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1.
The climate model of intermediate complexity developed at the Oboukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), has been supplemented by a zero-dimensional carbon cycle model. With the carbon dioxide emissions prescribed for the second half of the 19th century and for the 20th century, the model satisfactorily reproduces characteristics of the carbon cycle over this period. However, with continued anthropogenic CO2 emissions (SRES scenarios A1B, A2, B1, and B2), the climate-carbon cycle feedback in the model leads to an additional atmospheric CO2 increase (in comparison with the case where the influence of climate changes on the carbon exchange between the atmosphere and the underlying surface is disregarded). This additional increase is varied in the range 67–90 ppmv depending on the scenario and is mainly due to the dynamics of soil carbon storage. The climate-carbon cycle feedback parameter varies nonmonotonically with time. Positions of its extremes separate characteristic periods of the change in the intensity of anthropogenic emissions and of climate variations. By the end of the 21st century, depending on the emission scenario, the carbon dioxide concentration is expected to increase to 615–875 ppmv and the global temperature will rise by 2.4–3.4 K relative to the preindustrial value. In the 20th–21st centuries, a general growth of the buildup of carbon dioxide in the atmosphere and ocean and its reduction in terrestrial ecosystems can be expected. In general, by the end of the 21st century, the more aggressive emission scenarios are characterized by a smaller climate-carbon cycle feedback parameter, a lower sensitivity of climate to a single increase in the atmospheric concentration of carbon dioxide, a larger fraction of anthropogenic emissions stored in the atmosphere and the ocean, and a smaller fraction of emissions in terrestrial ecosystems.  相似文献   

2.
ensemble simulations with the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS) climate model (CM) for the 21st century are analyzed taking into account anthropogenic forcings in accordance with the Special Report on Emission Scenarios (SRES) A2, A1B, and B1, whereas agricultural land areas were assumed to change in accordance with the Land Use Harmonization project scenarios. Different realizations within these ensemble experiments were constructed by varying two governing parameters of the terrestrial carbon cycle. The ensemble simulations were analyzed with the use of Bayesian statistics, which makes it possible to suppress the influence of unrealistic members of these experiments on their results. It is established that, for global values of the main characteristics of the terrestrial carbon cycle, the SRES scenarios used do not differ statistically from each other, so within the framework of the model, the primary productivity of terrestrial vegetation will increase in the 21st century from 74 ± 1 to 102 ± 13 PgC yr−1 and the carbon storage in terrestrial vegetation will increase from 511 ± 8 to 611 ± 8 PgC (here and below, we indicate the mean ± standard deviations). The mutual compensation of changes in the soil carbon stock in different regions will make global changes in the soil carbon storage in the 21st century statistically insignificant. The global CO2 uptake by terrestrial ecosystems will increase in the first half of the 21st century, whereupon it will decrease. The uncertainty interval of this variable in the middle (end) of the 21st century will be from 1.3 to 3.4 PgC yr−1 (from 0.3 to 3.1 PgC yr−1). In most regions, an increase in the net productivity of terrestrial vegetation (especially outside the tropics), the accumulation of carbon in this vegetation, and changes in the amount of soil carbon stock (with the total carbon accumulation in soils of the tropics and subtropics and the regions of both accumulation and loss of soil carbon at higher latitudes) will be robust within the ensemble in the 21st century, as will the CO2 uptake from the atmosphere only by terrestrial ecosystems located at extratropical latitudes of Eurasia, first and foremost by the Siberian taiga. However, substantial differences in anthropogenic emissions between the SRES scenarios in the 21st century lead to statistically significant differences between these scenarios in the carbon dioxide uptake by the ocean, the carbon dioxide content in the atmosphere, and changes in the surface air temperature. In particular, according to the SRES A2 (A1B, B1) scenario, in 2071–2100 the carbon flux from the atmosphere to the ocean will be 10.6 ± 0.6 PgC yr−1 (8.3 ± 0.5, 5.6 ± 0.3 PgC yr−1), and the carbon dioxide concentration in the atmosphere will reach 773 ± 28 ppmv (662 ± 24, 534 ± 16 ppmv) by 2100. The annual mean warming in 2071–2100 relatively to 1961–1990 will be 3.19 ± 0.09 K (2.52 ± 0.08, 1.84 ± 0.06 K).  相似文献   

3.
The climate model of intermediate complexity developed at the Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) is extended by a block for the direct anthropogenic sulfate-aerosol (SA) radiative forcing. Numerical experiments have been performed with prescribed scenarios of the greenhouse and anthropogenic sulfate radiative forcings from observational estimates for the 19th and 20th centuries and from SRES scenarios A1B, A2, and B1 for the 21st century. The globally averaged direct anthropogenic SA radiative forcing F ASA by the end of the 20th century relative to the preindustrial state is ?0.34 W/m2, lying within the uncertainty range of the corresponding present-day estimates. The absolute value of F ASA is the largest in Europe, North America, and southeastern Asia. A general increase in direct radiative forcing in the numerical experiments that have been performed continues until the mid-21st century. With both the greenhouse and the sulfate loadings included, the global climate warming in the model is 1.5–2.8 K by the end of the 21st century relative to the late 20th century, depending on the scenario, and 2.1–3.4 K relative to the preindustrial period. The sulfate aerosol reduces global warming by 0.1–0.4 K in different periods depending on the scenario. The largest slowdown (>1.5 K) occurs over land at middle and high latitudes in the Northern Hemisphere in the mid-21st century for scenario A2. The IAP RAS CM response to the greenhouse and the aerosol forcing is not additive.  相似文献   

4.
The climate model of the Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) has been supplemented with a module of soil thermal physics and the methane cycle, which takes into account the response of methane emissions from wetland ecosystems to climate changes. Methane emissions are allowed only from unfrozen top layers of the soil, with an additional constraint in the depth of the simulated layer. All wetland ecosystems are assumed to be water-saturated. The molar amount of the methane oxidized in the atmosphere is added to the simulated atmospheric concentration of CO2. A control preindustrial experiment and a series of numerical experiments for the 17th–21st centuries were conducted with the model forced by greenhouse gases and tropospheric sulfate aerosols. It is shown that the IAP RAS CM generally reproduces preindustrial and current characteristics of both seasonal thawing/freezing of the soil and the methane cycle. During global warming in the 21st century, the permafrost area is reduced by four million square kilometers. By the end of the 21st century, methane emissions from wetland ecosystems amount to 130–140 Mt CH4/year for the preindustrial and current period increase to 170–200 MtCH4/year. In the aggressive anthropogenic forcing scenario A2, the atmospheric methane concentration grows steadily to ≈3900 ppb. In more moderate scenarios A1B and B1, the methane concentration increases until the mid-21st century, reaching ≈2100–2400 ppb, and then decreases. Methane oxidation in air results in a slight additional growth of the atmospheric concentration of carbon dioxide. Allowance for the interaction between processes in wetland ecosystems and the methane cycle in the IAP RAS CM leads to an additional atmospheric methane increase of 10–20% depending on the anthropogenic forcing scenario and the time. The causes of this additional increase are the temperature dependence of integral methane production and the longer duration of a warm period in the soil. However, the resulting enhancement of the instantaneous greenhouse radiative forcing of atmospheric methane and an increase in the mean surface air temperature are small (globally < 0.1 W/m2 and 0.05 K, respectively).  相似文献   

5.
The atmosphere-ocean general circulation model with the carbon cycle is coupled to a model of methane evolution, in which methane sources in the soil of wetlands and methane evolution in the atmosphere are calculated. A numerical experiment on the simulation of climate and methane-cycle changes in 1860–2100 has been conducted with the model forced by methane emissions prescribed from scenario A1B. The distribution of the sources of methane from soil agrees with the available estimates and amounts to about 240 Mt/year in the 20th century. The methane flux from soil increases to 340 Mt/year by the end of the 21st century. The model adequately reproduces an increase in the atmospheric methane concentration from 800 ppb in 1860 to about 1800 ppb in 2000, but does not produce the observed stabilization of methane concentration in the early 21st century. By 2060, the methane concentration in the model attains 2700 ppb. The increase in atmospheric methane concentration is due mainly to anthropogenic emissions. A similar numerical experiment with fixed sources of methane from soil at the 1860–1900 level suggests that the maximum methane concentration in the model in this case could amount to 2400 ppb. A temperature increase at the end of the 21st century relative to the 19th century is 3.5° for a simulated change in the methane flux from soil and 0.25° less for a fixed methane flux.  相似文献   

6.
Assessments of future changes in the climate of Northern Hemisphere extratropical land regions have been made with the IAP RAS climate model (CM) of intermediate complexity (which includes a detailed scheme of thermo- and hydrophysical soil processes) under prescribed greenhouse and sulfate anthropogenic forcing from observational data for the 19th and 20th centuries and from the SRES B1, A1B, and A2 scenarios for the 21st century. The annual mean warming of the extratropical land surface has been found to reach 2–5 K (3–10 K) by the middle (end) of the 21st century relative to 1961–1990, depending on the anthropogenic forcing scenario, with larger values in North America than in Europe. Winter warming is greater than summer warming. This is expressed in a decrease of 1–4 K (or more) in the amplitude of the annual harmonic of soil-surface temperature in the middle and high latitudes of Eurasia and North America. The total area extent of perennially frozen ground S p in the IAP RAS CM changes only slightly until the late 20th century, reaching about 21 million km2, and then decreases to 11–12 million km2 in 2036–2065 and 4–8 million km2 in 2071–2100. In the late 21st century, near-surface permafrost is expected to remain only in Tibet and in central and eastern Siberia. In these regions, depths of seasonal thaw exceed 1 m (2 m) under the SRES B1 (A1B or A2) scenario. The total land area with seasonal thaw or cooling is expected to decrease from the current value of 54–55 million km2 to 38–42 in the late 21st century. The area of Northern Hemisphere snow cover in February is also reduced from the current value of 45–49 million km2 to 31–37 million km2. For the basins of major rivers in the extratropical latitudes of the Northern Hemisphere, runoff is expected to increase in central and eastern Siberia. In European Russia and in southern Europe, runoff is projected to decrease. In western Siberia (the Ob watershed), runoff would increase under the SRES A1B and A2 scenarios until the 2050s–2070s, then it would decrease to values close to present-day ones; under the anthropogenic forcing scenario SRES B1, the increase in runoff will continue up to the late 21st century. Total runoff from Eurasian rivers into the Arctic Ocean in the IAP RAS CM in the 21st century will increase by 8–9% depending on the scenario. Runoff from the North American rivers into the Arctic Ocean has not changed much throughout numerical experiments with the IAP RAS CM.  相似文献   

7.
Changes in ecosystem types, including situations when natural vegetation is replaced by agricultural lands, leads to surface albedo changes and the development of the corresponding short-wave radiative forcing (RF). This work analyzes ensemble numerical experiments with the climatic model (CM) of the Institute of Atmospheric Physics at the Russian Academy of Sciences (IAP RAS) for the 16th–21st centuries. The responses to changes in the contents of greenhouse gases and sulfate aerosols (tropospheric and stratospheric), in the solar constant, and in the land-surface albedo when natural vegetation is replaced by agricultural lands were modeled during these experiments. Different members of these ensemble experiments were obtained by varying the model parameters affecting the RF on the climate during land use: the albedo of agricultural lands was varied within the interval from 0.15 to 0.25 and the parameter controlling the efficiency of snow masking by tree vegetation was varied in the range from the absence of this effect to its maximally possible efficiency. It has been established that changes in surface albedo when natural vegetation is replaced by agricultural lands have the largest influence on the globally averaged annual mean RF at the top of the atmosphere, whereas the influence of snow masking on the RF is substantially less. This phenomenon is caused by the fact that snow masking by tree vegetation can take place only in winter in regions of temperate and high latitudes, when insolation is relatively low. A comparison of the spatial structure of the annual mean response of the surface temperature with the HadCRUT3v and GISS observational data makes it possible to narrow the admissible range of model parameter values. In particular, it can be inferred that the key parameter values which control the influence that land use has on the surface albedo in the IAP RAS CM are close to optimal. In addition, variations in these parameters do not lead to a significant influence of land use on climate change in the 21st century if the Land Use Harmonization (LUH) scenarios of changes in the area of agricultural lands are used: the uncertainty of the model response associated with the uncertainty of values of such controlling parameters in the 21st century does not exceed 0.1 K.  相似文献   

8.
Results from numerical experiments with an atmosphere-ocean general circulation model coupled to the carbon evolution cycle are analyzed. The model is used to carry out an experiment on the simulation of the climate and carbon cycle change in 1861–2100 under a specified scenario of the carbon dioxide emission from fossil fuel and land use. The spatial distribution of vegetation, soil, and oceanic carbon in the 20th century is generally close to available estimates from observational data. The model adequately reproduces the observed growth of atmospheric CO2 in the 20th century and the uptake of excess carbon by land ecosystems and by the ocean in the 1980s and 1990s. By 2100, the atmospheric CO2 concentration is calculated to reach 742 ppmv under emission and land-use scenario A1B. The feedback between climate change and the carbon cycle in the model is positive, with a coefficient close to the mean of all the current models. The ocean and land uptakes of the CO2 emission by 2100 in the model are 25 and 19%, which are also close to the mean over all models.  相似文献   

9.
Ensemble numerical experiments with the climate model of intermediate complexity developed at the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) are conducted to estimate the efficiency of controlled climate forcing (geoengineering) due to stratospheric sulfate aerosol (SSA) emissions in order to compensate for global warming under the SRES A1B anthropogenic emission scenario. Full (or even excessive) compensation for the expected anthropogenic warming in the model is possible with sufficiently intense geoengineering. For ensemble members with values of the governing parameters corresponding to those obtained for the Mt. Pinatubo eruption, global warming is reduced by no more than 0.46 K in the second half of the 21st century, with a residual rise in the global surface temperature T g comparative to 1961–1990 of 1.0–1.2 K by 2050 and 1.9–2.2 K by 2100. The largest reduction in global warming (with the other parameters of the numerical experiment being equal) is found not for a meridional distribution of SSA concentration peaked at low latitudes (despite the largest (in magnitude) global compensation instantaneous radiative forcing), but for a uniform horizontal aerosol distribution and for a distribution with the SSA concentration maximum in the middle and subpolar latitudes of the Northern Hemisphere. The efficiency of geoengineering in terms of T g in the second half of the 21st century between the most efficient and the least efficient meridional distributions of stratospheric aerosols differs by as much as one-third, depending on the values of other governing parameters. For meridional distributions of SSA concentration, which produce the largest deceleration of global warming, such a deceleration is regionally most pronounced over high- and subpolarlatitude land areas and in the Arctic. In particular, this is expressed in the smallest reduction in the sea-ice extent and permafrost area under climate warming in the model. The compensation forcing also decelerates a general increase in global annual precipitation P g during warming. The relative deceleration in precipitation increase is most pronounced in land regions outside the tropics, where a significant deficit in precipitation is currently observed. After the theoretical completion of geoengineering in the first or second decade, its temperature effect vanishes with an abrupt acceleration of global and regional surface warming. For individual members of the ensemble experiment, the global temperature change in this period is five times as large as that in the experiment without geoengineering and ten times as large regionally (in northeastern Siberia).  相似文献   

10.
A change in ecosystem types, such as through natural-vegetation-agriculture conversion, alters the surface albedo and triggers attendant shortwave radiative forcing (RF). This paper describes numerical experiments performed using the climate model (CM) of the Institute of Atmospheric Physics (IAP), Russian Academy of Sciences, for the 16th–21st centuries; this model simulated the response to a change in the contents of greenhouse gases (tropospheric and stratospheric), sulfate aerosols, solar constant, as well as the response to change in surface albedo of land due to natural-vegetation-agriculture conversion. These forcing estimates relied on actual data until the late 20th century. In the 21st century, the agricultural area was specified according to scenarios of the Land Use Harmonization project and other anthropogenic impacts were specified using SRES scenarios. The change in the surface vegetation during conversion from natural vegetation to agriculture triggers a cooling RF in most regions except for those of natural semiarid vegetation. The global and annual average RF derived from the IAP RAS CM in late 20th century is ?0.11 W m?2. Including the land-use driven RF in IAP RAS CM appreciably reconciled the model calculations to observations in this historical period. For instance, in addition to the net climate warming, IAP RAS CM predicted an annually average cooling and reduction in precipitation in the subtropics of Eurasia and North America and in Amazonia and central Africa, as well as a local maximum in annually average and summertime warming in East China. The land-use driven RF alters the sign in the dependence that the amplitude of the annual cycle of the near-surface atmospheric temperature has on the annually averaged temperature. One reason for the decrease in precipitation as a result of a change in albedo due to land use may be the suppression of the convective activity in the atmosphere in the warm period (throughout the year in the tropics) and the corresponding decrease in convective precipitation. In the 21st century, the effect that the land-use driven RF has on the climate response for scenarios of anthropogenic impact is generally small.  相似文献   

11.
The results are presented of statistical analysis of the data obtained from the 1980–2006 systematic measurements of the volume concentration of carbon dioxide in the atmospheric thickness over central Eurasia. The trends of both monthly and yearly means of CO2 concentration are determined. During these 26 years, the yearly mean concentration increased by ～42 ppm at a mean rate of (1.56 ± 0.18) ppm per year and reached ～382.7 ppm. General statistical characteristics are found. The distribution function of the monthly mean concentrations of CO2 is characterized by the presence of a second maximum and a bias of the principal mode toward large values, and the mean (over the measurement time) monthly concentration and the median almost coincide. The distribution function of the yearly mean concentrations of CO2 is close to a normal distribution, and the mean (over the measurement time) yearly concentration, the median, and the mode also coincide. The trends of short-and long-period variations in the carbon dioxide concentration and their possible relation to a number of geophysical phenomena are revealed. Spectral analysis of the measuring data on CO2 revealed oscillations with periods of 4, 6, 12, 15, 21, 29, 40, 53, 84, and 183 months. A statistical model with the parameters of these oscillations describes the experimental monthly mean concentrations of carbon dioxide with an rms deviation of 2.3 ppm (±0.6% of the mean over the entire period 361.9 ppm) and the yearly mean concentrations with an rms deviation of 0.9 ppm (～±0.3%).  相似文献   

12.
The current state of the simulation of sea ice cover as a component of new-generation global climate models is considered. Results from the model ensemble simulation of the observed world ocean ice cover, including its evolution in the 20th century, are analyzed, and projection of possible changes in the 21st century for three scenarios of anthropogenic forcing of the climate system are described. Unresolved problems and priorities for sea ice modeling are discussed.  相似文献   

13.
CMIP5模式对南海SST的模拟和预估   总被引：4，自引：1，他引：3  
分析了32个CMIP5模式对南海历史海表温度(SST)的模拟能力和不同排放情景下未来SST变化的预估。通过检验各气候模式对南海历史SST增温趋势和均方差的模拟,发现大部分模式都能较好地模拟出南海20世纪历史SST的基本特征和变化规律,但也有部分模式的模拟存在较大偏差。尽管这些模拟偏差较大的模式对SST多模式集合平均的影响不大,但会增加未来情景预估的不确定性。剔除15个模式后,分析了南海SST在RCP26、RCP45和RCP85三种排放情景下的变化趋势,发现在未来百年呈明显的增温趋势,多模式集合平均的增温趋势分别为0.42、1.50和3.30℃/(100a)。这些增温趋势在空间上变化不大,但随时间并不是均匀变化的。在前两种排放情景下,21世纪前期的增温趋势明显强于后期,而在RCP85情景下,21世纪后期的增温趋势强于前期。  相似文献   

14.
The IAP RAS CM (Institute of Atmospheric Physics, Russian Academy of Sciences, climate model) has been extended to include a comprehensive scheme of thermal and hydrologic soil processes. In equilibrium numerical experiments with specified preindustrial and current concentrations of atmospheric carbon dioxide, the coupled model successfully reproduces thermal characteristics of soil, including the temperature of its surface, and seasonal thawing and freezing characteristics. On the whole, the model also reproduces soil hydrology, including the winter snow water equivalent and river runoff from large watersheds. Evapotranspiration from the soil surface and soil moisture are simulated somewhat worse. The equilibrium response of the model to a doubling of atmospheric carbon dioxide shows a considerable warming of the soil surface, a reduction in the extent of permanently frozen soils, and the general growth of evaporation from continents. River runoff increases at high latitudes and decreases in the subtropics. The results are in qualitative agreement with observational data for the 20th century and with climate model simulations for the 21st century.  相似文献   

15.
2011年3月日本福岛核电站核泄漏在海洋中的传输   总被引：2，自引：0，他引：2  
使用全球版本的迈阿密等密度海洋环流模式对2011年3月日本福岛核电站泄漏在海洋中的传输以及扩散进行了数值模拟。数值模式中核废料(示踪物)排放情景采取等通量连续排放,排放时间从3月25日开始,分别持续20 d以及1 a,两种情形分别积分20 a。为了减少海洋环流年际变化带来的数值模拟的的不确定性,20 a的模式积分分别用2010年、1991-2011年、1971-1991年以及1951-1971年4个不同时段的NCEP/NCAR逐日再分析资料作为大气强迫场,因此每种排放情形包含4个数值试验。模拟结果的分析表明,不同核废料排放情景及其在不同时段大气资料对海洋模式的驱动下,模拟的示踪物总体的传输扩散路径(包括表层以及次表层)、传输速率以及垂直扩展的范围没有显著的差异。集合平均数值模拟的结果显示:在两种排放情景下,日本福岛核泄漏在海洋的传输路径受北太平洋副热带涡旋洋流系统主导,其传输路径首先主要向东,到达东太平洋后,再向南向西扩散至西太平洋,可能在10~15 a左右影响到我国东部沿海海域,且海洋次表层的传输信号比表层信号早5 a左右。通过进一步分析模式积分过程中最大示踪物浓度随时间变化发现,在积分第20 a(2031年3月),海洋表层和次表层浓度的最高值分别只有模式积分第一年浓度的0.1%和1%。在积分的20 a里,排放的核废料主要滞留在北太平洋海域(超过86%±1.5%的核废料在积分结束时,滞留在北太平洋),而在积分的前10 a(2021年之前),几乎所有的核废料滞留在北太平洋;在核废料的垂直分布上,主要集中在海洋表层至600 m的深度,在积分的20 a时间里,没有核废料信号扩散至1 000 m以下的深度。数值模拟的结果也表明核废料浓度减弱的强度以及演变的时间特征主要受洋流系统的影响,与排放源的排放时间长短关系不大。值得指出的是,更加准确地评估一个真实的核泄漏事故对海洋环境所造成的可能影响,还需要考虑大气中的放射性物质的沉降以及海洋生态对核物质的响应。  相似文献   

16.
使用全球版本的迈阿密等密度海洋环流模式对2011年3月日本福岛核电站泄漏在海洋中的传输以及扩散进行了数值模拟。数值模式中核废料(示踪物)排放情景采取等通量连续排放,排放时间从3月25日开始,分别持续20 d以及1 a,两种情形分别积分20 a。为了减少海洋环流年际变化带来的数值模拟的的不确定性,20 a的模式积分分别用2010年、1991-2011年、1971-1991年以及1951-1971年4个不同时段的NCEP/NCAR逐日再分析资料作为大气强迫场,因此每种排放情形包含4个数值试验。模拟结果的分析表明,不同核废料排放情景及其在不同时段大气资料对海洋模式的驱动下,模拟的示踪物总体的传输扩散路径(包括表层以及次表层)、传输速率以及垂直扩展的范围没有显著的差异。集合平均数值模拟的结果显示:在两种排放情景下,日本福岛核泄漏在海洋的传输路径受北太平洋副热带涡旋洋流系统主导,其传输路径首先主要向东,到达东太平洋后,再向南向西扩散至西太平洋,可能在10~15 a左右影响到我国东部沿海海域,且海洋次表层的传输信号比表层信号早5 a左右。通过进一步分析模式积分过程中最大示踪物浓度随时间变化发现,在积分第20 a(2031年3月),海洋表层和次表层浓度的最高值分别只有模式积分第一年浓度的0.1%和1%。在积分的20 a里,排放的核废料主要滞留在北太平洋海域(超过86%±1.5%的核废料在积分结束时,滞留在北太平洋),而在积分的前10 a(2021年之前),几乎所有的核废料滞留在北太平洋;在核废料的垂直分布上,主要集中在海洋表层至600 m的深度,在积分的20 a时间里,没有核废料信号扩散至1 000 m以下的深度。数值模拟的结果也表明核废料浓度减弱的强度以及演变的时间特征主要受洋流系统的影响,与排放源的排放时间长短关系不大。值得指出的是,更加准确地评估一个真实的核泄漏事故对海洋环境所造成的可能影响,还需要考虑大气中的放射性物质的沉降以及海洋生态对核物质的响应。  相似文献   

17.
Analysis of statistical characteristics of cyclones and anticyclones in the latitudinal belt between 20° and 80°N has been performed with the NCEP/NCAR reanalysis data and simulations with the general circulation climate model of the Institute of Numerical Mathematics of the Russian Academy of Sciences (INM RAS GCCM). The model results have been analyzed for the second half of the 20th century against the NCEP/NCAR reanalysis data and for the 21st century with the SRES-A2 anthropogenic scenario. Overall for the 20th century, no statistically significant changes in the number of cyclones and anticyclones are obtained from either the NCEP/NCAR reanalysis data [1] or from simulations with the INM RAS GCCM [2]. It is found that the total number of cyclones and anticyclones decreased in the 20th century as compared to the 21st century. It is shown that cumulative distributions of the number of cyclones and anticyclones by their intensities and areas have an exponential form from both the reanalysis data and the model simulations, although the corresponding exponents are different.  相似文献   

18.
A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios (called Rep- resentative Concentration Pathways, or RCPs). The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change (IPCC) for the Fifth Assessment Report (AR5). The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a (calculated by carbon) in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current (ACC) area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water (NADW), and also be transported to the north by the Antarctic Bottom Water (AABW) along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.  相似文献   

19.
What will happen to local record values of temperature and precipitation in a world with ongoing global warming? Here we first examine how many of the observed local temperature maxima of 1901–2006 occurred in the years 2001–2006 and compare the observations with model simulations. Then we study whether, and how soon, the models simulate the climate records of the 20th century to be broken in the ongoing 21st century.
In 27% of our analysis area, the highest annual mean temperatures of the whole period 1901–2006 were observed in 2001–2006. For the 22 climate models in our study, this fraction varies from 17% to 70%, with a multimodel mean of 40%. In simulations based on the SRES A1B emissions scenario, the highest annual mean temperature of the 20th century is exceeded on average in 99% of the global area by the year 2080. The same number for the highest (lowest) annual precipitation total is 60% (43%). Monthly and seasonal temperature and precipitation records are also analysed, and the geographical distributions of record value occurrence are related to the distributions of time mean climate change and magnitude of interannual variability.  相似文献   

20.
This paper is focused on the seasonality change of Arctic sea ice extent(SIE) from 1979 to 2100 using newly available simulations from the Coupled Model Intercomparison Project Phase 5(CMIP5).A new approach to compare the simulation metric of Arctic SIE between observation and 31 CMIP5 models was established.The approach is based on four factors including the climatological average,linear trend of SIE,span of melting season and annual range of SIE.It is more objective and can be popularized to other comparison of models.Six good models(GFDL-CM3,CESM1-BGC,MPI-ESM-LR,ACCESS-1.0,Had GEM2-CC,and Had GEM2-AO in turn) are found which meet the criterion closely based on above approach.Based on ensemble mean of the six models,we found that the Arctic sea ice will continue declining in each season and firstly drop below 1 million km~2(defined as the ice-free state) in September 2065 under RCP4.5 scenario and in September 2053 under RCP8.5 scenario.We also study the seasonal cycle of the Arctic SIE and find out the duration of Arctic summer(melting season) will increase by about 100 days under RCP4.5 scenario and about 200 days under RCP8.5 scenario relative to current circumstance by the end of the 21 st century.Asymmetry of the Arctic SIE seasonal cycle with later freezing in fall and early melting in spring,would be more apparent in the future when the Arctic climate approaches to "tipping point",or when the ice-free Arctic Ocean appears.Annual range of SIE(seasonal melting ice extent) will increase almost linearly in the near future 30–40 years before the Arctic appears ice-free ocean,indicating the more ice melting in summer,the more ice freezing in winter,which may cause more extreme weather events in both winter and summer in the future years.  相似文献   

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