Differences in published characteristics of GLE60 and their consequences on computed radiation dose rates along selected flight paths

The radiation dose rates at flight altitudes can increase by orders of magnitude for a short time during energetic solar cosmic ray events, so called ground level enhancements (GLEs). Especially at high latitudes and flight altitudes, solar energetic particles superposed on galactic cosmic rays may cause radiation that exceeds the maximum allowed dosage limit for the general public. Therefore the determination of the radiation dose rate during GLEs should be as reliable as possible. Radiation dose rates along flight paths are typically determined by computer models that are based on cosmic ray flux and anisotropy parameters derived from neutron monitor and/or satellite measurements. The characteristics of the GLE on 15 April 2001 (GLE60) were determined and published by various authors. In this work we compare these results and investigate the consequences on the computed radiation dose rates along selected flight paths. In addition, we compare the computed radiation dose rates with measurements that were made during GLE60 on board two transatlantic flights

Research at Jungfraujoch

The High Altitude Research Station at Jungfraujoch is widely recognised as an important research site. This is documented by the fact that Jungfraujoch was recently selected as one of the 24 Global Atmosphere Watch stations (GAW) within the framework of WMO activities. The GAW activities are in line with the International Global Observing Strategy (IGOS) on Integrated Global Atmospheric Chemistry Observation (IGACO). In addition, Jungfraujoch is an alpine site within the Network for the Detection of Atmospheric Composition Change (NDACC). Jungfraujoch is also a station within national networks such as the Swiss national network of air pollution observation (NABEL), which is part of the European Monitoring and Evaluation Program (EMEP), investigating particularly the large-scale dissemination of air pollutants within Europe. The station was opened in 1931. Therefore, an international conference to celebrate the 75th anniversary of the High Altitude Research Station Jungfraujoch was held at Interlaken, Switzerland (11–13 September, 2006). Studies across different research fields were presented, stimulating discussions among representatives of many disciplines from chemists, physicists, astronomers, and biologists to physicians

What are the causes for the spread of GLE parameters deduced from NM data?

Investigations have shown that the analysis results of ground level enhancements (GLEs) based on neutron monitor (NM) data for a selected event can differ considerably depending the procedure used. This may have significant consequences e.g. for the assessment of radiation doses at flight altitudes. The reasons for the spread of the GLE parameters deduced from NM data can be manifold and are at present unclear. They include differences in specific properties of the various analysis procedures (e.g. NM response functions, different ways in taking into account the dynamics of the Earth’s magnetospheric field), different characterisations of the solar particle flux near Earth as well as the specific selection of NM stations used for the analysis. In the present paper we quantitatively investigate this problem for a time interval during the maximum phase of the GLE on 13 December 2006. We present and discuss the changes in the resulting GLE parameters when using different NM response functions, different model representations of the Earth’s magnetospheric field as well as different assumptions for the solar particle spectrum and pitch angle distribution near Earth. The results of the study are expected to yield a basis for the reduction in the spread of the GLE parameters deduced from NM data