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boreal SUMMER CLIMATOLOGY AND STANDARD DEVIATION IN GLOBAL LOW-FREQUENCY STREAMFUNCTION FIELDS AT 200 hPa

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Journal of Tropical Meteorology 2019年第2期25卷 153-161页

作者：季悦李艳杰吴志伟 Key Laboratory of Meteorology Disaster Ministry of Education (KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD) Nanjing University of Information Science and Technology State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Institute of Atmospheric Sciences Fudan University

Based on NCEP/NCAR DOE daily reanalysis dataset during 1980-2015, this study investigates the boreal summer climatology and standard deviation of streamfunction in different low frequency periods(including 10-30 days,30-60 days and more than 60 days) at 200 hPa. Distinctions in the characteristics in different periods are emphasized. It is found that the distribution of streamfunction on the timescale longer than 60 days is mainly zonal symmetric,accompanied by strong variability in the Northern Hemisphere subtropical jet streams. For the 10-30-day timescale, it reflects the zonal fluctuating structure in the middle and high latitudes and large variability in the Southern Hemisphere.Tropical quadrupole structure is observed on the 30-60-day timescale in climatology. Besides, a relative weak standard deviation is also found in this period. This work provides basic knowledge on climatology and variability in low-frequency streamfunction, which has not been fully illustrated in previous studies.

关键词： low-frequency streamfunction boreal summer climatology standard deviation

Tree diametric-species diversity is affected by human impact in old Scots pine dominated forest in boreal Fennoscandia

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Forest Ecosystems 2020年第1期7卷 92-103页

作者： Gonzalo de Quesada Timo Kuuluvainen Department of Forest Ecology University of HelsinkiP.O.Box 24FIN-00014 HelsinkiFinland

Background:Forest structural and compositional variability is of fundamental importance for forest ecosystem functioning and species diversity.The purpose of this research was to examine how human impact has affected the compositional-structural diversity of mature pine-dominated boreal forest in boreal Fennoscandia.For this a new approach was used,based on the classification of tree sizes by the diameter at breast height(dbh)and tree species,resulting in a new variable,the diametric-species,the variation of which describes the compositional-structural diversity of the forest.This variable was used to compare the structural-compositional diversity among three forest classes with different degree of human influence,using rarefaction as the main tool of analysis,complemented by analyses based on common diversity indices.Results:The results showed that the near-natural forest was the most diverse and the managed forest the least diverse.On the other hand,the diversity of near-natural and selectively logged forests were similar,suggesting that selectively logged forests are equal to the natural forest in their compositional-structural diversity.The analysis solely on tree species showed no significant differences among the forest classes of different human impact.The Shannon diversity index showed no significant difference between the forest classes for the diametric-species and tree species classifications only,but the Simpson index signaled a slight difference between the selectively logged and managed forest classes for the diametric-species classification.Furthermore,the Sorensen index detected a difference among forest classes in the diametric-species classification.Conclusions:Forest utilization had an adverse impact on forest compositional-structural diversity of mature Scots pine forests.The analysis also shows that the novel approach based on diametric-species classification could be a useful tool for forest diversity analysis and comparison,especially in species-poor forests such as the boreal forest.

关键词： Diametric-species boreal forest diversity Rarefaction analysis Human intervention Compositional-structural diversity

Carbon storage and net primary productivity in Canadian boreal mixedwood stands

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Journal of Forestry Research 2019年第5期30卷 1667-1678页

作者： Nicholas J.Payne D.Allan Cameron Jean-Denis Leblanc Ian K.Morrison Canadian Forest Service Great Lakes Forestry Centre

Canadian boreal mixedwood forests are extensive,with large potential for carbon sequestration and storage;thus,knowledge of their carbon stocks at different stand ages is needed to adapt forest management practices to help meet climate-change mitigation goals.Carbon stocks were quantified at three Ontario boreal mixedwood sites.A harvested stand,a juvenile stand replanted with spruce seedlings and a mature stand had total carbon stocks(±SE)of 133±13 at age 2,130±13 at age 25,and 207±15 Mg C ha^-1 at age 81 years.At the clear-cut site,stocks were reduced by about 40%or 90 Mg C ha^-1 at harvest.Vegetation held 27,34 and 62%of stocks,while detritus held 34,29 and 13%of stocks at age 2,25 and 81,respectively.Mineral soil carbon stocks averaged 51 Mg C ha^-1,and held 38,37 and 25%of stocks.Aboveground net primary productivity(±SE)in the harvested and juvenile stand was 2.1±0.2 and 3.7±0.3 Mg C ha^-1 per annum(p.a.),compared to 2.6±2.5 Mg C ha^-1 p.***.in the mature stand.The mature canopies studied had typical boreal mixedwood composition and mean carbon densities of 208 Mg C ha^-1,which is above average for managed Canadian boreal forest ecosystems.A comparison of published results from Canadian boreal forest ecosystems showed that carbon stocks in mixedwood stands are typically higher than coniferous stands at all ages,which was also true for stocks in vegetation and detritus.Also,aboveground net primary productivity was typically found to be higher in mixedwood than in coniferous boreal forest stands over a range of ages.Measurements from this study,together with those published from the other boreal forest stands demonstrate the potential for enhanced carbon sequestration through modified forest management practices to take advantage of Canadian boreal mixedwood stand characteristics.

关键词： Aboveground net primary productivity boreal mixedwood forest Carbon stocks Mixedwood stand management Stand age

Interhemispheric atmospheric mass oscillation and its relation to interannual variations of the Asian monsoon in boreal summer

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Science China Earth Sciences 2010年第9期53卷 1343-1350页

作者： LU ChuHan, GUAN ZhaoYong & CAI JiaXi Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric Sciences Nanjing University of Information Science & Technology Nanjing China

Using NCEP/NCAR reanalysis and precipitation records of Chinese stations, we have investigated the relationship of interhemispheric oscillation of air mass (IHO) with global lower-level circulation and monsoon anomalies in boreal summer. Our results show that the summer IHO explains a greater portion of variance in the abnormal distribution of atmospheric mass over 30°S-60°N as well as the Antarctic. The IHO strongly correlates to the variations of sea level pressure (SLP) in these regions. It is shown that IHO has some influences on both atmospheric mass transports and water vapor fluxes over 30°S-60°N in association with three anomalous cyclonic circulations over land areas of the eastern hemisphere, which is in close relation to the changes in summer monsoon intensity in eastern Asia and western Africa. Composites of summer rainfall anomalies in China for high and low IHO-index years indicate that the eastern Asian summer monsoon is more intense, with positive precipitation anomaly centers in northern and northeastern parts of China, as opposed to the negative center over the mid-lower reaches of the Yangtze River (MLRYR) in stronger IHO years. In weak IHO years, a feeble summer monsoon appears in eastern Asia, leading to positive center of precipitation anomalies displaced into the MLRYR. Furthermore, a teleconnection in wind fields between the western African and eastern Asian monsoon regions was observed in the middle and higher troposphere in the scenario of IHO. The anomalous cyclonic (anticyclonic) circulations along the path of this Africa-East Asia teleconnection were found to be just over the diabatic heating (cooling) centers, suggesting that diabatic forcings are responsible for the formation of this Africa-East Asia teleconnection.

关键词： interhemispheric oscillation Asian monsoon precipitation China boreal summer

Recent Strengthening of the Regional Hadley Circulation over the Western Pacific during boreal Spring

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Advances in Atmospheric Sciences 2019年第11期36卷 1251-1264页

作者： Ruping HUANG Shangfeng CHEN Wen CHEN Peng HU Bin YU Guangzhou Institute of Tropical and Marine Meteorology China Meteorological Administration Guangzhou 510080 China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China Climate Research Division Environment and Climate Change Canada Toronto ON M3H 5T4 Canada

Previous studies suggested that there are large discrepancies in the intensity trend of the zonally averaged Hadley circulation (ZAHC) among different reanalyses. As the land, ocean, and topography are not evenly distributed, the ZAHC may mask the regional variability. Changes in the regional HC have important implications for regional climate change. Here, we detect the long-term trend of the boreal spring regional Hadley circulation intensity over the western Pacific (WPHC) since 1979 in both hemispheres using six reanalysis datasets. Unlike the ZAHC, we find that the trend of the spring WPHC intensity is consistent among various reanalysis datasets. All reanalyses show pronounced strengthening trends for the WPHC in both the Northern and Southern Hemisphere, which may be partly attributable to the robust warming trends of sea surface temperature in the tropical western Pacific. The result could improve our understanding of Hadley circulation variability at the regional scale and has implications for regional climate changes.

关键词： regional Hadley circulation western Pacific long-term trend boreal spring

Integrating modelling and remote sensing to identify ecosystem performance anomalies in the boreal forest,Yukon River Basin,Alaska

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International Journal of Digital Earth 2008年第2期1卷 196-220页

作者： B.K.Wylie L.Zhang N.Bliss L.Ji L.L.Tieszen W.M.Jolly SAIC USGS Earth Resources Observation and Science(EROS)CenterSioux FallsSD 57198USA.Work performed under USGS contract 03CRCN0001 USGS EROS Center Sioux FallsSD 57198USA USDA Forest Service Fire Sciences LaboratoryMissoulaMT59808

High-latitude ecosystems are exposed to more pronounced warming effects than other parts of the globe.We develop a technique to monitor ecological changes in a way that distinguishes climate influences from disturbances.In this study,we account for climatic influences on Alaskan boreal forest performance with a datadriven model.We defined ecosystem performance anomalies(EPA)using the residuals of the model and made annual maps of EPA.Most areas(88%)did not have anomalous ecosystem performance for at least 6 of 8 years between 1996 and 2004.Areas with underperforming EPA(10%)often indicate areas associated with recent fires and areas of possible insect infestation or drying soil related to permafrost degradation.Overperforming areas(2%)occurred in older fire recovery areas where increased deciduous vegetation components are expected.The EPA measure was validated with composite burn index data and Landsat vegetation indices near and within burned areas.

关键词： climate change anomaly performance boreal Alaska Yukon River

Relationship between the Circumglobal Teleconnection and Silk Road Pattern over Eurasian continent

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Science Bulletin 2019年第6期64卷 374-376页

作者： Fuli Zhou Renhe Zhang Jinping Han Chinese Academy of Meteorological Sciences University of Chinese Academy of Sciences Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences Fudan University

During boreal summer, two remarkable upper-level wave trains over Eurasia were documented in literature, i.e., Circumglobal Teleconnection (CGT) and Silk Road Pattern (SRP). They are widely discussed because of their influences throughout the entire midlatitude Eurasia. SRP was defined by 200 hPa meridional winds [1]. Enomoto et al.[2] found that the wave train influenced the climate variation over Japan when they detected the mechanism of Bonin High, and then named it as "Silk Road Pattern". SRP has 3 prominent action centers, which are located in west-central Asia, Mongolia and the Far East, respectively [3].

关键词： During boreal summer remarkable upper-level located in west-central Asia

At what carbon price forest cutting should stop

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Journal of Forestry Research 2020年第3期31卷 713-727页

作者： Timo Pukkala University of Eastern Finland Yliopistokatu 780100 JoensuuFinland

T he carbon sink of boreal forests can be increased by paying forest landowners for carbon sequestration and taxing carbon releases. The aim of the study was to analyze the eff ect of carbon pricing on optimal forest management when forests are managed for maximal discounted benefi ts from timber production and carbon payments. A0.5% random sample of all private forest stands of Finland was used in the analyses(48,842 stands). Calculations were performed for a 100-year time horizon. It was assumed that the carbon balance(diff erence between sequestrated carbon and released carbon) in the forest(trees and soil) or the carbon balance of forestry(trees, soil and wood-based products)was subsidized(positive balance) or taxed(negative balance)by 0, 50, 100 or 150 € t-1, corresponding to CO2 prices of 0,13.6, 27.3 or 40.9 € t-1, respectively. The results showed that paying forest landowners 150 € t-1 of carbon sequestrated in forests would lead to the cessation of all cuttings everywhere in Finland for at least 100 years. In the northern part of the country, a carbon price of 100 € t-1 would be enough to make the no-cutting management economically optimal.A low carbon price had the highest relative impact(value ofincreased sequestration divided by the cost of carbon payments). The benefi t/cost ratio of carbon subsidies was higher in the northern part of boreal zone than in the southern parts. Subsidizing within-forest carbon sequestration by 50 € t-1 would increase the carbon sequestration of Finnish forestry by 50%, ranging from 36%(south Finland) to 116%(north Finland). A payment of 100 € t-1 or more would increase carbon sequestration by 70%, which is nearly the maximum possible increase that can be obtained by carbon subsidies.

关键词： boreal forest Carbon balance Carbon sequestration Carbon subsidies Optimal forest management

Estimating forest aboveground biomass using HJ-1 Satellite CCD and ICESat GLAS waveform data

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Science China Earth Sciences 2010年第S1期53卷 16-25页

作者： GUO ZhiFeng1,CHI Hong1,2 & SUN GuoQing1,3 1State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University,Institute of Remote Sensing Applications,Chinese Academy of Sciences,Beijing 100101,China 2Graduate University of Chinese Academy of Sciences,Beijing 100049,China 3Department of Geography University of Maryland,College Park,MD 20742,USA State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing China Graduate University of Chinese Academy of Sciences Beijing China Department of Geography University of Maryland College Park USA

The ecosystem in northeastern China and the Russian Far East is a hotspot of scientific research into the global carbon balance.Forest aboveground biomass(AGB) is an important component in the land surface carbon cycle.In this study,using forest inventory data and forest distribution data,the AGB was estimated for forest in Daxinganlin in northeastern China by combining charge-coupled device(CCD) data from the Small Satellite for Disaster and Environment Monitoring and Forecast(HJ-1) and Geoscience Laser Altimeter System(GLAS) waveform data from the Ice,Cloud and land Elevation Satellite(ICESat).The forest AGB prediction models were separately developed for different forest types in the research area at GLAS footprint level from GLAS waveform parameters and field survey plot biomass in the Changqing(CQ) Forest Center,which was calculated from forest inventory data.The resulted statistical regression models have a R2=0.68 for conifer and R2=0.71 for broadleaf forests.These models were used to estimate biomass for all GLAS footprints of forest located in the study area.All GLAS footprint biomass coupled with various spectral reflectivity parameters and vegetation indices derived from HJ-1 satellite CCD data were used in multiple regression analyses to establish biomass prediction models(R2=0.55 and R2=0.52 for needle and broadleaf respectively).Then the models were used to produce a forest AGB map for the whole study area using the HJ-1 data.Biomass data obtained from forest inventory data of the Zhuanglin(ZL) Forest Center were used as independent field measurements to validate the AGB estimated from HJ-1 CCD data(R2=0.71).About 80% of biomass samples had an error less than 20 t ha-1,and the mean error of all validation samples is 5.74 t ha-1.The pixel-level biomass map was then stratified into different biomass levels to illustrate the AGB spatial distribution pattern in this area.It was found that HJ-1 wide-swath data and GLAS waveform data can be combined to estimate forest biomass with good precision,and the b

关键词： Disaster and Environment Monitoring and Forecast Satellite ICESat GLAS waveform boreal forest forest aboveground biomass multiple linear regression