Measurement of the water vapour vertical profile and of the Earth's outgoing far infrared flux

Palchetti, Luca; Bianchini, Giovanni; Carli, B.; Cortesi, Ugo; Bianco, Samuele Del

doi:10.5194/acp-8-2885-2008

Cited by 34 publications

(20 citation statements)

References 33 publications

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“…These data were then employed to control the relative humidity (RH) of the atmosphere, allowing us to consider only artefact-free measurements performed by the OPC. Furthermore, humidity usually decreases with height (Baars et al, 2008;Palchetti et al, 2008;Velasco et al, 2008;Laakso et al, 2007;Stratmann et al, 2003), and during balloon launches the mixing height was characterized by a sharp decrease in the RH content. The mean RH decrease across the ML was 8.5±0.8%.…”

Section: Atmospheric Aerosol and Meteorological Profilesmentioning

confidence: 99%

Vertically-resolved particle size distribution within and above the mixing layer over the Milan metropolitan area

et al. 2010

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Abstract. Vertical aerosol profiles were directly measured over the city of Milan during three years (2005)(2006)(2007)(2008) of field campaigns. An optical particle counter, a portable meteorological station and a miniaturized cascade impactor were deployed on a tethered balloon. More than 300 vertical profiles were measured, both in winter and summer, mainly in conditions of clear, dry skies.The mixing height was determined from the observed vertical aerosol concentration gradient, and from potential temperature and relative humidity profiles. Results show that inter-consistent mixing heights can be retrieved highlighting good correlations between particle dispersion in the atmosphere and meteorological parameters. Mixing height growth speed was calculated for both winter and summer showing the low potential atmospheric dispersion in winter.Aerosol number size distribution and chemical composition profiles allowed us to investigate particle behaviour along height. Aerosol measurements showed changes in size distribution according to mixing height. Coarse particle profiles (d p >1.6 µm) were distributed differently than the fine ones (d p <1.6 µm) were, at different heights of the mixing layer. The sedimentation process influenced the coarse particle profiles, and led to a reduction in mean particle diameter for those particles observed by comparing data above the mixing height with ground data (−14.9±0.6% in winter and −10.7±1.0% in summer). Conversely, the mean particle diameter of fine particles increased above the mixing height under stable atmospheric conditions; the average inCorrespondence to: L. Ferrero (luca.ferrero@unimib.it) crease, observed by comparing data above the mixing height with ground data, was +2.1±0.1% in winter and +3.9±0.3% in summer. A hierarchical statistical model was created to describe the changes in the size distribution of fine particles along height. The proposed model can be used to estimate the typical vertical profile characterising launches within prespecified groups starting from: aerosol size and meteorological conditions measured at ground-level, and a mixing height estimation. The average increase of fine particle diameter, estimated on the basis of the model, was +1.9±0.5% in winter and +6.1±1.2% in summer, in keeping with experimental findings.

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Section: Atmospheric Aerosol and Meteorological Profilesmentioning

confidence: 99%

Vertically-resolved particle size distribution within and above the mixing layer over the Milan metropolitan area

et al. 2010

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“…The radiative impact of precipitating clouds raised the need to study the TICs in more detail (Jouan et al, 2012), and the F-IR proved to be a good candidate to observe those clouds (Blanchard, 2011) and discriminate between precipitating and non-precipitating ones (Yang, 2003;Blanchard et al, 2009). Such F-IR observations have already been used to study TIC at Eureka in the Arctic (Mariani et al, 2012) and at Dome C in Antarctica (Palchetti et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

Libois¹,

Proulx

Ivanescu³

et al. 2016

Atmos. Meas. Tech.

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Abstract. A far infrared radiometer (FIRR) dedicated to measuring radiation emitted by clear and cloudy atmospheres was developed in the framework of the Thin Ice Clouds in Far InfraRed Experiment (TICFIRE) technology demonstration satellite project. The FIRR detector is an array of 80 × 60 uncooled microbolometers coated with gold black to enhance the absorptivity and responsivity. A filter wheel is used to select atmospheric radiation in nine spectral bands ranging from 8 to 50 µm. Calibrated radiances are obtained using two well-calibrated blackbodies. Images are acquired at a frame rate of 120 Hz, and temporally averaged to reduce electronic noise. A complete measurement sequence takes about 120 s. With a field of view of 6°, the FIRR is not intended to be an imager. Hence spatial average is computed over 193 illuminated pixels to increase the signal-to-noise ratio and consequently the detector resolution. This results in an improvement by a factor of 5 compared to individual pixel measurements. Another threefold increase in resolution is obtained using 193 non-illuminated pixels to remove correlated electronic noise, leading an overall resolution of approximately 0.015 W m−2 sr−1. Laboratory measurements performed on well-known targets suggest an absolute accuracy close to 0.02 W m−2 sr−1, which ensures atmospheric radiance is retrieved with an accuracy better than 1 %. Preliminary in situ experiments performed from the ground in winter and in summer on clear and cloudy atmospheres are compared to radiative transfer simulations. They point out the FIRR ability to detect clouds and changes in relative humidity of a few percent in various atmospheric conditions, paving the way for the development of new algorithms dedicated to ice cloud characterization and water vapor retrieval.

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“…This has also been sparsely measured in the atmosphere for similar reasons to those of the submillimetre, despite representing up to half of the total outgoing longwave radiation and three quarters of the total incoming longwave radiation. Recent instruments designed to fill this gap include the Atmospheric Emitted Radiance Interferometer (AERI) (Turner et al, 2004), the Radiation Explorer in the Far InfraRed (REFIR) (Esposito et al, 2007;Palchetti et al, 2008), the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) Green et al (2012), the Interferometer for Basic Observation of Emitted Spectral Radiance of the Troposphere (I-BEST) Masiello et al (2012) and the Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument (Mlynczak et al, 2004). Whereas all of these instruments were designed to make consecutive measurements covering a wide spectral range, existing submillimetre instruments typically measure in narrow channels (excepting the SAO submillimetre FTS), in line with their primary purpose of detecting preselected lines of specific gases.…”

Section: Submillimetre Atmospheric Observationsmentioning

confidence: 99%

Simulation of submillimetre atmospheric spectra for characterising potential ground-based remote sensing observations

et al. 2016

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Abstract. The submillimetre is an understudied region of the Earth's atmospheric electromagnetic spectrum. Prior technological gaps and relatively high opacity due to the prevalence of rotational water vapour lines at these wavelengths have slowed progress from a ground-based remote sensing perspective; however, emerging superconducting detector technologies in the fields of astronomy offer the potential to address key atmospheric science challenges with new instrumental methods. A site study, with a focus on the polar regions, is performed to assess theoretical feasibility by simulating the downwelling (zenith angle = 0 • ) clearsky submillimetre spectrum from 30 mm (10 GHz) to 150 µm (2000 GHz) at six locations under annual mean, summer, winter, daytime, night-time and low-humidity conditions. Vertical profiles of temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr), hydrogen bromide (HBr), perhydroxyl radical (HO 2 ) and nitrous oxide (N 2 O) the emission lines producing the largest change in brightness temperature are identified. Signal strengths, centre frequencies, bandwidths, estimated minimum integration times and maximum receiver noise temperatures are determined for all cases. HOBr, HBr and HO 2 produce brightness temperature peaks in the mK to µK range, whereas the N 2 O peaks are in the K range. The optimal submillimetre remote sensing lines for the four species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad wavelength range. The techniques presented here provide a framework that can be applied to additional species of interest and taken forward to simulate retrievals and guide the design of future submillimetre instruments.

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Measurement of the water vapour vertical profile and of the Earth's outgoing far infrared flux

Cited by 34 publications

References 33 publications

Vertically-resolved particle size distribution within and above the mixing layer over the Milan metropolitan area

Vertically-resolved particle size distribution within and above the mixing layer over the Milan metropolitan area

A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

Simulation of submillimetre atmospheric spectra for characterising potential ground-based remote sensing observations

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