A Simple Graphical Technique for Conditional Long Range Forecasting of Below-Average Rainfall Periods in the Tuvalu Islands, Western Pacific

For the Tuvalu Island group in the western Pacific, a simple graphical method is proposed as a means of forecasting whether rainfall totals for the next 1, 2,…,6 months will be below average. The method is based on scatter plots where the points are color-coded as above- or below-average rainfall, with the plot axes being lag-1 and lag-2 NINO4 sea surface temperatures. Within the scatter plots there are reasonably clear data fields with higher frequencies of below-average rainfalls associated with cooler precursor NINO4 temperatures. These data fields are defined by subjectively emplaced separation lines which bifurcate the scatter plots into “predictable” and “unpredictable” fields. If two precursor NINO4 temperature values define a point located in a predictable field then a warning would be issued for below-average rainfall over the next n-month period, depending on the time scale of the scatter plot. A long rainfall record at Funafuti in Tuvalu indicates that success in predictable-field forecasting of below-average rainfalls would range between 68% for 1-month rainfall totals and 89% for 6-month totals. The forecasting success derives from persistence of cooler NINO4 sea surface temperatures which are associated with lower rainfalls in Tuvalu. However, many dry periods are also located in the unpredictable field and cannot be forecast by this method.     

Linking hurricane landfalls,precipitation variability,fires, and vegetation response over the past millennium from analysis of coastal lagoon sediments,southwestern Dominican Republic

We reconstructed the late-Holocene environmental history of a coastal lagoon in semi-arid southwestern Hispaniola through multiproxy analysis of a sediment core, including pollen, macroscopic and microscopic charcoal, loss-on-ignition analysis (LOI), stable isotope analysis, bulk density, and magnetic susceptibility. Four chronological accelerator mass spectrometry radiocarbon dates indicated that our core represents the past ~1000 years. We interpreted ten hurricanes events over the past millennium from high-resolution geological proxies, LOI data, and ostracod valve stable oxygen isotope data, thus producing the first long record of hurricanes from the Dominican Republic. Geological proxies indicated a high-energy event abruptly changed the ecosystem state of our core site from a shallow mangrove wetland to a lacustrine environment ~330 cal yr BP. We interpret the driver of that event to be the landfall of a strong hurricane that initiated lowland flooding, mangrove mortality, and subsequent peat collapse at the core site. Pollen data indicated that during the relatively moist Medieval Warm Period (MWP), hurricanes led to temporary declines in tropical dry forest taxa that recovered within several decades following disturbance. By comparison, during the relatively arid Little Ice Age (LIA), when precipitation was highly variable in the circum-Caribbean, closely spaced hurricanes seemed to delay forest recovery. Sedimentary charcoal concentrations revealed increased fire activity after inferred hurricane landfalls in the MWP, providing evidence of a link between enhanced biomass and fuel availability during moister periods and burning in recently disturbed dry forests and scrub of our semi-arid study region. Our interpretations of increased aridity and precipitation variability, indicated by alternating thin layers of microbial mats with evaporite layers, along with more frequent hurricanes from ~330 cal yr BP to present, generally agree with other sedimentary records from the circum-Caribbean, and may be linked to a more southerly position of the Intertropical Convergence Zone during the LIA.     

A climatological study of the effect of sea-surface temperature on North Atlantic hurricane intensification

The climatic influence of sea-surface temperature (SST) on intensification is examined for North Atlantic hurricanes by averaging hourly intensity increases from best-track data over the period 1986–2013 in 4° by 4° latitude–longitude grid cells. Independent monthly SST data over the same period are averaged in the same cells. After removing cells with cold water or fast moving hurricanes, the SST effect on intensification, at the climate scale, is quantified by regressing intensification onto SST while controlling for average intensity. The regression is performed using a generalized linear model from a gamma family and a logarithmic link function. The model shows a statistically significant relationship, with higher intensification values associated with higher SST values. On average, mean intensification increases by 16% [(9,?20)% uncertainty interval] for every 1 °C increase in mean SST. A clustered region where the model underpredicts intensification is noted over the southeastern Caribbean Sea, perhaps related to the fresh water plume from the Orinoco River.     

Managing Ontong Java: Social institutions for production and governance of atoll resources in Solomon Islands

This paper explores the changing nature of social institutions and organizations for resource management on Ontong Java and their central role in maintaining livelihoods. Using detailed field data for three time periods, 1970–72, 1986 and 2006–07, and drawing on earlier secondary data, a longitudinal analysis of changes in governance and livelihoods is undertaken. Increased exploitation of marine resources has widened the resource base and increased people's access to goods and services. Following the ban in 2005 on the bêche-de-mer trade, however, livelihoods have reverted to being more subsistence oriented. For almost two decades after 1978, a communal organization, the Area Council, succeeded in regulating exploitation of the atoll's marine resources to ensure sustainable use, but in the 1990s it collapsed. In addition there was a paralysis of institutions that had once settled land disputes. This failure of atoll governance is a greater threat to future 'sustainability' than the usual processes that are invoked for atolls and small islands generally. As the Solomon Islands state is also failing, we argue that local institutions and organizations have a vital role to play in managing access to resources and the future of livelihoods on Ontong Java atoll.     

Factors controlling the survival of coastal dunes during multiple hurricane impacts in 2004 and 2005: Santa Rosa barrier island, Florida

Santa Rosa Island is an 85 km-long, wave-dominated low-lying barrier island situated along the northwestern Florida coast, facing the Gulf of Mexico. The entire island was severely impacted by Ivan, a strong category 3 hurricane that made landfall about 45 km to the west in September of 2004. Ten months later in July of 2005, Dennis, another category 3 hurricane, made landfall about 30 km east of the western tip of the island. Santa Rosa Island is characterized by well-developed but relatively low dunefields, described in this paper as incipient and established dunes, based on the presence of grassy and woody types of vegetation, respectively. The dunes were severely eroded by the two hurricanes. This paper investigates the factors controlling the regional-scale destruction and survival of the dunefields.Dune survival is controlled by: 1) hurricane characteristics, including intensity, duration, and frequency, and 2) morphological parameters including width of the barrier island, height and width of the dunefields, vegetation type, distance of the dunes to the ocean, and continuity of the dunefields. Three processes of dune destruction are described including, from most to least severe, inundation, overwash, and scarping. The interaction of all the above factors determines the different dune responses to the storm impacts. In general, the extensive and densely woody vegetated dunefields near the bay-side shoreline survived the storms, while the discontinuous dunes with grassy vegetation near the Gulf shoreline were almost completely destroyed.     

Catastrophic hurricane history revealed by organic geochemical proxies in coastal lake sediments: a case study of Lake Shelby,Alabama (USA)

We developed a new method for reconstructing millennia-long hurricane records from coastal environments that uses Organic Geochemical Proxies (OGPs) of organic carbon and nitrogen concentrations and their δ¹³C and δ¹⁵N compositions. The new method is independent of presence/absence of sand layers and improves significantly the severe-storm history resolution. The subject of this investigation is a 1.5 m long sediment core raised at 2.8 m water depth from the center of Lake Shelby, Alabama, a freshwater lake located approximately 250 m from the Gulf of Mexico, from which an overwash sand-layer based record was previously derived. The core contains two distinct sediment units; an upper 62 cm thick, fine-grained, organic-rich lacustrine sapropel (gyttja) that shows no visible structures except one sand lamina at 23.7 cm depth, and an underlying 90 cm thick, organic-poor lagoon/estuary clay unit. The sapropel unit was deposited over a 682 ± 30 cal year time interval (1320–2002 A.D.) with a mean sedimentation rate of 0.79 ± 0.04 mm/year. Lake Shelby’s water column exhibits two contrasting states based on water chemistry surveys (i) an “isolated”, stratified, mode under calm weather conditions with a relatively low trophic state, and (ii) a “flooded” mode occurring during storm surges when nutrient-rich seawater floods the lake. Statistically significant δ¹³C and δ¹⁵N positive excursions in organic matter, up to maximum values of −25 (‰ PDB) and 4 (‰ Air N₂), respectively, are interpreted as geochemical responses to the marine intrusions that fertilize the lake, increase light availability, and cause eutrophication spikes. Detailed OGPs analyses crossing a sand layer that offers visual evidence of a catastrophic hurricane overwash event at 1717 A.D. exhibit large δ¹³C and δ¹⁵N positive shifts bounded by rapid returns to base values, thus confirming the validity of the hurricane identification by the OGPs model. Our data indicate that 11 catastrophic hurricanes hit the Alabama coast over the past 682 years with a rough recurrence interval of one in 62 years.     

新疆伊犁黄土的物性指标、动力学特性与滑坡

分析了伊犁谷地28个黄土样品的粒径、密度、含水量和孔隙比,测试了震陷、湿陷、动弹模量和塑性指数,探讨了伊犁谷地黄土的物性、动力学特征,讨论了它们与滑坡之间的关系。伊犁谷地的原生黄土主要以粉粒为主,含量为74%,大于75μm的颗粒含量为10%,小于5μm的颗粒含量为15%;黄土天然含水量为4%~16.1%,谷地东部的黄土明显地比谷地西部的更细,伊犁黄土的孔隙比在0.832~0.907之间,有相当的湿陷性。在含水量低于20%时,还会有湿陷。黄土的塑性指数为9左右,比较小,粘粒含量低,易损性大,抗震性能差,具有较强的震陷性。在同样的动应变下,伊犁黄土的动模量较小,随着动应变的增大,其动模量衰减较快。冻融季节是伊犁地区滑坡的多发季节,构造活动强烈的地段也是地质灾害的多发地段。     

Physical Landscape in Tachienlu, Kowlon and Litang, Sikang Province.

The region under discussion lies in the eastern border of the Tibetan Plateau. andhas been deeply di(?)sected by the Tatu Ho, Yalung Kiang and their triibutaries. Deep canyons and the flat plateaus form strong contrast in topography. Some native terms have been wisely used, such as, Koaga for glaciated mountains and peaks,“Tang” for bare rock region, “Tsu” for alp pasture, “Kan” for precipitous valley slope, and “Lon” for stream channel.     

Basement controls upon basin development in the Caledonian foreland, NW Scotland

Abstract The Hebridean basins are part of a compartmentalized half-graben developed in the hanging wall of the partially reactivated Outer Isles Fault. The importance of geological inheritance in the development of these basins can be demonstrated clearly using the widespread exposure of metamorphic basement around the basin margins. The basement structures have been analysed using thematically mapped Landsat images in conjunction with selective field studies. Results of such studies have been integrated with maps generated from the interpretation of offshore multichannel seismic reflection profiles to produce an architectural framework for basin development.
It can be demonstrated that the principal basement faults originated in the early Proterozoic as mid-crustal shear zones and that they have subsequently been partially reactivated during post-Caledonian basin development beginning in the Carboniferous and probably also during an earlier period of basin development in the late Proterozoic (the Torridonian). It is the geometry of the pre-existing basement structures that has controlled the three-dimensional shape of the sedimentary basins and the spatial and temporal distribution of the basin fill.     

张掖市水资源实物型投入产出表的编制应用

实物型投入产出模型更适合用于核算与量化分析经济系统与资源环境间直接及间接的耦合关联。采用Helga Weisz的方法,通过价值型向实物型表转换,编制完成张掖市实物型投入产出表。基于实物型投入产出模型,对张掖市各部门水资源利用在社会经济系统中迁移特点和部门关联程度及乘数进行分析。结果表明：实物表为我们提供了新的分析视角,此方法的应用在资源环境领域的应用具有相当的适用价值。间接需求对水资源影响不容忽视,每个部门的乘数作用很大程度影响该部门在虚拟水战略中的地位和作用。畜牧业、制造业、建筑业在张掖市水资源利用部门关联中作用突出,应作为水资源的社会化管理重点关注的部门。     

中国天山西部季节性森林积雪物理特性

积雪特殊的物理特性对冰雪水文过程、积雪生态系统、不同尺度的气候系统有重要影响。目前对林下积雪物理特性缺乏系统性研究,因此对天山雪岭云杉林下季节性积雪深度、沉降速率、密度和含水率进行观测分析。结果表明：林下积雪深度小于开阔地;林下积雪沉降速率和新雪密实化率小于开阔地,且稳定期沉降速率小于融雪期。稳定期林下积雪密度小于开阔地,林下雪层密度最大值位于中粒雪层,开阔地则位于粗粒雪层;融雪期则全层密度趋于一致。稳定期林下雪层含水率随深度递减,开阔地雪层最大值出现粗粒雪层;融雪期雪层汗水峰值出现在细粒雪层,新雪层最小,林下雪层由细粒雪层到深霜层始终呈减小趋势,开阔地雪层由细粒雪层至中粒雪层逐渐减小,粗粒雪层至深霜层逐渐增大;稳定期雪层含水率日变化随深度的递减逐渐减小,开阔地大于林下;开阔地的新雪层和细粒雪层含水率的日变化大于林下,粗粒雪层到深霜层则小于林下。     

呼伦贝尔沙质草原表土物理力学性质

通过野外现场调查、载荷试验、轻型圆锥动力触探及室内试验,对呼伦贝尔沙质草原厚度30 cm的表层沙土物理力学性质及承载力、剪切变形特征进行研究。结果表明:表层沙土工程分类为细砂,颗粒级配不良,沿深度有明显分层;干密度1.34～1.51 g·cm^-3,黏聚力12～27.4 kPa,内摩擦角22.5°～24.0°,变形模量8.5 MPa;各指标表明沙土的工程性质上部差于下部;沙土承载力特征值和极限承载力分别为150 kPa和300 kPa,承载力不足导致表层沙土发生冲剪破坏(塑性破坏)和整体剪切破坏(脆性破坏)。     

四川紫色土丘陵区农林系统的水土保持作用

以中科院盐亭紫色土农业生态试验站的历年有关资料为基础 ,研究结果表明 :林地侵蚀模数较草地的高出约 30 % ,径流模数则减少 4 5 % ;林区耕地的侵蚀模数和径流模数较草地耕地的分别减少约 70 %和 2 5 % ,表明农林复合生态系统 (AAS)对耕地有较明显的水土保持作用。农林复合生态系统其年均径流量为非农林复合系统 (NAAS)的 1 2 ,洪峰模数相对后者削减约 4 0 % ,表明该系统对削减流域径流及其洪峰和防洪有明显作用。     

Mapping Soils,Vegetation, and Landforms: An Integrative Physical Geography Field Experience*

Students in a graduate seminar at Michigan State University produced a series of detailed vegetation, soils, and landform maps of a 1.5‐square‐mile (3.9 km²) study area in southwest Lower Michigan. The learning outcomes (maps) and skill development objectives (sampling strategies and various GIS applications) of this field‐intensive mapping experience were driven by the assumption that students learn and understand relationships among physical landscape variables better by mapping them than they would in a classroom‐based experience. The group‐based, problem‐solving format was also intended to foster collaboration and camaraderie. The study area lies within a complex, interlobate moraine. Fieldwork involved mapping in groups of two or three, as well as soil and vegetation sampling. Spatial data products assembled and used in the project included topographic maps, a digital elevation model (DEM), aerial photographs, and NRCS (National Resource Conservation Service) soil maps. Most of the soils are dry and sandy, with the main differentiating characteristic being the amount of, and depth to, subsurface clay bands (lamellae) or gravelly zones. The presettlement (early 1830s) vegetation of the area was oak forest, oak savanna, and black oak “barrens.” Upland sites currently support closed forests of white, black, and red oak, with a red maple, dogwood, and sassafras understory. Ecological data suggest that these oak forests will, barring major disturbance, become increasingly dominated by red maple. This group‐based, problem‐solving approach to physical geography education has several advantages over traditional classroom‐based teaching and could also be successfully applied in other, field‐related disciplines.     

Physical properties, spectral reflectance and thickness development of first year fast ice in Kongsfjorden, Svalbard

A ground truth study was performed on first year fast ice in Kongsfjorden, Svalbard, during spring 1997 and 1998. The survey included sea ice thickness monitoring as well as observation of surface albedo, attenuation of optical radiation in the ice, physical properties and texture of snow and sea ice. The average total sea ice thickness in May was about 0.9 m, including a 0.2 m thick snow layer on top. Within a few weeks in both years, the snow melted almost completely, whereas the ice thickness decreased by not more than 0.05 m. During spring, the lower part of the snow refroze into a solid layer. The sea ice became more porous. Temperatures in the sea ice increased and the measurable salinity of the sea ice decreased with time. Due to snow cover thinning and snow grain growth, maximum surface albedo decreased from 0.96 to 0.74. Texture analysis on cores showed columnar ice with large crystals (max. crystal lenght > 0.1 m) below a 0.11 m thick mixed surface layer of granular ice with smaller crystals. In both years, we observed sea ice algae at the bottom part of the ice. This layer has a significant effect on the radiation transmissivity.     

LiB_5O_8溶液物理化学性质研究

根据Li2O-B2O3-H2O多温相图合成晶体LiB5O8·5H2O。在从稀到饱和浓度范围内测定LiB5O8水溶液在40℃和50℃下的物化性质(密度、粘度、电导率和p H),并根据相应的模型进行关联。根据文献的化学平衡常数以及测定的p H值,计算出硼酸盐溶液中存在的B(OH)3、B(OH)-4、B3O3(OH)-4、B4O5(OH)2-4和B5O6(OH)-4等物种各浓度下的摩尔分数,并给出溶液中可能存在的反应及其相应的机理。