Variation on PAR to global solar radiation ratio along altitude gradient in Naeba Mountain
Variation on PAR to global solar radiation ratio along altitude gradient in Naeba Mountain
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DOI：
10.1007/s00704-005-0220-6
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发表时间：
2007
影响因子：
3.4
通讯作者：
Quan Wang;Y. Kakubari;M. Kubota;J. Tenhunen
中科院分区：
文献类型：
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作者：
Quan Wang;Y. Kakubari;M. Kubota;J. Tenhunen
利用1999-2001年的观测资料，研究了日本苗场山不同海拔沿着3个观测点不同时间尺度的光合有效光子通量（Qp）与总太阳辐射（Rs）的比值。有史以来报告的比率的最低值被发现在每小时和每日规模的所有网站。一个类似的轻微的昼夜模式，发现所有网站的基础上每月平均每小时的比值。然而，不同的网站表现出不同的季节课程。在晴天和多云天气条件下，每小时的Qp/R都有显著的高度依赖性（t检验，P < 0.001）。在晴天条件下，每小时Qp/Rs随海拔升高呈递增趋势，平均速率为3.6%/km。900 m以下的增长率（8.8%/km）比900 m以上的增长率（0.7%/km）更显著。在多云天气条件下，小时Qp/Rs随海拔高度的变化趋势相反。每小时Qp/Rs从550 m下降到1500 m，每km下降率为1.8%。同样，900米以下也出现了大幅下降，每公里下降4.2%，而900米以上每公里下降0.2%。虽然在晴天条件下，每日Qp/Rs也有相同的趋势，但其统计学意义不如每小时Qp/Rs显著（t检验，P < 0.021）。在晴朗天气条件下，Qp/Rsat的增长率接近于小时速率，但在900 m以下，增长率降低到小时速率的一半（4.7%/km）。900 m以上的增长率为2.7%/km。另一方面，在多云天气条件下，每日观察到统计学显著的海拔效应（t检验，P < 0.002）。发现它沿高度梯度沿着迅速下降。其原因是由于900 m以下的下降率较大（每km 12.4%）。但与小时Qp/Rs相似，在多云天气条件下，在900米以上，发现日Qp/Rs的下降率很小。这些结果提示在今后的研究中有必要考虑Qp/R的高度依赖性。
We investigated the ratio of photosynthetically active photon flux (Qp) to global solar radiation (Rs) at three sites along different altitudes in Naeba Mountain, Japan at various temporal scales based on 3 years measurement data (1999–2001). The lowest values of the ratio ever reported were found for all sites on both an hourly and a daily scale. A similar slight diurnal pattern was found for all sites based on the monthly mean hourly values of the ratio. However, different sites exhibited different seasonal courses. Statistically significant altitude dependencies were found for the hourlyQp/Rsunder both clear and cloudy weather conditions (t-test, P < 0.001). For clear weather conditions, the hourlyQp/Rsexhibited an increasing trend with altitude at an average rate of 3.6% per km. The increasing rate was more noticeable below 900 m (8.8% per km) than above (0.7% per km). The inverse trend was found for hourlyQp/Rswith the altitude under cloudy weather conditions. The hourlyQp/Rsdecreased from 550 m to 1500 m at a rate of 1.8% per km. Again, a major decrease occurred below 900 m, which had the rate of 4.2% per km, compared with 0.2% per km over 900 m. Although the same tendencies were noted for dailyQp/Rs, under clear sky conditions, they were not as statistically significant as the hourly counterpart (t-test, P < 0.021). The increasing rate ofQp/Rsat this scale under clear weather conditions was near that of the hourly rate, but below the 900 m rate was reduced to near half of the hourly rate (4.7% per km). And the rate over 900 m increased to 2.7% per km. On the other hand, statistically significant altitude effect was noted for the daily under cloudy weather conditions (t-test, P < 0.002). A rapidly decreasing rate was found for it along the altitude gradient. The reason was due to the large decreasing rate below 900 m (12.4% per km). But again similar to the hourlyQp/Rs, a very small decreasing rate of dailyQp/Rswas found over 900 m under cloudy weather conditions. These results suggest the necessity of considering the altitude dependency ofQp/Rsin future studies.