甘肃靖远—景泰泥盆系湖相风暴岩及其古地理意义

甘肃靖远-景泰一带泥盆系雪山组和沙流水组以河湖相碎屑岩为主,内发育典型的风暴沉积构造(包括渠铸型、槽筑型、丘状交错层理和洼状交错层理、平等层理、块状层理和递变层理等).雪山组和沙流水组的风暴沉积主要包括3种岩相类型A底部具渠铸型或槽筑型的块状层理和递变层理砂岩.B具丘状或洼状交错层理及平行层理的砂岩.C具均质层理的粉砂岩、泥质岩.上述岩相A,B,C分别代表风暴事件沉积中风暴流行作用-风暴后的快速悬浮沉积(事件沉积),它们组合成典型的风暴沉积序列.甘肃靖远一带晚加里东早海西期位于北祁连造山带北缘同造山盆地的构造背景下,泥盆纪雪山组-沙流水组以河湖相沉积为主.泥盆纪湖相风暴岩的发现表明该区处于低纬度(5.～20.)的风暴作用带.中、晚泥盆世北祁连造山带构造隆升渐弱,海拔不高,不足以阻隔风暴作用对山后湖盆的侵扰.因此在近海湖盆中形成风暴岩沉积.该沉积对于认识北祁连河西走廊泥盆纪的古地理、古气候及古构造具有重要意义.     

甘肃靖远─景泰泥盆系湖相风暴岩及其古地理意义

甘肃靖远景泰一带泥盆系雪山组和沙流水组以河湖相碎屑岩为主 ,内发育典型的风暴沉积构造 (包括渠铸型、槽筑型、丘状交错层理和洼状交错层理、平等层理、块状层理和递变层理等 )。雪山组和沙流水组的风暴沉积主要包括 3种岩相类型 :A底部具渠铸型或槽筑型的块状层理和递变层理砂岩。 B具丘状或洼状交错层理及平行层理的砂岩。C具均质层理的粉砂岩、泥质岩。上述岩相 A,B,C分别代表风暴事件沉积中风暴流行作用 -风暴后的快速悬浮沉积 (事件沉积 ) ,它们组合成典型的风暴沉积序列。甘肃靖远一带晚加里东 -早海西期位于北祁连造山带北缘同造山盆地的构造背景下 ,泥盆纪雪山组 -沙流水组以河湖相沉积为主。泥盆纪湖相风暴岩的发现表明该区处于低纬度 (5°～ 2 0°)的风暴作用带。中、晚泥盆世北祁连造山带构造隆升渐弱 ,海拔不高 ,不足以阻隔风暴作用对山后湖盆的侵扰。因此在近海湖盆中形成风暴岩沉积。该沉积对于认识北祁连 -河西走廊泥盆纪的古地理、古气候及古构造具有重要意义     

海南岛东南部海岸砂丘风暴冲越沉积记录

通过海南岛东南部海岸详细的古风暴学考察,在尖岭海岸发现了含有风暴冲越沉积物的海岸沙丘剖面,分别命名为JL-1和JL-2剖面,试图从海岸沙丘沉积记录中提取历史上的风暴事件信息。沉积物粒度、磁化率等参数的指标分析表明,这两个剖面含有典型的风暴冲越沉积物,利用放射性核素AMS14C测年、OSL测年分析,并结合历史文献记载,确定这些风暴沉积层是多次台风作用的产物,其形成机制与风暴浪越过海岸沙丘的堆积有关,风暴流越过沙丘顶部后不能回流,导致风暴流携带的沉积物迅速沉积。此外,依据Stockdon经验公式计算结果,该地点沉积记录所代表的最大风暴事件相当于100到200年一遇的重现期。研究表明,该处海岸沙丘冲越沉积含有南海台风强度与重现期的重要信息。     

古氧相——一个新的沉积学研究领域

简要介绍了富氧相、贫氧相、厌氧相、外富氧相和这氧相的主要特征、成因及目前古氧相分析的主要途径，包括古生态学、遗迹学、有机相和沉积地球化学分析。根据国内外研究资料，结合笔者科研成果，综述了古氧相在今地球科学研究领域，如层序地层、岩相古地理编图、重要地质事件研究及地史恢复中的应用及其前景。     

风暴岩研究述评兼论兴文风暴岩研究的意义

风暴岩自1973年G.Kelling提出以来,其研究得以迅速发展,特别是建立的风暴流理论与50年代出现的浊流理论一样,被公认为沉积学乃至地质学发展的里程碑。本文回顾了国内外风暴岩研究的历程、现状,着重综述了国内外对风暴岩研究的起源、定义,及风暴岩的沉积成因、沉积序列、沉积构造和研究意义;分析了风暴岩的形成环境和研究尺度,对未来风暴岩研究的启示,并探讨了兴文风暴岩研究对兴文世界地质公园的意义。     

下扬子区三叠纪海洋风暴沉积与古地理演变

下扬子区三叠纪海洋风暴沉积与古地理演变钱迈平，郭佩霞地质科学院南京地矿所，南京，２１００１４关键词：风暴沉积，古地理演变，下扬子区，三叠纪．中国东部。ＰａｌｅｏｇｅｏｇｒａｐｈｉｃＥｖｏｌｕｔｉｏｎａｎｄＭａｒｉｎｅＳｔｏｒｍＤｅｐｏｓｉｔｓＰｒｅｓ...     

西湖凹陷古近系花港组风暴沉积研究

通过岩心观察,发现花港组典型的风暴沉积构造主要包括风暴侵蚀形成的渠模、冲刷沟槽、冲刷面,风暴涡流形成的撕扯构造、菊花状构造,风暴重力流形成的粒序层理,风暴浪形成的丘状交错层理、浪成沙纹层理、平行层理,同生变形构造及生物逃逸构造.运用岩石相组合分析的方法,发现花港组风暴垂向沉积序列发育不完整.其理想的序列由A~G共7段构成。根据花港组垂向沉积序列类型、沉积构造特点总结出了A+B+G、A+B+C、A+B+D、B+C+D、C+E+G、E+F+G等6种风暴沉积序列和原地风暴岩、近源风暴岩和远源风暴岩3种风暴岩类型.     

风暴沉积的遗迹学研究

遗迹化石正在证明其在鉴别和解释事件地层中的作用。风暴沉积含有一套混合的、与能量水平变化相适应的遗迹化石组合,两种不同的遗迹群落反映变化着的行为方式对生物所移居的两种连续的,但是单个性质不同的生境所作出的反应:常住的或平常天气的遗迹群落可以作为一种稳定的底栖群落的代表,在这一群落里单个的居群达到或接近它们的承载能力;而周期性产生的风暴遗迹群落则代表着在一种不稳定的、生态环境恶化的、机械控制的环境下繁盛的机会主义生物的群落。典型的陆源碎屑的风暴沉积中的遗迹群落可以加拿大艾伯塔上白垩统卡迪组中的遗迹群落为例,而碳酸盐风暴沉积中的遗迹群落则可以中国华北地台东部上寒武统崮山组中的碳酸盐风暴沉积序列中的遗迹群落为例,本文详细介绍这两种类型的成因及结构、构造特点。     

柴达木盆地西部古近系湖相风暴岩

在野外剖面和岩心观察基础上,介绍了柴达木盆地西部古近系湖相风暴岩沉积特征,建立了湖泊风暴沉积模式,探讨风暴岩发育条件及意义.研究区风暴沉积是由风暴浪作用于浅湖泥坪上,使沉积物搅起、形成泥岩砾屑,并通过风暴流搬运到三角洲或滨浅湖滩坝中,与未固结砂质沉积物一起沉积形成.其典型沉积构造特征丰富,单层风暴沉积发育不完整,常见多次风暴作用形成若干不完整风暴岩叠置层.风暴岩的发现有利于加深对该区沉积相的认识,风暴岩频繁发育,表明研究区在古近系沉积时,易受到古气候影响,湖盆水动力较强,部分原始沉积砂体会受到湖泊水体的改造,形成新的滨浅湖滩坝砂体,形成良好的岩性油气藏.     

Passage of Tropical Storm Allison (2001) over southeast Texas recorded in δO values of Ostracoda

Freshwater Ostracoda collected in ephemeral pond-waters derived from Tropical Storm Allison (2001, Texas) recorded the unusually low oxygen-isotope values of that storm. Therefore, the potential clearly exists, in locations where tropical cyclones make landfall, to obtain a long-term record of tropical cyclone activity from fossil ostracode calcite.     

热带珊瑚的高分辨率环境信息与全球变化研究进展

星罗棋布的热带珊瑚作为海洋环境的信息载体,具有分辨率高、时间跨度大、记录连续完整、体系封闭性好、蕴涵的信息丰富、可选择的代用指标多、测定简便和易于定年等特点。珊瑚有效地记录了全球环境变化的诸多信息,已成为研究过去（如末次间冰期以来）和近代（如数十至数百年以来）的气候—环境变率和可预测性（PAGES CLIVAR）领域重要的环境载体。以全球变化为背景,对近年来珊瑚环境代用指标的研究成果进行评述。重点讨论了珊瑚氧同位素和微量元素比值等指标在海表温度（SST）变化、海气交换程度、季风强弱、厄尔尼诺—南方涛动（ENSO）发生的频率和强度,以及它们之间的相互作用等全球变化的核心问题上的研究进展,并展望了南海珊瑚在高分辨率全球变化研究中的地位与方向。     

Vulnerability from storm surges and cyclone wind fields on the coast of Andhra Pradesh,India

The results presented here are from a study conducted for the government of the state of Andhra Pradesh (GOAP) in India, as part of a World Bank project on cyclone mitigation. A set of detailed maps were prepared depicting the Physical Vulnerability (PV), specifically storm surge inundation zones are shown for frequent occurrence, 50-year return period, likely scenario for global warming and extreme global warming. Similarly vulnerable areas from strong wind field from tropical cyclones (TCS) are also presented for the same four parameters. Vulnerability zones are presented from a social point of view also based upon certain socio-economic parameters that were included in determining the overall vulnerability of each Mandal in a coastal district (a Mandal represents a group of villages and towns) include: population, senior citizens, women, children under different age groups, type of housing, income level, cyclone shelters, hospitals and medical centres, schools and caste based population. The study is about scenarios that could happen if global warming and the predicted intensification of TCS actually occur as predicted by some numerical models.     

Impact of horizontal resolution on prediction of tropical cyclones over Bay of Bengal using a regional weather prediction model

The present study is carried out to examine the performance of a regional atmospheric model in forecasting tropical cyclones over the Bay of Bengal and its sensitivity to horizontal resolution. Two cyclones, which formed over the Bay of Bengal during the years 1995 and 1997, are simulated using a regional weather prediction model with two horizontal resolutions of 165 km and 55 km. The model is found to perform reasonably well towards simulation of the storms. The structure, intensity and track of the cyclones are found to be better simulated by finer resolution of the model as compared to the coarse resolution. Rainfall amount and its distribution are also found to be sensitive to the model horizontal resolution. Other important fields, viz., vertical velocity, horizontal divergence and horizontal moisture flux are also found to be sensitive to model horizontal resolution and are better simulated by the model with finer horizontal grids.     

Impact of modification of initial cyclonic structure on the prediction of a cyclone over the Arabian Sea

Most tropical cyclones have very few observations in their vicinity. Hence either they go undetected in standard analyses or are analyzed very poorly, with ill defined centres and locations. Such initial errors obviously have major impact on the forecast of cyclone tracks using numerical models. One way of overcoming the above difficulty is to remove the weak initial vortex and replace it with a synthetic vortex (with the correct size, intensity and location) in the initial analysis. The objective of this study is to investigate the impact of introducing NCAR–AFWA synthetic vortex scheme in the regional model MM5 on the simulation of a tropical cyclone formed over the Arabian Sea during November 2003. Two sets of numerical experiments are conducted in this study. While the first set utilizes the NCEP reanalysis as the initial and lateral boundary conditions, the second set utilizes the NCAR–AFWA synthetic vortex scheme. The results of the two sets of MM5 simulations are compared with one another as well as with the observations and the NCEP reanalysis. It is found that inclusion of the synthetic vortex has resulted in improvements in the simulation of wind asymmetries, warm temperature anomalies, stronger vertical velocity fields and consequently in the overall structure of the tropical cyclone. The time series of the minimum sea level pressure and maximum wind speed reveal that the model simulations are closer to observations when synthetic vortex was introduced in the model. The central minimum pressure reduces by 17 hPa while the maximum wind speed associated with the tropical cyclone enhances by 17 m s ⁻¹ with the introduction of the synthetic vortex. While the lowest central pressure estimated from the satellite image is 988 hPa, the corresponding value in the synthetic vortex simulated cyclone is 993 hPa. Improvements in the overall structure and initial location of the center of the system have contributed to considerable reduction in the vector track prediction errors ie. 642 km in 24 h, 788 km in 48 h and 1145 km in 72 h. Further, simulation with the synthetic vortex shows realistic spatial distribution of the precipitation associated with the tropical cyclone.     

Advances and Challenges in the Study on the Tropical Rainfall Changes Under Global Warming*

Since tropical rainfall is important in the global energy and hydrologic cycle, the tropical rainfall changes under global warming have attracted extensive attention around the world in recent decades. The advances in the observational studies and model projection for the tropical rainfall changes under global warming were reviewed here. The frontiers in the mechanism of regional tropical rainfall changes and the approaches of rainfall change research are summarized. The large intermodel spread in the multi-model projections, the sources of uncertainty and the methods to reduce the uncertainty were also introduced. Finally, the challenges about the tropical rainfall changes were discussed.     

Impact of various synthetic vortices on cyclone track prediction

Sensitivity experiments are conducted for three cases of cyclones for investigating the impact of different vortex initialization schemes on the structure and track prediction of the cyclone using India Meteorological Department’s Limited Area Model. The surface wind and pressure profiles generated using Holland and Rankine initialization schemes differ from each other. These different generated profiles are compared with the actual data and the root mean square error (RMSE) was calculated between them. In case of the Holland vortex, ‘b’ is found to be equal to 1.5 and 2.0 respectively for two cases of very severe cyclonic storms in the Arabian Sea, namely 6–10 June 1998 and 16–20 May 1999 and 2.25 for the severe cyclonic storm in the Bay of Bengal. The ‘α’ parameter in Rankine’s scheme was found to be 0.5 for two cases and 0.4 for the third system. This shows that cyclones differ even if they attain the same intensity. The values of these parameters i.e. ‘b’ and ‘α’ are used for generating the synthetic wind data for individual cyclones and the same is used in the data assimilation system. The analysis and forecast generated for the above cases using the Holland scheme show that the simulated structure has characteristics closer to the actual storm; however, the Rankine scheme shows a weaker circulation. The mean track error for three cases in the Holland scheme is 93, 149, 257 and 307 km in 12-, 24-, 36- and 48-h forecast. The mean track errors for the Rankine scheme are 152, 274, 345 and 327 km, respectively, for the same period.     

Occurrence of landslides during the approach of tropical cyclone Juliette (2001) to Baja California Sur,Mexico

The approach of tropical cyclone (TC) Juliette, in 2001, to the Baja California Peninsula triggered at least 419 landslides. Most of the landslides were shallow slips and debris slides of limited areal extent, which were converted rapidly into debris flows to be exported quickly out of the mountain areas towards the lowlands. Main factors affecting landslide occurrence were total storm rainfall and intensity, aspect, geology and vegetation association. Two processes can be distinguished as initiating slope failure. Accumulation of rainfall from exposed bedrock slopes, generating excess overland flow, was the main process linked to failures in concave topography. A combination of wind and excess overland flow in the more convex or planar upper slopes was a secondary process related to heterogeneity of vegetation associations in the oak-dry tropical forests ecotone, as uprooted trees dislodged large regolith and bedrock blocks, priming hillslopes for further runoff concentration. An estimative threshold curve for triggering landslides in this region is sketched. From the analysis of historical information, storms like Juliette approach the southern peninsula on average once every 100 years. Denudation estimates are in the higher end of the spectrum for a tectonically passive margin. These estimates should be considered when taking decisions regarding management of water resources in this area through damming of streams. The results emphasize the need for a more detailed representation of the spatial distribution of the rainfall and winds for this mountainous region affected by TCs.     

无人飞机在台风探测中的应用进展

与有人飞机的台风探测不同,无人飞机(也称无人机)因其相对低的成本且无人员伤亡风险等优势,自1997年一款名为"气象侦察兵(Aerosonde)"投入台风探测试验以来,受到国际社会的广泛关注。随着无人机技术的迅猛发展,无人机的飞行高度、有效荷载和续航能力等性能不断提高,更多的台风特种观测仪器被搭载,特别是2010年NASA使用高空长航时无人机"全球鹰(Global Hawk)"对大西洋5个飓风的飞行探测取得成功后,基于无人机平台建立高空下投探空和近地/水面飞行观测相结合的台风精细结构探测体系渐成趋势。目前我国尚未建立飞机探测台风的业务,严重制约了我国台风定位定强和台风数值预报精度的进一步提高。鉴于此,简要概述了境内外无人机在台风探测中的实践和发展趋势,旨在推进我国无人机探测台风的实践及其业务化体系的建设。     

A statistical cyclone intensity prediction (SCIP) model for the Bay of Bengal

A statistical model for predicting the intensity of tropical cyclones in the Bay of Bengal has been proposed. The model is developed applying multiple linear regression technique. The model parameters are determined from the database of 62 cyclones that developed over the Bay of Bengal during the period 1981–2000. The parameters selected as predictors are: initial storm intensity, intensity changes during past 12 hours, storm motion speed, initial storm latitude position, vertical wind shear averaged along the storm track, vorticity at 850 hPa, Divergence at 200 hPa and sea surface temperature (SST). When the model is tested with the dependent samples of 62 cyclones, the forecast skill of the model for forecasts up to 72 hours is found to be reasonably good. The average absolute errors (AAE) are less than 10 knots for forecasts up to 36 hours and maximum forecast error of order 14 knots occurs at 60 hours and 72 hours. When the model is tested with the independent samples of 15 cyclones (during 2000 to 2007), the AAE is found to be less than 13 knots (ranging from 5.1 to 12.5 knots) for forecast up to 72 hours. The model is found to be superior to the empirical model proposed by Roy Bhowmik et al (2007) for the Bay of Bengal.