J/A+A/588/A32 Precipitable water vapour at Cerro Armazones (Lakicevic+, 2016)
Atmospheric conditions at Cerro Armazones derived from astronomical data.
Lakicevic M., Kimeswenger S., Noll S., Kausch W., Unterguggenberger S.,
Kerber F.
<Astron. Astrophys. 588, A32 (2016)>
=2016A&A...588A..32L 2016A&A...588A..32L (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Earth
Keywords: site testing - instrumentation: spectrographs -
techniques: spectroscopic - methods: observational -
atmospheric effects - methods: numerical
Abstract:
We studied the precipitable water vapour (PWV) content near Cerro
Armazones and discuss the potential use of our technique of modelling
the telluric absorption lines for the investigation of other molecular
layers. The site is designated for the European Extremely Large
Telescope (E-ELT) and the nearby planned site for the Cherenkov
Telescope Array (CTA).
Spectroscopic data from the Bochum Echelle Spectroscopic Observer
(BESO) instrument were investigated by using line-by-line radiative
transfer model (LBLRTM) radiative transfer models for the Earths
atmosphere with the telluric absorption correction tool molecfit. All
observations from the archive in the period from December 2008 to the
end of 2014 were investigated. The dataset completely covers the El
Nino event registered in the period 2009-2010. Models of the 3D Global
Data Assimilation System (GDAS) were used for further comparison.
Moreover, for those days with coincidence of data from a similar study
with VLT/X-shooter and microwave radiometer LHATPRO data at Cerro
Paranal, a direct comparison is presented.
This analysis shows that the site has systematically lower PWV values,
even after accounting for the decrease in PWV expected from the higher
altitude of the site with respect to Cerro Paranal, using the average
atmosphere found with radiosondes. We found that GDAS data are not a
suitable method for predicting of local atmospheric conditions - they
usually systematically overestimate the PWV values. Due to the large
sample, we were furthermore able to characterize the site with respect
to symmetry across the sky and variation with the years and within the
seasons. This kind of technique of studying the atmospheric conditions
is shown to be a promising step into a possible monitoring equipment
for CTA.
Description:
We present 5879 measurements of the precipitable water vapour (PWV)
over Observatory Cerro Armazones, performed with the software
MOLECFIT, using astronomical spectra from Bochum Echelle Spectroscopic
Observer (BESO) instrument. As well, we provide PWV data from the 3D
Global Data Assimilation System (GDAS) for this site and coordinates
of the observed star for each measurement. The data in the table are
given in the following order: Index, date, time, PWV_BESO, PWV_GDAS,
azimuth, altitude.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 5879 Precipitable water vapour (PWV) over Cerro Armazones
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Index Number of observation
7- 16 A10 "date" Date Date of observation
18- 25 A8 "h:m:s" Time Time of observation (UT)
28- 33 F6.3 mm PWVBESO Precipitable water vapour (PWV) from BESO data
36- 41 F6.3 mm PWVGDAS Precipitable water vapour (PWV) from GDAS model
43- 50 F8.4 deg Azimuth Azimuth
53- 59 F7.4 deg Altitude Altitude
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Acknowledgements:
Masa Lakicevic, mlakicevic(at)ucn.cl
(End) Masa Lakicevic [UCN, Antofagasta], Patricia Vannier [CDS] 04-Feb-2016