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1.
Two approaches of statistical downscaling were applied to indices of temperature extremes based on percentiles of daily maximum and minimum temperature observations at Beijing station in summer during 1960-2008. One was to downscale daily maximum and minimum temperatures by using EOF analysis and stepwise linear regression at first, then to calculate the indices of extremes; the other was to directly downscale the percentile-based indices by using seasonal large-scale temperature and geo-potential height records. The cross-validation results showed that the latter approach has a better performance than the former. Then, the latter approach was applied to 48 meteorological stations in northern China. The cross-validation results for all 48 stations showed close correlation between the percentile-based indices and the seasonal large-scale variables. Finally, future scenarios of indices of temperature extremes in northern China were projected by applying the statistical downscaling to Hadley Centre Coupled Model Version 3 (HadCM3) simulations under the Representative Concentration Pathways 4.5 (RCP 4.5) scenario of the Fifth Coupled Model Inter-comparison Project (CMIP5). The results showed that the 90th percentile of daily maximum temperatures will increase by about 1.5℃, and the 10th of daily minimum temperatures will increase by about 2℃ during the period 2011-35 relative to 1980-99. 相似文献
2.
Luciano Massetti 《Theoretical and Applied Climatology》2014,117(3-4):511-519
Long and complete climatic data series are a fundamental resource for scientific research on climate change. Data quality is important, and missing value or data gap management is a key process that must be dealt with carefully to produce reliable datasets. Although a large variety of techniques are available for gap-filling, a widespread strategy is to consider a dataset reliable if the rate of missing data is below a given threshold. However this strategy varies from study to study. The aim of this paper is to analyze the impact of missing daily values on the estimation of monthly average temperature indices. The relationship between the error of the estimate and the presence of random or consecutive missing values, as well as data series autocorrelation is also analyzed. A theoretical, a linear and a nonlinear model to estimate the maximum error at the 95 % confidence interval are tested on data series provided by national and worldwide networks of stations. Consecutive missing values have an important effect on error estimation due to autocorrelation of temperature data series. On our dataset, the mean and standard deviation of the error for five consecutive missing values (0.27?±?0.05 °C) on a normalized daily series (σ?=?1) was higher than for five random missing values (0.14?±?0.006 °C). A nonlinear model taking into account the number of consecutive missing values is able to estimate the error and its performance is less affected by the presence of consecutive missing values than the other proposed models. 相似文献
3.
X. Lana M. D. Martínez A. Burgueño C. Serra 《Theoretical and Applied Climatology》2009,97(1-2):135-150
Spatial patterns and statistical models for hot and cold events affecting Catalonia (NE Spain) are obtained from series of daily maximum and minimum temperatures recorded at 65 meteorological stations throughout the period 1950–2004. The study is based on the crossing theory, taking care that daily temperatures are normally distributed and previous data treatments (removal of trends and periodicities) assure their stationary character. With the aim of facilitating comparisons among different thermometric records, hot and cold events are defined as large departures, given in standard deviations, of daily temperatures from daily averages. From the statistical point of view, the assumption of a normal distribution of the initial date of the events is questionable and a simple assignment of hot events to summer and cold events to winter must be discarded according to the averaged initial dates and their standard deviations. The event magnitudes, defined as the absolute value of their maximum departures, follow an exponential distribution and event lengths can be modelled by an autoregressive Markov process with a Gaussian noise component. The number of events per year fits a Poisson distribution well only for high departures and the whole number of hot and cold events decays exponentially with the increasing departure for every temperature series. This property permits an estimation of the expected maximum departure for every thermometric station during the recording period. Even though spatial features observed for the number of events, their mean initial date, average event magnitude and average event length depict quite complex patterns due to the orography of the country and the vicinity to the Mediterranean Sea, the results obtained improve the knowledge on the hot and cold events in Catalonia. 相似文献
4.
Ernest M. Agee 《Climatic change》1982,4(4):399-418
A diagnostic study of 80 yrs(1901–80) of surface temperatures collected at West Lafayette, Indiana, has been found to be in
tune with the global trend and that for the eastern two-thirds of the United States, namely, cold at the turn of the century,
warming up to about 1940, and then cooling to present. The study was divided into two cold periods (1901–18, 1947–80) and
a warm period (1919–46), based on the distribution of annual mean temperature. Decadal mean annual temperatures ranged from
10 °C in period I to 12.2 °C in period II, to 9.4 °C during the present cold period. Themean annual temperature for the 80 yr ranged from the coldest of 8.7 °C in 1979 to the warmest of 13.6 °C in 1939. Thedaily mean temperature for the entire 80-yr ranged from -4.7 °C on 31 January to 25.1 °C on 27 July. Thecoldest daily mean was -26.7 °C on 17 January, 1977, and thewarmest daily mean was 35 °C on 14 July, 1936. The range of values for thedaily mean maximum temperatures was -.2 °C on 31 January to 31.4 °C on 27 July. Corresponding values for thedaily mean minimum are -9.2 °C on 31 January and 18.7 °C on 27 July. The all-time extreme temperatures are -30.6 °C on 26 February, 1963 and
43.9 °C on 14 July, 1936.
Climatic variability has been considered by computing the standard deviations of a) the daily mean maximum and minimum temperature
per year, and b) the daily mean maximum and minimum temperatures for each day of the year for the 80-yr period. These results
have shown that there is more variability in the daily mean maximum per year than in the daily mean minimum, for each year
of the 80-yr period. Also the variability for both extremes has been greater in each of the two cold periods than in the warm
period. Particularly noticeable has been theincrease in the variability of the daily mean minima per year during the current cooling trend. Further, it has been determined that
the variability in the daily mean maxima and minima for each day of the year (based on the entire 80 yrs is a) two times greater
in the winter than in the summer for both extremes, and b) about the same for each in the summer, greater for daily maximum
in the spring and fall, but greater for the daily minimum during the winter. The latter result is undoubtedly related to the
effect of snow cover on daily minimum temperatures.
An examination of daily record maximum and minimum temperatures has been made to help establish climatic trends this century.
For the warm period, 175 record maxima and 68 record minima were set, compared to 213 record minima and 105 record maxima
during the recent cold period. For West Lafayette, the present climatic trend is definitely one of extreme record-breaking
cold. Evidence has also been presented to show the substantial increases in snowfall amounts in the lee regions of the Great
Lakes during the present cold period, due to the lake-induced snow squalls associated with cold air mass intrusions. The possible
impact of the cooling trend on agricultural activities has also been noted, due to a reduced growing season. 相似文献
5.
Extreme normalised residuals, defined as departures from the average values, of 65 daily maximum, T max, and minimum, T min, temperature series recorded in Catalonia (NE Spain) during 1950–2004 are analysed. Similarly to the sampling strategies applied to long dry spells, the partial duration series (PDS) offer some advantages in comparison with the annual extreme series. Instead of using a common percentile threshold for all temperature series, PDS are chosen according to the mean excess plot procedure. Series of extreme residuals are modelled, in terms of the L-moments formulation, by the generalised Pareto distribution. Extreme residuals of T max and T min are estimated for return periods ranging from 2 to 50 years and their spatial distribution is represented for selected return periods of 2, 5, 10, 25 and 50 years. Two daily extreme temperatures events, a hot episode (in August) and a cold episode (in February), are simulated taking into account the average T max (T min) for a day in August (February), their standard deviations and the extremes for a 50-year return period. Both simulations are compared with outstanding real episodes recorded on August 13th 2003 and February 11th 1956. Additionally, a spatial regionalisation of Catalonia in several clusters, in terms of the extreme residuals for return periods from 2 to 50 years, is done. A principal component analysis is applied to the extreme residual curves characterising every temperature series and, using as variables the principal components, the regionalisation is obtained by applying the average linkage clustering algorithm. Finally, each cluster is characterised by its average extreme residual curve for return periods ranging from 2 to 50 years at 1-year interval. 相似文献
6.
石家庄城市与郊县站地面平均最低、最高气温差异 总被引：3，自引：0，他引：3
应用石家庄地区17个站1955—2006年逐日最低、最高气温资料,统计分析了16个郊县站与石家庄市区站最低、最高气温的差值。结果表明:各郊县站年平均最低、最高气温均比石家庄市站低,最低气温偏低0.17～2.07℃,16个站平均偏低1.02℃;最高气温偏低0.01～0.55℃,16个站平均偏低0.28℃。郊县站平均最低气温偏低程度在冬季更明显,1月平均达到1.69℃,夏季偏低程度比较弱,但最弱的7月也有0.49℃;最高气温的偏低程度也在冬季明显,但季节性差异没有最低气温大。不论最低气温,还是最高气温,各县(市)站与石家庄市区站之间的差异均存在明显的随时间增大现象,最低气温20世纪90年代初以来增大尤其明显。石家庄市区站地面最低、最高气温记录反映出明显的城市热岛效应影响。 相似文献
7.
Erik Kjellström Lars Bärring Daniela Jacob Richard Jones Geert Lenderink Christoph Schär 《Climatic change》2007,81(1):249-265
Probability distributions of daily maximum and minimum temperatures in a suite of ten RCMs are investigated for (1) biases compared to observations in the present day climate and (2) climate change signals compared to the simulated present day climate. The simulated inter-model differences and climate changes are also compared to the observed natural variability as reflected in some very long instrumental records. All models have been forced with driving conditions from the same global model and run for both a control period and a future scenario period following the A2 emission scenario from IPCC. We find that the bias in the fifth percentile of daily minimum temperatures in winter and at the 95th percentile of daily maximum temperature during summer is smaller than 3 (±5°C) when averaged over most (all) European sub-regions. The simulated changes in extreme temperatures both in summer and winter are larger than changes in the median for large areas. Differences between models are larger for the extremes than for mean temperatures. A comparison with historical data shows that the spread in model predicted changes in extreme temperatures is larger than the natural variability during the last centuries. 相似文献
8.
Summer mean daily temperature extremes in Svalbard Lufthavn (Central Spitsbergen) in the period 1975–2010 and daily pressure patterns and directions of air circulation conducive to their occurrence were analyzed. Positive (negative) extremes of daily mean temperatures in the summer were determined as higher (lower) than or equal to the value of the 90th (10th) percentile. The annual number of selected days shows a great year-to-year variability, although the annual number of extremely low mean daily temperature (≤1.3 °C) was decreasing in the 1976–2010 period, with a rate of about 4 days per decade. At the same time, the number of days with extremely high mean daily temperatures (≤8.2 °C) was increasing with a rate of about 2 days per decade. The summer pressure patterns and the air circulation conditions have an impact on the occurrence of the air mean daily temperature extremes. Namely, anticyclones spreading east to the Svalbard Archipelago, accompanied by the Icelandic Low, cause the air inflow from the southerly direction and positive mean daily temperature extremes. A cyclonal system spreading east or southeast towards the archipelago, together with a high-pressure ridge over the North Atlantic, indicates the northern air flow and negative mean daily temperature extremes in summer. The results obtained in this study prove that the summer air temperature in the Atlantic region of the Arctic is partly controlled by air circulation, and despite the intensity and stability of the summer cyclones and anticyclones being weaker than in the winter, their position strongly determines the occurrence of mean daily temperature extremes in the summer. 相似文献
9.
Weather and climate extremes are often associated with substantial adverse impacts on society and the environment. Assessment of changes in extremes is of great and broad interest. This study first homogenizes daily minimum and maximum surface air temperatures recorded at 146 stations in Canada. In order to assess changes in one-in-20 year extremes (i.e., extremes with a 20-year return period) in temperature, annual maxima and minima of both daily minimum temperatures and daily maximum temperatures are derived from the homogenized daily temperature series and analyzed with a recently developed extreme value analysis approach based on a tree of generalized extreme value distributions (including stationary and non-stationary cases). The procedure is applied to estimate the changes over the period 1911 to 2010 at 115 stations, located mainly in southern Canada, and over the period 1961 to 2010 at 146 stations across Canada (including 37 stations in the North). The results show that warming is strongest for extreme low temperature and weakest for extreme high temperature and is much stronger in the Canadian Arctic than in southern Canada. Warming is stronger in winter than in summer and stronger during nighttime than daytime of the same season. 相似文献
10.
11.
Earth surface temperatures are changing worldwide together with the changes in the extreme temperatures. The present study investigates trends and variations of monthly maximum and minimum temperatures and their effects on seasonal fluctuations at different climatological stations of Maharashtra and Karnataka states of India. Trend analysis was performed on annual and seasonal mean maximum temperature (TMAX) and mean minimum temperature (TMIN) for the period 1969 to 2006. During the last 38 years, an increase in annual TMAX and TMIN has occurred. At most of the locations, the increase in TMAX was faster than the TMIN, resulting in an increase in diurnal temperature range. At the same time, annual mean temperature (TM) showed a significant increase over the study area. Percentiles were used to identify extreme temperature indices. An increase in occurrence of warm extremes was observed at southern locations, and cold extremes increased over the central and northeastern part of the study area. Occurrences of cold wave conditions have decreased rapidly compared to heat wave conditions. 相似文献
12.
The influence of interpolation and station network density on the distributions and trends of climate variables in gridded daily data 总被引：4，自引：1，他引：3
We study the influence of station network density on the distributions and trends in indices of area-average daily precipitation
and temperature in the E-OBS high resolution gridded dataset of daily climate over Europe, which was produced with the primary
purpose of Regional Climate Model evaluation. Area averages can only be determined with reasonable accuracy from a sufficiently
large number of stations within a grid-box. However, the station network on which E-OBS is based comprises only 2,316 stations,
spread unevenly across approximately 18,000 0.22° grid-boxes. Consequently, grid-box data in E-OBS are derived through interpolation
of stations up to 500 km distant, with the distance of stations that contribute significantly to any grid-box value increasing
in areas with lower station density. Since more dispersed stations have less shared variance, the resultant interpolated values
are likely to be over-smoothed, and extreme daily values even more so. We perform an experiment over five E-OBS grid boxes
for precipitation and temperature that have a sufficiently dense local station network to enable a reasonable estimate of
the area-average. We then create a series of randomly selected station sub-networks ranging in size from four to all stations
within the E-OBS interpolation search radii. For each sub-network realisation, we estimate the grid-box average applying the
same interpolation methodology as used for E-OBS, and then evaluate the effect of network density on the distribution of daily
values, as well as trends in extremes indices. The results show that when fewer stations have been used for the interpolation,
both precipitation and temperature are over-smoothed, leading to a strong tendency for interpolated daily values to be reduced
relative to the “true” area-average. The smoothing is greatest for higher percentiles, and therefore has a disproportionate
effect on extremes and any derived extremes indices. For many regions of the E-OBS dataset, the station density is sufficiently
low to expect this smoothing effect to be significant and this should be borne in mind by any users of the E-OBS dataset. 相似文献
13.
为了解ECMWF高分辨率数值预报模式(以下简称“EC”)对广安地区气温的预报性能,提高预报质量。利用EC气温预报产品,对2015～2017年广安地区最低(高)气温进行预报性能检验。结果表明:EC模式预报最低气温,正确率较高;预报最高气温,正确率波动大,随月份呈明显的“V”型变化,盛夏7、8月最低。预报误差随时效延长,略有增大;最低气温误差小于最高气温误差;最低气温误差各月无明显差异,最高气温误差在盛夏7、8月最大。最低气温预报效果区域差异不明显;最高气温预报效果受地形影响较大。根据订正指标,进行气温订正预报,可有效提升预报正确率。EC模式预报高温时的最高气温偏小,经过订正后,各站各时效正确率均明显提高,正确率提升20.6～91.3%,具有较高的参考价值。 相似文献
14.
北京地区城郊极端温度事件的变化趋势及差异分析 总被引：1，自引：0，他引：1
利用北京地区城郊16个气象观测站1979～2008年逐日平均、最高和最低温度的均一化资料,分析了近30年北京地区城、郊区极端温度事件发生频次(强度)的变化趋势,并对比了城郊差异以及城市热岛强度对城郊差异的影响.研究结果显示:从发生频次来看,近30年城区极端低温事件的减小幅度[5.94 d (10 a)-1]高于郊区的减小幅度[-5.28 d (10 a)-1],而极端高温事件的增加幅度在城区[4.33 d (10 a)-1]和郊区[4.42 d (10 a)-1]之间差别不大,定量化的诊断结果进一步证明了城区和郊区在极端温度事件发生频次上的差别很小.从发生强度来看,近30年城区极端温度事件的年平均发生强度明显高于郊区,但在变化趋势上,城区极端低温事件的减弱幅度略高于极端高温事件的增强幅度,相差0.042℃(10 a)-1,而在郊区极端低温事件的减弱幅度却略低于极端高温事件的增强幅度,相差0.052℃(10 a)-1.城郊差异的定量化分析结果表明,极端温度事件在城区强度一般大于郊区强度,城区与郊区强度差值均为正值(除1982年和1985年极端高温事件强度差值为负).热岛强度与极端温度事件城郊差异的相关性统计发现,极端温度事件发生频次和发生强度在城郊之间的差别与热岛强度均没有明显的相关特征,该结果说明城市热岛效应对北京超大城市市区和郊区影响基本一致,其差异性是有限的. 相似文献
15.
Simon J. Brown James M. Murphy David M. H. Sexton Glen R. Harris 《Climate Dynamics》2014,43(9-10):2681-2705
A methodology is presented for providing projections of absolute future values of extreme weather events that takes into account key uncertainties in predicting future climate. This is achieved by characterising both observed and modelled extremes with a single form of non-stationary extreme value (EV) distribution that depends on global mean temperature and which includes terms that account for model bias. Such a distribution allows the prediction of future “observed” extremes for any period in the twenty-first century. Uncertainty in modelling future climate, arising from a wide range of atmospheric, oceanic, sulphur cycle and carbon cycle processes, is accounted for by using probabilistic distributions of future global temperature and EV parameters. These distributions are generated by Bayesian sampling of emulators with samples weighted by their likelihood with respect to a set of observational constraints. The emulators are trained on a large perturbed parameter ensemble of global simulations of the recent past, and the equilibrium response to doubled CO2. Emulated global EV parameters are converted to the relevant regional scale through downscaling relationships derived from a smaller perturbed parameter regional climate model ensemble. The simultaneous fitting of the EV model to regional model data and observations allows the characterisation of how observed extremes may change in the future irrespective of biases that may be present in the regional models simulation of the recent past climate. The clearest impact of a parameter perturbation in this ensemble was found to be the depth to which plants can access water. Members with shallow soils tend to be biased hot and dry in summer for the observational period. These biases also appear to have an impact on the potential future response for summer temperatures with some members with shallow soils having increases for extremes that reduce with extreme severity. We apply this methodology for London, using the A1B future emissions scenario to obtain projections of the 50 year return values for the 20 year period centred on 2050. We obtain 10th to 90th percentile ranges of 35.9–42.1 °C for summer daily maximum temperature, 35.5–52.4 mm for summer daily rainfall and 79.2, 97.0 mm for autumn 5 day total rainfall, compared to observed estimates for 1961–1990 of 35.7 °C, 42.1 and 78.4 mm respectively. 相似文献
16.
Summary A principal component analysis has been performed on the monthly means of the daily extremes of the air temperature at the thermometric network of Belgium. For both the maximum and the minimum temperatures, two components are found to have a climatological significance, the first one giving the common seasonal variation. For the maximum, the second component depends directly on the proximity of the sea, while for the minimum, the second component gives the correction due partly to the proximity of the sea and partly to the site configuration of the station (plateau or valley). In both cases, the variance explained by the two components amounts to or exceeds 99.9% of the total variance.With 4 Figures 相似文献
17.
Huaijun Wang Yaning Chen Shi Xun Dongmei Lai Yuting Fan Zhi Li 《Theoretical and Applied Climatology》2013,112(1-2):15-28
There has been a paucity of information on trends in daily climate and climate extremes, especially for the arid region. We analyzed the changes in the indices of climate extremes, on the basis of daily maximum and minimum air temperature and precipitation at 59 meteorological stations in the arid region of northwest China over the period 1960–2003. Twelve indices of extreme temperature and six indices of extreme precipitation are examined. Temperature extremes show a warming trend with a large proportion of stations having statistically significant trends for all temperature indices. The regional occurrence of extreme cool days and nights has decreased by ?0.93 and ?2.36 days/decade, respectively. Over the same period, the occurrence of extreme warm days and nights has increased by 1.25 and 2.10 days/decade, respectively. The number of frost days and ice days shows a statistically significant decrease at the rate of ?3.24 and ?2.75 days/decade, respectively. The extreme temperature indices also show the increasing trend, with larger values for the index describing variations in the lowest minimum temperature. The trends of Min Tmin (Tmax) and Max Tmin (Tmax) are 0.85 (0.61) and 0.32 (0.17)?°C/decade. Most precipitation indices exhibit increasing trends across the region. On average, regional maximum 1-day precipitation, annual total wet-day precipitation, and number of heavy precipitation days and very wet days show insignificant increases. Insignificant decreasing trends are also found for consecutive dry days. The rank-sum statistic value of most temperature indices exhibits consistent or statistically significant trends across the region. The regional medians after 1986 of Min Tmin (Tmax), Max Tmin (Tmax), warm days (nights), and warm spell duration indicator show statistically more larger than medians before 1986, but the frost days, ice days, cool days (nights), and diurnal temperature range reversed. The medians of precipitation indices show insignificant change except for consecutive dry days before and after 1986. 相似文献
18.
As global warming is scientifically and widely accepted, its impacts at regional scales are raising many questions for wine producers. In particular, climate parameters, especially temperature, play a decisive role in vine growth and grape ripening. An overview of expected climate change in terms of bioclimatic indexes (Winkler and Huglin) and thermal extremes in the wine-producing region of Champagne is presented. A variable-grid atmospheric general circulation model, ARPEGE-Climate, with a local zoom at 50 km over the area of interest, is used to investigate potential future changes in thermal extremes and bioclimatic indexes. Changes in daily maximum and minimum temperatures at key stages are discussed for three emission scenarios (B1, A1B, A2) that are currently used in studies of impacts of climate change. Model outputs are analyzed and critically assessed for a control period (1971–2000) and for changes in extreme events in relation to future scenarios, such as a decrease in extreme low temperatures in spring (April) during bud break and an increase in extreme high temperatures in summer, associated with more frequent heat waves during ripening. 相似文献
19.
Accelerated climate change and its potential impact on Yak herding livelihoods in the eastern Tibetan plateau 总被引：1，自引：0，他引：1
Michelle A. Haynes King-Jau Samuel Kung Jodi S. Brandt Yang Yongping Donald M. Waller 《Climatic change》2014,123(2):147-160
The Tibetan Plateau has experienced rapid warming like most other alpine regions. Regional assessments show rates of warming comparable with the arctic region and decreasing Asian summer monsoons. We used meteorological station daily precipitation and daily maximum and minimum temperature data from 80 stations in the eastern Tibetan Plateau of southwest China to calculate local variation in the rates and seasonality of change over the last half century (1960–2008). Daily low temperatures during the growing season have increased greatly over the last 24 years (1984–2008). In sites of markedly increased warming (e.g., Deqin, Yunnan and Mangya, Qinghai), daily and growing season daily high temperatures have increased at a rate above 5 °C/100 years. In Deqin, precipitation prior to the 1980s fell as snow whereas in recent decades it has shifted to rain during March and April. These shifts to early spring rains are likely to affect plant communities. Animals like yaks adapted to cold climates are also expected to show impacts with these rising temperatures. This region deserves further investigation to determine how these shifts in climate are affecting local biodiversity and livelihoods. 相似文献
20.
Simon J. Mason 《Climatic change》2004,62(1-3):155-187
The climatologies of daily precipitation and of maximum and minimum temperatures over western North America are simulated using stochastic weather generators. Two types of generator, differentiated only by their method of modeling precipitation occurrence, are investigated. A second-order Markov model, in which the probability of the occurrence of precipitation is modeled as contingent upon its occurrence on the previous two days, is compared with a spell-length model, in which mass functions of wet- and dry-spell lengths are modeled. Both models are able to reproduce the observed annual and monthly climatology in the region to a high degree of accuracy. However, there is considerable over-dispersion in annual precipitation, resulting primarily from an underestimation in the interannual variability of precipitation intensity. The interannual variability of temperatures is similarly underestimated, and is most severe for minimum temperatures. There is a severe problem in estimating minimum temperature extremes, which can be attributed to the negatively skewed distribution of daily minimum temperatures. Non-normality in the distribution of daily temperatures is shown to be a problem in simulating extreme temperature maxima as well as of minima. It is suggested that the normal distribution used in the generation of daily temperatures in the widely used Richardson (1981) generator, and its derivations, be supplanted by a more appropriate distribution that permits skewness in either direction. 相似文献