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1.
Comparative energetics of ERA-40, JRA-25 and NCEP-R2 reanalysis, in the wave number domain 总被引：1，自引：0，他引：1
The European Centre for Medium-Range Weather Forecasts 40-year Reanalysis (ERA-40), the Japan Meteorological Agency and Central Research Institute of Electric Power Industry 25-year Reanalysis (JRA-25), and the National Centers for Environmental Prediction and Department of Energy AMIP-II Reanalysis (NCEP-R2) are intercompared through a global energetics analysis for all seasons.Overall, the Lorenz energy cycle is consistent among the three datasets. The flow of energy and the peaks and slopes in the spectra of the various components agree between the three reanalysis. Additionally, the temporal variability of the energy cycle terms shows consistency between the three reanalysis. Most differences between the three reanalysis are related to the magnitudes of energy forms and energy conversion/transfer rates at each wave number, generally following the relation ERA−40>JRA−25>NCEP−R2, and mainly located in the Southern Hemisphere. The best agreement between the three datasets is found for northern winter. Differences between the three datasets are greater for the other seasons, being greatest for northern summer. In general, these discrepancies are fairly modest, being likely due to the different model biases and resolutions, and the different data assimilation methods used by the respective reanalysis systems. The energetics of the three reanalysis become closer to each other in more recent years, which is likely due to the increase in the number of observations assimilated in the reanalysis.The NCEP-R2 reanalysis spectrum is smoother than those of ERA-40 and JRA-25, likely due to filtering and to its lower resolution model. The spectra show a rapid decrease for short waves in NCEP-R2 (n=36) and ERA-40 (n=63), as a consequence of filtering. The energy source in the nonlinear wave–wave interactions of kinetic energy, L(n), has a narrower spectral range in NCEP-R2 than in the other datasets. Energetics from the newer JRA-25 reanalysis is generally closer to that of ERA-40, with some exceptions as is the case of zonal–wave interactions of kinetic energy, M(n), for synoptic waves, or for eddy available potential energy, AE, in the lower troposphere, for which JRA-25 is closer to NCEP-R2. 相似文献
2.
We dynamically downscaled Japanese reanalysis data (JRA-25) for 60 regions of Japan using three regional climate models (RCMs): the Non-Hydrostatic Regional Climate Model (NHRCM), modified RAMS version 4.3 (NRAMS), and modified Weather Research and Forecasting model (TWRF). We validated their simulations of the precipitation climatology and interannual variations of summer and winter precipitation. We also validated precipitation for two multi-model ensemble means: the arithmetic ensemble mean (AEM) and an ensemble mean weighted according to model reliability. In the 60 regions NRAMS simulated both the winter and summer climatological precipitation better than JRA-25, and NHRCM simulated the wintertime precipitation better than JRA-25. TWRF, however, overestimated precipitation in the 60 regions in both the winter and summer, and NHRCM overestimated precipitation in the summer. The three RCMs simulated interannual variations, particularly summer precipitation, better than JRA-25. AEM simulated both climatological precipitation and interannual variations during the two seasons more realistically than JRA-25 and the three RCMs overall, but the best RCM was often superior to the AEM result. In contrast, the weighted ensemble mean skills were usually superior to those of the best RCM. Thus, both RCMs and multi-model ensemble means, especially multi-model ensemble means weighted according to model reliability, are powerful tools for simulating seasonal and interannual variability of precipitation in Japan under the current climate. 相似文献
3.
4.
Evaluation of Reanalysis Products with in situ GPS Sounding Observations in the Eastern Himalayas 
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下载免费PDF全文 Previous studies have shown that reanalysis products contain large uncertainties in the Tibetan Plateau(TP),and the biases are location dependent.Therefore,these products must be evaluated with in situ observations prior to their applications.In this study,the authors compare the results of several reanalysis projects with independent sounding observations recorded in the Yarlung Tsangpo River valley in the Eastern Himalayas in June 2010.These reanalysis projects include Climate Forecast System Reanalysis(CFSR),Interim European Centre for Medium Range Weather Forecasts Reanalysis(ERA- Interim),Japanese 25-year Reanalysis(JRA-25),Modern Era Retrospective Analysis for Research and Applications(MERRA),National Center for Environmental Prediction and the Department of Energy Reanalysis 2(NCEP-R2),and NCEP Final Analysis(FNL).Statistical quantities such as average,mean bias(MB),root-mean-square difference(RMSD),and correlation coefficient(R) of temperature,specific humidity,u-wind,and v-wind between 100 hPa and 650 hPa were calculated.The authors determined that the performance of each product differed with variables at different levels.The average profiles of the variables were captured by the reanalysis products,with large biases appearing at lower levels.ERA-Interim and NCEP-R2 showed the best and worst performances,respectively,for all variables.This study suggests that users should select appropriate reanalysis products according to their specific purposes for TP research. 相似文献
5.
The 2m temperature (T2m) and precipitation from five regional climate models (RCMs), which participated in the ENSEMBLES project and were integrated at a 25-km horizontal resolution, are compared with observed climatological data from 13 stations located in the Croatian coastal zone. The twentieth century climate was simulated by forcing RCMs with identical boundary conditions from the ERA-40 reanalysis and the ECHAM5/MPI-OM global climate model (GCM); climate change in the twenty-first century is based on the A1B scenario and assessed from the GCM-forced RCMs’ integrations. When forced by ERA-40, most RCMs exhibit cold bias in winter which contributes to an overestimation of the T2m annual cycle amplitude and the errors in interannual variability are in all RCMs smaller than those in the climatological mean. All models underestimate observed warming trends in the period 1951–2010. The largest precipitation biases coincide with locations/seasons with small observed amounts but large precipitation amounts near high orography are relatively well reproduced. When forced by the same GCM all RCMs exhibit a warming in the cold half-year and a cooling (or weak warming) in the warm period, implying a strong impact of GCM boundary forcing. The future eastern Adriatic climate is characterised by a warming, up to +5 °C towards the end of the twenty-first century; for precipitation, no clear signal is evident in the first half of the twenty-first century, but a reduction in precipitation during summer prevails in the second half. It is argued that land-sea contrast and complex coastal configuration of the Croatian coast, i.e. multitude of island and well indented coastline, have a major impact on small-scale variability. Orography plays important role only at small number of coastal locations. We hypothesise that the parameterisations related to land surface processes and soil hydrology have relatively stronger impact on variability than orography at those locations that include a relatively large fraction of land (most coastal stations), but affecting less strongly locations at the Adriatic islands. 相似文献
6.
应用台站观测资料对ERA-40、NCEP/NCAR、NCEP/DOE和JRA-25等几种再分析地表(2m)气温资料在中国不同区域、不同年代和季节的气候均值、年际变化和变率特征及其气候趋势等所反映出来的适用性问题进行了系统评估.结果表明,几种再分析产品在全国大多数地区的气候变化研究中都具有一定的合理性,特别是1979年以后的资料可靠性更高一些.但相比而言,它们在冬季的可信度一般要高于夏季,东部地区的可信度一般要高于西部地区;ERA-40和JRA-25再分析产品的适用性要高于NCEP/NCAR和NCEP/DOE再分析产品;其中,JRA-25在均值、年际变化和变率特征的描述上具有更高的可靠性,而ERA-40在长期气候变化趋势(44年)的描述上则要明显优于NCEP/NCAR再分析产品. 相似文献
7.
三种再分析气温资料在中国西部地区的可信度评价 总被引：1，自引：0，他引：1
钞振华 《南京气象学院学报》2011,34(2):162-169
再分析资料质量检验和可信度分析是其合理使用的必要前提,是提高气候变化研究成果可靠性的根本保证,为了评价NCEP-II、ERA-40和JRA-25三种再分析资料在中国西部地区的可信度,研究对比分析了2m气温产品的质量。结果表明,这三种再分析气温产品都能较好地反映中国西部地区气温的空间分布特征,在地形复杂区域与站点气温的差异比较大,而在地势相对平缓的地区这三种再分析资料都能提供高质量的气温产品。由于同化了地面观测资料,ERA-40、JRA-25气温产品的可信度相对较高,且能够提供更为详尽的大尺度气温变异性。总体上,ERA-40的质量优于其他两种再分析资料。 相似文献
8.
多套大气再分析资料的南亚高压强度变化特征及其与海表温度异常关系的比较分析 总被引：1，自引：0，他引：1
以往的研究中多采用NCE/NCAR再分析资料来讨论南亚高压的变化特征及其与海表温度的关系,鉴于其分析结果具有一定的片面性,本文采用ERA40、ERA—Interim、NCEWNCAR、NCEP—DOE和JRA．25五套再分析资料,以及应用全球、热带印度洋和热带大西洋1978--2008年逐月观测海表温度分别驱动NCARCAM5．1全球大气环流模式的数值模拟结果,比较了它们的夏季南亚高压强度变化特征及其与海表温度的关系。再分析资料问的比较结果表明,NCEWNCAR、NCEP—DOE两套再分析资料与ERA40、ERA—Interim、JRA-25三套再分析资料的南亚高压强度变化在20世纪70年代末至90年代初存在非常明显的差异,前两套再分析资料揭示的该时段南亚高压强度显著偏高,可能是不真实的,进而导致南亚高压强度与海表温度异常的关系与后三套再分析资料的结果差异明显。ERA40、ERA—Interim和JRA-25三套再分析资料和数值试验结果均表明,20世纪70年代末以后,夏季南亚高压强度异常与前期冬季、春季及同期夏季的热带印度洋海表温度异常关系持续密切,表明热带印度洋是影响夏季南亚高压强度变化的关键海区。当热带印度洋偏暖时,热带地区对流层温度增暖,南亚高压强度增强、面积增大、南扩、东伸西展,反之亦然。 相似文献
9.
Xavier Fettweis Hubert Gallée Filip Lefebre Jean-Pascal van Ypersele 《Climate Dynamics》2005,24(6):623-640
The 1990 and 1991 ablation seasons over Greenland are simulated with a coupled atmosphere-snow regional climate model with
a 25-km horizontal resolution. The simulated snow water content allows a direct comparison with the satellite-derived melt
signal. The model is forced with 6-hourly ERA-40 reanalysis at its boundaries. An evaluation of the simulated precipitation
and a comparison of the modelled melt zone and the surface albedo with remote sensing observations are presented. Both the
distribution and quantity of the simulated precipitation agree with observations from coastal weather stations, estimates
from other models and the ERA-40 reanalysis. There are overestimations along the steep eastern coast, which are most likely
due to the “topographic barrier effect”. The simulated extent and time evolution of the wet snow zone compare generally well
with satellite-derived data, except during rainfall events on the ice sheet and because of a bias in the passive microwave
retrieved melt signal. Although satellite-based surface albedo retrieval is only valid in the case of clear sky, the interpolation
and the correction of these data enable us to validate the simulated albedo on the scale of the whole Greenland. These two
comparisons highlight a large sensitivity of the remote sensing observations to weather conditions. Our high-resolution climate
model was used to improve the retrieval algorithms by taking more fully into account the atmosphere variability. Finally,
the good agreement of the simulated melting surface with the improved satellite signal allows a detailed estimation of the
melting volume from the simulation. 相似文献
10.
Comparison of surface variables from ERA and NCEP reanalysis with station data over eastern China 总被引：2，自引：1，他引：1
Zhaofei Liu Zongxue Xu Zhijun Yao Heqing Huang 《Theoretical and Applied Climatology》2012,107(3-4):611-621
This study compared precipitation, mean air temperature (MAT) and mean sea level pressure (MSLP) from two widely used reanalysis datasets (ERA-40 and NCEP) with those from observed stations across eastern China. The evaluation was based on a comparison of both temporal and spatial variability and included several assessment criteria such as the mean values, normalized root mean square error, Mann–Kendall test, empirical orthogonal functions (EOFs) and probability density functions. The results showed that both the ERA-40 and NCEP datasets could capture temporal and spatial variability of the observed precipitation, MAT and MSLP over eastern China. The results showed that the two reanalysis datasets performed better for MAT and MSLP than for precipitation. Overall, the two reanalysis datasets revealed reasonable agreement with observations according to the evaluation. ERA-40 was better at capturing the temporal and spatial distributions for these three variables than NCEP, especially for MAT and MSLP. NCEP tended to overestimate the annual precipitation for both mean and extreme values, while ERA-40 tended to underestimate it, particularly for extreme values. The two reanalysis datasets performed better in the east and northeast regions of the study area than in other regions for capturing the temporal variability of MAT and MSLP. ERA-40 was poor at capturing the temporal variability of precipitation in northeastern China. According to the trend analysis, the two reanalysis datasets showed lower trends for MAT and precipitation and higher trends for MSLP. Both ERA-40 and NCEP had larger explained variances for the first two EOFs than the observed precipitation. This implies that both reanalysis datasets tend to simulate a more uniform spatial distribution for precipitation in the study area. 相似文献
11.
中国区域ERA-40、NCEP-2再分析资料与观测资料的初步比较与分析 总被引：31，自引：6，他引：25
再分析资料在气候变化研究中有着广泛的应用,但是再分析资料在不同时空尺度上的可信度能够影响到研究结果。作者就中国区域的月平均地表(2 m)气温和降水两种基本气候变量在空间分布及其变化趋势上对ERA-40和NCEP-2与观测资料之间的差异做了一些比较和分析,对两套再分析资料的可信度进行了初步的检验。结果表明:两套再分析资料基本上都能反映出中国区域的温度场和降水场的时空分布,尽管在中国西部,尤其是青藏高原地区的差异比较较大;再分析资料在东部地区的可信度高于西部,温度场的可信度要高于降水场,ERA-40可信度要高于NCEP-2。 相似文献
12.
Convective and stratiform precipitation characteristics in an ensemble of regional climate model simulations 总被引：1，自引：0，他引：1
We apply a recently proposed algorithm for disaggregating observed precipitation data into predominantly convective and stratiform, and evaluate biases in characteristics of parameterized convective (subgrid) and stratiform (large-scale) precipitation in an ensemble of 11 RCM simulations for recent climate in Central Europe. All RCMs have a resolution of 25 km and are driven by the ERA-40 reanalysis. We focus on mean annual cycle, proportion of convective precipitation, dependence on altitude, and extremes. The results show that characteristics of total precipitation are often better simulated than are those of convective and stratiform precipitation evaluated separately. While annual cycles of convective and stratiform precipitation are reproduced reasonably well in most RCMs, some of them consistently and substantially overestimate or underestimate the proportion of convective precipitation throughout the year. Intensity of convective precipitation is underestimated in all RCMs. Dependence on altitude is also simulated better for stratiform and total precipitation than for convective precipitation, for which several RCMs produce unrealistic slopes. Extremes are underestimated for convective precipitation while they tend to be slightly overestimated for stratiform precipitation, thus resulting in a relatively good reproduction of extremes in total precipitation amounts. The results suggest that the examined ensemble of RCMs suffers from substantial deficiencies in reproducing precipitation processes and support previous findings that climate models’ errors in precipitation characteristics are mainly related to deficiencies in the representation of convection. 相似文献
13.
C. G. Menéndez M. de Castro J.-P. Boulanger A. D’Onofrio E. Sanchez A. A. Sörensson J. Blazquez A. Elizalde D. Jacob H. Le Treut Z. X. Li M. N. Núñez N. Pessacg S. Pfeiffer M. Rojas A. Rolla P. Samuelsson S. A. Solman C. Teichmann 《Climatic change》2010,98(3-4):379-403
We investigate the performance of one stretched-grid atmospheric global model, five different regional climate models and a statistical downscaling technique in simulating 3 months (January 1971, November 1986, July 1996) characterized by anomalous climate conditions in the southern La Plata Basin. Models were driven by reanalysis (ERA-40). The analysis has emphasized on the simulation of the precipitation over land and has provided a quantification of the biases of and scatter between the different regional simulations. Most but not all dynamical models underpredict precipitation amounts in south eastern South America during the three periods. Results suggest that models have regime dependence, performing better for some conditions than others. The models’ ensemble and the statistical technique succeed in reproducing the overall observed frequency of daily precipitation for all periods. But most models tend to underestimate the frequency of dry days and overestimate the amount of light rainfall days. The number of events with strong or heavy precipitation tends to be under simulated by the models. 相似文献
14.
Dynamical downscaling of ERA-40 in complex terrain using the WRF regional climate model 总被引：4，自引：0，他引：4
Results from a first-time employment of the WRF regional climate model to climatological simulations in Europe are presented. The ERA-40 reanalysis (resolution 1°) has been downscaled to a horizontal resolution of 30 and 10?km for the period of 1961?C1990. This model setup includes the whole North Atlantic in the 30?km domain and spectral nudging is used to keep the large scales consistent with the driving ERA-40 reanalysis. The model results are compared against an extensive observational network of surface variables in complex terrain in Norway. The comparison shows that the WRF model is able to add significant detail to the representation of precipitation and 2-m temperature of the ERA-40 reanalysis. Especially the geographical distribution, wet day frequency and extreme values of precipitation are highly improved due to the better representation of the orography. Refining the resolution from 30 to 10?km further increases the skill of the model, especially in case of precipitation. Our results indicate that the use of 10-km resolution is advantageous for producing regional future climate projections. Use of a large domain and spectral nudging seems to be useful in reproducing the extreme precipitation events due to the better resolved synoptic scale features over the North Atlantic, and also helps to reduce the large regional temperature biases over Norway. This study presents a high-resolution, high-quality climatological data set useful for reference climate impact studies. 相似文献
15.
利用实测资料对NCEP-1、ERA-40和20CR再分析降水资料在中国范围内均值、年际变化、相关性和长期趋势等方面进行比较评估。结果表明,平均而言ERA-40年降水量和实测值最为接近,而20CR和NCEP-1年降水量明显偏多,三者差值百分比分别为-1.3%,55.0%和36.9%;三种再分析降水偏差最大区均出现在西南地区,最大偏差值都在600 mm以上;年际变化上,ERA-40和NCEP-1自20世纪70年代中期开始年降水差值百分比出现一定波动性,而20CR在整个研究时段年降水差值百分比基本稳定;三套资料和实测资料的相关性具有明显的区域性特征,东部相关系数明显高于西部,值得一提的是ERA-40在大部地区的相关性好于其他两套资料;ERA-40和20CR则对大部分区域降水变化趋势的描述好于NCEP-1资料。 相似文献
16.
In this study, we examine a long-term increasing trend in subtropical potential vorticity (PV) intrusion events over the Pacific Ocean in relation to the global mean temperature rise, based on multiple reanalysis datasets. The frequency of the PV intrusions is closely related to the upper-tropospheric equatorial westerly duct and the subtropical jet (STJ). An overall strengthening of the westerly duct and weakening of the STJ are found to be driven by the warming-induced strengthening of Walker circulation and regional changes in Hadley circulation on multi-decadal timescale, leading to an increase in the PV intrusion frequency over the tropics. The results are robust in all datasets. The multi-decadal strengthening in the Pacific Walker circulation is consistent with the global mean temperature rise. In this way, the PV intrusions are correlated with the warming related global mean temperuate rise. When the interannual variability of ENSO is removed from the intrusion time series, the long-term trend in PV intrusions due to external forcing associated with anthropogenic warming (global mean temperature rise) becomes clearer. The link between the global mean temperature rise and intrusion frequency is further verified by performing a correlation analysis between the two. The significant (> 95%) correlation coefficient is 0.85, 0.94, 0.84, 0.83, and 0.84 for ERA-40, ERA-Interim, NCEP-NCAR, JRA-55, and JRA-25, respectively. This unequivocally indicates that the global mean temperature rise can explain around 69%–88% of the variance related to the long-term increase in PV intrusion frequency over the Pacific Ocean. 相似文献
17.
根据NCEP/NCAR、NCEP/DOE、ERA-40和JRA-25共4种比较常用的再分析资料在中国区域的适用性研究作了概述。结果表明：发现4种资料既呈现出一定的共性,又在不同区域、不同时间尺度上差异显著。再分析资料的可信度普遍表现为在东部地区好于西部地区,低纬地区好于高纬地区,这可能与中国地面气象站点“东密西疏”有关;1979年前的再分析资料存在较大的不确定性,因此应用该时段NCEP/NCAR资料研究长期气候变化研究时需要谨慎;再分析资料的不同要素在不同时间、不同地域的适用性不同,因此应分区域、分要素、分季节选择合适的资料。从不同角度研讨了再分析资料的优缺点及在中国区域的适用性,旨在为中国区域气候变化研究选用再分析资料提供借鉴和参考。 相似文献
18.
Hydrological issues in lateral boundary conditions for regional climate modeling: simulation of east asian summer monsoon in 1998 总被引：1，自引：0，他引：1
The atmospheric branch of the hydrological cycle associated with the East Asian summer monsoon is intricate due to its distinct
land-sea configurations: the highest mountains are to its west, the oceans are to its south and east, and mid-latitude influences
come from its north. Here we use the weather research and forecast (WRF) model to demonstrate that using two different large-scale
driving fields, derived from the NCEP/DOE R2 and ERA40 reanalysis data and the same model configuration yielded remarkable
differences. We found that the differences are primarily caused by uncertainties in the water vapor influx across the lateral
boundaries in the reanalyses. The summer-mean water vapor convergence into the model domain computed from the ERA40 reanalysis
is 47% higher than that from the R2 reanalysis. The largest uncertainties in moisture transport are found in the regions of
the Philippine Sea and the Bay of Bengal, where the moisture transport has the most significant impacts on the East Asian
summer monsoon rainfall distribution. The sensitivity test results suggest that the biases in the seasonal mean, seasonal
march of the rain band, and individual rainfall events may be reduced by using an “ensemble” average of R2 and ERA40 as lateral
boundary forcing. While the large-scale forcing field does not conserve water vapor, the WRF simulation conserves water vapor
in the inner model domain. The regional model simulation has corrected the biases in the total amount and the month-to-month
distribution of precipitation in the large-scale driving field. However, RCM’s daily precipitation is poorer than that in
the reanalysis filed. Since the RCM solutions may sensitively depend on the reanalysis forcing, intercomparison of models’
performance based on a single set of the reanalysis may not be reliable. This calls for attention to reshape our strategy
for validation of RCMs. 相似文献
19.
Annual precipitation,evaporation,and calculated accumulation from reanalysis model outputs have been investigated for the Greenland Ice Sheet (GrIS),based on the common period of 1989-2001.The ERA-40 and ERA-interim reanalysis data showed better agreement with observations than do NCEP-1 and NCEP-2 reanalyses.Further,ERA-interim showed the closest spatial distribution of accumulation to the observation.Concerning temporal variations,ERA-interim showed the best correlation with precipitation observations at five synoptic stations,and the best correlation with in situ measurements of accumulation at nine ice core sites.The mean annual precipitation averaged over the whole GrIS from ERA-interim (363 mm yr 1) and mean annual accumulation (319 mm yr 1) are very close to the observations.The validation of accumulation calculated from reanalysis data against ice-core measurements suggests that further improvements to reanalysis models are needed. 相似文献
20.
本文使用六个不同的最新大气模式进行了协调数值集合实验,评估和量化了全球海表面温度(SST)对1982-2014年冬季早期北极变暖的影响.本研究设计了两组实验:在第一组(EXP1)中,将OISSTv2逐日变化的海冰密集度和SST数据作为下边界强迫场;在第二组(EXP2)中,将逐日变化的SST数据替换为逐日气候态.结果表明... 相似文献