Variability of Extra Tropical Atmospheric Circulation and Periodic Trajectories in Simplified Models of Atmospheric Dynamics

Izvestiya, Atmospheric and Oceanic Physics - The possibility for approximate basic statistical characteristics of atmospheric models using periodic trajectories (closed solutions of equations of...     

Simulation of modern climate with the new version of the INM RAS climate model

The INMCM5.0 numerical model of the Earth’s climate system is presented, which is an evolution from the previous version, INMCM4.0. A higher vertical resolution for the stratosphere is applied in the atmospheric block. Also, we raised the upper boundary of the calculating area, added the aerosol block, modified parameterization of clouds and condensation, and increased the horizontal resolution in the ocean block. The program implementation of the model was also updated. We consider the simulation of the current climate using the new version of the model. Attention is focused on reducing systematic errors as compared to the previous version, reproducing phenomena that could not be simulated correctly in the previous version, and modeling the problems that remain unresolved.     

Statistical characteristics of barotropic atmospeheric system and its unstable periodic solutions

This paper is devoted to the problem of approximating an invariant measure and statistical characteristics of barotropic atmospheric model with the help of its periodic trajectories. In this procedure orbits are taken into account according to their weights defined by the orbit instability characteristics. The method comes from the dynamical systems theory where in several specific case (for hyperbolic systems in particular) unstable periodic orbits define the system invariant measure. In our study we show that the system PDF could be reconstructed with the error less than 10% provided that the optimal orbit weight function is chosen.     

Nature of the Decrease in Global Warming at the Beginning of the 21st Century

Variations in the temperature of the Earth’s surface over the period 1850–2014 are reproduced and analyzed using seven historical calculations in the INM-CM5 climate model following the scenarios suggested for the CMIP6 project of comparison of climate models. In all calculations, the mean surface temperature increased by 0.8 K to the date of final calculation (2014), which is consistent with observations. The periods of accelerated warming (1920–1940 and 1980–2000) and its stabilization (1950–1975 and 2000–2014) are correctly reproduced by the model. The decrease in global warming of 2000–2014, which is hardly reproduced by the models in the CMIP5 experiment, is reproduced due to the more precise scenario of variation in the solar constant of CMIP6 protocols. The spatial structure of warming for last 30 years is also reproduced by the model.

     

Connection of periodic orbits and variability patterns of circulation for the barotropic model of atmospheric dynamics

We have investigated the relationship between periodic trajectories of barotropic atmospheric model and the modes of the model variability. In particular, we have studied the nature of “25 day” mode of variability (Branstator, 1987; Kushnir 1987). This mode arises as a first complex empirical orthogonal function (or “Hilbert EOF” according to (H. von Storch, Zwiers)) for a given system and is a dominant rotational component of the system dynamics. It was shown that the mode structure coincides with several least unstable periodic orbits of the system. The phase portrait of the system in the plane of the first complex EOF has regular shape with maximum of the probability density function in the vicinity of these weakly unstable periodic orbits.     

Construction of response operators to small external forcings for atmospheric general circulation models with time periodic right-hand sides

Fluctuation-dissipation relations make it possible to connect the response operators of system statistical characteristics to small external perturbations with the statistical characteristics of the unperturbed system (providing statistical stationary of the system). This gives a possibility to estimate the sensitivity of the system directly from modeling or observational data. The problem becomes much more complex if the right hand side of the system contains a component periodically dependent on time (as applied to the problems of modeling the atmosphere, this corresponds to the annual cycle regime experiments). Recently obtained generalized fluctuation-dissipation relations (see Majda and Wang, 2010 [11]) allow (at least theoretically) to construct response operators in the former case as well. In this work we formulate the algorithm for constructing an approximate response operator and test it numerically on the example of the National Center for Atmospheric Research (NCAR) CAM3 atmospheric general circulation model.     

Formation of Extreme Anomalies in the Total Electron Content According to Data from Linear Theory

Geomagnetism and Aeronomy - Under the assumption that the evolution of the total electron content (TEC) in a quiet ionosphere can be described within the framework of the linear dynamic-stochastic...     

Potential Predictability and Forecasting of the State of the Field of Anomalies of the Total Electron Concentration from Observational Data

Geomagnetism and Aeronomy - An attempt is made in this study to evaluate the potential predictability of the TEC field (its deviation from the weekly average) at hourly time scales based on...     

Simulation of Possible Future Climate Changes in the 21st Century in the INM-CM5 Climate Model

Izvestiya, Atmospheric and Oceanic Physics - Climate changes in 2015–2100 have been simulated with the use of the INM-CM5 climate model following four scenarios: SSP1-2.6, SSP2-4.5, and...