Sorted stripes orientated by wind action: Some observations from sub-antarctic marion island     

Kevin Hall 《地球表面变化过程与地形》1979,4(3):281-289

Sorted stripes found on the volcanic scoria and glacial deposits of sub-Antarctic Marion Island indicate a distinct preferred orientation. Despite uniformity of slope and material, the stripes are predominantly aligned parallel to the wind. It is suggested that melting of needle ice by the early morning sun is of only limited importance in the sub-Antarctic owing to the almost continual overcast conditions. The effect of the wind is so great that in exposed situations stripes are formed on horizontal surfaces.  相似文献   

Variability of the Subtropical Front in the Indian Ocean south of Australia     

M.?TomczakEmail author  L.?Pender  S.?Liefrink 《Ocean Dynamics》2004,54(5):506-519

A detailed high resolution survey of a small region (68 × 68 km) of the Subtropical Front south of Australia over a period of 14 days is used to study the interaction between the mixed layer and the permanent frontal structure underneath during summer conditions. The front extends through the mixed layer as a salinity front, while its temperature structure is modified by seasonal warming. Wind-driven movement of the mixed layer combines with the short-time development of indentations and filaments in the front to produce some degree of decoupling between the mixed layer and the underlying structure, and the front is not always found at the same location in and below the mixed layer. Intrusions and parcels of distinct water properties are found just below the mixed layer, produced as a result of the relative movement of the front in and below the mixed layer. These parcels are typically 10 km in width and 10–50 m in depth. Successive surveys of the front with a time separation of 2 days showed that these features persist over at least 1 week. Large scale surveys of the front show that parcels are ubiquitous along the Subtropical Front over a distance of several hundred kilometres. The results suggest that any study aimed at understanding the intricate interaction between the mixed layer and the layers below in oceanic fronts will have to address wind-driven dynamics and frontal dynamics together.This revised version was published online February 2005 with corrections to figures. Unfortunately the figures were reproduced in black and white and in the new version they are in color.  相似文献   

AutoCAD VBA在机场净空测量中的应用   总被引：2，自引：0，他引：2  

戴中东  梁孟华 《北京测绘》2006,(2):53-56

AutoCAD已经广泛的应用在各个行业,同时也是测绘行业软件二次开发的主要平台,本文介绍了用AutoCADVBA实现机场净空测量数据的批量处理,并自动绘制交会点位图。  相似文献   

Frontogenesis, evolution and the time scale of front formation   总被引：1，自引：0，他引：1  

Fang Juan  Wu Rongsheng 《大气科学进展》1998,15(2):233-246

Ｆｒｏｎｔｏｇｅｎｅｓｉｓ,ＥｖｏｌｕｔｉｏｎａｎｄｔｈｅＴｉｍｅＳｃａｌｅｏｆＦｒｏｎｔＦｏｒｍａｔｉｏｎＦａｎｇＪｕａｎ（方娟）ａｎｄＷｕＲｏｎｇｓｈｅｎｇ（伍荣生）ＳｅｖｅｒｅＭｅｓｏｓｃａｌｅｍｅｔｅｏｒｏｌｏｇｉｃａｌＲｅｓｅａｒｃｈＬａｂ...  相似文献   

生态交错带理论及其在海洋生态学中的应用   总被引：6，自引：0，他引：6  

陈尚  朱明远  孟凡  马艳 《地球科学进展》1998,13(5):431-437

在介绍生态交错带理论的基础上,提出开展海洋生态交错带研究。海洋生态交错带定义为相邻海洋生态系统之间的过渡区。海洋生态交错带主要研究内容包括：①建立海洋生态交错带的划分标准;②生态交错带的三维结构;③生态交错带的生态功能;④海洋生态交错带对全球变化的敏感成分和响应机制;⑤海洋生态交错带的生物多样性维持机制;⑥海洋生态交错带与渔场形成的关系。讨论了海洋生态交错带与陆地生态交错带和海洋锋面的不同之处,指出海洋生态交错带研究极有希望成为海洋生态学新的生长点。  相似文献   

Numerical study of the effects of urban heat island on the characteristic features of the sea breeze circulation     

Abhijit Sarkar  R. S. Saraswat  A. Chandrasekar 《Journal of Earth System Science》1998,107(2):127-137

A two-dimensional numerical model is employed to study the effect of the coastal urban heat island on the sea breeze front and the thermal internal boundary layer height. The temperature at the land surface is determined by solving an energy budget equation. The effect of the urban heat island is studied by varying the width of the region and its intensity. During the early afternoon, the presence of the urban heat island enhances the strength of convergence of the sea breeze front and also reduces its inland penetration. The presence of the urban heat island causes increased thermal internal boundary layer height. Larger urban width causes larger vertical velocity and higher thermal internal boundary layer. Stronger convergence and higher thermal internal boundary layer are also obtained in case of larger heat island intensity.  相似文献   

Le jeu fini-Crétacé du front nord-pyrénéen aux environs de Cucugnan (Corbières méridionales,Aude, France)     

André Charrière  Michel Durand-Delga 《Comptes Rendus Geoscience》2004,336(13):1199-1208

The North-Pyrenean Front overthrust in northern direction was particularly active during the Upper Cretaceous, before the Upper Eocene tectonic renewal. Indeed, in the Eastern Pyrenees (Aude), ‘Garumnian’ (continental Upper Cretaceous–Palaeocene) formations lie transgressively upon the North-Pyrenean Triassic (Keuper) formation and upon the Albian beds of the Sub-Pyrenean Cucugnan slice. Relations between the North-Pyrenean Frontal Thrust and, to the northeast, the Corbières Nappe are discussed. To cite this article: A. Charrière, M. Durand-Delga, C. R. Geoscience 336 (2004).  相似文献   

A new formula for front slope recession of berm breakwaters     

T. Lykke Andersen  H.F. Burcharth 《Coastal Engineering》2010

The front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at Aalborg University, Denmark. The results are presented together with a new formula for prediction of the berm recession which is the most important parameter for describing the reshaping. The formula has also been calibrated and validated against model test data from other researchers. The significance of the new design formula is that it predicts berm recession much better than the existing methods, especially in case of more stable structures.  相似文献   

The response of phytoplankton to iron enrichment in Sub-Antarctic HNLCLSi waters: Results from the SAGE experiment     

Jill Peloquin  Julie HallKarl Safi  Walker O. Smith Jr.Simon Wright  Rick van den Enden 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(6):808-823

Areas of high nutrients and low chlorophyll a comprise nearly a third of the world’s oceans, including the equatorial Pacific, the Southern Ocean and the Sub-Arctic Pacific. The SOLAS Sea-Air Gas Exchange (SAGE) experiment was conducted in late summer, 2004, off the east coast of the South Island of New Zealand. The objective was to assess the response of phytoplankton in waters with low iron and silicic acid concentrations to iron enrichment. We monitored the quantum yield of photochemistry (F_v/F_m) with pulse amplitude modulated fluorometry, chlorophyll a, primary productivity, and taxonomic composition. Measurements of F_v/F_m indicated that the phytoplankton within the amended patch were relieved from iron stress (F_v/F_m approached 0.65). Although there was no significant difference between IN and OUT stations at points during the experiment, the eventual enhancement in chlorophyll a and primary productivity was twofold by the end of the 15-day patch occupation. However, no change in particulate carbon or nitrogen pools was detected. Enhancement in primary productivity and chlorophyll a were approximately equal for all phytoplankton size classes, resulting in a stable phytoplankton size distribution. Initial seed stocks of diatoms were extremely low, <1% of the assemblage based on HPLC pigment analysis, and did not respond to iron enrichment. The most dominant groups before and after iron enrichment were type 8 haptophytes and prasinophytes that were associated with ∼75% of chlorophyll a. Twofold enhancement of biomass estimated by flow cytometry was detected only in eukaryotic picoplankton, likely prasinophytes, type 8 haptophytes and/or pelagophytes. These results suggest that factors other than iron, such as silicic acid, light or physical disturbance limited the phytoplankton assemblage during the SAGE experiment. Furthermore, these results suggest that additional iron supply to the Sub-Antarctic under similar seasonal conditions and seed stock will most likely favor phytoplankton <2 ??m. This implies that any iron-mediated gain of fixed carbon will most likely be remineralized in shallow water rather than sink and be sequestered in the deep ocean.  相似文献   

On verification of the new criterion of adiabaticity by numerical simulation of acoustic propagation through the polar front     

Y. Y. Wang  E. C. Shang 《中国海洋大学学报(英文版)》2002,1(1):25-28

To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation (forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is proposed recently (Shang et al., 2001). In this paper, numerical simulation has been conducted for acoustic propagation through the Polar Front to verify the new criterion. Numerical results on the f (frequency)-m (mode number) plan demonstrate that the new criterion works very well for this extremely non-gradual ocean structure.  相似文献