Monin–Obukhov Similarity Functions for the Structure Parameters of Temperature and Humidity

2011 ◽  
Vol 145 (1) ◽  
pp. 45-67 ◽  
Author(s):  
Dan Li ◽  
Elie Bou-Zeid ◽  
Henk A. R. De Bruin
Keyword(s):  
Structure Parameters ◽  
Similarity Functions ◽  
Temperature And Humidity

scholarly journals Monin–Obukhov Similarity Functions for the Structure Parameters of Temperature and Humidity in the Unstable Surface Layer: Results from High-Resolution Large-Eddy Simulations

2014 ◽  
Vol 71 (2) ◽  
pp. 716-733 ◽  
Author(s):  
Björn Maronga
Keyword(s):  
Surface Layer ◽  
Free Convection ◽  
Measurement Data ◽  
Surface Fluxes ◽  
Large Eddy Simulations ◽  
Structure Parameters ◽  
Similarity Functions ◽  
Dry Air ◽  
Large Eddy ◽  
Temperature And Humidity

Abstract Large-eddy simulations (LESs) of free-convective to near-neutral boundary layers are used to investigate the surface-layer turbulence. The article focuses on the Monin–Obukhov similarity theory (MOST) relationships that relate the structure parameters of temperature and humidity to the surface fluxes of sensible and latent heat, respectively. Moreover, the applicability of local free convection (LFC) similarity scaling is studied. The LES data suggest that the MOST function for is universal. It is shown to be within the range of the functions proposed from measurement data. It is found that follows MOST if entrainment of dry air from the free atmosphere is sufficiently small. In this case the similarity functions for and are identical. If entrainment is significant, dissimilarity between the transport of sensible heat and moisture is observed and no longer follows MOST. In the free-convection limit the LFC similarity functions should collapse to universal constants. The LES data suggest values around 2.7, which is in agreement with the value proposed in the literature. As for MOST, the LFC similarity constant for becomes nonuniversal if entrainment of dry air is significant. It is shown that LFC scaling is applicable even if shear production of turbulence is moderately high.

scholarly journals Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

2014 ◽  
Vol 7 (11) ◽  
pp. 11169-11220 ◽  
Author(s):  
H. C. Ward ◽  
J. G. Evans ◽  
C. S. B. Grimmond ◽  
J. Bradford
Keyword(s):  
Eddy Covariance ◽  
Similarity Theory ◽  
Correlation Method ◽  
Source Area ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Structure Parameters ◽  
Millimetre Wave ◽  
Vegetation Fraction ◽  
Temperature And Humidity

Abstract. Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A unique millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations and the so-called "bichromatic-correlation" method is also used to retrieve the path-averaged temperature-humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the techniques under different conditions is discussed. Similar behaviour is seen between the two datasets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1) compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the copanion paper.

Structure parameters for temperature and humidity from simultaneous eddy-covariance and scintillometer measurements

2005 ◽  
Vol 14 (5) ◽  
pp. 641-649 ◽  
Author(s):  
Frank Beyrich ◽  
Rostislav D. Kouznetsov ◽  
Jens-Peter Leps ◽  
Andreas Lüdi ◽  
Wouter M.L. Meijninger ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Structure Parameters ◽  
Temperature And Humidity

scholarly journals Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

2015 ◽  
Vol 8 (3) ◽  
pp. 1385-1405 ◽  
Author(s):  
H. C. Ward ◽  
J. G. Evans ◽  
C. S. B. Grimmond ◽  
J. Bradford
Keyword(s):  
Eddy Covariance ◽  
Similarity Theory ◽  
Measurement Techniques ◽  
Source Area ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Structure Parameters ◽  
Millimetre Wave ◽  
Vegetation Fraction ◽  
Temperature And Humidity

Abstract. Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations, and the correlation between wavelengths is also used to retrieve the path-averaged temperature–humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the measurement techniques under different conditions is discussed. Similar behaviour is seen between the two data sets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1) compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the companion paper.

Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

1993 ◽  
Vol 51 ◽  
pp. 876-877
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Microstructural Characterization ◽  
Building Blocks ◽  
Quantitative Information ◽  
Physical Models ◽  
Specimen Preparation ◽  
Time Resolved ◽  
Temperature Changes ◽  
Temperature And Humidity ◽  
Microstructured Fluids ◽  
Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

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