Area-Averaged Sensible Heat Flux and a New Method to Determine Zero-Plane Displacement Length over an Urban Surface using Scintillometry

Kanda, Manabu; Moriwaki, Ryo; Roth, Matthias; Oke, T. R.

doi:10.1023/a:1019668424982

Cited by 69 publications

(67 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Surprisingly, the functions developed especially for urban areas generally do not match our data so well as other functions. The function proposed by Kanda et al (2002) systematically underestimates our values by about 0.3, while the function suggested by Roth et al (2006) increases much more rapidly than our data as ζ becomes more negative.…”

Section: The Spectra Of Velocity Componentscontrasting

confidence: 84%

“…Högström 1990;Zhang and Park 1999;Frenzen and Vogel 2001;Su et al 2004;McNaughton 2006;Roth et al 2006). For urbanized areas, the dip observed between ζ = −0.5 and −0.1 is more pronounced in the data from Tokyo and Vancouver analyzed by Kanda et al (2002) than in our studies, whereas data from Basel (Roth et al 2006) show only a slight decrease for measurements above the roof level (z/z H = 1.32). The last square fit of the function defined by Eq.…”

Section: The Spectra Of Velocity Componentscontrasting

confidence: 52%

“…5 is also used in sensible heat-flux estimations with the scintillometer. For rural areas Thiermann and Grassl (1992) suggest c 1 = 3, c 2 = 1, and p 1 = −1, whereas for urban areas Kanda et al (2002) estimate these parameters as c 1 = 10.5, c 2 = 1, and p 1 = −1, and Roth et al (2006) use φ ε = (0.93 − 5.4ζ ) −1.1 − 2ζ , for measurements above rooftops. All these functions differ from that proposed by Wyngaard et al (1971) on the basis of Kansas data,…”

Section: Spectral and Cospectral Characteristicsmentioning

confidence: 99%

See 2 more Smart Citations

Selected Spectral Characteristics of Turbulence over an Urbanized Area in the Centre of Łódź, Poland

Fortuniak

Pawlak

2014

Boundary-Layer Meteorol

View full text Add to dashboard Cite

We present the turbulence spectra and cospectra derived from more than five years of eddy-covariance measurements at two urban sites in Łódź, central Poland. The fast response wind velocity components were obtained using sonic anemometers placed on narrow masts at 37 and 42 m above ground level. The analysis follows Kaimal et al. (Q J R Meteorol Soc 98:563-589, 1972) who established the spectral and cospectral properties of turbulent flow in atmospheric surface layer on the basis of the Kansas experiment. Our results illustrate many features similar to those of Kaimal et al., but some differences are also observed. The velocity (co)spectra from Łódź show a clear inertial subrange with −2/3 slope for spectra and −4/3 slope for cospectra. We found that an appropriate stability function for the non-dimensional dissipation of turbulent kinetic energy calculated from spectra in the inertial subrange differs from that of Kaimal et al., and it can be satisfactorily estimated with the assumption of local equilibrium using standard functions for the non-dimensional shear production. A similar function for the cospectrum corresponds well to Kaimal et al. for unstable and weakly stable conditions. The (co)spectra normalized by their spectral values in the inertial subrange are in general similar to those of Kaimal et al., but they peak at lower frequencies in strongly stable conditions. Moreover, our results do not confirm the existence of a clear "excluded region" at low frequencies for the transition from stable to unstable conditions, for longitudinal and lateral wind components. The empirical models of Kaimal et al. with adjusted parameters fit well to the vertical velocity spectrum and the vertical momentum flux cospectrum. The same type of function should be used for longitudinal and lateral wind spectra because of their sharper peak than occurs for the Kansas data. Finally, it should be stressed that the above relationships are well-defined for averaged values. The results for individual 1-h periods are very scattered and can be significantly different from the generalized functions.

show abstract

Section: The Spectra Of Velocity Componentscontrasting

confidence: 84%

Section: The Spectra Of Velocity Componentscontrasting

confidence: 52%

Section: Spectral and Cospectral Characteristicsmentioning

confidence: 99%

See 1 more Smart Citation

Selected Spectral Characteristics of Turbulence over an Urbanized Area in the Centre of Łódź, Poland

Fortuniak

Pawlak

2014

Boundary-Layer Meteorol

View full text Add to dashboard Cite

show abstract

“…Scintillometry has been in use for several decades; however, it was not until the end of the 1990s that it was used in cities for the first time (Kanda et al 2002). The reliability of scintillometers to provide accurate estimates on surface fluxes has been proven in many different natural or semi-natural areas (e.g.…”

mentioning

confidence: 99%

“…The first measurements with a small-aperture scintillometer (SAS) was performed in Tokyo (Kanda et al 2002), while measurement campaigns using SAS instruments have also taken place in Basel (Roth et al 2006;Salmond et al 2012) and London (Pauscher 2010). The SAS instrument provides fluxes averaged over relatively short paths (up to 250 m), and to obtain fluxes representative of larger areas, a large-aperture scintillometer (LAS) should be used.…”

mentioning

confidence: 99%

Long-term Turbulent Sensible-Heat-Flux Measurements with a Large-Aperture Scintillometer in the Centre of Łódź, Central Poland

Zieliński

Fortuniak

Pawlak

et al. 2018

Boundary-Layer Meteorol

View full text Add to dashboard Cite

We investigate the area-averaged sensible heat flux (Q H ) obtained with a scintillometer along a 3.1-km path length over the city centre of Łódź, Central Poland. The annual cycle of Q H peaks in June but is lower by the middle of summer. In winter, due to a large amount of anthropogenic heat input, Q H remains positive all day long, with positive nighttime fluxes also found during months with frequent cold advection, e.g., June 2010. In the diurnal cycle of this flux, several features specific to urban areas are seen: the peak shifts 1-2 h after noon, the heat flux turns from positive to negative 1-2 h after sunset. In Łódź Q H was observed during inflow from the north and north-west, i.e. from the city centre. As this area is mostly covered with impervious materials, most of the heat exchanged between the ground and the overlying air is in the form of sensible heat flux. Under the conditions of inflow from the east and south-east, the maximum heat flux is approximately 100 W m −2 lower than during the inflow from the city centre, since more vegetation exists to the east and south-east of the scintillometer path. Cold and warm advection are found to be a vital factor in the observed heat-flux variability in the centre of Łódź.

show abstract

Energy and radiation balance of a central European city

Christen

Vogt

2004

Intl Journal of Climatology

391

297

View full text Add to dashboard Cite

Results from an experimental network of seven energy balance stations in and around a European city are presented. The network of micrometeorological stations was part of the Basel Urban Boundary Layer Experiment (BUBBLE) carried out in the city of Basel, Switzerland. Three urban sites provided turbulent flux densities and radiation data over dense urban surfaces. Together with a suburban site and three rural reference sites, this network allowed the simultaneous comparison of urban, suburban, and rural energy balance partitioning during one month of summertime measurements. The partitioning is analysed together with long-term data to evaluate the magnitude of the urban flux density modification, and to document characteristic values in their diurnal and yearly course. Simple empirical relations between flux densities and surface characteristics are presented. The energy balance partitioning is addressed separately for daytime and nocturnal situations. All four components of the surface radiation budget are analysed. Moreover, the vertical flux density divergences within the urban canopy layer are discussed.

show abstract

Area-Averaged Sensible Heat Flux and a New Method to Determine Zero-Plane Displacement Length over an Urban Surface using Scintillometry

Cited by 69 publications

References 32 publications

Selected Spectral Characteristics of Turbulence over an Urbanized Area in the Centre of Łódź, Poland

Selected Spectral Characteristics of Turbulence over an Urbanized Area in the Centre of Łódź, Poland

Long-term Turbulent Sensible-Heat-Flux Measurements with a Large-Aperture Scintillometer in the Centre of Łódź, Central Poland

Energy and radiation balance of a central European city

Contact Info

Product

Resources

About