Study of the formation of the methane field in the atmosphere over northwestern Russia

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.     

Study of the factors determining anomalous variability of carbon dioxide total column amount over St. Petersburg

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).     

Analysis of variability of the CO, NO2, and O3 contents in the troposphere near St. Petersburg

The space-time variability of the fields of CO, NO₂, and O₃ 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, NO₂, and O₃ in the troposphere is estimated for March 2006. A comparison of the measurements of the total CO content and the tropospheric NO₂ 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.     

NO<Subscript>2</Subscript> content variations near St. Petersburg as inferred from ground-based and satellite measurements of scattered solar radiation

An automatic spectral complex developed at the Institute of Physics, St. Petersburg State University, is described. This complex is used for regular ground-based spectroscopic measurements of the total NO₂ content in the vertical column of the atmosphere during the twilight and daylight hours of the day near St. Petersburg (Petrodvorets). In 2004–2006, a number of ground-based twilight measurements of the total NO₂ content were obtained near St. Petersburg, and variations in the NO₂ content in the troposphere were estimated from the results of daytime ground-based measurements. An example of the spatial annual mean distribution of the NO₂ content (central and northern Europe, northwestern Russia) based on the data of satellite measurements over the period 2003–2005 is presented. This example demonstrates the main sources of anthropogenic pollution. An increase in the mean annual contents of tropospheric NO₂ near Moscow and St. Petersburg is preliminarily estimated for the entire period of satellite observations with the GOME instrument at about 30–40% over ten years.     

Regional space monitoring of nitrogen dioxide in the troposphere

Satellite instruments for the routine global monitoring of NO₂ in the atmosphere—the Global Ozone Monitoring Experiment (GOME) on the ERS-2 satellite, the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) on the ENVISAT satellite, the Ozone Monitoring Instrument (OMI) on the AURA satellite, and the GOME-2 on the MetOp satellite—are briefly described. It is shown that the error of measuring the NO₂ total column amount (∼10% for the background conditions in the troposphere) substantially increases in regions subject to anthropogenic pollution. Examples of practically using multiyear satellite measurements for the regional monitoring of NO₂ in the troposphere are presented, including mapping the tropospheric NO₂ in Russia, identifying the weekly and annual cycles in tropospheric NO₂ variations for megalopolises (St. Petersburg, Moscow, Paris), and estimating the long-term linear trend in 1995–2007.     

Variations in the column-average dry-air mole fractions of CO2 in the vicinity of St. Petersburg

The results obtained from ground-based spectroscopic measurements of column-average dry-air mole fractions of CO₂ 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 CO₂ 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 CO₂ mixing ratio with its summer minimum was observed in 2009. In July 2010 and 2011, the values of the CO₂ mixing ratio increased apparently due to high air temperatures. In 2010 an additional contribution to this increase in the CO₂ mixing ratio could have been made by strong natural fires.     

Nitrogen dioxide in the air basin of St. Petersburg: Remote measurements and numerical simulation

The results of ground-based and satellite spectroscopic measurements of the tropospheric NO₂ content near St. Petersburg in January–March 2006 are presented. It is shown that the increased concentrations of NO₂ observed in St. Petersburg and its vicinities in this period were caused by NO₂ accumulation due to unfavorable weather conditions, which is confirmed by an analysis of meteorological data and the results of a numerical simulation of the dispersion of urban air pollutants. Data from satellite and ground-based measurements agree with each other satisfactorily (a correlation coefficient of 0.5) and with model calculations of tropospheric NO₂ conducted for the coordinates of a station of ground-based measurements (a correlation coefficient of 0.6). The HYSPLIT dispersion model also made it possible to estimate the scale of the NO₂ spatial-temporal variability in the near-surface layer in the vicinities of St. Petersburg.     

Integral emission of nitrogen oxides from the territory of St. Petersburg based on the data of mobile measurements and numerical simulation results

The results of spectroscopic measurements of tropospheric NO₂ content performed on a closed route along the circular road around the city of St. Petersburg in 2012, 2014, and 2015 are presented. A procedure for determining the integral emission of NO _x based on the data of measurements on the route enveloping the sources under study is described. An analysis of the experimental data together with the results of a numerical simulation of air pollutant dispersion (the HYSPLIT model) provided an estimate of the total volume of NO _x emitted by all sources located inside the circular road. The average emission rate of NO _x according to the sources of the megacity of St. Petersburg is 57000 t/yr, which correlates satisfactorily with the official data of a municipal inventory of the sources of air pollution (62000–63 000 t/yr).     

Spatial–Temporal CO2 Variations near St. Petersburg Based on Satellite and Ground-Based Measurements

Izvestiya, Atmospheric and Oceanic Physics - The results of studying spatial–temporal CO2 variations near St. Petersburg in 2014–2017 based on satellite measurements (OCO-2 satellite)...     

Variations of the total content of carbon monoxide over Moscow megapolis

The results of the carbon monoxide total content measurements over Moscow and Zvenigorod for 2005–2008 are compared with the same data sets for Moscow 1986–2005 and Beijing, 1992–2007. Two identical medium resolution diffraction spectrometers (resolution 0.2 cm^?1) with solar tracking system were used. The CO total content measured simultaneously over the city and over Zvenigorod Scientific Station (ZSS) of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (60 km west from Moscow). This method allows to isolate an urban part of CO content. The acoustic locator SODAR LATAN-3 measurements permitted us to study the influence of the carbon monoxide ventilation conditions upon level of pollution. Correlation coefficients between the urban part of CO content and average wind speed for cold and warm seasons were obtained. The data sets analysis showed a preeminent effect of the wind within boundary layer (up to 300 m) over the CO ventilation. The urban part of the CO content hasn’t increased in spite of more than quintuple increase of the motor-vehicles number in Moscow. An increase of the rural CO total column for the 1970–1985 has transformed into its virtually stable amount in between of 1986 to 2000, changed then to a decrease for 2001–2008. We noted the 2008 as “the year of the CO total column minimum” over the past decade. The effect of urban CO sources influence on the CO total column in rural area is small, i.e. on a level of 3% of the total number of measurements. The number of extremal daily values for Moscow is estimated as 5%, and 20% for Beijing.     

Time variations of the total CO content in the atmosphere near St. Petersburg

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.     

Ground-based measurements of total column of hydrogen chloride in the atmosphere near St. Petersburg

We present ground-based spectroscopic measurements of the total hydrogen chloride in the atmosphere of Peterhof near St. Petersburg from April 2009 to March 2012. The well-known computer code SFIT-2 (Zephyr-2) was used to interpret the spectra of the solar IR radiation. The random and systematic errors of total column (TC) HCl measurements did not exceed 3.8 and 4.5%. The seasonal behavior of TC HCl in Peterhof is characterized by the presence of a maximum in March–April and a minimum in October–November. There are also extremely small TC HCl values in January–February. The time behavior obtained for Peterhof agrees well with data from nearest stations in the NDACC international network. The ground-based measurements of the TC HCl were compared with satellite measurements with the help of ACE-FTS and MLS instruments. The direct comparisons of coincident (within a day) and collocated (within 500 km) satellite and ground-based measurements showed a correspondence of results within their total errors.     

Identifying anthropogenic sources of nitrogen oxide emissions from calculations of Lagrangian trajectories and the observational data from a tall tower in Siberia during the spring-summer period of 2007

The task of identifying climatically significant regional anthropogenic emissions and estimating their contribution to the variability of nitrogen oxides observed at a monitoring station is considered on the basis of NO and NO₂ surface concentrations measured at the Zotino background observation station (60°26′ N, 89°24′ E, Krasnoyarsk Territory). The approach used is based on an estimation of the conditional probability of polluted air arriving from individual regions by using the results of calculating backward Lagrangian trajectories in the lower troposphere. It is established that the contribution of air masses supplied from industrial regions in the south of the Krasnoyarsk Territory to episodes of high concentrations of nitrogen oxides (>0.7 ppb) is larger than the contribution from cities and towns located in the south of Western Siberia. The results indicate that anthropogenic sources of pollution substantially affect the balance of minor gases in the lower troposphere on a regional scale and that this factor must be taken into account when observational data from the Zotino background station are analyzed and interpreted.     

Ozone Temporal Variability in the Subarctic Region: Comparison of Satellite Measurements with Numerical Simulations

Fourier and wavelet spectra of time series for the ozone column abundance in the atmospheric 0–25 and 25–60 km layers are analyzed from SBUV satellite observations and from numerical simulations based on the RSHU and EMAC models. The analysis uses datasets for three subarctic locations (St. Petersburg, Harestua, and Kiruna) for 2000–2014. The Fourier and wavelet spectra show periodicities in the range from ~10 days to ~10 years and from ~1 day to ~2 years, respectively. The comparison of the spectra shows overall agreement between the observational and modeled datasets. However, the analysis has revealed differences both between the measurements and the models and between the models themselves. The differences primarily concern the Rossby wave period region and the 11-year and semiannual periodicities. Possible reasons are given for the differences between the models and the measurements.     

Estimation of water-vapor and ozone transport in the upper troposphere-lower stratosphere and fluxes through the tropopause during the field campaign at the Sodankyla station (Finland)

Processes of mass exchange through the tropopause at extratropical latitudes are studied. For this purpose, balloon data on ozone and water vapor obtained during the LAUTLOS field campaign were analyzed and a trajectory model was used to analyze the origin of air masses and to calculate fluxes through the tropopause. The results of observations and trajectory modeling showed that tropospheric air masses penetrated into the stratosphere by no more than ～2.5 km above the tropopause level during the campaign. Both tropospheric and stratospheric particles are present in this mixing layer. Backward trajectories showed that, at the anticyclone boundary, tropospheric air penetrates into the stratosphere in the form of fine fibrous structures (filaments). The fluxes through the tropopause were also quantitatively estimated by the Wei method with the use of forward and backward trajectories. The spatial structure of the fluxes through the tropopause coincides with the regions of the tropopause inclination and its folds. The absolute values of the fluxes calculated with the use of the Wei method decrease, depending on the length of trajectories at the expense of the filtering-out of a shallow reversible exchange. It is shown that the exchange depth can be controlled by both vertical fluxes in the troposphere and changes in the level of the tropopause itself. The use of isentropic and three-dimensional trajectories made it possible to estimate the contribution of nonadiabatic processes to the stratosphere-troposphere exchange.     

Intercomparison of satellite and ground-based ozone total column measurements

Ozone total column (OTC) measurements made in 2009–2012 near St. Petersburg by a Fourier Transform Infrared (FTIR) spectrometer (Peterhof, St. Petersburg State University (SPbSU)), an M-124 filter ozonometer, and a Dobson spectrophotometer (Voeikovo, MGO), as well as measurements made by a spectrometer ozone monitoring instrument (OMI) (onboard the AURA satellite) have been analyzed and compared. Comparisons have been performed both between ensembles of ground-based measurement data, as well as between ground-based and satellite data. It has been shown that the standard deviation for all devices is 2.5–4.5%; here, the FTIR and Dobson instruments measuring the direct sun are in better agreement with OMI than the M-124 ozonometer measuring the zenith-scattered solar radiation as well. A seasonal cycle in discrepancy with amplitude of 1.5% has been detected between two series of OTC measurements made by M-124 and OMI instruments for a total of 850 days. In fall and winter, the ground-based measurements underestimate the OTC values in comparison with satellite data; in spring and summer, the situation is reversed: ground-based data overestimate the OTC values. Also, it has been revealed that FTIR measurements systematically overestimate the OTC values in comparison with other instruments: from 1.4% (for Dobson) to 3.4% (for OMI). Taking into account the spatial and temporal discrepancy of independent ensembles of measurements and an analysis of standard deviations between ground-based and satellite measurement data, the FTIR spectrometer (SPbSU) can be recommended for OTC satellite data validation.     

Ground-based spectroscopic measurements of the total nitric acid content in the atmosphere

The results of the first ground-based spectroscopic measurements in Russia of the total content (TC) of nitric acid in the atmosphere near St. Petersburg over the period April 2009–October 2011 are presented. These measurements show a substantial seasonal trend of the HNO₃ TC with maximal values in the winter period and early in the spring and minimal values in the summer time. The seasonal trends and variations in the daily mean values of HNO₃ TC near St. Petersburg in the winter and spring periods agree well with observations at the Kiruna station of the international NDACC network.     

Stratospheric NO2 content according to data from ground-based measurements of solar IR radiation

Atmospheric NO₂ content data obtained from regular ground-based measurements of solar IR radiation in the St. Petersburg region using a spectrometer with a high spectral resolution are analyzed. The absorption spectra of the NO₂ multiplet in the vicinity of ～2915 cm^?1 allow one to obtain data on variations in the stratospheric total content of NO₂ in 2009–2011. The accuracy of these data is estimated from their comparison with data obtained from independent ground-based and satellite measurements. The parameters of the seasonal cycle of the stratospheric content of NO₂ are estimated. The body of data accumulated during these measurements in the IR region made it possible to isolate the component of a daytime photochemical increase in the stratospheric content of NO₂ and estimate its rate.     

Spectroscopic measurements of total CFC-11 freon in the atmosphere near St. Petersburg

On the basis of ground based measurements of the infrared spectra of solar radiation with a high spectral resolution, estimates of total CFC-11 freon content in the atmosphere near St. Petersburg in January and May 2009 have been yielded in Russia for the first time. These data are conformed to various independent measurements within the limits of spectroscopic measurement errors.     

Comparison of Ground-Based Measurement Results of Total Ozone near St. Petersburg

Izvestiya, Atmospheric and Oceanic Physics - This paper compares the results of ground-based measurements of the total ozone content (TOC) near St. Petersburg for the period of 2009–2020. The...