珠江流域1961-2007年气候变化及2011-2060年预估分析

 根据珠江流域1961-2007年气温、降水量观测资料和ECHAM5/MPI-OM模式2011-2060年预估结果,分析了流域过去47 a的气温和降水量变化,并预估未来50 a变化趋势。结果表明,在全球变暖的背景下,过去47 a温度呈上升趋势,约升高1.8℃。冬季增温最明显,夏季最弱。未来50 a流域温度仍呈上升趋势,A1B情景下升幅约1.9℃,并且年际变化增强。A2和B1两种排放情景下秋季升温最显著,冬季最弱,A1B排放情景与此相反。过去47 a秋季降水量呈减少趋势;春、夏、冬季和年降水量均呈增加趋势。未来50 a降水总体呈增加趋势,A1B排放情景降水增加最多,约为230 mm。A2、A1B和B1情景下降水季节分配未发生显著变化。年降水和冬季降水的年际变率增强,秋季减弱。     

Atmospheric effects from post-nuclear fires

During a large nuclear war, the atmosphere would be loaded with huge quantities of pollutants, which are produced by fires in urban and industrial centers, cultivated lands, forests and grasslands. Especially detrimental are the effects of light absorbing airborne particles. An analysis of the amounts of the various types of fuels which could burn in a nuclear war indicates that more than 10¹⁴ g of black smoke could be produced by fires started by the nuclear explosions. Due to this, the penetration of sunlight to the earth's surface would be reduced greatly over extended areas of the northern hemisphere, maybe even globally. This could temporarily cause extreme darkness in large areas in midlatitudes and reduce crop growth and biospheric productivity.This situation would last for several weeks and cause very anomalous meteorological conditions. Much solar radiation would be absorbed in the atmosphere instead of at the earth's surface. The land areas and lower atmosphere would, therefore, cool and the overlying atmosphere warm, creating strong vertical thermal stability in a highly polluted atmosphere. For extended periods and in large parts of the world, weather conditions would be abnormal. The resulting cold, probably freezing, temperatures at the ground would interfere severely with crop production during the growing season and cause extreme conditions for large sections of the biosphere. The combination of lack of sunlight, frost and other adverse meteorological conditions would add enormously to the already huge problems of the survivors.     

基于CERES观测数据的全球行星反照率时空变化特征分析

为了理解行星反照率时空变化规律及成因,基于CERES数据对全球行星反照率的大气(主要为云与气溶胶等)和地表贡献进行了分解,通过Theil-Sen+Mann-Kendall方法得到了2001～2018年全球行星反照率及其大气和地表贡献的时空变化趋势,并基于回归分析方法对典型区域的变化趋势进行了初步解释.研究结果表明:1)...     

Shallow sediment deformation styles in north-western Campeche Knolls,Gulf of Mexico and their controls on the occurrence of hydrocarbon seepage

During German R/V Meteor M67/2 expedition to Campeche Knolls, southern Gulf of Mexico, a set of 2D high resolution seismic data was acquired to study the near-surface sediment structure and its relationship with hydrocarbon seepages in this salt province. The comprehensive survey covered 20 individual bathymetric highs or ridges and identified three principle structural types: Passive Type, Chaopopte Type, and Asymmetric Flap Type. The first type is the result of passive diapirism, whereas the latter two were initialized by a regional compressional event in the Miocene, but are later differently modified by salt tectonism. Chapopote Type structures appear as symmetrical domes, with uplifted coarse-grained Miocene sediments in their cores and rather thin syn-kinematic sediments covering the crests. Asymmetric Flap Type structures are also first folded as domes or ridges, but one flap later subsided together with salt evacuation, resulting in single uplifted monoclines. With the coarse-grained pre-kinematic sediments as reservoir units, both structural types can focus and accumulate hydrocarbons. The geometries of the structures suggest that hydrocarbons are accumulated in the center of the Chapopote Type structures and in the subsided flaps of the Asymmetric Flap Type structures. Hydrocarbon leakage from these thinly sealed reservoirs is regarded as the principle mechanism for the seepage in the study area, and accordingly the most seepage-prone positions are above these reservoirs. The seep locations suggested by analysis of sea-surface oil slick images of SAR satellite data are also examined in this study. These independently derived seep locations confirm the seepage-prone positions to be above the shallow buried reservoirs. This study suggest that the shallow sediment structures control the distribution of the hydrocarbon seeps of the north-western Campeche Knolls, although the hydrocarbons are sourced from the greater depth.     

Exploring the spatial distribution patterns of South African Cape hakes using generalised additive models

We developed delta generalised additive models (GAMs) to predict the spatial distribution of different size classes of South African hakes, Merluccius capensis and M. paradoxus, using demersal trawl survey data and geographical (latitude and longitude) and environmental features (depth, temperature, bottom dissolved oxygen and sediment type). Our approach consists of fitting, for each hake size class, two independent models, a binomial GAM and a quasi-Poisson GAM, whose predictions are then combined using the delta method. Delta GAMs were validated using an iterative cross-validation procedure, and their predictions were then employed to produce distribution maps for the southern Benguela. Delta GAM predictions confirmed existing knowledge about the spatial distribution patterns of South African hakes, and brought new insights into the factors influencing the presence/absence and abundance of these species. Our GAM approach can be used to produce distribution maps for spatially explicit ecosystem models of the southern Benguela in a rigorous and objective way. Ecosystem models are critical features of the ecosystem approach to fisheries, and distribution maps constructed using our GAM approach will enable a reliable allocation of species biomasses in spatially explicit ecosystem models, which will increase trust in the spatial overlaps and, therefore, the trophic interactions predicted by these models.     

Accuracy assessment of noise mapping on the main street

Among the sounds constituting a part of our daily lives, the undesired and disturbing ones are named noise. The noises can be defined as the acoustic energy that affects the physiological and psychological welfare of humans due to its direct or indirect effects on the human health. But, the traffic noise, which is one of the disturbing noises having wide dispersion in urban areas, affects the health of a gradually increasing number of people. The number of studies on measurement, dispersion, and mapping of traffic noise in developed and developing countries is gradually increasing. It can be seen that the studies concentrate on mapping based on the city centers and neighborhoods, where the traffic is intense. In this article, unlike the regional noise measurement studies, the transversal cross sections were established with a certain interval according to the land status along the main street, and the noise measurement points were determined using the global navigation satellite system (GNSS). The daily mean noise levels (L_den) were calculated by performing the measurements at daytime, evening, and nighttime. Using ArcGIS 10.4 software, the accuracy of noise maps created via inverse distance weighting (IDW), radial basis function (RBF), and ordinary kriging (OK) geostatistical analysis interpolation methods and the dispersion effect of traffic noise were compared. According to the visual method and error corrections, it was found that the best noise map was obtained using the RBF method. It is believed that the map provides accurate and reliable results because of the flat land surface, higher noise values measured on the road region, decrease in the noise at the points farther from the road region, and soft transitions between the noise values depending on the distance from the road. In order to take measures in order to decrease or eliminate noise on the main street, the local administrators and decision-makers can make use of these maps, the accuracy of which has been confirmed.     

‘Filament’ marker beds in the Karababa-A Member (Turonian) of the Arabian platform,SE Turkey: Palaeo-environmental significance,stratigraphy and correlation potential

A ‘filament’ event bed/level corresponds to the occurrence of thin elongate calcitic, shells, or plates of pelagic, bivalve or crinoidal, origin, within pelagic, laminated and organic-matter rich limestones. These organic-rich limestones had been generally deposited under hypoxic/anoxic conditions in an outer-ramp environment. These thin elongate, bivalve shells, or crinoidal plates, are found broken in small pieces, disintegrated, or simply preserved parallel to bedding as almost complete specimens. Such ‘filament’ beds were spotted in SE Turkey in deposits, namely the Karababa-A Member, around the Cenomanian-Turonian boundary (C/TB) and above. On a global scale, these filament event beds illustrate sea-level rise related to eustacy and/or climatic change. The abundance of filaments close to the C/TB is a biological marker of high organic productivity resulting from a climatic change to warmer conditions. The prevailing higher sea-level conditions were then favourable to the accumulation and preservation of organic-rich facies, characteristic of the Oceanic Anoxic Event 2 (OAE2). Using both biostratigraphic and carbon isotopic data, those deposits were dated from the latest Cenomanian-Turonian age. ‘Filament’ event beds were recorded in the same order, except for some small differences. A good number of these bio-events are global. Consequently, on a global scale, they are susceptible to constrain the C/TB, especially the base of the Turonian stage, with a significant degree of confidence.