Analysis of the Ground Level Enhancement GLE 60 on 15 April 2001, and Its Space Weather Effects: Comparison With Dosimetric Measurements

• Published in: Space weather Vol. 21; no. 8
• Main Authors: Larsen, N., Mishev, A. L.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01.08.2023
• Subjects: Accuracy; Altitude; Aviation; Balloon measurements; Computation; Cosmic ray showers; Cosmic rays; dosimetric measurements; Dosimetry; Earth; Energetic particles; Flight; GLE 60; ground level enhancement; Modelling; Nowcasting; Particle physics; Radiation; Radiation damage; Radiation dosage; Solar activity; Solar cycle; Solar energetic particles; Solar protons; Space weather; Spacecraft; Weather effects
• ISSN: 1542-7390; 1539-4964; 1542-7390
• DOI: 10.1029/2023SW003488

As a result of notable solar activity observed in April 2001, one of the strongest ground level enhancements (GLE) of solar cycle 23 occurred, namely GLE # 60 on 15 April 2001. In this paper, we derived the spectral and angular characteristics, and apparent source position of the solar protons during the GLE # 60, using a verified by direct measurements model and employing the calibrated neutron monitor yield function. Subsequently, employing the updated and verified by balloon measurements dosimetric model: Oulu CRAC:DOMO (Cosmic Ray Atmospheric Cascade: Dosimetric Model) we computed the dose rates throughout the event at several altitudes using the obtained spectra as an input. A global map of the ambient dose at an altitude of 35 kft is computed. A comparison with direct dosimetric measurements obtained by a Liulin device during an intercontinental flight is performed and good agreement is achieved. Plain Language Summary During, and after, solar eruptions solar energetic particles (SEPs) can be produced. SEPs with enough energy, if directed at Earth, penetrate the Earth's magnetic environment and enter the atmosphere, upon which they create complex atmospheric cascades of secondary particles that are detected at the ground. These events are called ground level enhancements (GLEs). GLEs bring with them space weather risks caused by the increase in SEPs arriving at Earth, which can damage spacecraft and increase the radiation dose at aviation altitudes. Analyzing GLE events to determine their characteristics and space weather impacts is crucial for developing important space weather nowcasting capabilities that can help mitigate damage caused by future GLE events. This work presents the analysis of one such GLE event observed on 15 April 2001, this event is called GLE 60, also known as the Easter event. The spectral and angular characteristics of the SEPs during GLE 60 were derived and used to compute the radiation dose at aviation altitudes during the event using a new radiation model. The computed doses were then compared to direct dosimetric measurements obtained during an intercontinental flight that occurred during GLE 60 and a good agreement was obtained. Key Points Rigidity spectra and angular distribution of solar energetic protons during GLE 60 were derived Time profiles of the effective dose rates at several altitudes during GLE 60 and the global exposure map at 35 kft were computed Good agreement between the radiation model and measurements with Liulin dosimetric device from an intercontinental flight was achieved