Spatiotemporal Variation Characteristics of Water Quality in the Yinma River

As an important river in the central part of Jilin Province, the Yinma River plays a crucial role in the daily lives of the people in Jilin Province. In this paper, 15 cross sections were selected in the Yinma River basin. Based on the water quality monitoring data from 2012 to 2021, referring to the Environmental Quality Standards for Surface Water (GB 3838-2002) and historical monitoring data of the river, dissolved oxygen (DO), five-day biochemical oxygen demand (BOD 5), permanganate index (COD Mn ), chemical oxygen demand (COD), ammonia nitrogen (NH 4-N), total phosphorus (TP), and total nitrogen (TN) were determined as 7 evaluation indicators, and the water quality of 15 cross sections in the Yinma River basin was comprehensively evaluated. A characteristic analysis was conducted on the water quality of the Yinma River, and its pollution sources were identified. Based on the conclusions, constructive control measures were proposed.

Variation Characteristics of Water Budget Condition of Heilongjiang Province in Recent 50 Years

Based on the 1961-2010 weather data from 65 meteorological stations in Heilongjiang Province, using the statistic software and GIS, the change characteristics of water budget, including the precipitation, reference evapotranspiration and water budget in the whole year and the temperature-defined growing season, were analyzed. The results indicated that the both the precipitation during the whole year and that of during the temperature-defined growing season from 1961 to 2010 all decreased, while the annual reference evapotranspiration decreased, but the reference evapotranspiration during the temperature-defined growing season presented an increasing trend. The water resources were generally characterized by water deficit, especially in the beginning of 21 st .

Interannual Variability and Scenarios Projection of Sea Ice in Bohai Sea Part Ⅰ: Variation Characteristics and Interannual Hindcast

The Bohai Sea is one of the southernmost areas for sea ice formation in the northern hemisphere.Sea ice disasters in this body of water severely affect marine activities and the safety of coastal residents.In this study,we analyze the variation characteristics of the sea ice in the Bohai Sea and establish an annual regression model based on predictable mode analysis method.The results show the following:1)From 1970 to 2018,the average ice grade is(2.6±0.8),with a maximum of 4.5 and a minimum of 1.0.Liaodong Bay(LDB)has the heaviest ice conditions in the Bohai Sea,followed by Bohai Bay(BHB)and Laizhou Bay(LZB).Interannual variation is obvious in all three bays,but the linear decreasing trend is significant only in BHB.2)Three modes are obtained from empirical orthogonal function analysis,namely,single polarity mode with the same sign of anomaly in all of the three bays and strong interannual variability(82.0%),the north–south dipole mode with BHB and LZB showing an opposite sign of anomalies to that in LDB and strong decadal variations(14.5%),and a linear trend mode(3.5%).Critical factors are analyzed and regression equations are established for all the principal components,and then an annual hindcast model is established by synthesizing the results of the three modes.This model provides an annual spatial prediction of the sea ice in the Bohai Sea for the first time,and meets the demand of operational sea ice forecasting.

INTENSITY INDEX OF SOUTH CHINA SEA MONSOON AND ITS VARIATION CHARACTERISTICS

According to the basic characteristics of the activities of summer monsoon in the South China Sea, a standardized index, sI, has been designed that integrates a dynamic factor (southwesterly component) and a thermodynamic factor (OLR) for the indication of summer monsoon in the South China Sea. With the index determined for individual months of June, July and August and the entire summertime from 1975 to 1999, specific months and years are indicated that are either strong or weak in monsoon intensity. The variation is studied for the patterns and sI抯 relationship is revealed with the onset of summer monsoon and the precipitation in Guangdong province and China. The results show that there are quasi-10 and quasi-3-4 year cycles in the interannual variation of the monsoon over the past 25 years. When it has an early (late) onset, the summer monsoon is usually strong (weak). In the strong (weak) monsoon years, precipitation tends to be more (less) in the first raining season of the year but normal or less (normal) in the second, in the province, but it would be more (less) in northeastern China and most parts of the northern China and south of the lower reaches of the Changjiang River and less (more) in the middle and lower reaches of the river, western part of northern China and western China.

Dynamic Variation Characteristics of Phosphorus in Paddy Field Runoff in Saline Land and Its Potential Environmental Effect

[Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [Method] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed. [Result] Surface water in paddy field was alkaline, and scattered soil had poor fertilizer conservation capacity. Phosphorus accumulated in soil surface, which could increase the risk of phosphorus loss. Phosphorus loss in paddy field mainly occurred in irrigation period and runoff period caused by rainstorm. The concentration of total phosphorus (TP), particulate phosphorus (PP), total dissolved phosphorus (TDP) and dissolved reactive phosphorus (DRP) in paddy field runoff decreased with time, especially PP. Phosphorus concentration exceeded critical value and resulted to eutrophication, which threatened the water quality security of Chagan Lake. Phosphorus concentration in water recession canal increased with time, and eutrophication with different degrees appeared under high temperature. TP concentration in surface water of paddy field was highly negatively correlated with that in water recession canal, and the correlation coefficients R2(α=0.05)in three paddy fields were 0.850 9, 0.896 4 and 0.915 3, respectively. The pollution load of phosphorus in paddy field with the best irrigation condition was higher, and its pollution risk was the highest. Thus, such fields should be monitored and controlled mainly as the critical source area of phosphorus loss. [Conclusion] The study could provide theoretical foundations for developing saline land rationally, establishing optimal management measure of phosphorus in saline land and controlling phosphorus loss from farmland to protect local water resources.

Research on Air Temperature Variation Characteristics and Trend in Tacheng Prefecture in Xinjiang during 1954-2008

[Objective] The aim was to analyze the changes characteristics of temperature in Tacheng.[Method] By dint of monthly average temperature from 1955 to 2008 in four typical meteorology station,Tacheng,Hebukesai’er,Tuoli and Wusu,the temperature multi-temporal scale characteristics and changes trend in future in Tacheng were expounded by small wave analysis and climate trend coefficient method.[Result] The average temperature in so many years in Tacheng was 5.88 ℃.The annual changes of temperature were relatively stable.The coefficient of changes were between 0.130-0.265.The extreme value was between 1.73-3.79;the sequence distribution of temperature showed plat peak form and the annual average temperature was divergence.The temperature in Tacheng had 5-year,9-year and 14-year period.It was in cold period in 1970 when average temperature was only 3.77 ℃.The 1980s was the warmest age in recent 54 years,reaching 8.10℃.In recent 90s,and comparing with 80s,temperature in Tacheng was decreasing,but still higher than that in 70s.It was forecasted that the temperature in future would increase.The annual average temperature in each area and the average temperature in each season in Tacheng increased significantly,with a range of 1.15-2.05 ℃/10 a.The smallest temperature increase speed in summer was 0.16-0.45 ℃/10 a.The annual average temperature changes speed was 0.40-0.78 ℃/10 a.[Conclusion] The temperature changes in Tacheng had positive corresponding trend toward the climate warming.

Variation Characteristics of the Large-scale Frost in East Region of the Yellow River of Gansu in Recent 40 Years

[Objective]The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.[Method]Based on daily minimum temperature data at 15 meteorological stations over the east region of the Yellow River of Gansu from 1969 to 2008,according to common climatic statistical index of the frost,variation characteristics of the large-scale frost and continuous frost in the east region of the Yellow River of Gansu in recent 40 years were studied.[Result]Since the 1990s,average last frost date in the east region of the Yellow River of Gansu obviously advanced,and first frost date started to obviously postpone.Advancing time of the last frost date was longer than postponing time of the first frost date.Average frost-free period also obviously prolonged.Extremely early first frost date and extremely late last frost date mainly happened in the 1970s and the 1980s.Extremely late first frost date and extremely early last frost date mainly happened after the middle period of the 1990s.Extremely long frost-free period gradually started to appear frequently.In recent 40 years,the continuous frost gradually decreased,and the intensity also declined.[Conclusion]The research was favorable for understanding change characteristics of the frost and climate in the east region of the Yellow River of Gansu,and had important guidance significance for improving prediction capability of the abnormal frost disaster,effectively preventing frost disaster and improving crop yield in the area.

Variation Characteristics of Mass Concentration of Inhalable Particles in Qingdao, China

The geographical condition of Qingdao, China is relatively special;the transport of various inland pollutants, the emissions of marine aerosol and local pollutants will have an impact on the changes of atmospheric aerosol concentration. By using the stability classification method, trajectory clustering analysis and the NOAA HYSPLIT model, the seasonal distribution characteristics of atmospheric inhalable particulate matter concentration in Qingdao, China and its relationship with meteorological conditions, mixed layer height, and the seasonal characteristics of Qingdao pollutant transport were analyzed. The results show that the variation trends of PM2.5 and PM10 were about the same, and there are obvious seasonal differences, which are high in winter and spring, and low in summer and autumn. The concentration of inhalable particulate matter has a negative correlation with temperature, wind speed and relative humidity. The concentration of inhalable particulate matter is distinct in different relative humidity ranges. When the wind speed is less than 3 - 4 m/s, there are more inhalable particles, while the mass concentration shows obvious reduction with the wind speed more than 4 m/s. There is a significant negative correlation between the mass concentration of pollutants and the daily maximum mixed layer height. The larger the concentration of pollutants, the smaller the thickness of the daily largest mixed layer. Conversely, the smaller the mass concentration of pollutants, the larger the thickness of the daily largest mixed layer. The pollutant transport in Qingdao has obvious seasonal characteristics. The air mass in spring, autumn and winter is mainly medium-long distance transport from Mongolia and southern Russia, and medium-short distance transport from Inner Mongolia and northeast of China. The source of air masses in summer is mainly transported from the eastern and sea areas.

Temporal-spatial Variation Characteristics of the Extreme Precipitation Days over South China from 1961 to 2010

[ Objective] The research aimed to analyze temporal-spatial variation characteristics of the extreme precipitation days over South China from 1961 to 2010. [ Method] Based on the daily precipitation data in meteorological stations over South China, extreme precipitation thresholds were determined according to the percentiles distribution for different stations. Temporal-spatial variation characteristics of the extreme precipitation days over South China were studied by the methods of fuzzy clustering, trend coefficient, wavelet analysis and cross spectrum analysis, etc. [ Re- suit] Four sub-regions were identified over South China. They were respectively Nanling area, west Guangxi area, Coast area and Hainan area. Occurrence seasons of the extreme precipitations in each sub-region were significantly different. Extreme precipitation clays in four sub-regions all had increase trends, and those of Nanling area and Coast area were significant. From wavelet analysis and cress spectrum analysis, there were significant periodic variation characteristics. Extreme precipitation days in each sub-region all had significant same-phase evolution trends at the peri- od of 2 -5 years, but backward time length was different. [ Conclusion] The research provided background materials for forecast and influence as- sessment of the extremely heavy precipitation over South China.

Analysis on Variation Characteristics of Natural Precipitation Resources in Panzhihua City

Affected by southwest monsoon moisture and topography redistribution,natural precipitation in Panzhihua had obvious difference in temporal and spatial distribution.By using precipitation data from Renhe station in Panzhihua during 1965-2009,the variation characteristics of annual precipitation,flood season precipitation and seasonal precipitation were analyzed.The results showed that spring precipitation,summer precipitation,flood season precipitation and annual precipitation changed conformably and significantly since 1970s in 20th century,showing increase trend at present,while autumn precipitation showed decrease tendency.From the 10-year running mean of annual precipitation,it was found that the annual variation of precipitation resources in Panzhihua City had its own regularity,and there was a slowly decrease at present.

INTERANNUAL VARIATION CHARACTERISTICS OF EAST HEMISPHERIC CROSS-EQUATORIAL FLOW AND ITS CONCURRENT RELATIONSHIPS WITH TEMPERATURE AND RAINFALL IN CHINA

The NCEP/NCAR global reanalysis data were used to analyze the interannual variation characteristics of the cross-equatorial flow (CEF) and its concurrent relationships with temperature and rainfall in China. The results indicated that CEF changes more in summer than in winter. As the main flow channel in summer, the Somali CEF changes in a way that does not markedly influence the changes in the CEF total except for winter. The summer CEF total has two sudden increases and one sudden decrease during the last century while the winter total has just one decrease. Long-period data show that the correlation between CEF and summer rainfall in China is not very significant, but is different before and after the 1970s, which is due to CEF's close links with the East Asia summer monsoon. Winter CEF's correlation with concurrent winter temperature in northern and southern China varies with the relationship between CEF and sea-level pressure in different areas.

Some Annual Variation Characteristics for the Northern Hemispheric Monthly Mean Precipitation Fields

By the utilization of monthly precipitation data from all stations in the Northern Hemisphere annexed to the 'World Survey of climatology, Vol. 1-15', the distributions of the maximum precipitation months (MPM), the annual relative precipitation (ARP) and the monthly relative precipitation (percent of annual) in January and July are respectively mapped. Moreover the distributions of intermonthly relative precipitation variabilities from January to December are plotted as well. From these figures, the precipitation in the Northern Hemisphere may be classified into three types(continental, oceanic and transitional types) and 17 regions. The precipitation regime may also be divided into two patterns, the global and regional patterns. The global pattern consists of planetary front system and ITCZ and its inter-monthly variation shows the north-and-south shift of the rain belt; the regional pattern consists of the sea-land monsoon and plateau monsoon regime, in which the inter-monthly variation of rain belt shows a east-and-wcst shift.

STUDY ON VARIATION CHARACTERISTICS OF SST OBSERVED IN THE PAST 40 YEARS IN THE COASTAL REGION OF SOUTH CHINA

To study the variation characteristics of SST in coastal south China, observed SST was analyzed for the past 44 years. The results show that the monthly and yearly averaged SST have rising trends, the yearly averaged SST＇s linearity rising rate is 0.12-- 0.19 ℃/decade in the years, the rising extents in winter are higher than those in summer. The variability in winter is larger than that in summer, with the largest in February and March. A majority of significant cold or warm events occurred in winter. A wavelet multiresolution method was used to analyze periodical characteristics of SST in coastal south China, all timescale decomposition series are very similar, and high-frequency decompositions within the year are dominant. Low-frequency decompositions show rising trends since the mid-1970.

Analysis of Relation between Variation Characteristics and Climatic Influencing Factors of Shallow Ground Temperature in Shijiazhuang

Based on the daily observation data of shallow ground temperature, total cloud cover, precipitation, evaporation capacity and frozen soil of 5 stations in Shijiazhuang from 1981 to 2010, using methods such as linear trend and complete correlation coefficient, relation between variation characteristics and climatic influencing factors of shallow ground temperature was analyzed to lay the foundation for studying impact factors of shallow ground temperature and provide references for daily maintenance of automatic observation business. The results showed that fluctuant variability and fluctuant range of mean shallow layer ground temperature in Shijiazhuang became smaller with soil layer being deeper for all years and seasons, and the fluctuant variability was maximal in spring and minimal in winter, while the fluctuant range was maximal in summer and minimal in winter; mean shallow layer ground temperature for all years had a warming trend with an obvious warming trend in winter, and warming range in winter was smaller and the extent was weaker with soil layer being deeper while a cooling trend occurred in summer; there was a coincident trend between total cloud cover at night and shallow ground temperature in winter, and between evaporation capacity and shallow ground temperature in summer, while there was an inconsistent trend between maximum depth of frozen soil, period of freezing weather and shallow ground temperature in winter, and between total cloud cover in the davtime, orecioitation and shallow around temperature in summer.

Variation Characteristics of Low Temperature and Rainy Weather in Guangxi during Spring Sowing Period of Recent 50 Years

[Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data from 1961 to 2010 at 88 meteorological stations in Guangxi,yearly days and end date of low temperature and rainy weather during spring sowing period were carried out statistics.The variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years were analyzed by using linear tendency calculation,phased analysis,Morlet wavelet analysis and correlation analysis.Moreover,the influences of climate warming on days and end date of low temperature and rainy weather in spring sowing period were analyzed.[Result] The average days of low temperature and rainy weather in Guangxi during spring sowing period from 1961 to 2010 was during 3.5-23.2 d.The regional distribution characteristics were that it was more in northeast and mountain zone,and less in southwest and valley.The regional distribution characteristics of end date were that it was late in northeast and mountain zone,and early in southwest and valley.The days of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years presented slight decrease trend,and the end date presented slight advancing trend.The phased variation characteristics of days and end date of low temperature and rainy weather were obvious.The days of low temperature and rainy weather from the early 1980s to metaphase of 1990s was obviously more,and the end date was obviously later.After the 1990s,the days of low temperature and rainy weather was obviously less,and the end date was obviously earlier.The days of low temperature and rainy weather had periodic oscillation signals of 4,6,8,10-14 years.The end date had periodic oscillation signals of 6,12-14 years.The days and end date of low temperature and rainy weather in Guangxi during spring sowing period significantly related to average temperature from middle dekad of February to first dekad of April.The climate warming made that the days of low temperature and rainy weather tended to decrease,and the end date tended to advance.[Conclusion] The research provided reference for further understanding the occurrence rule of low temperature and rainy weather,going after profits and avoiding disadvantages,reasonably arranging production,carrying out correlated research.

Variation Characteristics of Longest Continuous Rainfall Days in Shenyang in Recent 48 Years

[Objective] The aim was to study the variation characteristics of longest continuous rainfall days in Shenyang in recent 48 years. [Method] Based on the data of longest continuous rainfall days in Shenyang from May to September in 1961-2008, the variation characteristics of longest continuous rainfall days in Shenyang in recent 48 years was analyzed by means of one-dimensional linear trend estimation and wavelet analysis method. [Result] In recent 48 years, the longest continuous rainfall days in Shenyang showed decrease trend from May to September except for June in which it showed increased; the total longest continuous rainfall days showed decrease trend, and the maximum value appeared in 1986, while the minimum value could be found in 1997; from periodic variation, the total longest continuous rainfall days had the period of 2-3 years, and there also existed the period of 5-7 years after 1980; the total longest continuous rainfall days were more from the beginning of 1960s to the middle of 1990s and less thereafter. [Conclusion] The study could provide theoretical foundation for the deep research on climate change in Shenyang.

New Understanding of Variation Characteristics of Well Water Level in Majiagou Mine,Tangshan City,Hebei,China

Based on the well water level data in Majiagou Mine in Tangshan City since 2000,it is suggested that the water level rise from 2008-2014 is possibly associated with reduced infiltration caused by less precipitation,together with the effect of less groundwater exploitation. However,the water level rise from 1992-1998 cannot be interpreted properly if we extend the data source back to 1991. After comparing the data with long-term water level data of five wells with different hydro-geological units in Tangshan and Qinhuangdao, the study indicates that the long-term water level variation cannot be only attributed to the effect of less precipitation and the control of groundwater exploitation,but also with the influence of regional stress field change.With the support of regional geological and tectonic information,combined with the comprehensive analysis of CBM data obtained from the coal field,new understandings of the dynamic characteristics of annual variation are obtained.

Variation characteristics of aquifer parameters induced by groundwater source heat pump operation under variable flow

The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.

Analysis on the Variation Characteristics of Temperature and Precipitation in Benxi Area under the Background of Climate Warming

[Objective] The research aimed to study the variation characteristics of temperature and precipitation in Benxi area under the background of climate warming.[Method] Based on the monthly mean temperature and precipitation data of four routine meteorological stations in Benxi area from 1953 to 2010,by using linear tendency rate,linear regression equation,wavelet analysis,Mann-Kendall detection and so on,the variation characteristics of temperature and precipitation under the background of climate warming in the area were analyzed.[Result] The annual average temperature during 1953-2010 in Benxi area presented rise trend,and the linear tendency rate was 0.28 ℃/10 a.It was temperature increase trend in four seasons.The temperature rise rate in winter was the maximum and was the minimum in summer.The annual rainfall presented decrease trend,and the linear tendency rate was-18.16 mm/10 a.Except in spring,it was decrease trend in other seasons.Mann-Kendall mutation detection showed that the mutation of annual average temperature in Benxi area in recent 58 years appeared in 1986.There was no mutation phenomenon in summer.Spring mutation appeared in 1974,and autumn mutation appeared in 1987.Winter mutation was in 1981.The annual and seasonal precipitation didn’t have the mutation phenomenon.The wavelet analysis found that the annual average temperature had the periodic variations of 12-14,5-6 and 2 years in Benxi area in recent 58 years.The annual rainfall had the periodic fluctuations of 8-12,5-6 and 2 years.[Conclusion] The research provided the scientific basis for exploration and sustainable development of the climate resources in the mountain area.

Analysis on the Variation Characteristics of Sunshine Hours in Puyang City

[Objective] The research aimed to analyze the variation characteristics of sunshine hours in Puyang City in recent 51 years.[Method] Based on the monthly sunshine hours in five meteorological stations of Puyang City during 1960-2010,the annual,seasonal and monthly variation trends of sunshine hours,mutation time node were analyzed by using the climate trend coefficient,climate tendency rate,sliding average method,SNR and so on.The objective fact and rule of sunshine variation in Puyang in recent 51 years were revealed.[Result] The annual sunshine hours presented the decline trend in Puyang City in recent 51 years,and the decline range was-14.30 h/a.The seasonal sunshine hours presented the decline trend over the years,and the decline range was during-0.66 and-1.89 h/a.The maximum decline range was-1.89 h/a in summer.The monthly sunshine hours presented the decline trend over the years,and the decline range was during-21.51 and-2.13 h/a.The maximum decline range was-21.51 h/a in July.The annual sunshine hours had one mutation in 1983.The sunshine hours was more in the 1960s and 1970s.In the middle and late periods of 1980s,the sunshine hours was relatively less.[Conclusion] The research provided the guidance value for the adjustment of plantation structure and the transformation of agricultural developed manner in Puyang City.