气候标准序列变率

首先,综论已有气候序列变率的各种量数,提出气候标准序列变率和推导其与他种序列变率间的关系,以资比较。然后,推导了气候标准序列变率抽样分布的参数(平均数与方差),并证明了在正态假设下这些参数的简化结果和气候标准序列变率抽样分布函数中的参数是一致的。这些是本文的重点。最后,应用气候标准序列变率的一些统计理论说明其在资料统计方面的实用价值,指出其优越性。气候标准序列变率不仅可以分析气候特征,它可以用于研究气候变迁与旱涝规律,以及用于气候统计予报。     

全球平均温度序列的比较

着重评述了目前国际上常用的3个全球平均温度序列：HadCRUT3、NCDC及GISS。后两个序列1982年之后引入了卫星观测资料。NCDC对资料作了插补,建立了1880-2009年覆盖面完整的序列。HadCRUT3序列所显示的近10年变暖的停滞可能主要是缺少极区资料造成的。NCDC与GISS两个序列依然保持约0.1℃/10a的增温。3个序列1910-2009年的变暖趋势十分接近,在0.70～0.75℃/100a之间。     

气候谱中信号和噪声的识别

1.引言以前的谱分析文章(Gray,1982)中曾提出用多重内插(MI)法鉴别高分辨率谱中峰出现的频率,X~2检验表明,这样鉴别出来的许多峰在统计上是不显著的,一般就视为“噪声”。Gray(1976)提出,在两个或两个以上与物理过程联系着的相互独立变量的时间序列谱中,如果峰出现在类似的频率上,那     

全球大气位势高度场气候变率的球函数分析

为了研究全球大气位势高度场的气候变率, 利用NCEP/NCAR再分析资料, 按照距平高度场平均强度指数 (Ia) 分析发现, 半球距平高度场强度呈年单周振荡, 冬大夏小, 冬季随高度单调增大, 夏季有弱高、低值中心出现, 而北、南半球的差异明显表现在季节变化上; 进一步根据半球大气位势高度距平场球函数谱低维、低阶的基本特征, 将半球环流异常分为半球均匀异常 ( H ′00)、纬向均匀异常 ( H ′0)、超长波尺度异常 ( H ′ul) 和长波尺度异常 ( H ′l) 4种类型, 用波数域0≤m, k≤6上的球函数系数资料求得它们的方差贡献, 给出了4类异常的方差贡献随高度、季节变化的规律以及它们的半球际差异。由此得到异常环流球函数谱结构的总体特征为:对流、平流层之间存在明显变化。从对流层进入平流层, 一般由超长波异常为主转为纬向均匀异常为主 (冬半球) 或半球均匀为主 (夏半球); 半球均匀异常在对流层中不重要, 长波尺度异常在平流层中不重要, 它们拟合异常方差一般均小于10%; 北、南半球最大差异表现在冬季平流层R′00和冬、夏季对流层R′0南半球大于北半球, 冬、夏季对流层R′l北半球大于南半球。     

气候时间序列变点的推断

本文研究时间序列的变点问题。所给出的统计方法可用来推断一个时间序列是否存在变点，存在几个变点以及变点在什么位置。这种统计推断方法可用于气候阶段的划分。     

从一维气候时间序列直接提取K熵及其可预报时间的估计

对广州１９０８－１９８０年的月平均气温资料，在延拓的ｎ维相空间中直接提取Ｋ熵，得到该序列的Ｋ熵值为０．１８１９，由此得到，月平均气温的平均可预报时间Ｔ－１／Ｋ，约为６个月。     

从时间序列中提取维数信息

作者介绍了分形和分维的概念、性质和意义，重点讨论了从一维时间序列中提取维数信息的方法，并给出了一些在天气和气候中的应用。     

从时间序列中提取维数信息

作者介绍了分形和分维的概念、性质和意义，重点讨论了从一维序列中提取维数信息的，并给出了一些在天气了气候中的应用。     

自然气候变异与人为气候变化对径流影响研究进展

 在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上,将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征;第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题,分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响,而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响,从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上,为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。     

自然气候变异与人为气候变化对径流影响研究进展

在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上,将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征;第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题,分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响,而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响,从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上,为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。     

南极地区地面温度序列的建立及研究

分析了南极地区自１８９５年以来考察队零散观测和少数考察站的温度资料，结合国际地球物理年以后连续观测的温度资料，建立了近百年来年平均气温序列并计算了其变化趋势。结果表明：南极地区的变暖趋势十分明显，气温比上个世纪末至少增加了１℃。     

南极地区地面温度序列的建立及研究

分析了南极地区自１８９５年以来考察队零散观测和少数考察站的温度资料，结合国际地球物理年以后连续观测的温度资料，建立了近百年来年平均气温序列并计算了其变化趋势。结果表明：南极地区的变暖趋势十分明显，气温比上个世纪末至少增加了１℃。     

Adaptation: Sensitivity to Natural Variability, Agent Assumptions and Dynamic Climate Changes

The role of adaptation in impact assessment and integrated assessment of climate policy is briefly reviewed. Agriculture in the US is taken as exemplary of this issue. Historic studies in which no adaptation is assumed (so-called "dumb farmer") versus farmer-agents blessed with perfect foresight (so-called "clairvoyant farmer") are contrasted, and considered limiting cases as compared to "realistic farmers." What kinds of decision rules such realistic farmer-agents would adopt to deal with climate change involves a range of issues. These include degrees of belief the climate is actually changing, knowledge about how it will change, foresight on how technology is changing, estimation of what will happen in competitive granaries and assumptions about what governmental policies will be in various regions and over time. Clearly, a transparent specification of such agent-based decision rules is essential to model adaptation explicitly in any impact assessment. Moreover, open recognition of the limited set of assumptions contained in any one study of adaptation demands that authors clearly note that each individual study can represent only a fraction of plausible outcomes. A set of calculations using the Erosion Productivity Impact Calculator (EPIC) crop model is offered here as an example of explicit decision rules on adaptive behavior on climate impacts. The model is driven by a 2xCO₂ regional climate model scenario (from which a "mock" transient scenario was devised) to calculate yield changes for farmer-agents that practice no adaptation, perfect adaptation and 20-year-lagged adaptation, the latter designed to mimic the masking effects of natural variability on farmers' capacity to see how climate is changing. The results reinforce the expectation that the likely effects of natural variability, which would mask a farmer's capacity to detect climate change, is to place the calculated impacts of climate changes in two regions of the US in between that of perfect and no adaptation. Finally, the use of so-called "hedonic" methods (in which land prices in different regions with different current average climates are used to derive implicitly farmers' adaptive responses to hypothesized future climate changes) is briefly reviewed. It is noted that this procedure in which space and time are substituted, amounts to "ergodic economics." Such cross-sectional analyses are static, and thus neglect the dynamics of both climate and societal evolution. Furthermore, such static methods usually consider only a single measure of change (local mean annual temperature), rather than higher moments like climatic variability, diurnal temperature range, etc. These implicit assumptions in ergodic economics make use of such cross-sectional studies limited for applications to integrated assessments of the actual dynamics of adaptive capacity. While all such methods are appropriate for sensitivity analyses and help to define a plausible range of outcomes, none is by itself likely to define the range of plausible adaptive capacities that might emerge in response to climate change scenarios.     

Evaluation of Linear and Non-Linear Downscaling Methods in Terms of Daily Variability and Climate Indices: Surface Temperature in Southern Ontario and Quebec,Canada

We downscaled atmospheric reanalysis data using linear regression and Bayesian neural network (BNN) ensembles to obtain daily maximum and minimum temperatures at ten weather stations in southern Quebec and Ontario, Canada. Performance of the linear and non-linear downscaling models was evaluated using four different sets of predictors, not only in terms of their ability to reproduce the magnitude of day-to-day variability (i.e., “weather,” mean absolute error between the daily values of the predictand(s) and the downscaled data) but also in terms of their ability to reproduce longer time scale variability (i.e., “climate,” indices of agreement between the predictand's observed annual climate indices and the corresponding downscaled values). The climate indices used were the 90th percentile of the daily maximum temperature, 10th percentile of the daily minimum temperature, number of frost days, heat wave duration, growing season length, and intra-annual temperature range.

Our results show that the non-linear models usually outperform their linear counterparts in the magnitude of daily variability and, to a greater extent, in annual climate variability. In particular, the best model simulating weather and climate was a BNN ensemble using stepwise selection from 20 reanalysis predictors, followed by a BNN ensemble using the three leading principal components from the aforementioned predictors. Finally, we showed that, on average, the first three indices presented higher skills than the growing season length, number of frost days, and the heat wave duration.     

我国东西部地区地气温差的年代际变化特征

利用1960~2006年我国地温、气温逐日4个时次[02:00(北京时间,下同)、08:00、14:00和20:00]的台站观测资料,计算并分析了我国东南、西北地区各季地气温差的年代际变化特征。分析结果表明:我国东南部地区各季地气温差在20世纪70年代末以前,大部分年份偏高,高于平均值,而在20世纪70年代末以后,我国东南部地区各季地气温差偏低,在夏季和冬季表现尤为明显。我国西北地区春季和夏季地气温差在20世纪70年代末以前大部分年份偏低,低于平均值;而在20世纪70年代末以后,地气温差则大部分年份明显偏高。我国西北地区秋季地气温差的年代际变化特征不明显,而冬季地气温差的年代际变化趋势与春夏季相反,在20世纪70年代末以前大部分年份偏高,高于平均值,而在20世纪70年代末以后偏低。另外,发现地温和气温对我国东南、西北地区各季地气温差的年代际变化在各季所起的贡献作用不同。     

中国冬季月地面气温的年际变化

基于观测资料和再分析资料,对我国冬季各月地面气温的年际变异时空演变以及它们之间的相互关系、相关的环流异常特征进行了统计诊断分析,并对大气内部的影响过程和机制进行解释。我国冬季各月地面气温的主要年际变异模态是除青藏高原地区外的全国一致型,其次为南北反号分布型。我国冬季1月与2月气温的主要年际变异模态之间存在显著的同相变化关系,而它们与前期12月气温的主要变异型存在一定程度的反相变化关系。我国冬季各月地面气温主要年际变异模态又与欧亚大陆更大范围的高纬—中低纬度地区气温的反号变异型直接相关。与我国冬季各月大范围的地面气温变异相关的温度异常信号存在于深厚的对流层,其中异常信号在地面最显著,其强度随高度逐渐衰减。地表温度异常可以通过地表向上长波辐射通量异常来影响近地面乃至更高层次的气温异常。在冬季各月,欧亚大陆北部上空对流层各层出现的明显西风异常加强,使得高纬度的冷空气南侵活动减弱,从而造成我国乃至更大范围且垂直深厚的气温暖异常。