Top: two examples of the distribution of the water-vapour volume-mixing ratio as a function of altitude. The black solid line corresponds to a volume-mixing ratio of 0 ppmv up to 3.1 km (Paranal altitude is 2.6 km), while the red dashed line corresponds to a constant relative humidity until 3.1 km. The total amount of precipitable water vapour, 2 mm, is identical for both profiles. Bottom: sample of the corresponding transmission spectra at R = 100 000. The higher amount of water vapour in the lower atmospheric layers above the observatory leads to both deeper cores and stronger continuum absorption.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.