MODTRAN4: radiative transfer modeling for remote sensing

Anderson, Gail P.; Berk, Alexander; Acharya, Prabhat K.; Matthew, Michael W.; Bernstein, Lawrence S.; Chetwynd, James H.; Dothe, H.; Adler‐Golden, Steven M.; Ratkowski, Anthony J.; Felde, Gerald W.; Gardner, James A.; Hoke, Michael L.; Richtsmeier, Steven C.; Pukall, Brian; Mello, Jason B.; Jeong, Laila S.

doi:10.1117/12.410338

Cited by 85 publications

(56 citation statements)

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“…Each spectro-radiometer was connected to a fibre optic, which looks down to the vegetation at nadir with a field of view corresponding to a measured area of 2 m diameter. Vegetation and reference spectra were atmospherically corrected for the difference in altitude between ground and the reference panel using MODTRAN 4 [36]. The signal acquired on the vegetation was corrected to compensate for the absorption of the atmosphere along the path from vegetation to sensor, and the signal acquired on the reference board was corrected for the lack of absorption of incident light from the reference altitude to the ground.…”

Section: Instrumental Setup and Retrieval Of Fluorescencementioning

confidence: 99%

Gross Primary Production of a Wheat Canopy Relates Stronger to Far Red Than to Red Solar-Induced Chlorophyll Fluorescence

et al. 2017

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Sun-induced chlorophyll fluorescence (SIF) is a radiation flux emitted by chlorophyll molecules in the red (RSIF) and far red region (FRSIF), and is considered as a potential indicator of the functional state of photosynthesis in remote sensing applications. Recently, ground studies and space observations have demonstrated a strong empirical linear relationship between FRSIF and carbon uptake through photosynthesis (GPP, gross primary production). In this study, we investigated the potential of RSIF and FRSIF to represent the functional status of photosynthesis at canopy level on a wheat crop. RSIF and FRSIF were continuously measured in the O 2 -B (SIF687) and O 2 -A bands (SIF760) at a high frequency rate from a nadir view at a height of 21 m, simultaneously with carbon uptake using eddy covariance (EC) techniques. The relative fluorescence yield (Fyield) and the photochemical yield were acquired at leaf level using active fluorescence measurements. SIF was normalized with photosynthetically active radiation (PAR) to derive apparent spectral fluorescence yields (ASFY687, ASFY760). At the diurnal scale, we found limited variations of ASFY687 and ASFY760 during sunny days. We also did not find any link between Fyield and light use efficiency (LUE) derived from EC, which would prevent SIF from indicating LUE changes. The coefficient of determination (r 2 ) of the linear regression between SIF and GPP is found to be highly variable, depending on the emission wavelength, the time scale of observation, sky conditions, and the phenological stage. Despite its photosystem II (PSII) origin, SIF687 correlates less than SIF760 with GPP in any cases. The strongest SIF-GPP relationship was found for SIF760 during canopy growth. When canopy is in a steady state, SIF687 and SIF760 are almost as effective as PAR in predicting GPP. Our results imply some constraints in the use of simple linear relationships to infer GPP from SIF, as they are expected to be better predictive with far red SIF for canopies with a high dynamic range of green biomass and a low LUE variation range.

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Section: Instrumental Setup and Retrieval Of Fluorescencementioning

confidence: 99%

Gross Primary Production of a Wheat Canopy Relates Stronger to Far Red Than to Red Solar-Induced Chlorophyll Fluorescence

et al. 2017

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“…4-10 and 12) are 30-40 min averages of scores of individual photographs, and so these maps are dominated by only the most persistent cloud inhomogeneities. In particular, advection of the cloud field above our site greatly reduces each L rel map's range of averaged h and thus its horizontal gradients of h. This pronounced smoothing lets us realistically adapt an explicitly horizontally homogeneous model such as MODTRAN4 [43] to estimate how changes in h might affect the angular distribution of overcast L.…”

Section: Cloud Thickness Gradients and Overcast Brightness Asymmetriesmentioning

confidence: 99%

Observed brightness distributions in overcast skies

Lee

Devan

2008

Appl. Opt.

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Beneath most overcasts, clouds' motions and rapidly changing optical depths complicate mapping their angular distributions of luminance L v and visible-wavelength radiance L. Fisheye images of overcast skies taken with a radiometer-calibrated digital camera provide a useful new approach to solving this problem. Maps calculated from time-averaged images of individual overcasts not only show their brightness distributions in unprecedented detail, but they also help solve a long-standing puzzle about where brightness maxima of overcasts are actually located. When combined with simulated radiance distributions from MODTRAN4, our measured radiances also let us estimate the gradients of cloud thickness observed in some overcasts.

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“…Currently, their atmospheric models are based on MODTRAN4 [Anderson et al, 2000] and therefore do not include the important NLTE contributions of the upper atmosphere. In addition, both assume that the sky and earth radiance is isotropic.…”

Section: Space Object Modelsmentioning

confidence: 99%

Contributions of the OH Airglow to Resident Space Object Irradiance

Gruninger¹,

Duff²

2005

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MODTRAN4: radiative transfer modeling for remote sensing

Cited by 85 publications

References 0 publications

Gross Primary Production of a Wheat Canopy Relates Stronger to Far Red Than to Red Solar-Induced Chlorophyll Fluorescence

Gross Primary Production of a Wheat Canopy Relates Stronger to Far Red Than to Red Solar-Induced Chlorophyll Fluorescence

Observed brightness distributions in overcast skies

Contributions of the OH Airglow to Resident Space Object Irradiance

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