中国均一化日平均温、最高温和最低温序列1960-2008

Inhomogeneities in the daily mean/maximum/ minimum temperature （Tm/Tmax/Tmin） series from 1960- 2008 at 549 National Standard Stations （NSSs） in China were analyzed by using the Multiple Analysis of Series for Homogenization （MASH） software package. Typical biases in the dataset were illustrated via the cases of Beijing （B J）, Wutaishan （WT）, Urumqi （UR） and Henan （HN） stations. The homogenized dataset shows a mean warming trend of 0.261/0.193/0.344℃/decade for the annual series of Tm/Tmax/Tmin, slightly smaller than that of the original dataset by 0.006/0.009/0.007℃/decade. However, considerable differences between the adjusted and original datasets were found at the local scale. The adjusted Tmin series shows a significant warming trend almost everywhere for all seasons, while there are a number of stations with an insignificant trend in the original dataset. The adjusted Tm data exhibit significant warming trends annually as well as for the autumn and winter seasons in northern China, and cooling trends only for the summer in the middle reaches of the Yangtze River and parts of central China and for the spring in southwestern China, while the original data show cooling trends at several stations for the annual and seasonal scales in the Qinghai, Shanxi, Hebei, and Xinjiang provinces. The adjusted Tmax data exhibit cooling trends for summers at a number of stations in the mid-lower reaches of the Yangtze and Yellow Rivers and for springs and winters at a few stations in southwestern China, while the original data show cooling trends at three/four stations for the annual/autumn periods in the Qinghai and Yunnan provinces. In general, the number of stations with a cooling trend was much smaller in the adjusted Tm and Tmax dataset than in the original dataset. The cooling trend for summers is mainly due to cooling in August. The results of homogenization using MASH appear to be robust; in particular, different groups of stations with consideration of elevation led to minor effects i     

利用多模式对中国气温序列中不连续点的检测

发展了一种对元数据依赖程度较小的气候序列均一化思路,在缺乏元数据的基础上,采取3种不同的方法,对中国东南部地区年平均最高、最低气温序列进行了均一性检验;并对其中不连续的气温序列进行了订正.对比表明,订正后序列较订正前更为合理.在检验过程中发现,对于最低气温检验可以明显得出比最高气温更多的不连续点.为了进一步认识这个问题,对此进行了进一步分析,认为最低温度对变化更为敏感主要是由于其物理特征:最低温度一般出现在夜间,夜间大气较为稳定,因此一些变化(如仪器,迁站)可能引起明显的不连续现象,而最高气温往往出现在白天,因此大气混合比较充分,空间的均一性要明显强于最低温度.另外,热岛现象、台站密度等因素均是影响气温序列均一化的因素.     

Application of Multiple Analysis of Series for Homogenization to Beijing Daily Temperature Series （1960-2006）

Homogenization of climate observations remains a challenge to climate change researchers, especially in cases where metadata (e.g., probable dates of break points) are not always available. To examine the influence of metadata on homogenizing climate data, the authors applied the recently developed Multiple Analysis of Series for Homogenization (MASH) method to the Beijing (BJ) daily temperature series for 1960--2006 in three cases with different references: (1) 13M---considering metadata at BJ and 12 nearby stations; (2) 13NOM---considering the same 13 stations without metadata; and (3) 21NOM---considering 20 further stations and BJ without metadata. The estimated mean annual, seasonal, and monthly inhomogeneities are similar between the 13M and 13NOM cases, while those in the 21NOM case are slightly different. The detected biases in the BJ series corresponding to the documented relocation dates are as low as -0.71^oC, -0.79^oC, and -0.5^oC for the annual mean in the 3 cases, respectively. Other biases, including those undocumented in metadata, are minor. The results suggest that any major inhomogeneity could be detected via MASH, albeit with minor differences in estimating inhomogeneities based on the different references. The adjusted annual series showed a warming trend of 0.337, 0.316, and 0.365^oC (10 yr)^-1 for the three cases, respectively, smaller than the estimate of 0.453^oC (10 yr)^-1 in the original series, mainly due to the relocation-induced biases. The impact of the MASH-type homogenization on estimates of climate extremes in the daily temperature series is also discussed.     

Further-Adjusted Long-Term Temperature Series in China Based on MASH

A set of homogenized monthly mean surface air temperature(SAT) series at 32 stations in China back to the 19 th century had previously been developed based on the RHtest method by Cao et al.,but some inhomogeneities remained in the dataset.The present study produces a further-adjusted and updated dataset based on the Multiple Analysis of Series for Homogenization(MASH) method.The MASH procedure detects 33 monthly temperature records as erroneous outliers and152 meaningful break points in the monthly SAT series since 1924 at 28 stations.The inhomogeneous parts are then adjusted relative to the latest homogeneous part of the series.The new data show significant warming trends during 1924–2016 at all the stations,ranging from 0.48 to 3.57?C(100 yr)~(-1),with a regional mean trend of 1.65?C(100 yr)~(-1);whereas,the previous results ranged from a slight cooling at two stations to considerable warming,up to 4.5?C(100 yr)~(-1).It is suggested that the further-adjusted data are a better representation of the large-scale pattern of climate change in the region for the past century.     

Impacts of Reference Time Series on the Homogenization of Radiosonde Temperature

Using radiosonde temperatures of 92 selected stations in China,the uncertainties in homogenization processes caused by different reference series,including nighttime temperature,the NCEP (National Centers for Environmental Prediction) and ERA-40 (European Centre for Medium-Range Weather Forecasts) forecasting background,are examined via a two-phase regression approach.Although the results showed limited consistency in the temporal and spatial distribution of identified break points (BPs) in the context of metadata events of instrument model change and correction method,significant uncertainties still existed in BP identification,adjustment,and impact on the estimated trend.Reanalysis reference series generally led to more BP identification in homogenization.However,those differences were parts of global climatic shifts,which may have confused the BP calculations.Discontinuities also existed in the reanalysis series due to changes in the satellite input.The adjustment values deduced from the reanalysis series ranged widely and were larger than those from the nighttime series and,therefore,impacted the estimated temperature trend.     

中国近百年温度曲线的对比分析

 温度变化是全球变化研究中非常重要的基础性问题,在中国近百年温度变化方面,十几年来已取得了明显进展,这首先表现在建立了若干条全国平均气温序列,而几条主要序列间的相关系数在0.73～0.97之间。同时,这些进展也表现在基础资料质量提高、空间覆盖面扩大、序列均一性改善以及结果可靠性提高等方面。对多序列进行综合分析得到的新结果显示,1906-2005年中国的年平均气温上升了（0.78±0.27）℃,2007年是我国近百年来最暖的一年;代表性分析显示,现有的几条中国温度序列中除覆盖完整的序列外,其他序列在1920或1930年代以前可能主要反映中国东部变化情况,但在此之后则能较好地代表全国大部分地区的气候变化特征。     

近50年我国探空温度序列均一化及变化趋势

利用1958—2005年我国116个站探空温度序列研究了我国高空温度变化趋势。首先通过静力学质量控制和两相回归法对原始序列进行了均一化处理。我国探空温度序列存在明显的间断点, 间断点的订正对于序列的趋势影响较为显著。缺测率是影响我国探空温度序列应用性的重要因子, 也是区域平均趋势统计中台站取舍的指标, 减少台站总数会削弱我国对流层升温和平流层降温的变化趋势。分析表明: 70%作为最小资料有效率标准最为合理。为满足最小资料有效率, 选取92个站统计我国高空温度变化趋势的区域平均值。结果表明: 1958-2005年, 平流层下层和对流层上层降温, 对流层中、低层升温; 高空温度变化趋势与研究时段明显相关, 1958-1978年我国高空大气整层均为降温; 1979—2005年, 对流层中低层升温最为明显, 增暖的幅度随高度增加而减小, 400 hPa以上各层转为降温。对流层的升温始于20世纪80年代, 升温幅度与全球尺度的平均值有所不同。     

An Analysis of the Discontinuity in Chinese Radiosonde Temperature Data Using Satellite Observation as a Reference

Reconciling upper-air temperature trends derived from radiosonde and satellite observations is a necessary step to confidently determine the global warming rate. This study examines the raw and homogenized radiosonde observations over China and compares them with layer-mean atmospheric temperatures derived from satellite microwave observations for the lower-troposphere(TLT), mid-troposphere(TMT), upper-troposphere(TUT), and lower-stratosphere(TLS) by three research groups. Comparisons are for averages over China, excluding the Tibetan Plateau, and at individual stations where metadata contain information on radiosonde instrument changes. It is found that major differences between the satellite and radiosonde observations are related to artificial systematic changes. The radiosonde system updates in the early 2000 s over China caused significant discontinuities and led the radiosonde temperature trends to exhibit less warming in the middle and upper troposphere and more cooling in the lower stratosphere than satellite temperatures. Homogenized radiosonde data have been further adjusted by using the shift-point adjustment approaches to match with satellite products for China averages. The obtained trends during 1979–2015 from the re-adjusted radiosonde observation are respectively 0.203 ± 0.066, 0.128 ± 0.044, 0.034 ± 0.039, and –0.329 ± 0.135 K decade^–1 for TLT, TMT, TUT, and TLS equivalents. Compared to satellite trends, the re-adjusted radiosonde trends are within 0.01 K decade^–1 for TMT and TUT, 0.054 K decade^–1 warmer for TLT, and 0.051 K decade^–1 cooler for TLS. The results suggest that the use of satellite data as a reference is helpful in identifying and removing inhomogeneities of radiosonde temperatures over China and reconciling their trends to satellite microwave observations. Future efforts are to homogenize radiosonde temperatures at individual stations over China by using similar approaches.     

Detection and Adjustment of Undocumented Discontinuities in Chinese Temperature Series Using a Composite Approach

Annually averaged daily maximum and minimum surface temperatures from southeastern China were evaluated for artificial discontinuities using three different tests for undocumented changepoints. Changepoints in the time series were identified by comparing each target series to a reference calculated from values observed at a number of nearby stations. Under the assumption that no trend was present in the sequence of target-reference temperature differences, a changepoint was assigned to the target series when at least two of the three tests rejected the null hypothesis of no changepoint at approximately the same position in the difference series. Each target series then was adjusted using a procedure that accounts for discontinuities in average temperature values from nearby stations that otherwise could bias estimates of the magnitude of the target series step change. A spatial comparison of linear temperature trends in the adjusted annual temperature series suggests that major relative discontinuities were removed in the homogenization process. A greater number of relative change points were detected in annual average minimum than in average maximum temperature series. Some evidence is presented which suggests that minimum surface temperature fields may be more sensitive to changes in measurement practice than maximum temperature fields. In addition, given previous evidence of urban heat island (i.e., local) trends in this region, the assumption of no slope in a target-reference difference series is likely to be violated more frequently in minimum than in maximum temperature series. Consequently, there may be greater potential to confound trend and step changes in minimum temperature series.     

呼伦贝尔市2012年1月下旬低温天气统计分析

文章利用呼伦贝尔市16个国家气象观测站的温度资料,并选择上海、北京与海拉尔3个代表站温度资料进行统计分析,重点对呼伦贝尔市2012年1月下旬出现的持续低温天气进行统计分析。结果表明:近50a气温整体趋势是在上升的,但海拉尔气温上升的幅度比较小。在气候变暖的背景下,气候变的比较异常,极端事件也在增多,甚至出现持续性极端低温天气。     

北京1960—2008年气候变暖及极端气温指数变化特征

应用均一化逐日气象观测资料,分析了北京地区1960—2008年气候变暖及主要极端气温指数的统计特征。结果表明：近49年来北京年平均气温增温速率约为0.39℃/10a,最高、最低气温变化具有明显的非对称性。霜冻日数和气温年较差呈现下降趋势,暖夜指数及热浪指数呈现上升趋势,除气温年较差外,其他极端气温指数的气候变率均在加大。北京年平均气温及极端气温指数主要存在21年、15～17年及准10年周期特征。年平均气温与极端气温指数之间存在较强相关性,气候变暖突变发生前后某些极端气温指数发生频率表现出明显差异。自1980年起,北京市区极端最高气温及其增温率明显高于近郊和远郊,高温日数市区多于近郊,近郊多于远郊;近、远郊极端最低气温温差高于城、近郊温差。     

基于均一化格点资料的全球变暖趋缓期中国气温变化特征分析

利用1961-2014年水平分辨率为0.5°×0.5°的均一化气温网格数据,分析全球变暖趋缓期（1998-2014年）中国气温的变化特征。结果显示：1998-2014年中国气温上升趋缓明显,与增暖期（1985-1997年）相比,年平均气温和年平均最高气温由升温趋势转为降温趋势,分别为-0.05℃/10a和-0.11℃/10a,而年平均最低气温仍保持弱的上升趋势（0.06℃/10a）。全球变暖趋缓期中国的增暖型发生了显著变化：北方地区由增温趋势转为降温趋势,青藏高原和西南地区则呈现出相对强的增温趋势;从季节来看,冬季降温最强、夏季增温较其他季节偏强,而冬季（强降温）正是中国增暖趋缓的主要贡献季节。增温最强的要素仍然是最低气温。     

河北保定气象站长序列气温资料缺测记录插补和非均一性订正

基于多源的气温月值资料,在数据整合和初步质量控制基础上,同时采用标准化序列法和多元线性回归法对河北保定气象站1913-2014 年月平均气温、最高气温和最低气温资料进行了插补。通过交叉检验法分析发现,标准化序列法插补得到的气温序列效果较好,并且气候统计特征与同区域周边站的研究结果更具一致性。利用惩罚最大F 检验（PMF）对插补后序列的均一性进行了检验,结果表明：通过插补得到的保定站百年气温月值序列的均一性相对较好,仅月平均最低气温序列存在2 个显著间断点,分别由同类型仪器的更换和台站迁移导致,研究中采用分位数匹配（QM）对其进行了订正,建立了保定站百年气温月值序列。通过与邻近单站及我国中东部区域均一化百年气温序列的综合对比显示,本文建立的保定站百年气温月值序列与邻近单站的相关性基本达到0.8 以上;从增暖趋势来看,保定站与中东部区域平均序列分别达0.121 ℃/10a、0.204 ℃/10a,基本在同一量级内：这一定程度上说明建立的保定站百年气温序列相对合理。     

Trends of Temperature Extremes in Summer and Winter during 1971–2013 in China

The diurnal temperature range(DTR) has decreased dramatically in recent decades, but it is not yet obvious whether the extreme values of DTR have also reduced. Based on the daily maximum and minimum temperature data of 653 stations in China, a set of monthly indices of warm extremes, cold extremes, and DTR extremes in summer(June, July, August) and winter(December, January, February) were studied for spatial and temporal features during the period 1971–2013. Results show that the incidence of warm extremes has been increasing in most parts of China, while the opposite trend was found in the cold extremes for summer and winter months. Both increasing and decreasing trends of monthly DTR extremes were identified in China for both seasons. For high DTR extremes, decreasing trends were identified in northern China for both seasons, but increasing trends were found only in southern China in summer, while in winter, they were found in central China. Monthly low DTR extreme indices demonstrated consistent positive trends in summer and winter, while significant increases(P 0.05) were identified for only a few stations.     

Performance of Regional Integrated Environment Modeling System (RIEMS) in the Simulation of Surface Air Temperature over East Asia

Regional climate models (RCMs) have the potential for more detailed surface characteristic and mesoscale modeling results than general circulation models (GCMs).These advantages have drawn significant focus on RCM development in East Asia.The Regional Integrated Environment Modeling System,version 2.0 (RIEMS2.0),has been developed from an earlier RCM,RIEMS1.0,by the Key Laboratory of Regional ClimateEnvironment for Temperate East Asia (RCE-TEA) and Nanjing University.A numerical experiment covering 1979 to 2008 (simulation duration from 1 January 1978 to 31 December 2008) with a 50-km spatial resolution was performed to test the ability of RIEMS2.0 to simulate long-term climate and climate changes in East Asia and to provide a basis for further development and applications.The simulated surface air temperature (SAT) was compared with observed meteorological data.The results show that RIEMS2.0 simulation reproduced the SAT spatial distribution in East Asia but that it was underestimated.The simulated 30-year averaged SAT was approximately 2.0°C lower than the observed SAT.The annual and interannual variations in the averaged SAT and their anomalies were both well reproduced in the model.A further analysis of three sub-regions representing different longitudinal ranges showed that there is a good correlation and consistency between the simulated results and the observed data.The annual variations,interannual variations for the averaged SAT,and the anomalies in the three sub-regions were also captured well by the model.In summary,RIEMS2.0 shows stability and does well both in simulating the long-term SAT in East Asia and in expressing sub-regional characteristics.     

冬季中国东部与北极之间近地面温度变化的年际联系

利用NCEP/NCAR再分析资料和国家气象信息中心整编的425站气温资料,借助经验正交函数分解（EOF）、相关分析和回归分析等方法探讨1956~2015年冬季北极及中高纬度近地面温度、西伯利亚高压的变化特征以及两者与中国东部气温直接和间接的年际联系。为此定义了3个西伯利亚高压指数,即西伯利亚高压中心强度指数（SHCI）、西伯利亚高压面积指数（SHA）和西伯利亚高压东边界指数（SHEB）。结果表明:从1998年开始冬季巴伦支海、喀拉海迅速增温,并在年际尺度上与中国东部气温存在显著的负相关关系,即北极近地面温度与中国东部气温的直接联系。同时,西伯利亚高压的3个指数也与北极地区近地面温度和中国东部气温有较好的年际关系,体现了西伯利亚高压是联系北极和东亚气候的桥梁,当北极近地面温度升高（降低）时,西伯利亚高压中心强度增强（减弱）,面积扩大（缩小）,东边界东伸（西退）,中国东部气温降低（升高）,即北极近地面温度（西伯利亚高压）与中国东部气温的间接（直接）联系。最后,讨论了北极近地面温度变化影响中国东部气温的可能物理机制。     

非对称性增温对农业生态系统影响研究进展

该文概述了北半球和我国气候变暖中增温的非对称性特征:北半球气候变暖存在明显的季节差异和昼夜不同步性, 大部分地区冬、春季升温高于夏、秋季, 日最低气温升幅是日最高气温升幅的2~3倍; 近50年我国近地表气温升高主要是最低气温明显上升的结果, 日最低气温升幅是日最气高温升幅的2~3倍, 与北半球基本一致; 升温最显著的季节为冬季和春季。在此基础上概述了非对称性增温对农业生态系统的影响, 论述了非对称性增温对农作物物候和农作物产量的影响, 得出最低气温升高促使整个生长季延长, 促使早春作物物候期提前, 但最低气温和最高气温对不同作物的物候以及同一作物的不同发育阶段影响不同。现有研究多采用模型或统计的方法研究气候变暖对作物生长的影响, 认为温度升高对作物有“强迫成熟”效应; 而现有的最低气温升高和最高气温升高对作物生长影响的研究结果并不一致。非对称性增温对农作物影响的实验研究极少, 且缺乏对模型模拟结果的实验验证。     

全球气候变暖背景下兰州地面平均气温的变化

利用兰州1932-2002年逐月地面月平均温度资料，分析了兰州71年来温度的基本气候特征、年代际变化、突变、异常冷暖和变化趋势等。分析表明：71年来年和四季气温大体都经历了两个暖期和一个冷期．第一暖期的增暖主要在春、夏、秋季。冬季则处在冷期中；第二暖期首先从冬季开始，四季间相隔1～2年后陆续大幅度增暖．第二暖期增暖幅度明显高于第一暖期，持续时间也长于第一暖期。最大的特点是四季同时增暖，冬季增暖幅度最大。1960年代是最冷的10年，以夏季降温最为明显；1990年代是最暖的10年，以冬季增暖最为明显。1990年代发生异常的频次最高，其次是1960年代和1970年代，最少的是1980年代。71年来．兰州年平均气温以1．4℃／100a线性趋势上升，高于北半球和全国水平，近10年冬秋季增温率最大。     

近50年中国气温日较差的变化趋势分析

利用近50年的气温观测资料,对中国地区的气温日较差的空间分布和时间序列变化特征进行了分析。同时分析了与日最高气温、最低气温以及平均气温时空分布之间的关系。结果发现,近50年来气温日较差呈下降趋势,其平均减小幅度为高纬度地区大于低纬度地区;不同地区及同一地区的DTR季节变化特征也不相同,我国北方多为冬季DTR下降最大,其次是春季和秋季,夏季最小。在黄淮和长江流域,以夏季和春季DTR下降最为显著。华南地区仍以冬季下降最大。气温日较差整体呈现下降趋势,中高纬度下降比低纬度明显。在相同纬度带上,由于地理状况的不同,变化趋势有所不同。同时,气温日较差的变化有明显的区域和季节性差异,特别在西部的青藏高原和新疆地区的DTR变化与东部地区的差异明显。     

Correlation between Atmospheric Water Vapor and Diurnal Temperature Range over China

Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.