湖北省梅雨期降水集中度和集中期研究

利用黄石市2005年以来建设的95个区域气象站和原有的3个国家气象站降水资料,选取黄石国家气象站为基准点,采取各站候降水量与黄石站气温等12个要素进行逐步回归的方法,模拟出1958年至各站建站前的候降水量,使各站建站前缺测的月、年等时间尺度降水资料得以插补。并采用REOF方法分析了黄石市年降水量的时空变化特征,按照取绝对值最大的特征值所处序号为站点分类值的区划方法,将黄石市划分为丘陵及水体影响区（Ⅰ区）和山地陆面影响区（Ⅱ区）两个区域。结果表明：（1）黄石市年降水量年代际变化明显,20世纪60年代至90年代降水量逐渐增多,21世纪初明显偏少,2010年至今恢复至20世纪80-90年代的水平;（2）黄石市年降水量具有明显的地域特征,年降水受地形的影响较大,西南部山区年降水量大于丘陵区和大型水体影响区;（3）Ⅰ区和Ⅱ区降水强度同步的年数占72%,不同步的年数占28%。

     

粤北地区导线覆冰气象特征与标准厚度推算

利用广东省乐昌高山气象站1972—1978年观冰资料和气候资料,分析了粤北地区导线覆冰的气象特征,建立了导线覆冰标准冰厚的气象推算模型。根据乐昌国家气象站的历史资料,对乐昌高山气象站的气候资料进行订正延长,构建了乐昌高山气象站覆冰年极值长年代序列,并推算出离地不同高度各重现期的标准冰厚值。结果表明,粤北地区导线覆冰主要发生在1月,其次为2月和12月,平均覆冰期在90天左右,最长覆冰期可达131天以上。主导风向、日最低气温、日降水量是影响导线覆冰厚度的主要气象因素。标准冰厚的年极值序列服从极值I型概率分布,历史上的最大导线覆冰值出现在2008年1月26日,2m高度标准冰厚达64.4mm,15m高度标准冰厚达92.7mm,与2008年冰灾实况调查的覆冰厚度(标准冰厚)115mm较为接近。     

基于均一化观测序列的京津冀地区气候变化格局分析

利用1960~2015年京津冀地区88个国家级气象站观测资料（包括日平均气温、日最高气温、日最低气温、日降水、日平均风速等）,使用MASH（Multiple Analysis of Series for Homogenization）方法剔除台站迁址、仪器变更等因素所致偏差后,生成均一化的观测资料集。基于新资料集计算了各站气温、降水和凤速序列的线性趋势和Morlet小波等统计特征,分析了京津冀地区气候变化格局。结果表明:MASH方法能较准确地检测并校订观测序列中迁站、仪器变更等因素所导致的非均一性;1960~2015年期间京津冀年平均气温显著上升,上升幅度为0.261℃/10 a;降水减少,平均减少11.27 mm/10 a;风速显著减小,平均减小0.193 m s-1（10 a）-1。     

兰州站气候资料序列均一性的初步分析

气候资料的均一性是研究气候变化的前提条件。以兰州站为例,应用SNHT方法对该站的气候资料序列进行均一性检验,首先对降水、平均气温、最高气温、最低气温、平均风速和日照时数几个气象要素进行非均一性检验,然后根据历史台站沿革等元数据信息进行原因分析。结果表明,兰州站平均风速资料与其邻站相关系数低,未通过显著性检验。降水、气温、最高气温、最低气温、日照与邻站的相关系数都达到99％的显著水平,且都存在不均一性,其原因主要有台站的迁移、仪器的更换、统计方法的变化以及城市热岛效应等,完整详细的元数据信息是均一性研究的重要基础。     

昆明长水机场气候特征分析

利用昆明市1951—2010年逐日气象数据,采用回归分析法和Mann-Kendall突变分析法进行分析和检验,确定了昆明市极端降水和极端温度天气事件。在此基础上,对昆明长水机场极端天气背景下大雾天气航班安全运行开展研究,并在对比昆明长水机场与原巫家坝机场大雾特点的基础上,制定出航班安全运行的应对措施。研究表明,近几年昆明市极端温度和极端降水事件呈现增多趋势;因地形原因,长水机场出现大雾的频率远高于原巫家坝机场;大雾造成的低能见度天气背景下,航班的安全运行需要航空公司各部门的通力协作。     

甘肃崆峒站新旧址对比观测资料分析

为了解甘肃崆峒国家基本气象站新旧址气象要素对比观测数据差异,选用2016年1～12月新站和旧站气温、气压、相对湿度、风向风速、降水量等要素资料进行对比分析,重点利用均值差异、相关与回归、显著性检验等统计方法分析了新旧测站气温差异及产生原因,结果表明：新址气温、气压均低于旧址,风速高于旧址,降水量、相对湿度差异大,变化无规律,其产生的主要原因是地理位置、海拔高度及观测场周边环境的不同造成;新址与旧址气温存在高度正相关,两站气温差异不显著,可以合并计算,研究结果可为资料使用者提供订正的依据。     

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。      

2019年韶关“5·18”局地特大暴雨极端性成因分析

2019年5月18日,广东省韶关市出现了局地特大暴雨,刷新了韶关有气象记录以来的雨量记录。利用常规观测资料、区域气象自动站观测资料、韶关双偏振多普勒天气雷达资料,以及NCEP 1 °×1 °再分析资料对本次过程进行详细分析,探讨本次过程发生的极端性成因。(1) 本次过程是粤北历史罕见的局地暖区突发性特大暴雨过程,天气尺度的背景场较弱,极端性条件不显著,但能从中尺度分析场分析出暴雨潜势。(2) 暴雨发生之前,韶关一直处于偏南暖湿气流控制的区域,并且随着对流抑制减小为0,对流有效位能增强,自由对流高度下降至近地面,使得气块更容易被强迫抬升。(3) 多个单体持续发展与合并,出现“列车效应”,近地面冷池维持向南楔入,低层西南风加强叠加于冷池上导致强风速辐合辐散区和中气旋的出现,是维持强回波持续发展的重要原因;回波呈暖区降水的垂直结构特性,也呈现出近地面层冷池对暖湿气流强迫抬升的结构特征,侧面说明了强降水触发机制。(4) 地形对对流触发和暴雨的增幅有重要影响,峡谷和喇叭口地形加强了偏南气流的汇入及辐合作用,山前迎风坡除了地形抬升作用外,位于山前的地面辐合线对于对流既有触发又有加强与维持的作用。(5) 山前强水平温度梯度为对流发生提供了有利的环境条件,当初生对流出现降雨之后,水平温度梯度进一步加强,形成了温度梯度与对流强度之间的正反馈过程,因而对流持续发展与维持。(6) 对于此类突发的短历时强降水造成的暖区暴雨,监测和短临预警仍然是主要手段。      

神农架及周边地区夏季气象要素时空特征初步分析

采用2010—2011 年6—8 月神农架及周边地区高山自动气象站观测的逐时资料,初步分析了神农架及周边地区夏季降水、气温、风场等气象要素的时空分布特征。结果发现：降水时数基本呈现随着海拔的增高而增多的趋势。东北坡和东南坡降水时数日变化整体均呈单峰型变化趋势,峰值出现在午后至傍晚,西南坡降水时数的日变化分布均匀。西南坡最高气温出现时间偏晚。多数站点2010—2011 年夏季盛行风向具有一致性。局地风场受地形影响很大,日变化明显,可能由山谷风效应引起。海拔较高的站点水汽昼夜变化较大,海拔较低的站点水汽昼夜变化较小。东北坡松柏站夜间盛行西北风,水汽大幅度减少,白天盛行东南风,水汽增加,可能是午后降水时数明显增多的原因之一。     

陕北植被变化遥感监测及对径流的影响

陕北北部是我国水土流失最为严重的地区,年输入黄河的泥沙量占全河的38%。1999年实施退耕还林草工程后,退耕还林草面积达9617.2 km2。利用1998-2004年NOAA卫星遥感资料,计算陕北北部地区归一化植被指数,发现陕北植被指数增幅在50%-200%之间,其中吴旗县增幅最大。对延安北部及榆林市1998-2004年降水量资料分析,得出植被指数增加是退耕还林草工程初见成效,不是由于降水变化引起的。利用1980-2004年吴旗县气象站观测的降水量和水文站所测径流量进行时间序列相关分析、典型年对比分析,得出该县植被变化对年径流量产生了影响,年径流量和泥沙量减少近一半,对保持水土有积极意义。     

High-resolution precipitation and temperature downscaling for glacier models

The spatial resolution gap between global or regional climate models and the requirements for local impact studies motivates the need for climate downscaling. For impact studies that involve glacier modelling, the sparsity or complete absence of climate monitoring activities within the regions of interest presents a substantial additional challenge. Downscaling methods for this application must be independent of climate observations and cannot rely on tuning to station data. We present new, computationally-efficient methods for downscaling precipitation and temperature to the high spatial resolutions required to force mountain glacier models. Our precipitation downscaling is based on an existing linear theory for orographic precipitation, which we modify for large study regions by including moist air tracking. Temperature is downscaled using an interpolation scheme that reconstructs the vertical temperature structure to estimate surface temperatures from upper air data. Both methods are able to produce output on km to sub-km spatial resolution, yet do not require tuning to station measurements. By comparing our downscaled precipitation (1 km resolution) and temperature (200 m resolution) fields to station measurements in southern British Columbia, we evaluate their performance regionally and through the annual cycle. Precipitation is improved by as much as 30% (median relative error) over the input reanalysis data and temperature is reconstructed with a mean bias of 0.5°C at locations with high vertical relief. Both methods perform best in mountainous terrain, where glaciers tend to be concentrated.     

Temperature and precipitation fluctuations in the Czech Republic during the period of instrumental measurements

The history of early meteorological observations using instruments in the Czech Lands is described (the longest temperature series for Prague-Klementinum starts in 1775, precipitation series for Brno in 1803). Using the PRODIGE method, long-term monthly temperature and precipitation series from selected secular stations were homogenised (for 10 and 12 stations, respectively). All the seasonal and annual temperature series for the common period 1882–2010 show a significant positive linear trend with accelerated warming from the 1970s onwards. No significant linear trends were disclosed in the series of seasonal and annual precipitation totals. Correlation coefficients between the Czech series analysed decrease as distances between measuring stations increase. A sharper decrease of correlations for precipitation totals displays much weaker spatial relationships than those for mean temperatures. The highest correlations between all stations appeared in 1921–1950, the lowest in 1891–1920 (temperature) and 1981–2010 (precipitation). Wavelet analysis reveals that very distinct annual cycles as well as the slightly weaker semi-annual ones are better expressed for temperature series than for precipitation. Statistically significant cycles longer than 1?year are temporally unstable and sporadic for precipitation, while in the temperature series cycles of 7.4–7.7 and 17.9–18.4?years were recorded as significant by all stations in 1882–2010 (quasi-biennial cycle of 2.1–2.2?years for half the stations). Czech homogenous temperature series correlate best with those of the Northern Hemisphere for annual, spring and summer values (with significant correlation coefficients between 0.60 and 0.70), but this relation is temporally unstable. Circulation indices, such as the North Atlantic Oscillation Index (NAOI) and the Central European Zonal Index (CEZI), may explain the greater part of Czech temperature variability, especially from December to March and for the winter; however, this relationship is much weaker, or even random, for precipitation series. Further, relationships with the Southern Oscillation Index (SOI) are weak and random. Relatively weak coincidences exist between statistically significant cycles in the Czech series and those detected in NAOI, CEZI and SOI series.     

Reconstruction of hydrometeorological time series and its uncertainties for the Kaidu River Basin using multiple data sources

This paper tried to reconstruct the time series (TS) of monthly average temperature (MAT), monthly accumulated precipitation (MAP), and monthly accumulated runoff (MAR) during 1901–1960 in the Kaidu River Basin using the Delta method and the three-layered feed forward neural network with backpropagation algorithm (TLBP-FFNN) model. Uncertainties in the reconstruction of hydrometeorological parameters were also discussed. Available monthly observed hydrometeorological data covering the period 1961–2000 from the Kaidu River Basin, the monthly observed meteorological data from three stations in Central Asia, monthly grid climatic data from the Climatic Research Unit (CRU), and Coupled Model Intercomparison Project Phase 3 (CMIP3) dataset covering the period 1901–2000 were used for the reconstruction. It was found that the Delta method performed very well for calibrated and verified MAT in the Kaidu River Basin based on the monthly observed meteorological data from Central Asia, the monthly grid climatic data from CRU, and the CMIP3 dataset from 1961 to 2000. Although calibration and verification of MAP did not perform as well as MAT, MAP at Bayinbuluke station, an alpine meteorological station, showed a satisfactory result based on the data from CRU and CMIP3, indicating that the Delta method can be applied to reconstruct MAT in the Kaidu River Basin on the basis of the selected three data sources and MAP in the mountain area based on CRU and CMIP3. MAR at Dashankou station, a hydrological gauge station on the verge of the Tianshan Mountains, from 1961 to 2000 was well calibrated and verified using the TLBP-FFNN model with structure (8,1,1) by taking MAT and MAP of four meteorological stations from observation; CRU and CMIP3 data, respectively, as inputs; and the model was expanded to reconstruct TS during 1901–1960. While the characteristics of annual periodicity were depicted well by the TS of MAT, MAP, and MAR reconstructed over the target stations during the period 1901–1960, different high frequency signals were captured also. The annual average temperature (AAT) show a significant increasing trend during the 20th century, but annual accumulated precipitation (AAP) and annual accumulated runoff (AAR) do not. Although some uncertainties exist in the hydrometeorological reconstruction, this work should provide a viable reference for studying long-term change of climate and water resources as well as risk assessment of flood and drought in the Kaidu River Basin, a region of fast economic development.     

九华山区云水资源状况分析

九华山区及周边的地形是以天台至大花台为主脉,四周有低山丘陵合围。复杂地形下各地气候差异明显。应用1980—2010年近30 a观测资料及山区不同高度的自动站数据,运用大气边界层理论及多项式拟合、相关分析等数理统计方法,研究山区与丘陵云水资源的差异。结果表明：地形的动力作用影响了山区局地水汽的输送条件;山区下垫面对降水的增雨作用较为明显,强度越大的降水,其增强作用就越明显,地形对降水的平均贡献率为37.6%。山区与周边降水分布很不均匀,九华山年平均降水量比周边区域多34.1%,山区水资源远大于周边丘陵地区,前者是后者的3.4倍,且一年四季有盈余,但降水量季节分布不均,秋季是最易出现干旱缺水的季节。缓解山区的旱情要以开源蓄水为主,辅以必要的人工增雨。     

锡林浩特站址迁移对气温资料的影响

以多年来观测场周边环境变化较小且未迁过站的阿巴嘎旗为基本参照站,利用差值法,与锡林浩特气温序列资料进行对比分析,结果表明:自2002年锡林浩特气象观测站迁址后气温序列出现不均一性,对气温资料序列的连续性产生了影响。其中冷季和最低气温差值大,暖季和最高气温差值小,说明站址变迁对低温序列资料影响较大。     

地面气象观测站自动检测系统研究

为了解决目前的计量检定标准设备和方法不适于地面气象观测站仪器,检测的自动化水平及工作效率低等矛盾,研究设计了地面气象观测站自动检测系统,特点是将地面气象观测站的温度、湿度、大气压力、风速风向和降水等传感器和地面气象观测站的数据采集器分开进行性能的自动检测.传感器自动检测系统采用多通道设计,可同时进行多个传感器的自动检测并自动输出检测结果.数据采集器自动检测系统可以对气象台站使用的各种不同的地面气象观测站数据采集器系统进行性能测试.文章所设计的地面气象观测站自动检测系统提高了地面自动观测仪器的检测效率,确保了各台站的地面气象自动观测仪器观测数据的准确可靠.     

Catchment precipitation processes in the San Francisco valley in southern Ecuador: combined approach using high-resolution radar images and in situ observations

The precise estimation of precipitation quantities in tropical mountain regions is in great demand by ecological and hydrological studies, due to the heterogeneity of the rainfall distribution and the lack of meteorological station data. This study uses radar images and ground station data to provide the required high-resolution precipitation maps. Also wind data are taken into account, due to its influence on the precipitation formation and to demonstrate the relation between synoptic wind, topography and the precipitation distribution inside small mountain valleys. The study analyses the rainfall distribution and amounts of 4 days inside the San Francisco Valley, a small catchment in the tropical Andes of southern Ecuador, representing different seasons and the typical atmospheric flows, which are correlated to the annual precipitation map. The results show that the rainfall distribution and amounts are generally defined by the wind direction and velocity, besides the topographic location in relation to the main barriers and pathways. The dominant wind direction causes a division of the catchment in a wetter eastern and a dryer western part. Moreover, the annual seasons are reversed; the main rainy season for the eastern part occurs between June and August, while the western part reaches the precipitation maximum between January and March. This may have influence on the species composition at the different slopes and the annual hydrological cycle inside the catchment.     

1961—2009年辽河流域水文气象要素变化特征

依据1961—2009年辽河流域5个气象观测站点逐日降水和气温观测资料,运用非参数检验方法（Mann-Kendall法）,对辽河流域降水和气温的变化趋势进行了分析。利用2006—2010年夏季共162d降水日的铁岭站日降水量与铁岭水文站径流量资料,探讨了日降水量与径流量之间的相关关系。结果表明：辽河流域年降水量减少趋势明显,降水量偏少年份明显增加,其主要原因为占全年降水量65%的夏季降水以7.4 mm/10 a的气候趋势倾向率递减,呈现出明显的减少趋势;辽河流域的年平均气温是在波动中逐渐上升的,且升温趋势明显,春季呈明显的升温趋势,夏季略有下降,秋季变化不大,冬季是气温上升最明显的季节;日降水量与径流量存在正相关关系,且日降水量与降水第二日的径流量相关显著。     

Spatiotemporal dynamics of the Urals’ climate in the second half of the 20th century

Dynamics of the surface air temperature and amount of precipitation in the Polar, Northern, and Southern Urals in the 20th century is analyzed. Charts of the temperature distribution in the Urals for the period from 1961 to 2000, taking into account the relief, are plotted in the geographical informational system on the basis of data of instrumental measurements at meteorological stations with the use of the multiple regression analysis and raster modeling. The northeastern direction of the warming gradient and increase of falling precipitations in the period under review is established. Time series of anomalies of the average annual air temperature and amount of precipitation in the 20th century at three meteorological stations, situated in the Polar, Northern, and Southern Urals, are analyzed. The tendency of the growth of anomalies of the average annual temperature and total amount of precipitation is revealed.