基于小波变换和LSTM神经网络的格陵兰岛近海海域海平面变化预测

海平面变化包含多种不同时间尺度信息，传统的预测方法仅对海平面变化趋势项、周期项进行拟合，难以利用海平面变化的不同时间尺度信号，使得预测精度不高。本文基于深度学习的预测模型，提出一种融合小波变换（wavelet transform，WT）与LSTM （long short-term memory，LSTM）神经网络的海平面异常组合预测模型。首先利用小波分解得到反映海平面变化总体趋势的低频分量和刻画主要细节信息的高频分量；然后通过LSTM神经网络对代表不同时间尺度的各个分量预测和重构，实现海平面变化的非线性预测。基于该模型的海平面变化预测的均方根误差、平均绝对误差和相关系数分别为12.76 mm、9.94 mm和0.937，预测精度均优于LSTM和EEMD-LSTM预测模型，WT-LSTM组合模型对区域海平面变化预测具有较好的应用价值。     

基于灰色多元变权组合预测模型对山东省海水养殖产量预测

为了进一步提高海水养殖产量预测精度, 考虑多因素对海水养殖产量的影响, 文章基于变权组合预测模型, 充分结合长短期记忆(Long Short-Term Memory, LSTM)神经网络预测模型、GM(1, N)预测模型和偏最小二乘回归预测模型等传统统计预测模型的优点, 构建出一种基于灰色多元变权组合预测模型, 并对山东省海水养殖总产量和分类产量进行了预测。实证结果显示, 基于灰色多元变权组合预测模型对山东省海水养殖产量的预测精度高达99.13%, 预测精度显著优于LSTM神经网络等各单项模型, 并能综合于LSTM神经网络、GM(1, N)预测模型和偏最小二乘回归预测模型的优点, 弥补各单项模型的不足, 提高预测精度和可靠性。根据预测结果, 到2025年山东省海水养殖产量仍将保持良好发展, 海水养殖产量将达到579.28×10⁵t, 平均增长速度为3.11%, 而鱼类、甲壳类、贝类、藻类以及海参海水养殖产量将分别达到6.27×10⁵、26.27×10⁵、445.83×10⁵、68.65×10⁵和9.5×10⁵t。     

基于最小二乘与径向基函数神经网络的海平面变化预测

在对海平面变化规律进行深入分析的基础上,应用最小二乘神经网络组合模型对海平面变化趋势进行预测;对卫星测高海平面异常序列中的周期项及线性趋势项利用最小二乘模型进行拟合,残差部分则采用径向基函数神经网络模型进行预测。对中国近海海域卫星测高海平面异常序列的预测表明,连续1个月的预测精度为0.52 cm, 3个月的预测精度为0.65 cm,证明了该组合模型在海平面变化短期预测方面的可靠性,其在海平面变化预测领域具有较高的应用价值。     

1993—2016年中国近海海平面时空变化趋势

区域海平面变化是目前气候变化研究的热点问题.海平面变化具有时间和空间的异质性,分析海平面变化,应充分考虑时间和空间的差异.基于集合经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)、最小二乘法,利用卫星高度计、验潮站数据,分析了1993—2016年间中国近海及周边海域海...     

基于多变量LSTM神经网络模型的PDO指数预测研究

利用1921–2020年的海平面气压、海平面高度、热含量数据以及海冰密集度作为太平洋年代际振荡（Pacific Decadal Oscillation, PDO）指数的预报要素,建立了关于PDO指数时间序列预测的多变量长短期记忆（Long Short Term Memory, LSTM）神经网络模型,对比分析了2011–2020年不同时间序列预测模型的PDO指数预测结果,最后利用多变量LSTM神经网络模型实现了2021–2030年的PDO指数预测。结果显示,多变量LSTM神经网络模型的预测值与观测值经过交叉验证后的平均相关系数和均方根误差分别为0.70和0.62;PDO未来10年将一直处于冷位相,PDO神经网络指数出现两次波动,于2025年出现最小值。相比于其他时间序列预测模型,本文采用的多变量LSTM神经网络模型预测结果误差小、拟合效果好,可以作为一种新型的预测PDO指数的手段。     

中国沿海和近海海平面上升预测

本文利用验潮站观测和卫星高度计数据,以及基于筛选的CMIP6的10个模拟性能较好的地球系统模式结果,对中国海平面的长期变化趋势,以及未来上升幅度进行了分析和预测。结果显示：（1）1960-2021年,中国沿海海平面呈加速上升趋势,上升速率为2.5 mm/a,加速度为0.06 mm/a2;1993-2021年上升速率为4.0 mm/a,高于全球同期3.3 mm/a的上升值。（2）1980-2021年,渤、黄海,东海和南海沿海海平面上升速率分别为3.5 mm/a、3.3 mm/a和3.6 mm/a,渤、黄海和南海沿海海平面上升速率较快,东海偏慢;渤、黄海沿海海平面在20世纪60-70年代上升较慢,80年代之后上升加快。（3）在中等情景（SSP2-4.5）和高情景（SSP5-8.5）下,2050年中国近海海平面将上升0.22 m(0.19～0.28 m)和0.24 m(0.21～0.33 m);到2100年,中国近海海平面将上升0.59 m(0.47～0.80 m)和0.83 m(0.64～1.09 m)。（4）2021-2040年,统计预测的海平面上升中值略接近数值模式低、中和高情景预测值...     

山东半岛近海表层沉积物黏土矿物分布及组合特征

对山东半岛近海表层沉积物进行黏土矿物分析,探讨了研究区黏土矿物分布和组合特征。结果表明,山东半岛近海黏土矿物组合以伊利石-蒙皂石-绿泥石-高岭石型为主,广泛分布在研究区北部、东部和东南外海,为黄河型物质;山东半岛南岸丁字河口及千里岩—石岛外海一带高岭石含量明显增大,黏土矿物组合为高岭石-伊利石-蒙皂石-绿泥石型或伊利石-高岭石-蒙皂石-绿泥石型,为半岛型物质。山东半岛近海黏土矿物分布和组合特征显示了近岸环流对黄河和山东半岛来源物质的搬运和扩散作用。     

基于融合U-Net及ConvLSTM的海面高度异常预报方法研究

海面高度异常是反映海洋环境状况的主要变量之一。本文使用1993—2019年的融合月均海面高度异常数据,建立了基于深度学习的海面高度异常预测神经网络模型,提出了基于融合U型网络(U-Net)和卷积长短记忆网络(ConvLSTM)的中长期海面高度异常预报模型。在研究海域0.25°×0.25°的空间分辨率下,模型测试集预报结果的均方根误差和平均绝对误差分别为0.039 m和0.027 m,均优于全连接LSTM预报模型和ConvLSTM+CNN预报模型,为大中尺度的海面高度异常预报提供了新的方法。     

基于观测和再分析数据的LSTM深度神经网络沿海风速预报应用研究

基于海洋气象历史观测资料和再分析数据等,利用LSTM深度神经网络方法,开展在有监督学习情况下的海面风场短时预报应用研究。以中国近海5个代表站为研究区域,通过气象台站观测数据和ERA-Interim 6 h再分析数据构建数据集。选取21个变量作为预报因子,分别构建两个LSTM深度神经网络框架(OBS_LSTM和ALL_LSTM)。经与2017年WRF模式6 h预报结果对比分析,得出如下结论:构建的两个LSTM风速预报模型可以大幅降低风速预报误差,RMSE分别降低了41.3%和38.8%,MAE平均降低了43.0%和40.0%;风速误差统计和极端大风分析发现,LSTM模型能够抓住地形、短时大风和台风等敏感信息,对于大风过程预报结果明显优于WRF模式;两种LSTM模型对比发现,ALL_LSTM模型风速预报误差最小,具有很好的稳定性和鲁棒性,OBS_LSTM模型应用范围更广泛。     

中国近海海平面变化半经验预测方法研究

由于用数值模式预测未来海平面变化存在很大的不确定性,而统计预测方法又通常不考虑相关物理过程,为此Rahmstorf通过建立海平面变化与全球气温变化的相关模型,提出了一个可行的半经验方法预测全球海平面.本文将Rahmstoff模型应用于中国近海,初步建立了一个在气候变暖背景下中国近海海平面长期变化的预测方法,预测结果表明...     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Evaluation of the Risk of Marine Slope Instability: A Pseudo-3D Approach for Application to Large Areas

This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.