2015/2016年前冬至隆冬北半球中高纬度暖冷急转及环流特征初析     

聂羽  孙冷  王东阡  李多 《气象》2016,42(10):1223-1229

2015 年12月,北半球中纬度大部地区气温明显偏高,北美多地气温突破历史同期最高值。而2016年1月,北半球中纬度地区的气温迅速转为偏低,欧洲、北美、东亚等多地发生强寒潮、暴风雪等极端天气气候事件。本文结合再分析资料和台站观测资料,通过对大气环流异常的诊断分析,初步探讨了2015/2016年冬季北半球发生暖冷急转的环流特征及可能原因。分析指出,2016年1月初,北极涛动从正位相突然转为负位相,是造成北半球中纬度气温陡降的主要原因。中高纬度阻塞活动的交替建立和崩溃也加剧了气温变化的程度。此外,在厄尔尼诺年,赤道太平洋海温偏高,赤极温差增大,易造成海气系统的不稳定,再配合以全球变暖的年代际背景,通常会造成极端性灾害事件频发。  相似文献   

青藏高原自然植被总生物量的估算与净初级生产量的潜在分布^*   总被引：32，自引：0，他引：32  

罗天祥  李文华  冷允法  岳燕珍 《地理研究》1998,17(4):337-345

以800多块样地资料及森林和草地资源调查数据为基础,按县级为单位估算了青海和西藏两省区的自然植被总生物量,分别为2.586×10⁸t和1.282×10⁹t.建立的QZNPP模型显示,随着温度的增加,生物生产量呈S型曲面递增,且其递增速率随降水量增加而加快;当年均温度0℃～10℃和年降水量400mm～1000mm时,生物生产量增长最快;当年均温度>11℃和年降水量>1 100mm时,生物生产量趋向于20t/hm²·a;在年均温度<0℃时,相对降水量的增加,生物生产量呈缓慢的递减趋势,说明这时温度是影响生物生产量的主导因子。两省区115个县的生物量现实分布图显示,生物量最高值出现在西藏墨脱,其次是西藏的察隅、波密、林芝和米林,青藏高原中部及西北部的广阔地区最低。青藏高原自然植被净初级生产量最小值为0,最大值为20t/hm²·a,全区平均为6.03t/hm²·a,低于世界陆地植被的平均水平  相似文献   

泥炭样品^14C年龄可靠性初步研究   总被引：4，自引：1，他引：4  

李汉鼎  冷雪天 《海洋地质与第四纪地质》1992,12(2):89-97

本文通过对泥炭中分离出的碱不溶物、胡敏酸、富里酸等有机组分样品及未经组分分离的泥炭原样的~(14)C年龄测定,探讨了泥炭样品~(14)C年龄可靠性问题。初步认为:低灰分、低分解的泥炭,同一层位的各组分样品的~(14)C年龄,具有较明显的一致性,低灰分泥炭碱不溶物的~(14)C年龄,大多偏老于其它组分,表明其年龄是可靠的,但高灰分泥炭的碱不溶物,其年龄往往偏年轻,而胡敏酸组分的年龄则具有相对的可靠性;富里酸是最年轻的不稳定的组分,其~(14)C年龄明显年轻而不可靠,是现代碳污染的主要来源。  相似文献   

Visualized localization and tracking of debris flow movement based on infrasound monitoring     

Dunlong Liu  Xiaopeng Leng  Fangqiang Wei  Shaojie Zhang  Yong Hong 《Landslides》2018,15(5):879-893

During the initiation and movement of debris flow, low frequency infrasound is generated and emitted with characteristics such as strong penetration, low attenuation, and a high propagation speed that is faster than the debris flow. Monitoring infrasound has been used in debris flow detection and early warning systems; however, although the current infrasound-based warning system of debris flow can provide an alarm when debris flow occurs, it cannot locate and track the movement of debris flow in real time, and cannot determine the arrival time of debris flow to its potential victims. Thus, the potential applications of low frequency infrasound in debris flow disaster prevention and reduction have not yet been fully explored. In this study, we constructed an optimal triangular monitoring array based on factors such as the terrain of the monitoring area and characteristics of infrasound propagation. Combined with the time-delay estimation method, we determined and established an acoustic source localization model based on the time difference of arrival. Furthermore, with the help of a GIS platform, a visualized localization and tracking system for debris flow movement was developed to achieve real-time monitoring of debris flow. The performance of the system on acoustic source localization was validated using a simulation test and long-term field monitoring of debris flow at Jiangjia gully in Dongchuan, Yunnan province, China. Both the simulation and field test results showed that the system has high localization accuracy and strong real-time response. The results of the monitoring system could provide more accurate warning information of debris flow to local government and residents, allowing them to take appropriate mitigation measures well in advance to reduce the loss of life and property caused by debris flows.  相似文献   

Impacts of Human Water Use on the Large-scale Terrestrial Water Cycle     

Tang Qiuhong  Huang Zhongwei  Liu Xingcai  Han Songjun  Leng Guoyong  Zhang Xuejun  Mu Mengfei 《地球科学进展》2015,30(10):1091-1099

Along with the increase of population and extraordinary economic and social development, human appropriation of freshwater supply increases rapidly. Anthropogenic activities have become an important driving factor of the large-scale terrestrial water cycle. The hydrological effects of human water use have attracted growing attention. In this paper, we briefly reviewed the recent studies addressing the anthropogenic disturbance of the large-scale terrestrial water cycle. The review focused on the direct alteration of the water cycle for human needs, with special coverage for the primary aspects of human water use such as irrigation, domestic and industrial water use, reservoir regulation and groundwater mining. The state-of-the-art parameterization schemes of human water use for macroscale land surface hydrological modeling were introduced and the limitations of the schemes were discussed. Considering the impacts of human water use on the terrestrial water cycle is currently a challenge for macroscale land surface hydrological modeling, which hinders the use of the models in assessing water resources under changing environment. Further studies are needed to understand the interactions between human and water systems, to develop integrated assessment model of coupled human-water systems, and to assess regional and global water security.  相似文献   

A study on groundwater recharge in the Anyanghe River alluvial fan,North China Plain,based on hydrochemistry,stable isotopes and tritium     

Huang  Xiangui  Ping  Jianhua  Leng  Wei  Yu  Yan  Zhang  Min  Zhu  Yaqiang 《Hydrogeology Journal》2021,29(6):2149-2170

Studies on groundwater recharge are essential for sustainable exploitation of groundwater resources, especially in areas of extensive groundwater exploitation such as the Anyanghe River alluvial fan (ARAF) in the North China Plain (NCP). However, the recharge sources and processes and the contribution of each recharge flow component remain unclear. This study used hydrochemistry, stable isotopes, and tritium to investigate sources and underlying processes of groundwater recharge, along with the steady flow Mixing Cell Model (MCMsf) to quantify the proportion of each source flow for the shallow confined groundwater system in the medial fan. The results showed that groundwater mainly originates from precipitation occurring on the eastern Taihang Mountain area with average elevation estimated at 700–1,000 m above sea level during the East Asia summer monsoon period since 1952. Recharge mechanisms are: (1) river water seepage for the unconfined aquifers of the proximal and medial fan; (2) lateral flow for the confined aquifers of the medial and distal fan; and (3) precipitation infiltration for the phreatic water system. The MCMsf simulation showed that the shallow confined groundwater system in the central zone of the medial fan mainly recharged by the lateral flow from the proximal fan, a constant and considerable recharge flow from the southwestern and southern hills, and river water seepage in the medial fan; the lateral recharge flow from the Zhanghe alluvial aquifer was insignificant by comparison. The results of this study can act as a valuable reference for sustainable groundwater management in the ARAF.

  相似文献   

嫩江流域新石器时代以来的环境考古(初步)研究     

冷程程  汤卓炜  张伟  介冬梅  王江永  刘旭  鲍彤 《第四纪研究》2019,39(1):48-58

嫩江流域孕育的昂昂溪文化是新石器时代中国北方"渔猎文化"的代表文化。文章对昂昂溪文化的典型代表遗址——洪河遗址附近3 m的自然沉积物剖面进行植硅体分析、粒度分析和烧失量测定,探讨了新石器时代以来嫩江流域人类活动的环境背景及昂昂溪"渔猎文化"走向衰亡的原因。结果表明,洪河剖面植硅体主要来自于禾本科植物,并以早熟禾亚科(C3植物)为主,剖面沉积物主要由嫩江冲积砂经风力吹扬、搬运、堆积而成。嫩江流域文化的空间分布和时间演替,在受到人类活动影响的同时,也与自然环境有密切的关系。在7024~3820 cal. a B.P.期间,嫩江流域气候温暖湿润,适宜人类生存繁衍,孕育了典型的昂昂溪"渔猎文化";在4000 cal. a B.P.左右,气候呈现逐渐变冷干的趋势,同时昂昂溪文化也逐渐衰落;3820~1000 cal. a B.P.期间,气候持续冷干,导致部分居民离开昂昂溪地区沿嫩江逐渐向更加温暖的下游迁移以寻找更为适宜的栖息地,昂昂溪文化逐渐被取代;1000 cal. a B.P.以来,人类活动频繁,土地沙漠化日趋严重。  相似文献   

Brief review on climate change and tropical peatlands     

Lee Yit Leng  Osumanu Haruna Ahmed  Mohamadu Boyie Jalloh 《地学前缘(英文版)》2019,10(2):373-380

In 2008, the very extensive tropical peats were estimated to be about 182 million ha spanning South America, Asia and Africa. About 20.3%(36.9 million ha) of this area exist in Asia. Peats are classified based on their degree of decomposition, namely Fibrists, Hemists, Saprists and Folists. This makes them different in characteristics. The activities of microorganisms vary in different types of peat due to, for example, the sapric layer of well humified peat can provide water and food to microorganisms during heat stress. In another scenario, deeper peat is older and typically has lower levels of labile carbon to provide substrate for microbes compared to surface peat. A complete understanding of the microbial communities in different layers of peat is essential as microorganisms play major roles in peat decomposition and are important to ecosystem processes. These peats are a very important global carbon(C)store or reserve and could severely impact climate change if not managed well. Peatlands can store as much as 40 to 90 Gt C. Mis-management of peats could severely impact the environment particularly the emission of carbon into the atmosphere. For instance, clearing of peatlands using fire has been reported to release an estimated 88 t C ha~(-1) to the atmosphere. There are several factors which influence the environmental consequences of tropical peat especially in relation to climate change. The main influences are:(i) changes in temperature,(ii) changes in precipitation or rainfall,(iii) changes in atmospheric composition, and(iv) fire and haze. This paper is a brief review on these four influences in relation to climate change. It is apparent from the brief review that there is a need for continued short and long-term research to better understand tropical peats and how they affect our climate. This will hopefully provide the basis for predicting better what could happen under various scenarios.  相似文献   

包头地区土壤环境质量地球化学初步评价   总被引：2，自引：0，他引：2  

冷福荣  曹金虎  丁天才 《内蒙古地质》1999,(2)

包头地区环境地球化学调查完成面积８００ｋｍ２,选定１６种微量元素的分级标准,采用综合污染指数和综合致贫指数对第二环境（地表）土壤的污染程度和致贫程度作出初步评价。并对全区土壤质量进行了分区,划分出三个一般过剩区,二个明显过剩区和二个明显不足区,评述了这七个质量区中微量元素的过剩程度和不足程度。同时对微量元素与农作物和地方病的关系进行初步调查分析,指出土壤质量下降已明显影响到农作物的生长和人体健康。文中还探讨土壤质量的影响因素,首先是自然景观因素,土壤中微量元素含量基本继承了原生环境中元素分布特征。其次是人类活动造成的环境污染是土壤质量下降的主因,应切实采取保护和治理环境的措施  相似文献   

气温偏高冬暖持续雨雪稀少旱情发展——1999年2月——     

孙冷 《气象》1999,25(5):62-63

2月份,全国仍持续偏暖,且偏暖幅度较大;全国及大部分省市区月平均气温为近40年来同期的最高值或次高值.雨雪依然偏少,全国及大部分省市区月降水量为近40年来同期的最小值或次小值,其中北方冬麦区大部滴水未降,旱情持续或发展.全国大部地区日照充足.暖干的气候条件对交通运输和旅游等行业十分有利,但却导致旱情发展和某些病虫害发生蔓延,对农业生产不利.  相似文献