Influence of soil water content on the thermal infrared emissivity of bare soils: Implication for land surface temperature determination

Mira, M.; Valor, E.; Boluda, Rafael; Caselles, Vicente; Coll, César

doi:10.1029/2007jf000749

Cited by 131 publications

(101 citation statements)

References 20 publications

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“…2). Generally, studies that handled the effect of soil moisture on emissivity are few and agree that emissivity increases when the soil moisture increases (Salisbury and Daria, 1992;Mira et al, 2007). Moreover, it was found (Hulley et al, 2010) that a decrease in emissivity of 10 % will result in a decrease in net longwave radiation of only 7 W m −2 .…”

Section: Theorymentioning

confidence: 99%

Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

Al-Khaier

Flerchinger

2012

Hydrol. Earth Syst. Sci.

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Abstract. Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

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Section: Theorymentioning

confidence: 99%

Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

Al-Khaier

Flerchinger

2012

Hydrol. Earth Syst. Sci.

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“…ε is the land surface emissivity estimated by Consoli and Vanella [16]. ε c is the emissivity of vegetation and ε s is the emissivity of the soil surface, which can depend on the soil moisture [11,22]. In addition, some representative values for ε c and ε s can be retrieved from the look-up tables compiled by Rubio et al [23] in the absence of measured values.…”

Section: Methodsmentioning

confidence: 99%

“…The plant moisture constraint, f m , was estimated from the relative change in light absorptance according Equation (22), assuming that light absorptance varies primarily in response to moisture stress [29]. f ARAR is the fraction of absorbed photosynthetically active radiation and can be acquired from MODIS standard products or calculated as a function of vegetation indexes [28].…”

Section: Methodsmentioning

confidence: 99%

Estimating Evapotranspiration from an Improved Two-Source Energy Balance Model Using ASTER Satellite Imagery

Zhuang

2015

Water

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Abstract:Reliably estimating the turbulent fluxes of latent and sensible heat at the Earth's surface by remote sensing is important for research on the terrestrial hydrological cycle. This paper presents a practical approach for mapping surface energy fluxes using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images from an improved two-source energy balance (TSEB) model. The original TSEB approach may overestimate latent heat flux under vegetative stress conditions, as has also been reported in recent research. We replaced the Priestley-Taylor equation used in the original TSEB model with one that uses plant moisture and temperature constraints based on the PT-JPL model to obtain a more accurate canopy latent heat flux for model solving. The collected ASTER data and field observations employed in this study are over corn fields in arid regions of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) area, China. The results were validated by measurements from eddy covariance (EC) systems, and the surface energy flux estimates of the improved TSEB model are similar to the ground truth. A comparison of the results from the original and improved TSEB models indicates that the improved method more accurately estimates the sensible and latent heat fluxes, generating more precise daily evapotranspiration (ET) estimate under vegetative stress conditions.

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“…Mira et al [54] stressed the importance of an accurate determination of emissivity variations in soil water content to allow for suitable temperature retrievals for sandy soils, which show the greatest levels of variation, as well as for a variety of soils with different soil textures. According to these studies, we assumed the emissivity of bare soil to be 0.96 in our study.…”

Section: Emissivity Determinationmentioning

confidence: 99%

Identifying the Lambertian Property of Ground Surfaces in the Thermal Infrared Region via Field Experiments

Qin

Yang

et al. 2017

Remote Sensing

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Abstract:Lambertian surfaces represent an important assumption when constructing thermal radiance transfer equations for remote sensing observations of ground surface temperatures. We identify the properties of ground surfaces in thermal infrared regions as Lambertian surfaces via field experiments. Because Lambertian surfaces present homogeneous thermal emissions levels in hemispheric directions for a specific ground surface under specific kinetic temperatures and emissions, we conducted a series of field experiments to illustrate the properties of such ground surfaces. Four typical ground surfaces were selected for the experiments to observe thermal emissions: bare soil, grass, water, and concrete. Radiance thermometers were used to observe ground emissions from seven directions: 30 • , 45 • , 60 • , 90 • , 120 • , 135 • , and 150 • . Solar zenith angles were considered for the observation of ground emissions. Experiments were conducted in five different regions of China (Beijing, Nanjing, Xilinguole, Yongzhou, and Jiangmen) during both daytime and nighttime. To determine whether different observation angles have significantly different effects on radiance, statistical analyses (ANOVA and Friedman test) were conducted. Post hoc multiple comparison tests and pairwise multiple comparisons were also conducted to examine the various pairings of observation angles and to measure the radiance differences. Roughly half of the radiance groups of all observed sites were tested via an ANOVA, and the remaining groups with unequal variances were subjected to the Friedman test. The results indicate that statistically significant differences in the radiance levels occurred among the seven angles for almost all of the sites (39 of the 40 groups). The results of our experiments indicate that the selected ground surfaces, especially the grass and the bare soil, may not behave with Lambertian properties in the thermal infrared region. This is probably attributed to the roughness of the selected surface, because we found that roughness is an important factor affecting the observed magnitude of thermal emission from different directions of the ground surface under study. Therefore, whether or not a terrestrial surface can be assumed to be a Lambertian surface should be based on their geometric structure. When the surface is relatively smooth, we can say that it is close to the Lambertian property in thermal emission.

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Influence of soil water content on the thermal infrared emissivity of bare soils: Implication for land surface temperature determination

Cited by 131 publications

References 20 publications

Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

Estimating Evapotranspiration from an Improved Two-Source Energy Balance Model Using ASTER Satellite Imagery

Identifying the Lambertian Property of Ground Surfaces in the Thermal Infrared Region via Field Experiments

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