湖南邵阳干旱特征及成因分析

Characteristics and Causes of Drought in Shaoyang, Hunan Province

摘要: 利用邵阳市10个站点的月降水资料、NCEP/NCAR的再分析资料，分析了干旱特征、大气环流特征。1960~2020年平均每年共出现干旱31.4站次。重旱主要出现在秋季，其次为冬季。重旱整体呈下降的趋势，倾向率为−0.35次/10a。特旱主要出现在秋季特旱的趋势与重旱相反，呈上升的趋势，倾向率为0.16次/10a。500 hPa高度场上欧亚中高纬呈“两脊一槽”的环流形势分布，邵阳处于高度场正距平控制，中低层为北风异常，冷空气太强，缺少水汽输送，不利于邵阳地区的降水。较强的水汽输送通量路径未经过湖南，湖南整体的水汽条件不充沛，且水汽以辐散为主，不利于降水的发生。

Abstract: Using monthly precipitation data from 10 stations in Shaoyang City and NCEP/NCAR reanalysis data, the drought characteristics and atmospheric circulation characteristics are analyzed. From 1960 to 2020, there was an average of 31.4 drought stations per year. Severe droughts mainly occurred in autumn, followed by winter. The overall severe drought showed a downward trend, with a tendency rate of −0.35 times/10a. The extreme drought mainly occurs in autumn. The trend of extreme drought is opposite to that of severe drought, showing an upward trend, with a tendency rate of 0.16 times/10a. In the 500 hPa altitude field, the Eurasian mid-high latitudes present a circulation pattern of “two ridges and one trough”. Shaoyang is under the control of the positive anomaly of the altitude field. The north wind is abnormal in the middle and low layers. The cold air is too strong and lacks water vapor transmission, which is not conducive to the Shaoyang area. The strong water vapor transport flux path does not pass through Hunan, the overall water vapor conditions in Hunan are not sufficient, and the water vapor is mainly divergent, which is not conducive to the occurrence of precipitation.