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Simulation of present day climate with a new version of climate model developed in INM RAS is considered. The model differs from a previous version by the change in cloudiness and condensation scheme, that leads to higher sensitivity to CO2 increase. The changes are included also in calculation of aerosol evolution, land snow, atmospheric boundary layer parameterizations and other blocks. The model is capable to reproduce near surface air temperature, precipitation, sea level pressure, cloud radiation forcing and other parameters better than previous version. The largest improvement can be seen in simulation of temperature in tropical troposphere, polar tropopause, and surface temperature in the Southern ocean. Simulation of climate changes in 1850–2021 by two model versions is considered.

A technique is proposed for evolution equation that estimates the impact of different terms in phase change for oscillations with different frequencies. The impact is normalized in such way that sum of impacts for all terms equals 1. Proposed technique is applied for study of quasibiannual oscillation of zonal wind in equatorial stratosphere produced in 500 year preindustrial run with climate model of Institute of Numerical Mathematics RAS. The impact of nonorographic and orographic gravity wave drag and advection by zonal mean vertical wind to the phase change of model quasibiannual oscillation. It is shown that nonorographic wave drag is main mechanism responsible for phase change (the impact equals 1.58), vertical advection slows down phase change (impact is –0.74), and the impacts of other terms are small.

The experimental seasonal forecasts of the INM-CM5 climate model were used as input data for the temperature-time phenological model of birch dusting. Within the framework of the joint model, a test technology was developed for seasonal forecasting of the timing of the beginning of birch dusting in the European territory of Russia. Verification of this technology on seasonal retrospective forecasts of the INM-CM5 model (1991–2019) showed an adequate reproduction of the birch dusting start dates calculated for the same period according to the ERA5 reanalysis. The mean systematic errors are ±2 days, and the spatial correlation coefficients are above +0.84. The forecasts of the date of dusting start in 2022, calculated from the experimental operational seasonal forecasts of the INM-CM5 model with a monthly lead-time and with a zero lead-time, are also evaluated. It is shown that the errors in forecasting the beginning of dusting are ±5–10 days, and the forecasts with a one-month lead-time have fewer errors. The obtained results allow us to conclude that the seasonal forecast of the surface temperature of the INM-CM5 model can be used as input information for the temperature-time phenological model for the operational forecast of the timing of the start of birch dusting in the European territory of Russia.