scholarly journals Doppler Sodar Observations of the Diurnal Variations of the Atmospheric Boundary Layer over Gadanki, a Tropical Rural Station

2017 ◽  
Vol Volume-2 (Issue-1) ◽  
pp. 517-522
Author(s):  
D. Sharmila ◽  
Prof. M. P. Rao ◽  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Diurnal Variations ◽  
Rural Station ◽  
Doppler Sodar

scholarly journals Solutions to the 3D Transport Equation and 1D Diffusion Equation for Passive Tracers in the Atmospheric Boundary Layer and Their Applications

2019 ◽  
Vol 2019 (1) ◽  
pp. 21-47 ◽  
Author(s):  
Shuzhan Ren
Keyword(s):  
Boundary Layer ◽  
Diffusion Equation ◽  
Atmospheric Boundary Layer ◽  
Transport Equation ◽  
Analytical Solutions ◽  
Inverse Modeling ◽  
Surface Flux ◽  
Diurnal Variations ◽  
Surface Fluxes ◽  
Passive Tracers

Abstract A solution to the 3D transport equation for passive tracers in the atmospheric boundary layer (ABL), formulated in terms of Green’s function (GF), is derived to show the connection between the concentration and surface fluxes of passive tracers through GF. Analytical solutions to the 1D vertical diffusion equation are derived to reveal the nonlinear dependence of the concentration and flux on the diffusivity, time, and height, and are employed to examine the impact of the diffusivity on the diurnal variations of CO2 in the ABL. The properties of transport operator H and their implications in inverse modeling are discussed. It is found that H has a significant contribution to the rectifier effect in the diurnal variations of CO2. Since H is the integral of GF in time, the narrow distribution of GF in time justifies the reduction of the size of H in inverse modeling. The exponential decay of GF with height suggests that the estimated surface fluxes in inverse modeling are more sensitive to the observations in the lower ABL. The solutions and first mean value theorem are employed to discuss the uncertainties associated with the concentration–mean surface flux equation used to link the concentrations and mean surface flux. Both analytical and numerical results show that the equation can introduce big errors, particularly when surface flux is sign indefinite. Numerical results show that the conclusions about the evolution properties of passive tracers based on the analytical solutions also hold in the cases with a more complicated diffusion coefficient and time-varying ABL height.

Evaluating the response of the diurnal range of surface and air temperature to evaporative conditions across vegetation types in ERA5 and FLUXNET data

2021 ◽  
Author(s):  
Annu Panwar ◽  
Axel Kleidon
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Air Temperature ◽  
Extreme Events ◽  
Heat Storage ◽  
Vegetation Type ◽  
Diurnal Variations ◽  
Vegetation Types ◽  
Evaporative Fraction ◽  
Simple Boundary

<p>The diurnal variations of surface and air temperature are related but their different responses to evaporative conditions can inform us about land-atmosphere interactions, extreme events, and their response to global change. Here, we evaluate the sensitivity of the diurnal ranges of surface (DT<sub>s</sub>R) and air (DT<sub>a</sub>R) temperature to evaporative fraction, across short vegetation, savanna, and forests at 106 Fluxnet observational sites and in the ERA5 global reanalysis. We show that the sensitivity of DT<sub>s</sub>R to evaporative fraction depends on vegetation type, whereas for DT<sub>a</sub>R it does not. Using FLUXNET data we found that on days with low evaporative fraction, DT<sub>s</sub>R is enhanced by up to 20 °C (30 °C in ERA5) in short vegetation, whereas only by 8 °C (10 °C in ERA5) in forests. Particularly, in short vegetation, ERA5 shows stronger responses, which is attributable to a negative bias on days with the high evaporative fraction. ERA5 also tends to have lower shortwave and longwave radiation input when compared to FLUXNET data. Contrary to DT<sub>s</sub>R, DT<sub>a</sub>R responds rather similarly to evaporative fraction irrespective of vegetation type (8 °C in FLUXNET, 10 °C in ERA5). To explain this, we show that the DT<sub>a</sub>R response to the evaporative fraction is compensated for differences in atmospheric boundary layer height by up to 2000 m, which is similar across vegetation types. We demonstrate this with a simple boundary layer heat storage calculation, indicating that DT<sub>a</sub>R is primarily shaped by changes in boundary layer heat storage whereas DT<sub>s</sub>R mainly responds to solar radiation, evaporation, and vegetation.  Our study reveals some systematic biases in ERA5 that need to be considered when using its temperature products for understanding land-atmosphere interactions or extreme events. To conclude, this study demonstrates the importance of vegetation and the dynamics of the atmospheric boundary layer in regulating diurnal variations in surface and air temperature under different evaporative conditions.</p>

A study of the spatial structure of the atmospheric boundary layer with a Doppler-Sodar network

2009 ◽  
Vol 45 (5) ◽  
pp. 541-548 ◽  
Author(s):  
I. G. Granberg ◽  
V. F. Kramar ◽  
R. D. Kuznetsov ◽  
O. G. Chkhetiani ◽  
M. A. Kallistratova ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Spatial Structure ◽  
Atmospheric Boundary Layer ◽  
Doppler Sodar

scholarly journals Turbulence, Low-Level Jets, and Waves in the Tyrrhenian Coastal Zone as Shown by Sodar

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 28 ◽  
Author(s):  
Igor Petenko ◽  
Giampietro Casasanta ◽  
Simone Bucci ◽  
Margarita Kallistratova ◽  
Roberto Sozzi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Vertical Wind ◽  
Land Breeze ◽  
Tyrrhenian Sea ◽  
Turbulent Layer ◽  
Low Level ◽  
Doppler Sodar ◽  
Low Level Jets

The characteristics of the vertical and temporal structure of the coastal atmospheric boundary layer are variable for different sites and are often not well known. Continuous monitoring of the atmospheric boundary layer was carried out close to the Tyrrhenian Sea, near Tarquinia (Italy), in 2015–2017. A ground-based remote sensing instrument (triaxial Doppler sodar) and in situ sensors (meteorological station, ultrasonic anemometer/thermometer, and net radiometer) were used to measure vertical wind velocity profiles, the thermal structure of the atmosphere, the height of the turbulent layer, turbulent heat and momentum fluxes in the surface layer, atmospheric radiation, and precipitation. Diurnal alternation of the atmospheric stability types governed by the solar cycle coupled with local sea/land breeze circulation processes is found to be variable and is classified into several main regimes. Low-level jets (LLJ) at heights of 100–300 m above the surface with maximum wind speed in the range of 5–18 m s−1 occur in land breezes, both during the night and early in the morning. Empirical relationships between the LLJ core wind speed characteristics and those near the surface are obtained. Two separated turbulent sub-layers, both below and above the LLJ core, are often observed, with the upper layer extending up to 400–600 m. Kelvin–Helmholtz billows associated with internal gravity–shear waves occurring in these layers present opposite slopes, in correspondence with the sign of vertical wind speed gradients. Our observational results provide a basis for the further development of theoretical and modelling approaches, taking into account the wave processes occurring in the atmospheric boundary layer at the land–sea interface.

Diurnal Variations of the Electric Field in the Atmospheric Boundary Layer

2021 ◽  
Vol 57 (4) ◽  
pp. 397-405
Author(s):  
A. Kh. Adzhiev ◽  
A. G. Klovo ◽  
T. V. Kudrinskaya ◽  
G. V. Kupovykh ◽  
D. V. Timoshenko
Keyword(s):  
Boundary Layer ◽  
Electric Field ◽  
Atmospheric Boundary Layer ◽  
Diurnal Variations
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