Zhao zhao Jun

Prof. Dr. Zhao zhao Jun

orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 August 2018 in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Verified
Journal Article
Closed access
SBShanhu Bao
Shanhu Bao
LHLetu Husi
Letu Husi
Chuanfeng ZhaoChuanfeng Zhao
Chuanfeng Zhao
GTGegen Tana
Gegen Tana
HSHuazhe Shang
Huazhe Shang
ZJZhao zhao Jun
Zhao zhao Jun
The Mongolian Plateau (MP) has important influences on regional and global climate change. The spatiotemporal variations in the cloud cover and cloud optical thickness of total, high, middle, and low clouds over the MP during the daytime from 2006 to 2015 are analyzed using MODIS level 2 atmospheric data. Results show that the annual average total cloud cover over the MP decreases from the forest area in the northeast to the desert area in the southwest. The total cloud cover over the MP is obviously higher in summer than in other seasons, in which high clouds have a largest proportion, with the substantial total cloud cover changes. The spatial distributions of the high, middle, and low cloud covers over the MP are highly variable. The cooling effect of the cloud net radiative forcing is greater during the daytime in summer than in other seasons, which is likely associated with thick cloud optical thickness or large cloud cover in summer. Combined with the analyses of relationships among cloud cover, cloud optical thickness, cloud radiative forcing, and air temperature, the results show that significantly negative correlations exist between cloud optical thickness and cloud radiative forcing, and between total cloud cover and air temperature in the MP. The decrease in air temperature in summer over the MP during daytime confirm that the increase in the daytime total cloud cover strengthen the cooling effects of clouds and decrease the air temperature, especially in the high-value area with cloud cover distribution over the northeast MP.

12 March 2021 in Remote Sensing
Verified
Journal Article
Open access
PDF file
XYXiaoying Yue
Xiaoying Yue
ZLZhong Qin Li
Zhong Qin Li
ZJZhao zhao Jun
Zhao zhao Jun
HLHuilin Li
Huilin Li
PWPuyu Wang
Puyu Wang
LWLin Wang
Lin Wang
For summer-accumulation-type glaciers, the glaciological literature is lacking studies on determining the snow line altitude (SLA) from optical images at the end of the summer as an indicator of the equilibrium line altitude (ELA). This paper presents a workflow for extracting the SLA from Landsat images based on the variation in the albedo with the altitude in the central line area of glaciers. The correlation of >0.8 at the 99% confidence level between the retrieved SLAs with ELAs derived from the interpolation of ground-based, mass balance measurements indicated that the workflow can be applied to derive the SLA from end-of-summer satellite data as an indicator of ELA. The ELA was under-estimated by the calculated SLA. The relationship between the end-of-summer SLA and the ELA depends on the intensity of glacier melting. Subsequently, the workflow was applied to the seven glaciers in the Eastern Tien Shan Mountains, and a time series of the SLA was obtained using 12 end-of-summer Landsat scenes from 1994 to 2016. Over the whole study period, a mean SLA of 4011.6 ± 20.7 m above sea level (a.s.l.) was derived for the seven investigated glaciers, and an increasing SLA was demonstrated. The increase in SLAs was consistent for the seven glaciers from 1994 to 2016. Concerning the spatial variability, the east–west difference was prominent, and these differences exhibited a decreasing trend. The average SLA of each glacier is more influenced by its morpho-topographic variables. The interannual variations in the average SLA are mainly driven by the increasing summer air temperature, and the high correlation with the cumulative summer solid precipitation reflects the characteristics of the summer-accumulation-type glaciers.

16 November 2021 in Sustainability
Verified
Journal Article
Open access
PDF file
ZYZhihui Yang
Zhihui Yang
ZJZhao zhao Jun
Zhao zhao Jun
JLJialiang Liu
Jialiang Liu
YWYuanyuan Wen
Yuanyuan Wen
YWYanqiang Wang
Yanqiang Wang
Soil moisture plays an important role in the land surface model. In this paper, a method of using VV polarization Sentinel-1 SAR and Landsat optical data to retrieve soil moisture data was proposed by combining the water cloud model (WCM) and the deep belief network (DBN). Since the simple combination of training data in the neural network cannot effectively improve the accuracy of the soil moisture inversion results, a WCM physical model was used to eliminate the effect of vegetation cover on the ground backscatter, in order to obtain the bare soil backscatter coefficient. This improved the correlation of ground soil backscatter characteristics with soil moisture. A DBN soil moisture inversion model based on the bare soil backscatter coefficients as the foundation training data combined with radar incidence angle and terrain factors obtained good inversion results. Studies in the Naqu area of the Tibetan Plateau showed that vegetation cover had a significant effect on the soil moisture, and the goodness of fit (R2) between the backscatter coefficient and soil moisture before and after the elimination of vegetation cover was 0.38 and 0.50, respectively. The correlation between the backscatter coefficient and the soil moisture was improved after eliminating the vegetation cover. The inversion results of the DBN soil moisture model were further improved through iterative parameters. The model prediction reached its highest level of accuracy when the restricted Boltzmann machine (RBM) was set to seven layers, the bias and R were 0.007 and 0.88, respectively. Ten-fold cross-validation showed that the DBN soil moisture model performed stably with different data. The prediction was further improved when the bare soil backscatter coefficient was used as the training data. The mean values of the root mean square error (RMSE), the inequality coefficient (TIC), and the mean absolute percent error (MAPE) were 0.023, 0.09, and 11.13, respectively.

13 March 2020 in Remote Sensing
Verified
Journal Article
Open access
PDF file
YZYanli Zhang
Yanli Zhang
XQXiang Qin
Xiang Qin
XLXin Li
Xin Li
ZJZhao zhao Jun
Zhao zhao Jun
LYLiu Yushuo
Liu Yushuo
Downward surface shortwave radiation (DSSR) is the main energy source for most glacial melting, and Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat Thematic Mapper (TM) data have been used extensively in the inversion of input parameters for estimating DSSR. However, for valley glaciers under complex climatic conditions, the values of MODIS atmospheric products, especially aerosol products, are often invalid, and TM images are always saturated with snow. Furthermore, an estimation model based on optical satellite images must simultaneously consider terrain and atmospheric effects and the transient nature of ice/snow albedo. Based on a high-resolution (12 m) digital elevation model (DEM), the newly launched Sentinel-2 satellites, rather than MODIS and TM, were used to provide input data for our published mountain radiation scheme in a valley glacier. Considering Laohugou Glacier No. 12 as the study area, 62 typical Sentinel-2 scenes were selected and spatiotemporal DSSR variations on the glacier surface were obtained with a 10 m spatial resolution during a mass-balance year from September 2017 to August 2018. Ground-based measurements on 52 clear-sky days were used for validation and the mean bias error (MBE = −16.0 W/m2) and root-mean-square difference (RMSD = 73.6 W/m2) were relatively low. The results confirm that DSSR is affected mainly by the solar zenith angle and atmospheric attenuation in flat areas of valley glaciers, while in areas with complex terrain, the DSSR received by the glacier surface is affected primarily by the terrain and ice/snow albedo, which exhibits very high spatial heterogeneity.

24 October 2024 in Sustainability
Verified
Journal Article
Open access
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YFYixuan Fu
Yixuan Fu
ZJZhao zhao Jun
Zhao zhao Jun
Ecotourism, which promotes environmental conservation and brings social and economic benefits through conscious and harmonious interactions between humans and nature, has become a principal tool for achieving these objectives. Sustainable tourism can only be supported with tourists realizing the elements of attraction toward ecotourism. This study analyzes the roots of ecotourism behavior using the Theory of Planned Behavior (TPB), specifically determining the roles of ecotourism tendency, attitude, human–land coordination stress, and sense of self-control in influencing tourists’ intention and behavior toward ecotourism. This study used a cross-sectional design, requiring 847 participants to complete a standardized questionnaire assessing their behavior toward ecotourism, attitudes, and perceptions. Reliability testing, descriptive statistics, regression analysis, and factor analysis were used to analyze the datasets to discover major factors relating to ecotourism intention behavior. A consequent outcome is that ecotourism attitude and self-determination are the significant drivers of ecotourism desire, while behavioral norms only impact ecotourism attitude and selflessness. The study concluded that the subjective perception of tourists and their behavior control ability are the ones that affect their ecotourism behavior more than other factors. The findings suggest that enhancing tourists’ ecotourism attitude, sense of self-control, and awareness of human–place coordination can significantly promote ecotourism behaviors. These results highlight the importance of comprehensive regional ecotourism analysis, robust environmental education, and promoting normative behaviors to foster sustainable tourism practices. To validate these findings, further research should focus on longitudinal studies and clinical trials to standardize integrated ecotourism strategies and explore the underlying mechanisms influencing ecotourism behavior.

19 August 2022 in Sustainability
Verified
Journal Article
Open access
PDF file
JYJIanxia Yang
JIanxia Yang
ZJZhao zhao Jun
Zhao zhao Jun
GZGuofeng Zhu
Guofeng Zhu
YWYuanyuan Wen
Yuanyuan Wen
YWYanqiang Wang
Yanqiang Wang
ZYZhihui Yang
Zhihui Yang
(1) Background: Recently, secondary soil salinization has frequently occurred in ecological water conveyance and irrigation areas. Therefore, monitoring the information on soil salinization in the conveyance irrigation area and analyzing the change process of soil salinization are of great significance to both environmental improvement and salinization management. (2) Methods: This study takes the Shiyang River’s terminal lake—Qingtu Lake—and its surroundings as the research area. The salinization index was extracted by remote sensing data and methods, and a comprehensive salinization model (CSI) was established. Firstly, the spatial distribution regular of soil salinization, since ecological water conveyance was explored, and the change trends in soil salinization were analyzed. Secondly, the relationship between the change characteristics of soil salinization and groundwater, water area changes and land use types were analyzed. (3) Results: The Kappa coefficient between the soil salinization extracted by CSI and the measured data reached 0.703, and CSI can accurately monitor soil salinization information. From 2011 to 2020, the non-salinized land increased by 2.1%, mild and moderate salinization decreased by 5.7% and 3.9%, respectively, and severe salinization increased by 7.5%. The salinization in the lake area showed a decreasing trend, and the periphery of the lake area showed an increasing trend. Groundwater, water area changes and land use type have certain influences on soil salinization in the study area. (4) Conclusion: Since ecological water conveyance, the total proportion of soil salinized area in Qingtu Lake and its surrounding areas has not changed much, but there are certain changes between different grades of salinized land. The areas with changes to the level of salinization are mainly shallow, unstable water areas, saline–alkali land, wetlands and sandy land, and there are secondary salinization problems in these areas.