Influence of Feedbacks in the Climate–Energetics System on the Intensity of an Urban Heat Island

Both horizontal and vertical heat exchanges and feedbacks between air temperature and anthropogenic heat fluxes significantly affect the characteristics of the urban heat island (UHI). The UHI intensity depends, in particular, on the ratio between the scales L_A (area of anthropogenic forcing) and L_γ (distance passed by an air particle of the oncoming stably stratified flow before its temperature approaches air temperature within the UHI). Both advection and feedback effects may be estimated based on the equation for the local heat balance of the underlying surface. In this case, heat advection is taken into account by calculating temperatures individually for the atmospheric boundary layer and the surface of the urban canopy layer. The estimates show that the asymptotics of strong advection is more characteristic of a typical city. However, under weak winds, with consideration for the feedback between air temperature and anthropogenic heat flux, some deviations from this asymptotics are probable.     

Climate and carbon cycle variations in the 20th and 21st centuries in a model of intermediate complexity

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.     

台风"摩羯"(1814)残涡经渤海突然增强成因分析

利用气象常规资料、自动站资料、FY-4 可见光云图和 NCEP/NCAR 1毅伊1毅再分析资料,对 2018 年 14 号台风“摩羯”残涡经渤海增强前后热力、动力和水汽特征进行分析,结论如下：台风登陆北上后变性为温带气旋,其热力结构呈非对称分布,垂直风切变具有温带气旋特征,台风残涡入海后高空辐散、整层涡度、水汽通量和水汽通量速度等物理因子均明显增强。利用 Petterssen 气旋发展公式探讨入海增强原因,台风残涡入海前,温度平流对台风发展起主要作用,涡度平流对台风发展起抑制作用,台风残涡入海后,温度平流和涡度平流皆有利于台风残涡增强。非绝热加热作用在整个研究时段有利于台风发展,降水释放潜热加热对台风入海增强有正反馈作用,这种作用表现为一种突发性增大的特征。海洋平坦下垫面和适宜的海温是台风残涡入海增强的原因之一。     

Dependence of the Anthropogenic Heat Flux on Air Temperature (Using St. Petersburg as an Example)

Izvestiya, Atmospheric and Oceanic Physics - The anthropogenic heat flux associated with energy consumption for heating buildings has a significant impact on the heat balance of urbanized areas and...     

Estimating climate changes in the northern hemisphere in the 21st century under alternative scenarios of anthropogenic forcing

Possible changes in the climate characteristics of the Northern Hemisphere in the 21st century are estimated using a climate model (developed at the Obukhov Institute of Atmospheric Physics (OIAP), Russian Academy of Sciences) under different scenarios of variations in the atmospheric contents of greenhouse gases and aerosols, including those formed at the OIAP on the basis of SRES emission scenarios (group I) and scenarios (group II) developed at the Moscow Power Engineering Institute (MPEI). Over the 21st century, the global annual mean warming at the surface amounts to 1.2?C2.6°C under scenarios I and 0.9?C1.2°C under scenarios II. For all scenarios II, starting from the 2060s, a decrease is observed in the rate of increase in the global mean annual near-surface air temperature. The spatial structures of variations in the mean annual near-surface air temperature in the 21st century, which have been obtained for both groups of scenarios (with smaller absolute values for scenarios II), are similar. Under scenarios I, within the extratropical latitudes, the mean annual surface air temperature increases by 3?C7°C in North America and by 3?C5°C in Eurasia in the 21st century. Under scenarios II, the near-surface air temperature increases by 2?C4°C in North America and by 2?C3°C in Eurasia. An increase in the total amount of precipitation by the end of the 21st century is noted for both groups of scenarios; the most significant increase in the precipitation rate is noted for the land of the Northern Hemisphere. By the late 21st century, the total area of the near-surface permafrost soils of the land of the Northern Hemisphere decreases to 3.9?C9.5 10⁶ km² for scenarios I and 9.7?C11.0 × 10⁶ km² for scenarios II. The decrease in the area of near-surface permafrost soils by 2091?C2100 (as compared to 2001?C2010) amounts to approximately 65% for scenarios I and 40% for scenarios II. By the end of the 21st century, in regions of eastern Siberia, in which near-surface permafrost soils are preserved, the characteristic depths of seasonal thawing amount to 0.5?C2.5 m for scenarios I and 1?C2 m for scenarios II. In western Siberia, the depth of seasonal thawing amounts to 1?C2 m under both scenarios I and II.     

Model estimates of the eutrophication of the Baltic Sea in the contemporary and future climate

The St. Petersburg Baltic eutrophication model (SPBEM) is used to assess the ecological condition of the sea under possible changes in climate and nutrient loads in the 21st century. According to model estimates, in the future climate water quality will worsen, compared to modern conditions. This deterioration is stronger in the climate warming scenario with a stronger change in future near-surface air temperature. In the considered scenarios of climate change, climate warming will lead to an increase in the area of anoxic and hypoxic zones. Reduction of nutrient loading, estimated in accordance with the Baltic Sea Action Plan, will only be able to partially compensate for the negative effects of global warming.     

Current changes of the lower troposphere temperature in the Moscow region

Modern climatic changes for 1991–2013 in the lower 4-km layer of the atmosphere in the Moscow region are discussed based on long-term measurements using radiosondes in Dolgoprudny near Moscow and sensors installed on a high mast in Obninsk and on a television tower in Ostankino in Moscow. It is shown that at the end of the 20th century and the beginning of the 21st century the mean-annual air temperature at all heights from 2 to 4000 m increased by an average of 0.1°C per year. In recent years, the warming has slowed. Over the last two decades, long-term changes were multidirectional, depending on the season: warming in May–December, cooling in January–February, and no statistically significant changes in March and April. The probable reason for the temperature decrease in the middle of the cold period is changes in the large-scale atmospheric circulation during recent years (the negative phase of the North Atlantic Oscillation in early 2010s). In recent years, the Moscow region climate continentality has increased because of warming in summer and cooling in winter, despite the secular decreasing trend, which was noted before. Mean daily and annual warming rates in Dolgoprudny were higher than in Obninsk. The probable reason is the northward construction expansion and the strengthening of the Moscow heat island. The highest annual temperature amplitude is recorded at heights of 200–300 m.     

水面薄层热结构变化诱发机制的模拟研究──空气冷/暖平流效应

利用ＨＤＧ－高灵敏度红外测温仪和常规测试仪器在低温实验室的水槽中,对气温可控条件下模拟形成空气冷／暖平流流经水面过程中的静态水面薄层热结构进行了分层同步测量。数据分析表明,在空气暖平流过程中的静态水面薄层热气温骤增２１．５℃,水面皮温商步增加达１．５７℃,温度响应系数为＋０．０７３,这种温度应系数在升温吕过程中,其平均值为０．０４６;而在冷平流（降温）过程中,则为－０．０２２,个别情况下,皮温降低     

Simulation and prediction of climate changes in the 19th to 21st centuries with the Institute of Numerical Mathematics, Russian Academy of Sciences, model of the Earth’s climate system

This paper presents results from a simulation of climate changes in the 19th–21st centuries with the Institute of Numerical Mathematics Climate Model Version 4 (INMCM4) in the framework of the Coupled Model Intercomparison Project, phase 5 (CMIP5). Like the previous INMCM3 version, this model has a low sensitivity of 4.0 K to a quadrupling of CO₂ concentration. Global warming in the model by the end of the 21st century is 1.9 K for the RCP4.5 scenario and 3.4 K for RCP8.5. The spatial distribution of temperature and precipitation changes driven by the enhanced greenhouse effect is similar to that derived from the INMCM3 model data. In the INMCM4 model, however, the heat flux to the ocean and sea-level rise caused by thermal expansion are roughly 1.5 times as large as those in the INMCM3 model under the same scenario. A decrease in sea-ice extent and a change in heat fluxes and meridional circulation in the ocean under global warming, as well as some aspects of natural climate variability in the model, are considered.     

基于CMIP6气候变化情景下南极小须鲸(Balaenoptera bonaerensis)在宇航员海栖息地变化分析

南极小须鲸(Balaenopterabonaerensis)作为顶级捕食者,在南大洋生态系统中起着重要调节作用。目前对南极小须鲸的研究大多集中在捕食和季节性迁移上,在栖息地分布以及气候变化对栖息地影响方面研究亟待补充。基于MaxEnt模型和CMIP6的数据,分析了当前情形以及不同排放情景下,到21世纪中期和21世纪末期宇航员海南极小须鲸栖息地的分布和变化。研究结果表明,南极小须鲸主要分布在宇航员海的东部,当前的高度适生区占整个区域的13.96%。深度、海冰密集度和混合层深度最小值是南极小须鲸分布的主要影响因子,三者的累积贡献为60.5%。气候变化情景下南极小须鲸栖息地呈现缩小的趋势。高排放情景下南极小须鲸的栖息地面积减小更快,从21世纪中期到末期这个时期南极小须鲸的栖息地面积减小速率比从当前到21世纪中期快。到本世纪中期,所有情景下的宇航员海东部仍存在南极小须鲸的栖息地;到本世纪末,中排放情景和高排放情景下的宇航员海已不适合南极小须鲸生存,海冰密集度的减小是造成这一现象的主要原因。     

中国近海海平面变化半经验预测方法研究

由于用数值模式预测未来海平面变化存在很大的不确定性,而统计预测方法又通常不考虑相关物理过程,为此Rahmstorf通过建立海平面变化与全球气温变化的相关模型,提出了一个可行的半经验方法预测全球海平面.本文将Rahmstoff模型应用于中国近海,初步建立了一个在气候变暖背景下中国近海海平面长期变化的预测方法,预测结果表明...     

变暖背景下北极海冰减少在冬季北半球高纬大陆降雪增加中的作用

过去的几个冬季中,北美、欧洲、西伯利亚和东亚大部分地区经历了冷冬和强降雪,而这与北极海冰的快速减少有关。尽管北极海冰减少在冷冬和强降雪中的作用仍存在争议,但这种新兴的气候反馈在未来变暖背景下是否会持续仍值得关注。中等排放情境下的气候模式模拟结果揭示,欧洲东北部、亚洲中部北部、北美北部的冬季降雪增加会成为贯穿21世纪的一个稳健的特征。21世纪这些区域冬季降雪增加的主要原因是北极秋季海冰的减少（很大的外部强迫）,而冬季北极涛动的变化（北半球主要的自然变化形态）对降雪增加的作用很小。这一结果不仅体现在多模式平均上,而且每个单独模式的结果依然如此。我们认为海冰-降雪之间的强反馈作用可能已经出现,并且在接下来的几十年中这种强反馈作用可能会增强,北半球高纬地区的强降雪事件也会增加。     

Simulation of climate changes in the 20th–22nd centuries with a coupled atmosphere-ocean general circulation model

The results of numerical experiments with a coupled atmosphere-ocean general circulation model on the reproduction of climate changes during the 20th century and on the simulation of possible climate changes during the 21st–22nd centuries according to three IPCC scenarios of variations in the concentrations of greenhouse and other gases, as well as the results of the experiments with the doubled and quadruple concentrations of CO₂, are considered. An increase in the near-surface air temperature during the 20th century and the features of the observed climate changes, such as warming in 1940–1950 and its slowing down in 1960–1970, are adequately reproduced in the model. According to the model, the air-temperature increase during the 22nd century (as compared to the end of the 20th century) varies from 2 K for the most moderate scenario to 5 K for the warmest scenario. This estimate is somewhat lower than the expected warming averaged over the data of all models presented in the third IPCC report. According to model data, in the 22nd century, under all scenarios, at the end of summer, a complete or almost complete sea-ice melting will occur in the Arctic. According to the model, by the year 2200, the sea level will vary by 20 to 45 cm as compared to the level at the end of the 20th century.     

Interaction of the methane cycle and processes in wetland ecosystems in a climate model of intermediate complexity

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).     

CMIP5模式对南海SST的模拟和预估

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。     

Simulation evaluation and future prediction of the IPCC-AR4 GCMs on the extreme temperatures in China

On the basis of the temperature observations during 1961-2000 in China, seven coupled general circulation models＇ （GCMs） extreme temperature products are evaluated supplied by the Intergovernmental Panel on Climate Change＇ s 4th Assessment Report （IPCC-AR4）. The extreme temperature indices in use are frost days （FD）, growing season length （GSL）, extreme temperature range （ETR）, warm nights （TN90）, and heat wave duration index （HWDI）. Results indicate that all the seven models are capable of simulating spatial and temporal variations in temperature characteristics, and their ensemble acts more reliable than any single one. Among the seven models, GFDL-CM2.0 and MIROC3.2 performances are much better. Besides, most of the models are able to present linear trends of the same positive/negative signs as the observations but for weaker intensities. The simulation effects are different on a nationwide basis, with 110°N as the division, east （west） of which the effects are better （worse） and the poorer over the Qinghai-Tibetan Plateau in China. The predictions for the 21st century on emissions scenarios show that except decreases in the FD and ETR, other indices display significant increasing trend, especially for the indices of HWDI and TN90, which represent the notable extreme climate. This indicates that the temperature-related climate is moving towards the extreme. In the late 21st century, the GSL and TN90 （HWDI） increase most notably in southwest China （the Qinghai-Tibetan Plateau）, and the FD decrease most remarkably in the Qinghai-Tibetan Plateau, northwest and northeast of China. Apart from South China, the yearly change range of the extreme temperature is reduced in most of China.     

Hydrology and vegetation dynamics of the climate system of northern Eurasia and the Arctic basin

The dynamics of the climate and surface hydrology of northern Eurasia under the conditions of global climate changes is studied using coupled models of the atmospheric and oceanic general circulation. Feedbacks are assessed and analyzed for some parameters of the atmosphere and surface hydrology. The role of the biosphere (including the surface air layer, the vegetation layer, soil, and the hydrosphere) in the dynamics of the climate of the 21st century is studied. The features of the dynamics of the northern Atlantic seas during the periods corresponding to different phases of the North Atlantic Oscillation index are studied.     

Meridional mass and energy fluxes in the vicinity of the Arctic border

The air exchange between the Arctic and midlatitude regions is one of the processes forming the climate of the whole Northern Hemisphere. Analysis of the wind regime in the vicinity of the Arctic border (70° N) at the boundary between the 20th and 21st (1997–2004) centuries showed significant changes in the conditions of a meridional air transport between the Arctic and midlatitude regions as compared to the previous years (1960–1990). In this study, the wind fluxes of mass and heat (internal) and kinetic energies are estimated without consideration for turbulent and convective processes. The importance of spatial, seasonal, and interannual variations in wind velocity and air temperature in the formation of these fluxes is analyzed. It is shown that, during the period 1997–2004, an advective transport of energy from the northern latitudes occurred in the lower 6-km tropospheric layer at 70° N latitude over almost a whole year. Only in spring (April) did the wind fluxes bring heat energy from the south. The total amount of both heat and kinetic energies transported from the Arctic region in this way during a year is comparable to the mean amount of these energies contained in the whole atmosphere over the area bounded by 70° N latitude. The current spatial and temporal distributions of wind velocity and meridional mass and energy fluxes, which are presented in this study, may serve as additional information for interpreting data obtained from different on-site measurements in Arctic regions.     

Comparison of climatic efficiency of the mechanisms of land-surface albedo changes caused by land use

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.     

Probability distributions for cyclones and anticyclones from the NCEP/NCAR reanalysis data and the INM RAS climate model

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.