Comparison of seasonal and spatial variations of leaf area index and fraction of absorbed photosynthetically active radiation from Moderate Resolution Imaging Spectroradiometer (MODIS) and Common Land Model

Tian, Yuhong; Dickinson, Robert E.; Zhou, Lei; Zeng, Xubin; Dai, Yongjiu; Myneni, Ranga B.; Knyazikhin, Yuri; Zhang, X.; Friedl, M. A.; Yu, Hongbin; Wu, Wanru; Shaikh, Muhammad

doi:10.1029/2003jd003777

Cited by 123 publications

(99 citation statements)

References 24 publications

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“…To achieve credible results, these models must be systematically parameterized, calibrated and evaluated using independent observations at multiple spatial and temporal scales [13][14][15]. The rapidly increasing availability of remote sensing data has created unique opportunities for validating and improving these land surface models, especially at global and regional scales [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009

et al. 2013

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Using a recent Leaf Area Index (LAI) dataset and the Community Land Model version 4 (CLM4), we investigated percent changes and controlling factors of global vegetation growth for the period 1982 to 2009. Over that 28-year period, both the remote-sensing estimate and model simulation show a significant increasing trend in annual vegetation growth. Latitudinal asymmetry appeared in both products, with small increases in the Southern Hemisphere (SH) and larger increases at high latitudes in the Northern Hemisphere (NH). The south-to-north asymmetric land surface warming was assessed to be the principal driver of this latitudinal asymmetry of LAI trend. Heterogeneous precipitation functioned to decrease this latitudinal LAI gradient, and considerably regulated the local LAI change. A series of factorial experiments were specially-designed to isolate and quantify contributions to LAI trend from different external forcings such as climate variation, CO 2 , nitrogen deposition and land use and land cover change. The climate-only simulation confirms that climate change, particularly the asymmetry of land temperature variation, can explain the latitudinal pattern of LAI change. CO 2 fertilization during the last three decades was simulated to be the dominant cause for the enhanced vegetation growth. Our study, though limited by observational and modeling uncertainties, adds further insight into vegetation growth trends and environmental OPEN ACCESSRemote Sens. 2013, 5 1485 correlations. These validation exercises also provide new quantitative and objective metrics for evaluation of land ecosystem process models at multiple spatio-temporal scales.

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Section: Introductionmentioning

confidence: 99%

Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009

et al. 2013

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“…More detailed simulations are needed to validate the estimates derived in this study, particularly as improved models (Dai et al 2003;Tian et al 2004) and accurate high resolution surface albedo data (Justice et al 1998;Schaaf et al 2002) are now becoming available. Higher resolution coupled modelling using GCM and RCM methodologies and accurately measured location-specific urban and grassland surface albedo values, remains desirable.…”

Section: Discussionmentioning

confidence: 99%

Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study

Hamwey¹

2006

Mitig Adapt Strat Glob Change

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Abstract:To date, international efforts to mitigate climate change have focussed on reducing emissions of greenhouse gases in the energy, transportation and agriculture sectors, and on sequestering atmospheric carbon dioxide in forests. Here, the potential to complement these efforts by actions to enhance the reflectance of solar insolation by the human settlement and grassland components of the Earth's terrestrial surface is explored. Preliminary estimates derived using a static two dimensional radiative transfer model indicate that such efforts could amplify the overall planetary albedo enough to offset the current global annual average level of radiative forcing caused by anthropogenic greenhouse gases by as much as 30% or 0.76 Wm -2 .Terrestrial albedo amplification may thus extend, by about 25 years, the time available to advance the development and use of low-emission energy conversion technologies which ultimately remain essential to mitigate long-term climate change. While a scoping analysis indicates the technical feasibility of sufficiently enhancing human settlement and grassland albedos to levels needed to achieve reductions in radiative forcing projected here, additional study is required on two fronts. Firstly, the modelled radiative forcing reductions are static estimates. As they would generate climate feedbacks, more detailed dynamic climate modelling would be needed to confirm the stationary value of the radiative forcing reduction that would result from land surface albedo amplification. Secondly, land surface albedo amplification schemes may have important economic and environmental impacts. Accurate ex ante impact assessments would be required to validate global implementation of related measures as a viable mitigation strategy.

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“…For this study, we have conducted experiments using the BiosphereAtmosphere Transfer Scheme (BATS; Dickinson et al, 1993;Yang et al, 1997) as the option for snow surface albedo. We have also used the Canadian Land Surface Scheme (CLASS; Verseghy, 1991;Verseghy et al, 1993) with new vegetation parameters for testing model performance of albedo. In terms of the albedo options in the Noah-MP, the CLASS scheme simply computes the overall snow albedo depending on fresh snow albedo and snow age while the BATS one calculates snow albedo for direct and diffuse radiation in visible and near-infrared broadband accounting for several additional parameters such as grain size growth, impurity, and especially solar zenith angle (SZA) .…”

Section: The Noah-mpmentioning

confidence: 99%

Parameterization of the snow-covered surface albedo in the Noah-MP Version 1.0 by implementing vegetation effects

Park

2016

Geosci. Model Dev.

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Abstract. Snow-covered surface albedo varies depending on many factors, including snow grain size, snow cover thickness, snow age, forest shading factor, etc., and its parameterization is still under great uncertainty. For the snow-covered surface condition, albedo of forest is typically lower than that of short vegetation; thus snow albedo is dependent on the spatial distributions of characteristic land cover and on the canopy density and structure. In the Noah land surface model with multiple physics options (Noah-MP), almost all vegetation types in East Asia during winter have the minimum values of leaf area index (LAI) and stem area index (SAI), which are too low and do not consider the vegetation types. Because LAI and SAI are represented in terms of photosynthetic activeness, stem and trunk in winter are not well represented with only these parameters. We found that such inadequate representation of the vegetation effect is mainly responsible for the large positive bias in calculating the winter surface albedo in the Noah-MP. In this study, we investigated the vegetation effect on the snow-covered surface albedo from observations and improved the model performance by implementing a new parameterization scheme. We developed new parameters, called leaf index (LI) and stem index (SI), which properly manage the effect of vegetation structure on the snow-covered surface albedo. As a result, the Noah-MP's performance in the winter surface albedo has significantly improved -the root mean square error is reduced by approximately 69 %.

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Comparison of seasonal and spatial variations of leaf area index and fraction of absorbed photosynthetically active radiation from Moderate Resolution Imaging Spectroradiometer (MODIS) and Common Land Model

Cited by 123 publications

References 24 publications

Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009

Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009

Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study

Parameterization of the snow-covered surface albedo in the Noah-MP Version 1.0 by implementing vegetation effects

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