Study on water and heat cycle in forest areas with snow cover

积雪林区水热循环研究

基本信息

批准号：
07306006
负责人：
OHTA Takeshi
金额：
$ 4.03万
依托单位：
Faculty of Agriculture, Iwate University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

The intensive observations were carried out in February 1996 and 1997 at a ash tree forest which was deciduous. The results obtained by these observations were compared to those gotten at evergreen forests. The followings are the new interpretation by this study. (1) Net radiation and sensible heat on the ash tree forest were similar to those on the evergreen forests though there were clear distinctions about canopy conditions. (2) Upward long-wave radiation at the was smaller at the ash tree forest than at the evergreen forest, so differences of albedo among the three forest were set off. Consequently, there was no remarkable difference on net radiation. (3) Zero plane displacement in the ash tree forest was very low and a large part of the canopy layr was effective for heat exchange with atmosphere. Moreover, roughness length was higher at the ash tree forest than at the evergreen forests, so mixing was accelerated. This might be a reason for the fact that sensible heat was similar to each other.About interception on canopies, some new interpretaions were gotten. The followings are the results obtained in Hokkaido. (1) Evaporation was larger in February than during a melting season, because a snow covered period of a canopy was longer. (2) The daily mean values was 0.8 mm/day, and this is twice as large as the values was obtained at an open area. Other results obtained in Tokamachi town where was a warmer and snowy region. (1) The mean interception rate was 2.7-4.2 mm/day. This rate was twice as large as net radiation was. (2) Differences of water equivalent of snow between at a forest and at an open site were mainly caused by snow interception.

1996年2月和1997年2月在落叶白蜡树林中进行了密集观测。将这些观察获得的结果与常绿森林获得的结果进行比较。以下是本研究的新解读。 (1)白蜡树林的净辐射和显热与常绿林相似，但冠层条件存在明显差异。 (2)白蜡树林的向上长波辐射小于常绿林，从而衬托出三种森林反照率的差异。因此，净辐射没有显着差异。 (3)白蜡林的零平面位移很低，大部分冠层能有效地与大气进行热交换。此外，白蜡树森林的粗糙度长度高于常绿森林，因此加速了混合。这可能是显热相似的一个原因。关于冠层拦截，人们得到了一些新的解释。以下是在北海道获得的结果。 (1) 2月份蒸发量比融雪季节大，因为树冠积雪时间较长。 (2) 日平均值为 0.8 毫米/天，是在空旷区域获得的值的两倍。其他结果是在十日町镇获得的，那里是一个温暖多雪的地区。 (1)平均拦截率为2.7-4.2毫米/天。这个比率是净辐射率的两倍。 (2)森林与空地雪水当量的差异主要是由截雪造成的。