Approaches for hyperspectral remote flux quantification andvisualization of GHGs in the environment

• Methane (CH4) and nitrous oxide (N2O) are two very potent greenhouse gases, with highly heterogeneous distributionsin both space and time. Mapping hot-spots and source areas, and measuring fluxes in different environmentshas so far not been possible on a local scale using direct measurements. We have developed amethod for simultaneous mapping of methane (CH4) and nitrous oxide (N2O), also including water vapor(H2O), using ground-based remote sensing on a landscape-sized scale by utilizing Imaging Fourier TransformSpectrometers (IFTS) with high spectral resolution and imaging rates. The approach uses calculated libraries oftransmission spectra at the spectroscopic resolutions of the IFTS, based on the HITRAN database of spectroscopiclines and our own line-by-line radiative transfer model (LBLRTM). For each species, 1024 spectra have beenmade, resulting in 10243 combinations of column densities. Using an adaptive grid, solutions are found foreach line of sight at a spectral resolution of up to 0.25 cm−1 using the full spectral region of the detector. Themodeling ismulti-layered, calculating temperatures of the background, air, and any additional gas layers, also accountingfor reflected cold sky. Background distances can bemapped fromthe amount of water vapor in each lineof sight. The described approach can be used to identify sources, quantify gas distributions, and to calculate fluxes.Visualizations can produce gas distribution images, as well as air motion videos, which are used to map fluxesusing the same data set, without the need for additional instruments for wind measurements.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Hyperspectral

Thermal IR

Imaging Fourier Transform Spectrometer

Greenhouse gases

Methane

Nitrous oxide

Spectroscopic modeling

Radiative transfer

Landscape scale

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