Analysis of the spectrum of 27-day GCR variations in 2015–2016.

• 27-day variations of GCR flux according to measurements of AMS-02 and others. • Parameterization of the amplitude-energy spectrum of variations. • Consequences of the force-field model for short-term modulation. This work presents the results of the analysis of 27-day variations in the flux of galactic protons registered by STEREO, SOHO, and AMS-02 in 2015–2016. We calculate variations' amplitude using several different approaches and propose a description of its energy dependence in the range of magnetic rigidity from approximately 0.3 to 100 GV. We also analyse variations of the solar modulation potential, which is the only parameter of force-field model, and consider the possibility of describing the 27-day variations of galactic cosmic rays within the framework of this model. It is shown that rigidity dependence of the 27-day variations amplitude cannot be properly described using this simple approximation. [ABSTRACT FROM AUTHOR]