长江流域旱涝年低频风场分布和演变的差异
投稿时间:1995-07-08  修订日期:1996-10-30  点此下载全文
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作者单位
黄静 南京气象学院气象学系, 南京 210044 
朱乾根 南京气象学院气象学系, 南京 210044 
基金项目:国家自然科学基金会资助项目
中文摘要:从低频风场出发研究低频振荡在旱涝年的年际差异以及与降水的关系。研究表明:旱涝年我国东部环流系统低频分量所占比重显着不同;与长江流域降水变化联系的低频风场的特点及变化有显着不同。1980年(长江流域涝年)降水的变化与东亚季风区内的低频振荡有密切的关系,尤其是副热带季风的低频振荡。低频振荡在东亚季风区内阶段性地向北传播,且具有准8候的周期,从而导致降水的周期变化。而1988年(长江流域旱年)降水的变化与东亚季风的低频振荡关,而与控制东亚北部的强大的低频涡旋有着密切的关系,这个强大的低频涡旋是由日本岛以东洋面上的低频涡旋北进西旋发展演变而来,且这种移动和演变也具有准8候的特点,并且伴随着降水的增加或减少。
中文关键词:低频振荡  旱涝  降水  年际变化
 
MLCB LOW-FREQUENCY WIND IN FLOOD/DROUGHT YEARS AND ITS INTERANNUAL DIFFERENCE
Abstract:Based on the low frequency windfields, study is made of the difference in low-frequency oscillation (LFO) between flood-and drought-hit years and the relation to rainfall. Results suggest that in such years the low-frequency component makes up greatly varying portion for the circulation systems in east China and the MLCB (mid-lower Changjiang basins) rainfall-related wind features and variation are quite distinct; in 1980 as the flood year over the MLCB the change in precipitation is closely associated with the LFO in the East Asian monsoon region, especially in subtropical monsoon, with its northward propagation in a phatic manner, marked by a quasi-8 pentad period, thus responsible for the periodic variation in rainfall whilst in 1988 as the year of drought the rainfall change bears no relation to East-Asian monsoon′s LFO but to a vigorous low frequency vortex dominating the northern portion of East Asia, which originates from the one over the waters east of Japan moving north and then turning west, and the movement and development are at a quasi-8 pentad period, too, leading to change in rainfall over the MLCB.
keywords:low-frequency oscillation  flood/drought  rainfall  interannual variation
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