基于Daniel及Mann-kendall检验的辽西北地区降雨量趋势分析

为探索辽西北地区降雨特征及其发生规律,采用辽西北地区5个市21个气象站1952~2006年间的气象资料,应用Daniel及Mann-Kendall检验方法对辽西北地区降雨量的年际变化及季节变化趋势进行分析,并应用Mann-Kendall对降雨量进行突变性检验。分析结果表明:虽然两种方法是从不同时间段对辽西北地区降雨量进行检验,但二者结果基本吻合,整体上辽西北地区降雨量呈下降趋势,且变化比较稳定;辽西北地区虽个别城市在一些年份降雨出现了上升趋势,但整体上还是下降趋势较显著,这与趋势分析结果相似,也与实际情况相符。

Temperature Variation and Mutation Analysis over the Past 59 Years in Shenyang

In this paper,based on the observation data of air temperature during 1951-2009 in Shenyang,the interannual and interdecadal variation of annual average temperature,maximum and minimum temperature in Shenyang were conducted the statistical analysis by means of linear trend estimation and mutation detection by using Mann-Kendall method.As was demonstrated in the results,the annual average temperature,maximum and minimum temperature in Shenyang showed an upward trend,whose linear tendency rate was 0.231,0.181 and 0.218 respectively.The increment trend of annual average temperature,maximum and minimum temperature was extremely clear.The increase in minimum temperature was more significant than that in mean temperature and maximum temperature.The abrupt change point of annual mean temperature in Shenyang appeared in 1981;the abrupt change point of annual mean maximum temperature appeared in 1994;the annual mean minimum temperature underwent mutation in 1978.

福建省2000—2013年气象因子的变化趋势

基于福建省10个气象站2000—2013年的气象观测资料,应用Sen's斜率估计法和Daniel趋势检验法分析了4个气象因子的年际和季节变化趋势及其空间分布,采用Pettitt突变检验法检测突变点的发生.结果表明:在年际和季节变化的趋势中,东南沿海地区的风速显著减弱,西北部地区显著增强;南部地区夏天和秋天的相对湿度显著降低;降水的年际和季节变化不显著;全省气温升高突变集中在2011年;此外,虽然冬天和春天的气温越来越低,夏天气温越来越高,但趋势缓慢不显著,表明福建省气温整体趋于稳定.

Detection of Approximate Potential Trend Turning Points in Temperature Time Series (1941-2010) for Asansol Weather Observation Station, West Bengal, India

Researches are being carried out world-wide to understand the nature of temperature change during recent past at different geographical scales so that comprehensive inferences can be drawn about recent temperature trend and future climate. Detection of turning points in time series of meteorological parameters puts challenges to the researches. In this work, the temperature time series from 1941 to 2010 for Asansol observatory, West Bengal, India, has been considered to understand the nature, trends and change points in the data set using sequential version of Mann-Kendall test statistic. Literatures suggest that use of this test statistic is the most appropriate for detecting climatic abrupt changes as compared to other statistical tests in use. This method has been employed upon monthly average temperatures recorded over the said 70 years for detection of abrupt changes in the average temperature of each of the months. The approximate potential trend turning points have been calculated separately for each month (January to December). Sequential version of Mann-Kendall test statistic values for the months of July and August is significant at 95% confidence level (p 0.05). The average temperature for most of the other months has shown an increasing trend but more significant rise in July and August temperature has been recognized since 1960s.

Trend Analysis of the Mean Annual Temperature in Rwanda during the Last Fifty Two Years

Climate change and global warming are widely recognized as the most significant environmental dilemma the world is experiencing today. Recent studies have shown that the Earth’s surface air temperature has increased by 0.6°C - 0.8°C during the 20th century, along with changes in the hydrological cycle. This has alerted the international community and brought great interest to climate scientists leading to several studies on climate trend detection at various scales. This paper examines the long-term modification of the near surface air temperature in Rwanda. Time series of near surface air temperature data for the period ranging from 1958 to 2010 for five weather observatories were collected from the Rwanda National Meteorological Service. Variations and trends of annual mean temperature time series were examined. The cumulative sum charts (CUSUM) and bootstrapping and the sequential version of the Mann Kendall Rank Statistic were used for the detection of abrupt changes. Regression analysis was performed for the trends and the Mann-Kendall Rank Statistic Test was used for the examination of their significance. Statistically significant abrupt changes and trends have been detected. The major change point in the annual mean temperature occurred around 1977-1979. The analysis of the annual mean temperature showed for all observatories a not very significant cooling trend during the period ranging from 1958 to 1977-1979 while a significant warming trend was furthermore observed for the period after the 1977-1979 where Kigali, the Capital of Rwanda, presented the highest values of the slope (0.0455/year) with high value of coefficient of determination (R2 = 0.6798), the Kendall’s tau statistic (M-K = 0.62), the Kendall Score (S = 328) with a two-sided p-value far less than the confidence level α of 5%). This is most likely explained by the growing population and increasing urbanization and industrialization the country has experienced, especially the Capital City Kigali, during the last decades.

Extreme value analysis of streamflow time series in Poyang Lake Basin,China

Extreme meteorological and hydrological events may cause major disasters and heavy social and economic losses. Therefore, more and more studies have focused on extreme hydro-meteorological events in various climates and geographic regions. Based on nearly 50 years of observed records of the Poyang Lake Basin, the occurrence and changing trends of extreme streamflow indices, including the annual maximum flow, annual peak-over-threshold flows, and low flows, were analyzed for ten hydrological stations. The results indicate that most annual maximum flows occurred from April to July, highly attributed to the Southeast Asian summer monsoons, whereas the annual minimum flows were concentrated between January and February. As for the low flow indices （the annual minimum flow, annual minimum 7-d flow, and annual minimum 30-d flow）, a significant increasing trend was detected in most parts of the Poyang Lake Basin. The trends illustrate the potential effects of climate change and human activities on the hydrological cycle over the Poyang Lake Basin.

Change in rainfall erosivity in the past and future due to climate change in the central part of India

Temporal change in rainfall erosivity varies due to the rainfall characteristic(amount,intensity,frequency,duration),which affects the conservation of soil and water.This study illustrates the variation of rainfall erosivity due to changing rainfall in the past and the future.The projected rainfall is generated by SDSM(Statistical DownScaling Model)after calibration and validation using two GCMs(general circulation model)data of HadCM3(A2 and B2 scenario)and CGCM3(A1B and A2 scenario).The selected study area is mainly a cultivable area with an agricultural based economy.This economy depends on rainfall and is located in a part of the Narmada river basin in central India.Nine rainfall locations are selected that are distributed throughout the study area and surrounding.The results indicate gradually increasing projected rainfall while the past rainfall has shown a declined pattern by Mann–Kendall test with statistical 95%confidence level.Rainfall erosivity has increased due to the projected increase in the future rainfall(2080 s)in comparison to the past.Rainfall erosivity varies from
32.91%to 24.12%in the 2020s,
18.82 to 75.48%in 2050 s and 20.95–202.40%in 2080s.The outputs of this paper can be helpful for the decision makers to manage the soil water conservation in this study area.