Precursory signals of Forbush decreases with and without shock wave

Many previous studies have shown that before the beginning of a Forbush Decrease (FD) of the cosmic ray intensity, a precursor signal can be observed. All these surveys were focused on FDs that are associated with a sudden storm com- mencement (SSC). In this work we demonstrate that precursors could also be observed in events without a SSC that is determined by an abrupt increase of the interplanetary magnetic field. The type of precursory signals and their diversity among the events are the main purpose of this study. We try to figure out similarities and differences on the signals and the associated events from both categories in the last fifty years, from 1969 to 2019, using the same selection criteria of the under investigation FDs. Simultaneously the orientation of the upcoming solar disturbances in comparison to the way they configure the increase of the interplanetary magnetic field and create these signals are discussed

Unusual decrease of the cosmic ray intensity in May 2019 on the background of the minima solar activity

In May 2019 there was a long and sloping decreasing of cosmic ray’s intensity (up to ~4%), which was observed on neutron monitors. Despite this was a small decreasing compared to quasi-eleven-period variation, it stands out well in 24th cycle of solar activity. According to LASCO/SOHO and STEREO-A data from spectrometer in different UHF bands and from coronograph, there was a series of CMEs which affected on modulation of cosmic rays by creating a series of Forbush decrea - sing, which didn’t restore. This series was connected to two active regions on sun and began on April 30 from “reversed halo” CME. This CME didn’t reach the earth, but led to significant additional modulation of cosmic rays, mostly on east side. Later there was a series of smaller CMEs on May 1-6, which also didn’t reach the earth, but were gradually approaching to Earth. Recent CMEs on 8-9 and 12-13 created a normal Forbush decreasing. In May 2019, cosmic rays shown again, that they can collect information about distant objects of geliosphere and transmit it to Earth. The ground-level detectors sometimes can observe an interaction of interplanetary distur- bances, which didn‘t reach the earth. East CMEs are especially effective, because they closing magnetic field lines beyond the orbit of earth and can interfere the restoring of cosmic ray’s intensity

Snow effect on the neutron monitor network for 2018-2019

In this article, the influence of the surrounding snow cover on the neutron monitors count rate of the world network of neutron monitors was estimated using the method of reference stations. The applied technique also makes it possible to estimate the snow cover thickness at the observation point, which was done for more than two dozen stations. A comparison of the data correction results for snow is carried out for the case of automatic correction, based on the developed algorithm, and for manual one, with an error estimate

Review of solar energetic particle models

Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to improve the scientific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data.</p

Experimental spectrum of the cosmic ray variations within rigidity range of 1-20 GV in the Earth’s orbit by the data of AMS-02

For the first time, based on the experimental data of AMS-02, a three-parameter spectrum of variations of ga - lactic cosmic rays was obtained in the range of rigidity 1- 20 GV, to which neutron monitors are most sensitive. It was found that during the period of negative polarity of the solar magnetic field, a power-law spectrum of va - riations is observed with a strong exponential decay in the region of high rigidity. When the polarity changes to positive at the beginning of the new 24th solar cycle, the spectrum of cosmic ray variations becomes purely po- wer-law. The transition to the experimentally obtained spectrum of variations will make it possible to remove a number of uncertainties and increase the accuracy of the analysis of data from the ground network of detectors. This will make it possible to retrospectively obtain fluxes of galactic protons with an average monthly resolution for the period of the space era based on ground-based monitoring

Review of Solar Energetic Particle Models

Solar Energetic Particles (SEP) events are interesting from a scientific perspective as they are the product of a broad set of physical processes from the corona out through the extent of the heliosphere, and provide insight into processes of particle acceleration and transport that are widely applicable in astrophysics. From the operations perspective, SEP events pose a radiation hazard for aviation, electronics in space, and human space exploration, in particular for missions outside of the Earth’s protective magnetosphere including to the Moon and Mars. Thus, it is critical to imific understanding of SEP events and use this understanding to develop and improve SEP forecasting capabilities to support operations. Many SEP models exist or are in development using a wide variety of approaches and with differing goals. These include computationally intensive physics-based models, fast and light empirical models, machine learning-based models, and mixed-model approaches. The aim of this paper is to summarize all of the SEP models currently developed in the scientific community, including a description of model approach, inputs and outputs, free parameters, and any published validations or comparisons with data