Analysis on the Change Characteristics of Haze in Dezhou City in Recent 40 Years

[Objective] The aim was to analyze the change characteristics of haze in Dezhou City. [Method] Based on the data of haze and sunshine duration from 11 counties or cities in Dezhou City from 1970 to 2009, the daily, monthly, seasonal and annual variation of haze and their variation reasons were studied, meanwhile, the effects of haze on sunshine duration were discussed. [Result] Haze occurred most frequently from 09:00 to 14:00 and daily variation was different in various seasons; haze days were the most in December (200 d), and next came January (161 d), while hazes days were the fewest in August (20 d). From seasonal variation, haze appeared most frequently in winter, accounting for 40% of that in total year, autumn (23%) and summer (20%) the second, and haze days were the fewest in spring (18%). For annual variation, haze days were the fewest from 1970 to 1979 (110 d) and most from 2000 to 2009 (724 d), with the tendency rate of 2.27 and 16.35 d/a, respectively. From regional distribution, haze days were the most in Decheng District, and next came Xiajin, while Yucheng had the fewest haze days. In addition, the annual variation of haze days was related to pollutant concentration in atmosphere, while monthly variation and seasonal variation were controlled by weather situation and meteorological condition. [Conclusion] The study could provide scientific reference for the prevention and impact assessment of haze.

Climatic Change Characteristics of Sunshine Hours and Cause Analysis in Lianyungang City

[Objective]The research aimed to study climatic change characteristics of sunshine hours in Lianyungang and analyze its formation reason. [Method]Based on monthly sunshine hours,precipitation,cloudiness,haze days and vapor pressure from 7 stations of Lianyungang from 1961 to 2010,monthly,seasonal,annual and interdecadal change trends of the sunshine hours were analyzed by using MK test,linear trend analysis and Morlet wavelet. Meanwhile,the cause of change characteristics was analyzed. [Result] Monthly sunshine hours of Lianyungang showed bimodal distribution,and seasonal and annual sunshine hours had decreasing trend at different degrees. The interdecadal change of sunshine hours showed wave characteristics. The annual sunshine hours had multiple temporal-spatial scale features,and there was an obvious mutation in the late 1980s. Sunshine hours in Lianyungang was closely related to visibility,cloudiness,vapor pressure and haze,and they were important factors causing that sunshine hours significantly declined. [Conclusion]The research could provide reference basis for scientifically developing and using solar energy resource and reasonably adjusting industrial and agricultural structures.

Analysis on Change Characteristics and Forecast Factors of the Fog in Beibei District of Chongqing

[Objective] The research aimed to analyze change characteristics and forecast factors of the fog in Beibei District of Chongqing from 1953 to 2010. [Method] By observation data of the fog in Beibei District from 1953 to 2010, interdeoadal, interannual, seasonal and monthly varia- tion characteristics of the fog days and formation-dispersion time of the fog were conducted statistical analysis. Meteorological conditions and fore- cast factors of the fog were also analyzed. [Result] Distribution of the fog days in Beibei District had obvious interdecadal characteristics. Fog days was at its maximum in the 1980s while minimum in the 1960s. Fog duration presented slow increase trend. Interannual characteristic of the fog days overall presented increase trend, and it had 9-year periodic oscillation characteristic. Fog mainly concentrated in autumn and winter. Fog was mainly formed at night （20：00 -08：00） and dispersed in the daytime （08：00 -13：00）. Meteorological conditions which affected heavy fog in Beibei District were water vapor and stratification, wind field, temperature, relative humidity and so on. [ Conclusion] The research provided theoretical basis for scientific predication and forecast of the fog in Beibei District.

The change characteristics of the calculated wind wave fields near lateral boundaries with SWAN model

Since the wind wave model Simulating Waves Nearshore （SWAN） cannot effectively simulate the wave fields near the lateral boundaries, the change characteristics and the distortion ranges of calculated wave factors including wave heights, periods, directions, and lengths near the lateral boundaries of calculation domain are carefully studied in the case of different water depths and wind speeds respectively. The calculation results show that the effects of the variety of water depth and wind speed on the modeled different wave factors near the lateral boundaries are different. In the case of a certain wind speed, the greater the water depth is, the greater the distortion range is. In the case of a certain water depth, the distortion ranges defined by the relative errors of wave heights, periods, and lengths are different from those defined by the absolute errors of the corresponding wave factors. Moreover, the distortion ranges defined by the relative errors decrease with the increase of wind speed; whereas the distortion ranges defined by the absolute errors change a little with the variety of wind speed. The distortion range of wave direction decreases with the increase of wind speed. The calculated wave factors near the lateral boundaries with the SWAN model in the actual physical areas, such as Lake Taihu and Lake Dianshan considered in this study, are indeed distorted if the calculation domains are not enlarged on the basis of actual physical areas. Therefore, when SWAN is employed to calculate the wind wave fields near the shorelines of sea or inland lakes, the appropriate approaches must be adopted to reduce the calculation errors.

Study on Temporal-spatial Change Characteristics of the Extremely Low Temperature Climate Event in Winter of China

[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961 -2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in win- ter of China in 48 years were analyzed. [ Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the eady 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21= century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan - Kweichow Plateau and Hexi Corridor. [ Conclusion] The research provided reference for eady warning of the extremely low temoerature event in China.

Analysis on Change Characteristics of the Average Temperature in Sichuan in 50 Years

[Objective] The research aimed to analyze change characteristics of the average temperature in Sichuan in 50 years.[Method] By using average temperature data at 156 stations of Sichuan from 1961 to 2010,interannual and interdecadal evolution characteristics,regional and seasonal differences of the average temperature in Sichuan in 50 years were analyzed.[Result] Variations of the average temperatures in the whole province and each climatic region in 50 years all presented rise trends.Rise amplitude of the average temperature was obvious in the prior 10 years of the 21st century.Rise amplitude of the temperature was 0-0.5 ℃ in 48.7% of stations in the whole province,and was 0.5-1.0 ℃ in 32.3% of stations.Rise amplitude of the temperature was the maximum in winter.The second one was in spring,and the minimum was in autumn.The annual average temperature in the whole province in 50 years presented east-high-west-low spatial distribution.The regional difference was from-1.2 to 20.9 ℃,and temperature difference was 22.1 ℃.Interannual variation of the average temperature from 1961 to 1997 in the whole province was relatively stable.After that,it presented obvious fluctuation rise trend.Interdecadal variation of the average temperature from the 1960s to the 1990s was relatively stable,and average temperatures were from 8.56 to 8.86 ℃.The maximum interdecadal average temperatures in the whole province and each climatic region all emerged in the prior 10 years of the 21st century,while emergence decades of the minimums were different.[Conclusion] The research provided reference for analyzing climatic change characteristics in Sichuan.

Analysis on Change Characteristics of Sunshine in Benxi Mountainous Area in Recent 57 Years

[Objective] This study aimed to analyze the change characteristics of sunshine hours in Benxi mountainous area in recent 57 years.[Method] Based on the data of monthly sunshine hours,total cloudiness,vapor pressure and ≥0.1 mm precipitation days from Caohekou weather station during 1954-2010,by using linear tendency,Mann-Kendall method and wavelet analysis,the change characteristics of sunshine hours in Benxi mountainous area in recent 57 years were analyzed,as well as the possible climatic factors resulting in the decrease of sunshine hours.[Result] In recent 57 years,except for the slight increase of sunshine hours in winter,annual sunshine hours and sunshine hours in other seasons showed significantly decreasing trend,and annual sunshine hours varied abruptly in 1971.In addition,total cloudiness,vapor pressure and ≥0.1 mm precipitation days affected sunshine hours obviously,but sunshine hours didn’t simply increase as the reduction of total cloudiness and ≥0.1 mm precipitation days,which showed that the influencing factors of sunshine hours were complex.[Conclusion] The research could provide scientific references for the reasonable utilization of light energy,adjustment of agricultural industrial structure and sustainable development of agricultural economy in mountainous areas.

Direct Digital Frequency Control Based on the Phase Step Change Characteristic between Signals

We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude.

Analysis on Change Characteristics of Diurnal Temperature Range in Benxi County from 1958 to 2010

Based on annual mean maximum and minimum temperatures,diurnal temperature range,precipitation,sunshine,total cloud cover and water barometric pressure data in Benxi County from 1958 to 2010,using statistical analysis,the results show that the annual and seasonal diurnal temperature ranges present significant decreasing tendencies,and the reducing tendency is the most remarkable in winter. Autumn reducing tendency is stronger than that in spring,and it is the weakest in summer. Annual and seasonal average temperatures,average maximum and minimum temperatures all present the remarkable rising trends. Rising trend of the minimum temperature is more significant than that of the maximum temperature. The monthly mean diurnal temperature range also presents reducing tendency,and the most reducing scope appear in January and February. Annual and season diurnal temperature range changes are related to sunshine,mean minimum temperature,mean maximum temperature,precipitation,total cloud cover and water barometric pressure,but various essential factors are different in each season. Annual mean temperature,annual mean minimum temperature,annual mean maximum temperature and annual diurnal temperature range all have sudden changes,but the age is inconsistent.

Characteristics of Changes in Karst Rocky Desertification in Southtern and Western China and Driving Mechanisms

The karst landform is a typical ecologically vulnerable region,and the problem of karst rocky desertification in southtern and western China has led to impoverishment and a degraded local ecological environment,which severely limits local socioeconomic development.An effective and appropriate control of karst rocky desertification in southtern and western China requires knowledge about its characteristics of variation and driving mechanisms.In this study,we chose eight regions in the southtern and western China as research areas and analysed the characteristics of the changes in karst ecosystem patterns and rocky desertification from 2000 to 2015.Based on these characteristics,we present the mechanisms that drive karst rocky desertification in the southtern and western China by utilizing the redundancy analysis(RDA)ordination method.The results show that the total area of rocky desertification in southtern and western China had been continuously decreasing from 2000 to 2015,revealing a positive development trend in rocky desertification.Rocky desertification variations were mainly affected by human activities.The reduction in farmland area improved farmland management and increased regional gross industrial product,which together with continuously rising gross domestic product of the tertiary industry caused a positive rocky desertification development.However,the local karst tourism has a certain effect on inducing slight rocky desertification.

Numerical Study for Characteristic Change of Asian Summer Monsoon Circulation and Its Influence Mechanism during the EI Nino Period

In this paper, the relation between Asian summer monsoon circulation and sea surface temperature anomalies over equatorial central-eastern Pacific is investigated by using a global spectral model. This model has nine layers in the vertical and the model variables are represented in the horizontal as truncated expansions of the surface spherical harmonics with rhomboidal truncation at wave number 15. The model involves comparatively complete physical processes and parameterizations with mountains.Using the above model, two experimental schemes are designed, namely control case and anomalous sea surface temperature case. The above two schemes are respectively integrated for forty days and the simulated results are obtained from the last 30-day averaged simulations.The simulations show that positive SST anomalies over equatorial central-eastern Pacific weakens Indian monsoon circulation,decreases precipitation in Indian sub-continent whereas it intensifies East Asian monsoon circulation and increases precipitation in East Asian area. All these results reflect the characteristics of Asian summer monsoon during the El Nino period. In this paper, SST anomalies over equatorial central-eastern Pacific have a direct influence on the intensity and position of subtropical high via the wave train over Northern Hemisphere, which is similar to that suggested by Nitta(1987) and the wave train over Southern Hemisphere has an influence on the intensity of Muscarene high and Australia high resulting in affecting cross equatorial flow. As a result, atmospheric interior heat sources and sinks are redistributed because of the change of cross equatorial flow. And the response of atmosphere to the new heat source and sink has a significant influence on Asian summer monsoon.

Characteristics of change of humic substance in soil in degraded grass lands

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Anisotropic dynamic permeability model for porous media

Based on the tortuous capillary network model,the relationship between anisotropic permeability and rock normal strain,namely the anisotropic dynamic permeability model(ADPM),was derived and established.The model was verified using pore-scale flow simulation.The uniaxial strain process was calculated and the main factors affecting permeability changes in different directions in the deformation process were analyzed.In the process of uniaxial strain during the exploitation of layered oil and gas reservoirs,the effect of effective surface porosity on the permeability in all directions is consistent.With the decrease of effective surface porosity,the sensitivity of permeability to strain increases.The sensitivity of the permeability perpendicular to the direction of compression to the strain decreases with the increase of the tortuosity,while the sensitivity of the permeability in the direction of compression to the strain increases with the increase of the tortuosity.For layered reservoirs with the same initial tortuosity in all directions,the tortuosity plays a decisive role in the relative relationship between the variations of permeability in all directions during pressure drop.When the tortuosity is less than 1.6,the decrease rate of horizontal permeability is higher than that of vertical permeability,while the opposite is true when the tortuosity is greater than 1.6.This phenomenon cannot be represented by traditional dynamic permeability model.After the verification by experimental data of pore-scale simulation,the new model has high fitting accuracy and can effectively characterize the effects of deformation in different directions on the permeability in all directions.

Analysis of Climate Characteristics of Sunshine Hours in Dalian City in Recent 59 Years

[Objective] The aim was to analyze the changes characteristics of sunshine hours of Dalian City. [Method] Based on the data of sunshine hours of Dalian City during 1951 to 2009 and by dint of linear estimation and accumulation anomaly, the change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were analyzed. [Result] The change characteristics of decade, annual, seasonal, monthly sunshine hours in Dalian City were in a decrease trend since recent 59 years. The average sunshine hour in 1950s was the maximum one. Since 21st century, the annual sunshine hour was the lowest one. Annual average sunshine hours were the highest in 1978, and lowest in 2003. There were more sunshine hours before 1989 and later less. Among the four seasons, the sunshine hours in autumn decreased fastest and slowest in spring. The monthly average sunshine hours were the most in May and least in December; the sunshine hours in each month decreased fastest in July. It showed increasing tendency only in March. [Conclusion] The study supplied scientific reference for the reasonable utilization of light energy, agricultural production structure and sustainable development of agricultural economy.

Analysis on Variation Characteristics of the Precipitation in Zigong City in Recent 50 Years

[Objective] The research aimed to analyze variation characteristics of the precipitation in Zigong City in recent 50 years.[Method] Based on daily precipitation data at three observation stations in Zigong City from 1961 to 2010,linear tendency method and accumulative anomaly method were adopted to analyze climatic change characteristics of the annual,seasonal,monthly rainfalls and rain days in Zigong City in recent 50 years.[Result]The annual rainfall overall presented a decreasing trend at the variation tendency rate of-28.0 mm /10 a in Zigong City.The annual rain days obviously declined at the variation tendency rate of-5.6 d /10 a.The decline of rain days was more obvious than that of the rainfall.Decline of the light rain days was especially serious.Not only trends of summer,autumn and winter rainfalls were all negative,but also trends of the four-season rain days were all negative.Reductions of autumn rainfall and rain days were the most remarkable and the largest in magnitude.Monthly rainfall presented single-peak type distribution,and monthly rain days presented double-peak type distribution.Days of each-level precipitation within one year in each area of Zigong City were nearly consistent.Moreover,rain days decreased as magnitude increased.An obvious characteristic of the precipitation variation in Zigong City in recent 50 years was synchronal decrease of the annual rainfall and rain days.[Conclusion]In general,the natural rainfall resource in Zigong City was tending to reduce,and autumn drought was obvious.

Analysis of Changing Characteristics of Evaporation in Cangzhou City in Recent 40 Years

[Objective] The study aimed to analyze the changing characteristics of evaporation in Cangzhou City in recent 40 years.[Method] Based the observation data of evaporation measured by small evaporation pans （with the caliber of 20 cm） from weather stations of Cangzhou dur- ing 1971 -2010, the monthly, seasonal, annual and decadal variation of evaporation were analyzed using conventional assessment methods. [Result] During 1971 -2010, monthly average evaporation in Cangzhou fluctuated within a year, and the maximum value appeared in June, while the minimum value appeared in January. Within a year, average evaporation was the highest in summer, and its variation was the greatest; it was the lowest and varied most slightly in winter. During 1971 -2010, evaporation in winter showed an increasing trend, while evaporation showed a de- creasing trend in spring and autumn, and there was no obvious change in evaporation in summer. Annual average evaporation in Cangzhou showed a decreasing trend from 1971 to 2010, and the highest evaporation reached 2 273.3 ram, appearing in 1972. The lowest evaporation was only 1 681.4 mm, appearing in 1990, and the difference between them reached 591.9 mm. Average evaporation in each decade showed a decrease trend, and the maximum value appeared in the 1980s （1 958.6 mm）, while the minimum value appeared in the first ten years of the 21st century （1 880.9 mm）. [ Conclusion] The research could provide theoretical references for studies on climate change in Cangzhou in future.

Research on the Variation of Population Distribution and Its Characteristics Based on Spatial Autocorrelation Method: A Case Study of Poyang Lake Region in Jiangxi Province

According to Statistical Yearbook of Jiangxi Province(2001～2006),We analyze the time-space variation of population distribution of Poyang Lake region from the two points of view.The former is quality of population,which involves culture structure,occupational structure,age structure and sex structure of population.The latter is quantity of population,which only involves the amount of population.Furthermore,we can reveal the internal relations and action mechanism of variation of population distribution by analyzing the regional economic development,population urbanization,land use and ecological landscape of Poyang Lake region.It is important to provide help for region planning,ecological landscape planning and environmental protection by correct understanding the man-land relationship of natural-human ecosystem in Poyang Lake region.

Variation Characteristics of Thermal Resources in East Hexi Corridor in Recent 50 Years

[Objective] The aim was to study variation characteristics of thermal resources in east Hexi Corridor in recent 50 years. [Method] Using the daily average air temperature data from 5 meteorological stations in east Hexi Corridor from 1959 to 2010, the variation of accumulated temperature steadily above 10 and 0 ℃, lasting days, the beginning and ending day were summarized, and then the variation characteristics of thermal resources under the background of climate warming were analyzed. [Result] The air temperature increased continuously in east Hexi Corridor, and the climatic trend rate of the annual average air temperature was 0.34 ℃/10 a, more significant than any other region in China. And it was well correlated with the thermal resource indexes such as the accumulated temperature steadily above 10 and 0 ℃, and their lasting days, and the beginning and ending day. Climate warming had made the accumulated temperature steadily above 10 and 0 ℃ increased significantly in east Hexi Corridor widespread. The accumulated temperature steadily above 10 and 0 ℃ had increased significantly. The lasting days of accumulated temperature steadily above 10 and 0 ℃ increased significantly too. The delay of ending days was more significant than the advancing of beginning days. [Conclusion] These changes in thermal resources were conductive to increase food production and maintain the stability of food production in east Hexi Corridor.

Changing Characteristics of Temperature in Longnan City in Recent 54 Years

Based on the observation data of temperature in Chengxian meteorological station（ the climate representative station of Longnan City,Gansu Province） during 1961-2014,the annual,seasonal and monthly changes of temperature were analyzed,and the abrupt changes in relevant variables were tested using the cumulative anomaly method. The results showed that annual average temperature in Chengxian County increased by 0. 138 ℃/10 a in the past 54 years. There was an obvious sudden change in annual average temperature around 1996. The annual average temperature showed a downward trend before 1996 and an upward trend after 1996. Average temperature in spring,summer,autumn and winter increased by 0. 113,0. 028,0. 157 and 0. 259 ℃/10 a respectively. The fluctuation of average temperature in spring and winter was the largest,followed by summer,while the fluctuation was the smallest in autumn. There were certain differences between various seasons in terms of the years with sudden changes in average temperature,which was not consistent with the years with the sudden changes in annual average temperature. The changing rate of monthly average temperature was the largest in February（ up to 0. 412 ℃/10 a）,followed by March,April and November,but it was the smallest in May（ only 0. 005 ℃/10 a）. The maximum of monthly average temperature appeared mostly in the 21 stcentury,while the minimum appeared in the 20 thcentury.