Radar studies of the distribution of the formation zones of the first radar echo of hail clouds

The results of studying the regions of hail-cell formation in the North Caucasus are considered. The optimal range of the underlying surface heights for their generation is determined based on an analysis of 392 hail cells. It is shown that the majority of hail cells are formed in the zone where the heights of the underlying surface vary from 900 to 2400 m. The most favorable conditions for the formation of hail clouds are recorded in the northern slopes of the Skalistyi (Rocky) ridge. This region accumulates the main maxima of the frequency of first radar echo recording. The second group of the frequency maxima is located over the Pastbishchnyi (Pasturable) and the Lesistyi (Woody) ridges. The generalized scheme for the region under study is constructed of three zones of generation of the first radar echo of the hail cells. It is shown that approximately 70% of hail clouds are formed over submontane and mountainous regions in the central North Caucasus (zones 2 and 3). The directions of motion of hail cells are quantified for each identified zone.     

Mathematical simulation of the bio-optical state of water in application to the passive probing problem

The method of bio-optical modelling of seawater is discussed in application to the passive remote sensing of an ocean within the optical wavelength range. The model implies the presence of two hydrobiological characteristics in the algorithm for the spectral composition of upward radiation, namely the phytoplankton pigment concentration and the total particulate organic matter. The method has been thoroughly tested. The data provided byin situ measurements in the areas accommodating waters of different types (from Case 1 and Case 2) and the modelling results, with the errors being considered, are in good agreement.Translated by Vladimir A. Puchkin.     

基于PSR模型的珠江口海域富营养化特征与评价

本研究依据2020年4月(春季)和2020年10月(秋季)珠江口海域的调查数据,根据“压力-状态-响应”(PSR)模型对珠江口海域进行富营养化状况评价,并通过主成分分析以及相关性分析来说明各环境因子对珠江口富营养化的影响。结果表明：在“优、良、中、差、劣”5个富营养化等级中,珠江口PSR综合评价等级为“差”等级,近几年内变化趋于稳定。有机污染物与营养盐对珠江口富营养化的影响较大,其次为叶绿素a和溶解氧。珠江口营养盐与盐度呈显著负相关,与叶绿素a呈显著正相关。周边城市的陆源排放输入是导致珠江口富营养化的主要因素,河口稀释混合作用以及浮游植物对珠江口的富营养化程度有影响。     

近岸波浪破碎区不规则波浪的数值模拟

基于近岸不规则波浪传播的抛物型缓坡方程和两类波浪破碎能量损耗因子,对近岸波浪破碎区不规则波浪的波高分布进行了数值模拟,并结合实验结果对数值模拟结果进行了验证分析,结果表明采用两类波浪破碎能量损耗因子所模拟的破碎区波高与实测值均吻合良好,波浪破碎能量损耗因子及波浪破碎指标对破碎区波浪波高分布影响较明显。     

威海南部近岸海域表层海水化学要素时空变化及富营养化研究

为了客观评价威海南部近岸海域海水化学要素时空分布及富营养化状况,分别于2013年春季、夏季及秋季3个航次进行表层海水水质调查.样品分析表明:调查海域表层海水水质符合二类水质标准,其中DO含量为6.040~7.880 mg/dm~3,DIN含量为0.156~0.252 mg/dm~3,DIP含量为0.006~0.018 mg/dm~3,COD含量为0.670~1.730 mg/dm~3.DO呈现从海岸线向外海逐渐升高的趋势,DIN、DIP及COD均呈现从海岸线向外海逐渐降低的趋势.营养盐的时空变化趋势受外源污染物的输入、养殖生物的排泄输入、浮游植物及大型海藻生长的共同影响.N/P分析表明春季变化最大,夏季次之,秋季变化幅度最小,3个季节中均为磷限制,可以通过控制磷酸盐的输入控制浮游植物的生长,从而避免赤潮的发生.富营养化状态指数分析表明调查海域的富营养化状态指数从海岸向外海逐渐降低,其中2号站(靖海湾湾口)、11号站(乳山湾湾口)及12号站(乳山湾湾口)受外源污染物的影响较大,呈现富营养化.调查表明3个季节的富营养化状态指数逐渐升高,与外源污染物的输入加大及养殖活动的逐渐频繁密切相关.     

长江口甲藻孢囊与水体富营养化和厄尔尼诺指数关系研究

甲藻孢囊是一种可用于追溯环境变化历史的生物微化石,如指示水体富营养化和气候变化,但是如何指示水体富营养化存在争议,并且如何区分甲藻孢囊中的水体富营养化信号和气候变化信号也是一个科学难题。为了研究这两个科学问题,我们利用长江口海域受到水体富营养化和厄尔尼诺事件双重影响的特点,在该海域不同位置采集了4根沉积柱,分析了其中的甲藻孢囊。结果显示,长江口海域水体富营养化会引起总甲藻孢囊以及产麻痹性贝毒甲藻孢囊丰度上升,并且导致异养型和自养型甲藻孢囊的比率下降,这说明引起长江口海域富营养化主要原因还是以氮、磷、钾为主导的农业和生活污水。受长江冲淡水流影响,这种富营养化信号在近处相对较弱;中间处信号明显;远处信号几乎未见。同时入海口近处高沉积速率沉积柱样的分析结果显示,甲藻孢囊丰度存在季节性的变化规律,其中以冬季甲藻孢囊丰度最低,推测低温起了主导作用。而厄尔尼诺气候事件可以通过影响陆地径流从而改变陆源营养盐的输入来改变甲藻孢囊丰度,反映在沉积柱中的信息即为甲藻孢囊丰度峰谷值的出现。该信号也随距离入海口的远近不同而不同：近处受水流突然增大或减弱导致甲藻孢囊丰度谷值和峰值出现;中间处水流与甲藻孢囊丰度峰谷值重叠且信号较强;远处丰度峰值信号明显但主导因素多样化。这些结果对该海域环境演变历史重建,赤潮发生历史和厄尔尼诺现象研究都具有十分重要的科学意义。     

Deep water clastic reservoirs in the Gulf of Mexico: A depositional model

A conceptional model has been developed relating the deposition of thick sand sequences in deep water regions of the Gulf of Mexico to episodes of high volume Mississippi River discharge. In accordance with the model, coarse sand units are deposited by turbidity currents as submarine fans on the lower slope and in the deep basin during periods of rapid glacial melting. These sands are predicted to be more extensive and cleaner than those deposited under glacial and interglacial conditions. Evidence supporting this interpretation is provided from projections of the high rates of river discharge and sediment transportation at the end of the Wisconsin glacial epoch.     

On the problem of local tsunamis and possibilities of their warning

At present, the problem of predicting tsunamis with source earthquakes near the shoreline remains practically unresolved. It is shown that, in the Pacific region, 87% of tsunamigenous earthquake epicenters are located closer than 100 km to the shoreline and 67% are closer than 50 km. For a more detailed analysis, the area of the Pacific Ocean was divided into ten subregions: Kamchatka, the Kuril Islands, Japan, Indonesia, Australia and Oceania, South and Central America, Alaska, and the Aleutian Islands. Each subregion was analyzed individually. All the earthquakes from 1950 to 2003 with Ms >= 6.0 causing tsunamis with intensities I > 0 were processed. The ITDB/PAC 2004 database was used as the data source. For each subregion, mean and minimal travel times were calculated. The minimal travel times for all the regions except for a single one are less than 10 min. It is shown that, in the near earthquake zone, no tsunami alert based sea-level gauge data is possible. One probable solution could be based on detecting hydroacoustic signals that precede strong earthquakes in the near-shore zone.     

广东沿海红树林区水质变化特征与富营养状态评估

调查了广东红树林区水质的时空变化, 分别采集了红树林区表层水体水样旱季30个样点(2017年10月至2018年1月)和湿季20个样点(2018年7月至8月)进行分析。利用单一营养状态指数(TSI Chl a)评价红树林水质特征和营养状态, 评价标准: 050为富营养, >70为高营养。红树林区环境参数的时空变化为: 盐度(2.15‰~27.14‰)、pH (6.18~8.65)、电导率(10.87~90.52µs·cm^-1)、浊度(0.0975~21.61FTU)、硝酸盐(0~127.2mg·L^-1)、亚硝酸盐(0~12.0mg·L^-1)、磷酸盐(0~34.5mg·L^-1)、硅酸盐(1.22~2.88mg·L^-1)和叶绿素a (0.19~38.08mg·m^-3)。聚类分析表明, 丰水期横跨雷州半岛右侧至广东沿海东部的水质相对较好, 而左侧则处于中营养化状态。同时, 在枯水期, 红树林区水质较差, 从雷州半岛周围的高中营养化状态, 到广东沿海东部的富营养化状态。主成分分析表明, 营养盐、盐度、pH、电导率(electrical conductivity, EC)和浊度对红树林区水质状况贡献显著, 进而影响红树林生态系统中藻类群落的变化。     

Two-position quasi-mirror radar of the sea surface: Principles of microwave scattering and possibilities of solving Oceanology problems from space

Using available wind wave spectra data, we consider the applicability conditions of the tangent plane (Kirchhoff) method and the small perturbations and diffusion (Rayleigh) method to construct microwave diagrams of sea surface scattering (quasi-mirror forward scattering). We take into account the peculiarities of Earth sensing from orbit, the closeness of viewing of a mirror point to the Brewster angle, and the possibility of simultaneous formation of wide-capture radar images for the coaxial and collinear polarization components of a reflected signal. It is concluded that, taking into account the approximations made, it is possible to creat panorama small- and mesoscale images of the field of wind wave slopes for a coverage area on the order of 2000 km. Then, based on earlier engineering design studies, we present three possible modifications of “tandem” space radar designed to efficiently solve certain oceanological and applied problems.     

On the performance of a shipborne current mapping HF radar

High-frequency (HF) radars have been developed to map surface currents offshore by means of land-based stations. Presently available radar systems use frequencies between 25 and 30 MHz and allow a spatial resolution of 1 km and ranges of up to 50 km. This paper reports on the experience with a shipborne radar and discusses problems which arise for the azimuthal resolution on a metal ship, the correction for the ship's speed, and limitations due to pitch-and-roll motions. Current measurements during cruises to the North Atlantic are presented. It has been found that, with the support of the satellite-supported Global Positioning System, the shipborne HF radar can measure surface current velocities with an accuracy of some 5 cm·s^-1     

On the synthetic aperture radar imaging of ocean surface waves

A process of synthetic aperture radar imaging of ocean surface waves is considered on the basis of the two-scale model of microwave scattering by a disturbed sea surface. Analytical expressions are obtained to relate characteristics of a large-scale wave image, averaged over an ensemble of realizations of the small-scale ripple, with the wave, radar, and viewing scheme as parameters. It is shown that the wave image would be defocused as an image of a target moving in the along-track direction with a speed equal to a half of the wave phase speed projection on the line of flight. The defocusing magnitude was measured experimentally for the ocean swells images, obtained with an airborneS-band radar, and the results are found to be in satisfactory agreement with the model prediction.     

胶州湾海水富营养化水平评价

根据2002年4个季度调查资料,选择活性磷酸盐、溶解无机氮、溶解氧、化学耗氧量、叶绿素a为评价因子,利用模糊综合评价模型对胶州湾的营养水平及动态变化进行了评价。结果表明,无论是季节变化还是年度总评胶州湾大部分水域的N、P浓度偏高,处于中度营养和富营养化水平,东部、东北部和西北部水域富营养化明显。     

泉州湾表层水主要化学要素含量和富营养化指数的时空变化特征

根据泉州湾2010年4个航次的现场调查资料,分析泉州湾表层海水中化学需氧量、无机氮、活性磷酸盐含量的季节变化特征,应用海湾富营养化评价模式对泉州湾海域海水富营养化状态进行评价,得出秋季和冬季富营养化指数（17.85和18.32）相对较高,夏季和春季富营养化指数（3.02和5.89）相对较低,与无机氮、活性磷酸盐含量的季节变化特征相似.根据近20 a泉州湾海域历史监测数据得出富营养化指数年际变化特征呈现先缓慢升高,后下降,最后又升高的趋势,与无机氮、活性磷酸盐的年均含量变化特征基本相似,近几年来富营养化指数（14.57）急剧增大,表明泉州湾海水富营养化程度非常严重.泉州湾海水富营养化指数平面分布特征总体上呈现由湾口向晋江入海口、后渚附近海域逐渐递增的趋势,与无机氮含量平面分布特征一致,与活性磷酸盐含量平面分布特征相似.     

On the accuracy of current measurements by means of HF radar

The accuracy of surface current velocities measured by high-frequency (HF) radar is investigated. Data from the two radar systems of the University of Hamburg, CODAR (Coastal Radar) and WERA (Wellen Radar), are compared with in situ data. In one experiment, CODAR and a near-surface current meter were operated simultaneously over a 19-day period. In addition, WERA was operated for 6 days during that period. In the other experiment, WERA and a bottom-mounted current meter were operated simultaneously over a 35-day period. Both radars use frequencies of about 30 MHz where backscattering is due to ocean waves of 5 m wavelength. The influence of the orbital motion of underlying longer waves on radial velocity errors is investigated. In accordance with theory, the measured standard deviations of HF-measured current velocities depend on the sea state. Depending on the sea state, estimated errors range from 3 to 10 cm·s^-1 and explain only part of the rms difference of 10-20 cm·s^-1 found between HF and in situ current measurements. The rest is assumed to be due the differences of the quantities measured, e.g., the spatial averaging     

通过水体置换降低水库富营养化风险：长江口青草沙水库案例研究

城市淡水系统的富营养化风险是世界范围内普遍关注的问题。多种物理、生物和化学技术手段被应用到富营养化湖库的治理当中,以期抑制水体的富营养化程度和藻类生物量。经证实,在未有效降低营养盐来源的情况下,这些手段的效果有限。而在发展中国家,控制营养盐来源可能需要花费数十年的时间。本研究旨在分析某一高营养盐负荷的沿海水库的富营养化和藻类水华风险,以期确认通过水利调度来抑制水库富营养化状态的可行性。该案例水库为位于长江口的青草沙水库。该水库2009至2012年期间的库内五个点位的水质数据被用于进行案例分析。水质指标包括水温、透明度、溶解氧、总氮、总磷和浮游植物叶绿素a。该水库的建设期为2009年4月至2010年10月,期间水库未曾与长江口发生水体交换。该水库的试运营期为2010年10月至2011年1月,正式运营期为2011年1月至今。在运营期间,库内与长江口的水体交换逐步上升。综合营养状态指数（TLI）被用于评估该水库的营养状态变化情况,该指数是通过数个代表性水质指标计算得到。库区的TLI指数峰值在2009年夏季可达51,在2011年夏季可达55,超过TLI指数的富营养化阈值50。TLI的谷值32出现在2010年的夏季。水质观测期的其他时段的TLI指数均可保持在50以下。以上分析结果表明：水库在2009年和2011年夏季由于过量的营养盐负荷和藻类水华迅速恶化到富营养化状态。水库在2010年和2012年均未出现富营养化状态和藻类水华,这是由于2010年期间水库缺少营养盐输入,2012年期间水库调度充分地置换了库区水体。库区水质指标的时空变化均通过文中的观测资料和数据分析进行展示。经分析表明,通过潮汐涨落来充分置换库区水体的水库调度手段是一个极为经济有效的抑制高营养盐水体富营养化和藻类水华的工程手段。     

Preliminary study of rain effects on radar scattering from water surfaces

Preliminary wave-tank results indicate that radar scatter from water surfaces is severely affected by rain at low but not at high wind speeds. The effect is governed by both the rain rate and droplet size. A simple experiment to check this phenomenon is described.     

水淹层测井识别方法研究及效果验证

油田在长期注水开发过程中,不仅储层孔隙空间结构发生变化,而且储层含油饱和度也发生了变化,形成了水淹层。水淹层的测井解释是油田开发的一个难题,经研究分析表明,油层水淹前后的测井响应特征不同,且从宏观沉积特征看,不同的沉积微相类型,其储层物性在水淹前后变化量也不同。据此,可以通过单井常规测井资料解释,或通过一些特殊测井资料与常规测井资料的综合分析来解释和识别水淹层,并依据对子井测井曲线特征研究、生产动态资料研究、密闭取心资料分析、沉积微相划分及多井综合评价等一系列技术对解释结果进行有效性验证,从而找到水淹层电性特征与含油饱和度及沉积特征的关系,达到准确解释水淹层的目的。     

浅地层剖面探测综述

海洋地球物理技术在海洋地质调查中起重要作用,其中浅地层剖面探测因其成本低、效率高,在海洋地质调查研究中具有广阔的应用前景.浅地层剖面探测是利用声波在水中和水下沉积物内传播和反射的特性来探测海底浅部地层结构和构造的.本文阐述了浅地层剖面仪发展历程,针对浅地层剖面探测,分析了其主要影响因素和压制方法,并对主要剖面声图类型及...     

富营养化滩涂生物修复研究进展

近年来,随着海水富营养化加剧,滩涂沉积物多项重要理化参数也随之恶化,进而导致滩涂底质生境退化,表现出较为明显的富营养化趋势。为改善和恢复滩涂沉积物的生态环境,国内外学者进行了较多的生物境修复探索研究工作。作者概述了滩涂富营养化的现状及原因,各种滩涂生物修复技术的原理、特点及其修复效果,分析了各类生境修复技术的优缺点。同时,就滩涂生境修复技术在滩涂修复和海洋环境保护领域今后的研究重点进行了展望。