Precipitation cycles in the middle and lower reaches of the Yellow River （1736-2000）

Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.     

1996-2005年壮族传统民居的期刊文献分析

通过对中国期刊全文数据库检索,选择在1996-2005十年间,有关壮族传统民居——干栏式建筑的期刊文献,从论文发表的时间及刊物、资助的课题、作者、理论与案例、学科角度等方面对文章进行了归类、分析,并对研究的现状做了一些评述,得出了当前研究角度广泛但是深度不够、课题资助的力度有待加强、开始关注对传统民居及其文化的保护、以旅游开发进行民居保护成为研究的新方向等结论。     

Susceptibility assessment of earthquake-triggered landslides in El Salvador using logistic regression

This work has evaluated the probability of earthquake-triggered landslide occurrence in the whole of El Salvador, with a Geographic Information System (GIS) and a logistic regression model. Slope gradient, elevation, aspect, mean annual precipitation, lithology, land use, and terrain roughness are the predictor variables used to determine the dependent variable of occurrence or non-occurrence of landslides within an individual grid cell. The results illustrate the importance of terrain roughness and soil type as key factors within the model — using only these two variables the analysis returned a significance level of 89.4%. The results obtained from the model within the GIS were then used to produce a map of relative landslide susceptibility.     

Precipitation cycles in the middle and lower reaches of the Yellow River (1736?2000)

Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736?2000 recon-structed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipita-tion changes, are explored. The results show that: the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2?4a, quasi-22a and 70?80a. The 2?4a cycle is linked with El Ni?o events, and the precipitation is lower than normal year in the occurrence of the El Ni?o year or the next year; for the quasi-22a and the 70?80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation (PDO) coincide with the two cycle signals. However, on a 70?80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong (weak) solar activity is generally correlated to the dry (wet) periods; after 1830, the solar activity changes to 80?100a quasi-century long oscillation, and the adjusting action to the precipitation is be-coming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70?80a time scale.     

不同强度El Nino的衰减过程.Ⅰ,强El Nino的衰减过程

将1951～2004年期间的12次El Nino事件分为强、中等、较弱和弱4类,结果发现,强和较弱El Nino衰减进入La Nina,但是中等和弱El Nino衰减进入平常态.因此,El Nino的衰减结果与自身强度之间存在密切的非线性关系.进一步的研究表明,负异常信号自西太平洋向中东太平洋的东传主导了强El Nino事件向La Nina的转变过程,其具体动力过程类似于西太平洋振子理论.热带西北太平洋（WNP）大气异常反气旋在强El Nino位相转变中起核心作用,它的维持和缓慢东移是赤道东风异常维持和发展的原因,而后者通过激发Kelvin波导致了ENSO从El Nino向La Nina的转变.     

基于聚落地名记录的过去300年吉林省土地开垦过程

聚落作为一种土地利用类型,是人类活动与自然环境之间相互作用的综合反映。新开垦区的聚落建立与农业土地开垦相辅相成,聚落格局演变可反映出土地开垦的过程。聚落地名,记录人类移居到新开垦区域时的直观状况,对于认识土地开发过程和恢复土地利用/覆被变化的历史进程有着重要的价值。本文根据地名志资料,将聚落地名依据不同的土地开垦类型进行划分,提出了土地开垦-聚落地名的分类方法,在此基础上辨识出土地开垦-聚落类型,即官垦聚落和民垦聚落,其中民垦聚落又可分为自发移民聚落和政府招垦聚落,并得到各类型聚落近300年来的时空格局演变过程,为认识吉林省土地利用/覆被变化提供依据,也为利用聚落地名进行土地开垦格局重建提供尝试。     

过去2000年中国气候变化研究

总结了中国科学院地理科学与资源研究所在过去2000年中国气候变化研究方面的主要进展,并对未来研究动向进行了展望。在过去10余年中,中科院地理资源所的历史气候变化研究在已有基础上,面向国际本领域研究的前缘科学问题,开展了大量研究工作,在代用资料的收集、整理与数据库建设,温度与降水变化重建以及气候变化的时空特征分析等方面取得了许多新成果。未来不但需要进一步利用历史文献、树轮等气候变化重建手段,加强高分辨率的气候变化重建工作,加密气候变化代用资料的空间覆盖度,并结合历史气候模拟等手段,深入开展气候变化动力学机制研究;而且还需要进一步利用地理资源所在本领域已积累的研究优势,开展历史时期的气候变化与人类相互作用等方面的研究。     

近500年来长江上游亚热带山地中低山植被的演替

从人口分布变迁入手探讨植被变迁,发现距今500年以前,长江上游亚热带山地海拔3000~1500m的中低山地区多是乔木林为主而间与草甸混交景观,而非现在的以草甸、灌草坡为主的景观。人类主要居住在海拔1500m以下的平坝、台地和丘陵地区,人类活动对海拔1500m以上的山地地区影响甚小。现代地理学界静态描述的长江上游地区海拔1500~3000m的中低山湿地草坡带,在500多年前仍多是以冷杉、云杉为主的针阔叶林与草甸混交景观。近500年来人类垦殖、商业砍伐、皇木采办等活动是造成这种变化的主要原因。皇木采办、商业采办影响了长江上游中低山的森林资源的品质,主要对高大的楠杉的砍伐,较明显地影响了森林的郁闭度,但并不给森林资源带来不可回归的影响。人类垦殖活动,特别是固定的农耕活动,大量砍挖树根,使森林资源的自我恢复失去了可能。气候变化的影响可能在其中,一时还难以区分,需继续关注。     

The influence of El Niño-Southern Oscillation (ENSO) cycles on wave-driven sea-floor sediment mobility along the central California continental margin

Ocean surface waves are the dominant temporally and spatially variable process influencing sea floor sediment resuspension along most continental shelves. Wave-induced sediment mobility on the continental shelf and upper continental slope off central California for different phases of El Niño-Southern Oscillation (ENSO) events was modeled using monthly statistics derived from more than 14 years of concurrent hourly oceanographic and meteorologic data as boundary input for the Delft SWAN wave model, gridded sea floor grain-size data from the usSEABED database, and regional bathymetry. Differences as small as 0.5 m in wave height, 1 s in wave period, and 10° in wave direction, in conjunction with the spatially heterogeneous unconsolidated sea-floor sedimentary cover, result in significant changes in the predicted mobility of continental shelf surficial sediment in the study area. El Niño events result in more frequent mobilization on the inner shelf in the summer and winter than during La Niña events and on the outer shelf and upper slope in the winter months, while La Niña events result in more frequent mobilization on the mid-shelf during spring and summer months than during El Niño events. The timing and patterns of seabed mobility are addressed in context of geologic and biologic processes. By understanding the spatial and temporal variability in the disturbance of the sea floor, scientists can better interpret sedimentary patterns and ecosystem structure, while providing managers and planners an understanding of natural impacts when considering the permitting of offshore activities that disturb the sea floor such as trawling, dredging, and the emplacement of sea-floor engineering structures.     

地学时间单位Ma和Myr及其派生单位用法的探讨

针对夏明生先生认为“Ma”及其派生单位(如“m/Ma”和“℃/Ma”)在地学期刊中属错误用法的观点,查阅了国家标准GB 3100-93和国际地学期刊有关规定。进而提出“Ma”和“Myr”均可表示“100万年”的观点,并指出这两个单位在国际期刊用法中的区别,即“Ma”用于表示某一地质事件距今的绝对年代(absolute dates),而“Myr”用于表示某一地质事件的延续时间或时间间隔(duration或interval)。另外,还提出了Ma”和“Myr”的派生单位供大家讨论。