全球水质量迁移对海平面空间模式周年变化的影响

Annual sea level fingerprint caused by global water mass transport

大气、陆地水和海洋之间的水质量迁移对海平面的影响一般假定为均匀薄层分布.但实际上,水质量负荷重新分布一方面会使地壳产生形变,另一方面会引起重力位势场变化(引力位和离心力位),这都会对海平面时空变化特征产生影响,两方面之和称为负荷自吸引效应(SAL).海洋模式模拟的时变洋底压力结果一般符合Boussinesq假设即体积守恒,忽略了大气、陆地水和海洋之间水质量交换的影响.本文基于海平面变化方程,联合陆地水模型、大气地表气压模型、海洋洋底压力模型和GRACE反演的冰川质量变化,详细讨论了2003—2010年SAL对海平面周年变化的影响.主要结论有:(1)SAL对全球海平面周年变化有显著影响,振幅在1.3～19mm.其中近海岸和低纬度区域受影响较大.(2)在SAL引起的海平面周年振幅变化的因素中,陆地水储量变化因素最大,大气因素次之,非潮汐海洋影响最小.但非潮汐海洋对海平面周年相位空间变化的影响最为复杂.(3)通过与国际长期验潮站观测数据结果比较,在ECCO海洋模式估计的洋底压力结果中引入SAL,能多解释约5.3%观测信号方差.

The cycle of water reserves on Earth is generally measured by the impact of global mean sea-level. The effects of water exchange among Atmosphere, Hydrology and Ocean （AHO） are always seen as a uniform thin layer. But in fact, it has been demonstrated that the mass exchange among AHO will result in a highly nonuniform patterns of sea level change due to the crust deformation and self-attraction loading （SAL） effect called sea-level fingerprints. Generally, ocean model obeys the Boussinesq hypothesis that volume conserves while ignoring the SAL effect. Here we analyze the SAL effect of AHO during 2003 and 2010 through solving the sea level function. The main results are. （1） while considering SAL effect, the spatial patterns in the annual terms of sea level changes vary significantly especially near coastal areas and at low-latitude regions. The maximum amplitude can reach 1.3~19 mm. （2） At annual time-scale, the impact of hydrology is maximal, and less is atmosphere and ocean, while SAL effect caused by ocean has the most complex phase spatial distribution. （3） When SAL effect is included in ocean ECCO OBP model, it can explain more 5.3 G variance reduction from a global set of tide gauges.