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Setup for models

Continuum 

The following H2O line and continuum and dry air models for the samples presented here were used:

Frequency range 0 - 1000 GHz

The absorption due to water vapor is derived as described in Pardo et al. 2001. In addition, a pseudocontinuum water vapor absorption (quadratic term in frequency) stems from Fourier Transform Spectrometer (FTS) obervations in the 0-1 THz regime Pardo et al. (2005). The absorption due to dry air continuum consists of collisionally induced absorption (N2 and O2) that is also contained in the observationally based model of Pardo et al. (2001), and relaxation (Debye) absorption of O2 is considered using the formalism described in Rosenkranz (1993) and Pardo et al. (2001).


Frequency range 1000 - 2000 GHz

Based on FTS measurments in the 1-1.6 THz (Pardo et al. 2005), the authors showed that the quadratic frequency approximation for the H2O pseudocontinuum starts to fail for this frequency range and that the coefficent seems to be below 2 for f > 1.1 THz. We thus use the semi-empirical MT-CKD-2004 model , a continuation of the older CKD-model Clough et al. (1989). It includes continuum absorption due to water vapor, nitrogen, oxygen, CO2, and ozone. New is that the self and foreign continuum models are each based on the contributions from a collision induced component and a line shape component. These are applied to all water vapor lines from the millimetre regime to the visible, and the results summed to obtain self and foreign continuum coefficients from 0-20,000 cm-1. The high-frequency collision-induced spectrum of nitrogen is extracted from the formulation of Borysow and Frommhold (1986). The model is scaled with a factor 1.34 as suggested by Boissoles (2003).


Spectroscopic line parameters 

The spectroscopic parameters used in MOLIERE-5 are obtained from the VERDANI catalog Eriksson (1999) that contains the JPL and HITRAN data bases. The catalog is updated regularly and available athttp://www.chalmers.se/rss . We included all spectral lines in this catalog of molecules with a significant contribution (0.1 K brightness temperature) to the spectrum up to 3 THz. H2O lines are included up to 10 THz.


Temperature and pressure profiles 

Temperature (T) and pressure (p) profiles for each site are given seperately in the following compilation. All profiles are monthly averages and zonal means over 10 degrees; for example the site of ALMA at 23S was obtained averaging T,p-profile between 20 and 30 degrees South.


Vertical profiles of main and minor species 

Vertical profiles of the main absorbers (H2O,O3) and minor species are given in this compilation.


Other model parameters 

All models shown in this paper were calculated for 90 degrees elevation, i.e. zenith view and have a frequency resolution of 20-500 MHz (see individual figure captions).