Probing the Atmospheric Precipitable Water Vapor with SOFIA, Part I, Measurements of the Water Vapor Overburden with FIFI-LS

Fischer, Christian; Iserlohe, C.; Vacca, W.; Fadda, D.; Colditz, Sebastian; Fischer, Nicolas; Krabbe, A.

doi:10.1088/1538-3873/abf1ca

Cited by 11 publications

(11 citation statements)

References 13 publications

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“…Since the [O I]63 μm and the CO(14 → 13) lines are on the wings of broad telluric water absorption features and the spectra have strong continua, we were able to fit the atmospheric model to the spectra by letting PWV be a free parameter. We obtained values between 2 and 3 μm of PWV for these flights, which are consistent with those derived from satellite data (Iserlohe et al 2021) for the 2016 data as well as the FIFI-LS measurements taken directly before and after the data acquisition in 2019 (Fischer et al 2021). Thus we used 2.5 μm PWV for all observations.…”

Section: Data Reductionsupporting

confidence: 87%

The Photodissociation and Ionization Fronts in M17-SW Localized with FIFI-LS on Board SOFIA

Klein

Reedy

Fischer

et al. 2023

ApJ

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To understand star formation rates, studying feedback mechanisms that regulate star formation is necessary. The radiation emitted by nascent massive stars play a significant role in feedback by photodissociating and ionizing their parental molecular clouds. To gain a detailed picture of the physical processes, we mapped the photodissociation region (PDR) M17-SW in several fine-structure and high-J CO lines with FIFI-LS, the far-infrared imaging spectrometer aboard SOFIA. An analysis of the CO and [O i]146 μm line intensities, combined with the far-infrared intensity, allows us to create a density and UV intensity map using a one-dimensional model. The density map reveals a sudden change in the gas density crossing the PDR. The strengths and limits of the model and the locations of the ionization and photodissociation front of the edge-on PDR are discussed.

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Section: Data Reductionsupporting

confidence: 87%

The Photodissociation and Ionization Fronts in M17-SW Localized with FIFI-LS on Board SOFIA

Klein

Reedy

Fischer

et al. 2023

ApJ

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“…Since the [O I]63 µm and the CO(14 → 13) lines are on the wings of broad telluric water absorption features and the spectra have strong continua, we were able to fit the atmospheric model to the spectra by letting PWV as a free parameter. We obtained values between 2 and 3 µm of PWV for these flights which are consistent with those derived from satellite data (Iserlohe et al 2021) for the 2016 data as well as the FIFI-LS measurements taken directly before and after the data acquisition in 2019 (Fischer et al 2021). Thus we used 2.5 µm PWV for all observations.…”

Section: Data Reductionsupporting

confidence: 86%

The PDR fronts in M17-SW localized with FIFI-LS onboard SOFIA

Klein¹,

Reedy²,

Fischer³

et al. 2023

Preprint

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To understand star formation rates, studying feedback mechanisms that regulate star formation is necessary. The radiation emitted by nascent massive stars play a significant role in feedback by photodissociating and ionizing their parental molecular clouds. To gain a detailed picture of the physical processes, we mapped the photo-dissociation region (PDR) M17-SW in several fine structure and high-J CO lines with FIFI-LS, the far-infrared spectrometer aboard SOFIA. An analysis of the CO and [O I]146µm line intensities, combined with the far infrared intensity, allows us to create a density and UV intensity map using a one dimensional model. The density map reveals a sudden change in the gas density crossing the PDR. The strengths and limits of the model and the locations of the ionization and photo-dissociation front of the edge-on PDR are discussed.

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“…In order to test the PWV determination procedure implemented in the pipeline, it is useful to compare the derived FORCAST PWV values with those obtained from the dataset generated by the ECMWF's fifth European Re-analysis (ERA5) (Hersbach et al 2020). Briefly, the ERA5 combines observational data from satellites, aircraft, and in situ surface stations across the globe with models to generate a globally complete and internally consistent set of atmospheric parameters on a regular longitude-latitude grid with a spatial resolution of 31 km, over 37 pressure levels ranging from 1 mbar to 1000 mbar, at a time resolution of one hour every day from 1950 onwards.…”

Section: Comparison With Era5-ecmwf Pwv Valuesmentioning

confidence: 99%

“…This paper is the fourth in a series in which we discuss novel atmospheric calibration efforts for data acquired with the instruments on board SOFIA. In paper I (Fischer et al 2021) we discussed in detail the method for determining the atmospheric absorption in spectra obtained with the Field Imaging Far-Infrared Line Spectrometer (FIFI-LS) using in situ PWV measurements estimated from FIFI-LS observations designed to target specific water features. In paper II (Iserlohe et al 2021), we presented a comparison between the estimates of PWV derived from the direct FIFI-LS observations of water vapor emission features measured in-flight and the PWV values obtained from the ERA5-ECMWF data set.…”

Section: Introductionmentioning

confidence: 99%

Probing the Atmospheric Precipitable Water Vapor with SOFIA, Part. IV. Water Vapor Estimates from FORCAST Grism Spectra

Vacca¹,

Iserlohe²,

Shenoy³

et al. 2023

PASP

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SOFIA was an airborne observatory for far-infrared astronomy stationed at the Armstrong Flight Research Center in Palmdale, CA, USA. Although SOFIA flew at altitudes of ∼41,000 ft, any far-infrared observations from within the Earth’s atmosphere are nevertheless hampered by water vapor absorbing the astronomical signal. The primary atmospheric parameter governing absorption at far-infrared wavelengths is the total upward precipitable water vapor (PWV). In this paper we present a method of deriving PWV values directly from low resolution (R ∼ 100–200) mid-infrared (5–40 μm) spectroscopic observations and apply it to low resolution grism spectra obtained with the FORCAST instrument on-board SOFIA. We then compare these values with those determined from the fifth European Re-analysis (ERA5) of the global atmospheric parameters provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) for the time and altitude corresponding to the SOFIA observations. In general, we find a very good correlation between the ERA5-ECMWF values and the values derived from the FORCAST grism spectra, especially for high signal-to-noise ratio data. These results indicate that ERA5-ECMWF PWV values can be used to generate the telluric corrections for FORCAST imaging data as well as grism spectra for which the PWV values cannot be determined directly. We also derive the resolving power of the various grism and slit width combinations for FORCAST. Our results will be useful for reprocessing the FORCAST data in the SOFIA archive.

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Probing the Atmospheric Precipitable Water Vapor with SOFIA, Part I, Measurements of the Water Vapor Overburden with FIFI-LS

Cited by 11 publications

References 13 publications

The Photodissociation and Ionization Fronts in M17-SW Localized with FIFI-LS on Board SOFIA

The Photodissociation and Ionization Fronts in M17-SW Localized with FIFI-LS on Board SOFIA

The PDR fronts in M17-SW localized with FIFI-LS onboard SOFIA

Probing the Atmospheric Precipitable Water Vapor with SOFIA, Part. IV. Water Vapor Estimates from FORCAST Grism Spectra

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