scholarly journals Evaluation of Profiles of Standard Deviation of Vertical Wind in the Urban Area of Rome: Performances of Monin–Obukhov Similarity Theory Using Different Scaling Variables

2021 ◽  
Vol 13 (15) ◽  
pp. 8426
Author(s):  
Armando Pelliccioni ◽  
Livia Grandoni ◽  
Annalisa Di Bernardino
Keyword(s):  
Standard Deviation ◽  
Urban Areas ◽  
Similarity Theory ◽  
Sonic Anemometer ◽  
Pollutant Dispersion ◽  
Vertical Wind ◽  
Complex Flow ◽  
Flow Distortion ◽  
Scaling Variables ◽  
Flux Layer

The parametrizations of meteorological variables provided by the Monin–Obukhov similarity theory (MOST) is of major importance for pollutant dispersion assessment. However, the complex flow pattern that characterizes the urban areas limits the applicability of the MOST. In this work, the performance of different existing parametrizations of the standard deviation of vertical wind velocity were tested in the city of Rome. Results were compared with experimental data acquired by a sonic detection and ranging (SODAR) and a sonic anemometer. Different scaling variables estimated from the anemometer data by considering two coordinate systems—one aligned with the geodetic reference frame and the other following the flow streamlines—were used to evaluate the effects of flow distortion due to the presence of buildings. Results suggest that the MOST parametrizations perform better if the scaling variables obtained using the coordinate system following the flow streamlines are used. This estimation of the scaling variables would make it possible to overcome the difficulties in conducting measurements of turbulent fluxes, either at different altitudes or even in the constant flux layer.

scholarly journals Comparison of turbulence measurements by a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar

2020 ◽  
Vol 13 (2) ◽  
pp. 969-983 ◽  
Author(s):  
Matthias Mauder ◽  
Michael Eggert ◽  
Christian Gutsmuths ◽  
Stefan Oertel ◽  
Paul Wilhelm ◽  
...  
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Friction Velocity ◽  
Sonic Anemometer ◽  
Vertical Wind ◽  
Doppler Lidar ◽  
Flow Distortion ◽  
Sonic Anemometers ◽  
Vertical Wind Speed ◽  
Standard Deviations

Abstract. Accurate measurements of turbulence statistics in the atmosphere are important for eddy-covariance measurements, wind energy research, and the validation of atmospheric numerical models. Sonic anemometers are widely used for these applications. However, these instruments are prone to probe-induced flow distortion effects, and the magnitude of the resulting errors has been debated due to the lack of an absolute reference instrument under field conditions. Here, we present the results of an intercomparison experiment between a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar, which is inherently free of any flow distortion. This novel remote sensing instrument has otherwise very similar spatial and temporal sampling characteristics to the sonic anemometer and hence served as a reference for this comparison. The presented measurements were carried out over flat homogeneous terrain at a measurement height of 30 m. We provide a comparative statistical analysis of the resulting mean wind velocities, the standard deviations of the vertical wind speed and the friction velocity and investigate the reasons for the observed deviations based on the turbulence spectra and co-spectra. Our results show an agreement of the mean wind velocity measurements and the standard deviations of the vertical wind speed with a comparability of 0.082 and 0.020 m s−1, respectively. Biases for these two quantities were 0.003 and 0.012 m s−1, respectively. Slightly larger differences were observed for friction velocity. Analysis of the corresponding co-spectra showed that the CSAT3B underestimates this quantity systematically by about 3 % on average as a result of co-spectral losses in the frequency range between 0.1 and 5 s−1. We also found that an angle-of-attack-dependent transducer-shadowing correction does not improve the agreement between the CSAT3B and the Physikalisch-Technische Bundesanstalt (PTB) lidar effectively.

scholarly journals Comparison of turbulence measurements by a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar

2019 ◽  
Author(s):  
Matthias Mauder ◽  
Michael Eggert ◽  
Christian Gutsmuths ◽  
Stefan Oertel ◽  
Paul Wilhelm ◽  
...  
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Friction Velocity ◽  
Sonic Anemometer ◽  
Vertical Wind ◽  
Doppler Lidar ◽  
Flow Distortion ◽  
Sonic Anemometers ◽  
Vertical Wind Speed ◽  
Standard Deviations

Abstract. Accurate measurements of turbulence statistics in the atmosphere are important for eddy-covariance measurements, wind energy research, and the validation of atmospheric numerical models. Sonic anemometers are widely used for these applications. However, these instruments are prone to probe-induced flow distortion effects, and the magnitude of the resulting errors has been debated due to the lack of an absolute reference instrument under field conditions. Here, we present the results of an intercomparison experiment between a CSAT3B sonic anemometer and a high-resolution bistatic Doppler lidar, which is inherently free of any flow-distortion. This novel remote sensing instrument has otherwise very similar spatial and temporal sampling characteristics as the sonic anemometer and hence served as a reference for this comparison. The presented measurements were carried out over flat homogeneous terrain, at a measurement height of 30 m. We provide a comparative statistical analysis of the resulting mean wind velocities, the standard deviations of the vertical wind speed and the friction velocity and investigate the reasons for the observed deviations based on the turbulence spectra and cospectra. Our results show a very good agreement of the mean wind velocity measurements and the standard deviations of the vertical wind speed, with comparabilities of 0.082 and 0.017 m s−1, respectively. Biases for these two quantities were very low, being smaller than 0.01 m s−1, which corresponds to about 1 % in relative terms. Slightly larger differences were observed for friction velocity. Analysis of the corresponding cospectra showed that the CSAT3B underestimates this quantity systematically by about 3 % on average as a result of too steep a drop-off in the inertial sub-range. We also found that an angle-of-attack dependent transducer-shadowing correction does not improve this agreement effectively because it leads to an artificial correlation between the three wind components and therefore severely distorts the shape of the cospectra.

scholarly journals Improved Wind and Turbulence Measurements Using a Low-Cost 3-D Sonic Anemometer at a Low-Wind Site

2008 ◽  
Vol 2 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Brent M. Bowen
Keyword(s):  
Standard Deviation ◽  
Wind Direction ◽  
Sonic Anemometer ◽  
Vertical Wind ◽  
Wind Speeds ◽  
Low Wind Speeds ◽  
Mechanical Sensors ◽  
Wind Vane ◽  
Cup Anemometer ◽  
Propeller Anemometer

A year of data from sonic anemometer and mechanical wind sensors was analyzed and compared at a low-wind site. Results indicate that 15-minute average and peak 1-second wind speeds (u) from the sonic agree well with data derived from a co-located cup anemometer over a wide range of speeds. Wind direction data derived from the sonic also agree closely with those from a wind vane except for very low wind speeds. Values of standard deviation of longitudinal wind speed (σu) and wind direction fluctuations (σø) from the sonic and mechanical sensors agree well for times with u > 2 ms-1 but show significant differences with lower u values. The most significant differences are associated with the standard deviation of vertical wind fluctuations (σw): the co-located vertical propeller anemometer yields values increasingly less than those measured by the sonic anemometer as u decreases from 2.5 approaching 0 ms-1. The combination of u over-estimation and under-estimation of σw from the mechanical sensors at low wind speeds causes considerable underestimation of the standard deviation of vertical wind angle fluctuations (σø), an indicator of vertical dispersion. Calculations of σø from sonic anemometer measurements are typically 5° to 10° greater than from the mechanical sensors when the mechanical instruments indicate that σø < 5° or so. The errors with the propeller anemometer, cup anemometer and wind vane, caused by their inability to respond to higher frequency (smaller scale) turbulent fluctuations, can therefore lead to large (factors of 2 to 10 or more) errors in both the vertical and horizontal dispersion during stable conditions with light winds. The sonic anemometer clearly provides more accurate and reliable wind data than the mechanical wind sensor with u < 2.5 ms-1

scholarly journals Review on pollutant dispersion in urban areas-part A: Effects of mechanical factors and urban morphology

2021 ◽  
Vol 190 ◽  
pp. 107534
Author(s):  
Zhengtong Li ◽  
Tingzhen Ming ◽  
Shurong Liu ◽  
Chong Peng ◽  
Renaud de Richter ◽  
...  
Keyword(s):  
Urban Areas ◽  
Pollutant Dispersion ◽  
Urban Morphology ◽  
Mechanical Factors

scholarly journals HEAVY SMOKING

2012 ◽  
Vol 19 (04) ◽  
pp. 433-435
Author(s):  
MUMTAZ ALI SHAIKH ◽  
DUR-E- YAKTA ◽  
DARGAHI SHAIKH
Keyword(s):  
Standard Deviation ◽  
Urban Areas ◽  
Sampling Technique ◽  
Serum Lipoprotein ◽  
High Density Lipoproteins ◽  
Lipid Levels ◽  
Serum Triglycerides ◽  
Heavy Smoking ◽  
Female Ratio ◽  
Heavy Smokers

Objective: This study is conducted to observe the serum lipoprotein alterations in chronic heavy smokers in LUMHS Sindh. Study Design: Analytical study Material and Methods: It was conducted on 60 non obese adult smokers, both sexes, who smoked more than twenty cigarettes or beeries a day regularly for more than five years. All the participants were current smokers. Sampling technique was simple random technique. Setting: The study was conducted in outdoor department of LUMHS Jamshoro/Hyderabad. Period: Jan 2010 to Jan 2011. Eighteen hours fasting blood sample was sent for lipid studies. Lipids studied were serum cholesterol, serum triglycerides, high density lipoproteins and low density lipoproteins. For control values ATP 3 guidelines were used. Statistics: Mean of statistical values was calculated with standard deviation and variance in standard deviation. Results obtained were analyzed by SPSS 11. Results: Age of the patients was 25-70 years. Mean age was 47.81±12.96 years. Median age was 50 years. Male/ female ratio was 45/15. Patients were from both rural and urban areas. Mean duration of smoking was 25.5±9.15 years. The study carried out on 60 chronic heavy smokers, showed deranged lipid levels as: Total cholesterol mean 237.57 mg/dl ±37.89; TG mean 203.76 mg/dl ±47.08; LDL-C mean 158.62 mg/dl ±17.25; HDL-C mean 29.67 mg/dl ±3.12. Results are shown in Table No I. Conclusions: Our study concluded at LUMHS showed that by continuous heavy smoking the serum lipid levels get deranged.

scholarly journals Application of parametric speakers to radio acoustic sounding system

2019 ◽  
Vol 12 (10) ◽  
pp. 5699-5715 ◽  
Author(s):  
Ahoro Adachi ◽  
Hiroyuki Hashiguchi
Keyword(s):  
Standard Deviation ◽  
Temperature Difference ◽  
Acoustic Waves ◽  
Urban Areas ◽  
Vertical Profile ◽  
Wind Profiler ◽  
Acoustic Beam ◽  
Acoustic Sounding ◽  
Accuracy And Precision ◽  
Virtual Temperature

Abstract. In this study, a wind profiler with a radio acoustic sounding system (RASS) and operational radiosonde measurements were used to investigate the technical practicability and reliability of using parametric speakers to measure the vertical profile of virtual temperature. Characteristics of parametric speakers include high directivity and very low side lobes, which are preferable for RASS, especially those operating in urban areas. The experiments were conducted on fine days with light winds to mitigate the effects of the horizontal and vertical components of wind on acoustic waves used for RASS. The results of this study indicated that, although parametric speaker RASS is susceptible to horizontal winds due to the narrower acoustic beam, bias and standard deviation of parametric speaker RASS versus radiosonde virtual temperature difference (0.1 ∘C, 0.4 ∘C) were close to those from acoustic speakers (0.0 ∘C, 0.4 ∘C). In addition, when compared with acoustic speaker RASS, the values for the parametric speaker RASS were even smaller (0.1 ∘C, 0.2 ∘C). Based on these results, it is concluded that the parametric speaker RASS has accuracy and precision comparable with acoustic speaker RASS despite its high directivity of sound.

scholarly journals Micrometeorological Modeling of Radiative and Convective Effects with a Building-Resolving Code

2011 ◽  
Vol 50 (8) ◽  
pp. 1713-1724 ◽  
Author(s):  
Yongfeng Qu ◽  
Maya Milliez ◽  
Luc Musson-Genon ◽  
Bertrand Carissimo
Keyword(s):  
Urban Areas ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Pollutant Dispersion ◽  
Urban Setting ◽  
Dynamical Model ◽  
Neutral Atmosphere ◽  
Atmospheric Flow ◽  
Ongoing Work ◽  
The One

AbstractIn many micrometeorological studies with computational fluid dynamics, building-resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. To take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, a three-dimensional (3D) atmospheric radiative scheme has been developed in the atmospheric module of the Code_Saturne 3D computational fluid dynamic model. On the basis of the discrete ordinate method, the radiative model solves the radiative transfer equation in a semitransparent medium for complex geometries. The spatial mesh discretization is the same as the one used for the dynamics. This paper describes ongoing work with the development of this model. The radiative scheme was previously validated with idealized cases. Here, results of the full coupling of the radiative and thermal schemes with the 3D dynamical model are presented and are compared with measurements from the Mock Urban Setting Test (MUST) and with simpler modeling approaches found in the literature. The model is able to globally reproduce the differences in diurnal evolution of the surface temperatures of the different walls and roof. The inhomogeneous wall temperature is only seen when using the 3D dynamical model for the convective scheme.

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