Cold air drainage from slope-forests in a city and its availability as a countermeasure against the warming

从尺度、倾斜度、植被类型和城市区域结构等方面对东京地区斑块状斜坡林的冷空气供给进行了研究。在坡地森林中，夜间冷空气排水开始的时间比平坦绿地要早。绿地宽度至少为100米，以保证冷空气进入城区。如果坡林宽度超过200米，冷空气必然会流入周边建成区。这是冷空气跨界排水的充分必要条件。即使是更小的绿地，也能产生冷空气。仅在陡坡上保持斑块状的小森林的降温效果是限制性的。

Observations about the cold-air supply from patchy slope forests in Tokyo were investigated from the viewpoints of a scale, a inclination, the vegetation type and a city area configuration. In the slope forest, nighttime cold air drainage begins earlier than in the flat green space. The width of green space is necessary at least 100m for cold air drainage into city area. If the width of slope forest is more than 200m, cold air surely flows out into surrounding built-up area. This is a necessary and sufficient condition for the cold air drainage across the boundary. Even smaller green space, cold air production was found within it. The cooling effects of small forest which remained patchy in only steep slope were restrictive.