Turbulence characteristics of an atmospheric surface layer over a coastal mountain area were investigated under different coordinate frames. Performances of three methods of coordinate rotation： double rotation （DR...Turbulence characteristics of an atmospheric surface layer over a coastal mountain area were investigated under different coordinate frames. Performances of three methods of coordinate rotation： double rotation （DR）, triple rotation （TR）, and classic planar-fit rotation （PF） were examined in terms of correction of eddy covariance flux. Using the commonly used DR and TR methods, unreasonable rotation angles are encountered at low wind speeds and cause significant run-to-run errors of some turbulence characteristics. The PF method rotates the coordinate system to an ensemble-averaged plane, and shows large tilt error due to an inaccurate fit plane over variable terrain slopes. In this paper, we propose another coordinate rotation scheme. The observational data were separated into two groups according to wind direction. The PF method was adapted to find an ensemble-averaged streamline plane for each group of hourly runs with wind speed exceeding 1.0 m s-1. Then, the coordinate systems were rotated to their respective best- fit planes for all available hourly observations. We call this the PF10 method. The implications of tilt corrections for the turbulence characteristics are discussed with a focus on integral turbulence characteristics, the spectra of wind-velocity components, and sensible heat and momentum fluxes under various atmospheric stabilities. Our results show that the adapted application of PF provides greatly improved estimates of integral turbulence characteristics in complex terrain and maintains data quality. The comparisons of the sensible heat fluxes for four coordinate rotation methods to fluxes before correction indicate that the PF10 scheme is the best to preserve consistency between fluxes.展开更多
By using the meteorological data in the pollution boundary layer which was observed in two ground observation sites:coast and land in the river outlet area of Grand Liao River during January-February in 2007,the daily...By using the meteorological data in the pollution boundary layer which was observed in two ground observation sites:coast and land in the river outlet area of Grand Liao River during January-February in 2007,the daily change characteristics of pollute boundary layer in winter in the area were discussed. The results showed that the pollute boundary layer in the river outlet area of Grand Liao River was affected by the sea and land. In the certain weather condition,maybe the sea-land breeze appeared in the low altitude which was below 200 m in the coastal zone. The stability change in the different height in the coastal zone was more stable than in the land zone,and the wind field change in the area was mainly in 300 m low altitude. At night,the temperature inversion often appears in the area,and the thickness of temperature inversion layer is stably during 200-300 m. The thermal internal boundary layer penetrated deeply into the land about 10 km,and the height could reach 800 m. The atmospheric diffusion ability in the coastal area was weaker and stronger in the land area.展开更多
Classical turbulent K closure theory of the atmospheric boundary layer assumes that the vertical turbulent transport flux of any macroscopic quantity is equivalent to that quantity's vertical gradient transport fl...Classical turbulent K closure theory of the atmospheric boundary layer assumes that the vertical turbulent transport flux of any macroscopic quantity is equivalent to that quantity's vertical gradient transport flux. But a cross coupling between the thermodynamic processes and the dynamic processes in the atmospheric system is demonstrated based on the Curier-Prigogine principle of cross coupling of linear thermodynamics. The vertical turbulent transportation of energy and substance in the atmospheric boundary layer is related not only to their macroscopic gradient but also to the convergence and the divergence movement. The transportation of the convergence or divergence movement is important for the atmospheric boundary layer of the heterogeneous underlying surface and the convection boundary layer. Based on this, the turbulent transportation in the atmospheric boundary layer, the energy budget of the heterogeneous underlying surface and the convection boundary layer, and the boundary layer parameterization of land surface processes over the heterogeneous underlying surface are studied. This research offers clues not only for establishing the atmospheric boundary layer theory about the heterogeneous underlying surface, but also for overcoming the difficulties encountered recently in the application of the atmospheric boundary layer theory.展开更多
Described in this paper is an experiment on atmosphere-surface turbulent exchange and boundary layer turbulence properties conducted in July 1994 over the Kerqin Grassland,Jilin, China.The characteristics of the turbu...Described in this paper is an experiment on atmosphere-surface turbulent exchange and boundary layer turbulence properties conducted in July 1994 over the Kerqin Grassland,Jilin, China.The characteristics of the turbulent spectrum,and the relationships of the standard deviation of the turbulent velocity components and sensible heat flux with the atmospheric stability are studied using data from a sonic anemometer and a fast-response platinum resistance thermometer mounted on a 100 m tower.The results show that in the surface layer over a flat, uniform and open grassland,for a broad stability range(-22.12≤Z_L≤17.98),the velocity spectra obey the-2/3 power law in the inertial subrange,and 1 power law at low frequencies. Under near neutral stratification,σ_u/u_*=1.20,σ_v/u_*=1.23 and σ_w/u_*=1.02.For Z_i/L≤ -0.2,the standard deviations of the turbulent velocity components follow a 1/3 power law.For Z_i/L≤-0.1,the standard deviation of the temperature fluctuations follows a-1/3 power law, and as Z_i/L≤-0.08,it exhibits nonlinear behavior.Sensible heat flux is well correlated to the stability parameter.展开更多
Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temper...Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs （z∧）= φθ（Z/∧） =αθ（-Z/ ∧）-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ（Z/∧）= αs （1 - βs z /∧）-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov （M-O） scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA ＋ δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA ＋ δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing.展开更多
The Monin-Obukhov(MO)similarity functionφm of the atmospheric surface layer(ASL)describing the deviation from the log law of the canonical turbulent boundary layer because of thermal stratification has been tradition...The Monin-Obukhov(MO)similarity functionφm of the atmospheric surface layer(ASL)describing the deviation from the log law of the canonical turbulent boundary layer because of thermal stratification has been traditionally determined empirically.This study presents a unified analytic expression derived from a symmetry-based theory of wall turbulence,called structural ensemble dynamics(SED),which postulates a generalized dilation symmetry principle expressing the effect of the wall on turbulence,leading to an analytic multi-regimes expression for the mixing length.For ASL in unstable and stable conditions(i.e.,UC and SC),a unified two-regime formula of the mixing length is proposed,leading to aφm,similar to the Businger-Dyer(BD)formula;with a simplified model energy balance equation,φm is completely specified with no free parameter.Furthermore,the theory allows the study of the open ASL’s underlying additional physical processes such as bottom-up or top-down flux due to pressure variations Tp.Assuming that Tp is decomposed into shear-like and buoyancy-like components,we propose new explanations for two important features of typical ASL:a significantly smaller Karman constant of 0.36 and a varyingφm for SC mean speed profiles.The theory is validated by the data obtained at Kansas and also at Qingtu Lake Observation Array in Northern China for a variety of heat flux conditions.In conclusion,due to pressure variations,we assert that ASL is intrinsically open and that the current theory offers a new basis for its quantification.展开更多
基金supported by the National High Technology Research and Development Program of China(Grant No.2007AA022201)the National Special Fund for Water(Grant No.2008ZX07103007)+1 种基金the National Basic Research Program of China (Grant Nos.2010CB428503 and 2011CB403406)the National Natural Science Foundation of China(Grant Nos. 40805006 and 41075012)
文摘Turbulence characteristics of an atmospheric surface layer over a coastal mountain area were investigated under different coordinate frames. Performances of three methods of coordinate rotation： double rotation （DR）, triple rotation （TR）, and classic planar-fit rotation （PF） were examined in terms of correction of eddy covariance flux. Using the commonly used DR and TR methods, unreasonable rotation angles are encountered at low wind speeds and cause significant run-to-run errors of some turbulence characteristics. The PF method rotates the coordinate system to an ensemble-averaged plane, and shows large tilt error due to an inaccurate fit plane over variable terrain slopes. In this paper, we propose another coordinate rotation scheme. The observational data were separated into two groups according to wind direction. The PF method was adapted to find an ensemble-averaged streamline plane for each group of hourly runs with wind speed exceeding 1.0 m s-1. Then, the coordinate systems were rotated to their respective best- fit planes for all available hourly observations. We call this the PF10 method. The implications of tilt corrections for the turbulence characteristics are discussed with a focus on integral turbulence characteristics, the spectra of wind-velocity components, and sensible heat and momentum fluxes under various atmospheric stabilities. Our results show that the adapted application of PF provides greatly improved estimates of integral turbulence characteristics in complex terrain and maintains data quality. The comparisons of the sensible heat fluxes for four coordinate rotation methods to fluxes before correction indicate that the PF10 scheme is the best to preserve consistency between fluxes.
基金Supported by The Special Project of Public Welfare Industry(Meteorology)of Science and Technology Ministry(GYHY200806020)The National Natural Science Fund(40975084)The Science Research Fund of Liaoning Meteorological Bureau(2008008)
文摘By using the meteorological data in the pollution boundary layer which was observed in two ground observation sites:coast and land in the river outlet area of Grand Liao River during January-February in 2007,the daily change characteristics of pollute boundary layer in winter in the area were discussed. The results showed that the pollute boundary layer in the river outlet area of Grand Liao River was affected by the sea and land. In the certain weather condition,maybe the sea-land breeze appeared in the low altitude which was below 200 m in the coastal zone. The stability change in the different height in the coastal zone was more stable than in the land zone,and the wind field change in the area was mainly in 300 m low altitude. At night,the temperature inversion often appears in the area,and the thickness of temperature inversion layer is stably during 200-300 m. The thermal internal boundary layer penetrated deeply into the land about 10 km,and the height could reach 800 m. The atmospheric diffusion ability in the coastal area was weaker and stronger in the land area.
基金supported by the National Natural Science Foundation of China under Grant Nos.49835010 and 40233035
文摘Classical turbulent K closure theory of the atmospheric boundary layer assumes that the vertical turbulent transport flux of any macroscopic quantity is equivalent to that quantity's vertical gradient transport flux. But a cross coupling between the thermodynamic processes and the dynamic processes in the atmospheric system is demonstrated based on the Curier-Prigogine principle of cross coupling of linear thermodynamics. The vertical turbulent transportation of energy and substance in the atmospheric boundary layer is related not only to their macroscopic gradient but also to the convergence and the divergence movement. The transportation of the convergence or divergence movement is important for the atmospheric boundary layer of the heterogeneous underlying surface and the convection boundary layer. Based on this, the turbulent transportation in the atmospheric boundary layer, the energy budget of the heterogeneous underlying surface and the convection boundary layer, and the boundary layer parameterization of land surface processes over the heterogeneous underlying surface are studied. This research offers clues not only for establishing the atmospheric boundary layer theory about the heterogeneous underlying surface, but also for overcoming the difficulties encountered recently in the application of the atmospheric boundary layer theory.
基金the State Key Laboratory of Atmosphere Physics and Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences.
文摘Described in this paper is an experiment on atmosphere-surface turbulent exchange and boundary layer turbulence properties conducted in July 1994 over the Kerqin Grassland,Jilin, China.The characteristics of the turbulent spectrum,and the relationships of the standard deviation of the turbulent velocity components and sensible heat flux with the atmospheric stability are studied using data from a sonic anemometer and a fast-response platinum resistance thermometer mounted on a 100 m tower.The results show that in the surface layer over a flat, uniform and open grassland,for a broad stability range(-22.12≤Z_L≤17.98),the velocity spectra obey the-2/3 power law in the inertial subrange,and 1 power law at low frequencies. Under near neutral stratification,σ_u/u_*=1.20,σ_v/u_*=1.23 and σ_w/u_*=1.02.For Z_i/L≤ -0.2,the standard deviations of the turbulent velocity components follow a 1/3 power law.For Z_i/L≤-0.1,the standard deviation of the temperature fluctuations follows a-1/3 power law, and as Z_i/L≤-0.08,it exhibits nonlinear behavior.Sensible heat flux is well correlated to the stability parameter.
基金supported by the National Basic Research Program of China (Grant No.2010CB951701-2)the National Natural Science Foundation of China (Grant Nos. 91025011, 41130961)the Pingliang Station of Lightning and Hail Research, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences
文摘Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs （z∧）= φθ（Z/∧） =αθ（-Z/ ∧）-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ（Z/∧）= αs （1 - βs z /∧）-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov （M-O） scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA ＋ δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA ＋ δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing.
基金supported by the National Natural Science Foundation of China(Grant No.91952201)。
文摘The Monin-Obukhov(MO)similarity functionφm of the atmospheric surface layer(ASL)describing the deviation from the log law of the canonical turbulent boundary layer because of thermal stratification has been traditionally determined empirically.This study presents a unified analytic expression derived from a symmetry-based theory of wall turbulence,called structural ensemble dynamics(SED),which postulates a generalized dilation symmetry principle expressing the effect of the wall on turbulence,leading to an analytic multi-regimes expression for the mixing length.For ASL in unstable and stable conditions(i.e.,UC and SC),a unified two-regime formula of the mixing length is proposed,leading to aφm,similar to the Businger-Dyer(BD)formula;with a simplified model energy balance equation,φm is completely specified with no free parameter.Furthermore,the theory allows the study of the open ASL’s underlying additional physical processes such as bottom-up or top-down flux due to pressure variations Tp.Assuming that Tp is decomposed into shear-like and buoyancy-like components,we propose new explanations for two important features of typical ASL:a significantly smaller Karman constant of 0.36 and a varyingφm for SC mean speed profiles.The theory is validated by the data obtained at Kansas and also at Qingtu Lake Observation Array in Northern China for a variety of heat flux conditions.In conclusion,due to pressure variations,we assert that ASL is intrinsically open and that the current theory offers a new basis for its quantification.
