Temporal-spatial Variation Characteristics Research Articles

Spatiotemporal Evolution and Prediction of AOT in Coal Resource Cities: A Case Study of Shanxi Province, China

As aerosols in the air have a great influence on the health of residents of coal resource-based cities, these municipalities are confronting the dilemma of air pollution that is caused by the increase of suspended particles in the atmosphere and their development process. Aerosol optical thickness could be used to explore the aerosol temporal and spatial variations and to develop accurate prediction models, which is of great significance to the control of air pollution in coal resource-based cities. This paper explored the temporal spatial variation characteristics of aerosols in coal resource-based regions. A total of 11 typical coal-resource prefecture-level cities in the Shanxi Province were studied and inverted the aerosol optical thickness (AOT) among these cities based on MODIS (Moderate Resolution Imaging Spectroradiometer) data and analyzed the significant factors affecting AOT. Through inputting significant correlation factors as the input variables of NARX (nonlinear auto regressive models with exogenous inputs) neural network, the monthly average AOTs in the Shanxi Province were predicted between 2011 and 2019. The results showed that, in terms of time series, AOT increased from January to July and decreased from July to December, the maximum AOT was 0.66 in summer and the minimum was 0.2 in autumn, and it was related to the local monsoon, temperature, and humidity. While as far as the space alignment is concerned, the figure for AOT in Shanxi Province varied significantly. High AOT was mainly concentrated in the centre and south and low AOT was focused on the northwestern part. Among the positively correlated factors, the correlation coefficient of population density and temperature exceeded 0.8, which was highly positive, and among the negatively correlated factors, the correlation coefficient of NDVI exceeded -0.8, which was highly negative. After improving the model by adding the important factors that were mentioned before, the error between the predicted mean value and the actual mean value was no more than 0.06. Considering this charge, the NARX neural network with multiple inputs can contribute to better prediction results.

Temporal-spatial variation characteristics of utilization efficiency of water resources in Changbai Mountain area

Temporal-spatial variation characteristics of utilization efficiency of water resources in Changbai Mountain area

Temporal-spatial variation and the affecting factors of protected areas in Guizhou, China.

The establishment of protected areas is the bottom line of ecological security for promoting the construction of ecological civilization and supporting economic and social development, which is an important strategy to realize sustainable development and maintain ecological security. In order to reveal the large spatial process of protected areas and its influencing factors, we used the methods of nearest neighbor index, kernel density, and standard deviational ellipse to analyze the temporal-spatial variation characteristics of the protected areas in Guizhou Province from 2002 to 2017, as well as the influencing factors combined with geo-detectors. The results showed that, during the study period, the number, area, and types of protected areas in Guizhou Province showed a diversified and rapid development, forming a protected area system with nature reserves, forest parks and scenic spots as the main body and wetland parks, geoparks and natural heritage sites as the supplement. The spatial cohesion of protected areas was strengthened, the scope of spatial distribution was expanding, and the speed of spatial movement was declining, forming a spatial pattern dominated by the northeast-southwest direction and gradually stable. The coalescence process in protected areas was strongly influenced by topography and vegetation distribution. The protected areas tended to cluster in gentle terrain around rivers and mountains and in areas of concentrated vegetation. The spatial differentiation of protected areas was jointly affected by multiple factors at different levels. The explanatory power of different factors to the spatial differentiation of protected areas was different. Among them, the normalized difference vegetation index, areas of forest and highway mileage were the common main factors affecting the spatial differentiation of the number and area of protected areas, and the explanatory power of different factors was significantly consolidated after interaction, characterized as nonlinear or bi-factor enhancement.

Analysis of Temporal-Spatial Variation Characteristics of Drought: A Case Study from Xinjiang, China

It is of great significance to study the characteristics and change trends of drought in Xinjiang to provide a basis for implementing local strategies. Based on monthly precipitation and temperature data from 95 meteorological stations in Xinjiang, from 1960 to 2018, the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated, and the characteristics and trends of drought in Xinjiang were analysed, in details. Furthermore, a comprehensive evaluation index, i.e., Regional Drought Severity (RDS), was proposed to analyse the effects of duration of the drought and the extent of the drought affected area. The results from our study suggested: (1) In consideration of global warming, droughts in Xinjiang have intensified during the past 59 years, and the frequency and range of droughts have increased significantly; (2) During the plant growing season, spring, summer, and autumn, a drying trend was observed, while, a wetting trend was identified for winter season; (3) The drought-prone months shifted from January and December to March-November in the 1970s, and April was identified as a month with the highest frequency of droughts; (4) The meteorological change occurred a period near 1997. It can be speculated that the intensified droughts can be triggered by the excessive temperature rise, through comparing the changes in SPEI and the Standardized Precipitation Index (SPI), before and after the meteorological change; (5) After the meteorological change, the frequency of droughts with different levels had significantly increased, in addition, the drought-prone areas shifted from the north-west to the south-east. The results from this research provide important support for drought management in Xinjiang, also offer scientific basis for the formulation of relevant policies on agricultural and animal husbandry production.

Temporal-spatial differences in and influencing factors of agricultural eco-efficiency in Shandong Province, China

ABSTRACT: Based on the panel data of 134 counties (cities and districts) from 1998 to 2017, the temporal-spatial variation characteristics and influencing factors of agricultural eco-efficiency in Shandong Province were analyzed by using various methods, such as the super-efficiency SBM (slacks-based measure) model considering undesired output and the STIRPAT (stochastic impacts by regression on population, affluence, and technology) model, which helps clarify the improvements needed for agricultural eco-efficiency and provides a basis for the development of ecological agriculture in Shandong Province. Results showed the following: (1) During 1998-2017, the agricultural eco-efficiency of Shandong Province showed a fluctuating increasing tendency, but the overall efficiency value wasrelatively low. (2) The agricultural eco-efficiency of Shandong Province had a significant regional disparity, and its spatial agglomeration gradually weakened. The spatial distribution had a sporadic distribution of high value areas at first and then gradually formed the “low-high-low-high” zonal distribution from west to east. (3) The net income per capita of farmers and the added value of the primary industry had a significantly positive correlation with the agricultural eco-efficiency of Shandong Province, while the mechanization level, the planting area per capita, the level of financial support to agriculture and the planting structure exhibited a mainly negative correlation with the agricultural eco-efficiency of Shandong Province. Moreover, the added value of the primary industry and the financial support to agriculture in the 0.75 quantile had no significant influence on the agricultural eco-efficiency of Shandong Province, and the planting structure in the 0.25 and 0.75 quantiles also had no significant influence.

Temporal-Spatial Variation Characteristics of Soil Erosion in the Pisha Sandstone Area, Loess Plateau, China

Temporal-Spatial Variation Characteristics of Soil Erosion in the Pisha Sandstone Area, Loess Plateau, China

Investigation and Analysis of All-Day Atmospheric Water Vapor Content over Xi’an Using Raman Lidar and Sunphotometer Measurements

All-day atmospheric water vapor content measurements determined by Raman lidar and a sunphotometer were combined to investigate the all-day variation characteristics in the water vapor distribution in Xi’an, China (34.233°N, 108.911°E). To enhance the daytime lidar performance, the wavelet threshold de-noising method is used to filter out the strong solar background light, and effective denoised results are demonstrated with the following optimization: wavelet sym6, the improved threshold function, and the improved threshold selection. The denoised system signal-to-noise ratio (SNR) for the water vapor daytime measurement is validated, with an enhancement of ~3.4 times up to a height of 3 km compared to that of the original signal. The time series of the atmospheric water vapor mixing ratio profiles and the obtained precipitable water vapor (PWV) measured by Raman lidar are used to reveal the temporal and spatial variations in water vapor, and the comparisons with the total column water vapor content (TCWV) measured by a sunphotometer validate the daytime variation trend of the water vapor. All-day continuous observations clearly present a consistent variation trend in the water vapor between the sunphotometer and Raman lidar measurements. The correlation analysis between TCWV and PWV at the layers below 850 hPa and below 700 hPa yields a good positive correlation coefficient (>0.75), indicating that PWV determination in the bottom layer by Raman lidar can directly reflect the variations in the total water vapor content. Moreover, different diurnal variation trends in water vapor are also observed, that is, a downward trend from the afternoon to the night, or a tendency of being high in the morning and afternoon and low at noon, demonstrating the high temporal-spatial variation characteristics of water vapor and close correlation with weather changes. The results reflected and validated that the diurnal variation in water vapor is complicated and can be an indicator of the weather to a certain extent.

Long-term characteristics of satellite-based PM2.5 over East China

With the explosive economic development of China over the past few decades, air pollution has become a serious environmental problem and has attracted increasing global concern. Using satellite-based PM2.5 data from 2000 to 2015, we found that the temporal-spatial variation of PM2.5 in East China is characterized by high concentrations in the northern part and low concentrations in the southern part of East China, and by being seasonally high in autumn and winter but low in spring and summer. We also found that the regional average PM2.5 concentration shows an approximative peak pattern over the last 16years, with the highest, 60.13μgm−3, and the lowest, 46.18μgm−3, occurring in 2007 and 2000, respectively. Despite obviously diminishing heavy polluted regions with a PM2.5 of >80μgm−3 after 2011, those cells dominated by natural background have still not recovered back to the clean level of 2000. These characteristics are valuable information to analyze the relative contributions of anthropogenic emissions and atmospheric conditions to the temporal-spatial variation characteristics of PM2.5.

中国南方干旱灾害风险特征及其防控对策

PDF HTML阅读 XML下载 导出引用 引用提醒 中国南方干旱灾害风险特征及其防控对策 DOI: 10.5846/stxb201608111644 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划（973计划）（2013CB430206）；公益性行业（气象）科研重大专项（GYHY201506001-6）；国家自然科学基金（41575149） Risk characteristics and control technology measures of drought disaster in Southern China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:应用中国南方区域14省区市252个国家基本气象站1961-2015年逐日地面气象观测资料及干旱灾害资料，研究中国南方干旱灾害影响的时空变化特征，分析中国南方干旱灾害风险变化特征，提出干旱灾害风险防控策略与防御对策。结果表明：近55年中国南方区域降水量呈现波动变化，降水量线性拟合趋势特征不明显。但进入21世纪后南方区域平均降水量明显偏少，且平均降水量年际振荡幅度增大。近55年研究区气温呈显著上升趋势，南方平均地表气温升高速率高于全球地表升温速率；研究区气温从1976年开始持续上升，气温升高的突变年在1997年。重旱风险高发区主要集中于西南，随着气候变暖，干旱灾害频率、强度和受旱面积均增加，干旱灾害风险增大。气温突变后次高干旱灾害风险区明显扩大。未来10年（2016-2025年）中国南方地区的干旱发生频率可能升高。因此，要加强干旱灾害风险管理，生态环境脆弱区域实施生态环境修复，农业主产区域以保障粮食安全为主，解决水资源时空分布不均和资源供需加剧矛盾，提高干旱灾害风险防控水平。 Abstract:Using daily surface meteorological observation and drought disaster data from 252 national basic meteorological stations located in 14 provinces in Southern China from 1961 to 2015, temporal-spatial variation characteristics of drought disaster influence and the risk change of drought disaster were studied. Based on these analyses, the control strategy and defense countermeasures for drought disaster risks are put forward. The results indicated that annual precipitation in Southern China fluctuated from 1961 to 2015 and no obvious linear trends. However, the average annual precipitation in Southern China is less than that in the period before 21st century, and its oscillation amplitude is increasing. The annual average temperature in the research region showed significant upward trend throughout 1961-2015, and the average surface temperature increasing rate was higher than that of the global average. The temperature has increased since 1976 in the research region, and a temperature mutation point occurred in 1997. Areas with higher risks of drought disaster include most regions in southwest China. With the global warming, the drought frequency and intensity and the drought affected areas have been increasing, as well as the risk of drought disaster. The risk area of secondary high drought disaster was significantly enlarged after the temperature mutation point in 1997. During the next 10 years (2016-2025), the drought disaster frequency in Southern China could increase. Therefore, the following management measures should be carried out: (1) drought disaster risk management should be strengthened; (2) areas with fragile ecological environment should be restored; (3) major agricultural production areas should be given priority for food production security; (4) the uneven temporal-spatial distribution of water resources and aggravating contradictions between supply and demand should be resolved; and (5) the level of drought disaster risk prevention and control should be improved. 参考文献 相似文献 引证文献

Temporal-Spatial Variation Characteristics of Acid Rain during 2007 to 2012 in Fujian Province

Based on the meteorological observation data of 4 acid rain monitoring stations (Shaowu Station, Fuzhou Station, Yong’an Station and Xiamen Station) during 2007 to 2012 in Fujian Province, the characteristics of the acid rain were analyzed. The results showed that acid rain pollution was common in Fujian Province while showing a reducing trend overall. The time from 2007 to 2010 was acid rain pollution period of large precipitation acidity and high strong acid rain frequency. And the time from 2011 to 2012 was acid rain improving period with precipitation acidity weakening and strong acid rain frequency declining. It showed an obviously seasonal feature for acid rain. Acid rain pollution was relatively heavy in winter while light in summer in Fuzhou, Shaowu and Xiamen. But the seasonal distribution in Yong’an was just the opposite. There were large differences in the degree of acid rain pollution in different regions. The acid rain pollution in Shaowu was heaviest belonging to the strong acid rain area. And the second was Fuzhou belonging to the moderate acid rain area. Xiamen and Yong’an belonged to the light acid rain area with lighter pollution. The acid rain pollution showed various degrees of improvements in Shaowu, Fuzhou and Xiamen. Especially in Fuzhou the improvement was particularly evident as the best condition in recent years. While in Yong’an the acid rain pollution had aggravated somewhat in recent years with the acid rain frequency increasing and the precipitation acidity enhancing.

Temporal and Spatial Variation in Regional Climate and its Impact on Runoff in Xinjiang, China

Based on the meteorological and surface runoff data from Xinjiang for the past 50 years, this study examined the temporal-spatial variation characteristics of the air temperature, precipitation and runoff in Xinjiang using nonparametric tests and wavelet analysis. The results indicate that the air temperature declined slightly in Kuche (KC). There were slight increasing trends in Bayinbluk (BYBLK), Alar (ALR) and Yutian (YT). The rest of the meteorological stations all had significant increasing trends. The precipitation showed significant increasing trends in the Altai Mountains, Alashankou (ALSK) and Jinghe (JH) in northern Xinjiang and a slight decreasing trend in Tuoli (TL). The other stations showed slight increasing trends. The annual rate of change of precipitation was greater in the northern mountain area than in the southern plains area. In the Tianshan Mountains, the decreasing trend of precipitation at BYBLK was not statistically significant, while the precipitation in the other stations increased to the high-precipitation areas from two low-precipitation centers, Zhaosu (ZS) and BYBLK. In the Tarim Basin of southern Xinjiang, the increasing trend and increasing rate of precipitation were more significant on the northern margin than they were on the southern margin. With regard to the surface runoff, significant uptrends appeared in Kenswat (KSWT), Dashankou (DSK), Shiliguilank (SLGLK), Xiehela (XHL) and Yzmeilek (YZMLK). Kaqun (KQ) and Wuluwat (WLWT) had slight increases, and Tongguzlek (TGZLK) showed a slight downtrend. The variations in air temperature and precipitation in Xinjiang had significant periods of 4–9 years and 3–10 years, respectively. The periods for the annual runoff were 5–9 years.

Analysis of temporal-spatial variation characteristics of extreme air temperature in Xinjiang, China

Abstract Based on data from 1961 to 2007, this paper discusses the variation trend and the periodic temporal-spatial patterns of the extreme air temperature in Xinjiang by means of the Mann-Kendall monotonous trend test and wavelet analysis. The results are as follows: (1) In the north, south and east of Xinjiang, the annual average maximum air temperature, annual average minimum air temperature and annual minimum air temperature all rose remarkably, while the rise of the annual maximum air temperature was not significant. (2) The rising trend of the annual average maximum air temperature was stronger in the east than in the north, and it was weakest in the south. The rising trend of annual average minimum air temperature was strongest in the east, followed by the south and the north. The annual maximum air temperature rose more strongly in the south than in the north, and the rise was weakest in the east. The change in annual minimum air temperature was higher in the south than in the east and was lowest in the north. (3) The mean values of annual average maximum temperature, annual average minimum temperature, and annual minimum temperature were highest in the south, followed by the east and north. The mean value of annual maximum temperature was highest in the east, followed by the north, and it was the lowest in the south. (4) Significant periodic variations with periods of 3–11 years appeared in the extreme air temperatures. (5) Wavelet coefficients can predict well the variation trend of extreme temperature in the future based on a significant period. These results can be applied in early warning of meteorological disasters and in realizing sustainable agricultural development in the study area.

MULTI-TEMPORAL DYNAMIC CHANGE OF THE LAKE WATER AREA IN ANQING ALONG THE YANGTZE RIVER IN THE PAST TWENTY YEARS

Different periods of remote sensing image data were processed on the basis of GIS and remote sensing technology and,as a result,data concerning five periods of water areas of eight main lakes along the Yangtze River were obtained.Based on an analysis of their temporal-spatial variation characteristics in combination with related data and field investigation,this paper has summed up the causes for the change of water areas and dealt with the countermeasures for rational utilization and protection of lake water resources.