Diurnal and inter-monthly variation of land surface heat fluxes over the central Tibetan Plateau area

Ma, Yaoming; Fan, Shuai; Ishikawa, Hirohiko; Tsukamoto, Osamu; Yao, Tandong; Koike, Takao; Zuo, Hongchao; Hu, Zeyong; Su, Zhongbo

doi:10.1007/s00704-004-0104-1

Cited by 88 publications

(93 citation statements)

References 29 publications

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“…Accordingly, aerodynamic roughness parameters in this site make a seasonal change, being governed by various aerodynamic and thermodynamic characteristics. Aerodynamic roughness over the Tibetan plateau was previously explored by various approaches such as traditional wind profile method using eddy covariance instruments, flux-variance method, and vegetation index (Choi et al, 2004;Ma et al, 2002Ma et al, , 2005Ma et al, , 2008Su, 2002Su, , 2005Yang et al, 2003Yang et al, , 2008.…”

Section: J H Lee Et Al: Calibrate Aerodynamic Roughnessmentioning

confidence: 99%

Calibration of aerodynamic roughness over the Tibetan Plateau with Ensemble Kalman Filter analysed heat flux

Lee

Timmermans

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract. Aerodynamic roughness height (Z om ) is a key parameter required in several land surface hydrological models, since errors in heat flux estimation are largely dependent on optimization of this input. Despite its significance, it remains an uncertain parameter which is not readily determined. This is mostly because of non-linear relationship in Monin-Obukhov similarity (MOS) equations and uncertainty of vertical characteristic of vegetation in a large scale. Previous studies often determined aerodynamic roughness using a minimization of cost function over MOS relationship or linear regression over it, traditional wind profile method, or remotely sensed vegetation index. However, these are complicated procedures that require a high accuracy for several other related parameters embedded in serveral equations including MOS. In order to simplify this procedure and reduce the number of parameters in need, this study suggests a new approach to extract aerodynamic roughness parameter from single or two heat flux measurements analyzed via Ensemble Kalman Filter (EnKF) that affords non-linearity. So far, to our knowledge, no previous study has applied EnKF to aerodynamic roughness estimation, while the majority of data assimilation study have paid attention to updates of other land surface state variables such as soil moisture or land surface temperature. The approach of this study was applied to grassland in semi-arid Tibetan Plateau and maize on moderately wet condition in Italy. It was demonstrated that aerodynamic roughness parameter can be inversely tracked from heat flux EnKF final analysis. The aerodynamic roughness height estimated in this approach was consistent with eddy covariance method and literature value. Through a calibration of this parameter, this adjusted the sensible heat previously overestimated and latent heat flux previously underestimated by the original Surface Energy Balance System (SEBS) model. It was considered that this improved heat flux estimation especially during the summer Monsoon period, based upon a comparison with precipitation and soil moisture field measurement. For an advantage of this approach over other previous methodologies, this approach is useful even when eddy covariance data are absent at a large scale and is time-variant over vegetation growth, as well as is not directly affected by saturation problem of remotely sensed vegetation index.

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Section: J H Lee Et Al: Calibrate Aerodynamic Roughnessmentioning

confidence: 99%

Calibration of aerodynamic roughness over the Tibetan Plateau with Ensemble Kalman Filter analysed heat flux

Lee

Timmermans

et al. 2012

Hydrol. Earth Syst. Sci.

Self Cite

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“…To understand the role of the Tibetan Plateau for the global heat and water budget, much effort has been put into the estimation of energy balance and turbulent flux measurements within international campaigns like GAME/Tibet (Global Energy and Water cycle Experiment Asian Monsoon Experiment) and CAME (Coordinated Enhanced Observing Period Asia-Australia Monsoon Project) (Xu and Haginoya 2001;Ma et al 2003;Ma et al 2005) and in the framework of the Tibetan Observation and Research Platform (Ma et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Biermann

Babel

et al. 2013

Theor Appl Climatol

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The Tibetan Plateau plays an important role in the global water cycle and is strongly influenced by climate change. While energy and matter fluxes have been more intensely studied over land surfaces, a large proportion of lakes have either been neglected or parameterised with simple bulk approaches. Therefore, turbulent fluxes were measured over wet grassland and a shallow lake with a single eddy-covariance complex at the shoreline in the Nam Co basin in summer 2009. Footprint analysis was used to split observations according to the underlying surface, and two sophisticated surface models were utilised to derive gap-free time series. Results were then compared with observations and simulations from a nearby eddy-covariance station over dry grassland, yielding pronounced differences. Observations and footprint integrated simulations compared well, even for situations with flux contributions including grassland and lake. The accessibility problem for EC measurements on lakes can be overcome by combining standard meteorological measurements at the shoreline with model simulations, only requiring representative estimates of lake surface temperature.

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“…The first is apparent diurnal variations due to strong solar radiation and low air density. The solar irradiance over the Plateau is often observed to exceed 1200 W m −2 near noon (Ma et al, 2005), which results in very strong diurnal change of the surface energy budget and near-surface meteorological variables. For instance, the diurnal range of the surface skin temperature can exceed 60 K. The second is the distinct seasonal march of the surface water and energy budget in the central and eastern TP.…”

Section: Introductionmentioning

confidence: 99%

Some practical notes on the land surface modeling in the Tibetan Plateau

Yang

Chen

Qin

2009

Hydrol. Earth Syst. Sci.

152

133

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Abstract. The Tibetan Plateau is a key region of landatmosphere interactions, as it provides an elevated heat source to the middle-troposphere. The Plateau surfaces are typically characterized by alpine meadows and grasslands in the central and eastern part while by alpine deserts in the western part. This study evaluates performance of three state-of-the-art land surface models (LSMs) for the Plateau typical land surfaces.

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Diurnal and inter-monthly variation of land surface heat fluxes over the central Tibetan Plateau area

Cited by 88 publications

References 29 publications

Calibration of aerodynamic roughness over the Tibetan Plateau with Ensemble Kalman Filter analysed heat flux

Calibration of aerodynamic roughness over the Tibetan Plateau with Ensemble Kalman Filter analysed heat flux

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Some practical notes on the land surface modeling in the Tibetan Plateau

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