Representation of the Canopy Conductance in Modeling the Surface Energy Budget for Low Vegetation

Ronda, R.J.; Bruin, H.A.R. de; Holtslag, A.A.M.

doi:10.1175/1520-0450(2001)040<1431:rotcci>2.0.co;2

Cited by 105 publications

(146 citation statements)

References 28 publications

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“…Two types of bulk canopy resistance models have been applied to express r s : the Noilhan-Planton (N-P) approach (Noilhan and Planton, 1989), also referred to as the Jarvis model (Jarvis, 1976), and the Jacobs-De Bruin (J-D) model (Jacobs and De Bruin, 1997;Ronda et al, 2001) also referred to as the Ball type model (Ball et al, 1987).…”

Section: The Bulk Canopy Resistance R Smentioning

confidence: 99%

“…The former relates the canopy resistance to environmental variables at an atmospheric reference height (Javis, 1976;Noilhan and Planton, 1989); the latter correlates canopy resistance to the assimilation rate (Ball et al, 1987;Leuning, 1995;Jacobs and De Bruin, 1997). Although these two types of models have been applied to various canopies and plants (Niyogi and Raman 1997;Ronda et al, 2001), there has been no comparison of the two types of models in terms of their application to the P-M model to simulate the actual ET of crop fields, especially in the arid area of northwest China. The functions and parameters of the models have yet to be evaluated in different studies and in different environmental conditions.…”

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confidence: 99%

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Evaluation of Penman-Monteith model applied to a maize field in the arid area of northwest China

Zhao

Ersi

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. The Penman-Monteith (P-M) model has been applied to estimate evapotranspiration in terrestrial ecosystem throughout the world. As shown in many studies, bulk canopy resistance is an especially important factor in the application of the P-M model. In this study, the authors used the Noilhan and Planton (N-P) approach and the Jacobs and De Bruin (J-D) approach to express the bulk canopy resistance. The P-M model was applied to a maize field using the two approaches in an arid area of northwest China and evaluated on the basis of measured half-hourly values from the eddy covariance system. The results indicate that the N-P approach slightly underestimates the bulk canopy resistance, while the J-D approach overestimates it. Over the entire maize growing season, the N-P approach yielded a more consistent estimate of bulk canopy resistance than did the J-D approach. Correspondingly, the P-M model with J-D bulk canopy resistance slightly underestimated the latent heat flux throughout the maize growing season, but overestimated the latent heat flux during the dry season as compared to the N-P approach results. The good fit between the simulated latent heat flux estimated by the P-M model using the N-P approach and the data measured at half-hour time steps demonstrates that the application of this approach is reasonable in relatively homogenous maize fields that are not drought-stressed. Further research to improve the performance of P-M model to simulate evapotranspiration in the cropped fields is discussed.

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Section: The Bulk Canopy Resistance R Smentioning

confidence: 99%

mentioning

confidence: 99%

Evaluation of Penman-Monteith model applied to a maize field in the arid area of northwest China

Zhao

Ersi

et al. 2010

Hydrol. Earth Syst. Sci.

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show abstract

“…An advantage of an A-g s model is that the calculations are based on simple plant characteristics, for example, whether the vegetation uses the C3 or C4 metabolism, and on atmospheric variables that are measured on a routine basis at a standard meteorological observation site. Recently, it was improved the approximation for the canopy conductance [7] as:…”

Section: The Excange Velocity Approach For the Transfer From Air To Pmentioning

confidence: 99%

“…with g min,w -cuticle conductance for water; LAI -leaf area index; C s -the CO 2 concentration at the leaf surface, (mg m −3 ) is the CO 2 compensation point, D s (Pa) is the vapour pressure deficit at plant level; f( r ) is correction for soil water stress and a 1 and D * are empirical quantities defined, as many other quantities needed in [7]. A g,c is the (unstressed) canopy gross assimilation rate (net of photorespiration for C3 crops) and is parameterized as in WOFOST crop growth model and adapted to local cultivars [8].…”

Section: The Excange Velocity Approach For the Transfer From Air To Pmentioning

confidence: 99%

Accidental release of tritiated water – toward a better radiological assessment

et al. 2009

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Abstract. The need of less conservative but reliable risk assessment for accidental tritium release was recognized in the frame of present debate on nuclear energy future. While the fusion reactor is only in research phase and risk assessment are not extremely stringent, Romania faces a debate on near future of nuclear energy with heavy water reactors, known to have a large load and release of tritium. Both tritium and 14 C are key radionuclide for CANDU and are also directly involved in the life cycle of plants and animals. An interdisciplinary approach is proposed in order to better handle the environmental transfer of tritium under accidental conditions and preparatory steps are presented.

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“…Jacobs (1994) deduced the parameterizations assuming plant roots were deep and plants did not suffer from water stress during the observations. Calvet et al (1998) and Ronda, Bruin and Holtslag (2001) proposed modifications that take into account the relationships between soil water content and mesophyll conductance g m and the gross assimilation rate of CO 2 A g , respectively. These relationships, usually linear, were developed based on empirical considerations and, therefore, fail to describe the responses of plants to soil water content in a mechanistic way.…”

Section: Plant-atmosphere Transfer Modelsmentioning

confidence: 99%

Mecanismos de transferência de água entre solo, planta e atmosfera e sua relação com o estresse hídrico vegetal

Durigon¹

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Aos meus pais, Mariangela e José Eugênio, dedico.Parametrizações mecanísticas descrevem fisicamente a interação das plantas com o ambiente baseando-se em processos fundamentais, como assimilação de líquida de CO 2 e extração da água do solo pelas raízes, influenciados pelas condições do ambiente. O objetivo principal dessas rotinas é aumentar o entendimento do sistema estudado pela integração quantitativa e qualitativa do conhecimento em um modelo de simulação dinâmica do sistema real. Definindo estresse hídrico como a condição em que uma planta aumenta a resistência estomática em conseqüência do aumento da demanda atmosférica e/ou da redução da disponibilidade hídrica no solo, tem-se como hipótese que o déficit hídrico em plantas é causado por fatores ambientais relacionados com as interfaces solo-raiz e folha-atmosfera. O objetivo geral desse estudo é identificar quais são as variáveis do solo e da atmosfera determinantes e que devem ser consideradas na modelagem da deficiência hídrica em plantas. Os teores de água no solo e na atmosfera foram monitorados em condições de campo durante o desenvolvimento da cultura de feijão (Phaseolus vulgaris L.) entre Junho e Setembro de 2010, e correlacionados ao estresse hídrico caracterizado por medições de temperatura do dossel. As variáveis de interesse, especificamente o potencial matricial da água do solo, a temperatura e a umidade do ar e a temperatura do dossel foram medidas regularmente em intervalos de 30 minutos. A taxa de transpiração e a condutância estomática foram medidas ocasionalmente. Uma parcela foi irrigada durante todo o ciclo da cultura (tratamento totalmente irrigada), enquanto a outra foi submetida ao estresse hídrico na fase reprodutiva (tratamento com déficit de irrigação). A metodologia utilizada neste estudo deu suporte à hipótese inicial. Os principais fatores relacionados à interface solo-raiz são as propriedades hidráulicas do solo, especialmente a condutividade hidráulica e da densidade de comprimento radicular; na interface atmosfera de folhas, os fatores mais importantes são o déficit de pressão de vapor do ar atmosférico VPD. Estes fatores devem ser considerados de alguma forma na modelagem estresse hídrico em plantas. A detecção da ocorrência de estresse hídrico nas plantas no tratamento com déficit de irrigação foi feito por comparações entre o VPD e diferença de temperatura entre o dossel e o ar Δt dossel-ar e entre t dossel e a temperatura do bulbo úmido t wb dos dois tratamentos hídricos. O início do estresse hídrico nas plantas com déficit de irrigação ocorreu em 05 de Agosto. As simulações com os modelos mecanísticos de extração da água do solo pelas raízes proposto por Jong van Lier et al. (2008) e de assimilação de CO 2 proposto por Jacobs (1994) foram feitos com os dados de ambos os tratamentos. O modelo de extração foi sensível aos parâmetros hidráulicos do solo, especialmente a condutividade hidráulica e o comprimento radicular. A taxa de transpiração estimada pelo modelo de Jacobs (1994) mostrou-se dependente da temperatura do...

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Representation of the Canopy Conductance in Modeling the Surface Energy Budget for Low Vegetation

Cited by 105 publications

References 28 publications

Evaluation of Penman-Monteith model applied to a maize field in the arid area of northwest China

Evaluation of Penman-Monteith model applied to a maize field in the arid area of northwest China

Accidental release of tritiated water – toward a better radiological assessment

Mecanismos de transferência de água entre solo, planta e atmosfera e sua relação com o estresse hídrico vegetal

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