摘要
通过诊断分析和数值模拟,研究了初夏日本东部附近海域负的海温异常对6月鄂霍次克海地区阻塞高压的影响。首先,利用1951—2000年6月份的500hPa月平均位势高度资料计算了历年6月鄂霍次克海阻塞高压指数,并分析了它的变化规律。其次,对阻塞高压年和非阻塞高压年的500hPa位势高度及其异常进行合成和相关分析表明,阻塞高压年,鄂霍次克海地区存在明显的正高度异常,贝加尔湖附近为负高度异常,乌拉尔山附近为正异常,欧亚中高纬度地区纬向呈“+-+”型;日本东部为负高度异常,东亚呈偶极型。这种高度异常形势为鄂霍次克海阻塞形势的形成和维持提供了大尺度环流背景。对鄂霍次克海阻塞高压指数与同期北太平洋海温的分析结果表明,当鄂霍次克海阻塞高压活跃时,日本东部附近海域为明显的负海温异常。此外,对1998年6月的典型个例的分析也发现,当年强盛的阻塞形势维持时,日本东部附近存在强大的负海温异常。最后,设计假想的负海温异常试验,利用NCAR CAM3模式模拟了日本东部附近海域负的海温异常对初夏欧亚大气环流的影响。结果表明,在该地区5和6月加入较大负的海温异常后6月份鄂霍次克海地区500hPa会产生最大超过4dagpm的正位势高度异常并经检验显著,这种正的高度异常显然对鄂霍次克海阻塞高压的形成十分有利。
This study examines the impact of the anomaly of the sea surface temperature （SSTA） off the east coast of Japan on the Okhotsk high in early summer by diagnostic analysis and numerical simulation. Firstly, based on the 500 hPa geopotential height data for June from 1951 to 2000, the index of Okhotsk high （IOKH） is calculated and analyzed. The results indicate that the IOKH had obvious inter-annual and inter-decadal variations, and there were nine years of high IOKH and eight years of low IOKH in the fifties years. Secondly, the composite analyses of the 500 hPa geopotential height and its anomaly for blocking years and non-blocking years suggest that in the blocking year, the potential height anomaly displayed a ＂＋ （the Ural mountains） - （the Baikal lake） ＋ （the Okhotsk Sea） ＂ pattern across Eurasia in the mid-high latitudes, and a ＂ ＋ - ＂ pattern from high to low latitudes over the East Asia, which is in favor of the formation and the maintenance of the Okhotsk high. The relationship between the IOKH and the SSTA over the north pacific is further investigated in early summer by using correlation and composite analysis. We find that when the blocking circulation occurred over the Okhotsk Sea, there was an obvious negative SSTA off the east coast of Japan in early summer. In order to confirm the analysis result we simulate the impact of the negative SSTA on the atmospheric circulation anomaly over the East Asia through the control and sensitive experiments of the NCAR CAM3 model. The simulation shows that the assumed negative SSTA off the east coast of Japan in May and June does result in a significant positive anomaly more than 4 dagpm of the 500 hPa geopotential height over the Okhotsk Sea and a negative anomaly off the east coast of Japan in June, which might contribute to the formation and development of the Okhotsk high in June.
出处
《气象学报》
CAS
CSCD
北大核心
2006年第4期518-526,共9页
Acta Meteorologica Sinica
基金
科技部973项目(2004CB418300)
国家自然基金委项目(40545019)
关键词
鄂霍次克海高压
海温异常
数值模拟
Okhotsk high, Sea surface temperature anomaly, Numerical simulation
