Surface layer similarity in the nocturnal boundary layer: the application of Hilbert-Huang transform

Hong, Jinkyu; Kim, J.; Ishikawa, Hirohiko; Ma, Yunheng

doi:10.5194/bg-7-1271-2010

Cited by 19 publications

(14 citation statements)

References 44 publications

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“…Compared to Fourier-based filters and wavelet decompositions, the empirical mode decomposition (EMD) is adaptive and has high locality, and therefore capable of handling some of the non-linear and non-stationary occurrences that are ubiquitous in turbulence data (Huang et al 1998, Huang andWu 2008). EMD has been favored in several atmospheric boundary layer (ABL) studies (Hong et al 2010, Barnhart et al 2012, Wang et al 2013, Gao et al 2016. The ensemble empirical mode decomposition (EEMD) (Wu and Huang 2009), a method based on EMD (Huang et al 1998, Huang andWu 2008) for time series analysis, was adopted here.…”

Section: Ensemble Empirical Mode Decomposition (Eemd)mentioning

confidence: 99%

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

Gao

Katul

et al. 2017

Environ. Res. Lett.

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It is now accepted that large-scale turbulent eddies impact the widely reported non-closure of the surface energy balance when latent and sensible heat fluxes are measured using the eddy covariance method in the atmospheric surface layer (ASL). However, a mechanistic link between large eddies and non-closure of the surface energy balance remains a subject of inquiry. Here, measured 10 Hz time series of vertical velocity, air temperature, and water vapor density collected in the ASL are analyzed for conditions where entrainment and/or horizontal advection separately predominate. The series are decomposed into small-and large-eddies based on a frequency cutoff and their contributions to turbulent fluxes are analyzed. Phase difference between vertical velocity and water vapor density associated with large eddies reduces latent heat fluxes, especially in conditions where advection prevails. Enlarged phase difference of large eddies linked to entrainment or advection occurrence leads to increased residuals of the surface energy balance.

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Section: Ensemble Empirical Mode Decomposition (Eemd)mentioning

confidence: 99%

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

Gao

Katul

et al. 2017

Environ. Res. Lett.

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“…Land surface modelling of energy and carbon dioxide exchange faces specific problems on the Tibetan Plateau. Most influential is the strong diurnal cycle of the surface temperature, observed in dry conditions over bare soil or very low vegetation, leading to overestimation of surface sensible heat flux (Yang et al, 2009;Hong et al, 2010) caused by too high turbulent diffusion coefficients. Land surface models usually parameterise these coefficients by a fixed fraction between the roughness length of momentum and heat, however, Yang et al (2003) and Ma et al (2002) observed a diurnal variation of the thermal roughness length on the Tibetan Plateau.…”

Section: Problems Of Land Surface Modelling On the Tibetan Plateaumentioning

confidence: 99%

Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

Babel

Biermann

Coners³

et al. 2014

Biogeosciences

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Abstract. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.

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“…Land surface modelling of energy and carbon dioxide exchange faces specific problems on the Tibetan Plateau due to its high elevation and semi-arid conditions: a strong diurnal cycle of the surface temperature (Yang et al, 2009;Hong et al, 2010), a diurnal variation of the thermal roughness length observed on the Tibetan Plateau (Ma et al, 2002;Yang et al, 2003), and high bare soil evaporation in semiarid areas (e.g. Agam et al, 2004;Balsamo et al, 2011).…”

Section: Soil-vegetation-atmosphere Transfer Modelsmentioning

confidence: 99%

Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

Foken¹

2014

Preprint

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Abstract. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments coupling changes of surface properties and processes with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan plateau. We coupled measurements of micro-lysimeter, chamber, 13C labeling, and eddy-covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyze how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while the total sum of evapotranspiration remains unaffected. The results show an earlier onset of convection and cloud generation, likely triggered by enhanced evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a~significant influence on larger scales.

show abstract

Surface layer similarity in the nocturnal boundary layer: the application of Hilbert-Huang transform

Cited by 19 publications

References 44 publications

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies

Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

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