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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，在一个落叶的白蜡树森林进行了密集的观测。通过这些观测获得的结果进行了比较，在万年青森林。以下是本研究的新解释。(1)白蜡林的净辐射和感热与万年青林相似，但林冠条件有明显区别。(2)水曲柳林的向上长波辐射小于万年青林，这就造成了三种林分的辐射差异。因此，净辐射没有显著差异。(3)水曲柳林的零平面位移很低，大部分冠层与大气进行有效的热交换。此外，粗糙度长度是较高的白蜡树林比万年青林，所以混合加速。这可能是两者感热相似的原因之一。关于林冠截留，得到了一些新的解释。以下是在北海道获得的结果。(1)2月的蒸发量大于融化季节，因为树冠的积雪期较长。(2)每日平均值为0.8 mm/天，这是在开放区域获得的值的两倍。其他结果在十日町镇，那里是一个温暖和多雪的地区。(1)平均截留率为2.7- 4.2mm/d。这个比率是净辐射的两倍。(2)林下和空旷地雪水当量的差异主要是由积雪截留引起的。