印度洋及太平洋海表盐度时空特征分析

目前对印度洋和太平洋海表盐度变化的大尺度分析相对较少,Aquarius作为海表盐度的观测卫星,其观测数据在分析海表盐度时空特征时有着不可替代的优势。为了降低观测资料本身的误差对分析结果的影响,文本首先利用质量—距离双重加权方法生成新的高精度Aquarius网格化月均海表盐度场,并基于此盐度场和Argo资料对2011-09至2015-05印度洋及太平洋海表盐度的时空特征进行了分析。结果显示,盐度分布和纬度有明显的相关性,整体呈现低、高纬偏低,中纬偏高的态势,纬度极值随时间并没有很明显的变化,然而时间最大值随纬度的变化曲线呈现明显的以赤道为中心的近似中心对称分布特征。分析显示印度洋和太平洋盐度分布主要包括4个高盐区和4个低盐区,但每个盐度区的变化趋势与幅度不尽相同。

Spatiotemporal characteristics of sea surface salinity of Indian and Pacific Oceans

Sea Surface Salinity (SSS) is a key element of marine dynamic environment that plays an important role in many sea gas interactions and ocean processes. At present, large-scale analysis of Indian and Pacific Oceans are limited and the majority of investigations are based on in situ observation or reanalysis data. As an SSS observation satellite, Aquarius has a unique advantage in analyzing the characteristics of SSS distribution. Therefore, this study aims to analyze distribution characteristics of surface salinity in the Indian and Pacific Oceans based on Aquarius and Argo data.New high-accuracy monthly 0.25° × 0.25° gridded SSS fields were first generated using dual quality-distance weighting method based on Aquarius L2 orbital SSS data to reduce the influence of observation data error on the analysis results. SSS distribution characteristics of Indian and Pacific Oceans are analyzed on the basis of these new and gridded Argo SSS fields.The analysis results showed that low SSS values are obtained in low and high latitudes and high SSS values are achieved in the middle latitude. The latitude in which the average SSS reaches the maximum value has no evident change with month, while the month in which the average SSS reaches the maximum value in each latitude line is estimated to be symmetrical with the equator and June as the center. A high-salinity zone exists in each midlatitude of North and South Pacific as well as southern Indian Oceans. Arabian Sea in the northern Indian Ocean is also a high-salinity area. The Bay of Bengal in the northern Indian Ocean and the tropical Pacific are low-salinity areas. Although an atypical region, SSS rangeability of the area near the land of southeastern China is very high. The periodic change of SSS in this area has a certain impact on the frequency and intensity of storm surge in the southeastern coast of China. The analysis results between Aquarius SSS and Argo SSS are similar, except for a few differences. One typical difference is an evident coalescence zone along the latitude of 8°N in the Pacific Ocean according to Aquarius SSS fields but is missing according to Argo SSS fields.Therefore, SSS values have clear correlations with latitude. Four high-salt areas and four low-salt areas are observed in this region, and each region is characterized with different change trends and amplitudes. Mutual responses are observed among these areas.