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Nakayama, Hiromasa; Takemi, Tetsuya*; Nagai, Haruyasu
Journal of Applied Meteorology and Climatology, 50(8), p.1692 - 1712, 2011/08
Times Cited Count：38 Percentile：66.80(Meteorology & Atmospheric Sciences)This paper describes the applicability of roughness-length and drag-force approaches of mesoscale meteorological models to actual urban areas. We first investigated building morphological characteristics. Then, we performed large-eddy simulations (LESs) of turbulent flows over building arrays with various surface geometries that are characterized by a wide range of values for not only roughness density and but also building height variability. Then, we evaluated the aerodynamic roughness parameters such as roughness length and drag coefficient for central Tokyo area using the LES results. The values of roughness length and drag coefficient as a function of both roughness length and building height variability is comparable to those in the previous studies. The roughness aerodynamic parameters as a function of roughness length and drag coefficient obtained from our LES results are useful to incorporate the urban effects into weather forecasting models.
Katata, Genki; Nagai, Haruyasu; Wrzesinsky, T.*; Klemm, O.*; Eugster, W.*; Burkard, R.*
Journal of Applied Meteorology and Climatology, 47(8), p.2129 - 2146, 2008/08
Times Cited Count：31 Percentile：57.71(Meteorology & Atmospheric Sciences)A land surface model including cloud water deposition to vegetation was developed to better predict water exchanges between biosphere and atmosphere. High performance of our new model was confirmed and it provided a better prediction of measured cloud water flux than the commonly used model. Simple linear relationships between wind speed and deposition velocity (
) were found. Numerical experiments were performed to study the influences of leaf shapes (needle and broad leaves) and canopy structure (Leaf area index (LAI) and canopy height) on . Broad leaves with small sized leaves can capture larger amounts of cloud water than needle leaves. From the analyses of conductances at given Leaf Area Density (LAD), we found that trees whose LAD 
0.1 m
m
are the most efficient structures for cloud water deposition. A simple expression for the slope of against LAD obtained from the experiments can be useful to predict cloud water deposition.
exchange processes into a multilayer atmosphere-soil-vegetation modelNagai, Haruyasu
Journal of Applied Meteorology, 44(10), p.1574 - 1592, 2005/10
This paper describes the incorporation of CO exchange processes into an atmosphere-soil-vegetation model SOLVEG and examination of its sensitivity and impact of its stomatal resistance calculation on the latent heat flux over a winter wheat field. The model framework for the heat and water exchanges between the atmosphere and ground surface was validated in the previous papers (Nagai 2002, 2003). In this study, CO exchange processes are incorporated in the model and the performance is examined. In the test calculation, the model simulated the CO flux at 2 m above the ground well as a whole. A sensitivity test to clarify uncertainties for the model settings and parameters showed that the CO production in the soil is the most important factor for the CO calculation. Also, the impact of the CO processes on the latent heat flux is discussed. The results indicate that the new model is effective and preferable to study surface exchanges of heat and water as well as CO.
Komatsu, Teruhisa; Adachi, Takeo
Journal of Applied Meteorology, 42(9), p.1330 - 1334, 2003/09
no abstracts in English
Nagai, Haruyasu
Journal of Applied Meteorology, 42(3), p.434 - 451, 2003/03
This paper describes the improvement of an atmosphere-soil-vegetation model and the validation of the new model by observation. In the previous performance test using measured data, some limitations were revealed in the schemes for the canopy radiation transmission and the stomatal resistance calculation, and are improved in this study. By these improvements, the observed albedo and latent heat flux are simulated more properly than before. Results of comparisons between calculations and observations for a winter wheat field and a grassland indicate that the predictability and applicability are improved by the introduction of the new schemes.
Nagai, Haruyasu
Journal of Applied Meteorology, 41(2), p.160 - 176, 2002/02
no abstracts in English
Ishikawa, Hirohiko
Journal of Applied Meteorology, 34(7), p.1653 - 1665, 1995/07
no abstracts in English
Ishikawa, Hirohiko
Journal of Applied Meteorology, 33(6), p.733 - 743, 1994/06
no abstracts in English
