盘锦湿地芦苇群落土壤呼吸作用动态及其影响因子分析

采用LI-6400-09土壤呼吸室对盘锦湿地芦苇群落土壤呼吸作用,于2004年7月—2005年12月进行连续野外观测。结果表明:非淹水状态下,湿地芦苇群落土壤呼吸作用具有明显的日变化和季节变化特征;淹水状态下,湿地芦苇群落土壤呼吸作用接近于0。2005年潮汐造成的洪水减少了2/3的土壤呼吸作用。2004年和2005年芦苇群落土壤呼吸作用最大值都出现于洪水退去后。影响湿地芦苇群落土壤呼吸作用空间异质性的主导因子是生物因子,而在同一时间影响湿地芦苇群落土壤呼吸作用的主导因子是温度和水分。     

The role of terrestrial snow cover in the climate system

Snow cover is known to exert a strong influence on climate, but quantifying its impact is difficult. This study investigates the global impact of terrestrial snow cover through a pair of GCM simulations run with prognostic snow cover and with all snow cover on land eliminated (NOSNOWCOVER). In this experiment all snowfall over land was converted into its liquid–water equivalent upon reaching the surface. Compared with the control run, NOSNOWCOVER produces mean-annual surface air temperatures up to 5 K higher over northern North America and Eurasia and 8–10 K greater during winter. The globally averaged warming of 0.8 K is one-third as large as the model’s response to 2 × CO₂ forcing. The pronounced surface heating propagates throughout the troposphere, causing changes in surface and upper-air circulation patterns. Despite the large atmospheric warming, the absence of an insulating snow pack causes soil temperatures in NOSNOWCOVER to fall throughout northern Asia and Canada, including extreme wintertime cooling of over 20 K in Siberia and a 70% increase in permafrost area. The absence of snow melt water also affects extratropical surface hydrology, causing significantly drier upper-layer soils and dramatic changes in the annual cycle of runoff. Removing snow cover also drastically affects extreme weather. Extreme cold-air outbreaks (CAOs)—defined relative to the control climatology—essentially disappear in NOSNOWCOVER. The loss of CAOs appears to stem from both the local effects of eliminating snow cover in mid-latitudes and a remote effect over source regions in the Arctic, where −40°C air masses are no longer able to form.     

Carbon Sequestration, Soil Conservation, and the Kyoto Protocol: Summary of Implications

This paper discusses relationships between soil conservation, carbon sequestration, and the Kyoto Protocol. The Kyoto Protocol is the first attempt to use the flexibility of the global market place to stabilize and reduce GHG emissions, mitigate climate change, and promote sustainable development. The protocol emerged first as a framework agreement, but through international negotiations it is progressing into sets of legal articles. These impose obligations on all signatories, but they also identify opportunities for improved environmental land management at local, national and international levels. This is particularly true for soil conservation, where the sequestration of carbon above and below ground increases soil organic matter, enhances soil fertility, and improves production, while concomitantly reducing atmospheric CO₂. It is a classic `win-win' situation. Both the evolving opportunities and the obligations under the Kyoto Protocol are discussed in the paper.     

Seasonal carbon dioxide balance and respiration of a high-arctic fen ecosystem in NE-Greenland

Summary  Turbulent fluxes of CO₂ were continuously measured by eddy correlation for three months in 1997 over a gramineous fen in a high-arctic environment at Zackenberg (74°28′12″N, 20°34′23″W) in NE-Greenland. The measurements started on 1 June, when there was still a 1–2 m cover of dry snow, and ended 26 August at a time that corresponds to late autumn at this high-arctic site. During the 20-day period with snow cover, fluxes of CO₂ to the atmosphere were small, typically 0.005 mg CO₂ m⁻² s⁻¹ (0.41 g CO₂ m⁻² d⁻¹), wheres during the thawed period, the fluxes displayed a clear diurnal variation. During the snow-free period, before the onset of vegetation growth, fluxes of CO₂ to the atmosphere were typically 0.1 mg CO₂ m⁻² s⁻¹ in the afternoon, and daily sums reached values up to almost 9 g CO₂ m⁻² d⁻¹. After 4 July, downward fluxes of CO₂ increased, and on sunny days in the middle of the growing season, the net ecosystem exchange rates attained typical values of about −0.23 mg m⁻² s⁻¹ at midday and max values of daily sums of −12 g CO₂ m⁻² d⁻¹. Throughout the measured period the fen ecosystem acted as a net-sink of 130 g CO₂ m⁻². Modelling the ecosystem respiration during the season corresponded well with eddy correlation and chamber measurements. On the basis of the eddy correlation data and the predicted respiration effluxes, an estimate of the annual CO₂ balance the calender year 1997 was calculated to be a net-sink of 20 g CO₂ m⁻² yr⁻¹. Received October 6, 1999 Revised May 2, 2000     

The warmest year 2015 in the instrumental record and its comparison with year 1998

本文利用CRU、NASA和NOAA的近地面气温异常(SATA)数据,对比分析了2015年和1998年的温度异常分布特征,证实了2015年是有观测记录以来温度最暖的一年,并进一步利用EEMD方法探讨了不同时间尺度对2015年温度异常的贡献以及其温度最暖的形成原因。结果表明,年代际及其以上的时间尺度和长期增暖趋势对2015年年平均SATA贡献为0.64°C,远远大于与ENSO信号相关的年际时间尺度的贡献(为0.1°C),说明长时间尺度和全球长期变暖趋势对2015年温度异常的形成有重要贡献。     

上海秋冬季地表能量平衡及CO2通量特征分析

利用2012年11月11日至2013年1月20日上海秋冬季涡动相关通量观测资料,对比分析地表能量平衡和CO₂通量在不同天气条件下的日变化特征。结果表明：2012-2013年上海晴天和多云天气条件下,最大能量通量为储热项,其次为感热项;用于蒸发的潜热通量项最小,低于50 w·m^-2。储热项日峰值出现在11时,出现时间早于净辐射通量,而在日落前转为负值。感热项日变化曲线并不以12时为中心呈对称分布,日落后感热项仍为明显正值。中午至日落时波文比值为3以上。感热通量受风向影响最大,在主导风向为西北风时,感热通量日峰值从其他风向的175 w·m^-2左右减小至120 w·m^-2左右。霾和云对短波辐射均表现为衰减作用,云的衰减作用明显大于霾。云使地表向上长波辐射和净长波辐射明显减少,而使大气逆辐射增加。晴天条件下,全天表现为CO₂排放源,且日变化呈双峰型,两个峰值出现时间正好对应上下班高峰时段,傍晚峰值大于早上峰值。     

Carbon reduction in the real world: how the UK will surpass its Kyoto obligations

Abstract

Carbon dioxide emissions from UK energy use have fallen by more than 20% over the last 30 years, and carbon intensity—carbon emissions per unit of GDP—has halved. These reductions have been achieved by a combination of decarbonisation of the energy system and substantial improvements in energy efficiency. Use of natural gas in power generation has been a big factor in recent years, but energy efficiency improvements in households and particularly industry have been more important over a longer period. Government policies designed primarily to address climate change have not been important contributors, until recently.

Future reductions in emissions will require more proactive policies. However, they are possible without any economic difficulties, notably by adopting cost-effective energy efficiency measures, using new renewable energy sources and reducing dependence on private cars. These policies will improve economic efficiency. The new UK Climate Change Programme includes policies that combine regulation, investment, fiscal measures and other economic instruments. By working with the grain of other social, environmental and economic policies, they can achieve far more than a carbon tax alone, set at any politically acceptable level. Modelling the costs of emission reductions using a carbon tax as the only instrument would not only massively over-estimate costs, it would bear little resemblance to real world politics.

The paper demonstrates that a more diverse set of policy instruments is likely to be an effective and politically acceptable approach in a mature industrial economy. It is concluded that the UK's Kyoto target of a 12.5% reduction in greenhouse gas emissions is not challenging. The UK Government's target of reducing carbon dioxide emissions by 20% between 1990 and 2010 is also achievable. By 2010 per capita emissions from the UK will be well below 2.5 tC per year. Claims that some countries, notably the USA, could not reduce per capita emissions below 6 tC per year seem inconsistent with this experience.     

Carbon reduction in the real world: how the UK will surpass its Kyoto obligations

Carbon dioxide emissions from UK energy use have fallen by more than 20% over the last 30 years, and carbon intensity — carbon emissions per unit of GDP — has halved. These reductions have been achieved by a combination of decarbonisation of the energy system and substantial improvements in energy efficiency. Use of natural gas in power generation has been a big factor in recent years, but energy efficiency improvements in households and particularly industry have been more important over a longer period. Government policies designed primarily to address climate change have not been important contributors, until recently.Future reductions in emissions will require more proactive policies. However, they are possible without any economic difficulties, notably by adopting cost-effective energy efficiency measures, using new renewable energy sources and reducing dependence on private cars. These policies will improve economic efficiency. The new UK Climate Change Programme includes policies that combine regulation, investment, fiscal measures and other economic instruments. By working with the grain of other social, environmental and economic policies, they can achieve far more than a carbon tax alone, set at any politically acceptable level. Modelling the costs of emission reductions using a carbon tax as the only instrument would not only massively over-estimate costs, it would bear little resemblance to real world politics.The paper demonstrates that a more diverse set of policy instruments is likely to be an effective and politically acceptable approach in a mature industrial economy. It is concluded that the UK’s Kyoto target of a 12.5% reduction in greenhouse gas emissions is not challenging. The UK Government’s target of reducing carbon dioxide emissions by 20% between 1990 and 2010 is also achievable. By 2010 per capita emissions from the UK will be well below 2.5 tC per year. Claims that some countries, notably the USA, could not reduce per capita emissions below 6 tC per year seem inconsistent with this experience.     

Russian behaviour in the market for permits under the Kyoto Protocol

After the US withdrawal from the Kyoto Protocol and the extension of national quotas in the Bonn and Marrakesh agreements, meagre environmental effects and a low price of emission permits are likely to be the outcome of implementation. This paper attempts to analyze this scenario, mainly in relation to the Russian case. I discuss on the basis of certain key assumptions the strategic options open to the supply side of the permit market and Russia’s potentially incompatible interests as a producer of oil and gas on the one hand and a dominating seller of emission permits under the Kyoto Protocol on the other. The analysis shows that Russian oil and gas interests are likely to boost Russia’s inclination to sell permits, ultimately resulting in lower permit prices.     

Influence of solar wind energy flux on the interannual variability of ENSO in the subsequent year

作为地球系统的主要能量来源,进入地磁系统的太阳风能量通量(E_(in))一直难以估算。因此,E_(in)对气候的影响也没有得到广泛的研究。基于三维磁流体动力模拟估算的E_(in),本文指出,太阳风能量通量不仅存在准11年周期的年代际变率,同时还存在2-4年周期的年际变率。与以往主要关注太阳活动在年代际尺度上的气候效应的研究不同,本文揭示出太阳风能量通量与次年ENSO年际变率存在显著的联系。     

Russian behaviour in the market for permits under the Kyoto Protocol

After the US withdrawal from the Kyoto Protocol and the extension of national quotas in the Bonn and Marrakesh agreements, meagre environmental effects and a low price of emission permits are likely to be the outcome of implementation. This paper attempts to analyze this scenario, mainly in relation to the Russian case. I discuss on the basis of certain key assumptions the strategic options open to the supply side of the permit market and Russia's potentially incompatible interests as a producer of oil and gas on the one hand and a dominating seller of emission permits under the Kyoto Protocol on the other. The analysis shows that Russian oil and gas interests are likely to boost Russia's inclination to sell permits, ultimately resulting in lower permit prices.     

春季青藏高原感热对中国东部夏季降水的影响和预测作用

利用1980-2012年青藏高原中、东部71个站点观测资料、全中国756站的月降水资料、哈得来中心提供的HadISST v1.1海温资料以及ERA-Interim再分析资料,综合青藏高原的感热加热以及全球海温,研究了春季青藏高原感热对中国东部夏季降水的影响,并建立预报方程,探讨了青藏高原春季感热对中国降水的预报作用。结果表明,青藏高原春季感热与中国东部降水关系密切,青藏高原春季感热异常增强伴随着长江流域中下游同期降水增多,后期夏季长江流域整流域降水也持续偏多,华南东部降水偏少。春季青藏高原感热的增强与环北半球中高纬度的罗斯贝波列密切相关,扰动在北太平洋形成的反气旋环流向西南方向延伸至西北太平洋,为长江流域输送大量的水汽,有利于降水的发生。夏季,伴随着前期青藏高原感热的增强,南亚高压位置偏东,西北太平洋副热带高压（西太副高）位置偏西偏南,西太副高北侧为气旋式环流异常。在西太副高的控制下,华南东部降水减少;西太副高西侧的偏南气流为长江流域带来大量水汽,并与来自北部气旋式环流异常西侧的偏北风发生辐合,降水增多。青藏高原春季感热异常是华南和长江流域夏季降水异常的重要前兆信号。加入青藏高原春季感热后,利用海温预报的华南、长江流域夏季降水量与观测值的相关系数有所提高,预报方程对区域降水的解释方差提高约15%。      

On the role of roughness lengths in flux parameterizations of boundary-layer models

Flux-profile relationships based on surface-layer similarity theory are used to derive relationships between the Monin-Obukhov stability parameter = z/L and the bulk Richardson number Ri _b . In contrast to previous studies, the roughness length for heat, z _0h ,is assumed unequal to the roughness length for momentum, z _0m .For the stable case, an analytic expression of in terms of Ri _b can be derived and in the unstable case, the solution is obtained through a simple iterative process.Errors introduced from the simplification of z _0h = z _0m are evaluated and are shown to be very significant in most cases. Thus, this error in many practical applications may invalidate the intended solution.     

On the role of flux adjustments in an idealized coupled climate model

 The effect of employing flux adjustments on the climatic response of an idealized coupled model to an imposed radiative forcing is investigated with two coupled models, one of which employs flux adjustments. A linear reduction (to the planetary longwave flux) of 4 W/m² is applied over a 70 y period and held constant thereafter. Similar model responses are found (during the initial 70 y period) for global-scale diagnostics of hemispheric air temperature due to the nearly linear surface-air temperature response to the radiative forcing. Significant regional scale differences do exist, however. As the perturbation away from the present climate grows, basin-scale diagnostics (such as meridional overturning rates) begin to diverge between flux adjusted and non-flux adjusted models. Once the imposed radiative forcing is held constant, differences in global mean air temperature of up to 0.5 °C are found, with large regional-scale differences in air temperature and overturning rates within the North Atlantic and Southern Ocean. Two additional experiments with the flux adjusted model (beginning from points further along the control integration) suggest that the elimination of much of the coupling shock before the radiative forcing is applied leads to results slightly closer to the non-flux adjusted case, although large differences still persist. In particular a dipole structure indicating an enhanced warming within the Pacific sector of the Southern Ocean, and cooling within the Atlantic sector is not reproduced by the flux adjusted models. This disparity is intimately linked to the Southern Ocean overturning cell along with the flux adjustments employed as well as the drift arising from coupling shock. If a similar form of sensitivity exists in more realistic coupled models, our results suggest: (1) perturbation experiments should not be undertaken until after the coupled model control experiment is carried out for several hundred years (thereby minimizing the coupling shock); (2) care should be exercised in the interpretation of regional-scale results (over the ocean) in coupled models which employ flux adjustments; (3) care should also be taken in interpreting even global-scale diagnostics in flux adjusted models for large perturbations about the present climate. Received: 15 November 1996 / Accepted: 4 June 1997     

球面E-P通量的计算及其应用

讨论了行星波作用通量Eliassen-Palm flux(E-P通量)在球面准地转条件下的表达式,纬圈环状总质量权重的变换形式,及其在绘图分析中的应用与技巧。结合实例,通过对欧洲中心再分析资料Interim的计算绘图,说明不同形式E-P通量在实际分析时的差异及特点。     

Net radiation,sensible and latent heat flux densities on slopes computed by the energy balance method

Energy balance components obtained over five grass-covered sloping surfaces near Manhattan, KS, using the Bowen ratio energy balance technique with the instruments mounted horizontally were compared with calculated values when the instruments were mounted parallel to the surfaces. Hourly values of the components changed when the instruments were parallel to the surfaces. The changes were larger at low solar angles (spring and fall) and on steeper slopes. An area average of daylight totals, assuming that all aspects were equally represented, changed only 0.1% on June 6 and 2.3% on October 11. The calculations, extended to steeper slopes, indicated small changes in the daylight totals for slopes of less than 10 deg.Supported in part by a grant from NASA NAG 5-901.     

Suburban-rural energy balance comparisons in summer for Vancouver,B.C.

Simultaneous energy balance observations at a rural and a suburban site in Vancouver, B.C. during the summer of 1983 are presented. The study is a follow-up to that conducted in 1980. Many of the 1980 results were unexpected and the present study seeks to assess their representativeness. The net radiant, turbulent sensible, and rural soil heat flux densities were measured directly. The suburban heat storage was parameterized and the turbulent latent heat flux densities were resolved as residuals in the energy balances. The 1983 average diurnal energy partitioning for both sites was typical of those quoted in the literature, suggesting that the 1980 results represent an extreme case. Suburban-rural differences showed the suburban area to have a 4% increase in net radiation, a 51% increase in turbulent sensible heat, and a 46% decrease in turbulent latent heat flux density. The values of the average daytime Bowen ratio were 0.46 and 1.28 for the rural and suburban areas, respectively. The sensible heat flux density exhibited relatively large values in the late afternoon and remained directed upward on many summer evenings. Large day-to-day variability in the relative magnitude of the suburban turbulent fluxes may have been due to synoptic influences. In this environment, the turbulent surface and mixed layers are closely coupled because of the low aerodynamic resistance over the rough surface.