南海海平面变化及其比容高度和风场间的关系

Sea Level Change in the South China Sea and Its Relations to the Steric Height Variation and Wind

海平面变化研究的目的在于掌握其变化规律,预测其未来变化及其可能对人类生存生活环境产生的影响。本文使用Topex/Poseidon(T/P)卫星高度计资料I、shii(2005)温盐资料、Levitus(2005)温度资料和ICOADS(2005)风场资料对南海海平面高度(SSH),比容高度(SSL)和风的变化进行研究。结果表明,1993~2002年,南海SSH平均以4.7 mm/a的速度上升;但空间分布很不均匀。东北部海区是典型的上升区,其核心值为10.0 mm/a,西南部海区上升较慢。1996~1997年的海平面高度距平(SSHA)和比容高度距平(SSLA)都快速上升。温度变化引起的SSL变化对SSH变化起主导作用,其贡献大约是89.4%。SSH季节变化的年较差约4 cm,而SSL季节变化的年较差约6 cm,比T/P的大。就整个南海的平均而言,SSL的位相比SSH大约提前2个月。同时,经向风应力也是重要的影响因素,非比容高度和经向风应力的同步相关系数达0.7。南海SSH季节变化振幅较SSL小的原因一方面是由于南海SSH存在显著的空间变化(甚至是反相变化),而SSL的空间变化较弱,所以整个南海平均后,会使SSH的振幅变小,而SSL的振幅受影响较小。另一原因是南海西南部的环流和气候特征引起的海平面变化与SSL变化对SSH变化的影响反相。

The purpose of the research on sea level change is to grasp its variation law and forecast its variation in the future and evaluate its influence on the living environment of human beings.In this paper,the variations of sea surface height(SSH),steric sea level(SSL) and wind in the South China Sea(SCS) are analyzed based on the altimeter data of Topex/Poseidon satellite,temperature and salinity data of Ishii(2005) and Levitus(20005),and wind data from ICOADS(2005) database.The results show that the SSH in the SCS rises at a rate of 4.7 mm/a from 1993 to 2002.In most areas,both the SSH and SSL are rising but the rising rates are different from place to place.In the northeast where the SSH rises very fast,the rising rate can reach 10.0 mm/a while in the southwest,the rate is very small.During 1996/1997,both the sea surface height anomaly(SSHA) and steric sea level anomaly(SSLA) in the SCS have a significant rising.The SSL change associated with temperature variation dominates the change of the SSH with a contribution of 89.4%.The range of the seasonal variability of the SSH is about 4 cm,smaller than that of the SSL which is about 6 cm.The phase of the SSL leads the SSH by about two months.By analyzing the relation between the wind stress curl and the non-steric sea level,we found that besides the SSL,the longitudinal wind stress curl is also important to the SSH.The correlation coefficient between non-steric height and longitudinal wind stress is about 0.7.One reason for the range of the SSH being smaller than the range of the thermal contribution is that there exist prominent spatial changes(may be reverse in phase from one place to another) in the SSH,which is much weaker in the SSL.So the range of SSH becomes smaller after averaging over the whole SCS.Another reason is that in the southwestern SCS,the part of the SSH change caused by the circulations and characters of the climate is opposite in phase with the steric effect.