Purpose. The purpose of the paper is to study the effect of sea ice cover on the intensity of the polar mesoscale cyclone that took place on March 15–16, 2021 over the Barents Sea.

Methods and Results. To study the cyclone numerically, the polar version of the mesoscale WRF model was used. In the performed numerical experiment, the sea ice in the computational domain was replaced by water, the temperature of which was 271.46 K. To identify the main factors amplifying the polar mesoscale cyclone, the balance equation for the space-average cyclone kinetic energy was applied. The basic components of the kinetic energy balance equation were considered: the work of pressure gradient force, Fpres, the advection effect and the work of inertial forces Adv, and also the work of turbulent friction force Ffric. It was found that the removal of sea ice from the computational domain had resulted in a decrease of the polar mesoscale cyclone intensity. The values of Fpres, Adv and Ffric in the control run were quantitatively compared to those in the experiment, and it was shown that the intensity decrease had become mainly the result of a decrease in Fpres and Adv.

Conclusions. Decrease of Fpres is a consequence of the fact that in the control run, the northern part of the polar mesoscale cyclone was located above the sea ice, and the surface air temperature in this part was 25–30℃ lower than in the southern one. The removal of sea ice led to an increase in surface air temperature at the cyclone periphery and to a decrease in the surface pressure drop between the vortex center and periphery. The Adv decrease is related to deformation of the cyclone in the experiment, which resulted in the increase in the fluctuating component of the azimuthal and radial velocities. Both of these factors have led to a decrease of the polar mesoscale cyclone intensity in the experiment.