Changes In Temperature Characteristics Research Articles

The Evaluation of Temporal and Spatial Trends of Global Warming and Extreme Ocean Surface Temperatures: A Case Study of Canada

In recent years, extreme weather has frequently occurred worldwide and caused significant disasters, including large-scale forest fires, rare heat waves, heavy rains, floods, and tornadoes. Those have caused unprecedented losses of human lives and property in some countries, affecting the livelihoods of many people. Climate change and natural disasters are the two hotspots of scientific research today, and there is a certain degree of correlation between the two. Although countries worldwide have long known about climate change and its threats to human existence and have been discussing countermeasures, they have still not been able to carry out concerted and practical actions. The study takes Canada as an example, and selects six representative provinces to evaluate the temporal change characteristics of extreme temperature at different sites. We use MATLAB software to perform multiple linear regression, linear fitting methods, and Pearson correlation analysis to analyze spatial changes and time-space trends. The method studies the relationship between the emergence of extreme weather and climate change and uses the evolutionary game theory to explore whether there is any contradiction between global warming and extreme local cold. The study found: (i) The maximum temperature of most provinces in Canada will be constantly higher, and the minimum temperature will be lower. Generally speaking, the average temperature of each year is slowly decreasing. (ii) The average temperature data of British Columbia (Eastern Pacific) and Quebec (West Atlantic) show that ocean temperature has a specific effect on land temperature in surrounding areas. (iii) Pearson correlation analysis shows that the emergence of extreme weather is closely related to climate change. (iv) The evolution path of the two-party game shows that global warming and the occurrence of extreme local cold are not contradictory. Under the conditions, there is a certain degree of synchronization between the two, interacting and influencing each other.

A Supplementary Module to Improve Accuracy of the Quality Assessment Band in Landsat Cloud Images

Cloud contamination is a serious obstacle for the application of Landsat data. To popularize the applications of Landsat data, each Landsat image includes the corresponding Quality Assessment (QA) band, in which cloud and cloud shadow pixels have been flagged. However, previous studies suggested that Landsat QA band still needs to be modified to fulfill the requirement of Landsat data applications. In this study, we developed a Supplementary Module to improve the original QA band (called QA_SM). On one hand, QA_SM extracts spectral and geometrical features in the target Landsat cloud image from the original QA band. On the other, QA_SM incorporates the temporal change characteristics of clouds and cloud shadows between the target and reference images. We tested the new method at four local sites with different land covers and the Landsat-8 cloud cover validation dataset (“L8_Biome”). The experimental results show that QA_SM performs better than the original QA band and the multi-temporal method ATSA (Automatic Time-Series Analyses). QA_SM decreases omission errors of clouds and shadows in the original QA band effectively but meanwhile does not increase commission errors. Besides, the better performance of QA_SM is less affected by the selections of reference images because QA_SM considers the temporal change of land surface reflectance that is not caused by cloud contamination. By further designing a quantitative assessment experiment, we found that the QA band generated by QA_SM improves cloud-removal performance on Landsat cloud images, suggesting the benefits of the new method to advance the applications of Landsat data.

Assessment of the value of ecosystem services in water sources of the South-North Water Diversion Central Project: the case of Dengzhou City, Henan Province

Dengzhou City is the first ecological water recharge city after the commissioning of the South-North Water Diversion Project. A study on the ecological service value of Dengzhou City and its evolutionary characteristics can provide a theoretical basis for the water supply security of the Central Line Project and regional ecological environmental protection. Based on the ecosystem service value equivalent factor method, GIS, ENVI and GeoSOS-FLUS software were used to monetize the ecosystem service values of Dengzhou City in 2007, 2011, 2014, 2015 and 2020; analyze the spatial and temporal change characteristics under its land use change conditions and predict the regional ecosystem service values of Dengzhou City in 2025. The results show that since the completion and commissioning of the South-North Water Transfer Central Project in 2014, the value of ecosystem services in Dengzhou City has rapidly increased from US$3.792 billion to US$4.612 billion, and in 2025, the value of ecosystem services in Dengzhou City is expected to reach US$4.8 billion.

Changes in permafrost extent and active layer thickness in the Northern Hemisphere from 1969 to 2018

Understanding the evolutions of the permafrost extent and active layer thickness (ALT) in the Northern Hemisphere (NH) are critical for global carbon flux simulation, climate change prediction, and engineering risk assessment. The temporal change characteristics of the permafrost extent and ALT for the NH have not been studied. We used the Kudryavtsev method, integrating a 0.5° × 0.5° spatial resolution of air temperature, soil texture, snow depth, vegetation type, soil volume moisture content, and organic content to simulate the changes of permafrost extent and ALT in the NH from 1969 to 2018. The results indicated that permafrost extent decreased from 23.25 × 106 km2 (average from 1969 to 1973) to 21.64 × 106 km2 (average from 2014 to 2018), with a linear rate of −0.023 × 106 km2/a. Siberia had the highest degradation rate of 0.014 × 106 km2/a, followed by Alaska, Mongolian Plateau, Qinghai-Tibet Plateau, Northern Canada, and Greenland, with linear rates of −0.012 × 106, −0.005 × 106, −0.004 × 106, −0.0014 × 106, and − 0.0004× 106 km2/a, respectively. The average ALT in the NH increased at a linear rate of 0.0086 m/a. Alaska and Mongolian Plateau had the highest thickening rate of 0.024 m/a, followed by Qinghai-Tibet Plateau, Siberia, Northern Canada, and Greenland, which had linear rates of 0.009, 0.008, 0.0072, and 0.003 m/a, respectively. The uncertainty of the results could be attributed to the inaccurate forcing data and limitations of the Kudryavtsev model.

Durağan-Durum Görsel Uyarılmış Potansiyellere Dayalı Beyin-Bilgisayar Arayüzünün Zamansal ve Frekanssal Derinliğinden Frekans Tanıma

Brain-computer interface (BCI) system based on steady-state visual evoked potentials (SSVEP) have been acceleratingly used in different application areas from entertainment to rehabilitation, like clinical neuroscience, cognitive, and use of engineering researches. Of various electroencephalography paradigms, SSVEP-based BCI systems enable apoplectic people to communicate with outside world easily, due to their simple system structure, short or no training time, high temporal resolution, high information transfer rate, and affordable by comparing to other methods. SSVEP-based BCIs use multiple visual stimuli flickering at different frequencies to generate distinct commands. In this paper, we compared the classifier performances of combinations of binary commands flickering at seven different frequencies to determine which frequency pair gives the highest performance using temporal and spectral methods. For SSVEP frequency recognition, in total 25 temporal change characteristics of the signals and 15 frequency-based feature vectors extracted from the SSVEP signal. These feature vectors were applied to the input of seven well-known machine learning algorithms (Decision Tree, Discriminant Analysis, Logistic Regression, Naive Bayes, Support Vector Machines, Nearest Neighbour, and Ensemble Learning). In conclusion, we achieved 100% accuracy in 7.5 - 10 frequency pairs among these 2,520 distinct runs and we found that the most successful classifier is the Ensemble Learning classifier. The combination of these methods leads to an appropriate detailed and comparative analysis that represents the robustness and effectiveness of classical approaches.

Towards quantification of the national water footprint in rice production of China: A first assessment from the perspectives of single-double rice

Rice is one of the most important crops in China, contributing to approximately 28% of total cereal yield. Despite substantial production, given that rice is a high water-consuming crop, the water shortage due to the irreversible decline in available water resources on a global scale induced by undergoing climate change will pose grave challenges to rice reproductive growth and related water resources utilization. As a consequence, investigating the responses of rice productivity and water consumption to more pronounced climate changes is of great significance for water resources sustainable utilization in terms of reducing irrigation water requirements and ensuring food security. Present water footprint (WF) methods do not calculate the weighted average of each WF component at the national level when evaluating the effects of prospective climate change upon rice production. The national water footprint (NWF), i.e. taking the share of each province in the total production of crops as weighting factors, has been regarded as an effective approach to determine where each WF component is originally located. In this study, the temporal change characteristics of NWF for single-rice (SR), early-rice (ER) and late-rice (LR) in different agro-ecological zones across China during 2001–2010 were assessed for the first time. The results exhibited that NWF of rice was an estimated 304,848 million cubic meters (MCM) per year. The SR accounted for the greatest portion of NWF, followed by ER and LR. The NWF rank was SR-V > SR-I > ER-VI > SR-IV > LR-III > LR-VI > SR-II > ER-III. The blue water footprint (WFb) presents decreasing trends in most agro-ecological zones (SR-I, SR-II, SR-IV, ER-III and LR-VI), while green water footprint (WFg) exhibits increasing trends within these regions. This study provides a beneficial approach for decision-making processes aiming at better agricultural water resources management strategies to alleviate water resources scarcity and reduce food risk in the context of surging demand, which will support agricultural water resources management of China towards a more balanced direction at the national level.

Spatio-temporal evolution and influencing factors of water resource carrying capacity in Shiyang River Basin: based on the geographical detector method

Abstract In this article, the comprehensive evaluation of water resource carrying capacity (for short WRCC) in Shiyang River Basin is the objective. Based on the comprehensive evaluation model of regional WRCC, the spatial and temporal change characteristics of the WRCC in Shiyang River Basin in 2007, 2011 and 2016 have been analyzed. Moreover, the influence elements of water resource carrying capacity in Shiyang River Basin are detected by the geographical detector. The results show that: (1) In terms of the spatial dimension, water resources in Shiyang River Basin are not in accordance with the distribution of social and economic development and population distribution, presenting a prominent contradiction between supply and demand of water resources; (2) in terms of the temporal dimension, the pressure on water resources in Shiyang River Basin has gradually increased, and the area of overload, light overload and serious overload has been augmented; (3) the geographical detector indicates that the influences of the water resources system and coordinating system factors are declining, and the influences of the social economy system and ecological factor are obviously increasing. The influences of the interaction with any two factors are stronger than that of a single factor, and the synergistic influences of two factors are aggravated.

西南地区主要农业气象灾害时空变化特征及趋势分析

西南地区主要农业气象灾害时空变化特征及趋势分析

Spatial–Temporal Analysis of Urban Land-Use Efficiency: An Analytical Framework in Terms of Economic Transition and Spatiality

Rapid urban expansion may cause a decline in land-use efficiency and result in a series of social and ecological problems. Economic transition has significantly influenced urban land development, and provides a good perspective for analyzing changes in land-use efficiency. This paper primarily discusses the theoretical influence of economic transition on urban land-use efficiency. Using 126 cities in the Yangtze River Economic Zone as examples, we explore the spatial–temporal characteristics of changes in land-use efficiency, and estimate the relationship between land-use efficiency and economic transition with econometric models. The results show that the land-use efficiency of the Yangtze River Economic Zone has generally been improved over time, and presented significant clustering effects around urban agglomerations. Panel data analysis suggests that foreign direct investment in the globalization process and tax burdens, which were further aggravated by the reform of the responsibility and revenue assignment between local and central government, have had a significant negative effect on land-use efficiency. On the contrary, marketization, urbanization, and fiscal expenditure decentralization have exerted significant positive effects. We also found that agglomeration effects and location advantages did play a positive role in improving land-use efficiency, which accounted for the spatial inequality. This paper concludes with policy proposals to improve the intensification and economization level of urban land use.

A review of past and projected changes in Australia's rainfall

There has been much attention given to the spatial and temporal characteristics of changes in mean and extreme rainfall over Australia during the past century. As Australia is the second driest continent on Earth, reliable projections around the trends and variability in future rainfall are crucial for policymakers and water resource management. This article comprehensively reviews the current published literature on trends in Australia's rainfall from pre‐instrumental and instrumental records, the climatic drivers of Australia's rainfall variability, attribution of the long‐term trends, extreme rainfall attribution methods with particular reference to a recent case study (2010–2012 east Australia rainfall event) and projected changes of mean and extreme rainfall over Australia during the 21st century. Notable trends in the observational record of rainfall in Australia are a decrease in mean rainfall in southwest and southeast Australia and an increase in northwest Australia since 1950. The general consensus of research into Australia's future rainfall is that mean rainfall will continue to decrease in southwest Australia in a warming world, while changes over northern and eastern Australia remain uncertain. There are still significant knowledge gaps around the causes of observed trends in rainfall both in the mean and extremes, the ability of climate models to accurately represent rainfall in the Australian region and future rainfall projections. These gaps are identified, and avenues for future research directions are proposed.This article is categorized under: Paleoclimates and Current Trends > Modern Climate Change

Identification and mapping of winter wheat by integrating temporal change information and Kullback–Leibler divergence

Crop acreage and its spatial distribution are a base for agriculture related works. Current research combining medium and low spatial resolution images focuses on data fusion and unmixing methods. The purpose of the former is to generate synthetic fine spatial resolution data instead of directly solving the problem. In the latter, high-resolution data is only used to provide endmembers and the result is usually an abundance map rather than the true spatial distribution data. To solve this problem, this paper designs a conceptual model which divides the study area into different types of pixels at a MODIS 250 m scale. Only three types of pixels contain winter wheat, i.e., pure winter wheat pixels (PA), the mixed pixels comprising winter wheat and other vegetation (MA) and the mixed pixels comprising winter wheat and other crops (MB). Different strategies are used in processing them. (1) Within the pure cultivated land pixels, the Kullback–Leibler (KL) divergence is employed to analyze the similarity between unknown pixels and the pure winter wheat samples on the temporal change characteristics of NDVI. Further PA is identified. (2) For MA, a proposed reverse unmixing method is firstly used to extract the temporal change information of cultivated land components, after which winter wheat is identified from the cultivated land components as previously described. (3) For MB which only appears on the border of PA, a mask is created by expanding the PA and temporal difference is utilized to identify winter wheat under the mask. Finally, these three results are integrated at a TM scale with the aid of 25 m resolution land use data. We applied the proposed solution and obtained a good result in the main agricultural area of the Yiluo River Basin. The identified winter wheat planting acreage is 161,050.00 hm2. The result is validated based on the five-hundred random validation points. Overall accuracy is 94.80% and Kappa coefficient is 0.85. This demonstrates that the temporal information reflecting crop growth is also an important indicator, and the KL divergence makes it more convenient in identifying winter wheat. This research provided a new perspective for the combination of low and medium spatial resolution remote sensing images. The proposed solution can also be effectively applied in other places and countries for the crop which has a clear temporal change characteristic that is different from others.

RETRACTED ARTICLE: Study on the spatial–temporal change characteristics and influence factors of fog and haze pollution based on GAM

PM2.5 (particulate matter) is an important object for air quality monitoring, and the research on related influence factors and diffusion process of PM2.5 plays a key role in the fight against pollution of fog and haze. Based on the air quality monitoring data and related meteorological data of 16 districts of Beijing during November 2016 and December 2017, such methods as time-series analysis and nonparametric test are adopted to describe the variation trend of PM2.5 concentration in space and time and its disparities in different seasons, time periods and areas. Linear regression method is used in most of the previous research on influence factors and prediction of PM2.5 concentration, but actually, the relation between these factors is rather intricate and it is usually nonlinear. So, generalized additive model (GAM) is used in this paper to analyze the impact that different influence factors, especially their interaction, have on PM2.5 concentration and its diffusion process. The result shows that in the dimensionality of time, PM2.5 concentration has strong autocorrelation over time and it is most significant in the first to the third order (lag 0–lag 3). Throughout the year, PM2.5 concentration is relatively high in winter and low in summer. It is usually the lowest during 16:00–18:00 and the highest during 9:00–11:00 every day and far higher at night than in the daytime (MD = − 6.455, P = 0.003). And in terms of space, PM2.5 concentration shows distinct spatial gradient and it gradually decreases from south to north (MD = − 19.250, P = 0.004). It is found in the analysis of influence factors of PM2.5 concentration that the change of PM2.5 concentration is a complex nonlinear time series driven and affected by many factors; among these factors, the interaction between air pollutants and meteorological elements is the most prominent, while average wind speed (WS lag 1) plays a decisive role in the entire diffusion process, and it explains the whole diffusion of PM2.5 concentration to a large extent.

Evolution of technology convergence networks in Korea: Characteristics of temporal changes in R&D according to institution type.

This study investigates the temporal changes in development of technology convergence networks by institution type, i.e., public research institute (PRI), university and industry. Using the co-classification of technological domains of patents, we identified technology convergence of Korean patents, which were filed at Korea Intellectual Properties Office (KIPO) from 1997 to 2011. We conducted a network analysis at the technology level to search for the key technology fields and frequent instances of technology convergence. The results show that technology convergence networks have grown significantly in the recent period regardless of the institution type. While industries started to conspicuously engage in technology convergence in the late 1990s, universities or PRIs did not do so until the mid-2000s. This discrepancy in the phase of technology convergence is attributed to the temporal difference in R&D stage (e.g., basic research and commercial product development). Our findings imply that corporal and governmental R&D management decision on promising technology fields will be more effective if the decision makers carefully consider the type of R&D entity in analyzing technological landscapes.

Rural settlements transition (RST) in a suburban area of metropolis: Internal structure perspectives

Rural settlements transition (RST) is one of the most significant indices for understanding the phenomena of rural reconstruction and urban-rural transformation in China. However, a systematic overview of RST is missing, and there is a lack of evidence regarding its characteristics from the internal structure perspectives. In this paper, we systematically explore the RST regarding spatio-temporal change characteristics of internal structure, patterns and impacts on rural environment and development by using practical survey internal land-use data from 2005 to 2015. The results show that the temporal change characteristics of the internal structure of rural settlements demonstrate a tendency for housing land to decrease and other land-use types to increase. The spatial change characteristics reveal that the structure inclines to more complexity and diversity from an exurban area to an urban-rural fringe area. Based on this finding, we identify that rapid development of rural industrialization, more agglomerate and effective industrial land-use, and improved public infrastructure construction are the general RST patterns. Spatially, there exists a physical decay pattern in the exurban area, thereby resulting in the hollowing-out of rural industries and of the population. In addition, the extensive and disorderly pattern in the suburban area causes low efficiency output and serious environmental pollution. The RST pattern in the urban hinterland promoted the “men-environment” compatible development. The study concludes that regional differentiation in patterns and impacts are significant in the process of RST. Future adaptive strategies for rural settlements adjustment should be conducted according to regional characteristics, including socio-economic status, physical geography condition and economic location to improve the rural environmental sustainability.

Characteristics of temporal changes in communities where dynamics differ between species

Communities with different phenotypic variation among species can have identical species abundance distributions, although their temporal dynamics may be very different. By using stochastic species abundance models, both the lognormal and beta prime abundance distributions can be obtained with either homogeneous or heterogeneous dynamics among species. Assuming that anthropogenic activity disturbs the communities such that species’ carrying capacities are decreasing deterministically, the structure of the communities are studied using simulations. In order to construct homogeneous communities with reasonable variation in abundance, the parameter values describing the dynamics of the species can be unrealistic in terms of long return times to equilibrium. Species in heterogeneous communities can have stronger density regulation, while maintaining the same variation in abundance, by assuming heterogeneity in one of the dynamical parameters. The heterogeneity generates variation in carrying capacity among species, while reducing the temporal stochasticity. If carrying capacity decreases, changes in community structure occur at a much slower rate for the homogeneous compared to the heterogeneous communities. Even over short time periods, the difference in response to deterministic changes in carrying capacity between homogeneous and heterogeneous community models can be substantial, making the heterogeneous model a recommended starting point for community analysis.

Numerical investigations on two-phase flow modes in evaporative condensers

Falling film evaporation over horizontal tubes consists of simultaneous heat and mass transfer processes: in an evaporative condenser it improves the heat rejection from the condensing refrigerant to the air. The liquid flow is generally influenced by viscous, gravity, tension effects, liquid mass flow rate, tube diameter and spacing and distance from the feeding system.In this work, a two-dimensional numerical model of the falling film evaporation on horizontal tubes is presented. The temporal change characteristics of the film flow process were studied and different types of flow (stable film and drops mode) were investigated, by varying the ratio between the water-to-air mass flow ratio.The effect of the tubes arrangement on the flow mode was analyzed too: an increase of 73% of the longitudinal pitch corresponds to an increase of 66.7% of the minimum water mass flow rate that prevents the film break-up. The trade-off curve for a given geometry was obtained: at a specific air mass flow rate, a transition zone between the stable film to the drops mode conditions was individuated, with an uncertainty of 10% referring to a water mass flow rate variation of 10%.

DEGRADATION OF THREE–JUNCTION AMORPHOUS SI : H BASED SOLAR CELLS

The operating experience of hydrogenated amorphous silicon (a−Si : H) based solar cells has shown that besides their low efficiency this type of photovoltaics degrade much faster compared to single crystal based solar cells. As far as the processes deter- mining the degradation of amorphous materials based solar cells are not well studied, and the degradation of similar cells without light exposure has also been reported, we conducted an experiment to compare the temporal change characteristics of main solar cell parameters in darkness and under natural light. The demonstration of short circuit current reduction in darkness aged solar cells should be considered as one of the most interesting results of the work. Moreover we have shown that the change of this parameter is on average the same for the illuminated cells, while for some cells short circuit current reduction is substantially higher. This is indicative of the fact that the observed effect is not related to the Staebler—Wronski effect.

Change of cropland in typical area of Middle-Lower Yangtze Plain over the past 30 years

In order to analyze the spatial- temporal change characteristics of the cropland in typical areas of Middle-Lower Yangtze Plains from 1984 to 2010,the authors extracted the land cover information of the study area in1984,1990,1995,2000,2005 and 2010 from Landsat TM /ETM+images. The results show that the amount of cropland decreased over the past 30 years. There were three stages of the cropland change: Fast reduction,slow reduction,and sharp reduction. The total area of cropland loss was 374. 10 km2from 1984 to 1990. The decrease of cropland was 66. 09 km2from 1990 to 2000,and the loss speed was relatively slow. The cropland in the study area was reduced rapidly to 1 724. 33 km2from 2000 to 2010. Most of the lost cropland was transformed into the construction land,and the cropland in cities along the Yangtze River,such as Nanjing,Maanshan,and Wuhu,was decreased more seriously than that in counties. The speed of urbanization was accelerated. Moreover,plenty of cropland was turned into ponds to breed fish and crabs around the Shijiu Lake and the Gucheng Lake,particularly in western regions where the conversion was prominently frequent from 1990. On the other hand,cropland was increased along the boundary of cropland and mountain from 1984 to 2000. After that,the cropland decreased because of the implementation of returning cropland to forest and creating economic forest.

Environmental Effects of Soil Salt in the Arid Area under the Human Beings' Interference

This paper mainly discussed the relations about the environmental effects of soil salt in the arid area in the west China,especially under the human being activity.Based on soil sampling and chemical analysis,some features are fund out. From the beginning of soil physical and chemical properties,the spacial distribution features and temporal change characteristics of soil salt are pointed out. Furthormore,the complexity of environmental effects of soil salt are revealed in a sense.In order to improve environmental quality,human beings should pay attention to the coupling between water and soil as well as the water resource,vegetation resource and land resource management in the arid area.

Spatiotemporal Variation of Wind Erosion Climatic Factor in Shandong Province

With Mann-Kendall non-parametric test and spatial interpolation methods, the research has explored the spatial and temporal characteristics of changes of wind erosion climatic factor C within 58 years in Shandong province. The annual average C value of the province is 163.57 with the peak value occurred both in Yantai, Weihai cities and the central area. The Yellow River flood plain, which is the most serious wind erosion district, only lies between 50 ~200. The average C value has shown a significant downward trend in the entire province for 58 years, and the peak occurred in 1962 and valley value occurred in 1990. The C value has shown a downward trend in most area of the province, among which the decrease of areas centered on Ji’ning is the greatest and reach -7/a. On the Yellow River flood plain, the C value also shows a regional difference declining trend.