Biomass and carbon storage of Gracilariopsis lemaneiformis （Rhodophyta） in Zhanshan Bay,Qingdao, China

Marine macroalgae can absorb carbon and play an important role in carbon sequestration. As an important economic macroalga, Gracilariopsis lemaneiformis has the potential to significantly affect carbon absorption and storage in wave-sheltered intertidal reef systems. However, detailed knowledge on seasonal biomass changes and carbon storage of G. lemaneiformis is lacking, especially in many small and scattered ecosystems. Considering the influence of human activities on wild distribution of G. lemaneiformis, the understanding of seasonal dynamics of an economically important species in nature is necessary. In this study, we first investigated seasonal variations in biomass, coverage area, and carbon storage during low tide from August 2011 to July 2012 in Zhanshan Bay, Qingdao, China. Furthermore, we estimated the carbon storage potential of wild G. lemaneiformis using light use efficiency(LUE). The results show that the standing biomass and coverage area changed significantly with season. However, seasonal variations in carbon content and water content were not obvious, with an average content of 35.1% and 83.64%, respectively. Moreover, carbon storage in individual months varied between 0.67 and 47.03 g C/m 2, and the value of carbon storage was the highest in August and June and the lowest in February. In Zhanshan Bay, LUE of G. lemaneiformis was only 0.23%. If it is increased to the theoretical maximum(5%–6%), the carbon storage will have an increase of at least 21 times compared with the current, which suggested that carbon storage of wild G. lemaneiformis had a high enhancement potential. The study will help to assess a potential role of G. lemaneiformis in reducing atmospheric CO2.     

基于土地利用类型的村级人口空间分布模拟——以湖北鹤峰县为例

在人口分布及其相关研究中,常常会遇到小尺度人口数据部分缺失的问题。本文以湖北省鹤峰县为例,在分析土地利用与人口分布关系的基础上,从全局与局部、线性回归与非线性回归考虑,基于土地利用类型,分别利用地理加权回归(GWR)方法、格网方法、BP神经网络方法对缺失数据的行政村人口数据进行模拟,并进行了多角度精度对比验证。研究结果表明:(1)各种土地利用类型中,耕地、林地、城镇村及工矿用地、交通用地是影响研究区村级人口分布的主要因素;(2)30个调查村中,3种方法模拟的人口总数误差小于3%,通过每个村的模拟值与实际值相比,BP神经网络方法能更好地模拟研究区村级人口的分布,格网方法次之,GWR方法最差;(3)研究区各村人口分布呈现较高的空间正相关性,各乡镇的人口密度在空间上并不独立,而是呈现紧密的集聚特征。     

黑潮入侵南海的强弱与太平洋年代际变化及厄尔尼诺-南方涛动现象的关系

在黑潮入侵南海强弱的问题上,到底是太平洋年代际变化(Pacific Decadal Oscillation,PDO)还是厄尔尼诺-南方涛动(El Nio-Southern Oscillation,ENSO)现象在起关键作用,目前还存在着较大争议。本文先以高盐水作为黑潮入侵强弱的示踪物,用120°E断面的高盐水数据和北赤道流分叉点(North Equator Current Bifurcation,NEC-Y)的南北变动进行相关分析,接着,进一步用学者所用的黑潮入侵指数(KI指数,Kuroshio intrusion index和NEC指数,North Equatorial Current index)与北赤道流分叉点南北变动进行相关分析。最后,用EMD(Empirical Mode Decomposition)方法和相关关系分析法分别分析了PDO指数、Nio3.4指数与北赤道流分叉点南北变动的关系并用NECP风场数据探讨其影响机制。结果表明:(1)通过对120°E断面的高盐水的KI指数、NEC指数与NEC-Y的相关分析,表明了北赤道流分叉点的南北变动能够很好地指代黑潮入侵南海的强弱;(2)通过PDO指数和Nio3.4指数与北赤道流分叉点的南北变动的相关性分析,发现PDO指数、Nio3.4指数与北赤道流分叉点的南北变动都具有较好的相关性,都在0.5水平。这些良好的相关性表明了PDO和ENSO对黑潮入侵南海的强弱都具有重要的影响;(3)当处于厄尔尼诺年(拉尼娜)时,赤道太平洋发生西(东)风异常,使得北赤道流分叉点偏北(南),使吕宋岛东侧的黑潮流速减弱(加强),黑潮入侵南海增强(减弱);当PDO处于暖(冷)阶段时,会加强热带太平洋的西(东)风异常,使得黑潮入侵南海增强(减弱)。     

Time of emergence of climate signals over China under the RCP4.5 scenario

The signal of climate change is emerging against a background of natural internal variability. The time of emergence (ToE) is an indicator of the magnitude of the climate change signal relative to this background variability and may be useful for climate impact assessments. In this work, we examined the ToE of surface air temperature and precipitation over China under a medium mitigation scenario Representative Concentration Pathway 4.5 based on 30 satisfactory global climate models that are chosen from the Coupled Model Intercomparison Project Phase 5. Major conclusions are: the earliest ToE of annual and seasonal temperature occurs in the eastern Qinghai-Tibetan Plateau between 2006 and 2012 for S/N?>?1.0 and between 2020 and 2030 for S/N?>?2.0, which is 10–20 years sooner than in Northeast China where the latest ToE appears in the country. Consistent with previous studies at the global scale, the median ToE for most of China occurs sooner in summer (2008–2020 for S/N?>?1.0 and 2020–2045 for S/N?>?2.0), while for Northeast and North China the median ToE occurs sooner in autumn (2015–2025 for S/N?>?1.0 and 2040–2050 for S/N?>?2.0). For the ToE of temperature, the inter-model uncertainty is at least 24 years in all five regions of concern and more than 85 years in some seasons, and the inter-model uncertainty in one season for which the earliest median ToE occurs is the smallest among the seasons. For precipitation, the early ToE occurs in the northeastern Qinghai-Tibetan Plateau for the annual mean, and seasonally it occurs first in winter in northern Northeast China and southwestern Northwest China and in winter and spring in the northeastern Qinghai-Tibetan Plateau. For southern China, the median ToE will not occur until 2090.     

Evaluation of EDI derived from the exponential evapotranspiration model for monitoring China’s surface drought

Drought has become the most severe natural disaster in many provinces of China. In this paper, evaporative drought index (EDI) has been used to monitor China’s surface dryness conditions based on the exponential evapotranspiration (ET) model and Hargreaves equation from JAXA-MODIS Insolation products, GEWEX, NCEP-2 and MODIS NDVI data. The exponential ET model based on the surface net radiation, vegetation index, mean air temperature and diurnal air temperature range (DTaR) has been developed to estimate surface ET of China and has been independently validated using ground-measured data collected from two sites (Arou and Miyun) in China, indicating that the bias varies from −5.96 to 5.02 W/m². The good agreement between daily estimated and ground-measured ET using ground observation data collected from all 22 sites further supports the validity of the exponential ET model for regional ET estimation. Moreover, EDI is closely correlated to the average soil moisture at 0–10 cm soil depth of the Yongning site with coefficient of determination of R ² = 0.52. The spatio-temporal patterns of monthly ET and EDI from April to September of 2004 over China are explored and the result indicates EDI is accordant with the precipitation by comparing the 15-day smoothed EDI with precipitation over six representative sites. The EDI based on the exponential ET model by integrating energy fluxes in response to soil moisture stress has demonstrated its validity for monitoring China’s surface drought events.     

2010年夏季北极冰情变化及大气环流场演变

利用美国冰雪中心(NSIDC)资料分析2010年夏季中国第4次北极科学考察期间北极海冰的冰情变化,并通过NCEP再分析资料对同时期的大气环流演变进行分析,发现6月与8月环流形势为偶极子正异常,加速了海冰的融化,其中2010年6月的海冰覆盖范围达到有历史记录以来的6月最低值;7月为低压控制,减缓了海冰覆盖范围的进一步减少...     

多粒度的人群移动模拟通用模型及其应用

人群的移动模拟应用广泛,但为不同时空尺度模拟需求开发不同的模拟系统十分困难和繁琐。该文设计了一种人群的空间移动模型(GMPM),GMPM具有多粒度特性,可应用于不同的领域,满足不同空间尺度、时间尺度的人群移动模拟需求;同时,GMPM又是一种通用开发模型原型,基于GMPM可以构造针对不同应用领域的人群空间移动模拟模型。最后,介绍了不同时空尺度人群移动模拟应用案例。     

Early warning for geo-hazards based on the weather condition in China

According to national early warning practice for geo-hazards from 2003 .to 2005, it is systematically concluded that the basic characteristics of geo-hazards, early warning method and forecast result based on the geological maps of China in a scale 1：6 000 000. With the contrast of different characters between sustained rainfall and typhoon rainfall inducing geo-hazards, the disaster reduction result and some problems are preliminarily analyzed. Some basic recognition is that early warning to geo-hazards is feasible, national scale forecast is only to call attention, but can＇ t immediately be used to disaster reduction decision-making. And, the future direction is to build a united disaster reduction framework of early warning system including national, provincial and county levels based on weather factors in different scale of area.     

印度西部洋陆过渡区结构特征及构造演化

印度西部洋陆过渡区位于上印度扇,处于印度板块、阿拉伯板块和欧亚板块交汇处,周缘发育多种板块边界类型,构造特征复杂.前人对该区域的构造性质及演化的研究较少,其内部一级构造的地壳性质认识存在争议.本文在对地震资料构造解析的基础上,分析了印度扇近海盆地、默里脊系统和拉克西米山脊的断裂样式、断裂组合以及盆地结构特征,揭示印度西缘的洋陆过渡区为发育向海倾斜反射层(SDRs)和下地壳高速体(HVZ)的火山型被动陆缘.其中,印度扇近海盆地的断层多构成地堑、半地堑和地垒组合,地壳性质为减薄陆壳;默里脊系统表现为右行张扭性质,以小默里脊为界,以西为正在低速扩张的洋壳基底,以东为减薄的陆壳;拉克西米山脊地壳性质则为减薄的陆壳.印度西缘的洋陆过渡区的形成与白垩纪以来马达加斯加板块、塞舌尔微板块和印度板块之间的多期裂解事件,以及多个热点导致的岩浆事件有关.此外,运用2DMove软件进行了平衡剖面恢复,揭示了印度扇在新生代以来经历了古-始新世初始伸展断陷期、渐新世-早中新世稳定沉积期、中-晚中新世张扭断陷期和上新世以来的热沉降期4个构造演化阶段.     

Meso‐Cenozoic Evolution of Earth Surface System under the East Asian Tectonic Superconvergence

The East Asian geological setting has a long duration related to the superconvergence of the Paleo‐Asian, Tethyan and Paleo‐Pacific tectonic domains. The Triassic Indosinian Movement contributed to an unified passive continental margin in East Asia. The later ophiolites and I‐type granites associated with subduction of the Paleo‐Pacific Plate in the Late Triassic, suggest a transition from passive to active continental margins. With the presence of the ongoing westward migration of the Paleo‐Pacific Subduction Zone, the sinistral transpressional stress field could play an important role in the intraplate deformation in East Asia during the Late Triassic to Middle Jurassic, being characterized by the transition from the E‐W‐trending structural system controlled by the Tethys and Paleo‐Asian oceans to the NE‐trending structural system caused by the Paleo‐Pacific Ocean subduction. The continuously westward migration of the subduction zones resulted in the transpressional stress field in East Asia marked by the emergence of the Eastern North China Plateau and the formation of the Andean‐type active continental margin from late Late Jurassic to Early Cretaceous (160‐135 Ma), accompanied by the development of a small amount of adakites. In the Late Cretaceous (135‐90 Ma), due to the eastward retreat of the Paleo‐Pacific Subduction Zone, the regional stress field was replaced from sinistral transpression to transtension. Since a large amount of late‐stage adakites and metamorphic core complexes developed, the Andean‐type active continental margin was destroyed and the Eastern North China Plateau started to collapse. In the Late Cretaceous, the extension in East Asia gradually decreased the eastward retreat of the Paleo‐Pacific subduction zones. Futhermore, a significant topographic inversion had taken place during the Cenozoic that resulted from a rapid uplift of the Tibet Plateau resulting from the India‐Eurasian collision and the formation of the Bohai Bay Basin and other basins in the East Asian continental margin. The inversion caused a remarkable eastward migration of deformation, basin formation and magmatism. Meanwhile, the basins that mainly developed in the Paleogene resulted in a three‐step topography which typically appears to drop eastward in altitude. In the Neogene, the basins underwent a rapid subsidence in some depressions after basin‐controlled faulting, as well as the intracontinental extensional events in East Asia, and are likely to be a contribution to the uplift of the Tibetan Plateau.