Site testing for submillimetre astronomy at Dome C, Antarctica

Tremblin, Pascal; Minier, V.; Schneider, N.; Durand, Gilles; Ashley, M. C. B.; Lawrence, Jon; Luong-Van, D.; Storey, J. W. V.; Durand, Gilles; Reinert, Y.; Veyssière, C.; Walter, C. W.; Ade, Peter A. R.; Calisse, P. G.; Challita, Zalpha; Fossat, E.; Sabbatini, L.; Pellegrini, A.; Ricaud, Philippe; Urban, Joachim

doi:10.1051/0004-6361/201117345

Cited by 29 publications

(38 citation statements)

References 33 publications

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“…2) with the in-situ measurements (radio-soundings, HAMSTRAD, SUMMIT08). Possible explanations were discussed in Tremblin et al (2011) and should not be interpreted as a possible effect of the day-night variations. Figure 4 shows the comparison between all sites as a distribution function of the PWV over the period [2008][2009][2010].…”

Section: Iasi (Infrared Atmospheric Soundingmentioning

confidence: 99%

“…Based upon the method described in Tremblin et al (2011), we use MOLIERE to calculate the transmissions at 200 μm and 350 μm. We do not compute the transmissions for SOFIA here because it is by far superior to all ground-based sites.…”

Section: Site Comparisonmentioning

confidence: 99%

“…Schneider et al 2009;Tremblin et al 2011;Matsushita et al 1999;Peterson et al 2003) have already shown that a few sites are well-suited to submm/mid-IR, and FIR-astronomy and their transmission properties are rather well determined (for example by Fourier transform spectrometer obervations in the 0.5-1.6 THz range at Mauna Kea/Hawaii; Pardo et al 2001). The high-altitude (>5000 m) Chilean sites are known for dry conditions (see Matsushita et al 1999;Peterson et al 2003), and site testing is now being carried out at the driest place on Earth, Antarctica (see Chamberlin et al 1997;Yang et al 2010;Tremblin et al 2011). Comparisons between Antarctic and Chilean sites are difficult and uncertain since they rely on ground-based instruments that use different methods and calibration techniques (see Peterson et al 2003, for example).…”

Section: Introductionmentioning

confidence: 99%

“…A meaningful comparison is possible if several independent instruments are used at each place. An example of such a study is the one of Tremblin et al (2011) Article published by EDP Sciences A65, page 1 of 10 that obtained transmission data at Dome C thanks to radio soundings and the radiometers HAMSTRAD (Ricaud et al 2010) and SUMMIT08. However, it is rare to have many instruments at one site.…”

Section: Introductionmentioning

confidence: 99%

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Worldwide site comparison for submillimetre astronomy

Tremblin¹,

Schneider²,

Minier³

et al. 2012

A&A

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Aims. The most important limitation for ground-based submillimetre (submm) astronomy is the broad-band absorption of the total water vapour in the atmosphere above an observation site, often expressed as the precipitable water vapour (PWV). A long-term statistic on the PWV is thus mandatory to characterize the quality of an existing or potential site for observational submm-astronomy. In this study we present a three-year statistic (2008)(2009)(2010) of the PWV for ground-based telescope sites all around the world and for stratospheric altitudes relevant for SOFIA (Stratospheric Observatory for Far-Infrared Astronomy). The submm-transmission is calculated for typical PWVs using an atmospheric model. Methods. We used data from IASI (Infrared Atmospheric Sounding Interferometer) on the Metop-A satellite to retrieve water vapour profiles for each site (11 in total, comprising Antarctica, Chile, Mauna Kea, Greenland, Tibet). The use of a single instrument to make the comparison provides unbiased data with a common calibration method. The profiles are integrated above the mountain/stratospheric altitude to get an estimation of the PWV. We then applied the atmospheric model MOLIERE (Microwave Observation and LIne Estimation and REtrieval) to compute the corresponding atmospheric absorption for wavelengths between 150 μm and 3 mm. Results. We present the absolute PWV values for each site sorted by year and time percentage. The PWV corresponding to the first decile (10%) and the quartiles (25%, 50%, 75%) are calculated and transmission curves between 150 μm and 3 mm for these values are shown. The Antarctic and South-American sites present very good conditions for submillimetre astronomy. The 350 μm and 450 μm atmospheric windows are open all year long, whereas the 200 μm atmospheric window opens reasonably for 25% of the time in Antarctica and the extremely high-altitude sites in Chile. Potential interesting new facilities are Macon in Argentina and Summit in Greenland, which show similar conditions to for example, Mauna Kea (Hawaii). For SOFIA, we present transmission curves for different altitudes (11 to 14 km), PWV values, and higher frequencies (up to 5 THz) in more detail. Though the atmosphere at these altitude is generally very transparent, the absorption at very high frequencies becomes more important, partly caused by minor species. The method presented in this paper could identify sites on Earth, with great potential for submillimetre astronomy, and guide future site testing campaigns in situ.

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Section: Iasi (Infrared Atmospheric Soundingmentioning

confidence: 99%

Section: Site Comparisonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Worldwide site comparison for submillimetre astronomy

Tremblin¹,

Schneider²,

Minier³

et al. 2012

A&A

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“…The summer surface energy budget on the ice sheets is largely controlled by the absorption of solar energy by snow (Van As et al, 2005;Ettema et al, 2010). The latter is determined by the downward irradiance reaching the surface and by snow albedo.…”

Section: Introductionmentioning

confidence: 99%

Development and calibration of an automatic spectral albedometer to estimate near-surface snow SSA time series

et al. 2016

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Abstract. Spectral albedo of the snow surface in the visible/near-infrared range has been measured for 3 years by an automatic spectral radiometer installed at Dome C (75 • S, 123 • E) in Antarctica in order to retrieve the specific surface area (SSA) of superficial snow. This study focuses on the uncertainties of the SSA retrieval due to instrumental and data processing limitations. We find that when the solar zenith angle is high, the main source of uncertainties is the imperfect angular response of the light collectors. This imperfection introduces a small spurious wavelength-dependent trend in the albedo spectra which greatly affects the SSA retrieval. By modeling this effect, we show that for typical snow and illumination conditions encountered at Dome C, retrieving SSA with an accuracy better than 15 % (our target) requires the difference of response between 400 and 1100 nm to not exceed 2 %. Such a small difference can be achieved only by (i) a careful design of the collectors, (ii) an ad hoc correction of the spectra using the actual measured angular response of the collectors, and (iii) for solar zenith angles less than 75 • . The 3-year time series of retrieved SSA features a 3-fold decrease every summer which is significantly larger than the estimated uncertainties. This highlights the high dynamics of near-surface SSA at Dome C.

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Summer to Winter Diurnal Variabilities of Temperature and Water Vapour in the Lowermost Troposphere as Observed by HAMSTRAD over Dome C, Antarctica

Ricaud

Genthon

Durand

et al. 2011

Boundary-Layer Meteorol

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The HAMSTRAD (H 2 O Antarctica Microwave Stratospheric and Tropospheric Radiometers) microwave radiometer operating at 60 GHz (oxygen line, thus temperature) and 183 GHz (water vapour line) has been permanently deployed at the Dome C station, Concordia, Antarctica [75 • 06 S, 123 • 21 E, 3,233 m above mean sea level] in January 2010 to study long-term trends in tropospheric absolute humidity and temperature. The great sensitivity of the instrument in the lowermost troposphere helped to characterize the diurnal cycle of temperature and H 2 O from the austral summer (January 2010) to the winter (June 2010) seasons from heights of 10 to 200 m in the planetary boundary layer (PBL). The study has characterized the vertical resolution of the HAMSTRAD measurements: 10-20 m for 123 228 P. Ricaud et al.temperature and 25-50 m for H 2 O. A strong diurnal cycle in temperature and H 2 O (although noisier) has been measured in summertime at 10 m, decreasing in amplitude with height, and phase-shifted by about 4 h above 50 m with a strong H 2 O-temperature correlation (>0.8) throughout the entire PBL. In autumn, whilst the diurnal cycle in temperature and H 2 O is less intense, a 12-h phase shift is observed above 30 m. In wintertime, a weak diurnal signal measured between 10 to 200 m is attributed to the methodology employed, which consists of monthly averaged data, and that combines air masses from different origins (sampling effect) and not to the imprint of the null solar irradiation. In situ sensors scanning the entire 24-h period, radiosondes launched at 2000 local solar time (LST) and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at 0200, 0800, 1400 and 2000 LST agree very well with the HAMSTRAD diurnal cycles for temperature and relatively well for absolute humidity. For temperature, HAMSTRAD tends to be consistent with all the other datasets but shows a smoother vertical profile from 10 to 100 m compared to radiosondes and in-situ data, with ECMWF profiles even smoother than HAMSTRAD profiles, and particularly obvious when moving from summer to winter. For H 2 O, HAMSTRAD measures a much moister atmosphere compared to all the other datasets with a much weaker diurnal cycle at 10 m. Our study has helped characterize the time variation of the PBL at Dome C with a top around 200 m in summertime decreasing to 30 m in wintertime. In summer, from 2000 to 0600 LST a stable layer is observed, followed by a well-mixed layer the remaining time, while only a nocturnal stable layer remains in winter. In autumn, a daytime convective layer shallower than the nocturnal stable layer develops.

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Site testing for submillimetre astronomy at Dome C, Antarctica

Cited by 29 publications

References 33 publications

Worldwide site comparison for submillimetre astronomy

Worldwide site comparison for submillimetre astronomy

Development and calibration of an automatic spectral albedometer to estimate near-surface snow SSA time series

Summer to Winter Diurnal Variabilities of Temperature and Water Vapour in the Lowermost Troposphere as Observed by HAMSTRAD over Dome C, Antarctica

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