Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.414 IF 5.414
  • IF 5-year value: 5.958 IF 5-year
    5.958
  • CiteScore value: 9.7 CiteScore
    9.7
  • SNIP value: 1.517 SNIP 1.517
  • IPP value: 5.61 IPP 5.61
  • SJR value: 2.601 SJR 2.601
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 191 Scimago H
    index 191
  • h5-index value: 89 h5-index 89
Volume 16, issue 3
Atmos. Chem. Phys., 16, 1809–1822, 2016
https://doi.org/10.5194/acp-16-1809-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 16, 1809–1822, 2016
https://doi.org/10.5194/acp-16-1809-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 16 Feb 2016

Research article | 16 Feb 2016

Impact of an improved WRF urban canopy model on diurnal air temperature simulation over northern Taiwan

Chuan-Yao Lin1, Chiung-Jui Su1, Hiroyuki Kusaka2, Yuko Akimoto2, Yang-Fan Sheng1, Jr-Chuan Huang3, and Huang-Hsiung Hsu1 Chuan-Yao Lin et al.
  • 1Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
  • 2Graduate school of Life and Environmental Sciences, and Center for Computational Sciences, University of Tsukuba, Tsukuba, Japan
  • 3Department of Geography, National Taiwan University, Taipei, Taiwan

Abstract. This study evaluates the impact of urbanization over northern Taiwan using the Weather Research and Forecasting (WRF) Model coupled with the Noah land-surface model and a modified urban canopy model (WRF–UCM2D). In the original UCM coupled to WRF (WRF–UCM), when the land use in the model grid is identified as "urban", the urban fraction value is fixed. Similarly, the UCM assumes the distribution of anthropogenic heat (AH) to be constant. This may not only lead to over- or underestimation of urban fraction and AH in urban and non-urban areas, but spatial variation also affects the model-estimated temperature. To overcome the abovementioned limitations and to improve the performance of the original UCM model, WRF–UCM is modified to consider the 2-D urban fraction and AH (WRF–UCM2D).

The two models were found to have comparable temperature simulation performance for urban areas, but large differences in simulated results were observed for non-urban areas, especially at nighttime. WRF–UCM2D yielded a higher correlation coefficient (R2) than WRF–UCM (0.72 vs. 0.48, respectively), while bias and RMSE achieved by WRF–UCM2D were both significantly smaller than those attained by WRF–UCM (0.27 and 1.27 vs. 1.12 and 1.89, respectively). In other words, the improved model not only enhanced correlation but also reduced bias and RMSE for the nighttime data of non-urban areas. WRF–UCM2D performed much better than WRF–UCM at non-urban stations with a low urban fraction during nighttime. The improved simulation performance of WRF–UCM2D in non-urban areas is attributed to the energy exchange which enables efficient turbulence mixing at a low urban fraction. The result of this study has a crucial implication for assessing the impacts of urbanization on air quality and regional climate.

Publications Copernicus
Download
Short summary
This study evaluated the impact of urbanization over northern Taiwan using the Weather Research and Forecasting (WRF) Model coupled with the Noah land-surface model and a modified urban canopy model (WRF-UCM2D). WRF-UCM2D performed much better than the original UCM coupled with WRF (WRF-UCM) at non-urban stations with a low urban fraction during nighttime. The result of this study has crucial implications for assessing the impacts of urbanization on air quality and regional climate.
This study evaluated the impact of urbanization over northern Taiwan using the Weather Research...
Citation
Final-revised paper
Preprint