欧亚大陆土壤焓异常持续性的时空变化特征

土壤焓作为一种综合考虑地表状况(如土壤湿度、土壤温度等)的特殊陆面因子,可以直接从能量角度反映陆地下垫面的热力状况,故探讨土壤焓异常持续性的相关特征,有助于加深理解地表热力异常对气候的影响。本研究基于陆面过程模式CLM4.0模拟的土壤温度、土壤液态水和土壤固态水及土壤物质类型(IGBP地表属性),分别计算了欧亚大陆冬季和夏季土壤干物质焓、土壤液态水焓和土壤固态水焓及土壤焓(前三者之和);由于土壤温度和土壤固、液态水含量的差异,浅层土壤焓及其三个组元表现出明显的区域性和季节性特征;欧亚大陆冬季土壤焓异常持续性总体较夏季强,尤其是中高纬地区;另外,土壤干物质焓、液态水焓的纬度和季节性差异也体现在对近地面大气的热力强迫上,具体表现为土壤干物质焓、液态水焓分别与感热、潜热密切相关。本研究通过较为细致地分析土壤焓异常持续性的时空变化特征,为进一步开展下垫面热力异常(以土壤焓表征)的气候效应提供了重要的信息参考。     

我国东北及邻近地区年平均气温异常及其对北半球气候变暖和欧亚雪盖面积的响应

根据我国东北及邻近地区201个常规气象台站的年平均气温资料,利用EOF和分段线性拟合等方法分析了该地区气温异常的年代际特征及其对北半球气温和欧亚雪盖面积的响应.结果表明:我国东北及邻近地区年平均气温异常主要有全区一致型和南北反向型两种.近50 a来气温总体呈单调上升趋势,尤其是1990年代后期增温趋势更加明显,时间上东部早于西部.结合降水,1980年代起东北北部由冷干向暖湿转变,而华北区则由暖湿向暖干转变.东北北部升温单调、剧烈、显著,南部在1968和1985年曾两次发生突变,经历过1970-1980年代初的低温后增温趋势更加剧烈,其增温率几乎是第一次突变前的两倍.分析认为,我国东北及邻近地区大范围整体变暖与北半球平均气温的升高相一致;东北部气温的年际变化还受到欧亚雪盖面积的影响.     

欧亚和我国东北冬春季积雪对东北夏季气温的影响

根据我国东北及邻近地区123个气象站的逐日气温和积雪深度资料,欧亚大陆积雪面积以及NCEP/NCAR全球再分析月平均500hPa高度场资料,通过相关、合成分析等方法,研究了东北夏季气温异常对欧亚和我国东北冬春季积雪的响应,并从大气环流的角度出发分析了欧亚和我国东北冬春季积雪对东北夏季气温异常形成的影响机制.结果表明:东北地区夏季气温与欧亚大陆春季积雪面积以及东北冬季累积雪深的异常存在明显的关系.欧亚春季积雪面积的扩大与维持有利于8月我国东北上空500hPa位势高度的偏低,环流上表现出西欧与我国东北地区槽加深,泰梅尔阻塞高压加强的特征.由于欧亚中高纬上空的环流经向度加大,槽后脊前的西北气流加强,诱导冷空气南下,从而造成东北全区8月气温一致偏低;东北冬季累积雪深减少则有利于6月东北全区、7月东北西南部上空的位势高度偏低(负距平),造成相关区域气温偏低.研究结果对于提高东北夏季气温的短期气候预测水平具有重要意义.     

Northern Eurasia earth science partnership initiative (NEESPI), science plan overview

Northern Eurasia Earth System Partnership Initiative, NEESPI, was established to address the global change processes associated with and/or originated within Northern Eurasia as well as to study the major socially-important processes within the region. NEESPI began as a US–Russian initiative but has quickly broadened into a fully international program. Scientists from 11 countries participated in preparing the NEESPI Science Plan. Current version of the Science Plan was released for public review on the World Wide Web in summer 2004 and finalized in December 2004. This paper provides an Overview of the Plan and is based, mainly, on its Executive Summary. The Overview describes the Plan's science themes and key science questions, provides a justification of the urgency studying Northern Eurasia from the global change prospective, and outlines research strategy and tools to address NEESPI science questions, as well as projected deliverables of the Initiative.     

Geographical extremes in the glacial history of northern Eurasia: post-QUEEN considerations

This paper summarizes the principal results produced by the European Science Foundation's programme, Quaternary Environment of the Eurasian North (QUEEN). These results concern the distribution of late Quaternary glaciers of different ages across northern Eurasia. The pattern of glaciation is compared with the west–east climatic gradient of the continent. Of particular significance is the coincidence of the Late Weichselian ice margin with the modern 30°C difference between the July and January mean air temperatures. The difference between west and east in the annual amplitude of air temperature did not decrease during the Pleniglacial. The asymmetry of the glacial history suggests a progressive aridification of the Eurasian North, with the result that by marine isotope stage 2 significant ice volumes could only accumulate along the Atlantic seaboard. The different climatic signals of thermochrons and cryochrons of the extreme west and east of the continent are discussed. The growth of continentality eastwards restrains the applicability of pollen proxies for climatic reconstructions.     

Paleomagnetism of the Late Cretaceous ignimbrite from the Okhotsk-Chukotka Volcanic Belt,Kolyma-Omolon Composite Terrane: Tectonic implications

New Late Cretaceous paleomagnetic results from the Okhotsk-Chukotka Volcanic Belt in the Kolyma-Omolon Composite Terrane yield stable and consistent remanent directions. The Late Cretaceous (86–81 Ma) ignimbrites from the Kholchan and Ola suites were sampled at 19 sites in the Magadan area (60.4° N, 151.0° E). We isolated the characteristic paleomagnetic directions from 16 sampled sites using an alternating field demagnetization procedure. The primary nature of these directions is ascertained by dual polarities and positive fold tests. A tilt-corrected mean direction (D = 42.8°, I = 84.7°, k = 46.0, α₉₅ = 10.0°) yields a paleomagnetic pole of 66.7° N, 168.5° E (A₉₅ = 18.8°) which appears almost identical to the 90–67 Ma pole reported from the Lake El’gygytgyn area of the Okhotsk-Chukotka Volcanic Belt (Chukotka Terrane). This consistency suggests that the Kolyma-Omolon Composite Terrane and Chukotka Terrane has acted as a single tectonic unit since 80 Ma without any significant internal deformation. Accordingly, we calculate a combined 80 Ma characteristic paleomagnetic pole (Long. = 164.7° E, Lat. = 68.0°, A₉₅ = 10.9°, N = 12) for the Kolyma-Omolon-Chukotka Block which falls 16.5–17.5° south of the same age poles from Europe and East Asia. We ascribe this discrepancy in pole positions to tectonic activity in the area and infer a southward displacement of 1640 ± 1380 km for the Kolyma-Omolon-Chukotka Block with respect to the North American and Eurasian blocks since 80 Ma; more than 260 km of it is attributed to tectonic displacement in the Arctic Ocean due to the opening of the Canadian Basin.     

Post-Soviet urban renewal and its discontents: gentrification by demolition in Baku

ABSTRACT

Gentrification is being increasingly discussed as a driver of urban change globally, including in the former Soviet Union. However, the translation of the gentrification phenomenon into post-Soviet cities like Baku remains poorly understood. This article explores how a particular form of state-led “gentrification by demolition” is unfolding in Baku. We assert the ongoing relevance of using the framework of gentrification to analyze the processes. We go on to use the case of the recently demolished Sovetsky district to carefully expand the geography of the gentrification discourse. We argue that Baku’s own “landscape of gentrification” is shaped by anumber of preconditions. It bears the marks of the legacy of post-socialist cities. However, it more resembles muscular state-led “gentrification by demolition” that is characteristic of Chinese cities. It also echoes Soviet city-building legacies in its use of spectacle and “grand gesture” to legitimize and buy support for gentrification policies.     

1900年以来全球地震活动的初步分析

20世纪50年代和60年代，是全球地震矩的大释放阶段。从60－80年代地震矩释放速率呈下降的趋势。90年代后，地震矩释放速率有所回升。从50－80年代，中国大陆及东半球的地震矩释放速率有明显的下降趋势。一次9级左右地震的成丛是20世纪地震活动的明显特点。     

Relict back-arc basins of Eurasia and their hydrocarbon potentials

Abstract Large petroliferous basins in the continental interior are characterized by very thick sedimentary sequences. It is suggested that these are not intracratonic basins, but areas underlain by oceanic crust. These include the Western Siberian, Pre-Caspian, South Caspian, North and South Kara Basins of the Commonwealth of Independent States, and Tarim, junggar and Qaidam Basins of China. The relict ocean basins are distinguished by their basement topography, by their magnetic signatures and by their elevated Moho. Their sedimentary history is distinguished by an abrupt subsidence, followed by isostastic subsidence under sedimentary load. Two circumstances have contributed to the genesis of giant hydrocarbon deposits in these basins: (1) the geochemical environment in those basins was at one time oxygen-deficient as they evolved from the open marine, through restricted marine to become inland alluvial basins; and (2) the sedimentary in-fill provide thick reservoir beds. Oil has accumulated in older structures, folds, faults, unconformities etc. on the margin of the basins, trapping early migrated hydrocarbons.