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• The paper exemplifies China's increasing efforts on road ecology protections. • We demonstrate a strategic approach for positioning and designing wildlife passages. • This approach is useful when high-resolution data are out of availability. • The goitered gazelle is the most dominant species in the area. • Underpasses are proposed with a minimum width of 12 m and a minimum height of 3.5 m. This paper reports on the design of wildlife crossing structures (WCSs) along a new expressway in China, which exemplifies the country's increasing efforts on wildlife protection in infrastructure projects. The line and belt transect method, the surface water survey, and the sign-tracking investigation were used to determine the target species in the study area and the quantity, candidate locations, size, and type of the WCSs. The intensity index and encounter rate showed that the ibex (Capra ibex), argali sheep (Ovis ammon), and goitered gazelle (Gazella subgutturosa) are the main ungulates in the study area. Among them, the goitered gazelle is the most widely distributed species. Underpass WCSs were proposed based on the expert knowledge and crossing hotspots estimated using survey results. The mean distance between estimated hotspots and their nearest proposed WCSs is around 341 m. In addition, those proposed WCSs have a width of no less than 12 m and height of no lower than 3.5 m, which is believed to be sufficient for ungulates in the area. Given the limited availability of high-resolution movement data and wildlife-vehicle collision data during the road's early design stage, the approach demonstrated in this paper facilitates the practical spatial planning and provides insights into designing WCSs in a desert landscape. [ABSTRACT FROM AUTHOR]

The Hobq Desert (HD) locates at the northern margin of the Ordos Plateau, China and the transition zone to the Hetao Basin. It is one of the main proximal deserts of the Loess Plateau, and its formation was controlled by the evolution of the Yellow River and the Ordos Plateau. It is still worthy of discussing the regional structure to enhance the understanding of the desert formation and paleoenvironment, especially with the additional works in the eastern part. Geophysical methods including gravity, magnetic, EM (electromagnetic) are often used to analyse the regional and near-surface structure. As for drilling records, they could show the lithology sequence directly and be applied for the environmental study (e.g., OSL dating). Therefore, in this paper, we used the satellite gravity data, GPR (Ground Penetrating Radar), TEM (Transient electromagnetic method) and drilling records with borehole resistivity data to analyse the desert structure from different scales and the paleoenvironment. Trough the upward continuation and Park-Oldenburg calculation for the gravity data, the thickness of Quaternary deposits is 0.85–1.55 km. The inferred faults indicated the performance of the Hetao Basin and the Ordos Plateau's uplift in Pleistocene, which also contributed to HD's formation and existing topography. A three-part structure within 350 m was revealed in the profile at eastern HD by EM data. The upper layer within 80–90 m was the aeolian dry sand, the middle one was mainly fluviolacustrine saturated sand with the occurrence of clay and grey calcareous root tubes, and the lower one might be the aeolian sand. This near-surface structure was consistent to the western part, and the forming period for the sand in the upper zone was thereby estimated no earlier than 80 Ka. Moreover, during this period, millennial-scale changes in paleo-effective moisture occurred although it was dominated by the arid climate. [ABSTRACT FROM AUTHOR]

Abstract Multiangle Implementation of Atmospheric Correction (MAIAC) is a new aerosol algorithm developed to retrieve aerosol optical depth (AOD) over land using the time series data to dynamically isolate aerosol and land contributions. However, there are still no comprehensive research on the quality of MAIAC AOD over China. In this paper, 1 km MAIAC AOD over China were examined against ground-based measurements to evaluate the performance of the data. In general, Aqua and Terra MAIAC retrievals have a high correlation coefficient (0.924 for Aqua and 0.933 for Terra) with ground-based observations and there are more than 72% of retrievals falling within the Expected Errors (EE = ±(0.05 + 0.2*AOD)). We found that the accuracy of MAIAC AOD is related with the AOD magnitude, aerosol size, seasons and surface types. In spring and summer, the AOD bias was influenced by both aerosol model and surface reflectance estimation. We also found that the aerosol model is the main source of AOD bias over desert regions. These results indicated that the MAIAC AOD could be used as a new aerosol data source for air quality and climate studies in China. Highlights • A comprehensive research was conducted to evaluate the performance of MAIAC aerosol products over China. • The accuracy of MAIAC AOD is related with the AOD magnitude, aerosol size, seasons, and surface types. • Good performance of Aqua and Terra MAIAC retrievals are shown. • The MAIAC AOD bias is mainly influenced by aerosol model in desert regions. [ABSTRACT FROM AUTHOR]

One of the key and difficult points in seismic data processing is seismic data denoising. Under the influence of the acquisition environment, the collected seismic data usually have low signal-to-noise ratio (SNR) and low resolution. In desert region of western China, different from other regions, the random noise there has complex characteristics of non-Gaussian, non-stationary and non-linearity. Its main frequency is quite low and its spectral overlap with those of effective signals. Moreover, large amount of data and intelligent requirements make traditional denoising methods encounter difficulties. In addition, the existing deep learning denoising methods also reveal two problems: first, they can only effectively suppress simple seismic noise such as Gaussian noise. But for the case of desert noise, they usually mistakenly judge noise as effective signals and destroy signal characteristic structure. Second, what is more important, in supervised-based methods paired noisy and pure data are usually used as training set. However, there is no noise-free data in actual desert seismic data, which severely limits the processing performance of supervised-based networks. Thus, a new parameter-shared variational auto-encoding adversarial network (PS-VAAN) is proposed for desert seismic data denoising in this paper. This new method includes two encoders, two generators and two discriminators. It can realize domain conversion from noisy data domain to pure data domain. We construct relatively complete unpaired pure and noisy data training sets for training, and design reconstruction loss function and adversarial loss function to optimize network parameters. Moreover, cycle-consistency loss is introduced to make sure two domains mapping into the same space. Compared with the state-of-art denoising methods on synthetic and actual seismic records, the proposed method not only has superior denoising ability, but also has strong feature extraction and fitting ability to recover effective signals with almost no energy loss. • Desert seismic noise has the characteristics of low frequency and non-stationary. • This paper designs a parameter-shared variational auto-encoding adversarial network. • The network use unpaired noisy and pure training sets to optimize parameters. • The proposed method has a strong ability to recover effective signals from noise. [ABSTRACT FROM AUTHOR]

The arid regions of northwestern China are dominated by extensive areas of mobile sand dunes. These features cause environmental problems and exert global climatic impacts; however, due to the lack of systematically-applied indicators of aeolian activity, direct evidence of past changes in aeolian activity is unreliable, especially for aeolian sand source regions. In this paper, we analyze the end-member (EM) distributions of various types of surface soil across the Tengger Desert in northwestern China, and devise a sensitive proxy for aeolian activity using a spatio-temporal substitution approach. This proxy is then used to evaluate a Quaternary aeolian succession and to understand the response of aeolian activity to regional climate change. Our results suggest that gradual increases in the coarse-grained EM components 3–5 reflect enhanced dune mobility and reduced vegetation coverage, which are a direct function of the intensity of regional aeolian activity. In the aeolian section, coarse- and medium-grained sand layers resemble modern semi-mobile and mobile dunes, whereas fine-grained sand layers are analogous to vegetated fixed/semi-fixed or semi-mobile dunes. Combining this record with independent multi-proxy evidence from the same section leads us to conclude that strong aeolian activity coincided with a dry climate, sparse vegetation cover, and strong surface winds during the Last Glacial Maximum, and that these conditions gradually attenuated at the beginning of the Last Deglacial. These inferences are in accord with independent paleoclimate records from this region, confirming that the intensity of aeolian activity in the southeastern Tengger Desert is closely associated with large-scale climate change. Our findings show that our EM proxy can be used to infer the intensity of aeolian activity and to reliably reconstruct the evolution of deserts in northwestern China. [Display omitted] • Coarse grain-size End-members (EM) 3–5 are a proxy of the strength of aeolian activity. • This proxy is applied to a palaeo-aeolian sequence to reconstruct the history of desert evolution. • Aeolian activity was closely associated with large-scale climate change. [ABSTRACT FROM AUTHOR]

In this paper, we examine the Early to Middle Holocene evolution of a prominent group of ground-water fed lakes in the southeastern hinterland of the Badain Jaran Desert (BJD) of northwest China. Specifically, we describe a sediment profile record from the Taoerlegetu (TR) palaeolake basin using multiple proxies of total organic carbon (TOC), total nitrogen (TN), C/N ratio, δ13C org , grain size and mineral composition based on a well-dated trench profile. As C/N values suggest that sedimentary organic matter mainly originated from aquatic plants, δ13Corg values can be used as a qualitative proxy for water level because aquatic plants in different biotopes (water depth) have different δ13C values. Our results show that from 10.9 to 9.1 cal kyr B.P., water level rose slowly, and aquatic macrophytes occupied the lake basin. From 9.1 to 5.5 cal kyr B.P., water level reached an even higher level and phytoplankton replaced macrophytes as the major contributor to organic matter. The humid episode of the lakes in the hinterland of the BJD in the early Holocene might be related to the increased groundwater supply from the northeast region of the Tibet Plateau. These findings are consistent with earlier studies of lacustrine and peat sediments found in periphery of the modern lake group, which indicate that their geographic extent may have been larger in the past. A relative drought period recorded in the studied succession from 8.5 to 8.0 cal kyr B.P. marks an interval of reduced ground-water transport from the Tibet Plateau. This interval probably corresponds to the "8.2 ka cold event" and provides evidence that this widespread climate episode influenced groundwater processes across inland Asia. • The δ13C org value could be used as a qualitative indicator for the change of water level. • Lakes in the hinterland of the Badain Jaran Desert shows different evolution progress with these in the edge. • The main water source of lakes in the hinterland of the BJD in the Early Holocene comes from the Tibet Plateau. [ABSTRACT FROM AUTHOR]

Grassland ecosystems are an important part of terrestrial ecosystems and are important for building ecological barriers, promoting the pastoral economy, and maintaining social stability. In recent decades, grasslands in northern China have undergone extensive degradation due to the combined effects of global climate change and the anthropogenic overuse of grasslands. An understanding of the spatial distribution of grassland degradation species is helpful for evaluating the process of grassland degradation and formulating appropriate protective measures. This is important for grassland degradation monitoring. To address the limitations of traditional ground surveys and realize intelligent remote sensing grassland degradation monitoring tasks, we use unmanned aerial vehicle (UAV) hyperspectral remote sensing technology to collect data on vegetation species in desert grasslands. In this paper, we propose a local-global feature enhancement network (LGFEN) for the classification of desert grassland species. The method uses the local feature enhancement (LFE) module and global feature enhancement (GFE) module to extract local and spatial information from hyperspectral images (HSIs), respectively. In addition, the introduction of the convolutional block attention module (CBAM) refines the features of HSIs, improving the stability of the classification performance. The results show that the proposed method has superior classification performance compared with existing HSI classification methods. With only 10 training samples per class, the overall accuracy, average accuracy, and kappa coefficient of the proposed method were 98.61%, 97.61%, and 0.9815, respectively. The proposed method provides a new approach for high-precision and high-efficiency dynamic monitoring of grassland ecosystems. • A local-global feature enhancement network (LGFEN) is proposed. • Improved efficiency of grassland degradation monitoring. • The LFE module is proposed to implement global feature extraction. • Compared with existing methods, LGFEN has better performance. [ABSTRACT FROM AUTHOR]

In the desert region of northwest China, the frequency of wind-sand disasters is high. All types of concrete buildings built in this area face severe wind erosion due to high wind speed, resulting in varying degrees of wind-erosion damage to concrete. To accomplish intelligent identification of concrete wind-erosion damage, a concrete wind erosion experiment was conducted in the laboratory, and a concrete wind-erosion damage dataset was generated under the interference of water stains, scratches, shooting distance, and background noise. This paper combined with transformer theory to improve YOLO-v4 and proposed an object detection algorithm called MHSA-YOLOv4 suitable for wind-erosion damage of concrete. The results demonstrate that MHSA-YOLOv4 exhibits improved object detection performance than YOLO-v3, improved YOLO-v3, and YOLO-v4. On the test set, ACC, Precision, Recall, and mAP of MHSA-YOLOv4 are 91.30%, 91.52%, 92.31%, and 0.89, respectively. MHSA-YOLOv4 can accurately identify wind-erosion damage of concrete images under different test conditions, which reflects strong robustness. The applicability of computer vision technology to the intelligent identification of wind-erosion damage on concrete has been verified. • The dataset of wind-erosion of concrete was established to simulate the spalling of concrete. • A object detection algorithm called MHSA-YOLOv4 was proposed based on Transformer. • MHSA-YOLOv4 can detect concrete wind-erosion damage with high-precision. [ABSTRACT FROM AUTHOR]

As a part of the INQUA project “A Global Digital Database and Atlas of Quaternary Dune Field and Sand Seas”, 337 age records from the desert dunes of China and 20 from Mongolian dune fields have been compiled in the database. This has opened the possibility of exploring and synthesizing the Quaternary environmental changes in the Asian mid-latitudes dune fields directly from the on-site aeolian sand archives. This paper assessed the sand dune chronologies in terms of geographical distribution, data quality and their implications for late Quaternary palaeoenvironmental reconstructions. The available ages are concentrated mainly in the last 20 ka and many are from the fields of stabilized dunes in the eastern portion of the desert belt in northern China. The number of records and the ratio between the records of stable state and the total records could act as a proxy for the palaeoenvironmental interpretation. The aeolian sand activities deciphered from the chronological data in the eastern portion of the desert belt in northern China show a reasonable correlation with the general global climatic curves at the glacial–interglacial timescales. The limited aeolian sand records from the glacial period, however, hamper the understanding of the detailed features (e.g., forms and processes) of the dune fields during glacial times. In the last two millennia, however, there has not been any meaningful correlation between aeolian dune activity and climatic variation at the centennial time scales, probably due to the complexity of the aeolian sand systems and human interventions. Extending the coverage of dune chronology both temporally and spatially is urgently needed for a full understanding of the environmental changes in the dune fields. [ABSTRACT FROM AUTHOR]

• A stochastic shock model is proposed to investigate seed banks persistence. • The lower bound of the probability of seed bank persistence under stochastic shocks is presented. • The seed bank persistence of artificial sand-binding vegetation was investigated. Seed bank persistence plays a significant role in maintaining the sustainability of artificial vegetation in desert regions. However, the periods of droughts after each rainfall event form a series of stochastic shocks and result in depletion of the seed bank. Understanding seed bank persistence under stochastic shocks is a crucial prerequisite to evaluation of the sustainability of artificial vegetation under ongoing drought, but few studies have addressed the response of soil seed bank persistence to frequent stochastic shocks in deserts. In this paper, a stochastic shock model describing the input–output process of the seed bank is proposed based on modern risk theory to explore seed bank persistence of artificial vegetation in desert regions. The existence condition of the seed bank and the lower bound of the probability of seed bank persistence under stochastic shock after a long time were theoretically determined. As a verification of the theoretical model, seed bank persistence of artificial sand-binding vegetation on the southeastern margin of the Tengger Desert in China was investigated based on field observation and experimental and empirical data. The numerical results reveal that the seed bank of artificial sand-binding vegetation will always exist under stochastic shocks with a probability greater than 95%, suggesting that in the long-term succession process the current artificial sand-binding vegetation will likely maintain the development trend toward the adjacent natural vegetation. [ABSTRACT FROM AUTHOR]

In China, medium sand is widely used for engineering applications. However, over quarrying of medium sand to meet the demand for urbanization has led to the environmental issue. The arid area of Northwest China, which has high concentration of desert could provide sufficient supply of desert sand for engineering applications. In this paper, desert sand was used to replace medium sand to produce desert sand mortar (DSM). The uniaxial compression test was performed on the DSM undergoing elevated temperature treatment, and the stress-strain curves of the DSM after different temperatures were obtained. The effects of temperature and desert sand replacement rate (DSR) on the peak stress, peak strain, elastic modulus, Poisson's ratio, and mass loss rate of DSM was analysed. The test results showed that with the increase of DSR, the peak stress and elastic modulus of DSM first increased and then decreased. As the temperature increased, the Poisson's ratio of the DSM decreased first and then increased. Based on regression analysis, the relationships between peak stress, peak strain, elastic modulus, Poisson's ratio of DSM, temperature, and DSR were obtained. At the same time, a one-parameter compression constitutive equation of DSM after the elevated temperature was established. Since the equation has only one parameter, the calculation process was greatly simplified based on ensuring the calculation results. The model was in high agreement with the test results. This equation can provide a reference for further studies in the field of mechanical properties of DSM and desert sand concrete (DSC) after elevated temperatures. • Desert sand was used as fine aggregate to prepare mortar. • The mechanical properties of desert sand mortar after high temperature were studied. • The compression constitutive model of desert sand mortar after high temperature was established. [ABSTRACT FROM AUTHOR]

This paper presents the climatology and changes in atmospheric visibility (AV) in China during 1980–2017 based on adjusted data from an extended station network. The relationships between AV and the wind speed (WS) from the near surface to the troposphere (850 hPa to 200 hPa) are analysed. The mean visibility at 582 qualified stations in China is 22.03 km, with the highest in summer (25.37 km) and lowest in winter (18.92 km). The annual mean AV has decreased at most stations and all seasons across China since the 1980s. Most regions show a decreasing AV trend mainly before 2005 and an increasing trend in recent years, possibly related to the emission reduction policies in China. The AV has a significant positive correlation with the near-surface WS in all seasons, with the largest correlation coefficient of 0.84 in summer and the smallest in winter. The AV also has a positive correlation with the WS in the lower troposphere in most of China, except in some inland desert regions. Additionally, the long-term trends of WS, surface temperature (T), relative humidity (RH) and surface pressure (Ps) were analysed at each station across China. The results show that both decreasing WS and increasing T could well account for the decreasing trend in AV. The changes in RH and Ps are at least not the main drivers. Overall, the "best" ("worst") visibility corresponds to the largest (smallest) WS near the ground and in the lower troposphere, but such correspondence tends to overturn towards the upper troposphere. Image 1 • The annual mean AV has decreased at most stations and all seasons across China since the 1980s. • On average the AV has significant positive correlation with the near-surface and the lower troposphere WS for all seasons. • AV exhibits a significant negative correlation center over southeastern China in mid-upper troposphere. • Both decreasing WS and increasing T could well account for the decreasing trend in AV. [ABSTRACT FROM AUTHOR]

The variations and trends of the AOD (aerosol optical depth, at 550 nm) from 2000 to 2017 in mainland China were analyzed in this paper with monthly, seasonal, and yearly mean data, derived from the NASA combined MODIS Dark Target and Deep Blue AOD retrievals. Particularly, the distribution and variation of AOD over the desert region of the southern Xinjiang basin which is one of the major Asian dust sources was described. To investigate the seasonal and yearly variation trends of the AOD over China, the linear trend was analyzed for each point during the 18 years. The correlations between AOD and terrain, Gross Domestic Product and Population Density were also analyzed. The results were as follows. (1) In China, the all-year high value ( τ M O D I S > 0.50) of the AOD occurred in the Sichuan basin, the Two Lakes Plain, North China, the Yangtze River Delta, the Pearl River Delta, the Guangzhong Plain, and the Jingjinji Metropolitan Region. In particular, the southern Xinjiang basin is not the high value center. While the all-year low value ( τ M O D I S < 0.20) of the AOD occurred in Northwest Sichuan, Southeast Xizang, the Qinghai-Xizang Plateau (Tibetan Plateau), Northern Xinjiang, Shanxi, Gansu, and Inner Mongolia. (2) The AOD over China varied with years from 2000 to 2017, which increased in the previous decade but gradually decreased from 2011. (3) The AOD changed more significantly with the seasons, with higher AOD in spring and summer, and lower in autumn and winter. (4) The AOD was negatively associated with Digital Elevation Model, with a Spearman correlation coefficient of −0.733, which was positively associated with Gross Domestic Product and Population Density, with Spearman correlation coefficients of 0.698 and 0.688. • Long-term variations and trends of AOD over china are studied. • High-value of AOD is basically located southeast of the Heihe-Tengchong Line. • The AOD in the desert regions of southern Xinjiang basin is lower than expected. • Both human activities and terrain have a significant impact on the AOD value. [ABSTRACT FROM AUTHOR]