Estimation of surface air temperature trends over the Russian Federation territory using the quantile regression method

The results are presented of the estimation of surface air temperature variations in different climatically quasi-homogeneous regions of Russia using the nonparametric method of regression analysis (quantile regression). Daily observation records from 517 weather stations were used. The quantile regression technique used for analyzing the trends in long-term series allows obtaining information on trends for the whole range of quantile values from 0 to 1 of dependent variable distributions. Seasonal and regional features of daily minimum, mean, and maximum air temperature trends are considered in a wide range of quantile values. The proposed method that generalizes long-term trends obt ained for groups of stations by quantile regression, is applied to quasi-homogeneous climate regions identified on the territory of Russia.     

Physiographic factors of seasonal distribution of linear trends in air temperature on the Azov-Black sea coast

The seasonal distribution of linear trends in air temperature on the coast of the Black and Azov seas in 1936-2010 is analyzed using the quantile regression method. Monthly mean and median values of temperature as well as 10% and 90% quantiles of average daily values of temperature are considered to describe changes in extreme positive and negative temperature anomalies. It is demonstrated that besides tendencies that are common for all meteorological stations, local features and physiographic location of the stations are of great importance for the distribution of temperature trends.     

Detecting trends that are nonlinear and asymmetric on diurnal and seasonal time scales

Trends in climate time series are often nonlinear and temporally-asymmetric, i.e. the trend is different for different seasons and/or hours of the day. Here a method is developed that allows the nonlinearity and temporal asymmetry of a trend to be investigated simultaneously. First, nonlinear trend components are extracted from a univariate time series, by adapting a nonparametric dimension-reduction method. Then, the nonlinear trend components are substituted into a regression model in which the periodic mean component and the periodic variation in the amplitude of the nonlinear trend are modeled using harmonic functions of the seasonal and diurnal periods. Third, trend patterns in the positive and negative anomalies are investigated, by extending the nonlinear trend model using indicator variables. Fourth, a non-local inferential test is developed to test the statistical significance of the trend patterns. The nonlinear trend model is applied to a simulated time series, as well as to long-term high-resolution temperature records from five Southern Hemisphere sites: Lucas Heights, Sydney Airport, Cape Grim, Macquarie Island and Law Dome. Our method should be generally useful for identifying the effect of both climate-related factors and observation/site-related factors on seasonal and diurnal trends in meteorological data series.     

气候变化趋势分析中自相关的检验与去除

受资料本身、分析方法及未来排放情景假设等因素影响, 气候变暖幅度尚存在较大的不确定性。从分析方法入手, 探讨气象观测序列可能存在的自相关及其对气候变化趋势分析的不确定性影响。引入了Durbin-Watson一阶自相关检验方法对气象观测序列进行检验, 并用Cochrane-Orcutt方法去除存在的自相关。分析发现:浙江省平湖市气温序列存在的自相关放大了该站气温的升温趋势, 并且虚高了气温变化趋势的显著性水平。因此, 对资料序列进行自相关检验与去除是十分必要的。     

Watershed-wide trend analysis of temperature characteristics in Karun-Dez watershed, southwestern Iran

Trend estimation of climatic characteristics for a watershed is required to determine developing compatible strategies related to design, development, and management of water resources. In this study, the trends of the annual maximum (T _max), minimum (T _min), and mean (T _mean) air temperature; temperature anomaly (T _anomaly); and diurnal temperature range (DTR) time series at 13 meteorological stations located in the Karun-Dez watershed were analyzed using the Mann–Kendall and linear regression trend tests. The pre-whitening method was used to eliminate the influence of serial correlation on the Mann–Kendall test. The result showed increasing trends in the T _min, T _mean, and T _anomaly series at the majority of stations and decreasing trend in the T _max and DTR series. A geographical analysis of the trends revealed a broad warming trend in most of the watershed, and the cooling trends were observed only in the southern parts. Furthermore, the geographical pattern of the trends in the T _mean and T _anomaly series was similar, and the T _max data did not show any dominant trend for the whole watershed. This study provides temperature change scenarios that may be used for the design of future water resource projects in the watershed.     

长期预报基本观测资料自动化处理

将微型气象无人驾驶飞机与无线数字影像采集、传输设备相结合,构成了一套微型无人机空中火情监测系统,并开发了相应的地面监测软件.经过地面测试和空中飞行试验证实,该系统运行良好,对于地面火点有较好的探测能力.目前试验系统已具备单架次完成半径30 km以内,面积80～100 km2林区巡护任务的能力,而且这一系统成本低、使用灵活方便,具有良好的应用前景.同时就系统开发中遇到的相关问题和今后的改进方向进行了讨论.     

On climatic fluctuations and climate trends of modern Moscow

Considered are the results of the investigation of climatic fluctuations, supercentury climate trend, and 30-year trends in modern Moscow based on the time series of monthly mean values of air temperature for 1879?C2010. The data of air temperature anomalies in the Northern Hemisphere for the same period were used for the comparison. The computation of characteristics was carried out using the method of singular spectral analysis.     

Climatic trends in the Amazonian area of Ecuador: Classical and multifractal analyses

The climate evolution and change in the Amazonian area is very important at least at a continental scale involving Latin America where more than 550 million people live. The objective of the present study was to investigate, from an environmental perspective, the climatic trends in the Amazonian area of continental Ecuador. We performed both classical and multifractal analyses of these trends on four climatic variables (maximum and minimum temperature, evaporation and evaporation/precipitation ratio). Data were collected from Puyo meteorological station, Pastaza Province, Ecuador. Data sets covered 31 years (from January 1974 to September 2005). Each time series consisted of 380 months.Piecewise regression analyses with breaking point showed two regimes with a cutoff ranging from t = 80 months (maximum and minimum temperature) to t = 133 months for the evaporation pattern (determination coefficient ≥ 0.979) while the multifractal analyses showed an increasing complexity within each climatic variable. All the considered climatic variables showed an increase since 1974 to approximately 1985. After that some type of smoother increase was observed.     

An efficient forward model of the climate controls on interannual variation in tree-ring width

We present a simple, efficient, process-based forward model of tree-ring growth, called Vaganov–Shashkin-Lite (VS-Lite), that requires as inputs only latitude and monthly temperature and precipitation. Simulations of six bristlecone pine ring-width chronologies demonstrate the interpretability of model output as an accurate representation of the climatic controls on growth. Ensemble simulations by VS-Lite of two networks of North American ring-width chronologies correlate with observations at higher significance levels on average than simulations formed by regression of ring width on the principal components of the same monthly climate data. VS-Lite retains more skill outside of calibration intervals than does the principal components regression approach. It captures the dominant low- and high-frequency spatiotemporal ring-width signals in the network with an inhomogeneous, multivariate relationship to climate. Because continuous meteorological data are most widely available at monthly temporal resolution, our model extends the set of sites at which forward-modeling studies are possible. Other potential uses of VS-Lite include generation of synthetic ring-width series for pseudo-proxy studies, as a data level model in data assimilation-based climate reconstructions, and for bias estimation in actual ring-width index series.     

Trends of surface ozone concentrations in germany and their connections with changes in meteorological variables

Changes in daily mean and daily maximum surface ozone concentrations, temperature, and relative humidity are evaluated based on the data of long-term observations (from 11 to 16 years) carried out at eight German stations. For all stations the trends of daily mean surface ozone concentration are statistically significant and positive. The trend values are different and generally range from 0 to 10% per 10 years. The trends of the maximum daily concentration are, on average, approximately 1.5 times less. Noticeable part of trends of the surface ozone concentration is connected with the trends of meteorological variables: temperature, relative humidity, and air mass transport direction. After the account of the influence of the trends of meteorological variables, the trends of the surface ozone concentration at most stations substantially decrease. The highest trend values of daily mean and daily maximum surface ozone concentrations are observed in a cold season; in a warm season, the trend values are much lower, at some stations they are statistically insignificant. A conclusion is made that for a correct revealing of reasons of long-term changes in the surface ozone concentration one should take into account changes in meteorological factors influencing its formation.     

自贡市近50年来气候变化特征分析

本文利用自贡市1955~2006年的气温、降水资料,采用线性倾向估计、累计距平、Mann-Kendall等方法,研究了自贡市近52年来气温、降水的年、季变化特征。结果表明:在全球气候变化背景下,近52年来,自贡年平均气温略上升,年降水量略减少。秋季气候表现为明显的暖干趋势,春季气候则具有明显的变湿趋势。近10年来自贡气候变暖趋势明显。      

基于水分平衡的云南干湿气候评价指标的研究

为了构建具有科学可比性和客观实用性的干湿气候评判指标。基于广义的水分平衡原理, 从干燥度表达式出发, 通过细化参量和参数化处理, 恰当地加入降水有效性和前期气候影响的修正项, 构建了适用于云南高原山地评价气候干湿度的修正表示式; 应用典型相关分析, 找到了一个与气候蒸发量高度相关的特征量ST=S×T(T, S分别为平均气温、 日照时数), 简化了气候干湿指数表达式的重要参量——气候蒸发量的模拟求算, 实现了由实时常规气象要素观测值对气候干湿指数的简易估算。经业务应用, 提出的干湿指数可客观反映非灌溉区农田土壤湿度状况和变化趋势, 对典型春\, 夏季连旱年干雨季转换期的气候干湿空间分布和逐月变化模拟效果良好。     

The Warming of Lake Tahoe

Summary We investigated the effects of climate variability on the thermal structure of Lake Tahoe, California-Nevada, 1970–2002, and with principal components analysis and step-wise multiple regression, related the volume-weighed average lake temperature to trends in climate. We then used a 1-dimensional hydrodynamic model to show that the observed trends in the climatic forcing variables can reasonably explain the observed changes in the lake. Between 1970 and 2002, the volume-weighted mean temperature of the lake increased at an average rate of 0.015 ^∘C yr⁻¹. Trends in the climatic drivers include 1) upward trends in maximum and minimum daily air temperature at Tahoe City; and 2) a slight upward trend in downward long-wave radiation. Changes in the thermal structure of the lake include 1) a long-term warming trend, with the highest rates near the surface and at 400 m; 2) an increase in the resistance of the lake to mixing and stratification, as measured by the Schmidt Stability and Birge Work; 3) a trend toward decreasing depth of the October thermocline. The long-term changes in the thermal structure of Lake Tahoe may interact with and exacerbate the well-documented trends in the lake's clarity and primary productivity.     

陇中黄土高原陆面辐射分量年际变化及其对气候波动的响应

本文利用兰州大学半干旱气候与环境观测站(SACOL站)2006—2012年陆面过程观测资料以及榆中站气象资料,分析了陆面各辐射收支分量对于气候波动的响应,并且研究了地表反照率年际波动变化,讨论了各陆面过程参数对于黄土高原气候背景年际波动的反馈。并且根据黄土高原降水类型将全年分为冬夏半年讨论,以得到更为显著的年际变化特征和相关关系。结果显示,2006—2012年气温降水的趋势与近年来黄土高原暖干化总趋势相吻合。地表浅层土壤湿度和温度都与气温、降水呈现很好的响应。气候因素的综合影响是地表反照率变化波动的原因。通过冬夏半年资料区分探究得到,长波辐射分量与气候要素的相关较短波辐射分量与气候要素的相关性更强。但总体而言,陆面过程对于该地区气候背景波动的响应机制是较为复杂的。     

我国强降雪气候特征及其变化

基于全国气象台站逐日地面降雪观测数据,对我国25°N以北不同气候区强降雪事件的地理分布和年内旬、月变化等气候特征进行分析,并探讨1961—2008年其时间序列演变特征,及1961—2008年和1981—2008年 (气候变暖后) 气候变化趋势。结果表明:强降雪量和强降雪日数在青藏高原东部、新疆和东北北部最多;强降雪强度高值中心出现在云南。东北北部、华北、西北、青藏高原东部强降雪事件多发生于初冬和初春,年内分布呈双峰型;新疆和黄淮地区年内分布呈单峰型,前者多发生在隆冬时节,后者多发生于晚冬;1961—2008年东北北部、新疆、青藏高原东部平均强降雪量和强降雪日数呈明显增加趋势;气候变暖后我国大部年强降雪量增多,强降雪日数增加,强降雪强度增强。     

自贡市近50年来气候变化特征分析

本文利用自贡市1955～2006年的气温、降水资料,采用线性倾向估计、累计距平、Mann-Kendall等方法,研究了自贡市近52年来气温、降水的年、季变化特征。结果表明：在全球气候变化背景下,近52年来,自贡年平均气温略上升,年降水量略减少。秋季气候表现为明显的暖干趋势,春季气候则具有明显的变湿趋势。近10年来自贡气候变暖趋势明显。     

Analysis of recent climatic variations in Castile and Leon (Spain)

This paper reports the results of the analysis of annual mean temperature and precipitation series from 171 meteorological stations distributed over Castile and Leon [Castilla y León in Spanish] in Spain on monthly, seasonal and annual time-scales for a 37-year study period (1961–1997). Various statistical tools were used to detect and characterize significant changes in these series. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, and the statistical significance was determined by means of nonparametric tests. Positive trends of about 0.33 °C in the annual mean temperature were found for the whole period. Mean temperatures increased in spring and winter, the winter trend being statistically significant. The months of December and March also showed significant trends. Decreases in rainfall were found for three seasons (winter, spring and autumn), with statistically significant trends in March. Summer precipitation showed slight increases over the 37-year period. On this basis, the authors consider that the increase in summer precipitation and the decrease in the range of average temperatures between the warmest and the coldest months of the year (continentality), point towards a trend to a more oceanic climate in Castile and Leon.     

Changes of atmospheric circulation in central Europe and their influence on climatic trends in the Czech Republic

This work deals with the influence of changes of atmospheric circulation on observed trends of 11 climatic elements at 21 stations in the Czech Republic in the period 1961–1998. Atmospheric circulation in central Europe is described by the German (Hess-Brezowsky) and Czech-Slovak (Brádka’s) subjective catalogues of synoptic types. In the study period there is a strong downward trend in the occurrence of anticyclonic types in Brádka’s catalogue in all seasons, this trend being most prominent in autumn. Westerly and northwesterly types become more frequent in autumn and winter, less frequent in spring and summer under both classifications. In the Hess-Brezowsky catalogue, the occurrence of anticyclonic types increases in winter, spring, and summer. To assess the effect of circulation changes on observed climate trends we have used the method of “hypothetical” seasonal trends that are calculated from a daily series, constructed by assigning the long-term monthly average of the given climatic element under a specific circulation type to each day classified with this type. The ratio of these circulation-conditioned trends and observed seasonal trends shows that changes in atmospheric circulation are the primary cause of massive winter warming and autumn cooling, which is connected with increasing precipitation and humidity. Summer climate trends are unrelated to changes in atmospheric circulation. Simultaneous use of more circulation classifications for the detection of climatic changes is highly recommended, as the long-term circulation trends depend on the catalogue applied.     

Meteorologically consistent bias correction of climate time series for agricultural models

Conventional bias correction of simulated climate time series for impact models is done separately for climate variables and hence leads to inconsistencies between them. However, agricultural models mostly use several variables, and meteorological consistency is essential. The present work points out meteorological inconsistency due to quantile mapping and describes a new method of consistent bias correction by an optimization approach. Time series of hourly precipitation and global radiation from the regional model REMO5.7 (Run UBA C20/A1B_1) were corrected with site observations from the German Meteorological Service. The results urge to check conventionally corrected series for consistency before using them for multidimensional models. Here, quantile mapping resulted in underestimation of diffuse radiation at hours with precipitation. This deficit was minimized by the developed procedure.