未来气候情景下冬小麦潜在北移区农业气候资源变化特征

基于区域气候模式系统PRECIS输出的RCP4.5气候情景数据分析表明,相较于1981-2010年,至2071-2097年冬小麦种植北界将平均向北移动147.8 km,北移面积约1.86×105 km²。选取代表光、温、水资源的9项农业气候资源指标,探究未来情景下,2021-2097年冬小麦潜在北移区内农业气候资源变化特征,结果表明：(1)相较于基准时段(1961-1990年),未来潜在北移区内光照资源变化呈减少趋势;热量资源呈明显增加趋势,在21世纪末的30年,波动性加大;降水资源整体增加趋势不明显,但波动性亦呈现增大趋势。(2)未来潜在北移区内,2030T (2021-2050年)、2050T (2041-2070年)和2070T (2061-2090年)时段光照资源在研究区域的东北部减少幅度较大,而在西南部较小;热量资源在研究区域的北部增加比南部明显;降水资源则主要在研究区域的东北部增加明显。     

局地海表温度异常影响热带气旋路径的模拟研究

本文以热带气旋"鲇鱼"(2010)为例,利用WRF模式和"鲇鱼"移动路径上不同的局地海表温度(SST)强迫进行了敏感性数值模拟。控制试验(CTRL)采用NCEP的SST强迫,敏感性试验分别在"鲇鱼"登陆菲律宾前的路径上增加(EXP1)和减小(EXP2)SST。结果表明:CTRL试验模拟的热带气旋路径与实况非常一致,EXP1试验模拟的热带气旋路径提前转向,移动路径偏东,EXP2试验模拟的热带气旋路径转向滞后,且移动路径偏西。对SST异常导致热带气旋路径出现差异的原因分析发现,热带气旋在吕宋岛东侧经过异常暖SST海面时,热带气旋强度增强,产生异常的正涡度平流,且500 h Pa以上凝结潜热释放增强副热带高压敏感区出现温度场的正异常,500h Pa以下水凝物的混合和蒸发作用增强造成副热带高压敏感区温度场的负异常,加之正的异常涡度平流和异常的上暖下冷温度场配置使得500 h Pa位势高度降低,副热带高压强度减弱,副热带高压西伸范围减小,导致热带气旋提前向北转向,移动路径偏东。反之,当热带气旋在吕宋岛东侧经过异常冷SST海面时,副热带高压西伸范围扩大,导致热带气旋向北转向滞后,路径偏西。     

Assessment of possible expansion of the climatic range of Italian locust (<Emphasis Type="Italic">Calliptamus italicus</Emphasis> L.) in Russia in the 21st century at simulated climate changes

The areas of distribution, high pest damage, and mass reproduction of Italian locust are mainly limited by climatic factors. It is demonstrated that under conditions of the RCP4.5 moderate scenario of anthropogenic impact on the global climate system in Russia in the 21st century the climatic range of Italian locust will be expanded mainly northward and, to a smaller extent, eastward. The expansion of the range by the middle of the 21st century as compared with the end of the 20th century will be more significant that at the end of the 21st century versus its middle.     

Increasing Aridity is Enhancing Silver Fir Abies Alba Mill.) Water Stress in its South-Western Distribution Limit

Tree populations located at the geographical distribution limit of the species may provide valuable information about the response of tree growth to climate warming across climatic gradients. Dendroclimatic information was extracted from a network of 10 silver-fir (Abies alba) populations in the south-western distribution limit of the species (Pyrenees, NE Iberian Peninsula). Ring-width chronologies were built for five stands sampled in mesic sites from the Main Range in the Pyrenees, and for five forests located in the southern Peripheral Ranges where summer drought is more pronounced. The radial growth of silver-fir in this region is constrained by water stress during the summer previous to growth, as suggested by the negative relationship with previous September temperature and, to a lesser degree, by a positive relationship with previous end of summer precipitation. Climatic data showed a warming trend since the 1970s across the Pyrenees, with more severe summer droughts. The recent warming changed the climate-growth relationships, causing higher growth synchrony among sites, and a higher year-to-year growth variation, especially in the southernmost forests. Moving-interval response functions suggested an increasing water-stress effect on radial growth during the last half of the 20th century. The growth period under water stress has extended from summer up to early autumn. Forests located in the southern Peripheral Ranges experienced a more intense water stress, as seen in a shift of their response to precipitation and temperature. The Main-Range sites mainly showed a response to warming. The intensification of water-stress during the late 20th century might affect the future growth performance of the highly-fragmented A. alba populations in the southwestern distribution limit of the species.     

2005—2010年台风突变路径的预报误差及其环流背景

本文主要分析了2005-2010年西北太平洋上台风突变路径的预报误差及其相联系的环流形势.通过分析北折和西折两种突变路径发现,中央气象台对西折突变路径的24和48 h预报接近平均预报水平;北折突变路径突变时刻,24 h预报的距离误差达到145.6 km,比平均预报误差增加了29.3％,48 h预报的距离误差达317.3 km,比平均预报误差增加了68.3％.从突变路径的物理机制方面分析突变路径预报的难点.将台风附近气流分解成低频和高频两部分,合成分析发现两类突变路径的风场区别不仅表现在低频尺度上副热带高压的西伸程度,还表现在天气尺度上台风附近的风场分布.     

Relationship between projected changes in future climatic suitability and demographic and functional traits of forest tree species in Spain

The response of plant species to future climate conditions is probably dependent on their ecological characteristics, including climatic niche, demographic rates and functional traits. Using forest inventory data from 27 dominant woody species in Spanish forests, we explore the relationships between species characteristics and projected changes in their average climatic suitability (occurrence of suitable climatic conditions for a species in a given territory) obtained by empirical niche-based models, under a business-as-usual climate change scenario (A1, HadCM3, 2001–2100). We hypothesize that most species will suffer a decline in climatic suitability, with a less severe for species (i) currently living in more arid climates or exhibiting a broader current climatic niche; (ii) with higher current growth rates; (iii) with functional traits related to resistance to water deficits. The analysis confirm our hypothesis since apart from a few Mediterranean species, most species decrease their climatic suitability in the region under future climate, characterized by increased aridity. Also, species living in warmer locations or under a wider range of climatic conditions tend to experience less decrease in climatic suitability. As hypothesized, a positive relationship was detected between current relative growth rates and increase in future climatic suitability. Nevertheless, current tree mortality did not correlate with changes in future climatic suitability. In contrast with our hypothesis, functional traits did not show a clear relationship with changes in climate suitability; instead species often presented idiosyncratic responses that, in some cases, could reflect past management. These results suggest that the extrapolation of species performance to future climatic scenarios based on current patterns of dominance is constrained by factors other than species autoecology, particularly human activity.     

T213与T639模式热带气旋预报误差对比

应用国家气象中心全球谱模式T213L31(简称T213) 及其升级版本T639L60(简称T639) 对2009—2010年西北太平洋热带气旋数值预报的结果进行对比。结果表明:T213与T639模式24～120 h预报平均距离误差基本相近,但由于T639模式分辨率较高,T639模式的热带气旋强度预报明显好于T213模式。从分类误差来看,T639模式对于西北行登陆及转向热带气旋的路径预报好于T213模式,但对西行及北上热带气旋预报误差偏大。对于异常路径热带气旋预报,T639模式能较好预报环流形势的突然调整,对路径突变的热带气旋预报比T213模式有明显优势;从登陆类热带气旋预报的移向误差来看,T213模式存在东北偏北向系统性偏差,T639模式存在东北偏东向系统性偏差。     

Taking the Pulse of Mountains: Ecosystem Responses to Climatic Variability

An integrated program of ecosystem modeling and field studies in the mountains of the Pacific Northwest (U.S.A.) has quantified many of the ecological processes affected by climatic variability. Paleoecological and contemporary ecological data in forest ecosystems provided model parameterization and validation at broad spatial and temporal scales for tree growth, tree regeneration and treeline movement. For subalpine tree species, winter precipitation has a strong negative correlation with growth; this relationship is stronger at higher elevations and west-side sites (which have more precipitation). Temperature affects tree growth at some locations with respect to length of growing season (spring) and severity of drought at drier sites (summer). Furthermore, variable but predictable climate-growth relationships across elevation gradients suggest that tree species respond differently to climate at different locations, making a uniform response of these species to future climatic change unlikely. Multi-decadal variability in climate also affects ecosystem processes. Mountain hemlock growth at high-elevation sites is negatively correlated with winter snow depth and positively correlated with the winter Pacific Decadal Oscillation (PDO) index. At low elevations, the reverse is true. Glacier mass balance and fire severity are also linked to PDO. Rapid establishment of trees in subalpine ecosystems during this century is increasing forest cover and reducing meadow cover at many subalpine locations in the western U.S.A. and precipitation (snow depth) is a critical variable regulating conifer expansion. Lastly, modeling potential future ecosystem conditions suggests that increased climatic variability will result in increasing forest fire size and frequency, and reduced net primary productivity in drier, east-side forest ecosystems. As additional empirical data and modeling output become available, we will improve our ability to predict the effects of climatic change across a broad range of climates and mountain ecosystems in the northwestern U.S.A.     

Model Computations on the Effects of Elevating Temperature and Atmospheric CO2 on the Regeneration of Scots Pine at the Timber Line in Finland

Based on model computations, the regeneration of Scots pine (Pinus sylvestris L.) was studied at the northern timber line in Finland (70°N) in relation to elevating temperature and atmospheric CO₂. If a transient increase of 4°C was assumed during the next 100 years, the length of growing season increased from the current 110–120 days to 150–160 days. This was associated with ca. 5°C increase in the soil temperature over June–August with larger variability in temperature and deeper freezing of the soil due to the reduced depth and duration of the snow cover. At the same time, the moisture content of the surface soil decreased ca. 10% and was more variable, due to less infiltration of water into the soil as a consequence of the enhanced evapotranspiration and deeper freezing of the soil. The temperature elevation alone, or combined with elevating CO₂, increased flowering and the subsequent seed crop of Scots pine with a decrease in the frequency of zero crops. In both cases, temperature elevation substantially increased the success of regeneration in terms of the number of seedlings produced after each seed crop. The increasing number of mature seeds was mainly responsible for the enhanced regeneration, but increasing soil temperature also increased the success of regeneration. The soil moisture was seldom limited for seed germination. In terms of the density of seedling stands, and the height and diameter growth of the seedlings, the establishment of a seedling stand was substantially improved under the combined elevation of temperature and CO₂ in such a way that the temperature increased the number of mature seeds and enhanced germination of seeds and CO₂ increased seedling growth. Even under the changing climatic conditions, however, the growth of the seedling stands was slow, which indicated that the northward advance of the timber line would probably be very slow, even though regeneration was no longer a limiting factor.     

Changes to the Natural Regional Boundaries in China During 1961-2007

Daily temperature data from 599 stations across China for the years 1961 to 2007 were used to analyze the changes in the natural regional boundaries.The results show that the accumulated temperature ≥ 10℃ and its duration changed dramatically from the end of 1990s to the early 21st century.The amplitude of natu-ral regional boundaries was greater in the 21st century than it was in the 20th century.In the eastern region of China,the climatic zones were migrating generally northward,with the northern edge of the subtropical zone and the eastern section of the warm temperate zone showing an obvious northward shift of up to 1 3° of lati-tude.The climatic zones moved south in the Qing-hai-Tibet Plateau,western Inner Mongolia,and some ar-eas of western Xinjiang,and slightly to the north in other parts of the western region.     

Impact of vegetation feedback on the mid-Pliocene warm climate

Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future.In this study,we conducted several simulations to analyze vegetation feedback during the mid-Pliocene warm period.The results indicate that the main features of vegetation change in the mid-Pliocene were a northward shift of needleleaf tree,an expansion of broadleaf tree and shrub,and a northward expansion of grass,as compared to the pre-industrial period.The global annual mean warming ratio caused by vegetation feedback was 12.1％,and this warming ratio was much larger in northern middle and high latitudes.The warming caused by vegetation change was directly related to the surface albedo change and was further amplified by snow/sea ice-albedo feedback.     

Modeling the Effects of Global Climatic Change at the Ecotone of Boreal Larch Forest and Temperate Forest in Northeast China

The dynamics of the forest at the ecotone of the boreal forest and temperate forest in Northeast China were simulated using the adapted gap model BKPF under global climatic change (GFDL scenario) and doubled CO₂ concentrations at 50 years in the future. The response of tree species and species with similar biological characteristics under global climate change and double CO₂ concentrations were based on biophysical limits of the tree species in the area and their biological competition. The results showed that after 50 years the stand density and LAI (leaf area index) of the forest growing from a clear-cut would not be significantly different from those under current conditions. Stand productivity would increase about 7%, and stand aboveground biomass would increase 15%. However, the stand density of the current mature forest would be reduced by more than 20%. The stand would be dominated by Quercus mongolica Fisch., Populus davidiana Dode., Betula spp. and other broadleaved tree species, and Quercus mongolica would account for about 50% of the total density. The stand biomass would be reduced by more than 90%. Quercus mongolica would comprise about 57% of the total stand biomass. The stand productivity would not change significantly, but it would be comprised mainly of Quercus mongolica, Populus davidiana, Betula spp. The current stand height would decrease slightly. The stand LAI would decline dramatically, moreover, Quercus mongolica would comprise about 50% of the stand LAI.     

Climatic fluctuations on the century time scale: A review of high-resolution proxy data and possible mechanisms

We review the century time scale climatic variability that is observed in high-resolution proxy data records covering the past 10 000 yr. Cyclic variations with time scales ranging from 50 to 400 yr occur in oxygen isotope ratios derived from ice cores, tree-ring index series, pollen records and sea-ice extents. Century time scale cycles can also be identified in some biological and historical records and in long-term instrumental observations. In order to appreciate the century scale cycles in the context of climatic variability in general, a brief survey of all climatic time scales is presented.The traditional interpretation that decadal-to-century scale fluctuations in the climate system are externally forced, e.g. by variations in solar properties, is questioned. A different mechanism for these fluctuations is proposed on the basis of recent findings of numerical models of the ocean's thermohaline circulation. The results indicate that this oceanic circulation exhibits natural variability on the century time scale which produces oscillations in the ocean-to-atmosphere heat flux. Although global in extent, these fluctuations are largest in the Atlantic Ocean.     

Sensitivity of boreal forests to possible climatic warming

General circulation models indicate substantial CO₂ warming in high latitudes. In these regions, which include the boreal coniferous forests, the activity of ecosystems is largely controlled by temperature. The effective temperature sum (degree-days) is used in this study for describing the regional variability in the productivity of boreal ecosystems. Although the concept is simple, it takes into account two basic factors: the length of the growing season and the day-to-day level of activity of the ecosystem. This study examines which areas in the boreal coniferous forests would be most sensitive to a possible climatic warming. The data used in the study are for Finland.A regression is estimated between regional forest growth rate and effective temperature sum. A climatic warming is assumed and the corresponding growth response is calculated, using the regression, for northern and southern areas, and for maritime and continental areas. The response is expressed in terms of (i) absolute increase in growth (grams per m² per year) and (ii) relative increase in growth. The results indicate that a given climatic warming would yield the greatest absolute increase in growth in warm (i.e. southern) and maritime parts of the biome. In terms of the relative growth response the sensitivity would increase northward and toward maritime areas.     

春季黑潮延伸体海洋锋区经向位移与东亚大气环流的关系

采用高分辨率的海表温度资料定义了春季黑潮延伸体北侧海洋锋区的南北位置,并采用EOF分析、相关分析、合成分析、带通滤波等方法,探讨了其南北向位置变动与高空急流、风暴轴以及后期东亚降水之间的关系。结果表明,春季黑潮延伸体北侧海洋锋区位置的南北变动存在明显的年际、年代际变化,其与6月东亚高空急流、太平洋区域风暴轴的南北位置具有很好的对应关系。当春季黑潮延伸体海洋锋区偏北时,6月东亚高空急流、太平洋区域风暴轴偏北,反之亦然。进一步的研究还表明,春季黑潮延伸体海洋锋区经向位置的变动可通过影响东亚大气环流对6月东亚地区的降水产生影响,黑潮延伸体海洋锋区偏北(南)年,6月雨带有显著的北(南)移。     

Modelling Regional Climate Change Effects On Potential Natural Ecosystems in Sweden

This study aims to demonstrate the potential of a process-based regional ecosystem model, LPJ-GUESS, driven by climate scenarios generated by a regional climate model system (RCM) to generate predictions useful for assessing effects of climatic and CO₂ change on the key ecosystem services of carbon uptake and storage. Scenarios compatible with the A2 and B2 greenhouse gas emission scenarios of the Special Report on Emission Scenarios (SRES) and with boundary conditions from two general circulation models (GCMs) – HadAM3H and ECHAM4/OPYC3 – were used in simulations to explore changes in tree species distributions, vegetation structure, productivity and ecosystem carbon stocks for the late 21st Century, thus accommodating a proportion of the GCM-based and emissions-based uncertainty in future climate development. The simulations represented in this study were of the potential natural vegetation ignoring direct anthropogenic effects. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among seven major tree species of natural Swedish forests. All four climate scenarios were associated with an extension of the boreal forest treeline with respect to altitude and latitude. In the boreal and boreo-nemoral zones, the dominance of Norway spruce and to a lesser extent Scots pine was reduced in favour of deciduous broadleaved tree species. The model also predicted substantial increases in vegetation net primary productivity (NPP), especially in central Sweden. Expansion of forest cover and increased local biomass enhanced the net carbon sink over central and northern Sweden, despite increased carbon release through decomposition processes in the soil. In southern Sweden, reduced growing season soil moisture levels counterbalanced the positive effects of a longer growing season and increased carbon supply on NPP, with the result that many areas were converted from a sink to a source of carbon by the late 21st century. The economy-oriented A2 emission scenario would lead to higher NPP and stronger carbon sinks according to the simulations than the environment-oriented B2 scenario.     

The Great Lakes diversion at Chicago and its implications for climate change

In 1900 the city of Chicago began diverting sizable amounts of water from Lake Michigan to move its sewage down the Illinois River. This diversion launched a series of continuing legal controversies involving Illinois as a defendant against claims by the federal government, various lake states, and Canada who wanted the diversion stopped or drastically reduced. During the past 96 years extended dry periods have lowered the lake levels. Using these dry periods as surrogates for future conditions, their effects on the past controversies were examined as analogs for what might occur as a result of climate change from an enhanced Greenhouse effect. The results reveal that changing socioeconomic factors including population growth will likely cause increased water use, and Chicago will seek additional water from the Great Lakes. New priorities for water use will emerge as in the past. Drier future conditions will likely lead to enhanced diversions from the Great Lakes to serve interests in and outside the basin. Future lower lake levels (reflecting a drier climate) will lead to conflicts related to existing and proposed diversions, and these conflicts would be exacerbated by the consequences of global warming. In any event, a warmer, drier climatic regime will challenge existing laws and institutions for dealing with Great Lakes water issues.     

二维能量平衡模式对若干气候问题的研究

Based on a two-dimensional energy balance model, the studies on some climatic issues such as the re- lationship between ice cap latitude and solar constant, desertifieation, and the warming effect of carbon dioxide, have been reviewed and discussed. The phenomenon that a fixed solar constant might correspond to different equilibrium ice cap latitudes is determined by the continuity of albedo distribution. The disconti- nuity in albedo distribution increases the number of equilibrium ice cap latitudes. Desert would expand both northward and southward when desert surface albedo is increasing. This would deteriorate the ecological environment in border regions, and then threaten the existence of local inhabitants. Melting of the polar ice would not be accelerated, with increasing carbon dioxide concentration. The ice cap latitude would move northward slowly, with some “hiatus” periods, under the slowly increasing global average surface tempera- ture. According to the current research, future development of the two-dimensional energy balance model and possible progress are also forecasted.     

Climatic trends from isotopic records of tree rings: The past 100–200 years

There has been a great deal of discussion about global warming from accumulation of anthropogenic greenhouse gases in the atmosphere (Houghton et al., 1990). Relatively less attention has been paid to spatial and/or temporal climatic variations that may be associated with a warmer climate (Rind et al., 1989) or with anthropogenic activities (Schneider, 1994). In this article, we show that an increase in climatic variability may have started. Fourteen isotopic time series of tree rings are presented. These trees were randomly collected from world-wide locations and cover time periods of 120 to over 200 years. The isotopic records show increasing D values that suggest a consistent and progressive warming occurred in the 19th century in all locations where the trees were sampled. The rate of warming is greater at relatively cold locations than at warm locations with two exceptions. The records also suggest greater climatic variations both temporally and spatially in the 20th century than in the 19th century.     

Decreasing teleconnections with inter-site distance in monthly climatic data and tree-ring width networks in a mountainous Alpine area

Summary The similarities in time series recorded at sites which are distant from each other are called teleconnections. In this paper, the loss of such correlations with inter-site distance was investigated for both climatic and dendrochronological data sets, with 70 tree-ring chronologies. A dense network of weather stations was studied in the southeastern French Alps, covering complex climatic gradients over three departments. 78 sites with precipitation data (with a total of 48 756 monthly values), and 48 stations that recorded temperature (with 20 722 monthly mean values) were analysed. In the same area, four coniferous species (mountain pine and stone pine, European larch and Norway spruce) provided 37 ring-width chronologies for high elevation sites near the timberline. Both silver fir and Norway spruce provided a second tree-ring chronology network for 33 different sites at lower elevations. The teleconnections between precipitation series were found to be higher than those observed for temperature over short distances, but the maximum threshold distance was lower (193 km) compared to a positive correlation distance that exceeds 500 km for temperature. The maximum temperatures had stronger teleconnections than minimum values (522 km versus 476 km), since the latter are linked more with other site factors, such as slope, exposure and local topography. As expected, the tree-ring chronologies showed weaker teleconnections than the climatic series, with a threshold distance of 374 km obtained for all high elevation forests. The coniferous species with high intra-specific teleconnections over large distances were, in decreasing importance, Pinus uncinata (> 500 km), Picea abies (477 km), Pinus cembra (over 254 km) and Larix decidua (over 189 km only). The two former species showed the highest intra-specific correlations (with mean correlation R=0.625 and 0.666). The dendrochronological teleconnections were found to have a extent lesser for trees species that depend on rainfall (such as larch, and stone pine). They are enhanced, however, for temperature sensitive species such as spruce and mountain pine (a drought resistant tree). Therefore, these two latter conifers appear to be especially suitable for climatic reconstruction over large distances in mountainous areas. However, teleconnections within silver fir (Abies alba) and spruce chronologies were sharply reduced (over 131 km and 135 km) in lower elevation forests, underlining the interest of timberline forests for dendroclimatology. A better knowledge of the spatial correlations in climatic series and ring-width data may enable the optimisation of weather station networks. It may also permit a better choice of weather stations used for dendroclimatology, either for tree-ring and climate relationship calibration or for climate reconstructions. In dendrochronology, wood dating also requires the knowledge of to what extent remote ring-width chronologies can be used. Received September 11, 2000 Revised March 26, 2001