Recent positive trend in heavy rainfall in eastern Japan and its relation with variations in atmospheric moisture
Recent positive trend in heavy rainfall in eastern Japan and its relation with variations in atmospheric moisture
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日本东部近期强降雨的积极趋势及其与大气湿度变化的关系
DOI：
10.1002/joc.2269
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
H
中科院分区：
文献类型：
--
作者：
Iwasaki;H
利用具有高空间分辨率的AMeDAS（1976-2006）31年的每小时降雨量数据，研究了日本东部暴雨的近期趋势。对1980-1989年和1997-2006年两个10年周期的暴雨进行非参数Wilcoxon秩和检验，并将所确定的趋势与近期大气湿度变化进行比较，发现两个地区的暴雨趋势具有显著的正趋势。一个是山脉东南麓周围的地区，那里的傍晚对流最大值自然占主导地位。在没有天气尺度扰动经过该地区的日子里，晚上的暴雨有所增加，并向山区地区发展的热力引发的局地环流占主导地位。此外，在最近的高空观测站，对流天气时850 hPa的比湿也有所增加。这是合理的建议，大气稳定度的下降，由于比湿度的增加，增强了现有的机制，晚上对流最大值，是特定的东南山脚下。另一个代表性的地区是太平洋沿岸地区，清晨对流最大值是自然占主导地位的。当天气尺度扰动经过该地区时，清晨的暴雨有所增加。积雨云在大气稳定度低的月份变得活跃，但大气稳定度不受低层大气中水汽的控制。值得注意的是，尽管这两个区域之间的距离为150公里，但水汽的变化对这两个区域最近的趋势有不同的影响。皇家气象学会
A recent trend in heavy rainfall in eastern Japan was studied using 31 years' worth of AMeDAS (1976–2006) hourly rainfall data having fine spatial resolution. The non‐parametric Wilcoxon rank‐sum test was applied to the heavy rainfall in two 10‐year periods (1980–1989 and 1997–2006), and the trends determined were compared with recent variations in atmospheric moisture.Two regions were found to be representative of the significant positive trend in heavy rainfall. One is the region around the southeastern foot of the mountains, where the evening convective maximum was naturally dominant. Heavy rainfall increased in the evening on days when no synoptic‐scale disturbances passed over the region and thermally induced local circulation toward the mountainous region prevailed. In addition, the specific humidity at 850 hPa also increased on convective days at the nearest upper air observation site. It is reasonable to suggest that the decrease in atmospheric stability due to the increase in specific humidity enhanced the existing mechanism for the evening convective maximum that is specific to the southeastern foot of the mountains.The other representative region is the region around the Pacific coastline, where the early morning convective maximum was naturally dominant. Heavy rainfall increased in the early morning on days when synoptic‐scale disturbances passed over the region. Cumulonimbus clouds became active in the months when atmospheric stability was low; however, the atmospheric stability was not controlled by the water vapour in the lower atmosphere. It was notable that the variations in the water vapour made different contributions to the recent trends in these two regions, even though the distance between the two regions is 150 km. Copyright © 2011 Royal Meteorological Society