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The measurement of the Earth’s atmospheric emission spectrum is fundamental for the study of the global radiation budget. Up to now, this measurement has typically been limited to the mid-infrared region because of the technological limitations of space-borne spectrometers operating in the far infrared (FIR). The uncovered region of the FIR is however very important because most of the radiative cooling of the atmosphere, due to the strong rotational band of water vapor, occurs here. The REFIR-PAD (Radiation Explorer in the Far InfraRed—Prototype for Applications and Development) instrument is a completely uncooled Fourier transform spectrometer that allows to perform the spectrally resolved measurement of the entire atmospheric emission spectrum including the FIR region with a spectral resolution of 0.5 cm-1. REFIR-PAD was deployed in June 2005 on board a stratospheric balloon to perform the nadir-looking spectral measurement of the outgoing longwave radiation in the tropics, near Teresina (North-East Brazil), and in 2006–2007 in different ground-based campaigns in Italy to obtain zenith-looking spectral measurements of the downward longwave radiation from high-altitude. These wideband measurements have shown that the retrieval capability of atmospheric parameters is improved using the FIR portion of the emission spectrum. Moreover, both sets of measurements are important for the characterization of the spectroscopy of water vapor continuum in the relatively unexplored spectral region below 600 cm-1. [ABSTRACT FROM AUTHOR]

The spectral features of the downward longwave radiation have been characterized by exploiting spectral measurements, acquired over the Antarctic Plateau at Dome C at 3230 m, by the Radiation Explorer in the Far InfraRed - Prototype for Applications and Development (REFIR-PAD) spectroradiometer. REFIR-PAD is operative at the base with continuous operations over 24 hours since 2012 and measures the spectra from 100 to 1400 cm-1 with 0.4 cm-1 of resolution, covering the under-explored far-IR for the first time with systematic measurements. REFIR-PAD spectral measurements have been used to calculate the atmospheric longwave flux to be compared with standard measurements performed by BSRN, for validation and error estimates. The agreement is within the error estimate of 4.5Wm-2 for REFIR-PAD and 10Wm-2 for BRSN measurements. Finally, seasonal variabilities of the longwave flux measured in different spectral regions have been studied by exploiting 1-year dataset of measurements to show possible correlations with different atmospheric regimes. [ABSTRACT FROM AUTHOR]

The spectral features of the downward longwave radiation have been characterized by exploiting spectral measurements, acquired over the Antarctic Plateau at Dome C at 3230 m, by the Radiation Explorer in the Far InfraRed - Prototype for Applications and Development (REFIR-PAD) spectroradiometer. REFIR-PAD is operative at the base with continuous operations over 24 hours since 2012 and measures the spectra from 100 to 1400 cm-1 with 0.4 cm-1 of resolution, covering the under-explored far-IR for the first time with systematic measurements. REFIR-PAD spectral measurements have been used to calculate the atmospheric longwave flux to be compared with standard measurements performed by BSRN, for validation and error estimates. The agreement is within the error estimate of 4.5Wm-2 for REFIR-PAD and 10Wm-2 for BRSN measurements. Finally, seasonal variabilities of the longwave flux measured in different spectral regions have been studied by exploiting 1-year dataset of measurements to show possible correlations with different atmospheric regimes. [ABSTRACT FROM AUTHOR]

In this study we present an intercomparison of measurements of very low water vapor column content obtained with a Ground-Based Millimeter-wave Spectrometer (GBMS), Vaisala RS92k radiosondes, a Raman Lidar, and an IR Fourier Transform Spectrometer. These sets of measurements were carried out during the primary field campaign of the ECOWAR (Earth COoling by WAter vapor Radiation) project which took place on the Western Italian Alps from 3 to 16 March, 2007. [ABSTRACT FROM AUTHOR]