近50 a塔里木河流域生长季大风日数变化特征及对特色林果业的影响

大风是塔里木河流域特色林果业的主要气象灾害. 在对塔里木河流域44个气象站大风资料进行质量控制基础上, 统计分析了1960-2011年作物生长季节(3-10月)月大风日数. 结果表明: 近50 a来塔里木河流域生长季节内各月大风日数的长期变化具有显著的递减趋势, 递减速度为0.8~2.6 d·(10a)^-1, 趋势系数为-0.37~-0.8, 通过了95％的秩检验; 但二次和三次系数为正, 反映出生长季节大风日数近期呈现回升的趋势. 周期分析发现, 生长季节大风日数存在11~15 a左右的中期振荡, 5~8 a的短周期振荡, 以及5 a以下的小扰动. 虽然从更高的20 a频域尺度看, 20世纪80年代中期之后是大风的少发时期, 但从15~16 a周期上看, 生长季节大风日数亦开始有回升的趋势. 尤其是在春末及夏秋(4-9月)塔里木河流域特色林果业的关键生长时期, 大风日数占整个生长期(3-10月)的89%. 虽然, 近10 a平均每年大风日数只有20世纪60年代的一半, 但每年平均也有7 d之多, 并没有脱离大风的威胁, 而且近期大风日数还有回升的趋势. 因此, 春末及夏秋(4-9月)是塔里木河流域特色林果业的重点防风时期. 从空间分布上看, 南疆东部平均每年大风日数1~2 d, 是塔里木河流域生长季节防风重点地区.

Variation Characteristics of the Gale Days during the Growth Season in Recent 50 Years and Its Impact on the Local Special Forest Fruits in the Tarim River Basin

Gale is the main meteorological disaster to local special forest fruits in the Tarim River basin. A statistics of monthly gale days in crop growth season (Mar. to Oct.) from 1960 to 2011 was made for 44 meteorological stations. It is found that as the long-term change there is a significant decline trend of the gale days each month during the growth season in the basin, with a decline rate of 0.8~2.6 days per ten days, and a trend coefficient of -0.37 to -0.8, which passes the rank tests of 95%. The quadratic and cubic coefficients are positive, which reflects that the gale days in the growth season have a rebound trend recently. It is found by periodic analysis that there are a mid-oscillation of 11~15 a, a short-period oscillation of 5~8 a and a small perturbation of less than 5 a of the gale days in growth season in the basin. In regard to higher frequency scales of 20 a, it is found that after the mid-1980s there is a phase with less gale days. However, in regard to period of 15~16 a, an increase trend of gale days in growth season can be seen. In especial, the gale days account for 89% of the entire growth season (Mar. to Oct.) in the basin, especially in the late spring, summer and autumn (Apr. to Sep.), when the local special forest fruits grow flourishingly. Although the gale days per year in recent decades are half of the 1960s only, there are 7 days per year on average, still under the threat of gale. However, it is rising again. Therefore, the late spring, summer and autumn (Apr. to Sep.) are the critical periods to defense the gale in the basin. From the point of the spatial distribution view, the gale days are 1~2 days per year in east of the southern Xinjiang, where is the key point to defense the gale in growth season in the basin.