Effects of different eddy covariance correction schemes on energy balance closure and comparisons with the modified Bowen ratio system

Wolf, Adam; Saliendra, Nick; Akshalov, Kanat; Johnson, Douglas A.; Laca, Emilio A.

doi:10.1016/j.agrformet.2008.01.005

Cited by 75 publications

(62 citation statements)

References 29 publications

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“…These kinds of corrections are still extremely problematic (Massman and Lee, 2002). Wolf et al (2008) found that path-length averaging effect was A. Lindroth et al: Heat storage in forest biomass important for the open-path gas analyzer at a low height over short vegetation.…”

Section: Introductionmentioning

confidence: 99%

Heat storage in forest biomass improves energy balance closure

2010

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Abstract.Temperature measurements in trunks and branches in a mature ca. 100 years-old mixed pine and spruce forest in central Sweden were used to estimate the heat storage in the tree biomass. The estimated heat flux in the sample trees and data on biomass distributions were used to scale up to stand level biomass heat fluxes. The rate of change of sensible and latent heat storage in the air layer below the level of the flux measurements was estimated from air temperature and humidity profile measurements and soil heat flux was estimated from heat flux plates and soil temperature measurements. The fluxes of sensible and latent heat from the forest were measured with an eddy covariance system in a tower. The analysis was made for a two-month period in summer of 1995. The tree biomass heat flux was the largest of the estimated storage components and varied between 40 and −35 W m −2 on summer days with nice weather. Averaged over two months the diurnal maximum of total heat storage was 45 W m −2 and the minimum was −35 W m −2 . The soil heat flux and the sensible heat storage in air were out of phase with the biomass flux and they reached maximum values that were about 75% of the maximum of the tree biomass heat storage. The energy balance closure improved significantly when the total heat storage was added to the turbulent fluxes. The slope of a regression line with sum of fluxes and storage as independent and net radiation as dependent variable, increased from 0.86 to 0.95 for half-hourly data and the scatter was also reduced. The most significant finding was, however, that during nights with strongly stable conditions when the sensible heat flux dropped to nearly zero, the total storage matched the net radiation very well. Another interesting result was that the mean energy imbalance started to increase when the Richardson number became more negative than ca. −0.1. In fact, the largest energy deficit occurred at Correspondence to: A. Lindroth (anders.lindroth@nateko.lu.se) maximum instability. Our conclusion is that eddy covariance measurements can function well during stable conditions but that the functioning under strong instabilities might be a so far unforeseen problem.

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Section: Introductionmentioning

confidence: 99%

Heat storage in forest biomass improves energy balance closure

2010

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“…Anyhow, the reradiating heat energy from ceiling of flattop-concrete house was supposed to be the main factor involving with less changing room temperature due to high heat conductivity. Since the decrease of sensible heat flux on flattop-concrete roof and surroundings was absorbed to change into latent heat flux by green plants through the evapotranspiration processes before heat energy translocation to the ceiling of the room as pointed out by Gates (1965;1980), Geiger & Todhunter (2003), Abou-Korin (2014), Ashktorab et al (1989), Botkin & Keller (2011), Bowen (1926, Chun & Guldmann (2014), Chunkao (1971;1979;2004), Coseo & Larsen (2014), Maimaitiyiming et al (2014), Mangone & van der Linden (2014), Heilman & Brittin (1989), Holland et al (2013), Honjo & Takakura (1990, Lee et al (2004), Verma et al (1978), Wolf et al (2008).…”

Section: Lag Time Temperaturementioning

confidence: 99%

“…The flattop-concrete roof temperature would be rather higher than the another 4-point ground temperature because of roof concrete re-radiation as accumulated from direct solar radiation (Sellers, 1965;Wolf et al, 2008;Zhang et al, 2013;Lee et al, 2004;Oke et al, 1991). Anyhow, the rainfall and/shower were still played role in decreasing outside room temperature while inside room temperature not only higher temperature but also gradually lowering due to low heat translocations through lightweight-concrete along with low thermal conductivity in taking longer lag time (Arneth & Stichlmair, 2001;Sellers, 1965;Hartman, 1994;Heilman & Brittin, 1989;Ashktorab et al, 1989;Chunkao, 1979;Gates, 1965;1980).…”

Section: Lag Time Temperaturementioning

confidence: 99%

“…Among aforesaid environmental problems, hot climate plays vital role in humid populated cities along with dense households, particularly the cities as located in the tropical zone that causing more hotter conditions that might be urban heat island (Takebayashi et al, 2014;Verma et al, 1978;Wolf et al, 2008). In general, the urban heat island is the area (municipal, urban, suburban and dense-populated community areas) to elevate temperature.…”

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confidence: 99%

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Lag Time of Heat Conduction in Conditions of Growing Greenery Cover on Flattop-Concrete Roof of Single-Room House with Lightweight-Concrete Walls as Constructed on Narrow Space in Bangkok

Suwansumrit¹,

Chunkao²,

Bualert³

et al. 2015

MAS

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Growing greenery cover on flattop-concrete roof of single-room house with lightweight-concrete walls for lagging heat conduction was experimented during 10 August-30 November 2014 at Kasetsart University on narrow space between the College of Environment and car park buildings which emphasized on minimum room size of 2.5 m width, 2.5 m length, and 2.5 m height as declared by Building Control Act 1990. The methods of study were conducted by installing air thermometers at distance from the house and one meter above ground in northerly, southerly, easterly, westerly and flattop-concrete roof by alternating closing and opening the door and window. The research results found the maximum room temperature ranging 34.5-35.5 o C and minimum 26.5-27.7 o C for closing door and closing window, then decreasing almost being equal from degree of opening door and window, and clearly changing in conditions of long duration, high intensity, and often frequency of rainfall. Using Pudsaon or Cape Jasmine (Gardenia jasminoides J.Ellis) as grown in experimental pots containing coconut flake due to its characteristics of more consuming phreatophyte with high rate of using water for evapotranspiration process that can absorb surrounding heat through converting process to become latent heat flux. In consequence, room temperature was lowered down to 24.5 o C and following by decreasing lag time from 2 hours to 0.5 hours, and also different lag time from 1-2 hours to 0.5-1.5 hours which were indicated better comfortable living. Closing both door and window or either one could not be conditioned for everyday lifestyle of people in dense and populated Bangkok city. In addition, construction of single-room house with flattop-concrete roof and lightweight-concrete walls were surely eligible to protect heat transferring from hot air outside into room rather than from room to outside, except opening both door and window at the same time

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“…The lack of the energy balance closure in EC systems can be related to malfunctions of the sensors during rainfall conditions; instrumental maintenance; neglected energy sinks; heat storage in the top soil; loss of low and/or high frequency contributions to the turbulent heat fluxes; advection of scalars; different correction algorithms used to process the data; flux divergence in the boundary layer; non-uniform footprint; non-representative sensing of R n and G; proper average times; and when neglecting of the energy stored in the tree canopies for accounting for the available energy partitioning Baldocchi et al 2001;Scott et al 2003a, b;Papale et al 2006;Wolf et al 2008;Castellvi et al 2008). Yet, after applying algorithms for general corrections to kE EC and H EC , energy balance closure errors still remain in the other energy balance components (Allen 2008).…”

Section: Introductionmentioning

confidence: 99%

Five methods to interpret field measurements of energy fluxes over a micro-sprinkler-irrigated mango orchard

Teixeira

Bastiaanssen

2010

Irrig Sci

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Energy balance measurements were carried out in a mango orchard during two growing seasons in the semi-arid region of Brazil. The actual evapotranspiration (ET) was acquired by eddy correlation (EC) and Bowen ratio energy balance (BR) techniques. The daily energy balance closure in the EC measurements showed an average gap of 12%, with a root mean square error (RMSE) of. Three different correction procedures were tested for closing the energy balance from the EC system: (1) the surface energy balance residual method (RES), (2) the Bowen ratio determined from the EC fluxes, the combination approach (EC_BR), and (3) a new regression energy balance closure technique (REG). All closing energy balance methods presented good correlation with the direct EC measurements, but the trends were not similar. The latent heat fluxes estimated by the BR method-kE BR -were higher than those from the direct EC measurements-kE EC . When using the RES method, the half-hour kE EC measurements represented around 88% of the kE RES values, as the uncertainties of net radiation-R n -and soil heat fluxes-G-are propagated into the RES method. The latent heat flux derived from the combination approach-kE EC_BR -also brings these uncertainties, being the agreements comparable with those for RES method. It was therefore concluded that a single correction method for EC measurements considering only the latent and sensible heat fluxes does not exist. A new way to solve the lack of energy balance closure from EC techniques was tested by means of a curve fitting, the REG method. Considering the REG corrections applied to the energy balance components involving all periods of the day and the average conditions of the two growing seasons, half-hour values of kE EC were overmeasured by 18%, H EC was undermeasured by 17%, and G values required a correction of 466%. The REG method appeared promising because it considers different weights for all energy balance components in the optimization process. Taking the REG results for the drier second growing season as a reference, it was concluded that seasonal ET values by the other methods in mango orchard ranged from 7 to 28% higher, showing that turbulent flux measurements lack accuracy for executing on-farm watersaving programmes and calibrating transient soil water flow models.

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Effects of different eddy covariance correction schemes on energy balance closure and comparisons with the modified Bowen ratio system

Cited by 75 publications

References 29 publications

Heat storage in forest biomass improves energy balance closure

Heat storage in forest biomass improves energy balance closure

Lag Time of Heat Conduction in Conditions of Growing Greenery Cover on Flattop-Concrete Roof of Single-Room House with Lightweight-Concrete Walls as Constructed on Narrow Space in Bangkok

Five methods to interpret field measurements of energy fluxes over a micro-sprinkler-irrigated mango orchard

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