ECMWF和NCEP再分析资料在青藏高原高度场变化中的对比分析

利用ECMWF和NCEP/NCAR北半球逐月平均的600 hPa、500 hPa和200 hPa高度场再分析资料,对高原地区高度场流型及量值进行对比研究.结果表明:二者在不同的再分析资料中具有一定的相似性,但仍存在着明显的区别.高度场流型的区别由低层向高层依次减小,600hPa高度场除冬季的流型基本一致外,其余三季的流...     

基于中国全球海洋预报系统(CGOFS)的全球高分辨率再分析产品评估

通过同化系统将观测资料与海洋数值模式融合得到的海洋再分析产品为海洋科学研究提供了重要的资料基础.本文采用WOA,SODA,AVISO和GLORS四种数据资料与我国自主研发的中国全球海洋预报系统(CGOFS)的气候态结果进行了对比,结果表明:CGOFS和SODA的全球海表面温度与WOA的均方根误差分别为0.51和0.43℃.CGOFS和SODA的海表面盐度与WOA的均方根误差分别为0.48和0.40 PSU;海流方面,CGOFS能较好的刻画主要大洋环流分布及赤道潜流的垂向结构;CGOFS的全球海表面高度异常与AVISO的均方根误差为0.018m;多年月平均海冰外缘线覆盖面积介于SODA和GLORS之间,海冰体积的生消规律与SODA和GLORS一致.总体来看,CGOFS全球高分辨率海洋再分析产品的气候态结果与国际同类产品基本一致,可为提升我国海洋综合科技实力提供可靠的资料保障.     

Atmospheric and Coupled Model Intercomparison in Terms of Amplitude Phase Characteristics of Surface Air Temperature Annual Cycle

A model intercomparison in terms of surface air temperature annual cycle ampitude-phase characteristics(SAT AC APC)is performed. The models included in the intercomparison belong to two groups:five atmospheric models with prescribed sea surface temperature and sea ice cover and four coupled models forced by the atmospheric abundances of anthropogenic consituents (in total six coupled model simulations). Over land, the models, simulating higher than observed time averaged SAT,also tend to simulate smaller than observed amplitude of its annual and semiannual harmonics and (outside the Tropics laterthan-observed spring and autumn moments. The models with larger(smaller) time averaged amplitudes of annual and semiannual harmonics also tend to simulate larger(smaller)interannual standard deviations. Over the oceans, the coupled models with larger interannual standard deviations of annual mean SAT tend to simulate larger interannual standard deviations of both annual and semiannual SAT harmonics amplitudes. Most model errors are located in the belts 60°-70°N and 60°-70°S and over Antarctica. These errors are larger for those coupled models which do not employ dynamical modules for sea ice.No systematic differences are found in the simulated time averaged fields of the surface air temperature annual cycle characteristics for atmospheric models on one hand and for the coupled models on the other. But the coupled models generally simulate interannual variability of SAT AC APC better than the atmospheric models (which tend to underestimate it). For the coupled models, the results are not very sensitive to the choice of the particular scenario of anthropogenic forcing.There is a strong linear positive relationship between the model simulated time averaged semiannual SAT harmonics amplitude and interannual standard deviation of annual mean SAT.It is stronger over the tropical oceans and is weaker in the extratropics. In the tropical oceanic areas, it is stronger for the coupled than for the atmospheric models.     

月动力延伸预报产品在甘肃省的释用及评估

把月动力延伸预报产品的释用方法应用在甘肃省 58个气象站点 ,将其实况回报试验结果与持续性预报和近 6～ 1 0年的业务评分进行对比 ,结果表明 ,动力释用方法预报准确率明显高于持续性预报 ,也高于业务评分。同时分析了 1月和 7月预测效果好与差的环流场特征以及甘肃省分片区域的预测评估。     

普里兹湾区域风和温度资料对比分析: 以2007 年为例

通过分析再分析资料与站点观测资料的差异评估了普里兹湾区域5 套再分析资料的风速、风向以及 温度产品。这5 套再分析资料包括欧洲中心再分析资料(ERA-I)、日本25 年再分析资料(JRA-25)、日本55 年再分析资料(JRA-55)、美国国家环境预报中心再分析资料(CFSR)和美国国家航空航天局再分析资料 (MERRA)。采用的观测资料来自两个人工观测站和三个自动气象站。月平均和季节差异分析结果表明, Mawson 站点再分析资料的风速一般小于站点风速, 其他站点再分析资料一般风速过大, 所有的站点风向与 再分析资料风向差异不大, 再分析资料的2 m 温度总体低于人工观测站的温度, 自动站和再分析资料的差 异则没有一致的差异特征。通过6 h 风速资料对比, 发现当Mawson 站点风速低于5 m·s^–1 时, 再分析资料偏 高, 当站点风速高于15 m·s^–1 时, 再分析资料偏低, 且该站点记录的极端强风次数远多于再分析资料。     

块体空气动力算法的再计算湍通量与NCEP湍通量的比较

以NCEP资料提供的水文气象参数作为输入量,利用4种块体空气动力算法重新计算了动量和热量通量,与相应的NCEP自身提供的湍通量进行了比较分析,发现再计算动量、感热和潜热通量的偏差值随风速增加而增大;在中高风速下,再计算动量通量的相对误差较小,其他情况下再计算动量、感热和潜热通量的相对误差最高能达到50%左右;相对误差一般随纬度的增大而增大,表明两者之间存在不协调性。研究还表明,改进后的NCEP2资料与NCEP1资料相比,这种不协调性并没有得到改善。     

GHCN-CAMS和CMFD两种尺度再分析资料对宁夏气温反映能力评估

再分析资料能有效弥补实际观测数据时空分布不均的缺陷,开展再分析资料区域适应性评估对地气过程研究、气候分析等具有重要意义。论文利用宁夏24个气象观测站的平均气温,从2种空间尺度(0.5°×0.5°和0.1°×0.1°)和2种时间尺度(年、月),采用偏差、绝对偏差、均方根误差和相关系数等多个统计指标,评估了再分析资料对宁夏地区地面气温的反映能力。结果表明：① GHCN-CAMS(Global Historical Climatology Network and the Climate Anomaly Monitoring System)和CMFD(China Meteorological Forcing Dataset)2套再分析资料对宁夏气温的反映能力整体上均较强,前者对宁夏气温略高估,后者略低估;② 年和月2种时间尺度上,2种尺度的再分析资料存在阶段性正偏差和负偏差,且年尺度上的相关性好于月尺度的;③ 2套再分析资料对下垫面主要为农田(压砂种植)的气温均存在冷季高估、暖季低估的情况,对城镇两者总体均低估,对草地整体表现为CMFD在冷季低估、暖季略高估,而GHCN-CAMS在冷季高估、暖季低估。总体看,空间分辨率较高的CMFD再分析资料对宁夏气温的反映能力更好一些。     

世界海洋蒸发波导时空统计规律研究

The statistical features of the evaporation duct over the global ocean were comprehensively investigated with reanalysis data sets from the National Centers for Environmental Prediction.These data sets have time and spatial resolutions of 1 h and 0.313°×0.312°,respectively.The efficiency of the analysis was evaluated by processing weather buoy data from the Pacific Ocean and measuring propagation loss in the Yellow Sea of China.The distribution features of evaporation duct height(EDH) and the related meteorological factors for different seas were analyzed.The global EDH is generally high and demonstrates a latitudinal distribution for oceans at low latitudes.The average EDH is approximately 11 m over oceans beside the equator with a latitude of less than 20°.The reasons for the formation of the global EDH features were also analyzed for different sea areas.     

长时间序列多源土壤湿度产品在中国地区的比较分析

研究利用实测数据对遥感产品(ECV CCI)、全球陆面同化系统产品(GLDAS/CLM、NOAH2.7、NOAH3.3、VIC、MOSAIC)、再分析资料(ERA-Interim、NCEP/DOE)等不同来源的8套长时间序列土壤湿度产品进行时空比较。结果表明:上述产品均可以模拟出中国不同区域土壤湿度的空间分布;从各产品平均态与实测数据的偏差、均方根误差、相关系数统计结果来看,NOAH模式和ERA-Interim表现最好,MOSAIC和NCEP/DOE与实测相差较大;从区域尺度上来看,所有产品在东北区域表现最好,在华南、西南南区和西北西区较差;ERA-Interim有效的模拟了土壤湿度的年际变化。     

Evaluation and hydrological application of precipitation estimates derived from PERSIANN‐CDR,TRMM 3B42V7, and NCEP‐CFSR over humid regions in China

Satellite‐based and reanalysis quantitative precipitation estimates are attractive for hydrologic prediction or forecasting and reliable water resources management, especially for ungauged regions. This study evaluates three widely used global high‐resolution precipitation products [Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks‐Climate Data Record (PERSIANN‐CDR), Tropical Rainfall Measuring Mission 3B42 Version 7 (TRMM 3B42V7), and National Centers for Environment Prediction‐Climate Forecast System Reanalysis (NCEP‐CFSR)] against gauge observations with seven statistical indices over two humid regions in China. Furthermore, the study investigates whether the three precipitation products can be reliably utilized as inputs in Soil and Water Assessment Tool, a semi‐distributed hydrological model, to simulate streamflows. Results show that the precipitation estimates derived from TRMM 3B42V7 outperform the other two products with the smallest errors and bias, and highest correlation at monthly scale, which is followed by PERSIANN‐CDR and NCEP‐CFSR in this rank. However, the superiority of TRMM 3B42V7 in errors, bias, and correlations is not warranted at daily scale. PERSIANN‐CDR and 3B42V7 present encouraging potential for streamflow prediction at daily and monthly scale respectively over the two humid regions, whilst the performance of NCEP‐CFSR for hydrological applications varies from basin to basin. Simulations forced with 3B42V7 are the best among the three precipitation products in capturing daily measured streamflows, whilst PERSIANN‐CDR‐driven simulations underestimate high streamflows and high streamflow simulations driven by NCEP‐CFSR mostly are overestimated significantly. In terms of extreme events analysis, PERSIANN‐CDR often underestimates the extreme precipitation, so do extreme streamflow simulations forced with it. NCEP‐CFSR performs just the reverse, compared with PERSIANN‐CDR. The performance pattern of TRMM 3B42V7 on extremes is not certain, with coexisting underestimation and overestimation. Copyright © 2016 John Wiley & Sons, Ltd.