@article{fdi:010070841,
  title = {{R}eassessment of the temperature-emissivity separation from multispectral thermal infrared data : introducing the impact of vegetation canopy by simulating the cavity effect with the {SAIL}-{T}hermique model},
  author = {{J}acob, {F}r{\'e}d{\'e}ric and {L}esaignoux, {A}. and {O}lioso, {A}. and {W}eiss, {M}. and {C}aillault, {K}. and {J}acquemoud, {S}. and {N}erry, {F}. and {F}rench, {A}. and {S}chmugge, {T}. and {B}riottet, {X}. and {L}agouarde, {J}. {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e investigated the use of multispectral thermal imagery to retrieve land surface emissivity and temperature. {C}onversely to concurrent methods, the temperature emissivity separation ({TES}) method simply requires single overpass without any ancillary information. {T}his is possible since {TES} makes use of an empirical relationship that estimates the minimum emissivity epsilon-min from the emissivity spectral contrast captured over several channels, so-called maximum-minimum difference ({MMD}). {I}n previous studies, the epsilon-min-{MMD} empirical relationship of {TES} was calibrated and validated for various sensor spectral configurations, where the proposed calibrations involved single or linearly mixed spectra of emissivity at the leaf or soil level. {H}owever, cavity effect should be taken into account at the vegetation canopy level, to avoid an underestimation of emissivity, especially for intermediate vegetation conditions between bare soil and full vegetation cover. {T}he current study aimed to evaluate the performances of the {TES} method when applied to vegetation canopies with cavity effect. {W}e used the {SAIL}-{T}hermique model to simulate a library of emissivity spectra for a wide range of soil and plant conditions, and we addressed the spectral configurations of recent and forthcoming sensors. {W}e obtained good results for calibration and validation over the simulated library, except for full cover canopies because of the {TES} gray body problem. {C}onsistent with previous studies, the calibration/validation results were better with more channels that capture emissivity spectral contrast more efficiently. {O}ur {TES} calibrations provided larger epsilon-min values as compared to former studies, especially for intermediate vegetation cover. {W}e explained this trend by the simulated spectral library that involved numerous vegetation canopies with cavity effect, thereby shifting up the epsilon-min-{MMD} empirical relationship. {C}onsequently, our {TES} calibration provided larger (respectively lower) estimates of emissivity (respectively radiometric temperature) that were likely to be more realistic as compared to previous calibrations. {F}inally, {SAIL}-{T}hermique simulations permitted to show that increasing {L}eaf {A}rea {I}ndex induced a displacement of the (epsilon-min, {MMD}) pairs along the empirical relationship. {T}his was consistent with the {TES} underlying assumption, where any change in epsilon-min induces changes in {MMD} since epsilon-max is bounded on [0.98-1]. {F}urther investigations should focus on validating the outcomes of the current study against ground-based measurements, and on assessing {TES} performances when accounting for instrumental and atmospheric perturbations.},
  keywords = {{T}hermal infrared remote sensing ; {T}emperature/emissivity separation ; {M}ultispectral observations ; {SAIL}-{T}hermique radiative transfer model ; {V}egetation canopy ; {C}avity effect},
  booktitle = {},
  journal = {{R}emote {S}ensing of {E}nvironment},
  volume = {198},
  numero = {},
  pages = {160--172},
  ISSN = {0034-4257},
  year = {2017},
  DOI = {10.1016/j.rse.2017.06.006},
  URL = {https://www.documentation.ird.fr/hor/fdi:010070841},
}