Perturbations to astronomical observations at the European Southern Observatory’s very large telescope site in Paranal, Chile: analyses of climatological causes

Summary

¶A study has been conducted to assess the reasons for a significant decrease in the astronomic observing period since the Very Large Telescope of ESO (the European Southern Observatory) went into operation in 1998. Following a multi-year monitoring of meteorological parameters at the site of the ESO telescope in Paranal (northern Chile), the optimal climatic conditions observed there prior to the construction of the Very Large Telescope have not been as frequently recorded since.

In order to determine whether this region is being subjected to long-term changes in climate consecutive to 20^th century global warming, or whether the ENSO (El Niño/Southern Oscillation) event in the final years of the 1990s are responsible for this situation, climatological data from in situ measurements, upper-air soundings, analogical reconstructions of meteorological data to extend the records further back into the past, and large-scale re-analysis data have been used. The results point towards a dominant role of ENSO in the current problems that astronomers face with reduced observation time.