基于贝叶斯模型的器测、古气候重建与气候模拟数据的融合试验

气象部门馆藏的西部最早的器测气象资料始于20世纪30年代,不能满足建立20世纪以来中国气候变化序列的需求,而古气候重建或气候模拟资料则可以延伸到器测时代以前。为了探讨长序列多源气候资料序列融合方法,采用贝叶斯方法对中国北疆地区8条树轮气温重建资料、器测资料与国际耦合模式比较计划第5阶段（CMIP5）模式模拟资料进行了融合试验。首先利用器测资料对气温代用资料进行校验与网格重建,并以此作为贝叶斯模型的先验分布,然后,用泰勒图选出了该区域气候模拟效果最佳的几个模式;最后将网格重建和气候模拟序列用贝叶斯模型进行了融合试验。结果表明,贝叶斯融合模型能有效提取各种数据来源的有用信息进行融合,融合结果的长期变化（线性）趋势更接近器测气候序列,并在一定程度上提高了序列的精度,减小了结果的不确定性;并且,融合结果能够纠正先验分布及气候模拟数据的明显偏差,为长年代气候序列重建提供了一个可行的思路。      

由中国历史气候记录对季风导致唐朝灭亡说的质疑

2007年1月4日杂志发表了Yancheva等10人的题为"Influence of the intertropical convergence zone on the East-Asian monsoon"(热带辐合带对东亚季风的影响)的论文[1],这是德国波兹坦地学研究中心气候动力与沉积学科的主管豪格(G.H.Haug)率领的科研小组的一项成果,认为是季风的变化引起的长期干旱导致了唐朝的灭亡.     

结合历史资料的数值天气预报误差订正

运用基于历史资料的模式距平积分订正(ANO)方法,结合欧洲中心的ERA-interim再分析资料和0.1度分辨率的中国地面自动站与CMORPH卫星反演降水资料融合逐时降水产品,对高分辨非静力WRF模式的数值预报结果进行订正试验,检验了ANO方法对灾害性天气、尤其持续性强降水预报的订正改进效果。对1983-2013年7月中旬四川地区数值预报结果订正前后与观测和再分析数据的比较表明,ANO方法不仅在环流场的预报订正试验中有较为显著的效果,对模式降水预报结果也有改进,能够有效提高模式对强降水的预报精度和评分、减小预报偏差,其中对2013年7月8—13日高分辨预报结果的ANO订正试验发现,订正环流场各变量都有改进,其中位势高度距平相关系数ACC平均提高了7.8%,均方根误差RMSE平均降低了55.7%,降水(特别是暴雨以上量级)的ETS评分和TS评分也有不同程度的提高,并得到多年独立样本的高分辨数值预报订正结果的支持。     

使用JJQ1型信号模拟器校准数据采集器问题分析

JJQ1型信号模拟器是中国气象局下发到各省的功能较为完善的自动气象站信号模拟器,从配发各省至今已有3年的时间了,尚没有省份使用该信号模拟器正式开展采集器校准工作,导致这种情况的原因是多方面的:包括校准使用的软件不合理、各通道(尤其是模拟信号通道)之间会产生信号干扰导致校准工作耗时长效率低、模拟信号随环境温度漂移大、不能兼容多数常用的数据采集器等。通过理论及试验测试分析了以上的问题,给该信号模拟器使用者和设计研发人员提出了建议和意见。     

星载雷达在订正地基天气雷达标定误差中的应用

在雷达反射率数据定量应用中,标定误差是导致结果产生偏差的重要原因之一。星载雷达（TRMM PR）长期工作的稳定性和连续性已被验证,本文将星载雷达数据转换到S波段,通过对比星载雷达和南京雷达同时段不同高度（相对于融化层的位置）不同降水类型（层云降水或对流降水）的数据,得到两部雷达对融化层以下层云降水的观测相关性高,差异稳定。通过对比分析星载雷达和南京雷达同时段零度层以下层状云降水的观测数据,得出两部雷达反射率因子值的回归关系式。以星载雷达观测数据为基准,使用该关系式对南京雷达反射率数据进行订正,并通过雨量计数据对订正结果进行验证,结果显示使用本文订正关系式订正后雷达估计的降雨量更接近雨量计的观测值。     

Impacts of Land Degradation on Historical Temperature Records from the Sonoran Desert

Previous research revealed that severe overgrazing and resultant land degradation in the semiarid areas of northern Mexico created significantly higher temperatures in the border area. In this investigation, the temperature and precipitation records from ten homogeneous stations are identified in the arid and hyperarid areas of northwest Sonora and are compared with the records from ten stations in southwestern Arizona. Our data show that the Mexican stations are again consistently warmer than the Arizona stations when statistical controls are applied to correct for the linear or non-linear effects of latitude and/or elevation. The stations in Sonora warm at a statistically significantly faster pace than the stations in Arizona during the study period. Furthermore, and consistent with other dryland areas undergoing land degradation, the stations in Sonora reveal a significant increase in the diurnal temperature range during the summer season. Local precipitation reduces the temperature differential between nations on the time scale of days, but enhances the differential on the time scale of months and seasons. Among other findings, the results show how land degradation in dryland areas appears to influence local historical temperature records.     

利用卡尔曼滤波校准方法估算区域降水量

该文根据卡尔曼滤波校准方法估算区域降水量的原理,利用“973”项目野外观测资料对2002年6月22日的一次降水过程进行了试验研究。结果表明：卡尔曼滤波校准方法能提高雷达定量估算区域降水量的精度,并能较好地反映雷达探测到的精细降水场结构;验证了随着观测次数的增加,卡尔曼滤波校准方法估算降水量的精度越来越高。     

稳态与湍流特征测试对通量数据质量的评价

应用CO2通量、感热和潜热通量稳态测试及垂直速度积分测试相结合的湍流数据质量评价方法对锡林浩特国家气候观象台2009年全年的湍流通量观测数据进行了质量评价。结果表明,锡林浩特通量观测数据质量总体较好;80％以上数据通过质量评价为较好数据;质量评价较好的数据分布呈白天大于夜间、夏季大于冬季的特点。经过对比分析,前期数据处理能剔除大部分质量不好的数据,但应用稳态测试与湍流积分测试筛选后,数据质量仍有明显提高,能量闭合率较前期数据分析前提高2％以上。     

Bias Adjustment and Analysis of Chinese Daily Historical Radiosonde Temperature Data

The discontinuities in historical Chinese radiosonde datasets are attributed to artificial errors. In order to reflect more realistically basic conditions of the atmosphere over China and provide more reasonable radiosonde data as input to climate change analysis and to atmospheric reanalysis data assimilation systems, this paper proposes a scheme to identify breakpoints and adjust biases in daily radiosonde observations. The ongoing ECMWF Re Analysis-Interim(ERA-Interim) 12-h forecasts are used as reference series in the scheme, complemented by the ECMWF Twentieth Century Reanalysis(ERA-20 C). A series of breakpoint identification schemes are developed and combined with metadata to detect breakpoints. The Quantile-Matching(QM) method is applied to test and adjust daily radiosonde data on 12 mandatory pressure levels collected at 80 sounding stations during 1979–2013. The adjusted temperatures on mandatory levels are interpolated to significant levels for temperature adjustment on these levels. The adjustment scheme not only solves the data discontinuity problem caused by changes in observational instruments and bias correction methods, but also solves the discontinuity problem in the 1200 minus 0000 UTC temperature time series on mandatory levels at individual sounding stations. Before the adjustment, obvious discontinuities can be found in the deviation field between the raw radiosonde data and ERA-Interim reanalysis with relatively large deviations before 2001. The deviation discontinuity is mainly attributed to the nationwide upgrade of the radiosonde system in China around 2001. After the adjustment, the time series of deviations becomes more continuous. In addition, compared with the adjusted temperature data on mandatory levels over 80 radiosonde stations in China contained in the Radiosonde Observation Correction Using Reanalyses(RAOBCORE) 1.5, the dataset adjusted by the method proposed in the present study exhibits higher quality than RAOBCORE 1.5, while discontinuities still exist in the time series of temperature at 0000, 1200, and 1200 minus 0000 UTC in RAOBCORE 1.5.     

Test of Scintillometer Saturation Correction Methods Using Field Experimental Data

Saturation of large aperture scintillometer (LAS) signals can result in sensible heat flux measurements that are biased low. A field study with LASs of different aperture sizes and path lengths was performed to investigate the onset of, and corrections for, signal saturation. Saturation already occurs at \({C_n^2 \approx 0.074 D^{5/3} \lambda^{1/3} L^{-8/3}}\), where \({C_n^2}\) is the structure parameter of the refractive index, D is the aperture size, λ is the wavelength, L is the transect length, which is smaller than theoretically derived saturation limits. At a transect length of 1 km, a height of 2.5 m, and aperture ≈0.15 m the correction factor exceeds 5% already at \({C_n^2=2\times 10^{-12}{\rm m}^{-2/3}}\), which will affect many practical applications of scintillometry. The Clifford correction method, which only depends on \({C_n^2}\) and the transect geometry, provides good saturation corrections over the range of conditions observed in our study. The saturation correction proposed by Ochs and Hill results in correction factors that are too small in large saturation regimes. An inner length scale dependence of the saturation correction factor was not observed. Thus for practical applications the Clifford correction method should be applied.