Observed and calculated variability of the particulate matter concentration in Moscow and in Zelenograd

The results of a comparative analysis of temporal and spatial variations in the particulate matter (PM₁₀) concentration are under consideration; the information is obtained based on the measurement data from the Mosekomonitoring network of stations and results of calculations with the CHIMERE chemistry transport model adapted for the Russian central region. The intercomparison of measurement data obtained in summer 2007 and respective calculations showed that the model provided a satisfactory reproduction of the observed temporal variability of the daily mean PM₁₀ concentration (an averaged correlation coefficient is 0.8), but systematically underestimated the absolute values of the PM₁₀ concentration. It is shown that model data quality can be significantly improved due to a simple a priori correction of the model errors. Irregularities in the spatial distribution of the PM₁₀ concentration and their dependence on meteorological conditions were revealed. The reasons of the formation of episodes of a high PM₁₀ concentration are considered.     

Estimation of transboundary transport contribution to the air pollution in the far east region using the chemistry transport model

The CHIMERE mesoscale chemistry transport model is used for the quantitative assessment of the contribution of transboundary transport of anthropogenic admixtures from China to the surface concentrations of major suspended pollutants, aerosol PM₁₀, ozone O₃, and nitrogen oxides NO_x in the Far Eastern region. Analyzed in detail are the time series of concentration of mentioned substances computed with the model taking account and not taking account of anthropogenic emissions in China. It is revealed that the transboundary transport of anthropogenic pollutants can cause the recurring episodes of manyfold increase in the concentration of PM₁₀ in the south of Khabarovsk region, as well as more rare variations of O₃ and NO_x concentration. The trajectory and synoptic analysis demonstrated that the episodes of the increase in the concentration of PM₁₀ and O₃ in the south of the region mainly depend on the carryover of air masses from northeastern China in the front part of continental cyclones.     

Air pollution over European Russia and Ukraine under the hot summer conditions of 2010

Variations in the concentrations of both primary (PM₁₀, CO, and NO_x) and secondary (ozone) pollutants in the atmosphere over the Moscow and Kirov regions, Kiev, and Crimea under the conditions of the anomalously hot summer of 2011 are given and analyzed. The concentrations of ozone, PM₁₀, CO, and NO_x in the atmosphere over the Moscow region exceeded their maximum permissible levels almost continuously from late July to late August 2010. The highest level of atmospheric pollution was observed on August 4–9, when the Moscow region was within a severe plume of forest and peatbog fires. The maximum single concentrations of ozone, which exceeded its maximum permissible level two-three times, were accompanied by high concentrations of combustion products: the concentrations of PM₁₀ and CO were also three-seven times higher than their maximum permissible concentrations. The maximum levels of air pollution were observed under the meteorological conditions that were unfavorable for pollution scattering, first of all, at a small vertical temperature gradient in the lower atmospheric boundary layer. The number of additional cases of mortality due to the exceeded maximum permissible concentrations of PM₁₀ and ozone in the atmosphere over Moscow was estimated. Under the weather conditions that were close to those for the Moscow region, the air quality remained mainly satisfactory in the Kirov region, Kiev, and Crimea, which were almost not affected by fires.     

Integrated Oceanographic Research of Discovery Gap (Eastern North Atlantic) during the Cruise 43 of the R/V Akademik Nikolaj Strakhov

Oceanology - During cruise 43 of the R/V Akademik Nikolaj Strakhov (September 21–October 9, 2019), new data were obtained on the bottom relief, sedimentation, and hydrological regime of the...     

Modeling the concentration of pollutants using the WRF-ARW atmospheric model and CHIMERE chemistry transport model

Described is a system for analyzing and forecasting the air quality in the central regions of Russia, During the operation of the system, the detailed meteorological information provided by the WRF-ARW model is used by the CHIMERE chemistry transport model for simulating the processes of transport, chemical transformation, and deposition of atmospheric minor constituents. Considered is the quality of retrieved and forecasted (with the lead time up to three days) concentrations of O₃, NO₂, NO, CO, and PM₁₀. The presented verification scores of pollutant concentrations demonstrate a relative success of the system. Demonstrated is a need in improving the data on the emissions of the air pollutants used for simulations. A procedure for the statistical correction of computed concentrations is described and verification scores of its results are given.     

Measuring the Probabilistic Photometric Redshifts of X-ray Quasars Based on the Quantile Regression of Ensembles of Decision Trees

We present empirical machine learning algorithms for measuring the probabilistic photometric redshifts (photo-z) of X-ray quasars based on the quantile regression of ensembles of decision trees. Relying on the data of present-day photometric sky surveys (e.g., SDSS, GALEX, WISE, UKIDSS, 2MASS, FIRST), the proposed methods allow one to make high-quality photo-z point predictions for extragalactic objects, to estimate the confidence intervals, and to reconstruct the full probability distribution functions for all predictions. The quality of photo-z predictions has been tested on samples of X-ray quasars from the 1RASS and 3XMM DR7 surveys, which have spectroscopic redshift measurements in the SDSS DR14Q catalog. The proposed approaches have shown the following accuracy (the metrics are the normalized median absolute deviation σNMAD and the percentage of outliers n_>0.15): σ_NMAD, n_>0.15 = 0.043, 12% (SDSS + WISE), 0.037, 8% (SDSS + WISE + GALEX) and 0.032, 8.6% (SDSS + WISE + GALEX + UKIDSS) on the RASS sample; σ_NMAD, n_>0.15 = 0.054, 13% (SDSS + WISE), 0.045, 7.6% (SDSS + WISE + GALEX), and 0.037, 6.6% (SDSS + WISE + GALEX + UKIDSS) on the 3XMM sample. The presented photo-z algorithms will become an important tool for analyzing the multi-wavelength data on X-ray quasars in the forthcoming Spectrum–Roentgen–Gamma sky survey.     

Estimation of the influence that natural fires have on air pollution in the region of Moscow megalopolis based on the combined use of chemical transport model and measurement data

Satellite measurements of the fire radiation power, measurements of atmospheric pollution in the network of GPU Mosekomonitoring stations, and the modern CHIMERE chemical transport model (CHIMERE CTM) are used for estimating the influence that forest fires have on the air pollution level in the Moscow megalopolis region during the summer of 2007. The method by which the radiation power caused by natural fires determined from satellite measurements is converted into emissions of individual model species is described. General problems related to the optimization of estimates of fire emission and the effects caused by them based on the combined use of measurement data on the composition of the atmosphere and the CTM are considered using a concrete example. It is shown, in particular, that the use of the standard least squares method for the optimization of fire emissions from leads in the general case to obtaining biased (underestimated) estimates. The results of calculations consistent with measurements show that forest fires near Moscow can occasionally be responsible for a considerable part of the air pollution observed in Moscow and its vicinities, and they can be the main reason for the high level of atmospheric pollution in some neighboring regions.     

Complex Oceanological Research during the 59th Cruise of the Research Vessel Akademik Ioffe in the Eastern North Atlantic (September–October 2021)

Oceanology - During the 59th cruise of the P/V Akademik Ioffe (September–October 2021), geophysical, sedimentological, hydrological, hydrochemical, and biological studies were carried out in...