Variance methods to estimate regional heat fluxes with aircraft measurements in the convective boundary layer

Kotani, Akio; Sugita, Michiaki

doi:10.1016/j.jhydrol.2006.07.029

Cited by 6 publications

(12 citation statements)

References 49 publications

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“…The second group traveled to all relevant RAISE sites during or shortly after each IOP to obtain data and samples such as the leaf area index (LAI), biomass, soil and spectral reflectance at all sites and fluxes at the AWS sites where fluxes were not measured constantly (Table 6). The third group used an aircraft in order to obtain variables in and above the atmospheric boundary layer (Kotani and Sugita, 2006), to make remote sensing of the surface spectral reflectance (Matsushima, 2006), and to capture water vapor samples for the isotopic analysis (Yamanaka et al, 2006). The flight passes and dates are listed in Table 7 and Fig.11.…”

Section: Intensive Observationsmentioning

confidence: 99%

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Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia

Tsujimura

Sasaki

Yamanaka

et al. 2007

Journal of Hydrology

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Intensive observations, analysis and modeling within the framework of the Rangelands Atmosphere-HydrosphereBiosphere Interaction Study Experiment in Northeastern Asia (RAISE) project, have allowed investigations into the hydrologic cycle in the ecotone of forest-steppe, and its relation to atmosphere and ecosystem in the eastern part of Mongolia. In this region, changes in the climate have been reported and a market oriented economy was introduced recently, but their impact on the natural environment is still not well understood. In this RAISE special issue, the outcome is presented of the studies carried out by six groups within RAISE, namely, (1) Landatmosphere interaction analysis, (2) Ecosystem analysis and modeling, (3) Hydrologic cycle analysis, (4) Climatic modeling, (5) Hydrologic modeling, and (6) Integration. The results are organized in five relevant categories comprising (i) hydrologic cycle including precipitation, groundwater, and surface water, (ii) hydrologic cycle and ecosystem, (iii) surface-atmosphere interaction, (iv) effect of grazing activities on soils, plant ecosystem and surface fluxes, and (iv) future prediction. Comparison with studies on rangelands in other parts of the world, and some future directions of studies still needed in this region are also summarized.

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Section: Intensive Observationsmentioning

confidence: 99%

“…Kotani and Sugita (2006) indicates that there is a considerable horizontal variation, for example, in the ragne of 0.5-4.0/mm/day on a sunny summer day even though the general class of vegetation is the same grassland.…”

Section: Atmosphere-surface Interactionsmentioning

confidence: 99%

Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia

Tsujimura

Sasaki

Yamanaka

et al. 2007

Journal of Hydrology

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“…On the other hand, the variance (VA) method is an applicable alternative method for estimating surface fluxes from associated variance measurements (Asanuma and Brutsaert 1999;Kotani and Sugita 2007). The VA method is based on flux-variance relationships, derived using Monin−Obukhov similarity theory.…”

Section: Introductionmentioning

confidence: 99%

Turbulent Flux Observations at the Tip of a Narrow Cape on Miyako Island in Japan's Southwestern Islands

Tanaka

Hiyama

Nakamura

2008

Journal of the Meteorological Society of Japan

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Air-sea fluxes were observed to elucidate the lower boundary conditions in the development of an atmospheric boundary layer over sea from 14 to 27 August 2002. Fluxes were observed at the tip of a narrow cape on Miyako Island, in Japan's Southwestern Islands. Flux measurements and turbulence properties were clearly divided by fetch condition or wind direction. Analysis of the footprint area and homogeneity indicated that air-sea fluxes over an upwind sea surface were observed in cases of approximately 30% for all observation periods. The bulk transfer (BT), eddy covariance (EC), and variance (VA) methods were used to evaluate air-sea fluxes. The general features of the estimated fluxes were similar. Averaged sensible heat flux of approximately 6 W m −2 was obtained by all three methods, and the latent heat fluxes were 92, 60, and 71 W m −2 by the BT, EC, and VA methods, respectively. Daily mean net radiation input R NET was 223 W m −2 . The sea surface was a large energy sink during the observation period.

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“…Therefore, it is still possible that some of these additional parameters play a role in the shape of the C function. Recently, Kotani and Sugita [2007] explored this idea in the formulation of the mixed layer variance similarity. Although in the past there have not been many studies on this subject, the mixed layer temperature variance σ θ scaled with the convective temperature scale T * , namely, ϕ θ = σ θ / T * has been treated as a function of h i and entrainment fluxes [e.g., Sugita and Kawakubo , 2003].…”

Section: Resultsmentioning

confidence: 99%

“…To avoid possible spurious values due to small oscillations in the radiosonde profiles, the validity of the selected height was confirmed visually on a θ versus z plot. For the RAISE data set, use was made of h i values estimated by Kotani and Sugita [2007] by applying the method of Liu and Ohtaki [1997] in which the peak frequency of the spectra of the horizontal wind speed data obtained at the surface flux station was analyzed to estimate h i .…”

Section: Methodsmentioning

confidence: 99%

How universal is the C function in the bulk atmospheric boundary layer similarity approach for estimating surface sensible heat flux?

Sugita

Kato

Kotani

et al. 2009

Water Resources Research

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[1] The C function which appears in the formulation for the bulk atmospheric boundary layer similarity (BAS) approach estimating sensible heat flux (H) at the surface under unstable stability conditions was examined to investigate its universality and whether or not it is a function of atmospheric stability alone, using data sets obtained from five largescale experiments that took place in diverse geographical locations with different surface covers and climate conditions (ranging from the tropics to the boreal zone). Coefficients in several forms of the C function, first assumed as a function of the stability alone, were calibrated against these data sets to maximize the agreement between H values derived from the BAS and those reference values independently determined. The agreement of H values for this calibration, for all data sets except one, was excellent, with a root-mean-square error on the order of 20 W m À2 under the condition that the exact values of surface scalar roughness and atmospheric stability were known. The findings indicate that the C function is a function of stability only and is universal within this accuracy level. Inclusion of another possible parameter, the ratio of the rotational height scale and the actual depth of the mixed layer, did not improve the results. A selection of different scaling for surface layer height did not produce better results, either. Practical limitations of the BAS approach were also investigated by considering one site that did not yield satisfactory results. Using an error propagation analysis, it was determined that this finding was mainly caused by weak surface heating in this area under near neutral conditions and that the difference between the potential temperature at the surface and that in the mixed layer was too small to be used beyond the measurement error limit in the BAS approach. The need for a method to estimate surface scalar roughness was also identified as the largest remaining problem in the BAS approach used for actual flux estimations.Citation: Sugita, M., H. Kato, A. Kotani, and M. Toda (2009), How universal is the C function in the bulk atmospheric boundary layer similarity approach for estimating surface sensible heat flux?, Water Resour. Res., 45, W07418,

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Variance methods to estimate regional heat fluxes with aircraft measurements in the convective boundary layer

Cited by 6 publications

References 49 publications

Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia

Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia

Turbulent Flux Observations at the Tip of a Narrow Cape on Miyako Island in Japan's Southwestern Islands

How universal is the C function in the bulk atmospheric boundary layer similarity approach for estimating surface sensible heat flux?

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