Study on intraseasonal signal in the tropical region of western Pacific-Indian Oceans

点击翻译按钮获取中文摘要

The first result in the present study is description of intraseasonal signals in the upper layer of the tropical Pacific Ocean using time series data which have been measured by oceanic buoys in the study area between 8゜N and 8゜S. We focused prominent depth, area and period and persistent time of the signal and clarified time and space characters of the intraseasonal signal. The results revealed that, during the 1997-98 EI Nino event which was the largest one in the 20^<th> century, the signal has its contrastive vertical structure between the western and eastern portions with a boundary near the dateline, Father, our study suggested that surface wind variation with intraseasonal time scale over the tropical Indian-Pacific Oceans plays an important role for development of the oceanic signal.The second result is to document these surface wind changes over the tropical Indian-Pacific Oceans. We used satellite scatterometer data which have been available in the recent years. Using these time series data, we constructed gridded data set in our study area, and analyzed wind variability in the intraseasonal period band. The result revealed that the intraseasonal signal in the tropical region has large amplitude in the western Pacific and Indian sectors, and its zonally propagation structure. In particular, we clarified not only eastward propagation of the signal in the onset phase of 1997-98 EI Nino event which was pointed out by previous studies but also westward propagating feature which is dominant in the mature phase of the event.The Above results were presented in the international meetings as well as domestic ones and submitted to scientific journals. Some of them were published yet or will be published in near future.