Estimation of the sensible heat flux and the temperature structure parameter by sodar and sonic anemometer: an intercomparison

1994 ◽  
Vol 15 (2) ◽  
pp. 507-516 ◽  
Author(s):  
S. VOGT ◽  
P. THOMAS
Keyword(s):  
Heat Flux ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Temperature Structure ◽  
Sensible Heat ◽  
Structure Parameter ◽  
Temperature Structure Parameter

scholarly journals On the Temperature Structure Parameter and Sensible Heat Flux over Helsinki from Sonic Anemometry and Scintillometry

2013 ◽  
Vol 30 (8) ◽  
pp. 1604-1615 ◽  
Author(s):  
C. R. Wood ◽  
R. D. Kouznetsov ◽  
R. Gierens ◽  
A. Nordbo ◽  
L. Järvi ◽  
...  
Keyword(s):  
Heat Flux ◽  
Measurement Techniques ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Temperature Structure ◽  
Sensible Heat ◽  
Structure Parameter ◽  
Large Variability ◽  
Temperature Structure Parameter ◽  
Depth Analysis

Abstract Two commercial large-aperture scintillometers, Scintec BLS900, were tested on pathlengths of 1840 and 4200 m at about 45–65 m above ground in Helsinki, Finland. From July 2011 through June 2012, large variability in diurnal and annual cycles of both the temperature structure parameter and sensible heat flux were observed. Scintillometer data were compared with data from two eddy-covariance stations. A robust method was developed for the calculation of from raw sonic-anemometer data. In contrast to many earlier studies that solely present the values of , the main focus here is on comparisons of itself. This has advantages, because optical-wavelength scintillometers measure with few assumptions, while the determination of implies the applicability of the Monin–Obukhov similarity theory, which has several inherent limitations. The histograms of compare well between sonic and scintillometer. In-depth analysis is focused on one of the scintillometer paths: both and comparisons gave similar and surprisingly high correlation coefficients (0.85 for and 0.84–0.95 for in unstable conditions), given the differences between the two measurement techniques, substantial sensor separation, and different source areas.

scholarly journals A Feasibility Study for Determining the Sensible Heat Flux to and from Small Green Roofs

2021 ◽  
Author(s):  
Niels Wollschläger ◽  
Uwe Schlink ◽  
Armin Raabe
Keyword(s):  
Heat Flux ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Three Dimensional ◽  
Source Area ◽  
Surface Characteristics ◽  
Green Roofs ◽  
Heat Fluxes ◽  
Horizontal Wind ◽  
Sensible Heat

AbstractEddy covariance is an established technique for registering sensible heat fluxes. However, this method is less adequate for smaller surfaces that cannot match the associated footprint. As an alternative technique, a recently constructed acoustic anemometer (Ly-ATOM) is tested, which operates horizontally at an extension of circa 1 m and a data-acquisition frequency of 1 Hz. The Ly-ATOM device reproduces both the acoustic virtual temperature and the horizontal wind components registered by a three-dimensional sonic anemometer. As this Ly-ATOM device can be applied much closer to the ground compared with a sonic anemometer, the size of the related source area is significantly reduced (by a factor of 25). Two methods are used to retrieve the sensible heat flux from variance characteristics of temperature and the horizontal wind components recorded by the Ly-ATOM device: combining the flux-variance-similarity and alternative-flux-variance methods for use in unstable and stable stratification, respectively, yields good results for the sonic measurements. Therefore, these methods can be applied to the Ly-ATOM device as well. In investigating the sensitivity to detect modified surface characteristics, specifically increased evapotranspiration and decreased surface albedo, the Ly-ATOM device proves to be superior to the sonic anemometer which is more vertically removed from the surface of interest.

scholarly journals Using sonic anemometer temperature to measure sensible heat flux in strong winds

2012 ◽  
Vol 5 (1) ◽  
pp. 447-469 ◽  
Author(s):  
S. P. Burns ◽  
T. W. Horst ◽  
P. D. Blanken ◽  
R. K. Monson
Keyword(s):  
Heat Flux ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Horizontal Wind ◽  
Subalpine Forest ◽  
Sensible Heat ◽  
Scientific Model ◽  
Horizontal Wind Speed ◽  
Sonic Anemometers

Abstract. The sensible heat flux (H) is a significant component of the surface energy balance (SEB). Sonic anemometers simultaneously measure the turbulent fluctuations of vertical wind (w') and sonic temperature (Ts'), and are commonly used to measure H. Our study examines 30-min heat fluxes measured with a Campbell Scientific model CSAT3 sonic anemometer above a subalpine forest. We compare H calculated with Ts to H calculated with a co-located thermocouple and find that for horizontal wind speed (U) less than 8 m s−1 the agreement is ≈±30 W m−2. However, for U >≈ 8 m s−1, the CSAT3 H becomes larger than H calculated with the thermocouple, reaching a maximum difference of ≈250 W m−2 at U ≈ 18 m s−1. H calculated with the thermocouple results in a SEB that is relatively independent of U at high wind speeds. In contrast, the SEB calculated with H from the CSAT3 varies considerably with U, particularly at night. Cospectral analysis of w'Ts' suggest that spurious correlation is a problem during high winds which leads to a positive (additive) increase in H calculated with the CSAT3. At night, when H is typically negative, this CSAT3 error results in a measured H that falsely approaches zero or even becomes positive. Within a broader context, the usefulness of side-by-side instrument comparisons are discussed.

scholarly journals Using sonic anemometer temperature to measure sensible heat flux in strong winds

2012 ◽  
Vol 5 (9) ◽  
pp. 2095-2111 ◽  
Author(s):  
S. P. Burns ◽  
T. W. Horst ◽  
L. Jacobsen ◽  
P. D. Blanken ◽  
R. K. Monson
Keyword(s):  
Heat Flux ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Horizontal Wind ◽  
Subalpine Forest ◽  
Sensible Heat ◽  
Horizontal Wind Speed ◽  
Sonic Anemometers ◽  
Significant Underestimation

Abstract. Sonic anemometers simultaneously measure the turbulent fluctuations of vertical wind (w') and sonic temperature (Ts'), and are commonly used to measure sensible heat flux (H). Our study examines 30-min heat fluxes measured with a Campbell Scientific CSAT3 sonic anemometer above a subalpine forest. We compared H calculated with Ts to H calculated with a co-located thermocouple and found that, for horizontal wind speed (U) less than 8 m s−1, the agreement was around ±30 W m−2. However, for U ≈ 8 m s−1, the CSAT H had a generally positive deviation from H calculated with the thermocouple, reaching a maximum difference of ≈250 W m−2 at U ≈ 18 m s−1. With version 4 of the CSAT firmware, we found significant underestimation of the speed of sound and thus Ts in high winds (due to a delayed detection of the sonic pulse), which resulted in the large CSAT heat flux errors. Although this Ts error is qualitatively similar to the well-known fundamental correction for the crosswind component, it is quantitatively different and directly related to the firmware estimation of the pulse arrival time. For a CSAT running version 3 of the firmware, there does not appear to be a significant underestimation of Ts; however, a Ts error similar to that of version 4 may occur if the CSAT is sufficiently out of calibration. An empirical correction to the CSAT heat flux that is consistent with our conceptual understanding of the Ts error is presented. Within a broader context, the surface energy balance is used to evaluate the heat flux measurements, and the usefulness of side-by-side instrument comparisons is discussed.

scholarly journals A New Procedure Based on Surface Renewal Analysis to Estimate Sensible Heat Flux: A Case Study over Grapevines

2010 ◽  
Vol 11 (2) ◽  
pp. 496-508 ◽  
Author(s):  
F. Castellví ◽  
R. L. Snyder
Keyword(s):  
Heat Flux ◽  
Low Cost ◽  
Sonic Anemometer ◽  
Sensible Heat Flux ◽  
Energy Balance Equation ◽  
Sensible Heat ◽  
Surface Renewal ◽  
The Stability ◽  
Crop Coefficients ◽  
A Site

Abstract Grapevines are grown on a range of soils and in different climates. Depending on the desired final product and method of harvesting, the trellis system, and hence vineyard architecture, varies dramatically. Consequently, the crop coefficients used to estimate vineyard evapotranspiration from reference evapotranspiration are less universal than for other crops. Evapotranspiration measurements are often limited because of a lack of fetch and unavailability of vine parameters required as input. In this paper, a new procedure based on surface renewal (SR) analysis was derived to estimate sensible heat flux over the grapevines. A two-dimensional sonic anemometer operating close to the canopy can provide the inputs required to estimate the sensible heat flux and the work of expansion of the air parcels under constant pressure. Regardless of the stability conditions, the SR estimates were comparable to those determined using the eddy covariance (EC) method providing a root-mean-square error of 14 W m−2 for all data. Thus, the procedure is low cost and makes SR a simpler method than EC to estimate latent heat flux as the residual of the energy balance equation in moderately tall and heterogeneous crops. The experiment was carried out at a site influenced by regional advection of sensible heat flux.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

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