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气象:2014,40(5):530-540
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1998年夏季青藏高原东南部降水30~60 d低频振荡特征
(1.南京信息工程大学,气象灾害省部共建教育部重点实验室,南京 210044;2.内蒙古自治区气候中心,呼和浩特 010051)
Characteristics of Precipitation 30-60 d Oscillation over the Southeast of Tibetan Plateau in Summer 1998
(1.Key Laboratory of Meteorological Disaster of Ministry of Education, NUIST, Nanjing 210044;2.Inner Mongolia Climate Centre, Hohhot 010051)
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投稿时间:2013-03-19    修订日期:2013-10-22
中文摘要: 根据地面观测站的逐日降水资料及NCEP/NCAR逐日再分析资料,分析了1998年夏季青藏高原东南部地区的低频降水特征,并重点讨论了30~60 d低频降水正、负位相期间相关要素场低频分量的异常分布及传播特征。结果表明:(1)1998年高原东南部降水存在10~20、20~30以及30~60 d周期的低频振荡,其中30~60 d振荡的正(负)位相基本对应着降水的盛(间歇)期。(2)在降水正(负)位相期间,高原南侧存在一个低频气旋(反气旋),而日本海上空维持着一个异常低频反气旋(气旋),受高原南侧低频气旋(反气旋)东北侧的偏南(北)气流以及日本海上空低频反气旋(气旋)西南侧的偏南(北)气流的共同影响,高原东南部为明显的低频水汽辐合(散)区。(3)在低频降水正位相期间,高原地区经孟加拉湾至中南半岛到南海均为低频热源区;负位相,热源、汇低频分量的分布与正位相基本相反。(4)1998年夏季存在从西太平洋经长江中下游西传至高原地区的30~60 d整层积分水汽通量辐合(散)和100 hPa低频辐散(合),且西传至高原东南部时基本与高原东南部30~60 d低频降水的正(负)位相对应。
Abstract:The characteristics of precipitation low frequency oscillation (LFO) over the southeast of Tibetan Plateau (TP) and especially the abnormal distribution and propagation of the 30-60 d filtered fields between positive and negative phases of precipitation LFO are investigated using daily NCEP/NCAR reanalysis and the observed daily rainfall data in 1998. The results are shown as follows: (1) There are several main periods of oscillation including the 10-20 d, 20-30 d and 30-60 d periods, and several significant rainfalls mainly occur in the positive phases of the 30-60 d oscillation, while significant negative rainfall anomaly in the negative phase. (2) During the positive (negative) phase, there is a low frequency cyclone (anticyclone) to the south side of the TP, and a low frequency anticyclone (cyclone) in the Sea of Japan. The southeast TP is influenced both by the southerly winds of the northeast side of the cyclone and the southerly winds of the southwest side of the anticyclone, and it is the low frequency moisture convergence (divergence) area. (3) During the positive phase, the southeast TP, Bay of Bengal (BOB) and South China Sea (SCS) are all low frequency heat source areas, but the 30-60 d filtered heat source/sink fields are opposite in the negative phase. (4) There exist westward propagating convergence (divergence) of moisture fluxes LFO and the 100 hPa divergence (convergence) LFO over the southeast TP which propagate from the West Pacific by the way of middle and lower reaches of Yangtze River, and they correspond well with the positive (negative) phase of precipitation LFO over the southeast TP when they propagate to the southeast TP.
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基金项目:公益性行业(气象)科研专项(GYHY201006020)和国家重点基础研究发展规划项目(2012CB955204)共同资助
引用文本:
刘炜,周顺武,智海,2014.1998年夏季青藏高原东南部降水30~60 d低频振荡特征[J].气象,40(5):530-540.
LIU Wei,ZHOU Shunwu,ZHI Hai,2014.Characteristics of Precipitation 30-60 d Oscillation over the Southeast of Tibetan Plateau in Summer 1998[J].Meteor Mon,40(5):530-540.