The Far Infrared FTS for the FORUM Mission

Palchetti, Luca; Olivieri, Monica; Pompei, C.; Labate, Demetrio; Brindley, Helen; Natale, Gianluca Di; Bianchini, Giovanni

doi:10.1364/fts.2016.ftu3c.1

Cited by 5 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A key test is whether the values retrieved from the upper level observations show consistency with the near-surface retrievals. The findings have direct relevance for two upcoming FIR satellite missions: National Aeronautics and Space Administration's (NASA's) Polar Radiant Energy in the Far Infrared Experiment (PREFIRE) and ESA's Far-Infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission (Palchetti et al, 2016(Palchetti et al, , 2020. Given that both aim to infer Arctic and, potentially, Antarctic surface emissivities in the FIR, the analyses performed here provide a useful indication of what can be achieved, taking into consideration the uncertainties in both the measured radiances and the atmospheric state.…”

Section: Introductionmentioning

confidence: 92%

Retrievals of High‐Latitude Surface Emissivity Across the Infrared From High‐Altitude Aircraft Flights

et al. 2020

View full text Add to dashboard Cite

We present retrievals of infrared spectral surface emissivities spanning the far infrared and mid-infrared from aircraft observations over Greenland, taken at an altitude of 9.2 km above sea level. We describe the flight campaign, available measurements, and the retrieval method. The principal barriers to reducing uncertainty in the emissivity retrievals are found to be instrumental noise and our ability to simultaneously retrieve the underlying surface temperature. However, our results indicate that using the instrumentation available to us it is possible to retrieve emissivities from altitude with an uncertainty of~0.02 or better across much of the infrared. They confirm that the far-infrared emissivity of snow and ice surfaces can depart substantially from unity, reaching values as low as 0.9 between 400 and 450 cm −1. They also show good consistency with retrievals from the same flight made from near-surface observations giving confidence in the methodology used and the results obtained for this more challenging viewing configuration. To the best of our knowledge, this is the first time that far-infrared surface emissivity has been retrieved from altitude and demonstrates that the methodology has the potential to be extended to planned satellite far-infrared missions.

show abstract

Section: Introductionmentioning

confidence: 92%

Retrievals of High‐Latitude Surface Emissivity Across the Infrared From High‐Altitude Aircraft Flights

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The Far-infrared Outgoing Radiation for Understanding and Monitoring (FORUM) (Palchetti et al, 2020(Palchetti et al, , 2016Ridolfi et al, 2020) and The Polar Radiant Energy in the Far Infrared Experiment (PREFIRE) (L'Ecuyer et al, 2021) are two satellite missions planned for launch in the near future. Both missions will provide, with different resolutions, spectral radiance measurements in the FIR and MIR regions of the terrestrial spectrum from space.…”

Section: Introductionmentioning

confidence: 99%

A new approach to the crystal habit retrieval from far infrared spectral radiance measurements

Di Natale,

Ridolfi,

Palchetti

2023

Preprint

View full text Add to dashboard Cite

Abstract. To generate reliable climate predictions, global models need accurate estimates of all the energy fluxes contributing to the Earth Radiation Budget (ERB). Clouds in general, and more specifically ice clouds play a key role in the determination of the ERB, as they may exert either a feedback or a forcing action, depending on their optical and microphysical properties and physical state (solid/liquid). To date, accurate statistics and climatologies of cloud parameters are not available. The ice cloud composition in terms of ice crystal shape (or habit) is one of the parameters with the largest uncertainty. This is because crystal shape estimates are generally hard to extract from space measurements. Satellite spectral radiance measurements available to date, are actually limited to the middle-infrared spectral region, therefore their information on ice cloud crystal habits is not sufficient to attempt a retrieval. The Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) experiment, foreseen to be the 9th Earth Explorer mission of the European Space Agency, will measure, for the first time spectrally resolved from space, the entire upwelling spectrum emitted by the Earth, from 100 to 1600 cm-1. The far-infrared portion of the Earth spectrum, especially from 200 to 600 cm-1, is very sensitive to cloud ice crystal shapes, thus FORUM measurements could also represent an opportunity to study the ice cloud composition in terms of ice crystal habit mixtures. To investigate this possibility, we developed an accurate and advanced scheme allowing to model ice cloud optical properties also in cases of clouds composed of mixed ice crystal habits. This feature is in fact necessary, because also in situ measurements acquired over the years point out that the shape of ice cloud crystals varies depending on the crystal size range. In our model, the resulting cloud optical properties are also determined by the input habit fractions. Thus, the retrieval of these fractions from spectral radiance measurements can be attempted. Using 375 different cloudy scenarios, we assess the performance of our retrieval scheme in the determination of crystal habit mixtures starting from FORUM simulated measurements. The most relevant error components affecting the retrieved cloud parameters are not very large and are of random nature, thus FORUM measurements will allow to set up an accurate climatology of cloud parameters. To provide an example of the benefit that one could get out of the habit mixture retrievals, we also show the improved accuracy of the thermal outgoing fluxes calculations as compared to using assumed mixtures.

show abstract

“…The requirements on the absolute accuracy are on the contrary much more stringent. ESA candidate mission, called Far-Infrared Outgoing Radiation Understanding and Monitoring (FORUM) (Palchetti et al, 2016) focuses on studying the forcings and the feedbacks of atmospheric water vapor and of ice clouds on the climate. The recently funded NASA Polar Radiant Energy in the Far-InfraRed Experiment (PREFIRE) CubeSat, to be launched in 2022, intends to measure in the 0 to 45-μm range to measure spatial and temporal variations in spectral fluxes on hourly to seasonal timescales (L'Ecuyer, 2019).…”

Section: Introductionmentioning

confidence: 99%

Optimal Configuration of a Far‐Infrared Radiometer to Study the Arctic Winter Atmosphere

et al. 2020

View full text Add to dashboard Cite

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

show abstract

The Far Infrared FTS for the FORUM Mission

Cited by 5 publications

References 3 publications

Retrievals of High‐Latitude Surface Emissivity Across the Infrared From High‐Altitude Aircraft Flights

Retrievals of High‐Latitude Surface Emissivity Across the Infrared From High‐Altitude Aircraft Flights

A new approach to the crystal habit retrieval from far infrared spectral radiance measurements

Optimal Configuration of a Far‐Infrared Radiometer to Study the Arctic Winter Atmosphere

Contact Info

Product

Resources

About