## 2 Technical Analysis and Data Selection  
For the ionization induced by cosmic rays, the CRAC:CRII model of the Oulu University was used--a numerical model that computes the CRII from the sea level to up to 40 km in the atmosphere, for every location on Earth. This model uses the Monte Carlo CORSIKA tool (v.6.617 August 2007) [41], which provides a full development simulation of an electromagnetic-muon-nucleonic cascade in the atmosphere, as well as the FLUKA package for the low-energy interactions (v.2006.3b March 2007) [42] and is fully described in [12; 13].  
Moreover, concerning calculations of the CRII for specific latitudes, altitudes and time periods, considering both solar and galactic cosmic rays, the \"Cosmic Ray Induced Ionization: Do-it-yourself kit\" ([[http://cosmicrays.oulu.fi/CRII/CRII.html](http://cosmicrays.oulu.fi/CRII/CRII.html)]([http://cosmicrays.oulu.fi/CRII/CRII.html](http://cosmicrays.oulu.fi/CRII/CRII.html))) (accessed on 5 May 2022) of the Oulu Cosmic Ray Station was used, and the monthly and annual values of the modulation parameter Phi (in MV), reconstructed from the ground-based cosmic ray data, are provided [43; 44]. The modulation parameter corresponds to the local interstellar spectrum (LIS) of cosmic rays, as provided by [45].  
In order to calculate the ambient dose equivalent rate dH*(10)/dt, DYNASTIMA was used [39]. Monte Carlo simulations of the secondary cascades taking place in the different atmospheric layers were performed with this independent GEANT4 software tool [46; 47; 48], which allowed for the determination of several characteristics of the cascade, such as the energy of the particles and the energy deposits at the different atmospheric layers. The FTFP_BERT_HP GEANT4 physics list was used, as it adequately describes all processes taking place due to secondary cascades. Then, several radiobiological quantities were calculated with the DYNASTIMA-R extension. Specifically, the operational quantity dH*(10)/dt was estimated by taking into consideration the different radiation weighting factors that corresponded to the different types of secondary cosmic ray particles [9]. DYNASTIMA/DYASTIMA-R is a validated tool [40; 49; 50], as it meets the criteria provided by the ICRU and ICRP documents [18; 19] regarding radiation protection in the aviation sector. DYNASTIMA software was provided through the portal of the Athens Neutron Monitor Station (A.Ne.Mo.S.) ([[http://cosray.phys.uoa.gr/index.php/dyastima](http://cosray.phys.uoa.gr/index.php/dyastima)]([http://cosray.phys.uoa.gr/index.php/dyastima](http://cosray.phys.uoa.gr/index.php/dyastima))) (accessed on 6 April 2022), while a database of selected simulated scenarios is available as a federated product on the ESA SWE Portal ([[https://swe.ssa.esa.int/dyastima-federated](https://swe.ssa.esa.int/dyastima-federated)]([https://swe.ssa.esa.int/dyastima-federated](https://swe.ssa.esa.int/dyastima-federated))) (accessed on 6 April 2022).  
The required input parameters for performing a simulation with DYNASTIMA concern the characteristics of the planet and its atmosphere, as well as the differential spectrum of the incoming primary cosmic ray particles at the top of the atmosphere. As far as the simulations presented in this work are concerned, the atmospheric profile was based on the International Standard Atmosphere (ISA) model [51], while the ISO15390 model was used for the determination of the primary cosmic ray spectra [52]. To take into account the effect of the geomagnetic field, maps of the cut-off rigidity threshold values as a function of the geographic coordinates were used, based on the International Geomagnetic Reference Field (IGRF) [53; 54; 55; 56]. The magnetic field components were obtained via the National Oceanic and Atmospheric Administration portal ([[https://www.ngdc.noaa.gov/geomag/](https://www.ngdc.noaa.gov/geomag/)]([https://www.ngdc.noaa.gov/geomag/](https://www.ngdc.noaa.gov/geomag/))) (accessed on 24 March 2022).