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的角度，对东京地区斑块状斜坡森林冷空气供应的观测进行了研究。在坡地森林中，夜间冷空气排放比平坦的绿色空间早。绿色空间的宽度至少为100 m，以便冷空气排入城区。当坡林宽度大于200 m时，冷空气必然向外流入周围的建筑物区。这是冷空气过境排放的充分必要条件。即使是较小的绿色空间，也有冷空气的产生，只有在陡坡上才保持斑块状的小森林的降温效果受到限制。

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.