Variability of the start of the growing season in Fennoscandia, 1982-2002
Variability of the start of the growing season in Fennoscandia, 1982-2002
复制标题
DOI：
10.1007/s00484-007-0091-x
复制
发表时间：
2007-08-01
影响因子：
3.2
通讯作者：
Tommervik, Hans
中科院分区：
文献类型：
--
作者：
Karlsen, Stein Rune;Solheim, Inger;Tommervik, Hans
芬诺斯坎迪亚的特点是气候多样性很大。区域内不同的气候梯度，植被物候对气候变化的响应可能不同。为了绘制芬诺斯坎迪亚生长季开始（SOS）的年度和空间变异，使用了两个月的GIMMS-NDVI卫星数据集。该数据集的空间分辨率为8 × 8 km(2)，覆盖时间为1982年至2002年。映射是通过对NDVI数据应用特定像素的阈值来完成的。这些阈值是根据桦树（Betula sp.）表面物候数据确定的。然后，我们为每21年制作了基于NDVI的SOS地图。最后，分析了21个气象站的SOS与积雪最后一天的时间差，以及通过不同温度的日期。分析表明，1985年是晚期SOS最极端的年份。就早期SOS而言，1990年是迄今为止最极端的一年。局部地区最早与最近记录的SOS平均相差1个月，海洋地区有较大的变化趋势。结果表明，春季气温每升高1℃，SOS一般会提前5-6天。然而，从海洋性程度来看，有一个明显的趋势，大多数海洋部分的升温1摄氏度大致对应于SOS提前7-9天，而大陆部分的升温幅度不到5天。
Fennoscandia is characterized by a large degree of climatic diversity. Vegetation phenology may respond differently to climate change according to the climatic gradients within the region. To map the annual and spatial variability of the start of the growing season ( SOS) in Fennoscandia, the twice-monthly GIMMS-NDVI satellite dataset was used. The data set has an 8 x 8 km(2) spatial resolution and covers the period from 1982 to 2002. The mapping was done by applying pixel-specific threshold values to the NDVI data. These threshold values were determined form surface phenology data on birch ( Betula sp.). Then, we produced NDVI based maps of SOS for each of the 21 years. Finally, the time differences between the SOS and the last day of snow cover, as well as dates of passing different temperatures, were analyzed for 21 meteorological stations. The analyses showed that 1985 was the most extreme year in terms of late SOS. In terms of early SOS, the year 1990 was by far the most extreme. Locally, the SOS has an average range of 1 month between the earliest and latest recorded SOS, with a trend towards a bigger range in the oceanic parts. The results indicate that a 1 degrees C increase in spring temperatures in general corresponds to an advancement of 5-6 days in SOS. However, there is a clear trend according to the degree of oceanity, with a 1 degrees C increase in the most oceanic parts corresponding roughly to 7-9 days earlier SOS, compared to less than 5 days earlier in the continental parts.