal scales over recent two decades(1998-2018)based on the Tropical Rainfall Measuring Mission(TRMM)Multisatellite Precipitation Analysis *** results show that the most intensive and frequent precipitation extremes are noticeable from January to May across the areas extending from Madagascar to the Tanzanian coastal *** areas also exhibit patches of significant increasing trends in frequency,duration,and intensity of precipitation extremes annually and ***,significant declines in frequency and intensity of precipitation extremes are observed from western Ethiopia to Congo-Uganda,especially in *** October-December season witnesses higher interannual variability amounting to overall weak and less significant *** subregional assessment shows overall declining intensity and frequency of precipitation extremes in northern part of the study *** wetness duration increased,with persistence of moderate wet days and slight reduction of severe *** study unveils higher susceptibility of the East African region to the widely observed hotspots of precipitation extremes posing threats to food security,water resource,and human *** region should consider upscaling irrigation schemes in addition to planning resilient and supportive infrastructures to withstand the upsurging precipitation extremes,especially al

关键词： precipitation extremes East Africa extreme indices Tropical Rainfall Measuring Mission(TRMM) climate extremes

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Simulating Net Carbon Budget of Forest Ecosystems and Its Response to Climate Change in Northeastern China Using Improved FORCCHN

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Chinese Geographical Science 2012年第1期22卷 29-41页

作者： ZHAO Junfang YAN Xiaodong jia gensuo Chinese Academy of Meteorological Sciences Beijing 100081 China Beijing Normal University Beijing 100875 China Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

As dominant biomes,forests play an important and indispensable role in adjusting the global carbon balance under climate ***,there are scientific and political implications in investigating the carbon budget of forest ecosystems and its response to climate *** we synthesized the most recent research progresses on the carbon cycle in terrestrial ecosystems,and applied an individual-based forest ecosystem carbon budget model for China(FORCCHN) to simulate the dynamics of the carbon fluxes of forest ecosystems in the northeastern *** FORCCHN model was further improved and applied through adding variables and modules of precipitation(rainfall and snowfall) interception by tree crown,understory plants and *** results showed that the optimized FORCCHN model had a good performance in simulating the carbon budget of forest ecosystems in the northeastern *** 1981 to 2002,the forests played a positive role in absorbing carbon ***,the capability of forest carbon sequestration had been gradually declining during the the same *** for the average spatial distri-bution of net carbon budget,a majority of the regions were carbon *** scattered areas in the Heilongjiang Province and the Liaoning Province were identified as carbon *** net carbon budget was apparently more sensitive to an increase of air temperature than change of precipitation.

关键词： net carbon budget climate change northeastern China improved FORCCHN

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Quantifying the response of surface urban heat island to urbanization using the annual temperature cycle model

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Geoscience Frontiers 2022年第1期13卷 478-487页

作者： Huidong Li Yuyu Zhou gensuo jia Kaiguang Zhao Jinwei Dong Department of Geological and Atmospheric Sciences Iowa State UniversityAmes 50011USA Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Ohio Agricultural Research and Development Center School of Environment and Natural ResourcesThe Ohio State UniversityWoosterOH 44691USA Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101

Urban heat island(UHI),driving by urbanization,plays an important role in urban sustainability under climate ***,the quantification of UHI’s response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification *** study proposed a framework to quantify the response of surface UHI(SUHI)to urban expansion using the annual temperate cycle *** built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from *** then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying ***,the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural ***,the increase in SUHI under urban expansion was more significant in daytime compare to *** found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban ***,urban greening led to the decrease in summer daytime SHUI in central urban *** findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion,providing a scientific basis for prediction and mitigation of UHI.

关键词： Urban heat island Urbanization Spatiotemporal dynamics Annual temperature cycle model Diurnal temperature range

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Satellite-Based Estimation of Daily Average Net Radiation under Clear-Sky Conditions

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Advances in Atmospheric Sciences 2014年第3期31卷 705-720页

作者： HOU jiangtao jia gensuo ZHAO Tianbao WANG Hesong TANG Bohui Key Laboratory of Regional Climate-Environment Research for East Asia Institute of Atmospheric Physics Chinese Academy of Sciences University of the Chinese Academy of Sciences State Key Laboratory of Resources and Environment Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

ABSTRACT Daily average net radiation （DANR） is an important variable for estimating evapotranspiration from satellite data at regional scales, and is used for atmospheric and hydrologic modeling, as well as ecosystem management. A scheme is proposed to estimate the DANR over large heterogeneous areas under clear-sky conditions using only remotely sensed data. The method was designed to overcome the dependence of DANR estimates on ground data, and to map spatially consistent and reasonably distributed DANR, by using various land and atmospheric data products retrieved from MODIS （Moderate Resolution Imaging Spectroradiometer） data. An improved sinusoidal model was used to retrieve the diurnal variations of downward shortwave radiation using a single instantaneous value from satellites. The downward shortwave component of DANR was directly obtained from this instantaneous value, and the upward shortwave component was estimated using satellite-derived albedo products. Four observations of air temperature from MOD07_L2 and MYD07_L2 data products were used to derive the downward longwave component of DANR, while the upward longwave component was estimated using the land surface temperature （LST） and the surface emissivity from MOD1 l_L2. Compared to in situ observations at the cropland and grassland sites located in Tongyu, northern China, the root mean square error （RMSE） of DANR estimated for both sites under clear-sky conditions was 37 W m-2 and 40 W m-2, respectively. The errors in estimation of DANR were comparable to those from previous satellite-based methods. Our estimates can be used for studying the surface radiation balance and evapotranspiration.

关键词： daily average net radiation satellite climate model four-component radiation surface radiation balance

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Strong heatwaves with widespread urban-related hotspots over Africa in 2019

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Atmospheric and Oceanic Science Letters 2022年第5期15卷 14-20页

作者： Eghosa Igun Xiyan Xu Yonghong Hu gensuo jia Key Laboratory of Regional Climate-Environment for East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Key Laboratory of Digital Earth Science Aerospace Information research InstituteChinese Academy of SciencesBeijingChina

2019 was one of the hottest years in recent decades,with widespread heatwaves over many parts of the world,including ***,as a developing and vulnerable region,the understanding of recent heatwave events in Africa is ***,the authors incorporated different climate datasets,satellite observations,and population estimates to investigate patterns and hotspots of major heatwave events over Africa in ***,2019 was one of the years that experienced the strongest heatwaves in terms of intensity and duration since 1981 in *** hotspots were clearly identified across western-coastal,northeastern,southern,and equatorial Africa,where major cities and human populations are *** proportion of urban agglomerations(population)exposed to extreme(99 th percentile)heatwaves in the Northern Hemisphere and Southern Hemisphere rose from 4%(5 million people)and 15%(17 million people),respectively,in the baseline period of 1981-2010 to36%(43 million people)and 57%(53 million people),respectively,in *** patterns and hotspots in 2019 were related to anomalous seasonal change in atmospheric circulation and above-normal sea surface *** adaptation to minimize susceptibility to the effects of heatwave events,the risks they pose in populated areas may increase rapidly in Africa.

关键词： Africa Temperature Heat wave Urban hotspots Population

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A global terrestrial ecosystem respiration dataset(2001-2010)estimated with MODIS land surface temperature and vegetation indices

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Big Earth Data 2020年第2期4卷 142-152页

作者： Jinlong Ai Shuyuan Xiao Hui Feng Huan Wang gensuo jia Yonghong Hu Department of Biology and Information Engineering Yiyang Vocational&Technical CollegeYiyangChina Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina

This paper describes how a validated semi-empirical,but physiologically based,remote sensing model-Ensemble_all-was upscaled using MODIS land surface temperature data(MOD11C2),enhanced vegetation indices(MOD13C1)and land-cover data(MCD12C1)to produce a global terrestrial ecosystem respiration data set(Reco)for January 2001-December *** temporal resolution of this data set is 1 month,the spatial resolution is 0.05°,and the range is from 55°S to 65°N and 180°W to 180°E(crop and natural vegetation mosaic is not included).After crossvalidating our data set using in-situ observations as well as Reco outputs from an empirical variable_Q10 model,a LPJ_S1 process model and a machine learning method model,we found that our data set performed well in detecting both temporal and spatial patterns in Reco’s simulation in most ecosystems across the *** data set can be found at http://***/10.11922/sciencedb.934.

关键词： Terrestrial ecosystem respiration MODIS data product up-scaling remote sensing model

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