气候变化对长江上游径流影响预估

利用第五次国际耦合模式比较计划(CMIP5)中5个气候模式在3种典型浓度路径(RCPs)下的预估结果驱动SWAT水文模型,预估了21世纪气候变化对长江上游年径流量、季节分配以及极端径流的影响。结果表明：预估的长江上游平均气温呈显著上升趋势,21世纪末较当前(1986—2005年)升高1.5~5.5℃,降水总体呈增加趋势,在21世纪30年代后高于当前气候平均值,21世纪末相对于当前增加5%~15%。流域内气候变化存在明显空间差异,金沙江和岷沱江流域气温升高和降水增加幅度均大于流域平均值。预估的长江上游年径流量及各月平均径流均有增加趋势,在21世纪30年代后高于当前多年平均值,21世纪中期增加4%~8%,21世纪末增加10%~15%。预估的径流年内分布的均匀性有所增加,但年际变化明显增大,极端旱涝事件的频率和强度明显增加。预估的各子流域径流变化对气候变化的响应也存在差异,金沙江和岷沱江流域年径流量、年际变化和年内分布变化小,对气候变化的响应表现为低敏感;嘉陵江流域、乌江流域和长江上游干流径流增加幅度大,同时极端丰枯出现的频率和程度增加显著,是气候变化响应的敏感区域。     

一次暴雨过程受不同系统影响的动力热力场结构特征

本文使用常规观测资料、卫星云图、自动气象站降水量以及0.25°×0.25°的NCEP/NCAR再分析资料,对出现在东北地区北部受不同系统影响的连续2d暴雨过程的热力和动力场结构特征展开研究。结果表明:24日为暖锋锋生暴雨,暴雨范围大;25日为台风暴雨,暴雨出现在台风移动路径上,为狭长带状。暴雨是由MCS活动造成的,每次短时强降水均与TBB低值中心相对应,台风倒槽内的MCS强度比暖锋云系内的MCS弱,但是降水强度却更大。台风安比携带大量暖湿空气,其东侧的低空急流向北输送热量和水汽,水汽辐合集中在边界层内,台风暴雨的水汽辐合强度比暖锋暴雨更强烈,所造成的雨强更大。暖锋暴雨期间,小兴安岭迎风坡地形的辐合抬升作用明显;高层强辐散及地形辐合抬升作用对暴雨有较大贡献。台风暴雨期间,低空辐合,特别是水汽辐合作用对暴雨有较大贡献;辐合区位于台风倒槽附近,倒槽表现为冷锋性质。     

基于LEAP模型的城市交通低碳发展路径研究——以广州市为例

以广州市为例,应用长期能源替代规划系统（LEAP）模型,通过设置政策情景、低碳情景和绿色低碳情景,模拟不同发展情景下广州交通领域未来的能源消费需求和CO₂排放趋势,分析城市低碳发展的方向和路径。结果显示,随着城镇化进程的加快和生产生活运输需求的增加,广州交通领域碳排放总量将持续增长,但增长速度有所放缓。政策情景下,广州交通领域的CO₂排放将于2035年左右达到峰值,严重滞后于广州市提出的碳排放总量达峰目标;低碳和绿色低碳情景下,通过加大低碳政策措施的力度,达峰时间有望分别提前到2025年和2023年。要实现城市交通的低碳发展,促进交通碳排放提前达峰,需要大力发展铁路和水路运输,全面落实公交优先发展战略,有效控制小汽车数量和出行频率,不断提高交通工具的清洁化和能效水平,逐步形成各种运输方式协调发展的综合交通运输体系,推动城市交通低碳发展。     

汕头市PM2.5的气象要素影响分析及预报研究

利用2014—2017年汕头市PM_2.5的日浓度资料、以及汕头市国家基准气象观测站的同期地面气象资料,重点分析了汕头市PM_2.5浓度的变化特征以及风、混合层厚度、降水等气象条件对PM_2.5浓度的影响,同时探讨了污染物浓度变化的成因。在此基础上,根据汕头市的气候特点,采用BP （Back-Propagation）人工神经网络方法针对汛期和非汛期分别建立了PM_2.5质量浓度预报模型。结果表明：与多数内陆城市不同,汕头市PM_2.5浓度日变化为单峰型,这与汕头地处沿海受海陆风影响有关;PM_2.5浓度日峰值出现在08时左右,除早高峰污染物排放增加的因素外,与早晨时段的低风速环境有关;PM_2.5日均浓度随着风速的增大呈现减小趋势,PM_2.5日均浓度与08时混合层厚度显著相关（相关系数为-0.143）;汕头市非汛期PM_2.5浓度比汛期高,这与汕头市的亚热带季风气候特征有关,汛期各量级降水（暴雨以上除外）对PM_2.5的清除效果无明显差别,而非汛期降水对PM_2.5浓度有明显清除作用;BP人工神经网络模型的预报效果表明,汛期和非汛期的PM_2.5级别命中率TS分别为100%和90.3%,准确指数分别为87.7%和89.9%,总体预报效果良好。不同时期预报模型出现正误差的数量和程度均大于负误差,汛期预报模型在有强降水发生时误差较大,而非汛期预报模型在有冷空气入侵时误差较大。     

An Operational Precipitable Water Vapor Retrieval Algorithm for Fengyun-2F/VISSR Using a Modified Three-Band Physical Split-Window Method

The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.     

GRAPES全球集合预报系统模式扰动随机动能补偿方案初步探究

为了体现次网格尺度能量升尺度转换过程中存在的不确定性, 文中将随机动能补偿(Stochastic Kinetic Energy Backscatter, SKEB)方案应用于GRAPES(Global/Regional Assimilation and Prediction System)全球集合预报系统(GRAPES-GEPS), 以更好地表征模式误差并且增大集合离散度。使用的SKEB方案基于具有一定时、空相关特征的随机型以及由数值扩散导致的局地动能耗散率来构造随机流函数强迫。并根据流函数与水平风速旋转分量的关系, 将SKEB方案中的流函数强迫转化为适用于GRAPES全球模式的水平风速扰动。结果表明, SKEB方案的使用一方面能够提高GRAPES对大气动能谱的模拟能力; 另一方面能够改善GRAPES-GEPS的集合离散度与集合平均误差的关系, 增加了集合离散度, 并在一定程度上减小了集合平均误差, 尤其是在热带地区这种改进更为显著。而且该方案使得热带地区连续分级概率评分(CRPS评分)显著减小。就降水预报而言, 从Brier评分与相对作用特征面积(AROC, Area under the Relative Operating Characteristics)的结果来看, SKEB方案有助于改善中国地区小雨[0.1 mm, 10 mm)、中雨[10 mm, 25 mm)与大雨[25 mm, 50 mm)量级降水的概率预报技巧, 而对暴雨[50 mm, ∞)量级降水预报技巧影响很小(24 h降水量)。总体上, 模式扰动随机动能补偿方案提高了GRAPES-GEPS的概率预报技巧。      

Sub-seasonal to Seasonal Hindcasts of Stratospheric Sudden Warming by BCC_CSM1.1(m):A Comparison with ECMWF

This study focuses on model predictive skill with respect to stratospheric sudden warming(SSW) events by comparing the hindcast results of BCC_CSM1.1(m) with those of the ECMWF's model under the sub-seasonal to seasonal prediction project of the World Weather Research Program and World Climate Research Program. When the hindcasts are initiated less than two weeks before SSW onset, BCC_CSM and ECMWF show comparable predictive skill in terms of the temporal evolution of the stratospheric circumpolar westerlies and polar temperature up to 30 days after SSW onset. However, with earlier hindcast initialization, the predictive skill of BCC_CSM gradually decreases, and the reproduced maximum circulation anomalies in the hindcasts initiated four weeks before SSW onset replicate only 10% of the circulation anomaly intensities in observations. The earliest successful prediction of the breakdown of the stratospheric polar vortex accompanying SSW onset for BCC_CSM(ECMWF) is the hindcast initiated two(three) weeks earlier. The predictive skills of both models during SSW winters are always higher than that during non-SSW winters, in relation to the successfully captured tropospheric precursors and the associated upward propagation of planetary waves by the model initializations. To narrow the gap in SSW predictive skill between BCC_CSM and ECMWF, ensemble forecasts and error corrections are performed with BCC_CSM. The SSW predictive skill in the ensemble hindcasts and the error corrections are improved compared with the previous control forecasts.     

The top 1% in U.S. metropolitan areas

Increases in U.S. income inequality are driven primarily by rapidly rising incomes of the top 1%. At the national scale, rising inequality is associated with negative consequences for economic growth and stability, a range of social problems and declining social mobility. To date, there is no or little work on the geography of the top 1% and their impact on the cities they inhabit. Using individual income data from the U.S. Census, the paper offers the first detailed analysis of the spatial distribution of the top 1% in the United States. The paper makes use of the range of socio-demographic variables attached to individual records to illustrate that the large majority of the top 1% lives in large cities and that women and ethnic minorities are largely excluded from membership in the top 1%. The widening gap between incomes at the top and bottom will thus lead to increasing gender and ethnic income inequalities. Exploratory analysis of the impact of the top 1% on the bottom 99% suggests that cities with large shares of the top 1% are characterized by higher levels of skill polarization, higher labour force participation rates and lower unemployment rates for those with little formal education and higher median incomes for the better educated. However, the paper shows that higher incomes are outstripped by higher housing costs indicating that any potential advantage trickling down from the top 1% to the bottom 99% is eroded by higher living costs. Preliminary analysis also suggests that cities with a higher share of the top 1% tend to be more segregated with potential implications for the supply, quality, access to and distribution of public local services.     

常用锂同位素地质标准物质的多接收器电感耦合等离子体质谱分析研究

锂同位素研究是非传统稳定同位素地球化学研究的前沿,已广泛应用于从地表到地幔的岩石圈及流体等固体地球科学的研究领域。准确测定锂同位素比值是应用该同位素体系的前提。本文报道了国际上7种常用地质标准物质(BHVO-2、JB-2、BCR-2、AGV-2、NKT-1、L-SVEC、IRMM-016)的锂同位素组成数据。分析中采用硝酸-氢氟酸混合酸消解岩石标准样品,通过3根阳离子交换树脂(AG50W-X8,200~400目)填充的聚丙烯交换柱和石英交换柱对锂进行分离富集,利用Neptune型多接收器电感耦合等离子体质谱(MC-ICPMS)测定锂同位素比值,使用标准-样品交叉法(SSB)校正仪器的质量分馏。实验得到这7种常用地质标准物质的锂同位素组成与测试精度(2SD)分别为:δ7LiBHVO-2—L-SVEC=4.7‰±1.0‰(n=53),δ7LiJB-2—L-SVEC=4.9‰±1.0‰(n=20),δ7LiBCR-2—L-SVEC=4.4‰±0.8‰(n=8),δ7LiAGV-2—L-SVEC=6.1‰±0.4‰(n=14),δ7LiNKT-1—L-SVEC=9.8‰±0.2‰(n=3),δ7LiL-SVEC—L-SVEC=-0.3‰±0.3‰(n=10),δ7LiIRMM-016—L-SVEC=0.0‰±0.5‰(n=10),这些数据在误差范围内与国际上已发表的数据一致。Li同位素分析精度可以达到大约0.5‰,长期的分析精度即外部重现性≤±1.0‰,达到了国际同类实验室水平。7种常用地质标准物质的锂同位素组成数据的发表为锂同位素研究提供了统一的标准,使地质样品的锂同位素数据的质量监控成为可能。在基质效应的研究中,使用不同量的IRMM-016配制的标准溶液过柱,深入探讨了样品量对锂同位素测定值的影响,结果表明,在现有测试精度下,只要分析样品的锂含量达到100μg/L,且不超过树脂的承载量,样品的锂同位素组成在误差范围内与真值吻合,样品量的大小不影响锂同位素测定结果的准确性。     

应用电感耦合等离子体质谱/光谱法研究上扬子区新华磷块岩稀土元素特征及沉积学意义

新华磷矿床是我国重要的富集稀土元素的沉积型含稀土磷块岩矿床,本文利用电感耦合等离子体质谱/光谱法(ICP-MS/AES),辅以岩矿鉴定等分析技术,结合沉积学理论研究了新华磷块岩稀土元素地球化学特征及相关问题。结果表明,新华磷块岩稀土总量(∑REEs)较高,集中值介于800×10-6~1200×10-6,其组成属轻稀土+钇型,稀土元素主要以类质同象形式存在于胶磷矿中;新华磷块岩和昆阳磷块岩具相似的REEs配分曲线和明显铈负异常,δCe介于0.28~0.36,表明上扬子区南缘成磷环境为氧化条件,且为稳定的滨浅海被动大陆边缘沉积环境;但新华磷块岩与其上覆黑色岩系REEs配分曲线迥异,后者表现出不明显的铈、铕异常,说明黑色岩系主要形成于深海-半深海静水还原环境,从梅树村期早期至晚期经历了海平面升高的过程,地层层序整体显示向上变深的沉积相变,磷块岩和黑色岩系之间的接触面可能为三级层序甚至更小层序级别的界面。这些沉积学的认识揭示了上扬子区下寒武统层序地层学意义和海相沉积环境特征,对华南早寒武世生命大爆发和层序地层学深入研究提供了证据。