TAPAS is a free online service for the astronomical community, allowing the user to access simulated atmospheric transmission for specific observing conditions (description available in Bertaux et al., 2014). It is accessible through the AERIS database using :
- the latest available version of the HITRAN spectroscopic database
- the most realistic atmospheric profile (temperature T(z) and pressure p(z) ) available in the ECMWF meteorological field adapted to the location and time of the observation, with the addition of an estimate of MSIS-E for altitudes above 1 hPa pressure. The composite profiles (p,T, density) are produced by an AERIS product called Arletty.
For future observations, a climatological atmospheric profile is calculated – the LBLRTM software for the calculation of atmospheric transmittance in spherical geometry including refraction – The user receives an email with a link to where the required atmospheric transmittance product is located. The user can then filter their observed spectrum through the simulated transmission spectrum to obtain the target “out of atmosphere” spectrum.
The TAPAS service allows you to:
- Make use of AERIS services to interpolate via ECMWF (European Centre for Medium-Range Weather Forecasts) the pressure, temperature and profile of the species concerned at the location of your observation site and within 6 hours of the date of your observations.
- Calculate the atmospheric transmittance from the top of the atmosphere to the observatory, based on the high-resolution transmission molecular absorption database (HITRAN) and the Line-By-Line Radiative Transfer Model (LBLTRM) code.
- Provide separate transmittances associated with H2O, O2, O3, CO2, CH4, NO2 and Rayleigh scattering.
- To highlight other atmospheric features through your astronomical spectrum.
The ESPRI/AERIS teams have recently made available the new TAPAS web interface following a technology migration within the AERIS ecosystem. New molecules and parameters will be available in the new version.