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To improve the simulation of the heterogeneous oxidation of SO2 and NOx in the presence of authentic mineral dust particles under ambient environmental conditions, the explicit kinetic mechanisms were constructed in the Atmospheric Mineral Aerosol Reaction (AMAR) model. The formation of sulfate and nitrate was divided into three phases: the gas phase, the non-dust aqueous phase, and the dust phase. In particular, AMAR established the mechanistic role of dust chemical characteristics (e.g., photoactivation, hygroscopicity, and buffering capacity) in heterogeneous chemistry. The photoactivation kinetic process of different dust particles was built into the model by measuring the photodegradation rate constant of an impregnated surrogate (malachite green dye) on a dust filter sample (e.g., Arizona test dust -- ATD -- and Gobi Desert dust -- GDD) using an online reflective UV--visible spectrometer. The photoactivation parameters were integrated with the heterogeneous chemistry to predict the formation of reactive oxygen species on dust surfaces. A mathematical equation for the hygroscopicity of dust particles was also included in the AMAR model to process the multiphase partitioning of trace gases and in-particle chemistry. The buffering capacity of dust, which is related to the neutralization of dust alkaline carbonates with inorganic acids, was included in the model to dynamically predict the hygroscopicity of aged dust. The AMAR model simulated the formation of sulfate and nitrate using experimental data obtained in the presence of authentic mineral dust under ambient sunlight using a large outdoor smog chamber (University of Florida Atmospheric Photochemical Outdoor Reactor, UF-APHOR). Overall, the influence of GDD on the heterogeneous chemistry was much greater than that of ATD. Based on the model analysis, GDD enhanced the sulfate formation mainly via its high photoactivation capability. In the case of NO2 oxidation, dust-phase nitrate formation is mainly regulated by the buffering capacity of dust. The measured buffering capacity of GDD was 2 times greater than that of ATD, and consequently, the maximum nitrate concentration with GDD was nearly 2 times higher than that with ATD. The model also highlights that in urban areas with high NOx concentrations, hygroscopic nitrate salts quickly form via titration of the carbonates in the dust particles, but in the presence of SO2, the nitrate salts are gradually depleted by the formation of sulfate. [ABSTRACT FROM AUTHOR]

East Asia is one of the world's largest sources of dust and anthropogenic pollution. Dust particles originating from East Asia have been recognized to travel across the Pacific to North America and beyond, thereby affecting the radiation incident on the surface as well as clouds aloft in the atmosphere. In this study, integrated analyses are performed focusing on one trans-Pacific dust episode during 12–22 March 2015, based on space-borne, ground-based observations, reanalysis data combined with Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), and the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem). From the perspective of synoptic patterns, the location and strength of Aleutian low pressure system largely determined the eastward transport of dust plumes towards western North America. Multi-sensor satellite observations reveal that dust aerosols in this episode originated from the Taklimakan and Gobi Deserts. Moreover, the satellite observations suggest that the dust particles can be transformed to polluted particles over the East Asian regions after encountering high concentration of anthropogenic pollutants. In terms of the vertical distribution of polluted dust particles, at the very beginning, they were mainly located in the altitudes ranging from 1 km to 7 km over the source region, then ascended to 2 km–9 km over the Pacific Ocean. The simulations confirm that these elevated dust particles in the lower free troposphere were largely transported along the prevailing westerly jet stream. Overall, observations and modeling demonstrate how a typical springtime dust episode develops and how the dust particles travel over the North Pacific Ocean all the way to North America. [ABSTRACT FROM AUTHOR]

The Taklimakan Desert (TD) and Gobi Desert (GD) are two of the most important dust sources in East Asia, and have important impact on energy budgets, ecosystems and water cycles at regional and even global scales. To investigate the contribution of the TD and the GD to dust concentrations in East Asia as a whole, dust emissions, transport, and deposition over the TD and the GD in different seasons from 2007 to 2011 were systematically compared, based on the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Dust emissions, uplift, and long-range transport related to these two dust source regions were markedly different due to differences in topography, elevation, thermal conditions, and atmospheric circulation. Specifically, the topography of the GD is relatively flat, and at a high elevation, and the area is under the influence of two jet streams at high altitudes, resulting in high wind speeds in the upper atmosphere. Deep convective mixing enables the descending branch of jet streams to continuously transport momentum downward to the mid-troposphere, leading to enhanced wind speeds in the lower troposphere over the GD which favors the vertical uplift of the GD dust particles. Therefore, the GD dust was very likely to be transported under the effect of strong westerly jets, and thus played the most important role in contributing to dust concentrations in East Asia. Approximately 35% and 31% of dust emitted from the GD transported to remote areas in East Asia in spring and summer, respectively. The TD has the highest dust emission capabilities in East Asia, with emissions of about 70.54 Tg yr in spring, accounting for 42% of the total dust emissions in East Asia. However, the TD is located in the Tarim Basin and surrounded by mountains on three sides. Furthermore, the dominant surface wind direction is eastward and the average wind speed at high altitudes is relatively small over the TD. As a result, the TD dust particles are not easily transported outside the Tarim Basin, such that most of the dust particles are re-deposited after uplift, at a total deposition rate of about 40 g m. It is only when the TD dust particles are uplifted above 4 km, and entrained in westerlies that they begin to undergo a long-range transport. Therefore, the contribution of the TD dust to East Asian dust concentrations was relatively small. Only 25% and 23% of the TD dust was transported to remote areas over East Asia in spring and summer, respectively. [ABSTRACT FROM AUTHOR]

An inverse modeling system for estimating Asian dust emissions was developed by combining the GEOS-Chem chemical transport model with the Green's function method. We applied the system to two heavy dust storms that occurred in 2014 (10-25 March and 24 May to 5 June), using surface-based polarization optical particle counter (POPC) observations at Fukuoka. Validation by independent observation datasets, including POPC measurements and PM10 observations at Seoul, showed that the use of a posteriori dust emissions improved overestimations in the a priori simulation and achieved much better agreement with observations. Satellite observations, surface synoptic observations, and modeled wind fields indicated that the major dust source region differed between the two dust storms; the major dust outbreak of one storm occurred in the northeastern Gobi Desert, whereas that of the other occurred in the southern Gobi Desert. The a posteriori dust emissions successfully reproduced this difference. Thus, the inverse modeling system developed in this study was able to improve the estimation of not only the intensity but also the geographical distribution of dust emissions. [ABSTRACT FROM AUTHOR]

Using eight years (2006–2014) of passive (MODIS/Aqua and OMI/Aura) and active (CALIOP/CALIPSO) satellite measurements of aerosols, we yield a three-dimensional (3D) distribution of the frequency of occurrence (FoO) of aerosols over China. As an indicator of the vertical heterogeneity of aerosol layers detected by CALIOP, two types of Most Probable Height (MPH), including MPH_FoO and MPH_AOD, are deduced. The FoO of “Total Aerosol” reveals significant geographical dependence. Eastern China showed much stronger aerosol FoD than northwestern China. The FoO vertical structures of aerosol layer are strongly dependent on altitudes. Among the eight typical ROIs analyzed, aerosol layers over the Gobi Desert have the largest occurrence probability located at an altitude as high as 2.83 km, as compared to 1.26 km over Beijing–Tianjin–Hebei. The diurnal variation (nighttime–daytime) in MPH_AOD varies from an altitude as low as 0.07 km over the Sichuan basin to 0.27 km over the Gobi Desert, whereas the magnitude of the diurnal variation in terms of MPH_AOD is six times as large as the MPH_FoO, mostly attributable to the day/night lidar SNR difference. Also, the 3D distribution of dust and smoke aerosols was presented. The multi-sensor synergized 3D observations of dust aerosols, frequently observed in the zonal belt of 38°N–45°N, is markedly different from that of smoke aerosols that are predominantly located in the eastern and southern parts. The 3D FoO distribution of dust indicates a west-to-east passageway of dust originating from the westernmost Taklimakan Desert all the way to North China Plain (NCP). The findings from the multi-sensor synergetic observations greatly improved our understanding on the long-range aerosol dispersion, transport and passageway over China. [ABSTRACT FROM AUTHOR]

Initial mapping of secondary succession in places disturbed by mining of the Khan Khentii Strictly Protected Area in Mongolia shows a possible innovative direction taken by afforestation in order to prevent further expansion of the Gobi Desert in northern Mongolia. The study results from the knowledge of secondary succession of mined areas, which are classified as the remains and consequences of prospecting and mining work dated to the Soviet times. Ongoing succession on sites affected by mining is very slow. In quarry dumps and canavas, herb layer has not been recovered despite the fact that the prospecting and mining activities had finished more than 30 years ago. Herbs biodiversity is very poor in these areas. Conversely, representatives of the tree layer, especially Larix sibirica and Populus tremula, are found far from the continuous forest; they colonized sites located within the aridized steppe. We assume that the main factor of successful tree growth on the mining activities remains consists in the humidity condensation due to and caused by the specific shape of the canavas and dumps. Trees prosperity on these extreme habitats can be ensured particularly in the early stages of growth when the tree roots are unable to reach the groundwater table. Detail mapping of quantitative and qualitative parameters of trees shows that the dump is an ideal shape of self-watering condensation mound for forest growth and can prevent the desertification as well. [ABSTRACT FROM AUTHOR]

Although Mesozoic fossils are quite common in the Gobi Desert of Central Asia, it is often difficult to correlate among different localities because of a dearth of rocks amenable to absolute dating. Specifically, correlating between the eastern Gobi Desert and more western localities has been challenging. Here we give a Santonian-Campanian age for the enigmatic Zos Canyon beds in the Nemegt basin. This is based on the occurrence of the primitive ornithopod dinosaur Haya griva at both eastern Gobi exposures of the Javkhlant Formation and the Zos Canyon locality. [ABSTRACT FROM AUTHOR]

When Marco Polo journeyed to the court of Kublai Khan in 1271 he traversed a great sandy desert filled with 'extraordinary illusions' that became known as the Gobi desert. The continued use of term Gobi, first appearing in 1706, is a rare case of Mongolian ascendancy over the Chinese. Exploration of the Gobi as a mapping term seeks to understand how the desert was conceptualised and identified as a geographical region, an economic sphere and a political presence. Historically contested between China and Russia with Mongolia as a proxy, the desert is now home to 25 million people, mineral wealth and rapid development. As attention increases and the strategic region integrates into global systems, knowledge of the perceived desert boundaries becomes germane. In our era of data and demarcation with place names used to confer prior possession we examine how the Mongolian term 'gobi' rather than the Chinese equivalent 'shamo' prevailed. China dominates the region without asserting physical control; in fact, the term ' Gobi desert' is not recognised in China's geographical lexicon. Does past suzerainty offer insight to the present and potential future scenarios in the desert? New contextualisation presents the Gobi as a multi-dimensional space that, rather than a past construction, portends an emergent consciousness no longer isolated and insulated from regional and global currents. [ABSTRACT FROM AUTHOR]

In a desert ecosystem, water plays a very important role in most ecological properties and processes. Located in the hinterland of the Eurasian continent, Xinjiang is covered by the sandy Gobi Desert, which is dotted with patchy oases. Land desertification is becoming a serious problem as the rapid growth in population and increased exploitation of water and soil resources increases. However, water that could be used to combat desertification is relatively scarce. Most of the conventional water resources are used in industry, agriculture and for social and economic development. Therefore, we need to develop non-conventional water (NWRU) for biological sand control. After 30 years of research, four types of NWRU technologies have been developed. (1) Non-irrigation afforestation technology using moisture, stored in the humid sandy subsurface, is applicable in the regions where precipitation is more than 100 mm per annum, of which most is snow fall; (2) water harvesting afforestation technology that collects snowmelt water and rainfall has been developed in the regions where precipitation is more than 100 mm and where the land is overlain by a low-permeability soil; (3) flood water irrigation afforestation technology, using summer floods, is feasible in regions with abundant flood water and where their occurrence coincides with the vegetation growing season; and (4) drip irrigation afforestation technology, using underground brackish water, has been developed in regions where abundant underground brackish water can be supplied through irrigation systems. This paper reviews the four types of NWRU technologies for biological sand control in Xinjiang and provides some technical references for combating desertification in similar areas around the world. [ABSTRACT FROM AUTHOR]