A Study of Mechanism of "Yamase" Events and Their Prediction

“山濑”事件发生机制及其预测研究

基本信息

批准号：
05452373
负责人：
ASAI Tomio
金额：
$ 3.65万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Observational and theoretical studies have been made to understand mechanism of "Yamase" and the results obtained are summarized as follows.1. A composite analysis of the five-day mean 500 hPa weather charts for summer seasons from 1958 to 1989 has been performed and the characteristic atmospheric circulation pattern is found to be associated with Yamase-type weather in the northern Japan.A factorial analysis is applied to the daily mean temperature anomalies obtained at the 16 weather stations in the east side of the northern Japan during June and July for the three years from 1990 to 1992. Anomalously low temperatures on the Pacific Ocean side are observed about 2 days later than those in the Okhotsk Sea side.2. A mechanism to cause the cool and humid weather in Yamase events is investigated with use of a two-dimensional numerical model which includes processes of cloud formation and long-wave radiation. A prediction experiment has also been made for the remarkable Yamase period from 17th to 19th July 1993 with use of a revised version of the Japan Spectral Model, JMA.The following three problems are shown to be crucial to clarify mechanism of intense Yamase events with fog and/or stratus : (1) thermodynamical conditions of the lower atmosphere in the high pressure system over Okhotsk Sea, (2) role of surface buoyancy flux during the southward movement of cooled airmass from Okhotsk Sea, and (3) interaction among a) amount of water vapor phase change b) cooling rate of cloud-top radiation and c) rate of entrainment into a mixed layr on the evolution of the moist convective mixed layr.

已经进行了观察性研究和理论研究来理解“ yamase”的机制，并且获得的结果总结如下1。已经进行了五天平均500 hpa天气图的综合分析，从1958年到1989年进行了夏季的季节，并且发现了特征性的大气循环模式与日本北部北部的yamase型天气相关。在太平洋一侧比Okhotsk Sea Side的人晚约2天。2。通过使用二维数值模型，研究了一种导致Yamase事件中凉爽和潮湿天气的机制，该模型包括云形成和长波辐射的过程。还通过使用日本光谱模型的修订版，JMA，JMA。表明以下三个问题对于阐明具有雾和/或层的强烈的yamase事件的机制至关重要，这也是对1993年7月17日至19日的显着的yamase期间进行的预测实验。来自Okhotsk海的冷却气气，以及（3）a）水蒸气相变的量之间的相互作用b）云顶辐射的冷却速率和c）夹带速率在潮湿的混合混合层的演变上陷入混合层。