Trend Of Temperature Variation Research Articles

ĐÁNH GIÁ SỰ PHÂN HOÁ VỀ XU THẾ BIẾN ĐỔI CỦA NHIỆT ĐỘ TRONG BỐI CẢNH BIẾN ĐỔI KHÍ HẬU TẠI TỈNH BẮC GIANG

Bac Giang is a province in the northern midland and mountainous region of Vietnam. Bac Giang has many potentials and advantages in terms of natural conditions and human resources for economic development. However, climate change has been having a great impact on the socio-economic development of the province. The study applied the correlation assessment method and regression analysis to process temperature data at 4 meteorological stations: Bac Giang, Hiep Hoa, Son Dong, and Luc Ngan. The results demonstrate that in 44 years (1970 - 2014) the trend of change in average temperature is from 0.012 oC\year to 0.018 oC\year. On the other hand, the changing trend of the annual absolute maximum temperature is common at a higher level, from 0.028 oC\year to 0.032 oC\year. The variability of extreme temperature values is much broader than that of the average temperature. The trend of temperature variation (average temperature, annual absolute maximum temperature) is highest in the eastern territory of the province, in mountainous districts including Son Dong, Luc Ngan, and lowest in the western lowland areas namely Hiep Hoa district. The research results will be the assisting tool for management agencies to find solutions to develop socio-economic adaptation to climate change.

Potential of AOD Retrieval Using Atmospheric Emitted Radiance Interferometer (AERI)

Aerosols in the atmosphere play an essential role in the radiative transfer process due to their scattering, absorption, and emission. Moreover, they interrupt the retrieval of atmospheric properties from ground-based and satellite remote sensing. Thus, accurate aerosol information needs to be obtained. Herein, we developed an optimal-estimation-based aerosol optical depth (AOD) retrieval algorithm using the hyperspectral infrared downwelling emitted radiance of the Atmospheric Emitted Radiance Interferometer (AERI). The proposed algorithm is based on the phenomena that the thermal infrared radiance measured by a ground-based remote sensor is sensitive to the thermodynamic profile and degree of the turbid aerosol in the atmosphere. To assess the performance of algorithm, AERI observations, measured throughout the day on 21 October 2010 at Anmyeon, South Korea, were used. The derived thermodynamic profiles and AODs were compared with those of the European center for a reanalysis of medium-range weather forecasts version 5 and global atmosphere watch precision-filter radiometer (GAW-PFR), respectively. The radiances simulated with aerosol information were more suitable for the AERI-observed radiance than those without aerosol (i.e., clear sky). The temporal variation trend of the retrieved AOD matched that of GAW-PFR well, although small discrepancies were present at high aerosol concentrations. This provides a potential possibility for the retrieval of nighttime AOD.

Spatial and Temporal Variation of the Near-Surface Wind Environment in the Sahara Desert, North Africa

The Sahara Desert is the largest source of dust on Earth, and has a significant impact on global atmospheric changes. Wind is the main dynamic factor controlling the transport and intensity of dust in the Sahara Desert. This study comprehensively analyzed the spatial and temporal variation in the wind regime of the Sahara Desert from 1980 to 2019 using data from 17 meteorological stations to improve awareness of global atmospheric changes and the intensity of regional aeolian activities. All wind speed parameters decreased from northwest to southeast. While there were significant differences in the trends of temporal variation in wind speed among the different regions, there was an overall decreasing trend across the Sahara Desert, with an average wind speed of 0.09 m s−1 10 a−1. This decrease was closely related to wind frequency. The easterly, westerly, and northerly winds dominated, with more complex wind direction in the northern region. Seasonal differences in wind direction were observed in all regions. The wind direction frequency of wind speeds >6 m s−1 exceeded those with wind speeds <6 m s−1 in the western and northern regions, whereas other regions showed an opposite pattern. The highest drift potential (DP) and resultant drift potential (RDP) were found in the western and northern regions, and during spring and winter. There was a trend of decreasing annual variation in DP and RDP in all regions. The directional variability (RDP/DP) indicated mostly intermediate and high variability in wind direction. Resultant drift direction (RDD) indicated that a mainly southwest wind direction. No apparent trends in temporal variation in RDD and RDP/DP were observed. Total DP was strongly influenced by DP and the magnitude and frequency of strong winds in the prevailing wind direction. No strong correlation between wind regimes and dune types was observed in this desert, indicating the complexity of factors affecting dune morphology.

Analysis of the Single Coal Particle Combustion Process under O2/CO2 Atmosphere Based on Spectral Diagnostics Technology: Combination of Spectroscopic Characteristics and Flame Temperature

This work studies the single coal particle combustion process in an O2/CO2 atmosphere based on spectral diagnostics technology in a visual drop tube furnace (VDTF). The chemiluminescence characteristics of OH*, CH*, Na*, and K* in single coal particles at two reaction stages and different oxygen fractions (Xi,O2) are investigated. The results show that both flame temperature and alkali metal spectral intensity increase first and then decrease, and the trend of temperature variation is consistent with that of alkali metal spectral intensity. Meanwhile, with Xi,O2 increases, Na* and K* peak intensities are enhanced because of the improvement in the oxygen flow rate. In the volatile reaction stage, the coal particle shows a typical envelope flame with high soot generation and luminosity. As the reaction time increases from 10 to 30 ms, the flame size increases and the flame temperature increases from 1550 to 1950 K. The spectroscopic results corresponding to the volatile reaction stage show that, as Xi,O2 increases from 30 to 50, the OH* and CH* intensity peaks increase linearly. Moreover, the intensities of the Na* and K* peaks increase by approximately 50.2 and 89.2%, respectively. During the volatile–char reaction stage, the coal particle exhibits a brighter luminous characteristic. As the reaction time increases from 40 to 70 ms, the flame size reduces and the flame temperature decreases from 1900 to 1700 K. The spectroscopic results corresponding to the volatile–char reaction stage indicate that, with the increase in Xi,O2, the positions of the OH* and CH* peaks change little and the intensities of the Na* and K* peaks increase by 21.3 and 75.1%, respectively. Our results prove that the flame temperature and alkali metal atomic emission spectroscopy exhibit the same trends as a function of the reaction time, and the alkali metal atomic emission spectroscopy can be used to characterize the flame temperature.

Colorectal cancer burden, trends and risk factors in China: A review and comparison with the United States.

China and the United States (the U.S.) have the heaviest colorectal cancer (CRC) burden with considerable variations in temporal trends. This study aims to analyze the temporal patterns of CRC burden and its risk factors in China and the U.S. across the past three decades. Data were extracted from the Global Burden of Disease (GBD) Study in 2019, including cases, deaths, disability-adjusted life-years (DALYs), age-standardized rate (ASR), and summary exposure value (SEV) of CRC in China and the U.S. between 1990 and 2019. Annual average percentage changes (AAPCs) of CRC burden were calculated using the Joinpoint regression model. The mortality in CRC attributable to potential risk factors was characterized by countries, gender, and age groups. In 2019, there were 607,900 and 227,241 CRC cases, and 261,777 and 84,026 CRC deaths in China and the U.S., respectively. The age-standardized incidence rate (ASIR) was 30.55 per 100,000 in China and 41.86 per 100,000 in the U.S., and the age-standardized mortality rate (ASMR) was 13.86 per 100,000 in China and 14.77 per 100,000 in the U.S. CRC incidence, mortality, and DALY rate in the U.S. showed downward trends in the past three decades (AAPC=-0.47, -1.06, and -0.88, respectively), while upward trends were observed in China (AAPC=3.11, 1.05, and 0.91, respectively). Among the cause of CRC, the leading risk factor contributing to CRC death was low milk in China and smoking in the U.S., respectively. From 1990 to 2019, the burden of CRC in China increased dramatically, particularly for males and middle-aged and elderly people. The management of the major risk factors associated with the high burden of CRC should be enhanced.

青藏高原两种高寒草地植被变化及其水温驱动因素分析

高寒草甸和高寒草原作为青藏高原两种重要植被类型，研究其植被变化与气候变化相关性，有助于为青藏高原两种高寒草地生态系统应对全球气候变化管理提供参考。以位于同纬度的三江源高寒草甸和阿里高寒草原为研究对象，基于植被净初级生产力（Net Primary Productivity，NPP）变化表征植被变化，利用NPP数据和气象数据，分别分析两地2000-2017年植被NPP、降水和气温时空变化差异；利用Sen+Mann-Kendall趋势检验，研究两种高寒草地气候与植被净初级生产力变化趋势；以县域统计年鉴牛羊肉产量表征放牧强度，研究放牧活动对高寒草地植被变化的影响；通过Pearson相关和偏相关分析方法，分别研究降水和气温对两种高寒草地植被NPP变化影响差异。研究结果表明：（1）2000-2017年三江源高寒草甸和阿里高寒草原区年平均气温以0.085℃/a和0.084℃/a的趋势上升，降水以平均每年3.87 mm和2.23 mm的趋势增加，高寒草甸区变暖变湿速率较高寒草原区快。（2）三江源高寒草甸和阿里高寒草原植被NPP均呈现由东南向西北逐渐降低空间格局；2000-2017年高寒草甸区57.7%植被NPP呈现上升趋势，而高寒草原区50.96%植被NPP呈现上升趋势，高寒草甸植被NPP增长趋势较高寒草原明显。（3）三江源高寒草甸和阿里高寒草原两种草地植被变化受放牧影响不大，受气候变化影响较大。（4）三江源高寒草甸大部分植被NPP增长与气温呈显著正相关而与降水呈显著负相关，高寒草甸植被NPP主要受温度调控，而阿里高寒草原植被NPP受降水和温度的双重调控。;Alpine meadow and alpine steppe are two important vegetation types on the Qinghai-Tibet Plateau. Studying the correlation between vegetation change and climate change in alpine meadow and alpine steppe is helpful to provide reference for the management of the two alpine grassland ecosystems on the Qinghai-Tibet Plateau in response to global climate change. In this study, the alpine meadow of the Three-River Headwaters Region and the alpine steppe of Ali located in the same latitude were taken as the research objects. Vegetation changes were characterized based on the changes of Net Primary Productivity (NPP) of vegetation. Based on NPP data and meteorological data, the spatial and temporal variations of NPP, precipitation and air temperature between 2000 and 2017 were analyzed. Sen+ Mann-Kendall trend test was used to study the change trend of climate and vegetation net primary productivity in two alpine grasslands. The effects of grazing activities on the vegetation change of alpine grassland were studied by using the yield of beef and mutton in county statistical yearbooks. Through Pearson correlation and partial correlation analysis, the variation trend of precipitation and air temperature on vegetation NPP and the difference of precipitation and air temperature on NPP of two alpine grasslands were studied respectively. The results show that:(1) from 2000 to 2017, the annual average temperature in Three-River Headwaters Region alpine meadow and Ali alpine steppe increased at 0.085℃/a and 0.084℃/a, and the annual average precipitation increased at 3.87 mm and 2.23 mm, respectively. The warming and wetness rate in the alpine meadow was faster than that in the alpine steppe. (2) The NPP of the alpine meadow in the Three-River Headwaters Region and the alpine steppe in Ali showed a decreasing spatial pattern from southeast to northwest. From 2000 to 2017, the NPP of 57.7% of alpine meadow vegetation presented an upward trend, while that of 50.96% of alpine steppe vegetation showed an upward trend. The NPP of alpine meadow vegetation increased more obviously than that of alpine steppe. (3) The alpine meadow in the Three-River Headwaters Region and the alpine steppe in Ali region were less affected by grazing and more affected by climate change. (4) The NPP growth of most alpine meadow vegetation in the Three-River Headwaters Region was significantly positively correlated with air temperature and negatively correlated with precipitation. The NPP of alpine meadow vegetation was mainly regulated by temperature, while the NPP of alpine steppe vegetation in the Ali region was controlled by both precipitation and temperature.

Population-based dynamical modelling for global warming mitigation assessment by nuclear energy resource

Climate change is analysed by the global population growth incorporated with the energy and its related social aspect consequences where the energy-mix policy has been issued to mitigate the carbon production fossil fuels such as oil and coal. In the simulation study, there are comparisons using three types of the population growth rate. Results show the temperature change where the variations of average temperature for 2020 are analysed in three cases of regions. The highest value is on 4th year as 4.49 in type 1 (land). So, the indirect method of the population growth to reduce the world temperature could be analysed as another way to treat the climate change. The other regional effect could be studied in the future work to find out the trend of nation and temperature variations.

Spatio-temporal variation of reference crop evapotranspiration and its climatic mechanism in Nenjiang River Basin, China

To understand the temporal and spatial variations of reference crop evapotranspiration (ET0) in Nenjiang River Basin, and clarify the effects of climatic factors on ET0, we calculated the daily ET0 of each station in Nenjiang River Basin from 1970 to 2019 by Penman-Monteith formula, analyzed the temporal variation trend and spatial distribution pattern of ET0. We further quantitatively examined the sensitivity of ET0 to meteorological factors by sensitivity analysis, and explored the contribution of meteorological factors to ET0 changes. The results showed that ET0 generally showed an insignificant decreasing trend during the study period in the Nenjiang River Basin. ET0 decreased in spring, summer, and autumn, but increased in winter, and decreased from southeast to northwest. ET0 had the highest sensitivity to relative humidity at both temporal and spatial scales. The sensitivity coefficients of mean temperature, relative humidity and wind speed increased gradually, while that of sunshine hours decreased gradually. ET0 was sensitive to mean temperature in northern Greater Khingan Mountains and Lesser Khingan Mountains, while to wind speed in southern Greater Khingan Mountains and Songnen Plain. Wind speed was the main factor affecting the change of ET0 in the whole year, spring, autumn, and winter. Sunshine hours was the main affecting factor in summer. The mean temperature and relative humidity had the greatest contribution to ET0 in the north of Greater Khingan Mountains and Lesser Khingan Mountains, and it was the wind speed in Songnen Plain.

Effect of urbanization on extreme temperature events in Liaoning Province, China, from a spatiotemporal perspective

Understanding the role of urbanization in extreme temperature events can help mitigate their negative impacts. This study aimed to comprehensively analyze the effect of urbanization on extreme temperature events in Liaoning Province, China, from a spatiotemporal perspective. First, eight extreme temperature indices were selected from the temperature data for the period 1959–2018. Climatic regions corresponding to 24 meteorological stations were divided, and land use data were used to classify urban and rural areas. Then, the dynamic “urban minus rural” method was improved and used to quantify the urbanization effect (UE) and temporal variation trend of extreme temperature events. Furthermore, landscape indices were used to quantify the impact of the spatial layout of urban landscapes on extreme temperatures. The results showed that the UE in the northern region of Liaoning Province was reflected by most indices (minimum urbanization contribution, UC = 9.61%), while that in the southern region was mainly observed at night (maximum UC = 75.00% observed during frost days). The area and fragmentation of the urban landscape were the main spatial factors affecting extreme temperatures, primarily extremely high temperatures at night. Further, the highest correlation coefficient (-0.74) was between the contagion index and tropical nights index.

Spatial and temporal distribution and utilization of water resources in Guangxi and suggestions for their protection

The spatial distribution characteristics of surface water and underground water resources in Guangxi were discussed. The temporal variation trend of surface water and groundwater resources and the present situation of water resources exploitation and utilization in Guangxi in recent 10 years are analyzed. This paper points out the problems of water pollution in the exploitation and utilization of water resources, and puts forward some suggestions on water resources protection and water pollution control in Guangxi.

Characterization of temporal PM2.5, nitrate, and sulfate using deep learning techniques

Water-soluble inorganic salts (WIS) contribute a large fraction of PM2.5, which are responsible for the adverse effects on human health and environment. It is important to investigate the long-term variation trend of PM2.5 and WIS for exposure assessment and effective abatement strategies development. In this study, a multi-step ahead artificial neural network (MSA-ANN) and a long short-term memory fully connected (LSTM-FC) model for PM2.5, nitrate (NO3−), and sulfate (SO42−) prediction were developed to provide high temporal resolution datasets. Results show that the kinetic formation rate of HNO3 and HSO3− used as input variables can improve the accuracy of the present model for PM2.5, NO3−, and SO42− prediction. The MSA-ANN is able to predict 80–83%, 93%, and 91% of PM2.5, NO3−, and SO42−, respectively, with t+1 prediction horizon. With increasing prediction horizon to t+4 and t+8, the present model still can track the temporal variation of PM2.5, NO3−, and SO42− very well and capture the peak values during a severe pollution event. The proposed method is applicable to predict regional temporal variation trend of PM2.5, NO3−, and SO42− and fill the data gap in area with limited WIS measurement.

Effect of MgO on solidification and crystallization properties of ultrahigh-basicity mold flux

The effect of MgO on the solidification and crystallization properties of ultrahigh-basicity mold flux was analyzed (i.e., comprehensive basicity R = 1.75). Results showed that with the increase of MgO content (0–6 wt%), the viscosity, melting temperature and break temperature decreases firstly, and then increases. The change of slag viscosity caused by the change of composition is indistinct, but the variation trend of melting temperature and break temperature is obvious. With the increase of MgO content, the crystallization temperature of ultrahigh-basicity slag decreases gradually, while the crystallization rate decreases firstly, and then increases. When the MgO content reaches 3%, the crystallization rate is the minimum. Research found that Ca4Si2F2O7 is the main precipitated phase in the slag, and as the MgO content continues to increase, the new phases of CaF2 and Ca3MgSi2O8 appear gradually.

A novel comprehensive agricultural drought index reflecting time lag of soil moisture to meteorology: A case study in the Yangtze River basin, China

Soil moisture related agriculture drought usually lags behind meteorological factors. In order to address such a hysteresis, the time lag of soil moisture to meteorological factors were initially investigated based on remote sensing products and meteorological observed data in Yangtze River basin. Soil moisture exhibited different lag times to meteorological factors in different climate regions. There is one month lagged in the northwest of the Yangtze River basin, while two months lagged in the middle and east. A novel Comprehensive Agricultural Drought Index (CADI) was then constructed to reflect the feedback of time lag effects in drought assessment, which comprehensively integrated the lagging times of soil moisture to precipitation and evapotranspiration. The CADI was negatively correlated with Standardized Precipitation Index (SPI), Standard Precipitation Evapotranspiration Index (SPEI), Vegetation Health Index (VHI) and Reconnaissance Drought Index (RDI), among which the SPEI-3 was most strongly correlated. Drought grades captured by CADI had significantly positive correlations to SPI, SPEI, VHI and RDI captured with correlation coefficients between 0.5 and 0.7. Moreover, the CADI was able to effectively monitor the annual and seasonal variations and spatial pattern of agricultural drought, particularly better identify summer droughts, from which the crop phenology related agriculture drought monitoring can benefit. The temporal variation trend of CADI also agreed to the crop drought-affected area. Therefore, the proposed CADI is superior to characterize agricultural drought by eliminating temporally asynchronous effects of meteorology and soil moisture on drought monitoring. It provides scientific support for hazard assessment and mitigation of regional drought management.

Explosion temperature mapping of emulsion explosives containing TiH2 powders with the two-color pyrometer technique

In the study, the two-color pyrometer technique was used to measure the transient temperature field of emulsion explosives with different contents of TiH2 powders. The experimental results showed that the introduction of TiH2 powders could significantly increase the explosion temperature and fireball duration of emulsion explosive. When emulsion explosives were ignited, the average explosion temperature of pure emulsion explosive continuously decreased while emulsion explosives added with TiH2 powders increased at first and then decreased. When the content of TiH2 powders was 6 mass%, the explosion average temperature reached its maximum value of 3095 K, increasing by 43.7% as compared with that of pure emulsion explosive. In addition, the results of air blast experiment and explosion heat test showed that the variation trends of shock wave parameters, explosion heat and theoretical explosion temperature of emulsion explosives with different contents of TiH2 powders were basically consistent with that of explosion temperature measured by the two-color pyrometer technique. In conclusion, the two-color pyrometer technique would be conducive to the formula design of emulsion explosive by understanding the explosion temperature characteristics.

High-resolution analysis of observed thermal growing season variability over northern Europe

Strong historical and predicted future warming over high-latitudes prompt significant effects on agricultural and forest ecosystems. Thus, there is an urgent need for spatially-detailed information of current thermal growing season (GS) conditions and their past changes. Here, we deployed a large network of weather stations, high-resolution geospatial environmental data and semi-parametric regression to model the spatial variation in multiple GS variables (i.e. beginning, end, length, degree day sum [GDDS, base temperature + 5 °C]) and their intra-annual variability and temporal trends in respect to geographical location, topography, water and forest cover, and urban land use variables over northern Europe. Our analyses revealed substantial spatial variability in average GS conditions (1990–2019) and consistent temporal trends (1950–2019). We showed that there have been significant changes in thermal GS towards earlier beginnings (on average 15 days over the study period), increased length (23 days) and GDDS (287 °C days). By using a spatial interpolation of weather station data to a regular grid we predicted current GS conditions at high resolution (100 m × 100 m) and with high accuracy (correlation ≥ 0.92 between observed and predicted mean GS values), whereas spatial variation in temporal trends and interannual variability were more demanding to predict. The spatial variation in GS variables was mostly driven by latitudinal and elevational gradients, albeit they were constrained by local scale variables. The proximity of sea and lakes, and high forest cover suppressed temporal trends and inter-annual variability potentially indicating local climate buffering. The produced high-resolution datasets showcased the diversity in thermal GS conditions and impacts of climate change over northern Europe. They are valuable in various forest management and ecosystem applications, and in adaptation to climate change.

Water Quality Evaluation of Wenyu River Based on Single Factor Evaluation and Comprehensive Pollution Index Method

Wenyu River is the “mother river” in Beijing. In recent years, the research on the water quality of the Wenyu River has increased gradually. In this paper, the monitoring data at Shahe Reservoir, Lu Tuan Gate, Xin Bao Gate, and Ma Fang sections for each month in 2019 were adopted. The single-factor evaluation method and the comprehensive pollution index method were selected to analyze the current situation of the water quality of Wenyu River in the Chang Ping section and its temporal and spatial variation trend. The single factor evaluation method showed that the dissolved oxygen exceeded the standard seriously in all other months of the year except that the situation was better in May, June, and July. The ammonia nitrogen content reached the highest level in January, followed by a month-by-month decreasing trend. After June, each section basically met the requirements of Class v water quality. The comprehensive pollution index method shows that the water quality of Shahe reservoir varies greatly throughout the year, and it is in grade v for 6 months. The evaluation results of both methods show that the water quality of all sections of Wenyu River in 2019 was mostly in category v.

Analysis of cavities characteristics of underwater pulsed current discharge

In order to analyze the motion characteristics of pulsed discharge cavities in water, the process of cavities motion were obtained by a combining shadow method and high-speed camera. Through detailed data analysis and calculation, the theoretical motion process of cavities in water is obtained by the Rayleigh–Plesset model. The comparison between the theoretical results and the experimental data shows that the model can reproduce the motion process of cavities well. The variation trend of pressure and temperature in cavities is given, and the characteristics of the cavitiy motion period, radius and initial energy under different voltages are analyzed. Finally, the mass diffusion and heat transfer are calculated quantitatively. The results provide a basis for analyzing the generation process of secondary shock waves and perfecting the theoretical system of pulsed discharge in water.

Impact of climate change on the spatio-temporal characteristics of meteorological and hydrological drought over the Lancang-Mekong River basin

Affected by global climate change, the status of meteorological and hydrological drought in the Lancang-Mekong River basin (LMRB) has witnessed great changes. Therefore, predicting the temporal and spatial variations of future drought as well as its propagation characteristics has become the basis for tackling climate changes and conducting cooperation on the water resources of the Mekong River. By applying the SWAT model and the method of atmosphere-land coupling, both the history (1960-2005) and the future (2022-2050 and 2051-2080) hydrological processes of the LMRB were simulated. Moreover, the future temporal and spatial variation trends of meteorological and hydrological drought were also predicted and analyzed by using the Standardized Precipitation Index and Standardized Runoff Index. The research results indicated that: ① In the future, the amount of precipitation will be increased. Thus, the meteorological drought will be alleviated to some extent, but at the same time, the inhomogeneous distribution of intra-annual precipitation and increased evaporation from the river basin together will cause a severer hydrological drought and an intense propagation process. ② Hydrological drought will have significant spatial heterogeneity. Specifically, the hydrological drought will be the most intense in Jinghong and Chiang Saen stations, followed by Luang Prabang, Mukdahan, and Pakse stations, and be the weakest in Vientiane station. ③ Over time, the frequency of hydrological drought in the river basin will be slightly decreased, but the proportion of heavy drought and severe drought will be increased, and the extreme drought will be enhanced both in amount and strength. Furthermore, the features of spatial variation will be more significant and noticeable.

Recent Changes in Temperature and Precipitation of the Summer and Autumn Seasons over Fujian Province, China

Based on the observation data of daily temperature and precipitation in summer and autumn of 68 representative meteorological stations in Fujian Province from 1971 to 2018, using the climate Tendency Rate, Mann-Kendall trend test, Morlet wavelet analysis and other methods, this paper analyzes the variation trends of air temperature and annual precipitation and the wavelet periodic variation characteristics of annual precipitation time series in summer and autumn of Fujian Province over a period of approximately 48 years. The results show that over the approximately 48 years, the temperature and precipitation in summer and autumn in Fujian showed an obvious upward trend, which had a mutation around 2000, but the mutation time was different, and the precipitation was slightly earlier. The annual temperature and precipitation in summer and autumn experienced three oscillations on the 28a scale. In the 28a time scale of summer autumn seasonal oscillation, there are three negative centers and two positive centers. According to the characteristics of annual average temperature and annual precipitation in the first major cycle, the annual precipitation in summer and autumn will continue to increase in the future.

Analysis of Ozone Pollution Characteristics and Influencing Factors in Northeast Economic Cooperation Region, China

The increase in tropospheric ozone (O3) concentration has become one of the factors restricting urban development. This paper selected the important economic cooperation areas in Northeast China as the research object and collected the hourly monitoring data of pollutants and meteorological data in 11 cities from 1 January 2015 to 31 December 2019. The temporal and spatial variation trend of O3 concentration and the effects of meteorological factors and other pollutants, including CO (carbon monoxide), SO2 (sulfur dioxide), NO2 (nitrogen dioxide), and PM2.5 and PM10 (PM particles with aerodynamic diameters less than 2.5 μm and 10 μm) on ozone concentration were analyzed. At the same time, the variation period of O3 concentration was further analyzed by Morlet wavelet analysis. The results showed that the O3 pollution in the study area had a significant spatial correlation. The spatial distribution showed that the O3 concentration was relatively high in the south and low in the northeast. Seasonally, the O3 concentration was the highest in spring, followed by summer, and the lowest in winter. The diurnal variation of O3 concentration presented a “single peak” pattern. O3 concentration had a significant positive correlation with temperature, sunshine duration, and wind speed and a significant anticorrelation with CO, NO2, SO2, and PM2.5 concentration. Under the time scale of a = 9, 23, O3 had significant periodic fluctuation, which was similar to those of wind speed and temperature.