洋面冷锋的三维数值模拟──潜热释放对冷锋结构的影响

通过比较一次洋面冷锋过程的干、湿三维模拟结果，揭示潜热释放对冷锋结构的影响。结果表明：由于潜热释放的作用，冷锋区的温度梯度和风矢量的气旋性切变大大地加强了，冷锋附近的涡度场和垂直速度场呈现出更多的更加紧密的中尺度结构；锋面非地转直接环流在湿模拟中比在干模拟中发展得更加充分并且具有更高的组织性；潜热加热倾向于增加锋面环流的强度，尤其是其上升支的强度。研究表明，潜热释放过程是形成冷锋前沿上方低层大气中狭窄强上升气流区的关键因素之一。     

Basement and cover relations on the northern margin of the Amadeus Basin, central Australia

A major, linear, west-trending deformed zone (The Redbank Zone), 350 km long and up to 20 km wide, can be identified in the Arunta Block immediately north of the Amadeus Basin. The marked linearity of this zone and of the coincident gravity anomaly probably result from thrust-fault movement during the Carboniferous Alice Springs Orogeny. However, in the Ormiston area, there is evidence that the zone originated prior to 1070 m.y. and acted as a major crustal feature controlling the later orogenic event.The Alice Springs Orogeny affected the overlying Proterozoic and Lower Palaeozoic cover rocks as well as the Arunta Block basement. During the orogeny, steep north-dipping thrusts within the Redbank Zone were reactivated causing uplift to the north. These faults penetrated the Heavitree Quartzite—the basal unit of the cover sequence—to drive wedges of basement, with attached veneers of Heavitree Quartzite, for up to 20 km southward within the overlying Bitter Springs Formation. The nappes did not reach the surface or penetrate formations above the Bitter Springs. Accompanying nappe emplacement the Basin to the south rapidly deepened to receive a thick wedge of synorogenic molasse sediments.Gravity, sedimentary and structural features combine to suggest that the Alice Springs orogeny movements reached their maximum on the central part of the northern margin of the Amadeus Basin, in the Ormiston area.     

Interactions of biogenic opal,sediment and seawater in the Central Equatorial Pacific

The solution rate of biogenic opal in near-surface sediments in the Central Equatorial Pacific is three to eight orders of magnitude lower than similar acid-cleaned samples. Iron, magnesium and calcium aluminosilicates may be the minerals which are forming on the surface of the opal and reducing its solution rate. The scale height of the system studied suggests that diffusive and not advective processes are primarily responsible for the removal of dissolved silica in sediments. Solution budget calculations for this area suggest that 90–99 per cent of the biogenic opal produced in surface waters dissolves before reaching the sediment-water interface; an additional amount dissolves within the sediment and diffuses into bottom waters leaving 0.05–0.15 per cent of the original amount of opal produced by organisms in the sedimentary record. The relative solution potential of the upper 1000 m of the water column varies by more than an order of magnitude from the Antarctic to Equator and may have a pronounced effect on the accumulation rate of biogenic opal in underlying sediments.     

Time and frequency domains response analyses of April 2015 Greece’s earthquake in the Nile Delta based on GNSS-PPP

Earthquake response characteristic and sensitivity of 1-Hz Global Navigation Satellite System - precise point positioning (GNSS-PPP) for a seismic response in time and frequency domains are the main objectives of this study. The Delta and Cairo areas, Egypt, experiencing the shock of the Greece earthquake occurring on April 16, 2015 (18:50 hours), is presented in this study. The results of this study reveal that the seismic wave effect is very small and can be neglected inside the Delta region and the strong motion occurred in an upward direction for the whole monitoring area. Furthermore, the time-frequency analysis illustrates the ability of the time and frequency domains to use and analyze the surface motion based on a 1-Hz sampling frequency and to detect the small- and high-strength motions of seismic waves.     

Spatial and Temporal Variations in <Emphasis Type="Italic">Pyrodinium bahamense</Emphasis> Cyst Concentrations in the Sediments of Bioluminescent Mangrove Lagoon,St. Croix,USVI

Mangrove Lagoon, located on the island of St. Croix, US Virgin Islands (USVI), is one of few actively bioluminescent lagoons in a location experiencing significant anthropogenic impacts. The bioluminescence is due to an abundance of the dinoflagellate Pyrodinium bahamense in the water column. We recovered surface sediments and sediment cores from Mangrove Lagoon to analyze the spatial distribution and temporal variability of P. bahamense cysts in this system. Surface sediment P. bahamense cyst concentrations ranged from 0 to 466 cysts g^?1 dry sediment, with higher abundances associated with elevated surface water nutrient concentrations and a mixed terrestrial–marine organic matter source regime. In combination with available bioassay data, we hypothesize that phytoplankton utilize nutrients rapidly and subsequent decay of organic matter makes nutrients available for dinoflagellates at the sediment–water interface in the eastern and northern quadrants of the lagoon. However, the nutrients are rapidly exhausted during counterclockwise lagoon circulation resulting in the decline of primary productivity and dinoflagellate abundance in the western quadrants. Downcore profiles suggest that P. bahamense blooms have been occurring for decades, declining in recent years. No cysts were present in sediments predating dredging activities of the 1960s that created Mangrove Lagoon. Recent reductions in cyst abundance may be the result of limited primary productivity caused by restricted water exchange with Salt River Bay due to shallowing of a sill at the mouth of the lagoon. This research highlights the need for more comprehensive geochemical and fossil analyses to better understand long-term ecological variability and inform conservation efforts of these unique habitats.     

直脉蝎蛉科(昆虫纲长翅目) 3个异物同名和 1个种的修正

1996 年,张海春发表《新疆准噶尔盆地中生代直脉科(昆虫纲)昆虫化石》一文[古生物学报,35(4)：442-494],共有5个新种和5个老种,其中1个老种定为Mesopanorpa obscura(Martynov, 1927),包含3 个标本：① NIGP126378(92-T-22/K1),② NIGP126377(58SK15/K3),③ NIGP126376(92-T-22/K3)。另1个标本NIGP126379(93-HE-2K1,2)定为Protorthophlebia latipennis Tillyard, 1933。笔者在研究长翅目化石的过程中,发现张的4个标本系异物同名,前3 个标本即：① NIGP126378号标本勉强修订为1个近似种P. (Protorthophlebia) aff. obscura (Martynov,1925) Martynov,1927;② NIGP126377号标本修订为新名种Protorthophlebia(Protorthophlebia) badouwanica nom. nov.;③ NIGP126376号标本, 由于这个标本脉序结构与副蝎蛉科 Parachoristidae Tillyard, 1937的脉序特征相同,已被修订为另一个属、种Junggarochorista tuzigouensis Hong, 2009[13],已转移归入该科。④另1个标本NIGP126379号标本被修订为新名种 P.(Protorthophlebia) karamayiensis nom. nov.。上述被修订后的新名属、种在本文中作了必要的重新描述。修订的标本,都根据张海春论文中原标本照片显示的脉纹特征和文字描述。所修订学名的原标本均按原文的记录保存在中国科学院南京地质古生物研究所。     

Indications of an extreme event deposits along the west coast of India: evidences from GPR investigations

The ground-penetrating radar (GPR) was used to trace the subsurface details in the Palshet coastal zone (Maharashtra) as it exhibits an interesting array of geomorphological features. Furthermore, our main goal was to identify and locate features that might have formed during a reported extreme event and its effects on the flow of the nearby Sundri River. Two profiles (8 and 4 m depth) were collected across the beach and along the backshore, respectively. While the 8-m depth profile (west to east; across the beach) indicates a series of coastline regression in this area, the 4-m depth profile along the coastline (north to south) in the backshore zone reveals two significant incidents viz., (1) stages of development of the paleo-channels that indicate the migration of the Sundri River towards south and (2) huge sediment deposits up to 2.5-m thick in the backshore area. The erosional relict surface (~2.5 m depth) was traced along with various spells of sediments that perhaps occurred due to an extreme event. Sand samples were collected from two trial pits along the GPR profiles to understand the sedimentology and mineralogy in the backshore area. These data together with beach profiles and geomorphological maps suggest that the sands were deposited by an extreme event perhaps during the 1854 cyclonic storm. The sands were trapped in suitable geomorphological sites along the Palshet coast and these sand deposits of about 2.5 m thickness forced the River Sundri to shift its course towards the south. This new revelation facilitates a further study that could focus on the nearby coastal areas to document such extreme event deposits and their influence on the geomorphic set-up.     

A Gill Twin Propeller-Vane Anemometer for Flux Measurements During Moderate and Strong Winds

A wind velocity measuring system based on the Gill propeller anemometer is described. A method of calculating the vertical component, which allows for the non-cosine response and avoids the region of stall and nonlinear operation, is presented. A summary of the possible errors in Reynolds stress and drag coefficient estimates is given. A method of establishing the distance constant using field observations is presented. Finally, some preliminary results and some intercomparisons with otheranemometers are described briefly.     

Changes in Arctic clouds during intervals of rapid sea ice loss

We investigate the behavior of clouds during rapid sea ice loss events (RILEs) in the Arctic, as simulated by multiple ensemble projections of the 21st century in the Community Climate System Model (CCSM3). Trends in cloud properties and sea ice coverage during RILEs are compared with their secular trends between 2000 and 2049 during summer, autumn, and winter. The results suggest that clouds promote abrupt Arctic climate change during RILEs through increased (decreased) cloudiness in autumn (summer) relative to the changes over the first half of the 21st century. The trends in cloud characteristics (cloud amount, water content, and radiative forcing) during RILEs are most strongly and consistently an amplifying effect during autumn, the season in which RILEs account for the majority of the secular trends. The total cloud trends in every season are primarily due to low clouds, which show a more robust response than middle and high clouds across RILEs. Lead-lag correlations of monthly sea ice concentration and cloud cover during autumn reveal that the relationship between less ice and more clouds is enhanced during RILEs, but there is no evidence that either variable is leading the other. Given that Arctic cloud projections in CCSM3 are similar to those from other state-of-the-art GCMs and that observations show increased autumn cloudiness associated with the extreme 2007 and 2008 sea ice minima, this study suggests that the rapidly declining Arctic sea ice will be accentuated by changes in polar clouds.