2012 Fiscal Year Final Research Report
Scaling of turbulence inurban surface layer using boundary layerheight
| Project/Area Number |
22360198
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hydraulic engineering
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| Research Institution | Ehime University |
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Principal Investigator |
MORIWAKI Ryo 愛媛大学, 大学院・理工学研究科, 准教授 (10302952)
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| Project Period (FY) |
2010 – 2012
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| Keywords | 境界層 / 乱流 / 都市気象 / フラックス / ヒートアイランド / 雲 |
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| Research Abstract |
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.
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