联合卫星测高、GRACE与温盐数据分析红海海平面变化季节性特征

本文利用卫星测高、GRACE与温盐数据监测2003-2014年红海海平面变化,并分析了蒸发降水以及亚丁湾-红海质量交换对红海质量变化的影响。红海地区单一的温盐数据存在覆盖不全或质量不佳的问题,综合CORA、SODA与ORAS4温盐数据估算结果得到平均比容海平面变化,以改善比容信号的精度。针对GRACE数据处理过程中截断与空间平滑滤波引起的泄漏误差,提出改进尺度因子纠正泄漏误差,利用卫星测高数据进行模拟实验验证了改进尺度因子的有效性。利用传统尺度因子和改进尺度因子反演的红海质量变化周年振幅分别为16.1±1.3 cm和20.5±1.7 cm,利用卫星测高和温盐数据估算的质量变化周年振幅为20.2±1.0 cm,表明改进尺度因子可有效减小泄漏误差的影响,改善GRACE模型反演红海质量变化的精度。卫星测高、GRACE卫星重力数据以及平均温盐数据具有较好的一致性,联合GRACE和温盐数据估算的红海综合海平面变化周年振幅为16.6±1.7 cm,与卫星测高估算的总海平面变化周年振幅(16.2±0.9 cm)基本一致,表明多源数据可构成完整的红海海平面监测手段。相比于降水-蒸发作用,红海质量变化受红海与亚丁湾的海水质量交换的影响更为显著,其主导了红海质量的季节性变化。

Seasonal sea level variations in the Red Sea inferred from satellite altimetry,GRACE and temperature and salinity data

Satellite altimetry, GRACE and temperature-salinity datas are used to analyze the sea level variations in the Red Sea over the period from 2003 to 2014, and we explore the precipitation-evaporation effect and the water exchange between the Gulf of Aden and the Red Sea on local sea level variations. Due to the poor coverage and imperfection for single temperature-salinity dataset, we averaged three datasets (CORA, SODA, and ORAS4) to improve the accuracy of the steric sea level variations. In order to correct the leakage errors induced by truncation and spatial smoothing during GRACE postprocessing, we proposed an improved scale factor, which is validated by using satellite altimeter measurements. Annual amplitudes of mass-induced sea level variations observed by GRACE measurements for traditional and improved scale factor are 16.1±1.3 and 20.5±1.7 cm, respectively, and that inferred from satellite altimetry and temperature-salinity data is 20.2±1.0 cm, indicating that the improved scale factor can restore the leaked signals effectively. Results demonstrate good agreement among the satellite altimetry, GRACE and temperature-salinity data. Annual amplitude of the total sea level variations combining the GRACE mass-induced and temperature-salinity steric sea level variations is 16.6±1.7 cm, which is consistent with satellite altimeter results (16.2±0.9 cm), implying that closed-loop verification can be established among the different sea level measurements in the Red Sea. Mass exchange with the Gulf of Aden through the Bab-el-Mandeb strait has an obvious effect on the mass variations in the Red Sea, which dominates the seasonal signals of mass variations in the Red Sea.