1981～2013年宝鸡地区能见度变化趋势及突变分析

摘要

选取1981～2013年位于宝鸡各县区的11个地面气象台站人工观测的大气水平能见度数据，采用Mann－Kendall趋势突变检验法、滑动t检验法以及小波分析法对能见度进行分析，以了解其变化趋势和突变。结果表明：扶风县、凤翔县、陇县、岐山县和千阳县站点观测能见度整体呈下降趋势，其他站点的整体呈上升趋势；能见度最大和最小变率分别出现在陈仓和凤翔站点，分别为2．46和0．085 km1／0年。能见度增加的县区主要集中在南部秦岭、渭河谷地和东北方向的麟游，年均能见度降低的县区形成了东南－西北走向的带状。宝鸡市年均能见度呈上升趋势，变率为5．11 km／10年，2011～2013年该市平均能见度为17．65 km。低能见度（2．0～9．9 km）的比例呈现下降趋势，较好能见度（20．0～39．9 km）的百分比呈现上升趋势。宝鸡市年均能见度存在多时间尺度，其年、四季主中心周期在24～28年范围内波动，且都为两次准周期震荡，各次周期相差较大。 Mann－Kendall突变检验和滑动t检验结果表明通过显著性检验的5个站点除陈仓区外，其余各站点均出现突变，且突变类型为多个类型叠加。%According to the data of air horizontal visibility which were observed manually from 1981 to 2013 at eleven ground meteorological stations of Baoji city, the variation trend and abrupt changes of visibility in Baoji area were analyzed by using the methods of Mann-Kendall tendency abrupt-change test, moving t-test, and wavelet analysis.The annual mean values of visibility generally showed a decreasing trend at Fufeng, Fengxiang, Long county, Qishan and Qianyang stations, and generally revealed a rising trend at the other stations.The maximum and minimum variation rate of the annual mean visibility were 2.46 km/10 a at Chencang station and 0.085 km/10 a at Fengxiang station,respectively. The counties with increasing annual mean visibility were mainly distributed in the southern Qinling , the Wei river valley and the northeastern Linyou .The counties with decreasing annual mean visibility formed a southeast-northwest zonal region.The annual mean visibility of Baoji city showed a rising trend with the variation rate of 5.11 km/10 a, and the mean visibility value of this city from 2011 to 2013 was 17.65 km.The proportion of low visibility value (2.0~9.9 km) revealed a decreasing trend, while the percentage of better visibility value (20.0~39.9 km) re-vealed a rising trend. The annual average visibility in Baoji had multi-time scales, its annual and seasonal primary center cycles fluctuated from 24 a to 28 a, and they all had two quasi periodic oscillations with largely different minor cycles .The results of Mann-Kendall abrupt-change test and moving t-test indicated that the abrupt changes of annual mean visibility appeared at 5 sta-tions ( except for Chencang station) which had passed the significant test, and the abrupt-change type was the overlaying of many types.