Results from the Push Broom Microwave Radiometer flights over the Konza Prairie in 1985

Schmugge, Thomas J.; Wang, J.R.; Asrar, Ghassem

doi:10.1109/36.7684

Cited by 82 publications

(18 citation statements)

References 6 publications

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“…Not only may the vegetation layer of tree canopy and understory be relatively dense, but in this type of environment, a litter layer is often an additional cover of the mineral soil. Studies over grasslands [9]- [11] have hinted at the fact that this layer could highly attenuate soil emission, although radiative transfer properties of litter are still largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Calibration of the L-MEB Model Over a Coniferous and a Deciduous Forest

Grant

Saleh-Contell

Wigneron³

et al. 2008

IEEE Trans. Geosci. Remote Sensing

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Abstract-In this paper, the L-band Microwave Emission of the Biosphere (L-MEB) model used in the Soil Moisture and Ocean Salinity (SMOS) Level 2 Soil Moisture algorithm is calibrated using L-band (1.4 GHz) microwave measurements over a coniferous (Pine) and a deciduous (mixed/Beech) forest. This resulted in working values of the main canopy parameters optical depth (τ ), single scattering albedo (ω), and structural parameters tt(H) and tt(V), besides the soil roughness parameters H R and N R . Using these calibrated values in the forward model resulted in a root mean-square error in brightness temperatures from 2.8 to 3.8 K, depending on data set and polarization. Furthermore, the relationship between canopy optical depth and leaf area index is investigated for the deciduous site. Finally, a sensitivity study is conducted for the focus parameters, temperature, soil moisture, and precipitation. The results found in this paper will be integrated in the operational SMOS Level 2 Soil Moisture algorithm and used in future inversions of the L-MEB model, for soil moisture retrievals over heterogeneous, partly forested areas.Index Terms-Forest, L-band, microwave radiometry, soil moisture, Soil Moisture and Ocean Salinity (SMOS).

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Section: Introductionmentioning

confidence: 99%

Calibration of the L-MEB Model Over a Coniferous and a Deciduous Forest

Grant

Saleh-Contell

Wigneron³

et al. 2008

IEEE Trans. Geosci. Remote Sensing

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“…5 is that it clearly shows that the contributions of both the litter and the grass layers to overall radiance are important. In a previous study [8], the thatch structure of an unburned grass cover was found to result in very high emissivities and low sensitivity to moisture status of the underlying soil. A later study over grass [9] found a similar effect for a "mixed layer" consisting of mulch, plant debris, and a tight layer of grass roots and stems, particularly when wet; however, the respective contributions of these components could not be separated.…”

Section: Forest Floor Emissivitiesmentioning

confidence: 87%

“…Ten years ago, a study over prairie grass [8] was the first to note that the thatched layer of dead vegetation in unburned grass areas has a considerable impact on L-band emission when wet. The issue was taken up again recently [9] to confirm that, compared to a living grass layer, a mixed layer of dead grass and mulch shows an increased optical depth with higher moisture.…”

mentioning

confidence: 99%

Observations and Modeling of a Pine Forest Floor at L-Band

Grant

Griend²,

Schwank³

et al. 2009

IEEE Trans. Geosci. Remote Sensing

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Abstract-Recent studies of passive L-band observations over forests have shown that the average canopy transmissivity in temperate coniferous and deciduous forests is on the order of 0.4-0.5. Although the canopy would therefore be expected to transmit a reasonable amount of ground emission, the total emission observed above the canopy shows very little variation with varying soil moisture content. Moist litter present on the forest floor is known to obscure the soil emission. Therefore, more knowledge on the L-band radiative properties of litter and understory layers is needed to better understand the emission of the whole forest system. In order to contribute toward this issue, a field experiment was conducted in a pine forest in southwest France. Radiometric observations were done on the canopy and on different configurations of the forest floor, following sequential stripping of each forest floor layer. In combination with a long-term data set of abovecanopy observations, this resulted in emissivity values of bare soil, soil-litter, soil-litter-grass, and soil-litter-grass-canopy configurations for a range of soil and litter moisture values. Calculations involved the use of the Wilheit and L-MEB models. The sensitivity to soil moisture was found to be substantially suppressed by the presence of a grass understory and litter. This corroborates the low correlation between soil moisture and L-band brightness temperature measured above the canopy. Several results of recent modeling and laboratory studies are also confirmed by this paper, which is, to our knowledge, the first to use in situ experimental data in this context.

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“…The field of view is 1.2 times the altitude which was 300 m in MACHYDRO'90. For a detailed description of the PBMR, see Schmugge et al (1988).…”

Section: Passive Microwave Radiometermentioning

confidence: 99%

Intercomparisons between passive and active microwave remote sensing, and hydrological modeling for soil moisture

Wood

Lin

Mancini

et al. 1993

Advances in Space Research

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Soil moisture estimates from a distributed hydrological model and two microwave remote sensors (Push Broom Microwave Radiometer and Synthetic Aperture Radar) were compared with the ground measurements collected during the MAC-HYDRO'90 experiment over a 7.4-km 2 watershed in central Pennsylvania. Various information, including rainfall, soil properties, land cover, topography and remote sensing imagery, were integrated and analyzed using an image integration technique. It is found that the hydrological model and both microwave sensors successfully pick up the temporal variation of soil moisture. Results also indicate the spatial soil moisture pattern can be remotely sensed within reasonable accuracy using existing algorithms. Watershed averaged soil moisture estimates from the hydrological model are wetter than remotely sensed data. It is difficult to conclude which instrument yield better performance for the studied case. The choice will be based on the intended applications and information that is available.

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Results from the Push Broom Microwave Radiometer flights over the Konza Prairie in 1985

Cited by 82 publications

References 6 publications

Calibration of the L-MEB Model Over a Coniferous and a Deciduous Forest

Calibration of the L-MEB Model Over a Coniferous and a Deciduous Forest

Observations and Modeling of a Pine Forest Floor at L-Band

Intercomparisons between passive and active microwave remote sensing, and hydrological modeling for soil moisture

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