秦岭南北地区光合有效辐射时空变化及突变特征

基于秦岭南北地区47个气象站1960-2011年的逐日气象数据,通过Angstrom方程和Penman-Monteith公式计算了各站点的光合有效辐射(PAR),并借助Spline空间插值、Pettitt突变点检验和相关分析等手段对PAR的空间分布、时空演变、突变特征及其可能成因进行了分析。结果表明:① 秦岭南北地区PAR的时间和空间分布特征明显,在空间上呈北高南低的分布格局;在季节分布上,夏季、春季、秋季、冬季依次减小。② 52年间,该地区年PAR整体呈显著下降趋势,下降速率由南向北,由东向西递减;时间变化方面,春季PAR呈现不显著的上升趋势,其余季节均呈下降趋势,夏季减小最快,其次为冬季,秋季最小。③ 该地区89%的站点年PAR存在突变,突变站点中的85%发生于1979-1983年间;夏季89%的站点发生突变,突变站点中的90%发生于1979-1983年间;冬季68%的站点发生突变,但突变时间同步性和一致性较差;春季和秋季突变现象不甚明显。④ 气候变化(风速下降)、城市化进程加快以及工业生产导致的气溶胶增多是导致PAR显著下降的主要原因,而火山爆发引发的气溶胶增加则是PAR波动的主要原因。

Distribution and change of Photosynthetically Active Radiation (PAR) in the northern and southern regions of Qinling Mountains, China

Based on 52-year (1960-2011) daily data from 47 meteorological stations in the northern and southern regions of Qinling Mountains, the annual and seasonal Photosynthetically Active Radiations (PAR) were calculated with equations of Angstrom and FAO Penman-Monteith. The spatial distribution, change trends and their causes were analyzed and detected with spatial analysis method of spline interpolation, Pettitt abrupt change point detection method and correlation analysis between PAR and relative factors. The results were as followed: (1) the PAR became weaker from north part to south part, i.e. from northern region of Qinling Mountains (NQ), to southern region of Qinling Mountains (SQ), to Han River Basin (HB) and to Valleys of Ba and Wu Mountain Areas (VBW). PAR in summer was the highest, followed by spring, autumn and winter. The distribution of PAR in spring, autumn and winter showed the same spatial pattern as annual PAR, but in summer, PAR in NQ is also the highest, then HB and VBW, and SQ being the lowest one. (2) PAR declined significantly in past 52a, the declining rates became smaller from south and east part to north and west part of this region. Except for an insignificant increase in spring, PAR decreased in other seasons, and the rate in summer was fastest, followed by that in winter and autumn. The maximum and minimum PAR appeared in 1960s-1970s and 2000s respectively in spring, summer and autumn. There were almost half of stations showing an increase of PAR mainly in west and central parts, and the other half stations showing decrease in spring. PAR of 79% of stations decreased in autumn, and the increasing stations were also located in west and central parts. PAR in summer and winter declined in most stations, and the decreasing rate was bigger in south part of Qingling Mountains than in north part. (3) 89% of stations had abrupt change points of yearly and summer PAR, and about 85% and 90% of them happened between 1979 and 1983, respectively. There were no obvious abrupt change points in spring or autumn. (4) Climate change (wind speed declining), fast urbanization and more aerosol emission from industrial production were the main reasons for the continuous decline of PAR, and the aerosol emitted from volcanoes was the main reason for fluctuation of PAR.