Study of Ocean and Earth Dynamics Using Satellite Altimeters

卫星上的微波雷达高度计可以测量全球海面高度，精度可达几厘米，被认为对海洋和固体地球动力学的研究非常有用。在目前的研究中，物理海洋学家和固体地球物理学家之间的合作工作已被提出。该计划派出首席研究员和几名联合研究员参加了1998年在美国和1999年在法国举行的TOPEX/POSEIDON和Jason-1科学工作组联合会议，以交流有关国际卫星测高研究的信息。1998年在福冈召开了科学会议，1999年在东京召开了科学会议，以讨论海拔数据的处理和分析。这些会议邀请了来自英国和澳大利亚的科学家，以促进国际合作。通过这些活动，取得了以下进展：(1)将卫星测高资料与现场海洋资料相结合，获得了日本南部黑潮的长时间运输序列；(2)结合高程资料和现场海洋资料，揭示了大潮的流场和输运以及整个北太平洋的地面环流特征；(3)为了获得动态一致的数据集，开发了将高程数据与海洋数值模式同化的方案；(4)利用高程资料建立了精确的全球日、半日潮模型，并开展了长周期潮和摩擦耗散的研究；(5)模拟了局部重力场的精度估计，并研究了海洋变率与地球重力变率的关系。

Micro-wave radar altimeters on board satellites can measure the sea surface height globally with a ccuracy of a few centimeters, and are considered to be very useful for studies of dynamics both of the oceans and solid earth. In the present study, cooperative works between physical oceanographers and solid earth geophysicists have been intended. This program sent the Principal Investigator and several Co-Investigators to the joint TOPEX/POSEIDON and Jason-1 Science Working Team meetings held in the United States in 1998 and in France in 1999, in order to exchange information about international satellite altimetry studies. Scientific meetings were held in Fukuoka in 1998 and in Tokyo in 1999, in order to discuss about altimetry data processing and analyses. For those meetings, scientists from the Great Britain and Australia were invited in order to stimulate international cooperation. Through those activities, following progresses have been made : (1) A long time series of transport of the Kuroshio south of Japan was obtained by combined use of satellite altimetry data with in situ oceanographic data ; (2) Flow field and transport of the Oyashio and also features of surface circulations of the whole North Pacific were revealed through combined use of altimetry data with in situ oceanographic data ; (3) The scheme has been developed to assimilate the altimetry data to numerical models of the oceans, in order to obtain dynamically-consistent data sets ; (4) A precise global tide model for diurnal and semidiurnal tides was obtained from altimetry data, and also studies on long-period tides and tidal dissipation due to friction were started ; (5) Estimating the accuracy of local gravity field was mulated and also relationship between ocean variability and earth gravity variability was studied.