湿斜压大气中暴雨中尺度系统发展的一种可能机制

根据暴雨中尺度系统发生时的大气运动特征,在绝热、无摩擦条件下,从湿斜压原始方程出发,考虑大气运动的涡度及散度演化不仅受动力场的制约,而且还受到热力场的约束,采用不同于传统研究涡度及散度方程的分析方法,导出了新形式的涡度及散度方程。在此基础上,分析了湿斜压大气中对流层中低层气流旋转与辐合持续增长的动力特征,初步揭示了湿斜压大气中暴雨中尺度系统发展的动力机制。     

高低频系统相互作用对Rossby波破碎过程的影响

利用美国国家环境预报中心和能源部（NCEP/DOE）的逐日再分析资料（NCEP-DOE AMIP-Ⅱ）,对2010年12月20日发生在北太平洋一次典型的反气旋式波破碎（AWB）事件进行研究,分析了波破碎过程中等熵位涡场的演变特征,揭示了波破碎过程中高频扰动以及低频信号的逐日演变特征,并对2010年冬季350 K等熵面上逐日高频位涡（PV）扰动和低频变化做经验正交函数（EOF）分析,得到了其主要模态,并从等熵位涡方程出发研究了波破碎过程中位涡高、低频变化的原因。研究表明,波破碎过程中高频低PV空气从北太平洋西部日本附近沿东北方向向对流层上层侵入,而来自阿拉斯加湾附近的高频高PV空气向对流层下层侵入。高频位涡场EOF分解得到的前两个模态共同描述了北太平洋中纬度地区自西向东移动的天气尺度波列;低频位涡场EOF分解的第一模态在北太平洋呈弧形波列结构。天气尺度波在传播过程中受到低频场的平流作用逐渐偏离其传播主要模态的位置,并发生破碎,同时高频流场对高频位涡的平流可以产生低频变化,使得低频变化的空间形态向其冬季主要模态转变。     

1998年夏季长江中下游地区大气多尺度振荡的区域气候模拟

利用区域气候模式RegCM3对1998年夏季东亚区域气候进行了季节尺度模拟,并通过小波分解方法对长江中下游地区观测和模拟的气象要素进行多尺度分析,旨在研究区域气候模式对长江中下游地区夏季大气多尺度振荡的模拟能力。结果表明：模式对降水低频振荡的模拟要优于对其它振荡周期的模拟,而对降水高频振荡和天气尺度周期振荡的描述能力相对较弱。模式对整个对流层温度模拟偏低,且主要表现在对低频温度模拟偏低。对流层下层温度模拟误差主要是由对高频温度振荡的模拟误差造成的,对流层上层温度模拟误差主要是低频温度振荡的模拟误差造成的。由于高频温度所占方差贡献很小,因此,提高模式对整层大气低频温度变化的模拟能力显得更为重要,但总体上各种时间尺度温度振荡和梅雨期降水振荡之间并不存在对应关系。除涡度的8天周期振荡外,涡度的其它周期振荡和降水振荡之间具有较好的对应关系,梅雨降水集中期主要与16天以上涡度低频振荡和4天以下涡度高频振荡相对应,涡度天气尺度周期振荡对梅雨期降水的贡献不大。涡度振荡分量周期越长,其模拟与观测之间相关系数的垂直变化就越大,且不论周期长短,涡度各周期分量方差贡献的大小都基本相同。     

500毫巴图上相对涡度零线与地面锋面和降水的关系

涡度是流体力学中一个主要的概念。它在说明大气运动的性质方面,曾被发现了很多有用的事实。通常,在研究大范围大气运动的涡度时,我们所关心的是绝对涡度。倘若我们在绝对涡度中把局地科氏参数略去,这样可以得到相对涡度场。这对在处理对流层中部接近无辐散层的流场时,可以发现不少使我们感兴趣的,而且在实用和理论上都有价值的特征。就作者多年实践的结论是:对流层中部移动性气旋前进方向的半圆内,500毫巴图上相对涡度零线可作为最大上升运动和降水区域的指标(自然降水的发生尚有赖于空气中可提供的有用水汽量)。对     

逐日大气加热场的计算方法和个例分析

本文根据涡度方程和热力学方程, 提出了利用四层标准等压面资料倒算逐日整层垂直平均大气加热场的方法。并对冬,春两次强天气过程进行了实例计算,讨论了逐日大气加热场的大小。着重分析了加热场分布与中期环流形势演变的相互关系。     

冬季一次引发华北暴雪的低涡涡度分析

利用NCEP FNL 1°×1°再分析资料和WRF模式,模拟了2010年1月2～3日我国华北地区的一次由涡旋造成的冬季降雪过程,并采用位涡和涡度方程对引发暴雪的涡旋发展机制进行了诊断分析。结果表明,这次降雪过程中,对流层中层高空浅槽东移、加深及发展,并引导低空和地面系统自西向东移动,高空位涡的下传强迫加强了对流层中低层涡旋的发展。平均通量和涡旋区域的辐合、辐散作用对涡旋涡度的增长贡献最大,扰动通量和类倾斜项的作用较小。在中层涡旋成熟期,环境场的风速小于中层涡旋的移动速度时,环境场相对于涡旋区域为辐散,涡旋涡度减小;当环境场风速大于涡旋的移动速度时,环境场相对于涡旋区域为辐合,涡旋涡度增加。在涡旋衰减期,向涡旋外输送的绝对涡度通量使得涡旋涡度逐渐减弱。这次过程中,高空位涡强迫、低空辐合和涡旋边界平均气流对扰动涡度的输送是涡旋发展的主要机制。     

北半球冬季副热带高压带维持的涡度机制

本文利用涡度平衡方程讨论北半球冬季副热带高压的维持,计算发现,30°N副热带高压带地区,大型扰动所造成的涡度输送的辐散是维持这地区反气旋涡度的主要因子,这种辐散作用所造成的反气旋涡度主要发生在对流层上层,平均经圈环流对地转祸度的输送可以把它引导到对流层下层来。此外,我们还根据涡度输送的计算,讨论了西风急流的维持。向北的扰动涡度输送在45°N上空达极大值,因此它对中纬度西风和纬向平均急流的维持起着重要作用。但30°N上空,扰动的涡度输送为零,而平均经圈环流对地转涡度和相对涡度的输送都比较大,因此,可以认为副热带急流是在平均经圈环流作用下维持的。     

湿位涡、热力学参数CD与涡度、散度演化

从湿斜压原始方程出发,将热力学方程引入散度方程,导出了显示包含热力学参数CD影响的散度方程。在此基础上,结合湿位涡方程,分析了湿斜压大气中湿位涡水平分量MPV2及其热力学参数CD的动力学性质,揭示了由热力学参数CD表征的斜压动力过程激发对流层中低层涡、散场演变的动力机制,阐明了应用热力学参数CD诊断暴雨中尺度系统发生发展和预报暴雨的理论依据。     

一次江淮气旋发生发展动力因素的计算分析

本文对一次江淮气旋的发生发展过程计算了500mb等压面上的涡度平流,对流层下部的温度平流、大气层结稳定度、大气加热率等各项动力因素对其发生发展所起的作用。计算结果发现,在江淮气旋的发生期,大气加热率所起的作用占主要地位;在江淮气旋强烈发展时期,500mb上的涡度平流、对流层下部的温度平流、大气加热率都有重要作用,但以对流层下部的温度平流作用最大。 大气的加热场采用从温度场与流场倒算的方法。计算所得的加热场与降水场有较好的对应,故可认为该大气的加热作用主要是由水汽凝结潜热的释放所致。 计算分析得到如下结论:江淮气旋的发生时期,水气凝结潜热的释放对气旋的发生起着主要的动力作用;而在江淮气旋进一步猛烈发展时期,温度平流对气旋发展的贡献最大,也即大气本身的斜压性是它进一步发展的重要因素。     

江淮流域梅雨期持续性强降水及其10～30d低频环流特征

利用1961—2010年中国556站的逐日降水资料和NCEP/NCAR逐日再分析资料,采用合成分析等方法探讨了江淮流域梅雨期持续性强降水的低频振荡特征及其发生前后低频大气环流场的演变特征。结果表明,江淮梅雨持续性强降水存在显著的10~30 d低频振荡特征。持续性强降水发生时,江淮流域对流层高层受东海低频反气旋西北部的偏西气流控制,使得南亚高压位置偏东,加强了高层的辐散型流场;对流层中层,中高纬度地区存在"+、-、+"的低频位势高度中心,蒙古低频低压使得极地冷空气易于南侵;对流层低层,江淮流域受低频P-J波列西段的台湾岛低频反气旋影响,并伴随强烈的对流活动,此反气旋使得西太平洋副热带高压向更西的位置伸展;因此低层辐合、高层辐散使得江淮流域表现为强烈的低频上升运动,同时低频水汽从孟加拉湾-南海一带输送到江淮流域,为持续性强降水的发生提供了有利的低频环流条件。另外,在持续性强降水发生前后,低层低频正涡度向北、向西传播,高层低频负涡度向南、向东传播,高低层斜压结构明显,共同作用于江淮流域,维持持续性强降水过程。     

海面与海岸陆面风速廓线特征

利用位于江苏海岸陆地的两座测风塔以及福建海面的一座测风塔气象要素资料,分析了这两种下垫面风速、湍流等要素的日变化规律及廓线特征,探讨了这两种不同下垫面特征导致的风力特征差异。结果表明:海岸陆面日最大风速出现时间较内陆滞后,最小风速出现时间与内陆相差不大,风速日变化位相随高度滞后,日振幅随高度减小,冬季70 m高度风速日变化特征与10 m高度风速日变化特征相反,夜间大于白天,说明冬季的过渡层转换高度低于夏季;海面风速的日变化位相、日振幅等特征随高度变化很小。两种下垫面的风廓线用对数律、指数律拟合的效果相当,海岸陆面的风廓线指数呈现的规律为离岸风组大于向岸风组,冬季大于夏季;海面风廓线指数呈现的规律则是向岸风组大于离岸风组,夏季大于冬季。     

乌鲁木齐市降水对大气污染的影响

根据2002—2003年乌鲁木齐市SO2、NO2、PM10的日平均浓度和日降水量分析了乌鲁木齐市降水对3种大气污染物的湿清除能力。分析表明大雨对SO2和PM10的湿清除能力大于小雨,而小雨大于中雨。中雪对SO2和PM10的湿清除能力大于大雪,而大雪大于小雪。小量以上降水(降雨和降雪)对NO2的湿清除能力基本相当。微雨对3种大气污染物具有湿清除能力,而微雪使3种大气污染物的浓度增加。     

Policy innovation in a changing climate: Sources,patterns and effects

States have been widely criticized for failing to advance the international climate regime. Many observers now believe that a “new” climate governance is emerging through transnational and/or local forms of action that will eventually plug the resulting governance gaps. Yet states, which remain oddly absent from most discussions of the “new” governance, will remain key players as governance becomes more polycentric. This paper introduces a special issue that explores the ability of states to rise to these interconnected challenges through the analytical prism of policy innovation. It reveals that policy innovation is much more multi-dimensional than is often thought; it encompasses three vital activities: invention (centering on the ‘source’ of new policy elements), diffusion (that produces different ‘patterns’ of policy adoption), and the evaluation of the ‘effects’ that such innovations create in reality. The papers, which range from qualitative case studies to large ‘n’ quantitative studies, offer new insights into the varied roles that states play in relation to all three.They show, for instance that: the policy activity of states has risen dramatically in the past decade; that state innovation is affected to similar degrees by internal and external factors; and that policies that offer flexibility to target groups on how to meet policy goals are most effective but that voluntary reporting requirements are ineffective. This paper draws upon these and many other insights to offer a much more nuanced reflection on the future of climate governance; one that deservedly puts states at the front and center of analysis.     

上海市郊林带的气候效应

对上海市郊林带附近与非林带冬、夏季典型天气下温、湿度、蒸发、辐射量的同步观测资料分析研究显示:林带附近气温日较差比非林带大,林带背风侧气温日较差比林带迎风侧大。林带附近日蒸发量比非林带小,日平均相对湿度比非林带大。林带附近散射辐射比非林带小,反射辐射比非林带大,总辐射差异与季节及林带树叶的茂密程度有关,白天净辐射差异主要取决于总辐射和反射辐射差异,夜间净辐射差异与林带及两地地温差有关。     

Fragmentation of rangelands: Implications for humans, animals, and landscapes

Fragmentation of the ecosystems of the earth into spatially isolated units has emerged as a primary component of global change. Often, fragmentation results from actions that are intended to enhance human livelihoods and well-being; however, there are often costs to ecosystems and human economies that are not considered. We describe the three general categories of processes causing fragmentation of rangelands worldwide: dissection, decoupling, and compression. We show that access to heterogeneity of landscapes is an important attribute of grazing ecosystems worldwide, and that fragmentation of these systems, even when it proceeds in the absence of habitat loss, can limit options of people and animals, options that are particularly important in temporally heterogeneous environments. We discuss the consequences of fragmentation for people, livestock, wildlife, and landscapes and describe potential adaptations that can mitigate its harmful outcomes. We close by reviewing policy options that promote re-aggregation of landscapes and adaptation to fragmentation.     

Thermodynamics and environmental constraints make the biosphere predictable – a response to Volk

In his critique of Kleidon (Clim Change 66:271–319, 2004), Volk (Clim Change 85:3–4, 2007) concludes that maximum entropy production (MEP) has no great relevance for biological evolution and the time history of life on Earth. I think that most of his points are not justified but rather reflect (a) a lack of appreciation of the central importance of entropy production as the “universal currency” that measures what keeps systems working, including the biosphere, (b) a misunderstanding of how biotic activity is embedded in the global entropy budget, and (c) a lack of distinction between optimal environmental conditions that maximize productivity and result from environmental tradeoffs versus optimal function of organisms to some internal tradeoffs. The examples that he uses to support his conclusions show flaws in that these mostly discuss single environmental effects and immediate system responses. Optimal environmental conditions, however, requires at least two effects that result in a trade-off, so it is not surprising that his examples seem to contradict optimality and MEP. And the immediate response of a system to change can be very different than the response in steady state, for which MEP applies. This is specifically important to be considered in the context of the “cheater” problem. In summary, I do not think that Volk makes convincing arguments that contradict MEP, although I certainly agree that there is a lot more work to be done to fully recognize the great importance that thermodynamics and MEP play in shaping the Earth’s biosphere and its evolutionary history.     

The ideas of secondary school children concerning ozone layer damage

The understanding of pupils between the ages of 11 and 16 about the ozone layer — what it is, what will damage it and what will be the likely result of such damage — has been studied. Following the use of a preliminary open-form questionnaire, the ideas of a large cohort of children have been probed by closed-form questionnaire and by interviews with a subset of this group. The authors explain that most pupils seem aware that the ozone layer is a layer of gas around Earth, but less sure what that gas is. They also know that it protects Earth from ultra-violet rays from the sun, and that further depletion will allow more ultra-violet to Earth and cause more skin cancer. Most also know that one cause of depletion is the use of CFCs, but many confuse the depletion of the ozone layer with the greenhouse effect and other forms of atmospheric pollution. The authors provide evidence to suggest that such confusion of ideas is strongly held and that, even with this relatively new and abstract phenomenon, ideas are held in a consistent and similar framework by most pupils.     

The Gaia Hypothesis: Fact, Theory, and Wishful Thinking

Organisms can greatly affect their environments, and the feedback coupling between organisms and their environments can shape the evolution of both. Beyond these generally accepted facts, the Gaia hypothesis advances three central propositions: (1) that biologically mediated feedbacks contribute to environmental homeostasis, (2) that they make the environment more suitable for life, and (3) that such feedbacks should arise by Darwinian natural selection. These three propositions do not fare well under close scrutiny. (1) Biologically mediated feedbacks are not intrinsically homeostatic. Many of the biological mechanisms that affect global climate are destabilizing, and it is likely that the net effect of biological feedbacks will be to amplify, not dampen, global warming. (2) Nor do biologically mediated feedbacks necessarily enhance the environment, although it will often appear as if this were the case, simply because natural selection will favor organisms that do well in their environments – which means doing wellunder the conditions that they and their co-occurring species have created. (3) Finally, Gaian feedbacks can evolve by natural selection, but so can anti-Gaian feedbacks. Daisyworld models evolve Gaian feedback because they assume that any trait that improves the environment will also give a reproductive advantage to its carriers (over other organisms that share the same environment). In the real world, by contrast, natural selection favors any trait that gives its carriers a reproductive advantage over its non-carriers, whether it improves or degrades the environment (and thereby benefits or hinders its carriers and non-carriers alike). Thus Gaian and anti-Gaian feedbacks are both likely to evolve.     

气象因子与下垫面性质对锡林郭勒盟沙尘暴影响探析

锡林郭勒盟沙尘暴分布与气象因子和下垫面性质有关,沙尘暴西多东少的分布特征,与大风西多东少、降水西北少东南多、温度西南高东北低的分布特征基本相似;大风是沙尘暴的主要动力因子,温度是产生沙尘暴的热力因素,降水和下垫面性质决定了沙尘暴产生的环境条件。沙尘暴日数随着大风日数与温度增加(升高)而增多;随降水增加而减少;下垫面要素中的地形、地貌为沙尘暴的发生提供沙源、起沙条件;土壤成分自西北向东南为棕钙土带、栗钙土带、黑钙土带、灰色森林土带,植被覆盖度依次增加,沙尘暴分布也依次减少。     

升钟水库降水分布特征及其影响因素

作者从流域地形，气候变化以及水库影响３个方面来探讨四川省升钟水库运行初期水量不足的原因，分析结果表明，建库前后库区及库周地区年降水量时空分布趋势一致，所不同的是建库后较之建库前各地年降水量普遍偏少２００ｍｍ左右，在库周各地建库前后地形不变，且水库蓄水后对为中周站年降水量最大影响为减少近４０ｍｍ，且建库后３年连年姓严重干旱说明气候对降水的影响比水库的影响要大得多，气候变化是影响水库运动初期水量不足的