Estimate of Radiosonde Dry Bias From Far‐Infrared Measurements on the Antarctic Plateau

2018 ◽  
Vol 123 (6) ◽  
pp. 3205-3211 ◽  
Author(s):  
R. Rizzi ◽  
T. Maestri ◽  
C. Arosio
Keyword(s):  
Far Infrared ◽  
Antarctic Plateau ◽  
Infrared Measurements ◽  
The Antarctic ◽  
Dry Bias

scholarly journals Astronomy from Antarctica

2005 ◽  
Vol 17 (4) ◽  
pp. 555-560 ◽  
Author(s):  
J.W.V. STOREY
Keyword(s):  
Absolute Humidity ◽  
Far Infrared ◽  
Antarctic Plateau ◽  
Earth Like Planets ◽  
Remote Sites ◽  
Large Telescopes ◽  
New Generation ◽  
The Antarctic ◽  
City Centres ◽  
Optical Telescopes

Astronomers have always sought the very best locations for their telescopes. From observatories in city centres, astronomers moved first to nearby mountain tops, then to remote sites in distant countries, to aircraft, and into space. In the past decade we have come to realize that the best astronomical observing conditions on the surface of the earth are to be found on the Antarctic plateau. The combination of high altitude, low temperature, low absolute humidity, low wind and extremely stable atmosphere offers astronomers gains in sensitivity and measurement precision that can exceed two orders of magnitude over even the best temperate sites. In addition, spectral windows are opened up – particularly in the far-infrared and terahertz regions – that are otherwise only accessible from high-flying aircraft or from space. Established and highly successful telescopes at the South Pole are soon to be joined by a new generation of facilities at Concordia Station, including large telescopes and interferometers. It has even been suggested that the largest optical telescopes currently proposed, with diameters of up to 100 m, might achieve their science goals at a lower overall cost if they are built on the Antarctic plateau rather than at a temperate site. Such telescopes offer the possibility of not only detecting earth-like planets in other star systems, but also of analysing their atmospheres spectroscopically.

scholarly journals Ice and mixed-phase cloud statistics on the Antarctic Plateau

2021 ◽  
Vol 21 (18) ◽  
pp. 13811-13833
Author(s):  
William Cossich ◽  
Tiziano Maestri ◽  
Davide Magurno ◽  
Michele Martinazzo ◽  
Gianluca Di Natale ◽  
...  
Keyword(s):  
Far Infrared ◽  
Mixed Phase ◽  
High Spectral Resolution ◽  
Ice Clouds ◽  
Antarctic Plateau ◽  
Clear Sky ◽  
The Mean ◽  
Sky Conditions ◽  
Mixed Phase Clouds ◽  
The Antarctic

Abstract. Statistics on the occurrence of clear skies, ice clouds, and mixed-phase clouds over Concordia Station, in the Antarctic Plateau, are provided for multiple timescales and analyzed in relation to simultaneous meteorological parameters measured at the surface. Results are obtained by applying a machine learning cloud identification and classification (CIC) code to 4 years of measurements between 2012–2015 of downwelling high-spectral-resolution radiances, measured by the Radiation Explorer in the Far Infrared – Prototype for Applications and Development (REFIR-PAD) spectroradiometer. The CIC algorithm is optimized for Antarctic sky conditions and results in a total hit rate of almost 0.98, where 1.0 is a perfect score, for the identification of the clear-sky, ice cloud, and mixed-phase cloud classes. Scene truth is provided by lidar measurements that are concurrent with REFIR-PAD. The CIC approach demonstrates the key role of far-infrared spectral measurements for clear–cloud discrimination and for cloud phase classification. Mean annual occurrences are 72.3 %, 24.9 %, and 2.7 % for clear sky, ice clouds, and mixed-phase clouds, respectively, with an inter-annual variability of a few percent. The seasonal occurrence of clear sky shows a minimum in winter (66.8 %) and maxima (75 %–76 %) during intermediate seasons. In winter the mean surface temperature is about 9 ∘C colder in clear conditions than when ice clouds are present. Mixed-phase clouds are observed only in the warm season; in summer they amount to more than one-third of total observed clouds. Their occurrence is correlated with warmer surface temperatures. In the austral summer, the mean surface air temperature is about 5 ∘C warmer when clouds are present than in clear-sky conditions. This difference is larger during the night than in daylight hours, likely due to increased solar warming. Monthly mean results are compared to cloud occurrence and fraction derived from gridded (Level 3) satellite products from both passive and active sensors. The differences observed among the considered products and the CIC results are analyzed in terms of footprint sizes and sensors' sensitivities to cloud optical and geometrical features. The comparison highlights the ability of the CIC–REFIR-PAD synergy to identify multiple cloud conditions and study their variability at different timescales.

scholarly journals Ice and Mixed-Phase Cloud Statistics on Antarctic Plateau

2021 ◽  
Author(s):  
William Cossich ◽  
Tiziano Maestri ◽  
Davide Magurno ◽  
Michele Martinazzo ◽  
Gianluca Di Natale ◽  
...  
Keyword(s):  
Time Scales ◽  
Far Infrared ◽  
Mixed Phase ◽  
Ice Clouds ◽  
Antarctic Plateau ◽  
Clear Sky ◽  
The Mean ◽  
Sky Conditions ◽  
Mixed Phase Clouds ◽  
The Antarctic

Abstract. Statistics on the occurrence of clear skies, ice and mixed-phase clouds over the Concordia station, in the Antarctic Plateau, are provided for multiple time scales and analysed in relation to simultaneous meteorological parameters measured at the surface. Results are obtained by applying a machine learning cloud identification and classification code (named CIC) to 4 years of measurements between 2012–2105 of down-welling high spectral resolution radiances, measured by the Radiation Explorer in the Far Infrared-Prototype for Applications and Development (REFIR-PAD) spectroradiometer. The CIC algorithm is optimized for Antarctic sky conditions (clear sky, ice clouds, and mixed-phase clouds) and results in a total hit rate of almost 0.98, where 1.0 is a perfect score. Scene truth is provided by LiDAR measurements that are concurrent with REFIR-PAD. The CIC approach demonstrates the key role of far infrared spectral measurements for clear/cloud discrimination and for cloud phase classification. Mean annual occurrences are 72.3 %, 24.9 % and 2.7 % for clear sky, ice and mixed-phase clouds respectively, with an inter-annual variability of a few percent. The seasonal occurrence of clear sky shows a minimum in winter (66.8 %) and maxima (75–76 %) during intermediate seasons. In winter the mean surface temperature is about 9 °C colder in clear conditions than when ice clouds are present. Mixed-phase clouds are observed only in the warm season; in summer they amount to more than one third of total observed clouds. Their occurrence is correlated with warmer surface temperatures. In the austral summer, the mean surface air temperature is about 5 °C warmer when clouds are present than in clear sky conditions. This difference is larger during the night than in daylight hours, likely due to increased solar warming. A comparison of monthly mean results with cloud occurrence/fraction derived from gridded (Level-3) satellite products, from both passive and active sensors, emphasizes the difficulty of adequately inferring cloud/clear-sky properties in the Antarctic region and highlights the ability of the CIC/REFIR-PAD synergy to identify multiple cloud conditions and study their variability at different time scales.

Far-infrared measurements of Holstein processes and low-energyαtr2F(ω)structure inV3Si

1979 ◽  
Vol 19 (11) ◽  
pp. 5689-5693 ◽  
Author(s):  
S. W. McKnight ◽  
S. Perkowitz ◽  
D. B. Tanner ◽  
L. R. Testardi
Keyword(s):  
Far Infrared ◽  
Infrared Measurements

Astronomy on Ice

1986 ◽  
Vol 6 (4) ◽  
pp. 403-415 ◽  
Author(s):  
Martin A. Pomerantz
Keyword(s):  
Gamma Ray ◽  
Far Infrared ◽  
The United States ◽  
High Energy ◽  
Observational Cosmology ◽  
Significant Information ◽  
Infrared Measurements ◽  
Energy Gamma ◽  
Low Humidity ◽  
Scientific Station

AbstractThe geographic South Pole, where the United States maintains a year-round scientific station, affords a number of unique advantages for certain types of astronomical observations. These include: continuous viewing and constant declination of ail objects in the southern celestial hemisphere, exceedingly low humidity, extended periods of coronal seeing, high altitude, and uniform terrain. The areas of research that have already benefited immensely from thèse extraordinary features are helioseismology and submillimeter astronomy. Unparalleled observations of global solar oscillations have already yielded significant information about the structure and dynamics of the Sun’s interior. Far infrared measurements of various galactic and extra-galactic regions have attained an unprecedented level of sensitivity, limited for the first time only by the noise inherent in the detector. In addition to further helioseismological observations, currently planned future activities include observational cosmology and ultra high energy gamma ray astronomy.

scholarly journals Determination of confusion noise for far-infrared measurements

2005 ◽  
Vol 430 (1) ◽  
pp. 343-353 ◽  
Author(s):  
Cs. Kiss ◽  
U. Klaas ◽  
D. Lemke
Keyword(s):  
Far Infrared ◽  
Infrared Measurements

scholarly journals The growth of sublimation crystals and surface hoar on the Antarctic plateau

2014 ◽  
Vol 8 (4) ◽  
pp. 1205-1215 ◽  
Author(s):  
J.-C. Gallet ◽  
F. Domine ◽  
J. Savarino ◽  
M. Dumont ◽  
E. Brun
Keyword(s):  
Energy Budget ◽  
Temperature Drop ◽  
Snow Surface ◽  
Surface Mass ◽  
Antarctic Plateau ◽  
Time Variations ◽  
Sunny Weather ◽  
Frost Flowers ◽  
Snow Model ◽  
The Antarctic

Abstract. On the Antarctic plateau, precipitation quantities are so low that the surface mass budget is for an important part determined by exchanges of water vapor between the snow surface and the atmosphere surface. At Dome C (75° S, 123° E), we have frequently observed the growth of crystals on the snow surface under calm sunny weather. Here we present the time variations of specific surface area (SSA) and density of these crystals. Using the detailed snow model Crocus, we conclude that the formation of these crystals was very likely due to the nighttime formation of surface hoar crystals and to the daytime formation of sublimation crystals. These latter crystals form by processes similar to those involved in the formation of frost flowers on young sea ice. The formation of these crystals impacts the albedo, mass and energy budget of the Antarctic plateau. In particular, the SSA variations of the surface layer can induce an instantaneous forcing at the snow surface up to −10 W m−2 at noon, resulting in a surface temperature drop of 0.45 K. This result confirms that snow SSA is a crucial variable to consider in the energy budget and climate of snow-covered surfaces.

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