英文文献：On the Systemic Nature of Weather Risk-论天气风险的系统性
英文文献作者：Xu, Wei,Filler, Gunther,Odening, Martin,Okhrin, Ostap
英文文献摘要：
Systemic weather risk is a major obstacle for the formation of private (nonsubsidized) crop insurance. This paper explores the possibility of spatial diversification of insurance by estimating the joint occurrence of unfavorable weather conditions in different locations. For that purpose copula methods are employed that allow an adequate description of stochastic dependencies between multivariate random variables. The estimation procedure is applied to weather data in Germany. Our results indicate that indemnity payments based on temperature as well as on cumulative rainfall show strong stochastic dependence even at a national scale. Thus the possibility to reduce risk exposure by increasing the trading area of the insurance is limited. Irrespective of their economic implications our results pinpoint the necessity of a proper statistical modeling of the dependence structure of multivariate random variables. The usual approach of measuring stochastic dependence with linear correlation coefficients turned out to be questionable in the context of weather insurance as it may overestimate diversification effects considerably.

系统性气候风险是私人(非补贴)农作物保险形成的主要障碍。本文通过对不同地点共同发生的不利天气条件的估计，探讨了保险空间多样化的可能性。为此目的，采用了连接方法，允许充分描述随机变量之间的随机相关性。在德国，这种估算方法适用于天气数据。结果表明，即使在国家尺度上，基于温度和基于累积降雨量的赔款也表现出很强的随机依赖性。因此，通过增加保险的交易范围来减少风险暴露的可能性是有限的。不管它们的经济影响，我们的结果指出了一个适当的多元随机变量依赖结构的统计模型的必要性。通常用线性相关系数来衡量随机依赖关系的方法在天气保险中被证明是有问题的，因为它可能大大高估多样化效应。