THE VERTICAL LAND MOTION OF TIDE GAUGE AND ABSOLUTE SEA LEVEL RISE IN BOHAI SEA

D Zhou,W Sun,Y Fu,X Zhou

doi:10.5194/isprs-annals-iv-2-w5-601-2019

Abstract

Abstract. The ground vertical movement of the tide gauges around the Bohai sea was firstly analyzed by using the observation data from 2009 to 2017 of the nine co-located GNSS stations. It was found that the change rate of ground vertical motion of four stations was in the same order of magnitude as the sea level change. In particular, the land subsidence rate of BTGU station reaches 11.47 mm/yr, which should be paid special attention to in the analysis of sea level change. Then combined with long-term tide gauges and the satellite altimetry results, the sea level changes in the Bohai sea and adjacent waters from 1993 to 2012 were analyzed. The relative and absolute sea level rise rates of the sea area are 3.81 mm/yr and 3.61 mm/yr, respectively, both are higher than the global average rate of change. At the same time, it is found that the vertical land motion of tide gauge stations is the main factor causing regional differences in relative sea level changes.

Highlights

In the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) in 2013, the global sea level rose by 0.19m from 1901 to 2010, with an average sea level rise rate of 1.7mm/a
The vertical land motion of 9 tide gauges around the Bohai Sea is analyzed by using the continuous observation data of co-located GNSS stations in the past nine years
GNSS monitoring results show that the vertical land motion of BXCS, BLHT, BBYQ, BTGU, BLKO, BCST and other tide stations shows a subsidence trend, and the subsidence rate is between 0.14-11.47mm/yr

Summary

INTRODUCTION

In the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) in 2013, the global sea level rose by 0.19m from 1901 to 2010, with an average sea level rise rate of 1.7mm/a. Previous studies have shown that the vertical land motion rate at tide gauges is the same as the sea level change rate (Teferle et al, 2006; Mazotti et al, 2008; Buble et al, 2010). Using GNSS continuous observation technology to separate the influence of vertical ground motion of tide gauge station on sea level change analysis is a technical means of current coastal sea level rise research (Wöppelmann et al, 2007; Merrifield et al, 2009, Tingqin Du, 2009; Blewitt et al, 2010; Dongxu Zhou et al, 2016). Based on the long-term observation data of the co-located GNSS stations along the Bohai Sea coast, the vertical land motion of tide gauges in this region is calculated and analyzed. The station coordinates were transformed from Geocentric coordinate system (X, Y, Z) to topocentric coordinate system (N, E, U) by the equation (1), where θ, φ is the latitude and longitude of each site, respectively (e.g. Fotiou and Pikridas 2012)

Periodic Analysis of Elevation Time Series

Trend Analysis of Vertical Ground Motion of Tide Gauge

DISCUSSION