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.     

1979—2012年中国探空相对湿度资料的非均一性检验与订正

利用加拿大环境部气候研究中心研发的PMTred非均一性检验方法,以ERA interim资料作为参考序列,应用中国区域各探空台站详细的元数据信息为主要断点判断依据,对1979—2012年我国125个探空台站各标准等压面月平均探空相对湿度资料进行了非均一性检验和订正。并结合详细的元数据信息分析了造成我国探空相对湿度序列非均一问题形成的主要原因及对资料的影响程度。结果表明：仪器换型、探测系统资料整理计算方式变化以及辐射订正方法改变和探测系统升级等是造成这一时段中国区域月平均探空相对湿度资料不均一的主要原因。其中,2002年以后的L波段雷达 电子探空仪换型造成了相对湿度资料非常明显的不连续问题,这主要是由于早期59 701型探空仪穿云挂水,造成探测到的相对湿度资料明显偏湿。两个观测时次相对湿度序列不均一的台站数和断点数随高度的增加而增加。各标准等压面上月平均相对湿度序列不均一的探空台站平均订正幅度也随着高度的升高而增大,并且订正量为负值的比例在整套订正资料中所占的比例较高,说明我国的探空月平均相对湿度原始观测资料有明显高估的问题。1979—2012年以来,从全国的情况来看,订正前全国850~300 hPa 5个标准等压面全部为相对湿度降低趋势。但是订正后,850~300 hPa这5个标准等压面在1979—2012年相对湿度的变化趋势均不显著。     

我国东部夏季降水量长年代资料的插补、订正及效果检验

使用均值生成函数、标准正态均一性检验方法和相关分析等方法对我国东部地区96个观测站1931—2020年夏季降水量长年代资料进行了一系列插补、检验、订正及效果分析等工作。结果表明：(1)均值生成函数拟合的1931—2020年各站夏季降水量资料的整体趋势和极值与观测值均有较好的一致性,其中无缺测资料的6个站点观测值和拟合值在距平符号一致率上达到了86.1%,可以满足插补工作的需要。(2)对1931—1950年和1951—2020年2个时段的夏季降水量资料,用平均值和方差2个统计量对插补后的资料进行差异性检验,共有8站具有显著性差异。(3)对插补后的1931—2020年夏季降水量资料进行了均一性检验和均一化订正,其中13站存在非均一性。(4)将订正后的站点资料与CRU＿TS4.05(University of East Anglia Climatic Research Unit Global 0.5°Monthly Time Series)数据库的格点资料进行空间分布相似度分析,2套资料在1931—1950、1951—2020和1931—2020年这3个时段的空间相关系数分别达到了0.90,...     

Mathematical modelling of the annual temperature wave based on monthly mean temperatures,and comparisons between local climate trends at seven Norwegian stations

Summary Based on observed monthly mean temperatures, it is possible to construct a simple mathematical model of the annual variation of daily mean temperature, the annual temperature wave. For periods of 15 years, the model gives a good correlation with the observed monthly values. The model may be used as a tool for the generation of daily mean temperatures for the corresponding period. It is continuous, differentiable and strictly monotonous between the unique maximum and the minimum of the curve. Consequently, climate quantities of interest for each period can be calculated by the means of simple mathematical analyses. The model was tested by reproducing values for quantities such as annual mean temperature, winter mean temperature, summer mean temperature and temperature sums. Model calculated values, fit values calculated directly from observed data well. The model was also tested by comparing results from two different but neighbouring stations. There was a good correlation between the results from the two stations. Long homogenised time series with 130 years of monthly mean temperature from seven Norwegian stations were analysed by means of the model. It was found that the Frost Free Season Length and the Growth Season Length had increased for all stations by 10–20 days/100 years in the period 1871–1990. The Summer Half-year Length, even if it was defined relative to the annual mean temperature, also increased for all stations by 4–9 days/100 years. The Hot Season Length showed positive trends as well, and for the five stations in Southern Norway, the trends were as high as 18–29 days/100 years. The Heat Sum had increased by 6–11% for southern stations and 20–22% for the northern stations. The results indicate that the level as well as the shape of the annual temperature wave changed in the period from 1871 to 1990. Some of the results for the period 1990–1999 diverge substantially from the trends, possibly indicating significant changes in the shape of the annual temperature wave in this last period.     

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.     

Seasonal climatic variability

Abstract

An analysis of variance of the 1000–500 mb thickness field is performed to investigate the possibility of seasonal change in climatic variability during the period 1949 to 1975.

The mean thickness and measures of transient eddy, standing eddy and north‐south variance, averaged over the region from 25°N to the Pole, are analysed for the annual average and for each of the four seasons. For the annually averaged data, the only statistically significant trend is a linear decrease in mean thickness. None of the variability measures display significant trends in annually averaged values.

On a seasonal basis, a significant trend in mean thickness is found in three of the four seasons. Several seasonal measures of variability show statistically significant trends. The most notable result of the analysis is an apparent increasing trend in summer season values of both transient and standing eddy measures of variability.

The results of this study reiterate those of a previous study that found no overall change in climatic variability during the period. In addition, however, the data suggest an increase in variability during the summer season although this increase is not sufficient to affect the overall annually averaged value.     

The Black Sea level trends from tide gages and satellite altimetry

Obtained are the estimates of the Black Sea level trends for the period of 1992–2005 as derived from the tide-gage and satellite altimetry data. An estimated rate of the mean sea level rate calculated from the averaged altimetry data is 7.6 ± 0.3 mm/year that is by 2–3 times higher than the estimates for the previous periods. Such high values of the trend are evidently associated with the sea level variability features at the 10-year temporal scale. The Black Sea level trend is characterized by the high spatial variability: it amounts to 8–9.5 mm/year in the coastal areas of the Black Sea basin that exceeds the trend in the deep-water part by 1.5–2 times (4.5–6 mm/year). Such distribution is an effect of the cyclonic Rim Current intensification. Based on the difference in the sea level trends obtained from in-situ and altimetry measurements, the velocity of the vertical crustal motion is estimated for the Ukrainian coastal stations of the Black Sea.     

Climate Warming, Wildfire Hazard, and Wildfire Occurrence in Coastal Eastern Spain

A climatic series (1941 to 1994) from a Mediterranean locality of NE Spain was used to calculate two wildfire hazard indices based on daily meteorological data. Both fire hazard indices increased over this period, as a consequence of increasing mean daily maximum temperature and decreasing minimum daily relative humidity. These trends were observed in both mean values of the indices and in the number of very high risk days. Annual data on the number of wildfires and burned area also show an increase from 1968 to 1994, and are significantly correlated with both fire hazard indices. Although other non-meteorological causes (e.g., human activities, fuel accumulation) have likely contributed to the observed increase of wildfires, an effect of climatic warming on wildfire occurrence is supported by this relationship.     

近57年我国气温格点数据集的建立和质量评估

在普通克里金插值方法的基础上, 引入高程因子并充分考虑插值的边界效应, 对1951:2007年我国气温站点资料进行空间结构分析和插值, 得到我国地面气温日、月、年平均值1°×1°格点数据集。数据集的质量评估结果表明:高程在我国区域气温空间结构分析和插值中起着重要作用, 高程资料的引入有效提高了大部分高山地区的插值效果; 相比站点资料, 所建立的格点数据集在描述我国年平均气温以及季节平均气温分布时更为合理, 突出了温度场的大尺度特征; 数据集反映出了我国年平均气温变化趋势主要的空间差异; 数据集较好地反映了我国年平均气温变化状况, 1951- 2007年气温变暖幅度约为1.6 ℃, 增温速率0.28 ℃/10 a, 比全球或半球同期平均增温速率明显偏高, 且气温增暖主要发生在最近的20余年之内。另外, 格点数据集显示, 1998—2007年是1951年以来最暖的10年, 其中2006年全国平均气温距平接近2000年之前的历史最高年份1998年, 而2007年全国平均气温距平值超过1998年, 达到1951年以来的历史最高值1.3 ℃, 为最暖的一年。     

1901-2007年澳门地面气温变化的分析

 利用澳门的气温观测资料, 分析了澳门1901-2007年地面气温变化的基本特征。结果表明：近107 a的升温率为0.066℃/10a, 明显低于全球平均升温率。季节平均气温的年代际变化有明显的季节差异,最大的增暖发生在春季和冬季,夏季的增暖最小;冬、夏季的变化分别有明显的时间尺度约为60 a和30 a的振动。年平均最高气温的升温率仅为最低气温的一半左右。最高气温的年代际变化呈缓慢的气候波动现象,20世纪80年代中期以后的升幅与历史上的增暖大致相当;最低气温近20多年来的增暖趋势可能是其长期（变暖）趋势的延续。年平均日较差整体来说是趋于减少的,但近30 a却趋于增加。     

Recent Climate Change at the Upper Danube—A temporal and spatial analysis of temperature and precipitation time series

The following study investigates temperature and precipitation trends in instrumental time series between 1960 and 2006 at 88 meteorological stations located in the Upper Danube Basin. Time series were tested for inhomogeneities with several common homogeneity tests, trend magnitudes of annual and seasonal time series were calculated by least square fitting and the significance of trend values was checked and quantified by the Mann-Kendall test. The results confirm a particularly strong recent Climate Change in the investigation area. Increasing temperature trends show remarkably high trend values up to 0.8°C/decade in the summer season. The trends are highly significant for all investigated summer, spring and annual time series. Winter and spring temperature trends show consistently positive trend values as well even though some time series show no significance at all and the calculated trend values are smaller. Autumn temperature trends are mostly non-significant with low values (up to 0.3°C/decade) and several negative trends. Most of the highest trend values can be found in lower altitudes whereas stations situated in alpine regions tend to show low trend magnitudes and often exhibit non-significant results. Precipitation time series show positive as well as negative trends in the annual and seasonal analysis. At most stations a precipitation decrease in summer and autumn and an increase in winter was observed during the last 47?years whereas the spring and mean annual precipitation exhibits no change at all. But most time series are not conclusive since they show predominantly no significance and they often exhibit only low trend values.     

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.     

APHRODITE高分辨率逐日降水资料在中国大陆地区的适用性

日本APHRODITE (Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation of Water Resources) 研究计划建立了一套高分辨率的逐日亚洲陆地降水数据集 (简称APHRO), 时间从1951年到2007年, 空间分辨率为0.25°×0.25°。本文从气候态、 不同等级降水量分布以及长期变化等方面分析, 通过与中国559个台站观测资料对比, 考察了该降水资料在中国地区的适用性。结果表明: (1) 气候态分布方面, APHRO降水量与台站资料一致, 并且可以准确表征雨带的季节性移动; 但是, 与台站资料相比, 这套资料的降水强度偏小, 而降水频率偏大。 (2) 考察不同等级降水量的分布发现, APHRO资料的暴雨年降水量相对偏少, 而小雨和中雨的年降水量偏多。 (3)APHRO资料揭示的近50年降水量的变化趋势与台站资料大致相同, 并能反映年平均降水频率 “西增东减” 的趋势; 两套资料近50年的年平均降水强度在东南沿海和西北部等区域都呈增加趋势, 但APHRO在华北、 东北和江淮区域的降水强度变化趋势与台站资料差异显著。此外, 在年代际变化方面, APHRO资料对中国东部降水夏季 “南涝北旱” 和 “江南春旱” 强度的描述与台站资料有所不同, 降水量的变化趋势偏弱。     

Effect of data homogenization on estimate of temperature trend: a case of Huairou station in Beijing Municipality

Daily minimum temperature (Tmin) and maximum temperature (Tmax) data of Huairou station in Beijing from 1960 to 2008 are examined and adjusted for inhomogeneities by applying the data of two nearby reference stations. Urban effects on the linear trends of the original and adjusted temperature series are estimated and compared. Results show that relocations of station cause obvious discontinuities in the data series, and one of the discontinuities for Tmin are highly significant when the station was moved from downtown to suburb in 1996. The daily Tmin and Tmax data are adjusted for the inhomogeneities. The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization. The adjustments for Tmin are larger than those for Tmax, especially in winter, and the seasonal differences of the adjustments are generally more obvious for Tmin than for Tmax. Urban effects on annual mean Tmin and Tmax trends are ?0.004°C/10 year and ?0.035°C/10 year respectively for the original data, but they increase to 0.388°C/10 year and 0.096°C/10 year respectively for the adjusted data. The increase is more significant for the annual mean Tmin series. Urban contributions to the overall trends of annual mean Tmin and Tmax reach 100% and 28.8% respectively for the adjusted data. Our analysis shows that data homogenization for the stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature, and this necessitates a careful evaluation and adjustment for urban biases before the data are applied in analyses of local and regional climate change.     

Impacts of climate change on August stream discharge in the Central-Rocky Mountains

In the snowmelt dominated hydrology of arid western US landscapes, late summer low streamflow is the most vulnerable period for aquatic ecosystem habitats and trout populations. This study analyzes mean August discharge at 153 streams throughout the Central Rocky Mountains of North America (CRMs) for changes in discharge from 1950–2008. The purpose of this study was to determine if: (1) Mean August stream discharge values have decreased over the last half-century; (2) Low discharge values are occurring more frequently; (3) Climatic variables are influencing August discharge trends. Here we use a strict selection process to characterize gauging stations based on amount of anthropogenic impact in order to identify heavily impacted rivers and understand the relationship between climatic variables and discharge trends. Using historic United States Geologic Survey discharge data, we analyzed data for trends of 40–59 years. Combining of these records along with aerial photos and water rights records we selected gauging stations based on the length and continuity of discharge records and categorized each based on the amount of diversion. Variables that could potentially influence discharge such as change in vegetation and Pacific Decadal Oscillation (PDO) were examined, but we found that that both did not significantly influence August discharge patterns. Our analyses indicate that non-regulated watersheds are experiencing substantial declines in stream discharge and we have found that 89% of all non-regulated stations exhibit a declining slope. Additionally our results here indicate a significant (α?≤?0.10) decline in discharge from 1951–2008 for the CRMs. Correlations results at our pristine sites show a negative relationship between air temperatures and discharge and these results coupled with increasing air temperature trends pose serious concern for aquatic ecosystems in CRMs.     

Temperature and Humidity Regime Changes on the Black Sea Coast in 1982-2014

Specific features of climate change in the Black Sea and on its northeastern coast for the period of 1982-2014 are investigated based on weather station data, ERA-Interim reanalysis, and satellite data on sea surface temperature. The main trends in air temperature and precipitation are revealed from weather station data and are compared with reanalysis data. The spatial peculiarities of variations in air temperature, integrated water vapor, moisture flux divergence, CAPE, and vertical velocity are analyzed. It is shown that air temperature variations on the coast highly correlate with sea surface temperature. In general, surface air temperature in the region has risen, especially in summer. Despite the increase in integrated water vapor and CAPE, no statistically significant increase was revealed for the mean amount of precipitation, for its intensity and maximum values. This fact might be associated with the moisture flux divergence increase in the region due to the intensification of large-scale downdrafts.     

Shift changes and monotonic trends in autocorrelated temperature series over Iran

Temperature data from 29 synoptic stations in Iran for a period of 40?years (1966–2005) were analyzed to test for the existence of monotonic trends and shift changes in the annual, seasonal, and monthly mean air temperature series using the Mann–Kendall and Mann–Whitney tests. The influences of significant lag-1 serial correlation were eliminated from data by the trend-free pre-whitening method prior to the trend analysis. The magnitude of the temperature trends was derived from the Theil–Sen’s slope estimator. It was found that annual mean air temperature increased at 25 out of the 29 stations, of which 17 stations showed significant monotonic trends. The magnitude of the annual mean air temperature trends averagely was (+)0.224°C per decade. Most of the stations with the significant positive monotonic trends had a significant upward shift change. The analysis indicated that the change point year of the significant upward shift changes was 1972 for the whole stations except the coastal ones. Moreover, the strongest monotonic increasing trends and upward shift changes were observed in summer especially in August and September. The spatial analysis of the mean air temperature trends revealed the highest numbers of significant monotonic trends in the big cities of Iran. These findings provide more insights for better understanding of regional temperature behavior in the study area.     

Trend analysis of maximum,minimum, and average temperatures in Bangladesh: 1961–2008

The present study is about the analysis of mean maximum and mean minimum temperatures carried out on annual, seasonal, and monthly timescales examining the data from 15 meteorological stations in Bangladesh for the period 1961–2008. Various spatial and statistical tools were used to display and analyze trends in temperature data. ArcGIS was used to produce the spatially distributed temperature data by using Thiessen polygon method. The nonparametric Mann–Kendall test was used to determine whether there is a positive or negative trend in data with their statistical significance. Sen’s method was also used to determine the magnitude of the trends. The results reveal positive trends in annual mean and mean maximum temperatures with 95 % significance. Trend test reveals that the significant positive trend is found in June to November in case of mean maximum temperature, but according to the mean minimum temperature, the situation is different and a significant positive trend was found from November to February. The analysis of the whole record reveals a tendency toward warmer years, with significantly warmer summer periods and slightly colder winters. These warming patterns may have important impacts on energy consumption, water supply, human health, and natural environment in Bangladesh.     

内蒙古地区云量时空分布及变化趋势分析

利用1983年7月至2001年9月ISCCP云气候资料集D2资料集内蒙古区域云资料和内蒙古地区117个地面观测站的多年月平均气温、降水资料,采用趋势分析方法分析了内蒙古地区总云量和高、中、低云量的时空分布和多年变化趋势,以及温度和降水的多年变化趋势。结果表明：内蒙古地区总云量、低云量、中云量呈白西向东逐渐增多,高云量自西南向东北逐渐减少的空间分布特征;19年来东部地区总云量呈增加趋势,中、西部地区总云量呈减少趋势,温度的升高可能是云量变化的原因之一,内蒙古东北部云量和降水量变化趋势一致。     

NCEP/NCAR再分析资料在青藏铁路沿线气候变化研究中的适用性

通过对青藏铁路沿线8个常规气象站的温度和降水观测资料与NCEP／NCAR再分析资料的对比,详细地考查了再分析资料用于青藏铁路沿线气候变化研究的可行性。统计对比分析表明：再分析资料可较好地反映地面气温及降水的年变化特征,可基本反映其年际变率和年际间的差异。然而,再分析的气温值系统性低于实际观测值,降水量则系统性偏大;再分析资料得出的近40年气温长期变化趋势误差较大,降水的长期趋势特别是年降水有一定的参考价值。总体而言,再分析的气温好于降水,青藏铁路沿线主体好于两端,再分析资料可用于青藏铁路沿线主体段年到年际尺度的短期气候变化研究。