Decreasing predictability as a precursor indicator for abrupt climate change

Abrupt climate change has an important impact on sustainable economic and social development, as well as ecosystem. However, it is very difficult to predict abrupt climate changes because the climate system is a complex and nonlinear system. In the present paper, the nonlinear local Lyapunov exponent (NLLE) is proposed as a new early warning signal for an abrupt climate change. The performance of NLLE as an early warning signal is first verified by those simulated abrupt changes based on four folding models. That is, NLLE in all experiments showed an almost monotonous increasing trend as a dynamic system approached its tipping point. For a well-studied abrupt climate change in North Pacific in 1976/1977, it is also found that NLLE shows an almost monotonous increasing trend since 1970 which give up to 6 years warning before the abrupt climate change. The limit of the predictability for a nonlinear dynamic system can be quantitatively estimated by NLLE, and lager NLLE of the system means less predictability. Therefore, the decreasing predictability may be an effective precursor indicator for abrupt climate change.

     

松辽盆地青山口组一段油页岩成矿条件及有利目标区分析

基于钻井、测井、地震及分析化验资料,开展了松辽盆地青山口组一段油页岩成矿条件及有利目标区分析。研究发现,松辽盆地青山口组一段油页岩最大厚度达15m;埋深几十米～2 000m,盆地东南部农安-登娄库一带埋深在500米以浅。将青山口组划分出3个三级沉积层序,青一段油页岩形成于SQ1层序下降半旋回,为深湖相沉积物,油页岩分布受该时期深湖相沉积范围的控制。根据研究区整体地质勘查程度,选取油页岩埋深和油页岩厚度为主要评价指标,并以含油率作为参考指标,建立了青一段油页岩有利目标区优选方案,确定了A类选区为农安-增盛-长春岭-朝阳沟勘查区和白城东北部勘查区,B类选区为登娄库背斜带南部地区,C类选区为农安-增盛-长春岭-朝阳沟勘查区外围。     

松辽盆地昌德地区营城组火成岩气藏储层特征及其控制因素

松辽盆地昌德地区火山岩储层以酸性岩为主,主要岩石类型为熔结凝灰岩和凝灰岩,与国内其他含油气盆地的火山岩储层明显不同。宏观上岩性较致密,岩心观察仅见构造裂缝和溶蚀孔,局部见溶蚀洞,显微镜下观察储集空间类型多样,发育粒内溶孔、晶内熔孔、晶间微孔、构造微裂缝、炸裂缝和收缩缝等。火山岩厚度普遍较薄,其中芳深9井区火山岩厚度最大,最厚仅为75m。从岩相类型看,芳深9井附近为爆发相,其他地区为溢流相。研究区火山岩为低孔低渗储层,岩性和岩相与物性关系密切,同时控制着原生孔隙的形成。后期的成岩改造,包括构造活动、溶蚀作用等决定了次生孔隙的发育程度,构造运动产生的裂缝是该区储层得以改善的主要因素,而后期充填作用破坏了储层的储集性能。火山口附近爆发相与溢流相的叠合区是天然气勘探的有利目标。     

甘肃北山地区黑山铜镍矿化基性—超基性杂岩体 SHRIMP锆石U-Pb定年及其地质意义

黑山铜镍矿床位于塔里木板块东北部的北山裂谷带内,庙庙井－双鹰山深大断裂南侧,含矿基性—超基性复式杂岩体侵位于青白口系大豁落山组和寒武系双鹰山组中。矿化主要赋存于杂岩体内的橄榄岩和角闪辉长岩内。采用锆石离子探针微区原位（SHRIMP）法获得矿化角闪辉长岩中锆石的U-Pb年龄为374.6Ma±5.2Ma,表明该含矿杂岩体的侵位及矿化作用均发生于晚泥盆世。这一年龄数据的获得不仅对重新认识北山地区的地质构造演化具有重要意义,而且为北山地区开展铜镍矿找矿提出了新方向。     

Assessment of changes in the area of the water conservation forest in the Qilian Mountains of China’s Gansu province, and the effects on water conservation

The Qilian Mountains water conservation forest in Gansu province is an important ecological barrier surrounding the oasis in China’s Hexi Corridor. The water they provide is the basis for the existence and sustainable socioeconomic development of those oases. As a result of unsustainable use of the water conservation forest until the 1980s, the oasis ecosystems of the Hexi region were seriously damaged, and the oasis areas experienced deterioration of their ecological environment. In this paper, Landsat images were used to monitor the temporal and spatial changes in area of water conservation in Qilian Mountains of China’s Gansu province and to assess the effect on water conservation by analyzed relationship between water conservation forest area, climatic data and hydrological data. The results showed that the forest covered 15.1% of the study area in 2007 and has followed different trends during the study period. From 1978 to 1990, the forest area decreased; however, from 1990 to 2007, the forest area increased, with a faster rate of increase from 1990 to 2000, and the rate of increase averaged 2,733.89 ha per year since 1990. The water conservation forest appears to play an important role in flood control, runoff regulation, the prevention of soil erosion, and water conservation; and these benefits increase with an increasing area of forest.     

基于VAD技术的迭代法在实测多普勒速度缺测区域的填补研究

多普勒天气雷达径向速度场缺测区域的存在是影响速度二次产品算法精确度的重要因素,在实际风场为线性分布的假设条件下,文中详细介绍了一种基于VAD技术的迭代填补技术.在合理考虑迭代约束条件的情况下,应用实测多普勒速度数据,根据缺测区域类型随机制造非连续累积10°-180°缺口的缺测区域和连续累积10°-180°缺口的缺测区域...     

An assessment of the surface climate in the NCEP climate forecast system reanalysis

This paper analyzes surface climate variability in the climate forecast system reanalysis (CFSR) recently completed at the National Centers for Environmental Prediction (NCEP). The CFSR represents a new generation of reanalysis effort with first guess from a coupled atmosphere?Cocean?Csea ice?Cland forecast system. This study focuses on the analysis of climate variability for a set of surface variables including precipitation, surface air 2-m temperature (T2m), and surface heat fluxes. None of these quantities are assimilated directly and thus an assessment of their variability provides an independent measure of the accuracy. The CFSR is compared with observational estimates and three previous reanalyses (the NCEP/NCAR reanalysis or R1, the NCEP/DOE reanalysis or R2, and the ERA40 produced by the European Centre for Medium-Range Weather Forecasts). The CFSR has improved time-mean precipitation distribution over various regions compared to the three previous reanalyses, leading to a better representation of freshwater flux (evaporation minus precipitation). For interannual variability, the CFSR shows improved precipitation correlation with observations over the Indian Ocean, Maritime Continent, and western Pacific. The T2m of the CFSR is superior to R1 and R2 with more realistic interannual variability and long-term trend. On the other hand, the CFSR overestimates downward solar radiation flux over the tropical Western Hemisphere warm pool, consistent with a negative cloudiness bias and a positive sea surface temperature bias. Meanwhile, the evaporative latent heat flux in CFSR appears to be larger than other observational estimates over most of the globe. A few deficiencies in the long-term variations are identified in the CFSR. Firstly, dramatic changes are found around 1998?C2001 in the global average of a number of variables, possibly related to the changes in the assimilated satellite observations. Secondly, the use of multiple streams for the CFSR induces spurious jumps in soil moisture between adjacent streams. Thirdly, there is an inconsistency in long-term sea ice extent variations over the Arctic regions between the CFSR and other observations with the CFSR showing smaller sea ice extent before 1997 and larger extent starting in 1997. These deficiencies may have impacts on the application of the CFSR for climate diagnoses and predictions. Relationships between surface heat fluxes and SST tendency and between SST and precipitation are analyzed and compared with observational estimates and other reanalyses. Global mean fields of surface heat and water fluxes together with radiation fluxes at the top of the atmosphere are documented and presented over the entire globe, and for the ocean and land separately.     

电线积冰物理过程与数值模拟研究进展

电线积冰对人们的日常生活、电力系统、通信系统等造成了巨大的影响,人们越来越关注电线积冰的形成条件及物理过程,包括气象条件、气流动力学、液滴运动轨迹以及热力学过程。通过外场观测、室内实验和数值模拟研究的不断开展,揭示出电线积冰质量增长过程决定于云降水粒子谱分布、碰撞效率、黏性率、冻结率、碰撞速度和角度等微物理参数,这些参数又受控于降水率、云雾含水量、温度、湿度、风向、风速等宏观气象条件。通过数值模式已可进行电线积冰量和积冰持续时间的定量研究和预测,进而在开发垂冰模式和形态模式等方面也取得了新的进展。在总结过去60多年来电线积冰物理机制和数值模拟研究主要成果的基础上,对开展进一步的深入研究进行了展望。     

中国大陆现代构造应力场与强震活动

依据应力性状和力源特征,中国大陆现代构造应力场可划分为四级应力区.它们分别是2个一级应力区、4个二级应力区、5个三级应力区和26个四级应力区.通过分析中国大陆现代构造应力分区与强震活动之问的关系,初步获得以下结论:①构造应力作用强烈和复杂的地区是强震频发的地区;②应力区边界是强震集中发生的地带;③应力方向、应力结构类型...     

天津轨道交通对地磁观测干扰的影响研究

直流牵引城市轨道交通系统在运行过程中产生的磁场对我国大城市周边地磁台站的观测数据产生较为严重的干扰.城市轨道交通运行过程中产生泄露电流是产生干扰的重要原因.本文以真空中的线电流磁场计算模型为基础,通过简化的远场磁场干扰模型对天津地铁轨道交通干扰进行理论建模.该模型计算简洁高效.通过对模型的数值模拟,获得了干扰随距离衰减...