Scaling of turbulence inurban surface layer using boundary layerheight

使用边界层高度缩放城市表层湍流

基本信息

批准号：
22360198
负责人：
MORIWAKI Ryo
金额：
$ 12.23万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2010
资助国家：
日本
起止时间：
2010 至 2012
项目状态：
已结题

项目摘要

The main interest in this study is the relationship between boundary layer height and the urban surface turbulence and energy balance. We investigated the effects of differences in land use on the formation of clouds, using the summer time datasets from the observations of cloud base level, solar radiation, surface heat flux, air temperature and humidity. The followings are main outcomes.Cloud base level over urban area was higher than that over rural area when wind blew along the border of the abrupt change of land use. Solar radiation over urban area tended to be smaller than that over rural area in the afternoon of sunny days. This was demonstrated by the spatial distribution of water vapor and the development of mixing layerestimated from surface heat flux. Absolute humidity in urban area tended to be lower in comparison with that in rural area. Therefore, the urban dew-point temperature also became lower than that in rural area. As a result, the urban lifted condensation level(LCL) was also lower. The spatial difference of LCL qualitatively coincided with that of observed boundary layer. This indicates that the surface water vapor distribution affected the formation of cloud aloft. In addition, the mixing layer height was estimated from the accumulation of surface heat flux. The estimation shows that the convection developed upward beyond LCL and this is more prominent in urban area. The estimation supports the observation where cloud in urban area tended to develop higher than rural area.

这项研究的主要兴趣是边界层高度与城市表面湍流与能量平衡之间的关系。我们使用夏季时间数据集，从云基底水平，太阳辐射，表面热通量，空气温度和湿度中观察到的夏季时间数据集研究了土地使用差异对云形成的影响。以下是主要的结果。城市地区的基本水平高于农村地区的基本水平，当时沿着土地使用的突然变化边界爆炸时。在阳光明媚的日子下午，在城市地区的太阳辐射往往比农村地区的太阳辐射小。这是通过水蒸气的空间分布和从表面热通量中估计的混合的发展来证明的。与农村地区相比，市区的绝对湿度往往较低。因此，城市露点温度也比农村地区低。结果，城市提升的冷凝水平（LCL）也较低。 LCL的空间差异与观察到的边界层的空间差异相吻合。这表明地表水蒸气分布影响了云的形成。另外，从表面热通量的积累中估算了混合层高度。估计表明，对流在LCL之外发展起来，这在市区更为突出。该估计支持观察结果，在该观察结果中，城市地区的云倾向于高于农村地区。