A simulation-based error budget of the TES method for the design of the spectral configuration of the micro-bolometer based MISTIGRI thermal infrared sensor

Authors: JACOB, FREDERIC - University Of Montpellier; VIDAL, THOMAS H.G. - Acri-St; LESAIGNOUX, AUDREY - University Of Montpellier; OLIOSO, ALBERT - Inrae; WEISS, MARIE - Inrae; NERRY, FRANCOISE - National Council For Scientific Research-Cnrs; JACQUEMOUD, STEPHANE - University Of Paris; GAMET, PHILIPPE - National Center For Space Studies; CAILLAULT, KARINE - Onera/dota; LABARRE, LUC - Onera/dota; French, Andrew; SCHMUGGE, THOMAS - New Mexico State University; BRIOTTET, XAVIER - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A; LAGOUARDE, JEAN-PIERRE - Inrae

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2021
Publication Date: 8/6/2021
Citation: Jacob, F., Vidal, T., Lesaignoux, A., Olioso, A., Weiss, M., Nerry, F., Jacquemoud, S., Gamet, P., Caillault, K., Labarre, L., French, A.N., Schmugge, T., Briottet, X., Lagouarde, J. 2021. A simulation-based error budget of the TES method for the design of the spectral configuration of the micro-bolometer based MISTIGRI thermal infrared sensor. IEEE Transactions on Geoscience and Remote Sensing. 60:1-19.

Interpretive Summary: Remote sensing of land surface temperature and emissivity is important for measuring surface energy fluxes, quantifying urban heat island effects, and ecosystem functioning of coastal zones. Sensors required to collect these measurements have to be precision-calibrated and accurate multispectral thermal imagers. Building, launching, and operating such sensors is a difficult and costly task, which means that instrumental design is critical. In preparation for an up-coming thermal infrared mission, TRISHNA, a study was conducted to answer design questions about the optimal number and positioning of the thermal bands. A simulation tool, SiMI, was created to answer these questions. The preparatory satellite mission 'MISTIGRI' and the temperature-emissivity separation algorithm 'TES' were used as a framework for the tool. SiMi considered atmospheric correction, instrumental noise, and model uncertainties. Results found that uncertainties due to atmospheric conditions and instrumental noise were equally important in determining land surface temperature and emissivity and that channel positioning was relatively unimportant. The study outlines a recommended 4-band configuration for the TRISHNA sensor. These findings are important for TRISHNA and for all scientists concerned with the design, construction, and application of multi-spectral thermal infrared remote sensing.

Technical Abstract: In preparation of the micro-bolometer based MIcro Satellite for Thermal Infrared GRound surface Imaging (MISTIGRI) mission, we study the error budget of the Temperature-Emissivity Separation (TES) method when used with several MISTIGRI spectral configurations that differ in channel number, locations, and widths. The error budget quantifies the contribution of (1) the TES underlying assumption about emissivity spectral contrast, (2) the errors on atmospheric corrections related to knowledge of atmospheric status at satellite overpass, and (3) the instrumental noise related to filter response functions for micro-bolometer sensing. To that end, we design an end-to-end simulator of MISTIGRI measurements (SiMi) in order to simulate the radiative and biophysical quantities involved in the data processing, from the measurement acquisition to the retrieval of variables of interest. We conduct numerous simulations over a wide range of realistic setups that notably include radiance trapping within vegetation canopy and subsequent cavity effect. When dealing with atmospheric corrections, we consider errors on atmospheric temperature and water vapor content, as well as on atmospheric concentrations of CO2 and O3. In the case of micro-bolometer based sensing, the current study highlights that the uncertainty on atmospheric corrections and the instrumental noise have similar impacts on the TES retrievals, with resulting errors twice as large as those due to the TES intrinsic assumption about spectral contrast, where the latter contributes to the TES error budget is within the [0.005 - 0.009] interval for emissivity, and within the [0.3 K - 0.4 K] interval for LST. Moreover, we show that retrieval performances of surface temperature are very similar across all considered MISTIGRI spectral configurations, with variation of RMSE within 0.2 K. Nonetheless, our study permits to select a spectral configuration with four channels as the most suited for the MISTIGRI instrument, notably because it enables a moderately better capture of the emissivity contrast than a 3-channel configuration.