Global Atmospheric Models for Cosmic Ray Detectors

TL;DR

This paper discusses the implementation and validation of the GDAS atmospheric data system for cosmic ray air shower reconstruction, demonstrating its accuracy and potential for global application in various observatories.

Contribution

It introduces the use of GDAS data in cosmic ray detection, validating its accuracy against local measurements and highlighting its applicability worldwide.

Findings

GDAS data improves air shower reconstruction accuracy.

Validation shows strong agreement with local meteorological data.

GDAS can be effectively used in global cosmic ray observatories.

Abstract

The knowledge of atmospheric parameters -- such as temperature, pressure, and humidity -- is very important for a proper reconstruction of air showers, especially with the fluorescence technique. The Global Data Assimilation System (GDAS) provides altitude-dependent profiles of these state variables of the atmosphere and several more. Every three hours, a new data set on 23 constant pressure level plus an additional surface values is available for the entire globe. These GDAS data are now used in the standard air shower reconstruction of the Pierre Auger Observatory. The validity of the data was verified by comparisons with monthly models that were averaged from on-site meteorological radio soundings and weather station measurements obtained at the Observatory in Malarg\"ue. Comparisons of reconstructions using the GDAS data and the monthly models are also presented. Since GDAS is a global model, the data can potentially be used for other cosmic and gamma ray detectors. Several studies were already performed or are underway for several locations worldwide. As an example, a study performed in Colorado as part of an Atmospheric R&D for a possible future cosmic ray observatory is presented.