Journal of Tropical Oceanography >
Surface suspended sediment distribution of Pearl River estuary under tropical storms with different wind and river discharge forcing
Copy editor: LIN Qiang
Received date: 2018-09-10
Request revised date: 2018-12-20
Online published: 2019-06-17
Supported by
National Natural Science Foundation of China(41106015)
National Key Research and Development Program of China(2016YFC0402600)
Copyright
In this study, the data of tropical storms, CFSR gridded wind during 1949~2014, and Pearl River discharge were used to analyze wind forcing and runoff forcing on the Pearl River estuary (PRE) under tropical storm. The results show that the wind and runoff forcing varied with location and strength of the storm, and can be classified into four types: storm I with medium wind and runoff forcing on PRE, storm II with medium wind and high runoff forcing, storm III with strong wind and medium wind, and storm IV with strong wind and high runoff forcing. According to the selected moderate-resolution imaging spectroradiometer (MODIS) imaging with fine and no cloudy during tropical storms in South China, existing empirical formula between the water reflectance of MODIS band 1 and suspended sediment concentration (SSC) was used to retrieve the surface SSC in the PRE during storms, and the corresponding spatial diffusion of SSC was studied. We find that under four types of storms with different wind and runoff forcing, the responses of SSC in the PRE were different. The SSC was low under storm I, and suspended sediment diffusion was mostly controlled by tidal current. Under storm II, the higher SSC was shown in the Modaomen Estuary shoal and Lingdingyang west shoal than the other areas, which was mostly transported southwesterly. Under storm III, the distribution and diffusion of suspended sediment were influenced by the dominant storm wind, so that under strong NE wind, Lingdingyang west shoal sediment was resuspended by relatively larger waves for the largest wind fetch in the Lingdingyang estuary, higher SSC was presented and transported to the southwest under longshore current. The response of the PRE to storm IV was that the water body was muddy and the SSC was high in the whole PRE than under normal condition; and under southerly storm wind, the high SSC was diffused to the east
OU Suying . Surface suspended sediment distribution of Pearl River estuary under tropical storms with different wind and river discharge forcing[J]. Journal of Tropical Oceanography, 2019 , 38(3) : 22 -31 . DOI: 10.11978/2018092
表1 热带风暴前后的MODIS影像及环境条件Tab. 1 MODIS images and corresponding environmental conditions during tropical storms |
影像日期 | 风暴名 | 潮汐 | 水沙强迫类型 | 主导风 | 珠江入海最大流量/(m3·s-1) | |
---|---|---|---|---|---|---|
最大风速/(m·s-1) | 风向 | |||||
2005-08-03 | 天鹰 | 落潮 | Ⅰ | 9.3 | E | 9262 |
2006-08-14 | 宝霞 | 涨潮 | Ⅱ | 8.9 | ENE | 39600 |
2006-05-14 | 珍珠 | 落潮 | Ⅲ | 20.8 | ENE | 14600 |
2006-07-21 | 碧利斯 | 落潮 | Ⅳ | 16.5 | SSW | 57100 |
2008-06-20 | 风神 | 落潮 | Ⅳ | 14.2 | SSW | 57600 |
图5 天鹰台风后2005年8月1—3日的驱动风玫瑰图(a)及3日中风中水沙驱动下的珠江口落潮悬沙分布(b)Q为珠江流量,下同 Fig. 5 The spatial distribution of surface SSC (b) in PRE under Typhoon Washi with dominated SW wind (a) at ebb tide on August 3, 2005, where the wind data and Pearl River discharge Q of three days before the imaging (b) were used |
图6 宝霞台风后2006年8月14日中风高水沙驱动下珠江口表层涨潮悬沙分布a为12—14日的驱动风玫瑰图, b为悬沙分布, 箭头代表八大口门水沙输运方向及分水分沙强度的差异 Fig. 6 The spatial distribution of surface SSC (b) in PRE after Typhoon Bopha with dominated E-ENE wind (a) at flood tide on August 14, 2006, where the wind and Pearl River discharge data of three days before the imaging (b) were used |
图7 珍珠台风期间2006年5月12—14日的驱动风玫瑰图(a)及14日强风中水沙驱动下的珠江口表层落潮悬沙含量分布(b)Fig. 7 The spatial distribution of surface SSC (b) in PRE before Typhoon Chanchu with dominated NE-ENE wind (a) at ebb tide on May 14, 2006, where the wind and Pearl River discharge data of three days before the imaging (b) were used |
The authors have declared that no competing interests exist.
作者已声明无竞争性利益关系。
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