Alexandr Gochakov

The paper describes the configuration of the COSMO-Ru6Sib system with a horizontal grid spacing of 6.6 km adapted to regional conditions. The COSMO-Ru2Sib configuration with a horizontal grid spacing of 2.2 km is also considered. The results of modifying this configuration using weather radar data assimilation as well as urban canopy parameterizati...

Western Siberia is exposed to extreme wind events caused by severe convective storms. However, our knowledge on such storms in Siberia is still fragmentary compared to other parts of the world primarily due to the lack of weather radar data. These storms cause substantial damage, which signifies the need for comprehensive assessment of their charac...

The changes in the response of air temperature to the variations in the instantaneous blocking frequency (IBF) (GHGS > 0) between the periods 1979-1999 and 2000-2020 are studied. Blocking patterns, which are the spatial distributions of the coefficients of correlation between the IBF and the 1000 hPa temperature field, are used as the main characte...

In 2019, the southern region of Eastern Siberia (located between 45° N and 60° N) experienced heavy floods, while the northern region (between 60° N and 75° N) saw intense forest fires that lasted for almost the entire summer, from 25 June to 12 August. To investigate the causes of these natural disasters, we analyzed the large-scale features of at...

The socioeconomic impacts caused by floods in the south of Eastern Siberia (SES), and the expected increase in precipitation extremes over northern Eurasia, have revealed the need to search for atmospheric circulation patterns that cause extreme precipitation events (EPE) in SES, as well as their changes. We investigate the circulation patterns cau...

Climatology and variability of anticyclonic (AC-type) and cyclonic (C-type) wave breaking in the region of the subtropical jet stream are investigated using the previously developed method for identifying and clustering Rossby wave breaking events. Potential vorticity at an isentropic surface of 350 K from the ERA-Interim and ERA5 reanalyses are us...

This paper presents results of numerical estimates of vertical temperature profiles in the COSMO and ICON NWP models. Data from two vertical profilers, an MTP-5 microwave temperature profiler and a classic AVK-type radiosonde, are used for the estimates. Mean errors, correlation coefficients, and root-mean-square errors are calculated for different...

The joint use of atmospheric chemistry transport and transformation models and observational data makes it possible to solve a wide range of environment protection tasks, including pollution sources identification and reconstruction of the pollution fields in unobserved areas. Seamless usage of different measurement data types can improve the accur...

Climatology and variability of anticyclonic (AC-type) and cyclonic (C-type) wave breaking in the region of the subtropical jet stream are investigated using the previously developed method for identifying and clustering Rossby wave breaking events. Potential vorticity at an isentropic surface of 350 K from the ERA-Interim and ERA5 reanalyses are us...

Air quality monitoring systems differ in composition and accuracy of observations and their temporal and spatial coverage. A monitoring system’s performance can be assessed by evaluating the accuracy of the emission sources identified by its data. In the considered inverse modeling approach, a source identification problem is transformed to a quasi...

This paper addressed two topics linked to air quality monitoring data processing: using heterogeneous data in inverse modeling and predicting the inverse modeling result before the inverse problem solution. Both topics are addressed within the unified sensitivity operator-based inverse modeling framework. We think that the results will be interesti...

Within the scenario approach, the observability of traffic emission sources is estimated from indirect monitoring data. What is new is that an approach based on sensitivity operators is used to estimate observability, which allows us to obtain a family of quasilinear operator equations for the source identification problem. This allows both solving...

In the approach to the inverse problems, based on the sensitivity operators, the inverse problem is transformed into the family of quasi-linear operator equations. The sensitivity operator is constructed of the ensemble of the adjoint problem solutions corresponding to different adjoint problems source functions. Hence, from the theoretical point o...

Many large-scale dynamic phenomena in the Earth’s atmosphere are associated with the processes of propagation and breaking of Rossby waves. A new method for identifying the Rossby wave breaking (RWB) is proposed. It is based on the detection of breakings centers by analyzing the shape of the contours of potential vorticity or temperature on quasima...

An application of sensitivity operator-based algorithms to an inverse modeling scenario of urban air quality is presented. A source identification problem and a concentration field continuation problem are solved and analyzed. The analysis of the sensitivity operator allows one to obtain a preliminary estimate of the source identification problem s...

The Selenga is one of the crucial transboundary rivers of the semi-arid Northern Eurasia belt. The Selenga basin is located in Mongolia and Russia, and it is 83.4% of the Lake Baikal basin. Atmospheric precipitation is the primary source of the river supply; most of its amount falls like rain from June to August (about 70% of the annual). In the pr...

Variational approach and sensitivity theory methods are used to construct algorithms for solving the problems of environmental forecast and design. When studying the behavior of the model in the parameter space, sensitivity functions are calculated as partial derivatives of the target functionals with respect to the model parameters. The sensitivit...

This paper presents preliminary results of the effectiveness analysis of an air quality forecasting system for the city of Novosibirsk with replenishment of the missing information on emission sources by solving an inverse problem with urban monitoring network data. In solving the inverse problem, a priori information about the location and mode of...

The performance of a direct variational data assimilation algorithm with quasi-independent data assimilation at individual steps of the splitting scheme has been studied in a realistic scenario of air pollution assessment in the city of Novosibirsk by monitoring system data. For operation under conditions of a sparse monitoring network, an algorith...

The results of WRF-CHEM model simulation of dispersal of anthropogenic emissions from the Norilsk industrial zone are verified against data of aircraft sensing performed in August 2004. It is shown that the WRF-CHEM v3.5.1 model configuration selected adequately reproduces the meteorological parameters obtained during the 2004 measurement campaign....

A class of wavelet filtration algorithms with two-parameter threshold functions is considered. An algorithm is proposed for solving the problem of choosing two threshold values, which allows estimating their optimal values with acceptable accuracy.

A new algorithm is proposed for estimating optimal threshold values in thresholding algorithms of wavelet filtration of signals and images. Numerous computational experiments are performed to compare this threshold with threshold values widely used in wavelet filtration algorithms. Application of the proposed threshold is demonstrated to ensure sub...

Operation principles of locally spatial filtration algorithms and wavelet filtration algorithms are described. Numerous computational experiments are performed with filtration of two different images distorted by noise with different statistical natures (white, color, and pulsed). Based on the analysis of the results obtained, recommendations on us...

The proposed algorithm calculates its own filtration factor for each coefficient of the wavelet expansion of a noisy signal. The optimal filtration factor depends on the signal-to-noise ratio, which is estimated with a specially constructed iterative procedure. The limit points of this procedure are determined. A computational experiment performed...