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A model for forecasting water temperature of a small bay at Sanriku coast

三陆海岸小海湾水温预测模型

基本信息

批准号：
16510004
负责人：
NAGASHIMA Hideki
金额：
$ 2.5万
依托单位：
Tokyo University of Marine Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16510004/
关键词：
Otsuchi Bay Heat budget Water temperature forecasting Wind driven current Water exchange Turbulent dissipation 水温変動三陸内湾

项目摘要

To develop a model for forecasting water temperature of a small bay, Otsuchi Bay, located at the Sanriku coast of Japan, we clarified physical process of the bay, such as heat balance, water circulation, turbulent activity and so on. We first investigated inter-annual variation of heat budget through the sea surface of the bay by using weather and sea condition data supplied by International Coastal Research Center, the University of Tokyo and neighborhood meteorological stations, the Japan meteorological agency. The results show a clear difference in heat budget between the 80' and 90'. This difference is attributed to differences in both downward shortwave radiation and wind speed in Tohoku area. Second, we have carried out a measurement of turbulent activity both at the bay mouth and inner bay. The energy dissipation rate is estimated at the order of 10^<-7> to 10^<-8> W/kg in general, but sometimes up to the order of 10^<-6> W/kg at the depth of 15 to 20m of the inner bay. Third, we simulated wind driven water circulation by using GETM (General Estuarine Transport Model). The results are compared quite well with the circulation pattern obtained by the observational results. The vertical circulation caused by westerly in winter season shows the out flow above the depth of 8-10m and inflow below it. We also tried to investigate a statistical model for forecasting water temperature of the bay. On the basis of the data from 1978 to 2003, statistical coefficients of AR (Auto Regressive model) and ARMA (Moving Average of Auto Regressive model) are estimated. By using these coefficients, we calculated water temperature variation in 2004. As a result, this model forecasts water temperature of the bay with the bias of 0.58℃ and standard deviation of 0.88℃.

为建立日本三陆海岸小海湾大槌湾的水温预报模型，阐明了海湾的热平衡、水循环、湍流活动等物理过程。我们首先利用东京大学国际海岸研究中心和日本气象厅附近气象站提供的天气和海况资料，研究了海湾海面热收支的年际变化。结果表明，80′和90′的热收支存在明显差异。这种差异归因于东北地区向下短波辐射和风速的差异。其次，我们对海湾口和内湾的湍流活动进行了测量。一般情况下，能量耗散率估计为10^<-7> ~ 10^<-8> W/kg，但有时在15 ~ 20m的内舱深度可达10^<-6> W/kg。第三，利用GETM （General estuary Transport Model）模型模拟风驱动水循环。结果与观测结果得到的环流型相比较很好。冬季由西风带引起的垂直环流表现为8 ~ 10m深度以上为流出流，10m以下为流入流。我们还尝试研究了一个预测海湾水温的统计模型。利用1978 ~ 2003年的数据，估计了自回归模型（AR）和自回归模型移动平均（ARMA）的统计系数。利用这些系数，我们计算了2004年的水温变化。结果表明，该模型预测海湾水温的偏差为0.58℃，标准差为0.88℃。