IS THE EXTREME SNOW DEPTH RECORD FOR NORDLAND,NORWAY RELIABLE?          下载免费PDF全文

WILFRED H. THEAKSTONE 《Geografiska Annaler: Series A, Physical Geography》2016,98(4):313-323

A snow depth of 370 cm at Dunderlandsdalen in winter 1919–20 is the largest recorded at stations in Nordland, Norway. During the period 1895–1924, the average maximum annual value there was 150.4 cm; at other stations it ranged from 38.5 to 190.1 cm. The ratio of maxima at other stations to that at Dunderlandsdalen was particularly low in 1919–20. In Nordland generally, that winter's recorded precipitation was slightly above the 30‐year average, but at Dunderlandsdalen it exceeded the average by 34%. At all stations except Dunderlandsdalen, 26 Jan.–1 Feb. was a dry period; at Dunderlandsdalen, 51.7 mm was recorded. Only one day without snowfall was recorded at Dunderlandsdalen between early January and early February, but elsewhere there were few days with snowfall. The difference in snowfall frequency and snow depth at Dunderlandsdalen in 1919–20 from values recorded elsewhere in Nordland contrasts with the relationships in other winters between 1895 and 1924. No observations were made at Dunderlandsdalen in winter 1917–18. Two of the householders there died in 1916. A change of personnel making the observations may have been responsible for the data gap and for the anomalous 1919 data. Changes made to buildings or the recording site in 1917 or 1918 may have resulted in increased snow depths as a result of drifting. Maintaining a record of climatic extremes and their environmental consequences is important. Data must be accurate. In view of this, it would be sensible to regard the validity of the 370 cm Dunderlandsdalen maximum as doubtful.  相似文献   

滇中地区早前寒武纪地质研究新进展   总被引：1，自引：1，他引：0  

李静  刘桂春  刘军平  胡绍斌  曾文涛  孙柏东  张虎  邓仁宏  张志斌  刘发刚  段向东  俞赛赢  王晓峰  赵云江  周坤 《地质通报》2018,37(11):1957-1969

滇中地区中元古界"昆阳群"的地层层序是长期争议的重大基础地质问题,在一定程度上制约了地质调查工作的部署及勘查效果,也制约着滇中地区前寒武纪地质研究水平的进一步提高。云南省地质调查院在进行《云南省区域地质志》(第二版、修编)、1:5万二街等4幅区域调查子项目工作中,在前人工作成果的基础上,通过大量的野外地质调查及锆石同位素年代学研究,在滇中地区早前寒武纪地层层序及时代、重大地质事件记录、早期生命与环境协同演化等方面取得了一系列的新发现,具有重要意义。  相似文献   

基于高分二号卫星数据的煤矿区地质灾害信息提取研究          下载免费PDF全文

赵萍  李志辉  肖瑶袁峰  李晓晖 《地质科学》2018,(4):1361-1374

随着遥感数据获取技术和能力的全面提高,遥感数据呈现出明显的大数据特征。发展适应于遥感大数据的智能分析和信息挖掘技术,成为当前遥感技术研究的前沿。高分二号（GF-2）卫星数据是我国首颗自主研发的亚米级高分辨率卫星数据,具有观测幅宽、重访周期短、高辐射精度、高定位精度等优势,为未来我国地质灾害的长期、动态地监测和研究提供了高精度、稳定可靠的数据源。本文选取安徽谢桥煤矿2015年1月8日的GF-2卫星影像为研究数据,在对煤矿区主要地质灾害遥感地学分析的基础上,采用面向对象的影像分析方法对研究区由采煤活动所诱发的地质灾害信息进行自动提取。结果表明：利用GF-2卫星数据能够有效地识别地质灾害体的位置、范围、形态等空间分布特征;面向对象的自动提取方法对于煤矿区大面积的积水塌陷盆地、小规模的塌陷坑和线性的地裂缝都有很高的提取精度,识别精度达90% 以上;基于逐层剔除的思路构建的提取规则,为GF-2数据在地质灾害调查和大数据分析中的应用提供了很好的技术支持,也为其它地物目标的提取提供了参考,但在特征的选择和阈值的设定上需要具体分析。  相似文献   

关于复合型极端事件的新认识和启示          下载免费PDF全文

余荣  翟盘茂 《大气科学学报》2021,44(5):645-649

近年来,极端天气气候事件频繁发生,且常常表现为多种事件交织形成的复合型极端事件。为了更好地认识复合型极端事件,IPCC AR6基于现有的新证据评估了复合型极端事件的最新研究成果,并取得一些新认识：扩展了有关复合型极端事件的定义,重点围绕高温干旱复合型极端事件、复合洪水和野火,评估了复合型极端事件的变化特征,探讨了复合型极端事件多因子之间的依赖性,对人类活动的影响进行了归因分析并给出了未来可能的变化。这些评估结果丰富了对复合型极端事件的基本认识。但根据现有的评估可以发现,目前在复合型极端事件发生发展机理认识方面还存在不足;同时,未来仍需进一步完善跨学科跨部门跨区域研究,加强对复合型极端事件形成机理、预估及其对生态系统,经济社会影响风险的评估,提高对区域气候变化的适应能力。  相似文献   

两类El Niňo事件次年夏季长江-黄河流域降水低频特征及低频水汽输送途径差异          下载免费PDF全文

李丽平  倪语蔓  杨春艳  马晨誉 《大气科学学报》2019,42(3):420-433

利用1961年1月—2014年12月Hadley气候预测研究中心的全球海表温度(SST)资料,NECP/NCAR逐日风场、比湿等再分析资料,国家气象信息中心提供的中国753站逐日降水、160站逐月降水资料,对比分析了东部(EP)型和中部(CP)型两类El Niňo事件次年夏季长江-黄河流域降水(简记为EP型和CP型降水)低频特征,以及与之相关的低频水汽输送差异。结果表明,1)平均而言,EP型降水主要有10～20 d(最显著)以及20～30 d(次显著)低频周期;CP型降水主要有10～20 d的低频显著周期。与之相关的纬、经向水汽通量最显著低频周期也为10～20 d。2)影响EP、CP型低频降水共同的低频水汽环流系统主要有:菲律宾群岛附近的异常反气旋式水汽环流和渤海湾附近(日本东南侧)的异常气旋式(反气旋式)水汽环流。另外,影响EP(CP)型低频降水的还有来自巴尔喀什湖东北部异常气旋式水汽环流(孟加拉湾、苏门答腊岛以西的异常气旋式水汽环流对和贝加尔湖西、东两侧的异常气旋式、反气旋式环流)。3)EP型降水暖湿水汽主要源自南海,冷湿水汽主要源自西北太平洋,冷空气来自巴尔喀什湖东北部和贝加尔湖西北侧。CP型降水暖湿水汽少量来自阿拉伯海和印度洋,大量来自热带西太平洋,冷空气主要来自贝加尔湖西北侧。  相似文献   

昆明长水机场气候特征分析     

张序 《气象科学进展》2019,(1):41-45

利用昆明市1951—2010年逐日气象数据,采用回归分析法和Mann-Kendall突变分析法进行分析和检验,确定了昆明市极端降水和极端温度天气事件。在此基础上,对昆明长水机场极端天气背景下大雾天气航班安全运行开展研究,并在对比昆明长水机场与原巫家坝机场大雾特点的基础上,制定出航班安全运行的应对措施。研究表明,近几年昆明市极端温度和极端降水事件呈现增多趋势;因地形原因,长水机场出现大雾的频率远高于原巫家坝机场;大雾造成的低能见度天气背景下,航班的安全运行需要航空公司各部门的通力协作。  相似文献   

THE IMPACT OF MOUNTAIN TO BASIN WINDS ON THE DIURNAL VARIATION IN FOG OVER THE SICHUAN BASIN, CHINA     

张福颖  刘海文  朱玉祥  赵亮  段伯隆  傅宁 《热带气象学报(英文版)》2019,25(2):257-268

There is an increased demand for the accurate prediction of fog events in the Sichuan Basin (SCB) using numerical methods. A dense fog event that occurred over the SCB on 22 December 2016 was investigated. The results show that this dense fog event was influenced by the southwest of a low pressure with a weak horizontal pressure gradient and high relative humidity. This fog event showed typical diurnal variations. The fog began to form at 1800 UTC on 21 December 2016 (0200 local standard time on 22 December 2016) and dissipated at 0600 UTC on 22 December 2016 (1400 local standard time on 22 December 2016). The Weather Research and Forecasting model was able to partially reproduce the main features of this fog event and the diurnal variation in the local mountain to basin winds. The simulated horizontal visibility and liquid water content were used to characterize the fog. The mountain to basin winds had an important role in the diurnal variation of the fog event. The positive feedback mechanism between the fog and mountain to basin winds was good for the formation and maintain of the fog during the night. During the day, the mountain to basin wind displayed a transition from downslope flows to upslope flows. Water vapor evaporated easily from the warm, strong upslope winds, which resulted in the dissipation of fog during the day. The topography surrounding the SCB favored the lifting and condensation of air parcels in the lower troposphere as a result of the low height of the lifting condensation level.  相似文献   

疏勒河流域极端水文事件对极端气候的响应     

程玉菲  程文举  胡想全  金彦兆 《高原气象》2019,38(3):583-592

为了明确疏勒河流域极端水文事件对极端气候事件的响应关系,选取疏勒河流域内及其周边的托勒、敦煌、瓜州、玉门、酒泉、马鬃山等气象站点的气温、降水和蒸发的日值数据,昌马堡水文站的日径流数据,通过趋势分析、滑动平均、主成分分析等方法,分析疏勒河流域极端气候指数、极端水文事件的年际变化规律以及影响极端水文事件的因素,并明确该流域极端洪水年内分布特征。结果表明:疏勒河流域年际气温升高趋势明显,降水量呈波动变化,增加趋势不明显,而蒸发量呈下降的变化趋势。表征高温的极端气温指数呈显著上升趋势,表征低温的极端气温指数呈显著下降趋势,说明疏勒河流域气温增幅明显。极端降水指数呈显著的增加趋势。该流域极端洪水事件和频次呈上升趋势,而极端枯水事件和频次呈下降趋势。极端洪水事件主要受控于极端降水事件,特别是极端降水总量,极端高温事件对极端洪水总量的增加也有影响,而极端枯水事件主要受控于极端低温事件。此外,2000-2016年年最大洪峰流量出现的时间有由8月向7月转变的趋势。  相似文献   

内蒙古冬季极端多雪气候事件环流演变特征及季节预测信号     

高涛  乌兰  司瑶冰  关彦如  杨泽龙  任晓萌  张晓梅 《内蒙古气象》2019,(1):3-8,I0002

文章研究关注了内蒙古冬季极端多雪气候事件的季节预测问题,在对大量降水观测资料、海温及大气环流场资料进行统计、分析、研究的基础上,确定了历史上58a(1960—2017年)内蒙古冬季极端多雪和少雪气候事件样本,通过对大气环流场的对比分析发现极端多雪或少雪冬季环流场特征显著不同,分析后确定了影响内蒙古冬季降雪的主要环流系统,包括西太平洋副热带高压、极涡、东亚大槽、环流E型及南方涛动等系统。同时,探索了对这些主要环流系统具有预测意义的来自海洋和大气场的预测信号,对预测信号关键区做了标准化定量提取,确定了预测信号综合指数分段判别阈值,给出了预测概念模型,取得了较好预测效果。  相似文献   

Tectonics of the Scandian orogeny and the Western Gneiss Region in southern Norway     

F. H. Koenemann 《International Journal of Earth Sciences》1993,82(4):696-717

Two crust-forming events dominate the Precambrian history of the Western Gneiss Region (WGR) at about 1800–1600 Ma and 1550–1400 Ma. The influence of the Sveconorwegian orogeny (1200–900 Ma) is restricted to the region south of Moldefjord-Romsdalen. A series of anorthosites and related intrusives are present, possibly derived from the now-lost western margin of the Baltic craton that may have been emplaced in the WGR as an allochthonous unit before the Ordovician.The Caledonian development is split into two orogenic phases, the Finnmarkian (Cambrian — Early Ordovician) and the Scandian (Late Ordovician/Early Silurian — Devonian). The lower tectonic units west of the Trondheim Trough may be Finnmarkian nappes ; they were part of the lower plate during the Scandian continental collision. The Blåhö nappe is correlated with dismembered eclogite bodies along the coast. A regional change of nappe transport direction from 090 to 135 marks the initiation of an orogen-parallel sinistral shear component around 425 Ma. The change caused the development of a complex sinistral strike-slip system in the Trondheim region consisting of the Möre-Tröndelag Fault Zone and the Gränse contact. The latter cut the crust underneath the already emplaced Trondheim Nappe Complex, thus triggering the intrusion of the Fongen-Hyllingen igneous complex, and initiating subsidence of the Trondheim Trough, and was subsequently turned from a strike-slip zone into an extensional fault. Minor southward transport of the Trondheim Nappe Complex rejuvenated some thrusts between the Lower and the Middle Allochthon. A seismic reflector underneath the WGR is interpreted to be a blind thrust which subcrops into the Faltungsgraben. During Middle Devonian orogenic collapse, detachment faulting brought higher units, now eroded elsewhere, down to the present outcrop level, such as the Bergen and Dalsfjord nappe and the Old Red basins.  相似文献