Behavior of the Refractive-Index-Structure Parameter near the Ground*

Wyngaard, J. C.; Izumi, Yutaka; Collins, Stuart A.

doi:10.1364/josa.61.001646

Cited by 359 publications

(173 citation statements)

References 9 publications

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“…Monin-Obukhov similarity theory (MOST) makes it possible to link C 2 T and the areaaveraged sensible heat flux Q H , and first, the temperature scale T * is computed from C 2 T (e.g. Wyngaard et al 1971),…”

Section: Sensible-heat-flux Retrieval From Scintillometer Measurementsmentioning

confidence: 99%

“…The most commonly used forms for the similarity function in Eq. 2 are those of Wyngaard et al (1971); however, a range of parameters can be found in the literature. For unstable conditions, the MOST function has the following form,…”

Section: Sensible-heat-flux Retrieval From Scintillometer Measurementsmentioning

confidence: 99%

“…Andreas ( 1988) adjusted the values for c T 1 = 4.9, c T 2 = 6.1 and c T 3 = 4.9, c T 4 = 2.2, previously given by Wyngaard et al (1971) to reflect κ = 0.4, while De Bruin et al (1993) gave different values i.e. c T 1 = 4.9, c T 2 = 9 and c T 3 = 4.9, c T 4 = 0.…”

Section: Sensible-heat-flux Retrieval From Scintillometer Measurementsmentioning

confidence: 99%

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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

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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.

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Section: Sensible-heat-flux Retrieval From Scintillometer Measurementsmentioning

confidence: 99%

Section: Sensible-heat-flux Retrieval From Scintillometer Measurementsmentioning

confidence: 99%

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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

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“…A large-aperture scintillometer provides the path-averaged refractive index structure parameter (C 2 n ), and together with auxiliary measurements of air temperature, humidity and atmospheric pressure, the temperature structure parameter (C 2 T ) can be calculated. Surface fluxes can then be related to C 2 T via MoninObukhov similarity theory (e.g., Wyngaard et al 1971),…”

Section: Scintillation Method: Sensible Heat-flux Retrievalmentioning

confidence: 99%

“…For LAS, the similarity functions given by Wyngaard et al (1971) are the most commonly used, albeit with different constants (e.g., Andreas 1988; Hill et al 1992;De Bruin et al 1993).The friction velocity u * can be obtained from…”

Section: Scintillation Method: Sensible Heat-flux Retrievalmentioning

confidence: 99%

Influence of Mean Rooftop-Level Estimation Method on Sensible Heat Flux Retrieved from a Large-Aperture Scintillometer Over a City Centre

Zieliński

Fortuniak

Pawlak

et al. 2017

Boundary-Layer Meteorol

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The sensible heat flux (H ) is determined using large-aperture scintillometer (LAS) measurements over a city centre for eight different computation scenarios. The scenarios are based on different approaches of the mean rooftop-level (z H ) estimation for the LAS path. Here, z H is determined separately for wind directions perpendicular (two zones) and parallel (one zone) to the optical beam to reflect the variation in topography and building height on both sides of the LAS path. Two methods of z H estimation are analyzed: (1) average building profiles; (2) weighted-average building height within a 250 m radius from points located every 50 m along the optical beam, or the centre of a certain zone (in the case of a wind direction perpendicular to the path). The sensible heat flux is computed separately using the friction velocity determined with the eddy-covariance method and the iterative procedure. The sensitivity of the sensible heat flux and the extent of the scintillometer source area to different computation scenarios are analyzed. Differences reaching up to 7% between heat fluxes computed with different scenarios were found. The mean rooftop-level estimation method has a smaller influence on the sensible heat flux (−4 to 5%) than the area used for the z H computation (−5 to 7%). For the source-area extent, the discrepancies between respective scenarios reached a similar magnitude. The results demonstrate the value of the approach in which z H is estimated separately for wind directions parallel and perpendicular to the LAS optical beam.

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A vertical DIM lidar for refractive index structure parameter profiles estimation in low‐layer atmosphere

Qiu

Wang

Hou

et al. 2023

Micro & Optical Tech Letters

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This Letter presents an experimental demonstration of a vertical differential image motion (DIM) lidar for calculating the profiles of the low-layer atmospheric refractive index structure parameters. Utilizing the differences between weighting functions, we propose a convenient approach for the realtime estimation of low-layer C n 2 profiles from DIM lidar data. This approach only requires returned fluxes as input, yet it has the intrinsic ability to capture real-time turbulence profiles. Validations against the collected observational data have shown this approach to be computationally inexpensive. The longterm comparisons with micro-thermometers indicate that in such a way vertical DIM lidars can be used for providing not only a general assessment of turbulence effects along the measurement path but turbulence profiles.

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Behavior of the Refractive-Index-Structure Parameter near the Ground*

Cited by 359 publications

References 9 publications

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

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

Influence of Mean Rooftop-Level Estimation Method on Sensible Heat Flux Retrieved from a Large-Aperture Scintillometer Over a City Centre

A vertical DIM lidar for refractive index structure parameter profiles estimation in low‐layer atmosphere

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