Can Artificial Climate Trends in Global Reanalysis be Reduced by Dynamical Downscaling:A Case Study of China          下载免费PDF全文

ZHAO Tian-Bao  ZHAO De-Ming 《大气和海洋科学快报》2011,4(1):30-35

In this study,the ability of dynamical downscaling for reduction of artificial climate trends in global reanalysis is tested in China.Dynamical downscaling is performed using a 60-km horizontal resolution Regional Integrated Environmental Model System (RIEMS) forced by the NCEP-Department of Energy (DOE) reanalysis II (NCEP-2).The results show that this regional climate model (RCM) can not only produce dynamically consistent fine scale fields of atmosphere and land surface in the regional domain,but it also has the ability to minimize artificial climate trends existing in the global reanalysis to a certain extent.As compared to the observed 2-meter temperature anomaly averaged across China,our model can simulate the observed inter-annual variation and variability as well as reduce artificial climate trends in the reanalysis by approximately 0.10 C decade 1 from 1980 to 2007.The RIEMS can effectively reduce artificial trends in global reanalysis for areas in western China,especially for regions with high altitude mountains and deserts,as well as introduce some new spurious changes in other local regions.The model simulations overestimated observed winter trends for most areas in eastern China with the exception of the Tibetan Plateau,and it greatly overestimated observed summer trends in the Sichuan Basin located in southwest China.This implies that the dynamical downscaling of RCM for long-term trends has certain seasonal and regional dependencies due to imperfect physical processes and parameterizations.  相似文献   

基于DERF的SD方法预测月降水和极端降水日数   总被引：3，自引：1，他引：2       下载免费PDF全文

刘绿柳  孙林海  廖要明  杜良敏  李想 《应用气象学报》2011,22(1):77-85

针对动力气候模式对区域或更小空间尺度内的日降水预测技巧偏低的问题,应用最优子集回归 (OSR) 方法对国家气候中心业务化的月动力气候模式 (DERF) 输出的高度场、风场和海平面气压场进行降尺度处理用于降水预测,旨在提高预测准确率。1982—2006年交叉检验结果表明:OSR方法能显著提高降水预测技巧,其中11~40 d改善效果最为显著。在此基础上,应用一步法和两步法两种统计降尺度方法预测极端降水日数,交叉检验结果表明:两种方法均优于随机预测,冬季两步法预测技巧略高于一步法,夏季一步法略优于两步法。综合认为OSR,OSR结合随机天气发生器 (WG) 两种统计降尺度方法对月尺度降水或极端降水日数的预测均具有较高的技巧,可作为短期气候预测的重要参考信息。  相似文献   

不同海域影响热带气旋强度变化的环境动力因素对比   总被引：1，自引：0，他引：1  

王喜  余锦华 《热带气象学报》2011,27(3):387-386

利用1982-2007年NCEP/NCAR再分析资料、月平均海平面温度(SST)资料和西北太平洋、北大西洋以及北印度洋热带气旋(TC)资料,对比分析了环境动力因素对不同海域TC强度在不同时间尺度变化的影响.结果表明,在各时间尺度上,TC强度变化与垂直风切变变化有密切的联系.在西北太平洋,使TC过程强度增强或减弱的风切变...  相似文献   

区域经济发展动力系统的构建与运行机制研究   总被引：3，自引：0，他引：3  

谷国锋 《地理科学》2008,28(3):320-324

区域经济发展需要动力,解决动力问题一直是区域经济学、经济地理学、发展经济学等学科长期研究的重点领域。单一动力对区域经济发展能够产生一定的功效,但缺乏系统动力是区域经济发展中一个普遍存在的问题。在科学发展观背景下,通过对区域经济发展要素的分类与综合分析,提出了"合动力网络"的概念,以自组织结构动力、技术创新动力、制度创新动力和文化动力为子系统,初步构建了区域经济发展的动力系统,并分析了动力系统及其子系统的相互作用关系和运行机制。  相似文献   

A stability analysis of a conduit flow model for lava dome eruptions     

M. Nakanishi  T. Koyaguchi 《Journal of Volcanology and Geothermal Research》2008

Periodic variations in magma discharge rate and ground deformation have been commonly observed during lava dome eruptions. We performed a stability analysis of a conduit flow model by Barmin et al. [Barmin, A., Melnik, O., Sparks, R.S.J., 2002. Periodic behavior in lava dome eruptions. Earth and Planetary Science Letters 199 (1-2), 173–184], in which the periodic variations in magma flow rate and chamber pressure are reproduced as a result of the temporal and spatial changes of the magma viscosity controlled by the kinetics of crystallization. The model is reduced to a dynamical system where the time derivatives of the magma flow rate (dQ/dt) and the chamber pressure (dP/dt) are functions of Q and P evaluated at a shifted time t − t_?. Here, the time delay t_? represents the time for the viscosity of fluid particle to increase in a conduit. The dynamical system with time delay is approximated by a simple two-dimensional dynamical system of Q and P where t_? is given as a parameter. The results of our linear stability analyses for these dynamical systems indicate that the transition from steady to periodic flow depends on nonlinearities in the steady state relation between Q and P. The steady state relation shows a sigmoidal curve in Q − P phase plane; its slope has negative values at intermediate flow rates. The steady state solutions become unstable, and hence P and Q oscillate periodically, when the negative slope of the steady state relation ([dP/dQ]_S) exceeds a critical value; that is [dP/dQ]_S < − t_?γ/(2V_ch), where V_ch is the chamber volume and γ is an elastic constant which is related to the rigidity of chamber wall. We also found that the period and the pattern of oscillation of the conduit flow primarily depend on a quantity defined by LV_ch/r⁴, where L is the conduit length and r is the conduit radius.  相似文献   

预应力混凝土连续弯箱梁桥动力特性分析与试验研究     

孟会英  陈秀云  雷世发 《世界地震工程》2008,24(1):128-131

通过某预应力混凝土连续弯箱梁桥的有限元分析,并借助脉动试验和跑车试验,对预应力混凝土连续弯箱梁桥的动力特性进行研究.结果表明,该桥自振频率略高于理论计算值,结构动力刚度满足设计要求.为研究弯曲程度对连续弯箱梁桥动力特性的影响,对圆心角从0°到76°的弯桥进行计算,结果表明,随着圆心角的增大,该桥纵向频率逐渐增大,而横向频率逐渐减小.  相似文献   

Challenging emotions     

Katy Bennett 《Area》2009,41(3):244-251

This paper contributes to work on emotional geographies by engaging with Liz Bondi's focus on relationality and the challenge to geographers to explore how their emotion might connect with the feelings of their subjects. Through the lens of a focus group meeting that created confusing feelings, it shows the hurdles that geographers face when they engage with practices developed in a psychotherapeutic setting. The paper is not so much a critique, more a desire to continue the conversation regarding how to approach and adopt psychotherapy's theory of practice in a research context .  相似文献   

半干旱区植被风沙动力过程耦合研究:Ⅰ.模型   总被引：5，自引：3，他引：2  

李振山  王怡  贺丽敏 《中国沙漠》2009,29(1):23-30

从植被生长和风沙活动之间的相互作用机制出发,建立了植被-风沙动力耦合模型。模型包括生物量动力学方程和风蚀量动力学方程。生物量动力学方程主要考虑了植被生产潜力在植被覆盖地表和非植被覆盖地表上的转化、生物量自身消耗以及风蚀量对生物量的影响;风蚀量动力学方程主要考虑风蚀潜力在流沙地表和非流沙地表上的转化以及生物量对风蚀量的影响。根据我国北方半干旱地区相关研究成果对模型中的参数取值进行了探讨,以便进行模拟和应用研究。  相似文献   

肥城矿区地下水资源分析研究   总被引：1，自引：0，他引：1  

王则才  张兆强 《煤田地质与勘探》2006,34(6):57-59

为正确认识和解决地下水资源开发利用中存在的问题,通过检测地下水水动力条件和水化学条件的变化,对肥城矿区地下水资源现状进行了科学分析。研究认为:肥城盆地大气降水量的大小将直接影响来年地下水位的高低;四灰和五灰岩溶水中的氟离子含量普遍较高;第四系孔隙水普遍遭受了氮污染,其硝酸盐含量较高,从而使奥陶系含水层中也含有较高的硝酸盐组分;地表水及矿坑水硬度、矿化度都超标,同时存在大量硫酸根;矿井水经沉淀去除悬浮物后,可以达到污水综合排放、景观用水及煤矿井下防尘用水标准。另外,聚类分析和因子分析表明,五灰水与奥灰水普遍存在密切的水力联系。   相似文献   

吉林中部平原区地下水温动态变化影响因素的关联度分析   总被引：6，自引：0，他引：6  

方燕娜  廖资生  陈洪艳  董维红 《吉林大学学报(地球科学版)》2006,36(1):66-72

以吉林中部平原区为例,分析了孔隙潜水、孔隙承压水以及白垩系孔隙裂隙承压水温度的多年变化特征,并采用灰色关联度分析方法,确定了各含水层地下水温度与地下水埋深、气温、降水量之间的关联性,分析了影响其变化的主要因素。结果表明,对于3组含水层,从20世纪80年代初至2001年的近20年间,地下水温度都有不同程度的上升。对于孔隙潜水和孔隙承压水,地下水温度呈上升变化的本质原因是全球气候逐年变暖,而地下水活动和大气降水的增强起到了促进作用,特别是对孔隙承压水温度的上升作用更加明显;对于白垩系孔隙裂隙承压水,其温度呈上升变化则主要是由该含水层被普遍超采所引起的。  相似文献