Bias-Corrected Short-Range Ensemble Forecasts for Near-Surface Variables during the Summer Season of 2010 in Northern China

A running mean bias （RMB） correction ap- proach was applied to the forecasts of near-surface variables in a seasonal short-range ensemble forecasting experiment with 57 consecutive cases during summer 2010 in the northern China region. To determine a proper training window length for calculating RMB, window lengths from 2 to 20 days were evaluated, and 16 days was taken as an optimal window length, since it receives most of the benefit from extending the window length. The raw and 16-day RMB corrected ensembles were then evaluated for their ensemble mean forecast skills. The results show that the raw ensemble has obvious bias in all near-surface variables. The RMB correction can remove the bias reasonably well, and generate an unbiased ensemble. The bias correction not only reduces the ensemble mean forecast error, but also results in a better spreaderror relationship. Moreover, two methods for computing calibrated probabilistic forecast （PF） were also evaluated through the 57 case dates： 1） using the relative frequency from the RMB-eorrected ensemble; 2） computing the forecasting probabilities based on a historical rank histogram. The first method outperforms the second one, as it can improve both the reliability and the resolution of the PFs, while the second method only has a small effect on the reliability, indicating the necessity and importance of removing the systematic errors from the ensemble.     

公元1000—2000年中国北方地区极端干旱事件序列重建与分析

利用历史文献记录重建了公元1000—2000年中国北方地区极端干旱事件序列,在此基础上分析极端干旱事件的发生特征与规律。研究得出以下结论:(1)极端干旱事件在公元1000—2000年中存在200年左右的周期波动。在15世纪中期、17世纪初期和18世纪末期存在3次极端干旱事件高发期。(2)极端干旱事件的变动与中国东部地区干湿变化相一致,在偏干的时期极端干旱事件发生次数上升,在偏湿时则下降。(3)在中世纪暖期和现代暖期,温度愈高,极端干旱事件偏多;而在小冰期,则温度偏低的时期极端干旱事件多发。(4)西风带影响下的非季风区,干湿变化与极端干旱事件的关系与华北季风区相反,这可能与所谓的“丝绸之路遥相关”和NAO(NorthAtlanticOscillation,北大西洋涛动)的影响有关。     

中国北方地区农业干旱脆弱性评价

在调查和分析中国北方地区农业生产现状的基础上,选择水资源、农业经济、社会和防旱抗旱能力4个准则层共16个指标构建农业干旱脆弱性评价指标体系。运用主成分分析法对高维变量系统进行有效降维,根据方差贡献率建立中国北方地区农业干旱脆弱性评价模型,获得中国北方地区水资源、农业经济、社会和防旱抗旱能力脆弱性评价结果,获得各省(自治区、直辖市)干旱脆弱性分级阈值和区划。结果表明:(1)通过主成分分析得到农业经济、水资源、防旱抗旱能力、社会等5个主成分,方差贡献率分别为41.99%、19.25%、14.06%、8.07%和5.32%。(2)中国北方地区农业干旱脆弱性从小到大依次为北京、天津、山东、辽宁、吉林、山西、内蒙古、安徽、河北、河南、陕西、宁夏、青海、黑龙江、新疆和甘肃。     

红鳍东方鲀养殖技术研究现状及展望

<正>红鳍东方鲀(Takifugu rubripes),属鲀形目(Tetraodontiformers)、鲀亚目(Tetraodontoidei)、鲀科(Tetraodontidae)、东方鲀属(Takifugu),俗称河鲀、廷巴、腊头、龟鱼等,为近海底层食肉性鱼类,主要分布于北太平洋西部的日本、朝鲜半岛和中国沿海[1]。因其味道鲜美、肉质细嫩,经济价值高昂,在中国北方地区和日本、韩国等形成养殖规模。目前国内外对红     

近58 a中国北方地区极端气温时空变化及影响因素分析

基于北方地区404个气象站1960—2017年逐日最高气温、最低气温资料,应用线性倾向估计法、Mann-Kendall法、滑动t检验法、累积距平法和相关分析法,分析了极端气温的时空变化特征,并探讨了气温指数的影响因素。研究表明:极端气温暖指数和极值指数呈上升趋势,冷指数和气温日较差呈下降趋势;变化幅度中冷指数大于暖指数,夜指数大于昼指数,西北地区极端气温指数变化幅度最大,东北地区最小。突变时间上,极端气温指数突变主要发生在20世纪80年代和90年代,暖指数和极高值指数晚于冷指数和极低值指数,东北地区极端气温指数突变时间最早,西北地区最晚,突变后极端暖事件和气温极值事件进入多发阶段,极端冷事件进入少发阶段。1988—2012年极端气温指数的变化响应了全球变暖停滞现象。多数极端气温指数与经纬度、海拔高度显著相关。北极涛动(AO)指数对极端气温的影响最强,对冷指数影响最明显。气溶胶光学厚度与多数冷指数呈负相关,而与多数暖指数呈正相关。     

中国北方地区沙漠与河流景观格局

本文运用景观生态学原理,借助ArcGIS技术,选择中国北方10个流域及其12个沙漠/沙地,并以西部的和田河和东部的西辽河为典型研究区,在流域与沙区、河道与沙丘两个尺度上,选取景观破碎度指数、景观多样性指数等指标,探讨中国北方干旱、半干旱区沙漠/沙地景观与廊道景观(河流)的空间镶嵌格局特征。结果表明：在流域与沙区尺度上,内流区较外流区沙区景观类型复杂,景观破碎度较小,外流区沙区景观结构较为相似;内流区沙区景观指数自西向东呈现出“景观破碎度递增、景观结构复杂性递减”的规律。在河道与沙丘尺度上,在缓冲带范围内,和田河较西辽河沙丘景观类型复杂,景观破碎度较小;景观指数随河道距离的变化呈现出“景观破碎度随距河道距离的加大而逐渐递减,丰富度指数随距河道距离的加大而呈阶梯状递增”的规律;从沙丘斑块类型景观指数上看,西辽河以固定、半固定的简单型沙丘为主,和田河以流动的综合型沙丘为主。主导的沙丘类型景观距离河道越远,面积比例越小,不同沙丘类型的水平景观破碎度随河道距离递减。     

利用华北地区承压井水位动态反演含水层体应变

The change of the confined aquifer level reflects the pore pressure change, and the pore pressure change of the aquifer is closely related to the aquifer pressure. This paper uses the tidal response of the well water level data in the North China region to calculate the tidal factor of each well and extract the effective water trend information. Then, the volumetric strain of an existing confined aquifer well in the North China region is inverted, and the contour maps are plotted on a half-year scale from 2009 to 2012. Results show that it can reflect the state of stress and strain in deep crust to a certain extent in the North China region.     

全面推进供热计量改革——访住房和城乡建设部副部长仇保兴

在雾霾盛行的当下,供热采暖再度成为各方关注焦点。供热采暖是建筑能耗的大户,中国北方地区冬季供热采暖每年消耗煤炭1．5亿多吨标煤,占全国建筑能耗40％以上。     

近50年华北地区极端气候分析

Climate extremes for agriculture-pasture transitional zone, northem China, are analyzed on the basis of daily mean temperature and precipitation observations for 31 stations in the period 1956-2001. Analysis season for precipitation is May-September, i.e., the rainy season. For temperature is the hottest three months, i.e., June through August. Heavy rain events, defined as those with daily precipitation equal to or larger than 50 mm, show no significant secular trend. A jump-like change, however, is found occurring in about 1980. For the period 1980-1993, the frequency of heavy rain events is significantly lower than the previous periods. Simultaneously, the occurring time of heavy rains expanded, commencing about one month early and ending one month later. Long dry spells are defined as those with longer than 10 days without rainfall. The frequency of long dry spells displays a significant (at the 99% confidence level) trend at the value of 8.3% /10a. That may be one of the major causes of the frequent droughts emerging over northern China during the last decades. Extremely hot and low temperature events are defined as the uppermost 10% daily temperatures and the lowest 10% daily temperatures, respectively. There is a weak and non-significant upward trend in frequency of extremely high temperatures from the 1950s to the mid-1990s. But the number of hot events increases as much as twice since 1997. That coincides well with the sudden rise in mean summer temperature for the same period. Contrary to that, the fiequency of low temperature events have been decreasing steadily since the 1950s, with a significant linear trend of-15%/10a.     

中国北方地区水资源短缺

中国地质调查局近日发布了中国地下水资源与环境调查报告。调查结果表明，中国目前人畜用水短缺，南北方由于地域差异，水资源差异明显。