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Results of a series of spectroscopic measurements of the tropospheric NO2 content carried out on a closed route of the Ring Road of St. Petersburg in different seasons in 2012, 2014, 2015, and 2016 are considered. A unified approach to the interpretation of all experimental data using numerical modeling of air pollution spread and a priori information about the spatial distribution of its anthropogenic sources has significantly improved the accuracy of determining the integral NOx emissions. The total NOx volume, reduced to gross annual anthropogenic emissions from the territory of St. Petersburg, amounted to 81 000 ± 17 000 t. This value slightly exceeds the air pollution city inventory official data (from 61 000 to 63 000 t per year), consistent within the error margin with the estimate obtained earlier on the basis of similar mobile measurements in the spring of 2019 (75 000 ± 26 000 t per year). [ABSTRACT FROM AUTHOR]

The issues related to the intraseasonal variability and predictability of regional scale atmospheric processes in the Northern Hemisphere are considered. To identify the latter, circulation indices characterizing large-scale modes of atmospheric variability are used. An assessment is made of the regional intraseasonal variability of the atmospheric processes in the summer and winter seasons of 1991–2020. A study of practical predictability of regional atmospheric processes is carried out using the global semi-Lagrangian model developed at the Institute of Numerical Mathematics, Russian Academy of Sciences, jointly with the Hydrometeorological Center of Russia, as well as reanalyses of the European Center for Medium-Range Weather Forecasts on weekly and monthly time scales. It is concluded that, beyond the first prognostic week, the quality of deterministic (ensemble average) forecasts drops sharply. In winter, the Pacific–North American Oscillation region is an exception, where a signal is traced not only over the first, but also over the second forecast week. The application of probabilistic forecasts makes it possible to increase the time interval of predictability compared to the deterministic approach from one week to a month. The largest errors are revealed in the forecasts of circulation regimes in the Northwest Atlantic and in the North Pacific, in the regions of the most significant intraseasonal variability. The results are planned to be used in the operational practice of intraseasonal forecasting of the North Eurasian Climate Center (NEACC). [ABSTRACT FROM AUTHOR]

Total column amounts (TCAs) of various climatically important atmospheric gases have been determined in Peterhof for the period between 2009 and 2018. These measurements were performed using a Bruker 125HR ground-based IR Fourier transform spectrometer, which registered the spectra of direct solar radiances. We estimated the trends for TCAs of 13 climatically important gases for the first time in Russia. For nine of them, these estimates are reliable. Trends of the main greenhouse gases, CO2, CH4, and N2O, determined with high accuracy (~0.02%), are positive and equal 0.52, 0.42, and 0.28% per year, respectively. The comparison of methane trend estimates with earlier ones demonstrates that in recent years the trend of methane TCAs near St. Petersburg has been increased. Moreover, we observe the negative trends in TCAs of tropospheric ozone (–0.75 ± 0.56% per year), CFC-11 and CFC-12 (~–0.5–1.0% per year), and ClONO2 (–2% per year). Trends for HF and HCFC-22 TCAs near St. Petersburg are positive, providing ~1–2% per year. [ABSTRACT FROM AUTHOR]

The results of studying spatial–temporal CO2 variations near St. Petersburg in 2014–2017 based on satellite measurements (OCO-2 satellite) and ground-based spectroscopic and local measurements are presented. According to satellite data, the full amplitude of the spatial–temporal variations for the average CO2 mixing ratio (XCO2) amount to 57.7 ppm (over 14%). The maximal XCO2 spatial variations during 1 day of observations (March 17, 2015) were 46.8 ppm (more than 10%). A comparison of CO2 satellite and ground-based spectroscopic measurements has shown that ground-based measurements in the NDACC observation system after the correction of systematic differences from the TCCON system can be used to validate satellite measurements. Ground-based local measurements of the near-surface CO2 mixing ratio at Peterhof do not correlate either with spectroscopic ground-based or satellite measurements due to both mesoscale CO2 variations and significantly different spatial averaging kernels of direct and remote measurements. [ABSTRACT FROM AUTHOR]

Abstract: The short-term variability of the methane column has been analyzed based on ground-based observations and numerical modeling at the St. Petersburg NDACC station for 2009-2016. The methane variability for different atmospheric altitude layers is presented. Short-term methane variability is found to be significant compared to long-term trends. The results of numerical experiments with the global chemistry-transport model of the troposphere and stratosphere demonstrate that short-term methane variability is basically defined by methane concentration changes between an altitude of 5 km and 20 km. [ABSTRACT FROM AUTHOR]

The results of the first long-term (2009-2017) ground-based spectroscopic measurements of the total content (TC) of a number of freons in Russia are presented. According to measurements in Peterhof, TCs of CFC-11 and CFC-12 decrease at a rate of ~0.6% per year and TC of HCFC-22 grows at a rate of ~2.7% per year, which is in good agreement with independent measurements. The seasonal course of freon TC in the area of St. Petersburg is registered: highs of CFC-11 and CFC-12 are observed in summer and lows are in late winter and spring. For the HCFC-22 TC, the opposite seasonal course is observed, with a maximum in winter and a minimum in summer. [ABSTRACT FROM AUTHOR]

The annual cycle and long-term trend of the methane total column in the atmosphere over the Petergof station (St. Petersburg State University) are analyzed on the basis of data obtained from Fourier-transform infrared spectrometry and EMAC-model calculations. The amplitude of the annual cycle of the total column of CH amounts to 2.1 and 1.5% according to experimental and model data, respectively. For the atmospheric column-averaged mole fraction of CH, the amplitude of its annual cycle is smaller than that for its total column and amounts to 1.1 and 0.6% according to experimental and model data, respectively. The results of local continuous measurements of surface CH concentrations showed that, in 2013, the atmospheric column-averaged mole fractions of CH and the amplitudes of diurnal variations in its local concentration were characterized by the same dynamics of seasonal variations. An analysis made on the basis of simulation results showed that atmospheric conditions (under which Fourier-transform IR measurements were performed) could increase the amplitude of the annual cycle of the total column of CH 2.5 times when compared to the true one. The results of Fourier-transform IR measurements and EMAC-model calculations showed that, during 2009-2012, the atmospheric concentration of CH increased at a rate of ~0.2% per year. If measurement data obtained in 2013 are added, this rate decreases to ~0.13% per year. [ABSTRACT FROM AUTHOR]

The results of 2-year (2010-2012) measurements of the concentrations of organic carbon (OC) and elemental carbon (EC), which were taken at the Zotino Tall Tower Observatory (ZOTTO) Siberian background station (61° N, 89° E), are given. Despite the fact that this station is located far from populated areas and industrial zones, the concentrations of OC and EC in the atmosphere over boreal forests in central Siberia significantly exceed their background values. In winter and fall, high concentrations of atmospheric carbonaceous aerosol particles are caused by the long-range transport (~1000 km) of air masses that accumulate pollutants from large cities located in both southern and southwestern regions of Siberia. In spring and summer, the pollution level is also high due to regional forest fires and agricultural burning in the steppe zone of western Siberia in the Russian-Kazakh border region. Background concentrations of carbonaceous aerosol particles were observed within relatively short time intervals whose total duration was no more than 20% of the entire observation period. In summer, variations in the background concentrations of OC closely correlated with air temperature, which implies that the biogenic sources of organic-particle formation are dominating. [ABSTRACT FROM AUTHOR]

We present a joint analysis of data obtained by Fourier transform infrared measurements of CH and EMAC model calculations for Petergof station (St. Petersburg State University) in 2009-2012. The systematic differences between observed and calculated data are 1.3% and 0.3% for the values of total column and atmospheric column-averaged mole fraction of methane, respectively. The high correlation for experimental and model data of the total column ( r = 0.8) indicates that EMAC reproduces the total variability of the methane total column in the atmosphere due to meteorological processes. Using model data, we have analyzed the effect of meteorological conditions typical for Fourier transform IR observations on the resulting estimates of the mean values of total column and column-averaged mole fraction of CH4. We have shown that there can be systematic shifts (up to ~0.4%) in the experimental estimates for the mean value relative to the 'true' value. This fact should be taken into account in comparing the climatological or model data with the results of Fourier transform IR measurements, especially for stations with a relatively small number of observation days. [ABSTRACT FROM AUTHOR]

The column-average mole fraction of methane measured with hyperspectral methods of ground-based Fourier transform spectroscopy at the Physical Department of St. Petersburg State University (59.9° N, 29.8° E) in 2009-2012 is compared with similar data measured from the Japanese GOSAT satellite. The average mole fraction of methane $X_{CH_4 } $ from GOSAT data version V01.xx are lower by 17-21 ppb than the corresponding value obtained from ground-based measurements with a standard deviation of about 13 ppb. For the GOSAT data version V02.xx, this difference is about 2 ppb on average, with a standard deviation of about 18 ppb. This corresponds to differences between data on $X_{CH_4 } $ from the GOSAT satellite and from the TCCON and NDACC networks. [ABSTRACT FROM AUTHOR]

The results obtained from ground-based spectroscopic measurements of column-average dry-air mole fractions of CO in the atmosphere over the St. Petersburg region are given for the period April 2009-October 2011 (∼900 measurement runs, 151 measurement days). These results show significant variations in the CO mixing ratio in the atmosphere over the St. Petersburg region. The minimum value of this mixing ratio (373.1 ppm) was observed on April 27, 2011, and its maximum value (420.8 ppm) was observed on February 10, 2010. The typical seasonal behavior of the CO mixing ratio with its summer minimum was observed in 2009. In July 2010 and 2011, the values of the CO mixing ratio increased apparently due to high air temperatures. In 2010 an additional contribution to this increase in the CO mixing ratio could have been made by strong natural fires. [ABSTRACT FROM AUTHOR]

We analyzed measurements of the total carbon monoxide (CO) content in the atmosphere in the region of St. Petersburg (59.88°N, 29.83° E; 20 m above sea level) in the period from 1995 to 2009. The average annual behavior for the entire measurement period has a maximum in February-March and a minimum in July with an amplitude of ∼20%. In the absence of strong forest fires in the European part of the Russian Federation and Siberia, the annual minimum of the total CO content is usually recorded in August-September. In winter 1995-2009 (November-January), there was a decrease in the total CO content with a gradual shift in the maximum of the annual behavior from January (1995-1999) to February (2000-2004) and March (2005-2009). The total CO content in January-February 2009 was ∼20% lower than the multiyear average level. Estimates of the linear trend for the maximum, minimum, and average values for the period of 1996-2009 showed an absence of statistically significant long-term changes in the total CO content. A spectral analysis of data showed that the spectral components with periods of 12, 14, 17, 24, and 46 months are extracted with 80% confidence. It is shown that the irregular component of the time series of the total CO content (calculated for the period from May to September) agrees well with data on the areas of the forest fires and on the volume of the burnt forest and that 1999, 2001, 2005, 2007, and 2009 can be considered 'background' years with the least numbers of forest fires. [ABSTRACT FROM AUTHOR]

The space-time variability of the fields of CO, NO, and O concentrations and contents in the troposphere of northwestern Russia is analyzed on the basis of experimental data and the results of numerical modeling. The influence that the St. Petersburg emission has on the concentrations and contents of CO, NO, and O in the troposphere is estimated for March 2006. A comparison of the measurements of the total CO content and the tropospheric NO content with the results of modeling showed a qualitative and, in come cases, quantitative agreement between the results of calculations and experimental data. When synoptic conditions are determined, the St. Petersburg train can be detected at a distance of more than 300 km, which can affect the atmospheric air quality in adjacent countries. [ABSTRACT FROM AUTHOR]

The results of measuring the methane content in the entire atmospheric thickness over the St. Petersburg region are given for 1991–2007. It is shown that, within this period, the mean annual cycle of the total methane content is characterized by its maximum values in December–January and its minimum values in June–August when the annual-cycle amplitude amounts to ∼3.6%. In this case, the annual variations in the total methane content may differ significantly from the mean annual cycle obtained in some years. A statistically significant linear trend of the total CH4 content has not been revealed for 1991–2007. The obtained values of the linear-trend index have opposite signs in the winter and summer months (positive for January 0.6 ± 0.2%/year and February 0.4 ± 0.2%/year and negative for July 0.3 ± 0.2%/year and August 0.2 ± 0.1%/year). This fact suggests the tendency for an increase in the amplitude of the annual cycle of the total CH4 content. The results of a spectral analysis of a series of data on the total CH4 content show that, for 1991–2007, the following harmonics are pronounced with a confidence of 95%: 12 months (annual harmonic), 32 months (quasi-biennial oscillations), and 55 months (4.5 years), which are also pronounced in the series of meteorological parameters and total ozone content. [ABSTRACT FROM AUTHOR]

The influence of air invasions from the upper troposphere on the CO total column amount is studied on the basis of spectroscopic measurements of the CO total column amount, backward trajectories of air-mass motions (the HYSPLIT model), and meteorological data. It is shown that the observed invasions of substratospheric and upper-troposphere air masses determine the minimum CO total column amount in late January-late March. The invasion of air masses from the upper troposphere can result in a decrease in the CO total column amount to 30% (of its mean values). Using January 31, 2000, as an example, we show the influence of the invasion of Arctic air masses from the upper troposphere on the CO total column amount in the St. Petersburg region: the results of measurements of the CO total column amount in the St. Petersburg region and at the Kiruna polar station (NDACC) are in agreement to within 1% if the vertical transport of air masses is taken into account. Thus, for a correct combined analysis of measurement data on the CO total column amount for different observation stations, it is necessary to use data on air-mass trajectories. [ABSTRACT FROM AUTHOR]

Results of spectroscopic measurements of the carbon dioxide total column amount near St. Petersburg during forest fires in the period from August to September 2002 are analyzed. The HYSPLIT model is used to calculate air-mass trajectories and CO distribution on a mesoscale in this period. The HYSPLIT model simulations and measurements of carbon dioxide total column amount yield an estimate of the specific intensity of CO emission in a Pskov forest fire on August 28–September 8, 2002, equal to 0.17–0.26 kg m2. This estimate can be used for an estimation of the integral CO emission from fires in northwestern Russian forests and for model simulations of atmospheric CO concentration fields. The estimate of the CO emission from forest fires that is obtained from ground-based measurements can also be made on the basis of satellite measurements if they contain information on CO in the lower tropospheric layers (0 to 2 km). [ABSTRACT FROM AUTHOR]

Major processes of generation of the methane field in the atmosphere over northwestern Russia have been studied on the basis of measured surface concentration and total content of methane in the environs of St. Petersburg, air-mass trajectories, and a three-dimensional regional pollution transport model. It is shown that the contribution of methane emission from an industrial center to the total column amount of methane is no more than 2% of its average value. At the same time, because of this emission, the surface methane concentration in the environs of St. Petersburg varies by as much as 50%. The origin of air masses arriving at the site of measurements influences both the total content and the surface concentration of methane. The air masses that passed over the continental part of western and eastern Europe are characterized by the values of total content and surface concentration of methane that are about 4% higher than those in the air masses formed over the ocean, which come to the region from the northwest. The regional transport model for greenhouse gases satisfactorily describes the results of surface measurements and adequately simulates observed tendencies in the change of total methane content. An estimate of the integral emission of methane into the atmosphere from St. Petersburg and its industrial suburbs is about 100 kt per year. [ABSTRACT FROM AUTHOR]