Assessment of the first indirect radiative effect of ammonium-sulfate-nitrate aerosols in East Asia

A physically based cloud nucleation parameterization was introduced into an optical properties/radiative transfer module incorporated with the off-line air quality modeling system Regional Atmospheric Modeling System (RAMS)-Models-3 Community Multi Scale Air Quality (CMAQ) to investigate the distribution features of the first indirect radiative effects of sulfate, nitrate, and ammonium-sulfate-nitrate (ASN) over East Asia for the years of 2005, 2010, and 2013. The relationship between aerosol particles and cloud droplet number concentration could be properly described by this parameterization because the simulated cloud fraction and cloud liquid water path were generally reliable compared with Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved data. Simulation results showed that the strong effect of indirect forcing was mainly concentrated in Southeast China, the East China Sea, the Yellow Sea, and the Sea of Japan. The highest indirect radiative forcing of ASN reached ?3.47 W m^?2 over Southeast China and was obviously larger than the global mean of the indirect forcing of all anthropogenic aerosols. In addition, sulfate provided about half of the contribution to the ASN indirect forcing effect. However, the effect caused by nitrate was weak because the mass burden of nitrate was very low during summer, whereas the cloud fraction was the highest. The analysis indicated that even though the interannual variation of indirect forcing magnitude generally followed the trend of aerosol mass burden from 2005 to 2013, the cloud fraction was an important factor that determined the distribution pattern of indirect forcing. The heaviest aerosol loading in North China did not cause a strong radiative effect because of the low cloud fraction over this region.     

Observations of the atmosphere composition in the Moscow megapolis from a mobile laboratory

Doklady Earth Sciences -     

Ozone and nitric oxides in the surface air over northern Eurasia according to observational data obtained in TROICA experiments

The results of the 1995–2008 observations of the concentrations of ozone and nitric oxides in the surface air over the Trans-Siberian Railway using a mobile laboratory (the TROICA experiments) are analyzed. The features of the spatial distribution and time variability of these gases over the continent within the latitudinal belt 48°–58° N are revealed individually for polluted and background conditions. The characteristic features of their distribution are a decrease in the concentration of nitric oxides and an increase in the concentration of ozone in an eastward direction. On the whole, the process of photochemical ozone formation over the territory of Siberia is slow. Noticeable increases in the concentration of ozone are associated with both forest and steppe fires and with the transboundary transport of pollution from the countries of eastern Asia. The dry precipitation of trace gases plays a significantly larger role in Siberia than in coastal and high-altitude unpolluted regions due to powerful and long temperature inversions.     

Gaseous admixtures in the atmosphere over Moscow during the 2010 summer

In the summer of 2010, the Moscow megacity during two months was within the zone of action of a blocking anticyclone. The accumulation of pollutants in a closed air mass sharply changed the surface air quality. At the end of July-the first half of August, the extreme situation became even more complicated, because the air from regions of turf and grass fires came into Moscow. According to measurement data of the Moscow IAP RAS station, the maximal hourly mean concentrations of chemically active gases NO, NO₂, CO, O₃, and SO₂ were 175.9, 217.4, 15.8, 134.2, and 15.2 ppb, respectively. For NO₂ and CO, these values are largest over the entire decadal period of observations at the station and many times exceed the MPC level (see table). The concentrations of greenhouse gases CO₂, CH₄, and nonmethane hydrocarbons also sharply increased. Analysis of the variability of gas contents in the surface air and in the atmospheric boundary layer showed a close relation between extreme changes in the atmospheric composition and its vertical stratification.     

Aromatic volatile organic compounds and their role in ground-level ozone formation in Russia

This paper reports proton mass spectrometry data on aromatic volatile organic compounds (VOCs) (benzene, toluene, phenol, styrene, xylene, and propylbenzene) obtained in different Russian regions along the Trans-Siberian Railway from Moscow to Vladivostok, based on expedition data retrieved using the TRO-ICA-12 mobile laboratory in the summer of 2008. The contribution of aromatic VOCs to ozone formation in the cities and regions along the measurement route has been estimated quantitatively. The greatest contribution of aromatic VOCs to ozone formation is characteristic of large cities along the Trans-Siberian Railway (up to 7.5 ppbv O₃) specified by the highest concentrations of aromatic VOCs (1–1.7 ppbv) and nitrogen oxides (>20 ppbv). The results obtained are indicative of a considerable contribution (30–50%) of anthropogenic emissions of VOCs to photochemical ozone generation in the large cities along the Trans-Siberian Railway in hot and dry weather against the background of a powerful natural factor such as isoprene emissions controlling the regional balance of ground-level ozone in warm seasons.

     

Studying of biogenic volatile organic compounds in the atmosphere over Russia

The volatile organic compounds (VOCs) emitted from vegetation into the atmosphere play an important role in atmospheric chemistry and participate in the formation and growth of aerosol particles that affect the atmospheric radiation balance and the earth’s climate. A number of VOCs, such as isoprene, monoterpene, methylvinylketone, and methacrolein, whose surface concentrations were measured between Moscow and Vladivostok in the course of the Transcontinental Observations into the Chemistry of the Atmosphere (TROICA-12) experiment in July–August 2008, are considered. For the first time in Russia, a PTR-MS proton mass-spectrometer was used to measure the VOC concentrations. The continuous series of VOC concentrations in the atmosphere over the Trans-Siberian Railway were obtained, and the characteristic features of their variations were determined. The spatial distribution of the concentrations of biogenic VOC was compared with a map of Russia’s forests. It was found that the maximum concentrations of isoprene between Moscow and Vladivostok correspond to the zones of broad-leaved forests in the Far East and Primorskii Krai, and the maximum concentrations of monoterpene correspond to coniferous forests in Siberia. The obvious correlation between the concentrations of isoprene and the total concentration of methylvinylketone and methacrolein was revealed.     

Localized packets of acoustic gravity waves in the ionosphere

Using mass-spectrometric measurement data from the Dynamics Explorer 2 satellite, we investigated the distribution of medium-scale acoustic gravity waves (AGWs) at altitudes of the F-region of the ionosphere. It is shown that the planetary field of AGWs contains a regular and a sporadic component. The regular distribution of AGWs involves active polar areas (where the ionosphere is highly disturbed) and a relatively calm equatorial area. Sporadic AGWs are isolated and spatially localized wave packets that are distinguished against the background of the regular distribution of the wave field. We generated a directory containing observations of sporadic AGW for the period January–February 1983 and performed a statistical analysis of their relation to earthquakes.