1993—2016年中国近海海平面时空变化趋势

区域海平面变化是目前气候变化研究的热点问题.海平面变化具有时间和空间的异质性,分析海平面变化,应充分考虑时间和空间的差异.基于集合经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)、最小二乘法,利用卫星高度计、验潮站数据,分析了1993—2016年间中国近海及周边海域海...

Spatial-temporal Variation of the Sea Level in Adjacent Seas of China From 1993 to 2016

Regional sea level change is one of key topics of the climate research.The sea level change is usually inhomogeneous in spatial distribution or temporal variation,thus it is important to take both of them into account in the analysis of the sea level change.Based on the AVISO altimetry data and the tide gauge data,the spatial-temporal change of sea level in the adjacent Seas of China during 1993—2016 are studied using the Ensemble Empirical Mode Decomposition(EEMD)and the Least Square method(LS).Results indicate a continuous but spatially and temporally inhomogeneous increase in sea level.Three patterns of the sea level change are identified:the rate of sea level rise in coastal waters has been increasing between 1993 and 2016,while that in offshore area has been decreasing;in the area to the west of the Pacific,the sea level change trend is transformed from rising to descending.The spatial distribution of the mean rate of sea level change over 1993—2016 derived by EEMD and LS algorithms illustrate that the change rate along the coast(6 mm/a)is much higher than that off the coast(2 mm/a),although less differences exist along Guangzhou coast and tropical areas.For comparison,linear and non-linear trends of spatially averaged sea level change in coastal areas,offshore and part of the West Pacific are calculated,and the the non-linear trend shows that the spatially-mean sea level rise rate in coastal areas has accelerated from 3.65 mm/a in 1993 to 5.03 mm/a in 2016;the offshore sea level rise rate has gradually decreased from 4.51 mm/a in 1993 to 3.8 mm/a in 2016;while in the areas to the West Pacific the sea level rise rate decelerated from 9.5 mm/a in 1993 and to a declining rate of 2.27 mm/a in 2016.To verify the consistency,the tide gauge data at Dalian,Kanmen and Hong Kong were also decomposed using EEMD,and the results are in good agreement with the AVISO results except Dalian where the sea level rise rate decreased.