基于随机森林模型的东北地区收缩城市分布格局及影响因素研究

基于2005-2009年、2010-2014年、2015-2019年和2005-2019年人口变化数据,判定东北地区收缩城市,分析其空间分布格局,并对比运用多元线性回归方法和随机森林回归方法探索东北地区收缩城市形成的影响因素及其影响作用.结果 表明:①空间上,东北地区的收缩城市主要分布在以长白山、三江平原、小兴安岭和大...     

气候变化对东北大西洋渔获物组成、多样性和营养级的影响

东北大西洋是世界上重要的捕捞海域,气候变化对该海域捕捞产生了重要的影响。本文基于联合国粮农组织所提供的1982-2016年东北大西洋渔获产量数据,对该海域渔获物组成、多样性、平均营养级及主成分变化特征进行时间序列上的分析,并结合东北大西洋海域气候、环境因子,应用广义可加模型探究渔获物组成与气候变化之间的关系。结果显示:渔获物多样性的变化总体上呈下降趋势,2002-2010年间处于较低水平;平均营养级在2002年之前呈平缓下降的趋势,2002年之后开始波动上升,相关性分析表明这两个指标与海域环境因子的变化较为相关。对渔获物组成进行主成分分析显示,第一主成份变化的方差解释率达到35.3%,且与海域气候、环境因素有较高的相关性,第一主成分变化能够较好地表征气候影响下渔获物组成变化的情况。广义可加模型分析结果显示,渔获物组成变化的影响因素按解释率由高到低分别为:海表温度、海平面高度、盐度、海冰和北大西洋涛动指数。该研究有助于认识气候变化对海洋渔业资源及其结构组成的影响。     

印度洋通道及其对中国地缘环境影响

印度洋通道是中国获取能源和其他资源、出口工业产品并同南亚、西亚、非洲和欧洲国家交流合作的生命线。随着中美关系和中国周边地缘态势的深刻变化,中国需要积极谋划逐渐降低对传统的南海—马六甲海峡通道的依赖,建设新的印度洋通道,从而降低自身的地缘环境风险,并由此优化国内经济发展布局,推动西南沿边地区进一步开发与开放,并提升中国同印度洋沿岸国家和地区的交流与合作水平。本研究从通道的定义和特征出发,梳理了现有及潜在的印度洋通道,比较分析了各条通道的战略意义、前景及地缘环境影响,从而为中国的印度洋战略构建和“一带一路”倡议推进提供新的视角和见解。     

基于“永盛轮”航线冰情分析的北极东北航线通航性研究

海冰冰情是开发、利用北极航道的关键信息,研究利用2006—2015年北极地区逐日海冰密集度数据,根据2013年"永盛轮"首航北极东北航道时所经航线为例,提取了航线冰情要素,包括航线通航窗口、逐日海冰密集度时空分布以及海冰密集度月标准差等,对航线通航条件进行了研究。根据航线冰情要素获得了十年间航线通航窗口的基本情况,十年间航线所经水域的大体通航情况和主要冰障位置,7—10月份航线所经水域海冰密集度的变化动态。通过对航线冰情要素的分析,得出影响航线的两个关键海域,并分析了"永盛轮"航线与关键水域航线通航窗口的变化趋势。     

Sedimentary charateristics and hydrocarbon accumulation in Northeast Sichuan basin

Northeast Sichuan basin is a Mesozoic-Cenozoic basin in the northern margin of the Yangtze plate which has a complex tectonic background and hydrocarbon accumulation history. By means of the analysis method of wave processes, major cycles of sedimentary wave process in this basin have been studied. The results show that there are five-order cycles corresponding to 760, 220, 100, 35 and 20 Ma respectively, two first-order sedimentary cycles (220 Ma) and four secondorder sedimentary cycles (100 Ma). The authors find that the second-order sedimentary cycles are well matched with reservoir formation cycles through studying the relationship between second-order sedimentary cycles and reservoir formation cycles, and divide three reservoir formation cycles in this basin. __________ Translated from Journal of Jilin University (Earth Science Edition), 2007, 37(3): 513–518 [译自: 吉林大学学报(地球科学版)]     

Heat flow and lithospheric thermal regime in the Northeast German Basin

New values of surface heat flow are reported for 13 deep borehole locations in the Northeast German Basin (NEGB) ranging from 68 to 91 mW m^− 2 with a mean of 77 ± 3 mW m^− 2. The values are derived from continuous temperature logs, measured thermal conductivity, and log-derived radiogenic heat production. The heat-flow values are supposed free of effects from surface palaeoclimatic temperature variations, from regional as well as local fluid flow and from thermal refraction in the vicinity of salt structures and thus represent unperturbed crustal heat flow. Two-D numerical lithospheric thermal models are developed for a 500 km section along the DEKORP-BASIN 9601 deep seismic line across the basin with a north-eastward extension across the Tornquist Zone. A detailed conceptual model of crustal structure and composition, thermal conductivity, and heat production distribution is developed. Different boundary conditions for the thickness of thermal lithosphere were used to fit surface heat flow. The best fit is achieved with a thickness of thermal lithosphere of about 75 km beneath the NEGB. This estimate is corroborated by seismological studies and somewhat less than typical for stabilized Phanerozoic lithosphere. Modelled Moho temperatures in the basin are about 800 °C; heat flow from the mantle is about 35 to 40 mW m^− 2. In the southernmost part of the section, beneath the Harz Mountains, higher Moho temperatures up to 900 to 1000 °C are shown. While the relatively high level of surface heat flow in the NEGB obviously is of longer wave length and related to lithosphere thickness, changes in crustal structure and composition are responsible for short-wave-length anomalies.     

1979-2013年东亚中纬度春、夏温带气旋活动特征及其与东北地区同期降水的联系

利用江苏近10 a（2005-2014年）暖季（5-9月）69站逐时降水资料,详细分析了短时强降水的空间分布、年际变化、季节内演变以及日变化特征。分析结果表明：短时强降水空间分布不均,整体上北部比南部活跃,最活跃区均位于沿淮西部,高强度短时强降水多发生在淮北东部,且空间分布集中。近10 a来江苏短时强降水整体呈减少趋势,主要表现为北部地区减少最为显著。短时强降水季节内分布不均匀,以7月最为活跃,高强度短时强降水在8月最为频繁;其逐候分布显示,梅期短时强降水骤增,于7月第2候达到峰值,盛夏期间高强度短时强降水增多,8月第3候达到峰值。江苏短时强降水的日变化整体呈双峰结构,主峰和次峰分别出现在傍晚17时（北京时间,下同）和清晨07时,高强度短时强降水多发于午后;短时强降水日变化存在季节内演变的阶段性特征和地域性差异,其中梅期和盛夏两个高发阶段均呈单峰结构,但梅期峰值出现在清晨,盛夏阶段峰值则出现在傍晚;由南向北,日变化特征由单峰向双峰、多峰演变,在淮河以南地区日峰值大多出现在午后至傍晚,而淮河以北地区多出现在夜间至清晨。     

东北亚经济协作与图们江流域发展计划

在东北亚区域发展方向论述了经济快速增长，资源转移和区域贸易格局的特点，随着后分析了图们江地区开发的国际环境以及图们江发展计划，指出图们江开发的几种可能选择和图们江与东北亚经济协作前景，特别提出加强国与国之间的贸易具有重要意义。     

The dynamic monitoring of corn planting area distribution in response to climate change from 2001 to 2010: a case study of Northeast China

Climate change has effects on crop distribution and production due to altering precipitation and temperature patterns. Northeast China is one of the most sensitive areas affected by climate change. In this study, MODIS09A1 data from MODerate resolution Imaging Spectroradiometer incorporated with phenology data from 21 agro-meteorological stations were used to monitor the dynamic change of corn distribution in response to climate change in the Northeast China for the decade of 2001 and 2010. Corn area estimates and statistics had the same change trend from 2001 to 2010 showing an annual increase. Furthermore, in order to analyse the gravity centre variations of the corn distribution, regions were chosen with corn planting areas of more than 500 km². Results showed that the main corn planting area had a trend to move towards high latitude and high longitude in response to climate change. It moved towards north about .58 degrees and east about .21 degrees between 2001 and 2010. The analysis of temperature and precipitation patterns revealed the same trend as the corn planting area. However, the corn area change was more sensitive to temperature than precipitation in Northeast China.     

Evolution of permafrost in Northeast China since the Late Pleistocene

In Northeast China, permafrost advanced and retreated several times under the influences of fluctuating paleo-climates and paleo-environments since the Late Pleistocene. During the last 60 years, many new data were obtained and studies were conducted on the evolution of permafrost in Northeast China, but so far no systematic summary and review have been made. Based on sedimentary sequences, remains of past permafrost, paleo-flora and-fauna records, and dating data, permafrost evolution since the Late Pleistocene has been analyzed and reconstructed in this paper. Paleo-temperatures reconstructed from the remains of past permafrost and those from paleo-flora and-fauna are compared, and thus the southern limit of permafrost(SLP) in each climate period is inferred by the relationship of the permafrost distribution and the mean annual air/ground temperatures(MAAT/MAGT). Thus, the evolutionary history of permafrost is here divided into five stages:(1) the Late Pleistocene(Last Glaciation, or LG)(65 to 10–8.5 ka), the Last Glaciation Maximum(LGM, 21–13 ka) in particular, the coldest period in the latest history with a cooling of about 6~10 ?C, characterized by extensive occurrences of glaciation, flourishing Mammathas-Coelodonta Faunal Complex(MCFC), widespread aeolian deposits, and significant sea level lowering, and permafrost greatly expanded southwards almost to the coastal plains(37?N–41?N);(2) the Holocene Megathermal Period(HMP, 8.5–7.0 to 4.0–3.0 ka), 3~5 ?C warmer than today, permafrost retreated to about 52°N;(3) the Late Holocene Cold Period(Neoglaciation)(4.0–3.0 to 1.0–0.5 ka), a cooling of 1~3 ?C, some earlier thawed permafrost was refrozen or attached, and the SLP invaded southwards to 46?N;(4) the Little Ice Age(LIA, 500 to 100–150 a), the latest cold period with significant permafrost expansion; and(5) climate warming since the last century, during which Northeast China has undergone extensive permafrost degradation. The frequent and substantial expansions and retreats of permafrost have greatly impacted cold-region environments in Northeast China. North of the SLP during the HMP, or in the present continuous permafrost zone, the existing permafrost was largely formed during the LG and was later overlapped by the permafrost formed in the Neoglaciation. To the south, it was formed in the Neoglaciation. However, many aspects of permafrost evolution still await further investigations, such as data integration, numerical reconstruction, and merging of Chinese permafrost history with those of bordering regions as well as collaboration with related disciplines. Of these, studieson the evolution and degradation of permafrost during the past 150 years and its hydrological, ecological, and environmental impacts should be prioritized.