Aerodynamic drag coefficient and roughness length for three seasons over a tropical western Indian station

Patil, M. N.

doi:10.1016/j.atmosres.2005.10.005

Cited by 23 publications

(23 citation statements)

References 21 publications

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“…The larger values of C D were reported for unstable conditions (ζ ranging from −0.5 to 0) and C D under neutral stability, was 0.0205 and 0.0174 for south-west monsoon and winter conditions, respectively (Patil 2006). These magnitudes are consistent with the magnitude reported in this study.…”

Section: Drag Coefficient Frictional Velocity and Wind Speed In Diffsupporting

confidence: 82%

“…Also, an unsystematic (scatter) variation of C D with wind speed has been reported from tropical (Kusuma et al 1996;Patil 2006) and mid-latitudinal (Wen et al 2005;Suzuki et al 2014) regions. These variations, which is either systematic or unsystematic, appear to be site specific as every site is characterised by different soil and vegetation properties and other regional climatic factors.…”

Section: Drag Coefficient Frictional Velocity and Stability In Low-mmentioning

confidence: 99%

“…On few occasions, it is seen that the wind direction changed drastically and during this change, Z O increased 3-4 times. In an earlier study (Patil 2006), over the homogeneous terrain, C D and Z O were also greater in low winds, however, over the heterogeneous terrain C D and Z O show large variation (Miao and Ji 1996). Claus et al (2012) observed that C D and the Z O were highly dependent on wind direction.…”

Section: Frictional Velocity and Roughness Length With The Wind Direcmentioning

confidence: 99%

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The influence of wind speed on surface layer stability and turbulent fluxes over southern Indian peninsula station

et al. 2016

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Surface to atmosphere exchange has received much attention in numerical weather prediction models. This exchange is defined by turbulent parameters such as frictional velocity, drag coefficient and heat fluxes, which have to be derived experimentally from high-frequency observations. High-frequency measurements of wind speed, air temperature and water vapour mixing ratio (eddy covariance measurements), were made during the Integrated Ground Observation Campaign (IGOC) of Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) at Mahabubnagar, India (16 • 44 N, 77 • 59 E) in the south-west monsoon season. Using these observations, an attempt was made to investigate the behaviour of the turbulent parameters, mentioned above, with respect to wind speed. We found that the surface layer stability derived from the Monin-Obukhov length scale, is well depicted by the magnitude of wind speed, i.e., the atmospheric boundary layer was under unstable regime for wind speeds >4 m s −1 ; under stable regime for wind speeds <2 m s −1 and under neutral regime for wind speeds in the range of 2-3 m s −1 . All the three stability regimes were mixed for wind speeds 3-4 m s −1 . The drag coefficient shows scatter variation with wind speed in stable as well as unstable conditions.

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Section: Drag Coefficient Frictional Velocity and Wind Speed In Diffsupporting

confidence: 82%

Section: Drag Coefficient Frictional Velocity and Stability In Low-mmentioning

confidence: 99%

Section: Frictional Velocity and Roughness Length With The Wind Direcmentioning

confidence: 99%

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The influence of wind speed on surface layer stability and turbulent fluxes over southern Indian peninsula station

et al. 2016

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“…총체 전달 계수들의 오차는 지표면 플럭스 산출 에 비례적인 오차를 야기하고 대기수치모델은 이러한 오 차에 민감하기 때문에 정확한 총체 전달 계수 결정이 필 요하다 (Patil, 2006;Zhang 등, 2011). 해양 위에서 비행 기 관측으로 산출한 운동량 플럭스, 잠열 플럭스, 수증기, 온위, 풍속을 이용하여 추정한 총체 전달 계수에 포함된 오차는 대기 안정도에 크게 의존하였다 (Greenhut, 1982).…”

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Estimation of Atmospheric Turbulent Fluxes by the Bulk Transfer Method over Various Surface

Kim¹,

Kwon

Kang³

2014

Journal of Environmental Science International

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The momentum flux and the sensible heat flux were measured with the scintillometers and ultrasonic anemometers at 6 sites of which surface characteristics like roughness length and zero-displacement are different each other. We estimated the momentum flux and the sensible heat flux based on the bulk transfer method with the drag coefficient and the heat transfer coefficient calculated from the temperature and wind speed at two heights. The variation of bulk transfer coefficients showed a remarkable difference depending on the atmospheric stability which is less influenced by the zero-displacement than the roughness length. The estimated sensible heat fluxes were in good agreement with those measured at 3 m, showing 23.7 Wm -2 of the root mean square error that is less than 10% of its maximum. Since the estimated momentum flux is not only effected by drag coefficient but also by wind speed square, the determination of wind speed in the bulk transfer method is critical.

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“…This parameter also depends on the surface-air temperature difference and atmospheric conditions. Therefore, z om is affected by the integrated effects of aerodynamic and thermodynamic factors and rough elements, which means that z om is actually a parameter varying with wind speed, wind direction, terrain, atmospheric stratification, and LAI (Zhang et al 2004;Patil 2006;Zhou et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Seasonal, Diurnal and Wind-Direction-Dependent Variations of the Aerodynamic Roughness Length in Two Typical Forest Ecosystems of China

Zhou¹,

Sun²,

Ju³

et al. 2012

Terr. Atmos. Ocean. Sci.

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Aerodynamic roughness length (z om ) is an important parameter for reliably simulating surface fluxes. The parameter varies with wind speed, atmospheric stratification, terrain and other factors; however, variations of this parameter are not properly considered in most models, which may result in uncertainties in simulating surface latent heat and sensible heat flux.There have been few studies of the diurnal and wind-direction dependent variations in z om . This study analyzes the seasonal, diurnal and wind-direction-dependent variations in z om calculated from the profile of meteorological data for two forest systems of China, and explores the mechanism underlying these variations.Annually averaged and monthly averaged diurnal variations in z om are obvious and similar at a Changbai Mountain (CBS) site located in northeast China and a Qianyanzhou (QYZ) site located in southeast China. z om is much higher at night than during the day. The diurnal variation in z om is due to a change in atmospheric stratification. The seasonality of z om differs at two sites. z om has sizable seasonal variation and is lower in the leaf-off season than in the growing season at CBS. At QYZ, z om does not have an obvious seasonal pattern. However, at QYZ, the short-term fluctuation is greater than that at CBS. The obvious seasonal variation in z om at CBS is related to the great seasonal change in the leaf area index. The noticeable short-term winddirection-dependent variations in z om at QYZ are attributed to the heterogeneous terrain there.

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Aerodynamic drag coefficient and roughness length for three seasons over a tropical western Indian station

Cited by 23 publications

References 21 publications

The influence of wind speed on surface layer stability and turbulent fluxes over southern Indian peninsula station

The influence of wind speed on surface layer stability and turbulent fluxes over southern Indian peninsula station

Estimation of Atmospheric Turbulent Fluxes by the Bulk Transfer Method over Various Surface

Seasonal, Diurnal and Wind-Direction-Dependent Variations of the Aerodynamic Roughness Length in Two Typical Forest Ecosystems of China

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