Variation Trends of Dust Storms in Relation to Meteorological Conditions and Anthropogenic Impacts in the Northeast Edge of the Taklimakan Desert, China

To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined with dust storm frequency data, and the possible impacts of meteorological and anthropogenic factors on dust storm frequency were analyzed by using regression analysis and PCA (Principal Component Analysis). Results show that the inter-annual dust storm frequency increased gradually. In particular, an increasing trend in recent years, after 2009, is conspicuous. The monthly frequency of dust storms shows higher values between the months of February and May, with the highest mean number of events occurring in April, which accounts for 29% of the annual dust storm frequency. The annual dust storm frequency is positively correlated with wind speed and negatively correlated with precipitation;the monthly dust storm frequency is positively correlated with wind speed, but no significant correlation can be found with precipitation. The relationship between temperature and dust storms is not simply linear, however, a certain correlation with an unremarkable statistical significance can be found between them. Human activities also affect the dynamics of dust storms indirectly via changing vegetation coverage and direct dust emissions. The multivariate analysis further confirmed the association between dust storm frequency and meteorological factors and NDVI. The high loadings of dust storm frequency, wind speed, precipitation and NDVI on a PC indicate that the increased precipitation and NDVI will decrease dust storm frequency, and increased wind speed will increase dust storm frequency.

The trend on runoff variations in the Lhasa River Basin

Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of the two hydrological stations （Lhasa and Tanggya） and the meteorological data of the three meteorological stations （Damxung, Lhasa and Tanggya）. The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows： （1） The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points （around 1970 and the early 1980s）, after which the runoff tended to increase and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year （November to April） and some other months （May, July and September）. （2） The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season.

Analysis on the Climate Variation Characteristics of Frost in Shandong Province

[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.

Winter sea ice albedo variations in the Bohai Sea of China

Sea ice conditions in the Bohai Sea of China are sensitive to large-scale climatic variations. On the basis of CLARA-A1-SAL data, the albedo variations are examined in space and time in the winter（December, January and February） from 1992 to 2008 in the Bohai Sea sea ice region. Time series data of the sea ice concentration（SIC）, the sea ice extent（SIE） and the sea surface temperature（SST） are used to analyze their relationship with the albedo. The sea ice albedo changed in volatility appears along with time, the trend is not obvious and increases very slightly during the study period at a rate of 0.388% per decade over the Bohai Sea sea ice region.The interannual variation is between 9.93% and 14.50%, and the average albedo is 11.79%. The sea ice albedo in years with heavy sea ice coverage, 1999, 2000 and 2005, is significantly higher than that in other years; in years with light sea ice coverage, 1994, 1998, 2001 and 2006, has low values. For the monthly albedo, the increasing trend（at a rate of 0.988% per decade） in December is distinctly higher than that in January and February. The mean albedo in January（12.90%） is also distinctly higher than that in the other two months. The albedo is significantly positively correlated with the SIC and is significantly negatively correlated with the SST（significance level 90%）.

Analysis on the Variation of Rainfall Data from Guilin Weather Station during 1957-2007

[Objective] The research aimed to study the variation of rainfall data from Guilin Weather Station during 1957-2007.[Method] Based on the daily rainfall data in Guilin during 1957-2007,the trend,period and mutation of precipitation in Guilin in 51 years were analyzed by using the trend analysis,wavelet analysis and Mann-Kendall non-parameter statistics test method.[Result] The rainfall in Guilin in 51 years presented the rising trend.The rainfall variation was same in the first,second and third quarters of most years,except in the individual year.The rainfall in the fourth quarter had the decrease trend,and the variation was obvious in each year.It illustrated that the rainfall variation in winter was very unstable and had the decrease trend in recent years.But as a whole,the variation of total rainfall in Guilin wasn’t obvious and had the rise trend.It illustrated that the climate variation in Guilin in 51 years wasn’t obvious.The wavelet analysis showed that the rainfall variation in Guilin had 15-year big period and the small period of 2-3 years.Mann-Kendall non-parameter statistics test showed that the mutation situation of total rainfall in Guilin in 51 years wasn’t obvious.But the mutation situations in the second and third quarters were more.The variation in recent 10 years was the most obvious.Maybe it was affected by the global climate variation.[Conclusion] The research provided the theory basis for analyzing the climate variation in Guilin.

Status-quo of proved oil/gas initially-in-place in China as of 2020 and its variation trend in the past decade

This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oil/gas in China as of 2020 based on statistics.As shown by the results,the proved oil initially-in-place(OIIP),the proved undeveloped OIIP,and the remaining proved TRR of oil in China are mainly distributed in the Bohai Bay,Ordos and Songliao Basins,and those of free gas are mainly in the Ordos,Sichuan,and Tarim Basins.From 2011 to 2020,the largest increment in the proved OIIP,the proved undeveloped OIIP and the remaining proved TRR of oil occurred in the Ordos Basin,followed by the Bohai Bay Basin,while that in the proved gas initially-in-place(GIIP),the proved undeveloped GIIP,and the remaining proved TRR of gas occurred in the Ordos Basin,followed by the Sichuan Basin.In addition,a comprehensive analysis reveals that the petroliferous basins in China with the potential of reserve addition and production growth include the Ordos Basin,the Bohai Bay Basin,the Sichuan Basin,and the Tarim Basin.

利用中值检测方法研究近45年山东极端冷暖天气气候事件(英文)

By using the daily temperature data in 90 meteorological observatories in Shandong Province,the median and a new kind of extreme event detection method which was put forward by Hample,the variation characteristics of extreme cold and warm weather climate events in Shandong Province were detected and analyzed.The results showed that the extreme high temperature days had no obvious variation,and the extreme warm days tended to increase.The extreme cold event decreased obviously and had the obvious inter-decadal variation characteristic.In the 1960s,the extreme cold(warm) event happened frequently,but they both decreased slightly during the 1970s-metaphase of 1980s.After the metaphase of 1990s,the extreme warm event happened frequently,but the extreme cold event decreased sharply.In the spatial distribution,the extreme cold events in most areas of Shandong tended to decrease.But the occurrence frequency variation of extreme warm event presented the radial distribution characteristics that it increased in the eastern coastal zone and decreased in the southwest,northwest of Shandong Province.Under the background that the global climate became warm obviously in the metaphase of 1980s,the positive trend scope of extreme warm event linear variation in Shandong Province obviously became large.The variation of extreme low temperature days in most areas tended to be stable,and the main trend of extreme cold days was still the rapid decrease.

Use of a Land Surface Model to Evaluate the Observed Soil Moisture of Grassland at the Tongyu Reference Site

A land surface model driven by the continuous three-year observed meteorological data with a time interval of 30 minutes at the Tongyu station, a reference site of the Coordinated Enhanced Observing Period （CEOP）, was used to evaluate the observation bias of soil moisture （SM） data and analyze the variation of SM at different time scales. The saline-alkaline soil of the grassland at the Tongyu site makes the measured SM too high, especially in boreal summer of 2003-05. The simulated annual mean SM has the lowest value in 2004 and its three-year variation corresponds to the change of precipitation, whereas the observation shows the increasing trend from 2003 to 2005. Compared to the variation range between -60% and 40% for the anomaly percentage of the simulated daily mean SM during May-October of 2004, the measured data show the higher values more than 40%. The magnitude of the variation trend of the observed daily mean SM in 2003 and 2005 is generally consistent with the simulation. The largest deficiency for the soil moisture observation of the grassland is the overestimated value in the drought year with less precipitation. The simulated monthly mean SM has the lowest value in March due to the large contribution of evaporation relative to precipitation and this phenomenon can not be reproduced in the observation.

Analysis on the Climatic Characteristics of Hail in the South Mountain Area of Ningxia

[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.

Analysis on the Changes of Temperature and Heat Resources in Rural Area of Chaoyang in Western Liaoning

[Objective] The aim was to study the change characteristics of temperature and heat resources in rural area of Chaoyang in western Liaoning. [Method] Based on the data from rural meteorological station in Chaoyang in western Liaoning from 1966 to 2010, the change characteristics of temperature and heat resources in rural area in Chaoyang were analyzed by means of serial correlation and climate tendency method, so as to master its climate situation. [Result] The annual average value of daily average temperature, daily maximum temperature and daily minimum temperature in rural area of Chaoyang in western Liaoning from 1966 to 2010 showed fluctuation variation, and the annual average value of daily maximum temperature increased most obviously with the climatic tendency of 0.328 ℃/10 a and highest significant level, so it played an important role in temperature increase, next came daily average temperature (0.151 ℃/10 a), while there was no obvious decrease in daily minimum temperature. The average of daily maximum temperature in winter half year increased more obviously than that in summer half year, with the climatic tendency of 0.417 and 0.250 ℃/10 a, respectively; the trend of daily average temperature reached low significant level, and there was no obvious variation in daily minimum temperature. In addition, ≥10 ℃ accumulated temperature in rural area of Chaoyang in western Liaoning went up obviously, with the climatic tendency of 42.59 ℃·d/10 a, namely it increased by 192 ℃·d in recent 45 years. [Conclusion] The study could provide climatic reference for the adjustment of agriculture structure and varieties distribution.

Characteristics of gravity signal and loading effect in China

The complex geographical environment in China makes its gravity signals miscellaneous.This work gives a comprehensive representation and explanation in secular trend of gravity change in different regions,the key features of which include positive trend in inner Tibet Plateau and South China and negative trend in North China plain and high mountain Asia（HMA）.We also present the patterns of amplitudes and phases of annual and semiannual change.The mechanism underlying the semiannual period is explicitly discussed.The displacement in three directions expressed in terms of geo-potential spherical coefficients and load Love numbers are given.A case study applied with these equations is presented.The results show that Global Positioning System（GPS） observations can be used to compare with Gravity Recovery and Climate Experiment（GRACE） derived displacement and the vertical direction has a signal-noise-ratio of about one order of magnitude larger than the horizontal directions.

Establishing a Ultraviolet Radiation Observational Network and Enhancing the Study on Ultraviolet Radiation

On the basis of analyzing observational data on solar radiation, meteorological parameters, and total ozone amount for the period of January 1990 to December 1991 in the Beijing area, an empirical calculation method for ultraviolet radiation (UV) in clear sky is obtained. The results show that the calculated values agree well with the observed, with maximum relative bias of 6.2% and mean relative bias for 24 months of 1.9%. Good results are also obtained when this method is applied in Guangzhou and Mohe districts. The long-term variation of UV radiation in clear sky over the Beijing area from 1979 to 1998 is calculated, and the UV variation trends and causes are discussed: direct and indirect UV energy absorption by increasing pollutants in the troposphere may have caused the UV decrease in clear sky in the last 20 years. With the enhancement of people's quality of life and awareness of health, it will be valuable and practical to provid UV forecasts for typical cities and rural areas. So, we should develop and enhance UV study in systematic monitoring, forecasting, and developing a good and feasible method for UV radiation reporting in China, especially for big cities.

Long-Term Changes of the Ultraviolet Radiation in China and its Relationship with Total Ozone and Precipitation

The new version （version 8） TOMS （Total Ozone Mapping Spectrometer） ozone and noontime erythemal ultraviolet （UV） irradiance products are used to analyze their long-term changes in this paper. It is shown that the summer UV irradiance has increased significantly from Central China to the northern and western parts of China, especially in Central China near Chongqing, Shaanxi, and Hubei provinces; whereas the UV irradiance has decreased significantly in the southern part of China, especially in South China. In July, when UV irradiance is at its maximum and hence when the most serious potential damage may happen, the results indicate an increase in the UV irradiance in Central China and the Yangtze River- Huaihe River valley and a decrease in South China and the eastern part of North China. At the same time, the total ozone amount is lower over China in summer with the most serious depletion occurring in Northeast China and Northwest China. It is found that the thinning of the ozone layer is not the main reason for the UV irradiance trend in the eastern and southern parts of China, but that the rainfall and the related cloud variations may dominate the long-term changes of the UV irradiance there. In addition, the future UV irradiance trend in China is also estimated.

GPS time-series and its response to M_S=8.1 Kunlunshan earthquake

In this paper, observation data in 25 GPS reference stations of China have been analyzed by calculating GPS position coordinate time-series with GIPSY. Result shows there is an obvious trend variation in such time-series. The trend variations of time series along the longitude and latitude coordinate reflect the motion of each position in the global-plate, in which the trend variation in the vertical direction reveals some large-scale construction information or reflects the local movement around the positions. The analysis also shows that such time-series have a variation cycle of nearly 1.02 a, but the reason still remains to be further studied. At the end of this paper, response of the time-series to MS=8.1 Kunlunshan earthquake was analyzed, and the seismogenic process of MS=8.1 Kunlunshan earthquake, according to the time proceeding and the feature of anomaly, was divided into 3 phases-changes in blocks with forces, strain accumulation, quick accumulation and slow release of energy. At the initial stage of seismogenic process of MS=8.1 earthquake and at the imminent earthquake, coseismic process as well as during the post earthquake recovery, anomaly in vertical direction is always in a majority. The anomalous movement in vertical direction at the initial stage resulted in a blocking between faults, while at the middle stage of seismogenic process, the differential movement between blocks are in a majority, which is the major reason causing energy accumulating at the blocking stage of faults.

Influence of Climate Warming on the Agriculture in Shenbei New District of Shenyang

[Objective] The research aimed to study the influence of climate warming on the agriculture in Shenbei New District of Shenyang in recent 38 years.[Method] Based on the temperature data in Shenbei New District of Shenyang during 1971-2008,by using the conventional statistical method,the variation trends of temperature and active accumulated temperature in Shenbei New District under the climate warming environment were analyzed,and the influence of climate warming on the agriculture was discussed.[Result] The annual average temperature,annual average maximum temperature,annual averageminimum temperature and ≥ 0℃,≥ 10℃ active accumulated temperatures which were passed stably in Shenbei New District in recent 38 years all showed the obvious rising trend.The climate tendency rates were respectively 0.4,0.3,0.1℃/10 a and 79.1,76.7℃·d/10 a.They all showed the declining trend in the coldest December,January and the rising trend in other months.The rising range of maximum temperature was bigger than that ofminimum temperature,and the rising range in summer was bigger than that in winter.The analysis result was different from that of many scholars.When the temperatures rose,and the heat resources increased,the agricultural cropping index improved,and the cultivated boundary of mid-late maturity variety moved northward.The industrialized agriculture developed quickly.Meanwhile,the risks of drought and flood disasters increased,and the insect pest aggravated.[Conclusion] The research provided the scientific basis for improving the cognizance about the influence of climate warming on the agricultural production and strengthening the strain capacity of local agricultural production adapting the climate variation.

A PRELIMINARY STUDY OF SNOW MASS VARIATIONS IN CHINA OVER THE PAST 30 YEARS

Daily snow data for 2300 climate stations covering the period from 1951 through 1980 have been used to monitor and diagnose secular variations,year-to-year fluctuations,and the spatial characteristics of snow variation trends in China.An examination of time series reveals that there is a strong teleconnction to ENSO,to major volcanic eruptions, as well as to the CO_2-induced warming.The country-wide snow mass variations are positively correlated with global mean temperature,increasing during the current warming period and decreasing during the recent cooling period prior to the mid 1960s.A synchronous relationship exists between El Nino/Southern Oscillation and snowy winter in China. The year-to-year snow fluctuations seem to be generally out of phase with volcanic activity.The anomaly map shows that snow mass increased in high altitudes and moist regions,while it decreased in arid lowland and the southern bounda- ry zone during the warming period.The potential CO_2-induced changes in snow mass will further aggravate the regional differentiation between high mountains and lowlands,between moist and arid regions.The number of snow cover days will decrease in the northern lowlands,and snowfall will increase in the Qinghai-Xizang Plateau,high mountains,and the lower reaches of the Changjiang(Yangtze)River.

Crystal-field analyses for trivalent lanthanide ions in LiYF_4

Based on the completely parametric crystal-field model, the energy level parameters, including free-ion parameters and crystal-field parameters, obtained by fitting the experimental energy level data sets of Ln^（3＋） in LiYF_4 were systematically analyzed. The results revealed that the regular variation trends of the major parameters at relatively low site symmetry still existed. The g factors of ground states were calculated using the parameters obtained from least-squares fitting. The results for Ce^（3＋）, Nd^（3＋）, Sm^（3＋）, Dy^（3＋） and Yb^（3＋） were in good agreement with experiment, while those of Er^（3＋） deviated from experiment dramatically. Further study showed that the g factors depended strongly on B_4~6, and a slightly different B_4~6 value of -580cm^（-1） led to g factors agreeing well with the experimental values.

Quantitative estimation of the impact of precipita- tion and human activities on runoff change of the Huangfuchuan River Basin

The runoff of some rivers in the world especially in the arid and semi-arid areas has decreased remarkably with global or regional climate change and enhanced human activities. The runoff decrease in the arid and semi-arid areas of northern China has brought severe problems in livelihoods and ecology. To reveal the variation characteristics, trends of runoff and their influencing factors have been important scientific issues for drainage basin man- agement. The objective of this study was to analyze the variation trends of the runoff and quantitatively assess the contributions of precipitation and human activities to the runoff change in the Huangfuchuan River Basin based on the measured data in 1960-2008. Two inflection points （turning years） of 1979 and 1998 for the accumulative runoff change, and one inflection point of 1979 for the accumulative precipitation change were identified using the methods of accumulative anomaly analysis. The linear relationships between year and ac- cumulative runoff in 1960-1979, 1980-1997 and 1998-2008 and between year and accu- mulative precipitation in 1960-1979 and 1980-2008 were fitted. A new method of slope change ratio of accumulative quantity （SCRAQ） was put forward and used in this study to calculate the contributions of different factors to the runoff change. Taking 1960-1979 as the base period, the contribution rate of the precipitation and human activities to the decreased runoff was 36.43% and 63.57% in 1980-1997, and 16.81% and 83.19% in 1998-2008, re- spectively. The results will play an important role in the drainage basin management. More- over, the new method of SCRAQ can be applied in the quantitative evaluation of runoff change and impacts by different factors in the river basin of arid and semi-arid areas.

Aridity trend and response to vegetation restoration in the loess hilly region of northern Shaanxi Province

Detecting variation trend in dry-wet conditions can provide information for devel- oping strategic measures to mitigate the impacts of global warming, particularly in dry regions Taking the hilly region of northern Shaanxi on the Loess Plateau as a case area, this study analyzed the trend of aridity variation during 1981-2012, and explored the effect of vegetation restoration promoted by the Grain-for-Green （GFG） program implemented in 1999. The re- sults indicated that the aridity in the region was non-significantly increased by 0.88% per year during 1981-2012, showing a drying trend. This drying trend and amplitude were changed by the influence of vegetation restoration promoted by the GFG program, based on two findings. The first one was that the aridity variation tended to increase during 1981-1999 while it turned to decrease during 2000-2012, with the regional mean relative change rate changed from 2.45% to -1.06%. This distinction was more remarkable in the loess gully region, where the vegetation was improved more obviously. The second one was that the mean vegetation coverage as indicated by EVI increased by 0.90% to 4.32% per year at county level, while the aridity decreased by 0.14% to 2.32% per year during 2000-2012. The regression analysis using the mean county data indicated that the change rate of aridity was negatively related to that of EVI with the coefficient of determination （R2） of 0.56, illustrating that around half of the aridity decline was explained by the EVI change. The mechanism of this effect was compli- cated, but it was found that the wind speed decline induced by the vegetation improvement could be an important contributor. It is concluded that the region became drier during 1981-2012, but the eco-restoration reduced the drying speed. However, this conclusion is involved in uncertainties, and further study based on experiments is needed to confirm the effect of the GFG-promoted vegetation restoration.