地面气候资料序列均一性检验与订正系统

采用国内外常用的几种气候序列均一性检验与订正方法,研制了气候序列均一性检验与订正系统,用于检验地面测站由于迁站、仪器变更、环境恶化等因素造成气候序列的非均一性,并进行订正.使用该系统对浙江省地面36个测站的年平均温度、年平均风速及年降水量序列进行了均一性检验,效果较好.     

地面气候资料均一性研究进展

气象台站观测的地面气候资料是气候变化研究的重要基础,气候资料的均一性检验和订正对于提高气候资料的质量和均一性状况具有实用意义和价值.通过回顾近年来国内外地面气候资料均一性研究进展、研究技术及发展趋势,总结了目前国内广泛应用的两种较为成熟的均一化方法(RHtest和MASH)及其对气温、风速资料均一性研究取得的一些成果,...     

定点观测气候序列的均一性研究

文章分析了气候资料产生非均一性的原因，介绍了近年来国内、外气候资料均一性研究的方法以及一些国家利用这些研究方法对本国或区域气候序列均一性问题的研究成果。对我国气象观测站观测站址、仪器变化等因素进行了总结，并介绍了我国气象资料均一性检验的一些结论，讨论了与气象资料均一性研究相关的一些问题。     

中国地面月气候资料质量控制方法的研究

由于气象台站信息变化以及观测规范的频繁变动, 使中国地面气象资料序列比较复杂。该文在分析中国地面历史气象资料中可能存在的非均一性和错误性、研究月气候资料序列存在的可能分布状态的基础上, 提出了中国地面月气候资料质量控制技术。通过分析认为, 中国地面月气候资料的质量控制, 应把下列3种方式结合起来, 进行综合质量检测:①把12个月的气候资料序列联合起来, 进行长时间连续性错误资料检测; ②把时间序列变换为接近正态分布的均一序列后, 进行时间域和空间域的奇异值检测; ③对检测出的连续性可疑资料和单个数据点的奇异值进行人工分析辨别。利用上述质量控制方法, 对1971—2000年中国地面700多基准基本站月统计气候资料进行了质量检查, 最后介绍了质量检查结果。     

气候变化研究使用气候资料受影响的可能性分析

通过对气候变化研究所要用到站点的地面气候资料在观测站点确定及在收集过程中可能受到的各种影响进行全面分析得出：进行气候变化的研究时,首先应评估站点的代表性范围以决定气候资料是否可用;其次应详尽了解站点的历史沿革资料,以便掌握气候资料在收集过程中其代表性是否发生变化;最后考察观测时期内气候资料是否具有均一性,以便考虑是否要对其作序列订正。     

大陈迁站前后气象资料序列的均一性检验

大陈气象站于1982年10月进行了站址迁移,站址的变动,涉及到迁站前后两段观测资料是否有均一性问题。所谓资料序列的均一性,一般把只受气候变化影响的气象资料序列称为均一性序列,或称作连续性序列。若气象要素随时间的变化不仅受气候条件的影响,而且又受诸如站址的迁移、周围生态环境的改变、观测规范和仪器的更换等等人为的影响,这样的资料序列认为是非均一性序列,或称之为非连续性序列。     

资料均一化对气温变化趋势及其城市化偏差估计的影响：以北京地区为例

当前的地面气候观测资料普遍存在非气候性因素导致的非均一性,对气候变化监测和研究结论可靠性造成重要影响。结合观测台站的历史沿革数据,使用ACMANT和Pairwise Comparisons方法以及RHtest V4软件,对北京地区20个台站均一化前的月平均气温序列进行了非均一性检验和订正,最后评估了均一化对北京地区气温序列变化趋势及其城市化偏差估算的影响。结果表明：除元数据中记录的断点外,无元数据记录的断点也会对序列的趋势变化造成明显影响,其中乡村站最显著;经过订正,1958—2018年整个北京地区、乡村站以及城市站增温趋势分别为0.27℃/(10 a)、0.10℃/(10 a)和0.32℃/(10 a),较订正前分别上升了0.03℃/(10 a)、0.06℃/(10 a)和0.02℃/(10 a)。利用均一化资料估算,1958—2018年北京观象台的城市化影响为0.24℃/(10 a),城市化贡献率为70.2%,评估结果较前人结论有所降低。可见,在现有的北京地区气温资料序列中,仍可能存在较明显的非均一性和未被记录的断点,对区域平均气温趋势估算具有显著影响。     

江西省地面气象台站沿革及其对观测资料序列均一性的影响

介绍了江西省地面气象台站沿革情况,通过资料对比,分析了观测仪器、仪器安装高度和观测方法等的变化对观测资料序列均一性的影响。结果表明,气象台站历史沿革,特别是台站迁移以及观测仪器类型、仪器安装高度、观测时制的改变,直接影响观测记录的连续性和气候资料序列的均一性。研究认为,气象台站历史沿革信息,在检验、订正、分析气候资料序列时不可忽略。在使用历史资料时,应分析和判断台站沿革对气候资料序列均一性的影响。     

五台山站历史气候资料的均一性分析

以山西五台山地面观测站为例,对建站(1957年1月)至2005年的年、季节平均气温、最高和最低气温、相对湿度和降水观测资料序列作均一性分析,结合历史沿革变化(包括迁站、仪器变化和观测业务改变等),得出这些因素对不同气候要素均一性的影响情况.从与该站不同要素序列相关性较好、水平距离最近的台站中选取若干站点作为待检台站的参考台站建立了各自的参考序列作为均一性检查的对比序列,采用国际上应用较为广泛的标准正态检验(SNHT)方法分别对各种要素进行了统计学检验.对统计方法得到的不连续点(不均一性产生年份)进行了总结分析,发现台站迁移对于温度、相对湿度观测序列的均一性带来的影响非常明显,其中对最高气温序列影响最为显著,达到5.5℃.深入分析还表明,迁址对各要素的影响程度各有区别:对相对湿度的年均和春季序列也产生了较为明显的非均一性,而对降水量的影响则并不显著.综合分析表明,常用观测要素的均一性检验和订正是局地气候变化检测的基础环节,但不同要素的均一性受到各种因素影响的表现程度各不相同,需要加以区别和深入研究.     

我国气候资料均一性研究现状与展望

时空均一的气候资料是气象科研、业务和服务的基础。介绍了气候资料均一性的基本概念、涉及范围、主要原因以及解决非均一性问题的意义。在此基础上,阐述了国际上气候资料均一性研究的动态和技术发展历程,指出以高时空分辨率的均一化为标志的第二代气象数据产品研发趋势为气候资料均一性研究带来良好的发展机遇和严峻的挑战;结合对我国地面、高空和辐射三类气候资料均一性概况和相关研究现状的总结,分析了我国在相关领域研究的深度和广度上存在的差距和不足,以及当前需要解决的关键科学和技术问题。最后,就如何正确认识气候资料的均一性,如何深化我国气候资料均一性研究,加强气候数据产品研发,实现我国数据产品研发技术和管理水平上一个新台阶等提出了建议。     

南海海洋观测台站海表温度资料的均一性检验与订正

采用最大惩罚T检验（Penalized Maximum T Test,PMT）方法,结合海洋台站元数据信息,选取临近气象站做为参考站,对中国南海9个海洋观测台站月平均SST资料序列进行均一性检验,在充分考虑区域性气候变化因素的影响下,对检验结果进行气候合理性分析并对不连续点进行订正。结果表明:（1）通过多种数据的相关性比较和分析发现,临近气象站的气温资料序列是南海台站SST资料订正最优的参考序列;（2）平均每个海洋台站SST资料序列存在1~2个不连续点,其中站址变迁、仪器变更和环境变化对均一性的影响较大;（3）订正后的南海SST序列质量有大幅提高,表明南海SST具有更明显的增暖趋势。      

中国地面相对湿度非均一性检验及订正

利用加拿大环境部气候研究中心研发的PMTred和PMFT方法,选取均一的邻近站为参考站,使用相关系数权重平均构建参考序列,结合元数据信息,对1951-2014年中国2400多个国家级地面站月平均相对湿度进行了非均一性检验与订正,并分析了造成相对湿度序列非均一的主要原因。结果表明,中国地面相对湿度资料存在较严重的非均一问题,68%的台站存在断点,人工观测转自动观测、迁站和时次变化是造成序列非均一的主要原因。整套资料负订正量所占比例较高,订正范围主要集中在-5%～0之间,这种负订正量与人工转自动观测后相对湿度观测值偏低有密切关系。这也使得订正后中国平均相对湿度趋势与订正前存在明显差异,订正前中国平均相对湿度呈下降趋势,订正后相对湿度没有趋势性变化。     

地面气象站环境变化对气温序列均一性影响

为研究浙江省地面气象站环境变化对气温序列均一性的影响程度,采用测站历史沿革资料,对全省测站环境的时空演变进行了分析。采用距平累加、偏差界限值、F值检验法,对36个代表站的年平均气温序列进行均一性检验,并对非均一性产生的原因进行分析。结果表明:1971~2004年,浙江省测站的地理环境有显著改变;36站中有39%的测站为非均一性,产生非均一性的测站中,迁站原因占57%,环境恶化占36%;测站迁站引起的非均一性多发生在1980年以后;测站迁站时,新旧站址海拔高度差大且地理环境差异显著是造成气温序列非均一性的主要原因,迁站后气温序列较旧址存在偏高或偏低现象,其值对累年平均值有影响。指出了测站在迁移或环境变化过程中应注意的事项,以助于减少气温序列非均一性。     

多种方法在年平均风速均一性检验中的效果对比

针对安徽省天长和宿松气象站建站至2010年逐年平均风速资料,分别利用直接检验方法和3种间接检验方法：标准正态均一检验（the standard normalhomogeneity test,SNHT）、惩罚最大t检验（the penalized maximal t test,PMTT）和惩罚最大F检验（the penalized maximal Ftest,PMFT）,对这两个气象站逐年平均风速序列进行了均一性检验,并对不同检验方法的效果进行了对比分析。研究结果表明：1）站址迁移、观测场环境变化、仪器变更以及测风手段变化等均能对年平均风速序列的均一性产生影响,其中测风手段变化的影响最为明显。2）由于以气象台站观测记录为依据,直接检验得到的结果最为真实可信;此外SNHT、PMTT和PMFF方法对年平均风速序列的间断点均有一定的检验能力,但遗漏间断点的情况也比较明显。因而在年平均风速序列的均一性检验中,若气象台站观测记录相对较齐全,首先考虑采用直接检验,然后再考虑补充采用其他间接检验手段。     

塔城地区气象（候）站温度的均一性检验

采用SNHT方法．结合台站历史沿革信息,对塔城地区气象（候）站1960--2006年的年平均温度、年平均最低温度序列进行均一性检验。结果表明,年平均温度资料质量基本可靠,站址迁移是引起年最低温度非均一性的主要原因：     

Detecting and adjusting temporal inhomogeneity in Chinese mean surface air temperature data

Adopting the Easterling-Peterson (EP) techniques and considering the reality of Chinese meteorolog-ical observations, this paper designed several tests and tested for inhomogeneities in all Chinese historicalsurface air temperature series from 1951 to 2001. The result shows that the time series have been widelyimpacted by inhomogeneities resulting from the relocation of stations and changes in local environmentsuch as urbanization or some other factors. Among these factors, station relocations caused the largestmagnitude of abrupt changes in the time series, and other factors also resulted in inhomogeneities to someextent. According to the amplitude of change of the difference series and the monthly distribution featuresof surface air temperatures, discontinuities identified by applying both the E-P technique and supportedby China‘s station history records, or by comparison with other approaches, have been adjusted. Basedon the above processing, the most significant temporal inhomogeneities were eliminated, and China‘s mosthomogeneous surface air temperature series has thus been created. Results show that the inhomogeneitytesting captured well the most important change of the stations, and the adjusted dataset is more reli-able than ever. This suggests that the adjusted temperature dataset has great value of decreasing theuncertaities in the study of‘ observed climate change in China.     

Homogenization of Surface Pressure Data in Tianjin,China

Based on a hydrostatic check, a preliminary quality control procedure was applied to the hourly surface air pressure(SAP) and sea level pressure(SLP) data from 13 surface observation stations in Tianjin, China. The daily and monthly series of the two pressures were tested for homogeneity with the RHtestsV5 software package and corrected by using the surface air temperature data as a reference. The results showed that 5 and 3 of the 13 stations had significant breakpoints in their SAP and SLP data, respectively, mainly caused by station relocation. Quantile matching adjustments showed that both pressures were dominated by positive deviation corrections and adjustments, with probability densities 0.2 concentrated in the ranges 0.02 to 1.80 and-0.02 to 1.64 hPa. Comparison of the variances and trends of the two pressures before and after adjustment showed that homogeneity correction can greatly reduce the influence of abnormal discrete pressure data and make the long-term trends of the series more reasonable.Taking Baodi station(54525), which has the most significant correction results, as an example, the trend amplitude of the adjusted SAP and SLP was increased by 0.316 and 0.294 hPa(10 yr)-1(95% confidence level), respectively,clearly weakening the sudden reduction induced in the two pressure series by the relocation of this station. Comparison with similar products showed that the adjusted data were better than those from the China Meteorological Administration. Therefore, the reliability of the surface pressure data and the processing techniques have been improved.     

Homogeneity assessment of a station climate series (1933–2005) in the Metropolitan Area of S?o Paulo: instruments change and urbanization effects

This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale, regarding daily precipitation, relative humidity, maximum (TMax), minimum (TMin), and wet bulb temperatures. Among these quantities, only precipitation does not exhibit any inhomogeneity. A clear signal of change of instruments in 1958 was detected in the TMax and relative humidity data, the latter certainly because of its strong dependence on temperature. This signal is not very clear in TMin, but it presents non-climatic discontinuities around 1953 and around 1970. A significant homogeneity break is found around 1990 for TMax and wet bulb temperature. The discontinuities detected after 1958 may have been caused by urbanization, as the observed warming trend in the station is considerably greater than that corresponding to regional climate.     

RESEARCH OF THE INHOMOGENEITY TEST OF CLIMATOLOGICAL DATA SERIES IN CHINA*

Some achievements on the inhomogeneity test of climatological data series and some correlative conclusions were described,from which we concluded that it was very necessary to test the homogeneity of the Chinese climatological data series.Many techniques on this field developed by foreign experts are suitable for Chinese climatological series,and the main factors for the inhomogeneity of the Chinese climatological data are the relocation of stations and the change of instruments.