scholarly journals Review for “Drivers of the variability of the isotopic composition of water vapor in the surface boundary layer” by Braden-Behrens et al. (bg-2020-398).

2020 ◽  
Author(s):  
Anonymous
2020 ◽  
Author(s):  
Jelka Braden-Behrens ◽  
Lukas Siebicke ◽  
Alexander Knohl

Abstract. Measurements of the isotopic composition of water vapor, δv, as well as measurements of the isotopic composition of evaporation and transpiration provide valuable insights in the hydrological cycle. Here we present measurements of δv in the surface boundary layer (SBL) in combination with eddy covariance (EC) measurements of the isotopic composition of evapotranspiration δET for both δD as well as δ18O over a full growing season above a managed beech forest in central Germany. Based on direct measurements of isoforcing IF and the height h of the planetary boundary layer (PBL), we provide an estimate of isoforcing-related changes in δv, revealing the influence of local evapotranspiration (ET) on δv. At seasonal time scales we find no evidence for a dominant control of δv by local ET. Rayleigh distillation could at most explain 35 % of the observed variability and we did not find indications for the influence of entrainment at seasonal time scales. Instead, we obtain a strong significant correlation (R2 ≈ 0.52; p 


Author(s):  
Yagya Dutta Dwivedi ◽  
Vasishta Bhargava Nukala ◽  
Satya Prasad Maddula ◽  
Kiran Nair

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.


2012 ◽  
Vol 39 (18) ◽  
Author(s):  
Stephen E. Belcher ◽  
Alan L. M. Grant ◽  
Kirsty E. Hanley ◽  
Baylor Fox-Kemper ◽  
Luke Van Roekel ◽  
...  

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