印度洋的风浪、涌浪和混合浪的时空特征

为了展现印度洋的海浪特征,利用来自欧洲中期天气预报中心的ERA-40海浪再分析资料,对印度洋的海表风场、风浪、涌浪、混合浪场进行研究,主要分析了季节特征、月变化特征、风速和波高的变化趋势、涌浪指标,定义了南印度洋西风指数和涌浪北伸脊点。结果表明:印度洋的风浪场与海表风场整体上对应较好,尤其是季风期间的北印度洋,涌浪场与混合浪场对应较好;从波高来看,阿拉伯海在1-5月和9-12月的涌浪以及孟加拉湾全年的涌浪对混合浪的贡献大于风浪;印度洋海表风速呈显著递增的区域主要集中在咆哮西风带和30°S以北,风浪波高变化趋势的分布与风速大体一致,大部分海域的涌浪波高、混合浪波高表现显著性逐年递增;印度洋的涌浪在混合浪中占据主导地位,40°S以北的涌浪常年向北传播,且南印度洋西风带西南季风的强度直接决定着涌浪北传的程度。

Temporal and spatial distribution of windsea, swell and mixed wave in Indian Ocean

To exhibit the characteristics of wave field in the Indian Ocean, the characteristics of wind field, windsea, swell and mixed wave,were presented using the ERA-40 wave reanalysis data and wind field data from European Centre for Medium-Range Weather Forecasts(ECMWF).The seasonal characteristic, monthly characteristic, long-term trends of wind speed and wave height, swell index were introduced. Definition was also given to "South Indian Ocean westerly index" and "north stretches point of swell". Results show that, there is a good agreement between the wind field and the windsea field, especially the monsoon seasons. There is also an excellent agreement between the swell and mixed wave. Based on the wave height, the swell has a dominant role in the mixed wave from January to May and from September to December, while the windsea has a dominant role from June to August in the Arabian Sea. In the Bay of Bengal, the swell has a dominant role in the mixed wave all year round. The areas with significant increase trend in wind speed are mainly located in the roar westerly belt, north of 30°S, similar as the windsea wave height. The swell wave height and mixed wave height in most of the Indian Ocean exhibit an obvious increase trend. The swell plays a dominant role in the Indian Ocean. In the north of 40°S, the swell direction is toward north all year round. The strength of west wind in the southern Indian Ocean determines the stretch of swell toward the north waters.