The turbulent transport of heat and water vapour in an unstable atmosphere

Dyer, A. J.

doi:10.1002/qj.49709339809

Cited by 154 publications

(69 citation statements)

References 9 publications

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“…The turbulent fluxes of momentum and sensible heat are calculated by accounting for stability effects and the roughness sublayer (Garratt, 1992). Therein, flux-profile relationships for wind speed and temperature from Cheng and Brutsaert (2005), Businger (1966) or Dyer (1967), andDe Ridder (2010) are used. These flux-profile functions are solved for ζ = z/L iteratively (z is the lowest model layer height above the displacement height and L the Obukhov Length) by establishing a relation involving the bulk Richardson number Ri B (Arya, 2001), and using Ridders (1979) root finding scheme as described in Press et al (1992).…”

Section: Mesoscale Model Description and Set-upmentioning

confidence: 99%

The diurnal evolution of the urban heat island of Paris: a model-based case study during Summer 2006

et al. 2013

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The urban heat island (UHI) over Paris during summer 2006 was simulated using the Advanced Regional Prediction System (ARPS) updated with a simple urban parametrization at a horizontal resolution of 1 km. Two integrations were performed, one with the urban land cover of Paris and another in which Paris was replaced by cropland. The focus is on a five-day clear-sky period, for which the UHI intensity reaches its maximum. The diurnal evolution of the UHI intensity was found to be adequately simulated for this five day period. The maximum difference at night in 2 m temperature between urban and rural areas stemming from the urban heating is reproduced with a relative error of less than 10%. The UHI has an ellipsoidal shape and stretches along the prevailing wind direction. The maximum UHI intensity of 6.1 K occurs at 23:00 UTC located 6 km downstream of the city centre and this largely remains during the whole night. An idealized one-column model study demonstrates that the nocturnal differential sensible heat flux, even though much smaller than its daytime value, is mainly responsible for the maximum UHI intensity. The reason for this nighttime maximum is that additional heat is only affecting a shallow layer of 150 m. An air uplift is explained by the synoptic east wind and a ramp upwind of the city centre, which leads to a considerable nocturnal adiabatic cooling over cropland. The idealized study demonstrates that the reduced vertical adiabatic cooling over the city compared to cropland induces an additional UHI build-up of 25%. The UHI and its vertical extent is affected by the boundary-layer stability, nocturnal low-level jet as well as radiative cooling. Therefore, improvements of representing these boundary-layer features in atmospheric models are important for UHI studies

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Section: Mesoscale Model Description and Set-upmentioning

confidence: 99%

The diurnal evolution of the urban heat island of Paris: a model-based case study during Summer 2006

et al. 2013

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“…These schemes (e.g., Paulson, 1970;Businger et al, 1971;Dyer, 1974;Holtslag and De Bruin, 1988;Beljaars and Holtslag, 1991;Janjić, 1994;Launiainen, 1995;Högström, 1996) are similar to each other, but the differences among them exist due to different observational data and/or mathematical solutions that were used in retrieving the schemes. One commonly used scheme is Businger-Dyer (BD) equation (Businger, 1966;Dyer, 1967). However, the BD equation suppresses fluxes under stable conditions too quickly and is not applicable when the Richardson number exceeds a critical value (Louis, 1979).…”

Section: Introductionmentioning

confidence: 99%

An improved non-iterative surface layer flux scheme for atmospheric stable stratification conditions

Gao

et al. 2014

Geosci. Model Dev.

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Abstract. Parameterization of turbulent fluxes under stably stratified conditions has always been a challenge. Current surface fluxes calculation schemes either need iterations or suffer low accuracy. In this paper, a non-iterative scheme is proposed to approach the classic iterative computation results using multiple regressions. It can be applied to the full range of roughness status 10 ≤ z/z 0 ≤ 10 5 and −0.5 ≤ log(z 0 /z 0h ) ≤ 30 under stable conditions 0 < Ri B ≤ 2.5. The maximum (average) relative errors for the turbulent transfer coefficients for momentum and sensible heat are 12 % (1 %) and 9 % (1 %), respectively.

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“…φ m and φ h are the Monin-Obukhov similarity functions of momentum and temperature. According to Dyer and Hicks (Dyer et al, 1970;Hicks, 1976), their formulae are as follows:…”

Section: Aerodynamic Methodsmentioning

confidence: 99%

The characteristics of the sensible heat and momentum transfer coefficients over the Gobi in Northwest China

Zhang

Barlage

Tian

et al. 2011

Intl Journal of Climatology

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Utilizing the data of the intensive observation period (May-June 2000) of the Dunhuang land-surface process field experiment supported by the 'Atmosphere-land Interactive Field Experiment over Arid Regions of Northwest China(NWC-ALIEX)', the bulk momentum transfer coefficient (C d ) and the bulk sensible heat transfer coefficient (C h ) between the surface and the atmosphere over the arid Gobi Desert region are determined using three different methods. The results indicate that these coefficients, especially the means, are the same order of magnitude. The influence of the building near the observational station on the results is significant. When the building effect exists, the diurnal variation of the atmospheric bulk transfer coefficients and the bulk Richardson number are irregular. After the building effect is eliminated through analysing the wind direction, the bulk Richardson number and the range of the typical values of the bulk transfer coefficients over the Gobi are obtained. The diurnal variations of the bulk transfer coefficients are smoother than that without the building affect. The bulk transfer coefficients are larger in the daytime than in the nighttime. It is also worth noting that the variations of the bulk transfer coefficients and the bulk Richardson number are just opposite in phase, and that the bulk transfer coefficient for sensible heat flux is more related to the bulk Richardson number than that for momentum flux. The results are more reasonable than that after removing the building effect. The relation between the bulk transfer coefficients is also discussed.

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The turbulent transport of heat and water vapour in an unstable atmosphere

Cited by 154 publications

References 9 publications

The diurnal evolution of the urban heat island of Paris: a model-based case study during Summer 2006

The diurnal evolution of the urban heat island of Paris: a model-based case study during Summer 2006

An improved non-iterative surface layer flux scheme for atmospheric stable stratification conditions

The characteristics of the sensible heat and momentum transfer coefficients over the Gobi in Northwest China

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