Apparent soil thermal diffusivity, a case study: HAPEX-Sahel experiment

Silans, Alain; Monteny, Bruno; Lhomme, Jean

doi:10.1016/0168-1923(95)02323-2

Cited by 44 publications

(10 citation statements)

References 11 publications

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“…In early research, the temperature of homogeneous soil was derived using the heat diffusion equation under periodic forcing at the soil surface (Bhumralkar 1975). More recently, soil heat transfer has been attributed to a complex combination of conductive and intraporous convective processes (Passerat De Silans et al 1996), leading to the development of solutions for the thermal conduction-convection equation (Gao et al 2003;Shao et al 1998). A number of prior observations have shown that temperature gradients will subsequently affect flow and heat transfer in soil, thus demonstrating that soil water flow and heat flow are interdependent (Wang 2007).…”

Section: Introductionmentioning

confidence: 99%

An improved model for soil surface temperature from air temperature in permafrost regions of Qinghai-Xizang (Tibet) Plateau of China

Zhao

et al. 2016

Meteorol Atmos Phys

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Soil temperature plays a key role in hydro-thermal processes in environments and is a critical variable linking surface structure to soil processes. There is a need for more accurate temperature simulation models, particularly in Qinghai-Xizang (Tibet) Plateau (QXP). In this study, a model was developed for the simulation of hourly soil surface temperatures with air temperatures. The model incorporated the thermal properties of the soil, vegetation cover, solar radiation, and water flux density and utilized field data collected from Qinghai-Xizang (Tibet) Plateau (QXP). The model was used to simulate the thermal regime at soil depths of 5 cm, 10 cm and 20 cm and results were compared with those from previous models and with experimental measurements of ground temperature at two different locations. The analysis showed that the newly developed model provided better estimates of observed field temperatures, with an average mean absolute error (MAE), root mean square error (RMSE), and the normalized standard error (NSEE) of 1.17°C, 1. 30°C and 13.84 %, 0.41°C, 0.49°C and 5.45 %, 0.13°C, 0.18°C and 2.23 % at 5 cm, 10 cm and 20 cm depths, respectively. These findings provide a useful reference for simulating soil temperature and may be incorporated into other ecosystem models requiring soil temperature as an input variable for modeling permafrost changes under global warming.

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Section: Introductionmentioning

confidence: 99%

An improved model for soil surface temperature from air temperature in permafrost regions of Qinghai-Xizang (Tibet) Plateau of China

Zhao

et al. 2016

Meteorol Atmos Phys

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“…Devido à ordem de grandeza dos valores as "pequenas" divergências não comprometem os métodos, contudo, se faz necessário que os estudos a respeito dessa temática continuem sendo realizados na busca de desenvolver novos métodos e aprimorar os já existentes. De acordo com Silans et al (1999), o método Harmônico proporciona bons resultados quando a condição de estabilidade da periodicidade é satisfeita, no entanto, durante dias com condições climáticas muito variáveis o mesmo deve ser substituído pelo método da Transformada de Laplace corrigida.…”

Section: Resultsunclassified

Características térmicas do solo observadas em cidades distintas do estado da Paraiba

Diniz¹,

Rafael²,

Filho³

et al. 2013

Revista Verde

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Resumo: A variação da temperatura do solo que uma planta consegue suportar é relativamente ampla, no entanto, seu desenvolvimento é seriamente comprometido a partir do momento em que solo passa a assumir temperaturas abaixo ou acima de certos valores limites. Até então, embora se saiba que a temperatura do solo é um dos fatores ambientais de maior importância para agricultura, poucos estudos acerca dessa variável foram realizados pela comunidade científica para os solos da região Nordeste do Brasil. Logo, o presente trabalho tem como objetivo o estudo das características térmicas do solo, a partir de dados coletados em duas cidades distintas do estado da Paraíba. Com base na análise dos resultados, verificou-se que o comportamento térmico do solo de ambas as cidades são bastante semelhantes, especialmente no que diz respeito às horas e aos meses de ocorrência das máximas e mínimas temperaturas. Á medida que se avança em profundidade constatou-se uma progressiva diminuição da variabilidade diária das temperaturas do solo. As estimativas da difusividade térmica do solo, obtidas mediante o emprego do método da amplitude e logarítmico, apresentaram satisfatória concordância. Palavras-chave:Temperatura do solo, difusividade térmica, Paraíba, Nordeste do Brasil.Abstract: The variation of soil temperature which a plant will tolerate is often quite broad, however, its development is seriously compromised from the moment in that the soil begins to assume temperatures below or above certain limits. Until then, although it is known that soil temperature is one of environmental factor of greatest importance to agriculture, few studies on this variable were performed by the scientific community for soils of Northeastern Brazil. Therefore, this work aims the study of soil thermal characteristics, from data collected in two different cities in the state of Paraíba. Based on the analysis of the results, it was found that the soil thermal behavior of both cities is quite similar, especially with respect to the hours and months of occurrence of maximum and minimum temperatures. It was found a progressive decrease of daily variability of soil temperatures as it advances in depth. The estimates of soil thermal diffusivity, obtained by employing the method of amplitude and logarithmic, showed satisfactory agreement.

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“…Its difference to the generalized approach was that it assumed soil temperature and soil heat flux varied harmonically with time. This hypothesis is not always fulfilled, particularly in regions where abrupt weather change occurs within a short time, for example, during the crossover of a cold front [33]. Furthermore, the H-W approach requires determination of harmonics number.…”

Section: Evaluation Of Three Approachesmentioning

confidence: 98%

Linking Surface Temperature Based Approaches for Estimating Soil Heat Flux with Error Propagation

Lu¹,

Liu²,

Hiyama³

2014

ACS

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Soil heat flux is an inseparable component of the surface energy balance. Accurate estimation of regional soil heat flux is valuable to studies of meteorology and hydrology. Conventional measurement of using soil heat flux plates at the site scale is impractical to estimate large-scale flux. Other approaches generally require soil temperature to be measured in at least two soil layers, which is also difficult to implement at the regional scale. In the last decade, single-layer based approaches were developed to fulfill the regional requirement. This study used a simple but more general approach for estimating soil heat flux solely with surface temperature. The generalized approach can be conditionally linked to two existing single-layer based approaches but has fewer restrictions or assumptions. Error analysis revealed that measurement error in surface temperature would have limited effects on soil heat flux estimated from the new approach. Model simulations showed that soil heat flux estimated from the approach agreed with those simulated from the heat transfer equation. Furthermore, case examinations at two sites with contrasting climate regimes demonstrated that the generalized approach had better performance than the existing single-layer approaches. It achieved the highest correlation of determination and the lowest mean, standard deviation, and root mean squared error of the differences between the estimates and the field measures at either site. The generalized approach can estimate soil heat flux at a depth but it requires only surface temperature data as input, which is an advantage to remote sensing applications.

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Apparent soil thermal diffusivity, a case study: HAPEX-Sahel experiment

Cited by 44 publications

References 11 publications

An improved model for soil surface temperature from air temperature in permafrost regions of Qinghai-Xizang (Tibet) Plateau of China

An improved model for soil surface temperature from air temperature in permafrost regions of Qinghai-Xizang (Tibet) Plateau of China

Características térmicas do solo observadas em cidades distintas do estado da Paraiba

Linking Surface Temperature Based Approaches for Estimating Soil Heat Flux with Error Propagation

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