scholarly journals Reconstruction of the track and a simulation of the storm surge associated with the calamitous typhoon affecting the Pearl River Estuary in September 1874

2020 ◽  
Vol 16 (1) ◽  
pp. 51-64
Author(s):  
Hing Yim Mok ◽  
Wing Hong Lui ◽  
Dick Shum Lau ◽  
Wang Chun Woo

Abstract. A typhoon struck the Pearl River Estuary in September 1874 (“Typhoon 1874”), causing extensive damage and claiming thousands of lives in the region during its passage. Like many other historical typhoons, the deadliest impact of the typhoon was its associated storm surge. In this paper, a possible track of the typhoon was reconstructed through an analysis of the historical qualitative and quantitative weather observations in the Philippines, the northern part of the South China Sea, Hong Kong, Macao, and Guangdong recorded in various historical documents. The magnitudes of the associated storm surges and storm tides in Hong Kong and Macao were also quantitatively estimated using storm surge model and analogue astronomical tides based on the reconstructed track. The results indicated that the typhoon could have crossed the Luzon Strait from the western North Pacific and moved across the northeastern part of the South China Sea to strike the Pearl River Estuary more or less as a super typhoon in the early morning on 23 September 1874. The typhoon passed about 60 km south–southwest of Hong Kong and made landfall in Macao, bringing maximum storm tides of around 4.9 m above the Hong Kong Chart Datum (http://www.geodetic.gov.hk/smo/gsi/Data/pdf/explanatorynotes.pdf, last access: 3 January 2020) at the Victoria Harbour in Hong Kong and around 5.4 m above the Macao Chart Datum (https://mosref.dscc.gov.mo/Help/ref/Macaucoord_2009_web_EN_v201702.pdf, last access: 3 January 2020) at Porto Interior (inner harbour) in Macao. Both the maximum storm tide (4.88 m above the Hong Kong Chart Datum) and maximum storm surge (2.83 m) brought by Typhoon 1874 at the Victoria Harbour estimated in this study are higher than all the existing records since the establishment of the Hong Kong Observatory in 1883, including the recent records set by super typhoon Mangkhut on 16 September 2018.

2019 ◽  
Author(s):  
Hing Yim Mok ◽  
Wing Hong Lui ◽  
Dick Shum Lau ◽  
Wang Chun Woo

Abstract. A typhoon struck the Pearl River Estuary in September 1874 (the Typhoon 1874), causing extensive damages and claiming thousands of lives in the region during its passage. Like many other historical typhoons, the deadliest impact of the typhoon was its associated storm surge. In this paper, a possible track of the typhoon was reconstructed by analysis of the historical qualitative and quantitative weather observations in the Philippines, the northern part of the South China Sea, Hong Kong, Macao and Guangdong recorded in various historical documents. The magnitudes of the associated storm surges and storm tides in Hong Kong and Macao were also quantitatively estimated using storm surge model and analogue astronomical tides based on the reconstructed track. The results indicated that the typhoon could have crossed the Luzon Strait from the western North Pacific and moved across the northeastern part of the South China Sea to strike the Pearl River Estuary more or less as a super typhoon in the early morning on 23 September 1874. The typhoon passed about 60 km south-southwest of Hong Kong and made landfall in Macao, bringing maximum storm tides of around 4.9 m above the Hong Kong Chart Datum at the Victoria Harbour in Hong Kong and around 5.4 m above the Macao Chart Datum at Porto Interior (inner harbour) in Macao. Both the maximum storm tide (4.88 m above Hong Kong Chart Datum) and maximum storm surge (2.83 m) brought by Typhoon 1874 at the Victoria Harbour estimated in this study are higher than all the existing records since the establishment of the Hong Kong Observatory in 1883, including the recent records set by super typhoon Mangkhut on 16 September 2018.


2019 ◽  
Author(s):  
Chunjie Wang ◽  
Zhangwei Wang ◽  
Fan Hui ◽  
Xiaoshan Zhang

Abstract. The characteristics of the reactive gaseous mercury (RGM) and particulate mercury (HgP) in the marine boundary layer (MBL) is poorly understood due in part to sparse data from sea and ocean. Gaseous elemental Hg (GEM), RGM and size-fractioned HgP in marine atmosphere, and dissolved gaseous Hg (DGM) in surface seawater were determined in the South China Sea (SCS) during an oceanographic expedition (3–28 September 2015). The mean concentrations of GEM, RGM and HgP2.5 were 1.52 ± 0.32 ng m−3, 6.1 ± 5.8 pg m−3 and 3.2 ± 1.8 pg m−3, respectively. Low GEM level indicated that the SCS suffered less influence from human activities, which could be due to the majority of air masses coming from the open oceans as modeled by backward trajectories. Atmospheric reactive Hg (RGM + HgP2.5) represented less than 1 % of total atmospheric Hg, indicating that atmospheric Hg existed mainly as GEM in the MBL. The GEM and RGM concentrations in the northern SCS were significantly higher than those in the western SCS, and the HgP2.5 and HgP10 levels in the Pearl River Estuary were significantly higher than those in the open waters of the SCS, indicating that the Pearl River Estuary was polluted to some extent. The size distribution of HgP in PM10 was observed to be bi-modal with a higher peak (5.8–9.0 μm) and a lower peak (0.7–1.1 μm), but the coarse modal was the dominant size, especially in the open SCS. There was no significant diurnal variation of GEM and HgP2.5, but we found the RGM concentrations were significantly higher in daytime than in nighttime mainly due to the influence of solar radiation. In the northern SCS, the DGM concentrations in nearshore areas were higher than those in the open sea, but this pattern was not significant in the western SCS. The sea–air exchange fluxes of Hg0 in the SCS varied from 0.40 to 12.71 ng m−2 h−1 with a mean value of 4.99 ± 3.32 ng m−2  h−1. The annual emission flux of Hg0 from the SCS to the atmosphere was estimated to be 159.6 tons yr−1, accounting for about 5.54 % of the global Hg0 oceanic evasion though the SCS only represents 1.0 % of the global ocean area. Additionally, the annual dry deposition flux of atmospheric reactive Hg represented more than 18 % of the annual evasion flux of Hg0, and therefore the dry deposition of atmospheric reactive Hg was an important pathway for the input of atmospheric Hg to the SCS.


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