Correlation of temperature and vertical wind variances with the turbulent heat flux in the atmospheric surface layer is considered. Analytical equations relating minimal possible variances of temperature and vertical wind to the heat flux (in the both positive and negative ranges of its values) are obtained from experimental data. The effect of the measurement height on the parameters of these equations is briefly considered.
Vertical turbulent heat fluxes in the atmospheric surface layer under daytime convection conditions were measured and calculated using model equations. The experimental data needed for the calculations were obtained with ultrasonic anemometers-thermometers and a meteorological temperature profiler. A good agreement between model calculations and experimental data is demonstrated.
The turbulence characteristics that determine changes in the air temperature variance in the atmospheric surface layer are considered. The main experimental material for the analysis was obtained with a sonic weather station set in the atmospheric surface layer (10 m) at a territory with natural landscape. Some episodes observed in the summer and winter seasons are analyzed. It is found that the flows of temperature variance decrease markedly in winter as compared to summer. A pronounced diurnal profile of the studied characteristic was observed in summer and absent in winter.
Air temperature variances under conditions of temperature inversions at the weak vertical heat exchange are estimated. It is shown that the increased temperature variance under these conditions can be associated with horizontal turbulent heat fluxes. The experimental data needed for the calculation were obtained with ultrasonic anemometers-thermometers and a meteorological temperature profiler.
Experimental data on air temperature inversions in the planetary boundary layer are analyzed with the emphasis on events characterized by wide temperature differences between inversion boundaries. Temperature profiles measured in 2020-2021 with MTP-5 meteorological temperature profilometers at two observation sites located in southwestern Siberia (Tomsk) are used. The correlation between the inversion intensity and the wind direction in the atmospheric surface layer is touched.
The derivatives of mixed moments of turbulent and meso-gamma-scale wind vector components with respect to time and spatial coordinates are analyzed. The derivatives are estimated from experimental data obtained at heights of 5 and 10 m. It is shown that meso-gamma-scale variations of the wind field should be necessarily taken into account in problems of predicting the state of the atmospheric surface layer.
The routine monitoring of weather and turbulent characteristics in the atmospheric surface layer at the Basic Experimental Observatory of the Institute of Atmospheric Optics SB RAS revealed some particular cases in the behavior of vertical turbulent heat fluxes Qz at close heights. Atmospheric parameters were monitored with two Meteo-2 ultrasonic weather stations installed at the same tower at heights of 5 and 10 m. There were particular cases that heat fluxes observed simultaneously at heights of 5 and 10 m had different signs, that is, the antiphase effect took place. The cases that the vertical heat flux was negative at a height of 5 m and positive at 10 m (antiphase of Type 1) and that the heat flux was positive at 5 m and negative at 10 m (antiphase of Type 2) were observed. Vertical heat fluxes measured in 2018–2021 are analyzed.
Temperature differences between two observation sites at different heights in the atmospheric boundary layer are considered. Temperature profiles measured in 2020–2021 over an urban territory (Academgorodok, suburbs of Tomsk) and natural landscape (Basic Experimental Observatory of IAO SB RAS) are used. The effect of a heat island, its characteristics and vertical dimension under various conditions are discussed.
The mixed moments of the wind vector components are compared when these components are decomposed into deterministic, meso-gamma-scale, and turbulent parts. The results of wind measurements at heights of 5 and 10 m in August 2021 at a site with natural landscape (large grassy meadow) are used. It is shown that meso-gamma-scale variations of the wind field should necessarily be taken into account in problems of modeling (predicting) the state of the atmospheric surface layer.
Particular cases of the air temperature distributions in the atmospheric boundary layer during formation of an urban heat island (UHI) have been analyzed. For UHI calculations, we used the temperature values measured at the two observations sites spaced by 3 km and located in the Tomsk suburbs (Akademgorodok) and the rural territory (Basic Experimental Observatory of IAO SB RAS). The goal of this study was to reveal and examine the cases of a cold lens covering an urban heat island.
In diagnostics of the atmospheric boundary layer (ABL), it is interesting to study an urban heat island (UHI), in which the air temperature over an urban territory markedly exceeds that outside the city. The aim of our study was to calculate and analyze the difference between temperatures measured at different heights inside and outside the city. The data obtained were used (1) to reveal UHI events, (2) to estimate the vertical dimension of UHI, (3) to analyze the relation of UHI to the local time, temperature gradients in the bottom part of ABL, and wind speed and direction.
Experimental data obtained with MTP-5 temperature profilometers are used to estimate the Brunt–Vaisala frequencies in the atmospheric boundary layer at the territory of Basic Experimental Observatory (BEC) of IAO SB RAS and in Akademgorodok (suburbs of the city of Tomsk). The statistics of these frequencies in different seasons is analyzed.
The statistics of air temperature inversions in the atmospheric boundary layer at the territory of Basic Experimental Observatory (BEC) of IAO SB RAS and in Akademgorodok (suburbs of the city of Tomsk) is analyzed with data of MTP-5 temperature profilometers. Peculiarities of inversion characteristics (temperature gradients, boundaries) in different seasons are discussed.
The dependence of the turbulent kinetic energy in the atmospheric surface layer on the wind velocity is analyzed. This dependence is parametrized by a power functions. Experimental data obtained at heights of 5 and 10 m at territories with natural landscape and at a height of 17 m at an urban territory serve as initial data for the analysis. The results obtained for two years of measurements (2018 and 2019) are processed.
The statistical analysis of contributions from different combinations of pulsations of air temperature and vertical component of the wind to the turbulent heat flux (quadrant analysis) has been performed with the values of these components measured by ultrasonic meteostations (sonic) in the atmospheric surface layer at different sites, different height, and in different time in the summer season.
Fluxes of air temperature in the atmospheric surface layer have been calculated from experimental data obtained with the ultrasonic anemometer-thermometer. Estimates of temperature fluxes of the “turbulent” and “local” scales along three axes of the Cartesian coordinate system in the summer period over an urban territory have been considered. The fluxes observed in the day and night time have been compared.
The relation of the height of intense turbulent heat exchange layer in the atmospheric boundary layer to the air temperature gradients, wind velocity, and turbulent heat flux in the atmospheric surface layer has been analyzed. Experimental data obtained with the sodar, temperature profilometer, and ultrasonic meteostation have been used for the analysis. The emphasis is on the conditions with stable stratification (temperature inversion) in the boundary layer in winter.
Estimates of the radius of spatial coherence of the laser beam in the atmospheric boundary layer are reported. Experimental data obtained with a Volna-4M meteorological acoustic lidar (sodar) were used for the estimates. The main purpose was to draw the diurnal average profile of the coherence radius for different seasons at different levels.
Possible refraction of laser beam simultaneous with the beam broadening due to turbulence in the atmospheric boundary layer is estimated. Experimental data obtained with an MTP-5 meteorological temperature profiler and a Volna-4M sodar are used for the estimation. The main purpose is to separate the cases, when the strong refraction and significant broadening of a laser beam took place simultaneously, and to analyze them.
In the work, we consider estimates of the height of layer of intense turbulent heat exchange in stably stratified atmospheric boundary layer, made with the use of meteorological acoustic radar (sodar). Dependence of this height on temperature gradient is analyzed. Current temperature stratification of the atmosphere in the layer with height up to 1 000 m was determined with the help of МТР-5 meteorological temperature profiler.
Based on experimental data, obtained in the near-ground atmospheric layer with different structures of the underlying surface, we calculated the elements of turbulence anisotropy tensor. Their average values and standard deviations for different conditions of measurements are determined. The effect of regimes of experimental data processing on statistics of elements of anisotropy tensor is considered. A high stability degree of the average values of the tensor components under different conditions is noted.
In the report, the results of analysis of the (second-order) structure tensor of wind velocity components, measured in the near-ground atmospheric layer, are discussed. We considered the main forms and possible parameterization (selection of approximating functions) of structure tensor elements in the range of lags, corresponding to inertial interval of turbulence energy transfer. The parameters of approximating functions are estimated.
The report presents estimates of the interlevel correlation of the wind velocity components from the data of acoustic sensing of the atmospheric boundary layer under different atmospheric conditions. The correlation matrices whose components are correlation moments for different altitude levels are analyzed. The influence of omissions in the initial data arrays on the statistical robustness of estimates of the examined functions is discussed.
The paper discusses the method, possible errors, and results of retrieval of altitudinal-temporal distribution of normalized structure characteristic of temperature fluctuations in the atmospheric boundary layer from measurements by VOLNA-3 sodar owned by Institute of Atmospheric Optics SB RAS.
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