南海中尺度涡温盐异常三维结构   总被引：4，自引：1，他引：3  

谢旭丹  王静  储小青  程旭华 《海洋学报》2018,40(4):1-14

基于1994-2015年海面高度异常数据,采用winding-angle中尺度涡旋探测算法识别出南海范围内共5 899个反气旋涡（AE）和3 792个气旋涡（CE）,结合世界海洋数据集（WOD13）及中国科学院南海海洋研究所（SCSIO）温盐观测数据集,采用基于变分法的客观插值方法,合成了南海及南海各区域中尺度涡的温盐异常三维结构。结果表明,本文采取的插值方式能有效地获得涡旋三维结构,垂向尺度上也与前人研究结果较为一致。在平均状态下,南海AE温盐异常强度明显大于CE,AE正位温异常主体结构深度约440 m,而CE仅在320 m以浅维持涡旋结构;两者最大位温异常均出现在次表层约80 m上下,AE达2.02℃,CE达-1.60℃。盐度异常影响深度约150 m,最大盐度异常出现在50 m深附近,AE达-0.24,CE达0.28,同时由于涡旋在不单调变化的背景盐度场中引起海水下沉（上升）,AE盐度异常结构呈"上负下正"而CE呈"上正下负"式结构。南海各区域合成涡旋的温、盐异常的影响程度并不完全相同,可能与各区域涡旋的生成机制及背景温盐场有关。  相似文献   

Efficacy of magnetically driven temperature-dependent plastic flows in exciting the magnetosphere of CXOU J164710.2-455216     

Chu W. Kwang-Hua 《Astrophysics and Space Science》2018,363(9):184

Using verified transition state theory and quantum plasticity theory we calculate the temperature-dependent shear (strain) rates as well as temperature-dependent (shear) viscosity considering magnetically driven plastic flows in the neutron star (like CXOU J164710.2-455216) crust. Our numerical results which are based on previous works like the critical shear stress as well as the minimum shear (strain) rate of crust (around \(1~\mbox{rad}/\mbox{year}\)) demonstrate that a plastic deformation of the neutron star crust could induced a very slight twist (or shear) in the external magnetic field. We then extend Lander’s calculation of magnetospheric twist to slip-flow cases that will generated currents in the magnetosphere of the magnetar, say, CXOU J164710.2-455216 in Westerlund 1. The latter is believed to be the direct cause of the observed X-ray outburst by Muno et al. once we examine the associated energy scales for corresponding magnetic fields considering the age or history of CXOUJ164710.2-455216 which can be estimated from available measurements or observations. Our results and analysis of relevant energy scales confirm the onset of the soft gamma repeater outburst is controlled by magnetospheric dissipation induced by the plastic motions of the crust.  相似文献   

The Hamburg meteorite fall: Fireball trajectory,orbit, and dynamics     

P. G. Brown  D. Vida  D. E. Moser  M. Granvik  W. J. Koshak  D. Chu  J. Steckloff  A. Licata  S. Hariri  J. Mason  M. Mazur  W. Cooke  Z. Krzeminski 《Meteoritics & planetary science》2019,54(9):2027-2045

The Hamburg (H4) meteorite fell on 17 January 2018 at 01:08 UT approximately 10 km north of Ann Arbor, Michigan. More than two dozen fragments totaling under 1 kg were recovered, primarily from frozen lake surfaces. The fireball initial velocity was 15.83 ± 0.05 km s^?1, based on four independent records showing the fireball above 50 km altitude. The radiant had a zenith angle of 66.14 ± 0.29° and an azimuth of 121.56 ± 1.2°. The resulting low inclination (<1°) Apollo‐type orbit has a large aphelion distance and Tisserand value relative to Jupiter (T_j) of ~3. Two major flares dominate the energy deposition profile, centered at 24.1 and 21.7 km altitude, respectively, under dynamic pressures of 5–7 MPa. The Geostationary Lightning Mapper on the Geostationary Operational Environmental Satellite‐16 also detected the two main flares and their relative timing and peak flux agree with the video‐derived brightness profile. Our preferred total energy for the Hamburg fireball is 2–7 T TNT (8.4–28 × 10⁹ J), which corresponds to a likely initial mass in the range of 60–225 kg or diameter between 0.3 and 0.5 m. Based on the model of Granvik et al. (2018), the meteorite originated in an escape route from the mid to outer asteroid belt. Hamburg is the 14th known H chondrite with an instrumentally derived preatmospheric orbit, half of which have small (<5°) inclinations making connection with (6) Hebe problematic. A definitive parent body consistent with all 14 known H chondrite orbits remains elusive.  相似文献   

基于稀疏贝叶斯学习的水下电场测向方法          下载免费PDF全文

余白石  刁逸帆  钱良  吴云具  邵成  赵治平 《数字海洋与水下攻防》2023,6(5):575-582

水下电场是一种可用于对水下目标进行探测和识别的重要物理场,通过高灵敏度、低自噪声的水下电场探测系统,可实现对水下目标电场信号的远程测向。针对水下目标测向问题,提出了一种基于稀疏贝叶斯学习的水下电场测向方法。该方法采用多个探测单元同时采集处理水下目标辐射的交变电场信号,再通过稀疏贝叶斯学习方法,实现对目标电场信号波达方向的估计,最终估计出目标与探测系统的相对方位。通过湖上试验,验证了该方法的可行性与鲁棒性。相对于常规波束形成算法,在一定测试场景下,该方法对16 Hz频率的正弦波电场信号的测向精度提高了4.8°。  相似文献   

风浪对众包测深数据的精度影响分析          下载免费PDF全文

袁浩  贾帅东  张立华  刘一帆 《海洋测绘》2020,40(6):34-38

针对当前众包测深数据精度难以掌控导致其难以应用的现状,通过构建船舶横摇姿态计算模型,分析了风浪这一重要海洋环境因素对众包测深数据精度的影响程度,得出了众包测深数据的推荐风浪条件和最低要求风浪条件。实验结果表明:①风浪等级增大,各测深点水深测量偏差随之加大,符合《海道测量规范》测深限差要求的测深点数量也随之减少,且在海底倾斜越严重的海域,表现更加明显;②3级风2级浪条件下的众包测深数据可满足限差要求;4级风3级浪时众包测深数据在不同海底倾斜程度下,满足限差要求的数据量不一样;5级以上风4级以上浪在海底倾斜程度超过7.5°时多数测深点不能满足限差要求。  相似文献   

Non-uniform Distributions of Gas Pressure and Coal Permeability in Coalbed Methane Reservoirs Induced by the Loess Plateau Geomorphology: A Case Study in Ordos Basin,China     

Liu  Qingquan  Chu  Peng  Hao  Congmeng  Cheng  Yuanping  Wang  Haifeng  Wang  Liang 《Natural Resources Research》2020,29(3):1639-1655

Natural Resources Research - Coal mine methane (CMM) accumulation and permeability distribution characterization are the bases for a successful CMM drainage design. Before extending degassing...  相似文献   

近惯性内波破碎混合方案对MOM4模式的影响     

吴方华  范植松  楚合涛 《海洋学报》2019,41(3):1-11

风生近惯性内波破碎引起的跨等密度面混合在海洋内部混合中起重要作用。然而其参数化对海洋模式的模拟影响仍有待进一步认识。本文给出的是在模块化海洋模式（MOM）中海洋表面边界层以下引入一个考虑风驱动近惯性内波破碎引起的跨等密度面混合参数化方案的研究工作。模拟结果显示,该方案有效改善MOM4模拟的上层1 000 m以上的温盐偏差,特别是在北太平洋和北大西洋的通风地区。数值试验表明,风生近惯性内波破碎有可能是维持海洋通风过程的重要机制之一,它使得海洋通风区的位温变冷,盐度变淡,整层等位密面加深。维持的通风过程使得北太平洋副极地大涡的影响延伸到副热带大涡。从而模拟的北太平洋中层水源头及其副热带大涡东侧的温盐更接近观测实际。同时,模拟的北大西洋经圈翻转环流强度也更为合理。  相似文献   

水深源数据质量对海岛礁DEM精度影响的定量分析     

刘一帆  贾帅东  姚忠山  孙晓路 《海洋测绘》2019,39(5):5-8

面向海岛礁DEM构建的精度需求,定量分析了水深源数据质量对海岛礁DEM精度的影响规律。梳理了海岛礁DEM构建的基本过程,分析了海岛礁DEM精度的影响因素。在此基础上,以目前普遍执行的有关水深测量的国内外行业规范为依据,统计分析水深源数据的精度、密度等因素对海岛礁DEM精度的影响规律。实验结果表明:采用自适应三角网建模方法所建海岛礁DEM的精度要优于规则三角网DEM的精度;执行我国海道测量规范所获取的水深源数据所建DEM精度,要优于国际海道测量标准一等要求的源数据所建模型精度,略低于特等要求下的源数据所建模型精度。  相似文献   

A new model to estimate significant wave heights with ERS-1/2 scatterometer data   总被引：1，自引：0，他引：1  

过杰  何宜军  申辉  储小青 《中国海洋湖沼学报》2009,27(1):112-116

A new model is proposed to estimate the significant wave heights with ERS-1/2 scatterometer data. The results show that the relationship between wave parameters and radar backscattering cross section is similar to that between wind and the radar backscattering cross section. Therefore, the relationship between significant wave height and the radar backscattering cross section is established with a neural network algorithm, which is, if the average wave period is ≤7s, the root mean square of significant wave...  相似文献   

Construction and characterization of a fosmid library for pathogenic bacterium <Emphasis Type="Italic">Vibrio anguillarum</Emphasis>     

韩一凡  莫照兰  茅云翔  肖鹏  李杰  郝斌  郭东升 《中国海洋湖沼学报》2009,27(3):519-526

Vibrio anguillarum is a common bacterial pathogen in fish.However,little is known about its pathogenic mechanism,in part,because the entire genome has not been completely sequenced.We constructed a fosmid library for V.anguillarum containing 960 clones with an average insert size of 37.7 kb and 8.6-fold genome coverage.We characterized the library by end-sequencing 50 randomly selected clones.This generated 93 sequences with a total length of 57 485 bp covering 1.4% of the whole genome.Of these sequences,58...  相似文献