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ASM-IV仪器在河口近底层悬沙浓度观测分析中的应用研究
周晓妍,戴志军,庞文鸿,李为华
0
(华东师范大学河口海岸学国家重点实验室,上海 200062)
摘要:
近底层悬沙时空变化对于理解河口冲淤变化有着至关重要的作用。然而,长期以来河口近底层水体悬沙浓度的连续变化大都是基于单点观测数据或水样处理获取。基于此,本研究利用光学仪器边界层悬浮物剖面测量仪(Argus Surface Meter IV, ASM-IV)获得长江口南槽近底层进行连续10 d的实测数据,探讨ASM-IV仪器监测悬沙浓度精度的有效性。结果表明:(1)传统仪器布设方法所获取的数据,相对误差高于基于ASM-IV所测误差,在大、中及小潮期间的平均误差值分别为2415%、17.31%和16.18%;越靠近底部河床,相对误差从距底52 cm向下随距底距离的减小而逐渐增大;(2)对于近底层单宽悬沙通量测量结果而言,传统测量仪器布设方法所测量数值一般偏小;(3)大潮时期近底层1 m内的水体悬沙分布均匀,分层不明显;在中、小潮时期,与近底层1 m内平均悬沙浓度相差最大的点皆位于距底20~50 cm附近。因而,近底层悬沙浓度测量时间在大潮时期或越靠近底层,利用ASMIV监测近底层悬沙浓度值更为准确。中、小潮时期利用单点或采集水样测量时,选取0.8H 层水体悬沙浓度代替近底层悬沙浓度较最底部水体悬沙浓度更为准确。
关键词:  海洋水文学  近底层观测  ASM-IV  悬沙浓度  长江口南槽
DOI:10.3969/J.ISSN.2095-4972.2020.02.009
基金项目:科技部重点研发专项政府间合作重点项目资助项目(2018YFE0109900);国家自然科学基金资助项目(41306085,41706093)
Application study of ASM-IV instrument at the near bed 〖JZ〗 suspended sediment concentration measurement in estuary
ZHOU Xiao-yan,DAI Zhi-jun,PANG Wen-hong,LI Wei-hua
(State Key Laboratory of Estuary and Coastal Research, East China Normal University, Shanghai 200062, China)
Abstract:
Temporal and spatial variations of nearbed suspended sediment play a crucial role in understanding the erosion and deposition process of estuarine topography. For a long time, most observed data of the nearbed suspended sediment concentration (SSC) in estuary are acquired based on a single point observation or by water sample treatment,i.e. the traditional layout method of instruments (TLMI) . Here, an accuracy of applying Argus Surface Meter IV (ASM-IV) is studied based on the near bed SSC measurements of South Passage of the Changjiang Estuary in sequent of 20 tidal cycles. The results were drawn as followed: (1) Compared with the SSC from ASMIV, the relative error of measured SSC resulting from TLMI during spring tide period was larger than those at middle and neap tide periods, with corresponding values of 24.15%, 17.31% and 16.28%, respectively, and the relative error by TLMI increased from above 52 cm to the bottom. (2) Compared with those by ASM-IV, the measured suspended sediment flux by TLMI was usually underestimated. (3) During spring tide period, nearbed vertical SSC within 1 meter to the bottom showed a relative uniform distribution, while conspicuous stratification occurred during the middle and neap tide periods. The points of largest difference between measured data by ASMIV and the averaged SSC within 1 meter to the near bottom were located from 20 cm to 50 cm above the bottom. Thereafter, it can be indicated that ASM-IV is more suitable to estimate the nearbed SSC at spring tide or at location closed to the bed. The SSC of 0.8H at the depth profile is more accurate than the bottoms SSC by TLMI during middle or neap tide period.
Key words:  marine hydrology  near-bed observation  ASM-IV  suspended sediment concentration  South Passage of Changjiang Estuary

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