气溶胶对AVHRR通道反照率的影响

通过数值模拟,考察了大气气溶胶对AVHRR通道1,2和整个太阳光谱区的行星反照率和地面反照率的影响,并研究了气溶胶对行星反照率和地面反照率之间关系的影响.     

青藏高原晴空行星反照率与地面反照率关系的研究

本文利用了大气-地球系统的物理模型推导了晴空行星反照率与地面反照率之间的相互关系,指出当仅考虑一次地面反射时,行星反照率是地面反照率的一次线性函数,当考虑到大气与地面的多次反射时,两者的关系设为二次抛物线函数,并利用1986年中美青藏高原联合考察期间的地面辐射资料以及同期NOAA-9的GAC资料对上述关系进行了试验,结果表明,两种关系都能较好地反映出青藏高原行星反照率与地面反照率之间的关系,但二次函数表现的物理意义更为明确。 青藏高原作为一个特殊的地理类型,其行星反照率与地面反照率的相互关系与全球纬向平均相比较也有明显的差异,本文讨论了这些差异的物理意义,同时分别讨论了该地区可见光和近红外这二个通道的滤过反照率与地面分光谱反照率之间的关系。 青藏高原晴空反照率与地面反照率关系的研究为利用AVHRR资料反演青藏高原地面反照率的数值分布图提供了理论依据和具体方法。     

基于CERES观测数据的全球行星反照率时空变化特征分析

为了理解行星反照率时空变化规律及成因,基于CERES数据对全球行星反照率的大气(主要为云与气溶胶等)和地表贡献进行了分解,通过Theil-Sen+Mann-Kendall方法得到了2001～2018年全球行星反照率及其大气和地表贡献的时空变化趋势,并基于回归分析方法对典型区域的变化趋势进行了初步解释.研究结果表明:1)...     

应用AVHRR的卫星辐射资料计算青藏高原地区的行星反照率与射出长波辐射

本文叙述了应用AVHRR的卫星辐射资料计算行星反照率和射出长波辐射的方法。我们用Hense的两流近似辐射模式导出了总行星反照率与AVHRR在0.58—0.68μm和0.725—1.1μm观测所得的滤过反照率的关系式。用Schmetz的两流近似辐射模式导出了总射出长波辐射通量密度与AVHRR在10.55—11.4μm观测所得的谱辐射率的关系式。根据模式计算,我们得到了下垫面的特性(地表反照率)与海拔高度对行星反照率影响的一些有意义的结果。文中应用这一方法计算与分析了青藏高原地区1982年2月15日AVHRR的观测资料。     

气候模式对海冰反照率参数化的敏感性

在NCAR的通用气候模式(CCM)中,用三种海冰反照率参数化方案,各作一年的模拟试验,与控制试验结果作比较,以检验这些参数化对极地表面温度、行星反照率和云的影响.试验I中所用的1977年春、夏季北极海盆的海冰反照率是从国防气象卫星图像(DMSP)推演得到的.试验Ⅱ将冰沟和融水池部分预先指定并采用反照率加权方案.试验Ⅲ含有相互作用的海冰/雪反照率参数化的耦合,它为表面状态的函数. 结果表明,与控制试验中所用的标准CCM海冰反照率方案相比,预先指定的或假定的“真实”卫星海冰反照率会产生更高的行星反照率.结果在北极地区温度更低(低0.5K),云量增多.标准CCM海冰反照率方案用来调节,以维持极地海洋“正常”温度.冰沟和融水池增暖海冰地区的辐射作用只是短时间的.与控制值相比,第三种方案明显地得出更低的行星反照率(减少0.07到0.17),及较高的表面温度(高2.0K). CCM摸拟出春、夏北极云量逐渐减少,而观测表明,春季云量陡增.因此有必要检验CCM的程序,特别是云的参数化.     

火山气溶胶的辐射影响

本文应用辐射传输计算研究了火山气溶胶,特别是大的火山爆发后短时期及火山周围地区内的火山气溶胶,对到达地面的向下的总的太阳辐射通量、行星反照率及大气加热率的可能影响.     

SO2与CO2反向气候效应的模拟

ＳＯ２构成的去凝结核会增加行星反照率，因此可使行星变冷。这种效应可抵消由温室气体增加造成的全球增暖。在二维模式中详细论述了矿物燃料燃烧与影响云反照率的ＳＯ２的关系以便计算气候效应。尽管我们在硫酸盐气溶胶和大气源汇方面的知识存在很大缺陷，还是有可能得出一般性结论。按保守算法，结果表明由于ＳＯ２排放导致的变冷作用目前能抵消ＣＯ２增温效应的５０％，模式预测出自１９８０年以来有一个强大的增温趋势，仅１９８     

地表反照率研究进展

地表反照率是陆面过程模式及气候模拟研究中的一个重要参数,地表反照率的变化会改变整个地气系统的能量收支平衡,并引起局地以至全球的气候变化。不同下垫面地表反照率存在明显的差异,中国区域地表反照率的空间分布也存在明显的区域差异。遥感反演地表反照率在空间上具有较高的精度,但反演结果很难直接应用于陆面过程模式。各种陆面模式对地表反照率计算主要基于陆面土地覆盖分类,包含了许多先验的预定参数,由于某些过程处理中的简化假设,从而对地表反照率的计算带来一定的误差。      

青藏高原地表反照率计算研究

根据改进的甚高分辨率扫描辐射仪（ＡＶＨＲＲ）５个观测波段的光谱特征，经多次试验，设计了一组从卫星观测的地－气系统的辐射测值中提取晴空资料的多通道门槛值判识法和提取月平均反照率的合成法；并对１９９２年ＮＯＡＡ－１２卫星获取的ＡＶＨＲＲ资料进行计算处理，分析提取晴空数据，在此基础上按卫星轨道覆盖周期合成计算得到的晴空行星反照率和地表反照率，并且计算了逐月的地表反照率。对计算结果做了初步分析和认真比较。     

利用MODIS资料反演兰州地区气溶胶光学厚度

借助6S模式对MODIS的蓝光(0.46μm)、红光(0.66μm)和中红外(2.1μm)通道进行了行星反照率对地表反射率和气溶胶光学厚度的敏感性试验, 并对蓝光和红光通道的路径辐射对行星反照率的贡献做了数值试验; 计算了MODIS的蓝光、红光和中红外通道在兰州市及其周围地区的地表反射率, 检验了Kaufman给出的三个通道地表反射率之间的关系。检验结果表明, 在兰州周围地区蓝光通道与中红外通道地表反射率之间的关系与Kaufman给出的关系比较符合, 对于兰州周围大范围区域都是适用的。利用此关系通过6S模式进一步反演了兰州城市及其附近地区 1×104 km2 范围内的气溶胶光学厚度, 反演结果较为合理。     

La conversion du rayonnement sphérique en rayonnement global

Résumé Une étude théorique permet d'estimer les sommes journalières soit du rayonnement global tombant sur un récepteur plan et horizontal, soit du rayonnement sphérique ou circumglobal tombant sur une sphère. Ces deux sommes dépendent fortement des conditions atmosphèriques: atmosphère pure, brume, humidité et nébulosité, ainsi que de la latitude géographique, de la déclinaison du soleil et de l'albédo du sol. On montre qu'il est quand-même possible de trouver une relation du deuxième ou troisième degré entre les deux types de mesures où les coefficients ne dépendent que de la différence – entre latitude et déclinaison et de l'albédo du sol. Cette relation est valable dans les basses latitudes <30° avec une faible dispersion des valeurs journalières; dans les latitudes plus élevées sa validité semble limitée au semestre estival.

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Summary The daily totals of radiation falling on a horizontal receiver as well as on a spherical one are calculated by theoretical approach. Both types of values change very much with atmospherical conditions, such as pure atmosphere, haze and humidity of the atmosphere and cloudiness and furthermore with the geographical latitude, the declination of sun and finally with the albedo of the ground. It is demonstrated that it is nevertheless possible to establish a relation of second or third order between both these types of values. The coefficients are function only of –, the difference between latitude and declination and of the albedo . This relation is valid in low latitudes <30° for daily totals; in higher latitudes its validity is limited to days of the summer period.

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Zusammenfassung Auf theoretischem Wege werden die Tagessummen sowohl der auf einen horizontalen Empfänger fallenden Globalstrahlung von Sonne und Himmel als auch der auf eine Kugel fallenden Zirkumglobalstrahlung ermittelt. Beide Werte hängen sehr stark von den atmosphärischen Verhältnissen, wie Reinheit der Atmosphäre, Dunst, Feuchtigkeit und Bewölkung, sowie von der geographischen Breite, der Deklination der Sonne und der Albedo der Bodenoberfläche ab. Es wird nun gezeigt, daß es trotzdem möglich ist, eine Beziehung zweiten oder dritten Grades zwischen den beiden Arten von Tagessummen herzuleiten, in der die Koeffizienten nur von der Differenz – zwischen geographischer Breite und Deklination der Sonne einerseits und der Albedo andererseits abhängen. Diese Beziehung gilt in niederen Breiten <30° für alle Einzelwerte, in höheren Breiten nur im Sommerhalbjahr.

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Avec 8 Figures     

Radiation balance in a tropical city — Delhi (India)

The impact of urbanization is assessed by comparing values of the radiation parameters at an urban location with those of a rural site. Urban Delhi was divided according to land-use and the effects of urbanization was studied on incoming short-wave (K), albedo, incoming longwave (L, outgoing longwave (L), and net radiation (Q ^*), were individually studied at four representative sites (Rural, Commercial, Residential and Industrial). MaximumK was observed in the rural and commercial areas whereas highL was observed in the commercial and industrial locations. High depletion ofK of the order of 13% was observed for the industrial location in the winter season. An increase ofL in, the industrial location is of the same order as that of the commercial location, i.e. 20%. The residential location shows quite moderate (4.6%) depletion ofK in comparison with other sites.Nomenclature U Urban - R Rural - K Incoming Short-wave radiation - L Incoming Long-wave radiation - L Outgoing Long-wave radiation - Q ^* Net Radiation - Albedo - K ^* Net Short-wave radiation - L ^* Net Long-wave radiation     

The role of money and the financial sector in energy-economy models used for assessing climate and energy policy

This article outlines a critical gap in the assessment methodology used to estimate the macroeconomic costs and benefits of climate and energy policy, which could lead to misleading information being used for policy-making. We show that the Computable General Equilibrium (CGE) models that are typically used for assessing climate policy use assumptions about the financial system that sit at odds with the observed reality. These assumptions lead to ‘crowding out’ of capital and, because of the way the models are constructed, negative economic impacts (in terms of gross domestic product (GDP) and welfare) from climate policy in virtually all cases.

In contrast, macro-econometric models, which follow non-equilibrium economic theory and adopt a more empirical approach, apply a treatment of the financial system that is more consistent with reality. Although these models also have major limitations, they show that green investment need not crowd out investment in other parts of the economy – and may therefore offer an economic stimulus. Our conclusion is that improvements in both modelling approaches should be sought with some urgency – both to provide a better assessment of potential climate and energy policy and to improve understanding of the dynamics of the global financial system more generally.

POLICY RELEVANCE

This article discusses the treatment of the financial system in the macroeconomic models that are used in assessments of climate and energy policy. It shows major limitations in approach that could result in misleading information being provided to policy-makers.     

Atmospheric trace gas measurements at Palmer Station,Antarctica: 1982–83

In early 1982 a station capable of sampling atmospheric trace gas constituents on a continuous basis was established at Palmer Station, Anvers Island, adjacent to the Antarctic Peninsula (64° 46S 64° 04W). Sampling operations began about 1 February 1982. This is an initial report on this station, its location, equipment and general research objectives along with some initial sampling results. The constituents being measured and recorded were: ozone, methane, carbon dioxide, carbon monoxide, CCl₃F (fluorocarbon-11), CCl₂F₂ (fluorocarbon-12), carbontetrachloride, methylchloroform, nitrous oxide, and Aitken nuclei (CN). Data storage, data processing, and sampling system control is handled by a Hewlett-Packard 85 system. Preliminary analyses of about the first 20–22 months of data are presented and show not only the expected long-term trends but also shorter period concentration cycles that seem to be related to synoptic meteorology.     

Australian public perception of the greenhouse issue

During 1987 and 1988 in Australia there have been two national meetings on the greenhouse effect and a campaign designed to increase public awareness. A study of the backgrounds, level of comprehension and attitudes of attendees at two state Greenhouse-88 meetings has been undertaken by means of a questionnaire survey and a set of personal interviews. Two crucial caveats pertain: (1) some of the questions reflect the prejudices of the author who is an atmospheric scientist and much of the interpretation is similarly tainted and (2) the respondents comprise a small, self-selected and probably highly motivated group. All the ensuing results should be viewed in the context of these caveats.Over 97% of the respondents believe that action should be taken now to alleviate or mitigate the effects of increased greenhouse gases. Despite the fact that the majority of the 321 respondents are professional people (73%) and that over 53% have tertiary level educational qualifications, there was a failure to grasp some fundamental issues. For example, only 120 (37%) correctly recognized that N₂ is not a greenhouse agent whilst also agreeing that CO₂, CH₄ and CFCs are greenhouse agents. On the other hand, the respondents generally demanded a relatively low level of confidence (50% to 70% certainty) about the greenhouse issue from scientists before action is taken. Sixty-four percent believe that life will be worse for them and/or their children in Australia in Greenhouse 2025 with the youngest age range being the second most pessimistic group about the future.Relatively little interest was shown in the possibility of obtaining more information on topics that interest climatic scientists such as the validity of measured temperature trends and inadequacies/errors in climate models but more information was desired on the social and economic implication and, interestingly, on the scientific background to the issues. Overall, teachers are perceived as trying to increase understanding; whereas politicians, multinational corporations, the media and some extreme environmentalists are perceived as often attempting to deceive intentionally. Scientists are seen as neither especially malevolent nor benign. A possible conclusion which might be drawn is that by attempting to simplify issues for public debate, scientists may significantly reduce, or even remove entirely, any chance of re-association of connected issues by members of the public. Perhaps more importantly, scientists need to recognize and learn to use the knowledge that the public may have the right views for the wrong reasons.     

Nine Fallacies of Floods

A number of important misconceptions or fallacies stand in the way of a better understanding of the nation's flood problem. The fallacies are not universal, with many flood experts, decision makers, and sectors of the public escaping their seductive logic. But enough people do fall prey to these fallacies of floods so as to create obstacles to improved utilization of the lessons of experience. This paper uses three of these lessons to organize presentation of the nine fallacies:We know the wrong things about the nature of the problem.Fallacy 1: Flood frequencies are well understood.Fallacy 2: Damaging flooding in recent years is unprecedented because of global warming.Fallacy 3: Levees prevent damages.Fallacy 4: Flood forecasts are universally available.We don't know enough about why and with what intensity we should act.Fallacy 5: Societal vulnerability to floods is well understood.Fallacy 6: Data on flood casualties is a proxy for flood risk.Fallacy 7: Data on flood damages is a proxy for flood risk.We know enough about what might be done. Fallacy 8: Knowledge leads to action.Fallacy 9: The U.S. flood problem can be addressed without Federal leadership and support.The purpose of raising the fallacies in this paper is to contribute to a systematic definition of the nation's flood problem.     

Telling stories with models and making policy with stories: an exploration

Narrative research is in vogue in the social sciences. A current debate in philosophy of economics concerns the role of storytelling in economic modelling, and a growing research programme in policy studies investigates the influence of stories on policy outcomes. These two streams of research have yet to be connected in an investigation of how scientific models, in addition to delivering numerical results, also shape policy through the stories that are told with them. This article addresses that gap, arguing that stories produced with integrated assessment models of global climate change are particular types of policy narratives. An analytical framework for studying their composition and content is suggested. The narrative analysis of modelled stories illuminates some of the models' underpinning values and beliefs. These values and beliefs influence the normative, policy-relevant conclusions generated with the models. For illustration, the framework is applied to the analysis of two variations of the Dynamic Integrated Climate Economy model that are used to tell different stories about climate justice and climate policy.

Key policy insights

• IAMs consist of mathematical structures and the stories told by manipulating these structures.

• There is an intricate but not fully deterministic relationship between IAM structures and stories.

• Examining both these elements contributes to our understanding of the models' role in climate governance.

• Appreciation of modelled stories may facilitate more effective use of IAMs in the policy process.

     

On a bora event simulated by the Eta Model

Summary ¶This study presents a numerical simulation of the bora wind as it occurs in form of a severe wind blowing down coastal mountains and over the Adriatic Sea. A typical cyclonic bora event, occurring during the period January 3–6, 1995, is simulated using a nested limited area model. An integration, with horizontal resolution of about 14km, and a nested one, with higher resolution, about 5.5km, are presented. The 1997 version of the Eta Model is used for both the lower resolution and the higher resolution runs. Numerous details of the simulation are found to be in good agreement with the understanding as well as the observational knowledge of the bora, thus supporting confidence in the realism of the results. In particular, features of the simulated flow are seen strongly indicative of some basic characteristics of the hydraulic model of the phenomenon, such as the mountain wave breaking and the upstream flow acceleration. Moreover, the increase in horizontal resolution, in combination with an improvement of the coastal SST information, led to a still improved realism of the low-level wind representation over the Adriatic Sea.Received December 31, 2001; revised March 25, 2002; accepted July 19, 2002 Published online: February 20, 2003     

Temperature-sensitive Tien Shan tree ring chronologies show multi-centennial growth trends

Two millennia-length juniper ring width chronologies, processed to preserve multi-centennial growth trends, are presented for the Alai Range of the western Tien Shan in Kirghizia. The chronologies average the information from seven near-timberline sampling sites, and likely reflect summer temperature variation. For comparison, chronologies are also built using standard dendrochronological techniques. We briefly discuss some qualities of these inter-decadal records, and show the low frequency components removed by the standardization process include a long-term negative trend in the first half of the last millennium and a long-term positive trend since about AD 1800. The multi-centennial scale Alai Range chronologies, where these trends are retained, are both systematically biased (but in an opposite sense) in their low frequency domains. Nevertheless, they represent the best constraints and estimates of long-term summer temperature variation, and reflect the Medieval Warm Period, the Little Ice Age, and a period of warming since about the middle of the nineteenth century.     

Boundary layer aspects and elevated heat source effects of the Alps

Summary High pressure influence in the whole inner-ALPEX area on April 22, 1982 gave an opportunity for the ALPEX scientific task no. 6: To study the effects of differential radiative heating introduced by the alpine mountain range due to elevation, topographic features and albedo. Electra flight E-422 with its four-fold north-south, south-north flight tracks was especially devoted to study the diurnal variations of the atmospheric boundary layer and the airflow on both sides of the Alps along the Gotthard cross-section under strong inversion conditions. Using the flight technique of vertical zigzagging, a total of 24 vertical soundings have been completed along four traverses.Synoptic rawinsonde and surface data, digital satellite data and microbarograph data are used to examine the thermodynamical aspects of the diurnal development of the alpine heat low. The fine structure of the boundary layer is documented by cross-sectional analysis of the potential temperature, mixing ratio and the three wind components from the 1 Hz aircraft data along the traverses. In addition, 15 aircraft soundings have been selected to evaluate the vertical distribution of the turbulent variances and fluxes on both sides of the Alps. The differences of the structure and temporal evolution of the alpine boundary layer on the north and south side of the Alps, as well as the differences between the alpine boundary layer and the boundary layer over homogeneous terrain are significant and need further discussion.

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Aspekte der Grenzschicht und Effekte der erhöhten Wärmequelle der Alpen

Zusammenfassung Hochdruckeinfluß im gesamten inneren ALPEX-Gebiet am 22. April 1982 ermöglichte die ALPEX-Aufgabe Nr. 6: die Effekte unterschiedlicher Strahlungserwärmung, welche je nach Höhenlage, topographischen Gegebenheiten und Albedo der alpinen Gebirgskette verursacht werden, zu untersuchen. Der Electra-Flug E-422 mit seinen vierfachen Nord-Süd, Süd-Nord-Flugrouten beschäftigte sich besonders mit der Untersuchung der täglichen Veränderung der atmosphärischen Grenzschicht und der Luftströmung an beiden Seiten der Alpen entlang des Querschnittes beim Gotthard bei ausgeprägten Inversionen. Unter Verwendung der Flugtechnik des vertikalen Zickzacks wurden insgesamt 24 Vertikalsondierungen entlang von vier Schnittlinien durchgeführt.Synoptische Radiosonden- und Bodendaten sowie digitale Satelliten- und Mikrobarographendaten werden zur Untersuchung der thermodynamischen Aspekte der täglichen Entwicklung des alpinen Hitzetiefs verwendet. Die Feinstruktur der Grenzschicht wird durch Querschnittanalysen der potentiellen. Temperatur, des Mischungsverhältnisses und der drei Windkomponenten aus den vom Flugzeug entlang der Schnittlinien gewonnenen 1 Hz Daten dokumentiert. Darüber hinaus wurden 15 Flugzeugsondierungen ausgewählt, um die vertikale Verteilung der turbulenten Varianzen und Flüsse an beiden Seiten der Alpen zu beurteilen. Sowohl die Unterschiede in der Struktur und der zeitlichen Entwicklung der alpinen Grenzschicht an der nördlichen und der südlichen Seite der Alpen als auch die Unterschiede zwischen der alpinen Grenzschicht und der Grenzschicht über homogenem Gelände sind signifikant und erfordern eine weitere Diskussion.

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With 8 Figures