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1.
集合均方根滤波同化地面自动站资料的技术研究 总被引：3，自引：1，他引：2
模式地形与观测站地形高度差异一直是地面资料同化面临的棘手问题,合理的同化方案能够将地面自动站资料有效的同化到中尺度数值模式中。本文首先采用Guo et al.(2002)的方案实现了在WRF模式中应用集合Kalman滤波方法同化地面自动站资料;然后对方案进行调整,对10 m高度风场、2 m高度位温、2 m高度露点和地表气压进行同化。通过均方根误差分析,模拟结果和同化增量分析来确定集合平方根滤波(EnSRF)同化地面自动站资料的有效性,并进行敏感性试验分析检验模式对各要素物理量的响应状况。结果表明:在EnSRF同化系统中应用Guo et al.(2002)的方案将地面自动站资料进行同化到数值模式中,能够部分改善模拟结果;地面观测资料(温度、湿度、风场、地表气压)中各物理量分别同化到数值模式都能影响18小时降水预报,但各物理量所起作用大小不同,其中对结果影响最大的是露点;使用位温、露点分别代替温度、比湿进行同化模拟效果更好,对自动站资料的同化也更加有效。 相似文献
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对中国国家气象中心T639数值预报、德国降水预报和欧洲中心（ECMWF）数值预报中对中国东北地区的降水、温度和环流模式的预报结果，分别进行检验。结果表明：降水预报中，德国降水预报对中国东北地区的晴雨预报、一般性降水预报效果较好，但T639数值预报的漏报率明显低于德国降水预报，而T639数值预报中24-120 h暴雨预报的TS评分明显高于德国降水预报。温度预报中，T639数值预报对中国东北地区温度预报72 h内基本可用；欧洲中心（ECMWF）数值预报在96 h内效果较好。对于24 h的温度预报准确率，T639数值预报稍高于ECMWF数值预报结果。环流模式方面：48h内T639预报效果好于ECMWF，72 h以后ECMWF预报效果好于T639。 相似文献
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本文基于区域暴雨数值预报模式AREM，对2008年7月四川地区的整月天气过程进行数值模拟试验，分别采用台站常规报文资料、3213预报场资料和以T213资料为背景场，融合常规报文资料3种初值，发现得到的模拟结果差异很大，其中以台站常规资料为初值模拟的降水最接近实况。和台站资料相比，T213预报场资料在四川盆地中西部中低层大气的湿度偏大，温度偏高，风场偏强，而位势高度偏低，直接导致了模拟的降水偏强。这些初值的差异随着积分时间逐渐变小，通过对比逐时降水发生发展过程，发现降水的差异与湿度的调整最为吻合，初值中各个量场对模拟结果都有一定的影响，其中水汽场的影响最为显著，位势高度场的影响最弱。通过比较不同时次初值的模拟结果还发现，0000UTC时刻大气系统相对稳定，故以此为初值模拟的降水比从1200UTC时刻开始模拟的降水更合理。模式模拟的前24h降水比后24h降水的效果更好，一方面说明临近预报的准确度更可靠，另一方面也反映积分前期模式对初值的响应相当敏感。 相似文献
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初始场条件直接影响到区域模式的预报性能。基于GRAPES_GFS和NCEP_GFS两种初始场，详细比较了两者之间的差异，随后分别利用两种初始场驱动新疆区域数值模式（RMAPS-CA V1.0），对2021年4月整月的数值预报结果以及2021年4月21日一次暴雨过程模拟结果进行了MET（Model Evaluation Tools）对比检验。结果表明：（1）两种资料位势高度扰动场、温度扰动场、湿度扰动场存在明显差异，其相关系数分别为0.26~0.60、0.05~0.24和0.01~0.12，导致次天气尺度上存在着较大差异，并由此造成了模拟结果之间的差异，反映了区域模式对初始场和边界条件的敏感性；（2）从高空位势高度、风速、温度的预报结果看，NCEP_GFS初始场在新疆区域模式中高空要素的预报效果均要优于GRAPES_GFS初始场，均方根误差分别降低35.5~37.2%、7.6~12.6%和6.0~17.2%。从地面常规预报量的检验看，GRAPE_GFS初始场对2 m温度和10 m风速的预报效果则要优于NCEP_GFS初始场，均方根误差分别降低14.3%和6.8%；（3）从降水检验评分看，两种初始场的降水预报整体为漏报现象，NCEP_GFS初始场针对各降水阈值及不同时效的预报降水评分要高于GRAPES_GFS，0.1 mm/6h、6.1 mm/6h和12.1 mm/6h的TS评分分别提高22.5%、16.1%和150.8%；（4）从一次暴雨过程预报的检验结果看，GRAPES_GFS对于24小时为小量级降水预报效果优于NCEP_GFS,准确率分别为61.4%和40.0%；而NCEP_GFS对于大量级的降水预报则要优于GRAPES_GFS,准确率分别为66.7%和33.3%。两种初始场对降水个例检验偏差以空报现象为主，NCEP_GFS的TS评分整体高于GRAPES_GFS。 相似文献
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数值预报系统检验结果对预报产品的释用和系统的改进有着重要的作用。基于MET（Model Evaluation Tools）检验工具对乌鲁木齐区域高分辨率数值预报系统V2.0 (Rapid-refresh Multi-scale Analysis and Prediction System—Central Asia V2.0，简称RMAPS-CA V2.0）在2021年各季节中的预报性能进行客观检验评估，主要检验了2m温度、10m风速、高空位势高度等要素，并与RMAPS-CA V1.0同期预报性能进行对比分析。（1）2m温度预报偏差在冬季和春季整体为负偏差，在夏季和秋季整体为正偏差；各个季节的平均预报偏差均在2℃以内，预报性能秋季最优，冬季最差。各个季节10m风速预报整体为正偏差且差异不大，平均误差在0.5-1.0 m/s之间，预报性能秋季最优，春季最差。（2）高空位势高度预报偏差在冬季整体为负偏差，在其余季节整体为正偏差，预报性能冬季最优，春季最差。高空风场预报偏差在冬季和春季400hPa以下为正偏差，400hPa以上为负偏差；夏季和秋季整体为负偏差，预报性能春季最优、夏季最差。高空温度场预报偏差在冬季整体为负偏差，其余季节整体为正偏差，预报性能春季最优、夏季最差。（3）降水晴雨预报效果较好，但除夏季外以空报为主；随降水阈值增大、TS评分减小，多以漏报为主，降水评分在冬季最高、夏季最低。从降水个例检验看，24h累计降水为大量和中量的国家站点预报性能有所提升，逐6h累计降水TS评分略有提升。（4）RMAPS-CA V2.0系统各要素预报偏差的变化特征与RMAPS-CA V1.0相似，预报能力整体上要优于RMAPS-CA V1.0。 相似文献
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使用GRAPES中尺度模式对中国新疆南部的塔里木盆地2013年1、4、7、10月逐日的天气过程进行数值模拟,并与站点的实况资料对比分析,结果表明,GRAPES模式对沙漠地区的温度、风场、降水都有一定的预报能力,但也存在较明显的预报误差。GRAPES模式可以大致的预报出塔里木盆地地区2 m温度的日变化趋势,但GRAPES模拟的温度极值还存在较明显的误差;GRAPES模式对10m风场的预报,在风速较大的1月、4月和10月预报效果较好,基本可以预测出沙漠地区的风速和风向,但在风速很小的7月,模式的预报效果不理想;GRAPES模式对沙漠地区的降水预报与实况相比还存在明显的偏差,主要表现为降水空报率较高,降水中心也存在一定的偏差;GRAPES模式在沙漠地区对高空温度的预报呈现出低层温度预报误差较大,高空相对较小的特征。 相似文献
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为了更加有效地同化地面自动气象站观测资料,针对模式地形与观测站地形存在的高度差异对同化效果的影响,提出了相应的解决方案。在同化系统的位温和露点观测误差中分别引入位温和露点地形代表性误差,在WRF模式中应用集合均方根滤波方法（EnSRF）同化地面自动气象站观测资料,并对2016年一次京津冀暴雨个例进行数值试验。研究结果表明,同化地面资料后,同化阶段的均方根误差、预报阶段的降水TS评分和前13个时次各要素预报均有整体改进。在观测误差中引入地形代表性误差与引入前相比,风场均方根误差得到整体改进;位温和露点的均方根误差在前期表现并不稳定,在后期有所改进;预报阶段前24 h累计降水与后24 h累计降水TS评分在整体上均有所提高。新方案能够减少高度差异对同化效果的影响。 相似文献
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周智翔 《热带气象学报(英文版)》2009,15(1):1-12
On the basis of a comprehensive literature review and data analysis of global influenza surveillance, a transmission theory based numerical model is developed to understand the causative factors of influenza seasonality and the biodynamical mechanisms of seasonal flu. The model is applied to simulate the seasonality and weekly activity of influenza in different areas across all continents and climate zones around the world. Model solution and the good matches between model output and actual influenza indexes affirm that influenza activity is highly auto-correlative and relies on determinants of a broad spectrum. Internal dynamic resonance; variations of meteorological elements (solar radiation, precipitation and dewpoint); socio-behavioral influences and herd immunity to circulating strains prove to be the critical explanatory factors of the seasonality and weekly activity of influenza. In all climate regions, influenza activity is proportional to the exponential of the number of days with precipitation and to the negative exponential of quarter power of sunny hours. Influenza activity is a negative exponential function of dewpoint in temperate and arctic regions and an exponential function of the absolute deviation of dewpoint from its annual mean in the tropics. Epidemics of seasonal influenza could be deemed as the consequence of the dynamic resonance and interactions of determinants. Early interventions (such as opportune vaccination, prompt social distancing, and maintaining incidence well below a baseline) are key to the control and prevention of seasonal influenza. Moderate amount of sunlight exposure or Vitamin D supplementation during rainy and short-day photoperiod seasons, more outdoor activities, and appropriate indoor dewpoint deserve great attention in influenza prevention. To a considerable degree, the study reveals the mechanism of influenza seasonality, demonstrating a potential for influenza activity projection. The concept and algorithm can be explored for further applications. 相似文献
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Precession-related forcing of seasonal insolation changes in the northern hemisphere (NH) alternates between maximum NH seasonality (summer perihelion–increased insolation; winter aphelion–decreased insolation) and minimum NH seasonality (summer aphelion, and winter perihelion). With maximum NH seasonality, climate models simulate stronger NH summer monsoons that bring increased precipitation to North Africa and South and East Asia, in agreement with the in-phase relation of precipitation and NH summer insolation found in many paleoclimatic records. However paleoclimatic records in parts of the Mediterranean, the Middle East, and the interior of Asia also indicate increased moisture at times of maximum NH seasonality, a change not always clearly linked to stronger summer monsoons—either because these regions are at or beyond the boundaries of the present-day monsoon or because the observations allow multiple causal interpretations, or both. This study focuses on the possible role of changes in NH winter climate in explaining these wetter episodes. Using climate model simulations, we show that the ‘NH winter aphelion–decreased NH winter insolation’ orbital configuration is linked to the Mediterranean storm track and increased winter rains in the Mediterranean, the Middle East, and interior Asia. We conclude that wetter periods at precession time scales in these particular regions may have resulted either from increased wintertime storm track precipitation, or from a combination of increased winter and summer rainfall. Given this seasonal ambiguity, both possibilities need to be considered. 相似文献
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Very extreme seasonal precipitation in the NARCCAP ensemble: model performance and projections 总被引：1，自引：1，他引：0
Michael F. Wehner 《Climate Dynamics》2013,40(1-2):59-80
Seasonal extreme daily precipitation is analyzed in the ensemble of NARCAPP regional climate models. Significant variation in these models’ abilities to reproduce observed precipitation extremes over the contiguous United States is found. Model performance metrics are introduced to characterize overall biases, seasonality, spatial extent and the shape of the precipitation distribution. Comparison of the models to gridded observations that include an elevation correction is found to be better than to gridded observations without this correction. A complicated model weighting scheme based on model performance in simulating observations is found to cause significant improvements in ensemble mean skill only if some of the models are poorly performing outliers. The effect of lateral boundary conditions are explored by comparing the integrations driven by reanalysis to those driven by global climate models. Projected mid-century future changes in seasonal precipitation means and extremes are presented and discussions of the sources of uncertainty and the mechanisms causing these changes are presented. 相似文献
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Meng Sei Kwan Fredolin T. Tangang Liew Juneng 《Theoretical and Applied Climatology》2014,115(1-2):1-14
This study examines the performance of the regional climate model, PRECIS, in reproducing the historical seasonal mean climatology over the Malaysian region. The performance of the model in simulating the seasonal climate pattern of the temperature, precipitation and large-scale circulation was reasonably good. The biases of temperature are less than 2 °C in general, while the seasonal cycles match the observed pattern despite some differences in certain regions. However, the biases for precipitation were greater, particularly over the mountainous areas. These biases could be associated with the deficiencies of the model physics, related to the misrepresentation of the land–surface interaction and convective scheme. Furthermore, the model fails to simulate the mean sea-level pressure over the interior part of Borneo with a significant low-pressure centre. A higher magnitude of the moisture convergence and divergence simulated by the model also contributed to the biases of precipitation over Malaysia. 相似文献
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基于6个CMIP6模式的日降水量数据,采用降尺度方法将其统一分辨率到0.25°×0.25°,选取5个极端降水指数从降水气候态、极端性、季节性三个角度对新疆区域1961—2014年历史期降水模拟效果评估。结果表明,降尺度CMIP6模式能较好再现新疆区域降水的空间分布特征,最大年均降水量误差小于30 mm,夏季降水模拟效果最佳相关系数均高于0.8。模式在春秋季对降水的模拟效果差异较小,标准差比值均在1.00 ~ 1.25之间,ACCESS-CM2模拟效果最佳。模式集合均值能模拟出观测降水增多趋势,但低估了降水的年际变率,模拟结果提示新疆80年代的降水转折可能与人类活动有关。在降水极端性和季节性方面,降尺度数据对新疆的极端降水和季节性降水均有较好的模拟性能,降尺度数据对季节性降水的模拟能力（与观测均值误差小于0.001）比原始分辨率的数据（与观测误差大于0.005）效果更好。 相似文献
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中国降水的季节性 总被引：1，自引：0，他引：1
本文使用一套基于中国气象局所属的2416个台站数据所得的高分辨降水资料,对1961~2013年中国降水季节性进行了研究。就全国平均而言,各季节降水占全年降水百分率最高的为夏季（56.5%）,春季（19.3%）和秋季（18.9%）次之,冬季（5.3%）最少;针对不同地区,各季节降水百分率存在很大差异,例如华南春季降水最多、东北至高原一线秋季降水大于春季降水。春、夏两季降水百分率高值（低值）区域略呈现出降水百分率减少（增多）趋势,秋季整体上略微减少,冬季则显著增加;季节降水百分率的变率整体表现为夏季大而冬季小,其西部的变率与地形为显著负相关,东部变率的大值区位置随季节变化;秋冬两季的降水百分率变率有显著增加,各季节不同地区变率的变化趋势存在明显差异。 相似文献
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We present an analysis of a regional simulation of present-day climate (1981–1990) over southern South America. The regional
model MM5 was nested within time-slice global atmospheric model experiments conducted by the HadAM3H model. We evaluate the
capability of the model in simulating the observed climate with emphasis on low-level circulation patterns and surface variables,
such as precipitation and surface air mean, maximum and minimum temperatures. The regional model performance was evaluated
in terms of seasonal means, seasonal cycles, interannual variability and extreme events. Overall, the regional model is able
to capture the main features of the observed mean surface climate over South America, its seasonal evolution and the regional
detail due to topographic forcing. The observed regional patterns of surface air temperatures (mean, maxima and minima) are
well reproduced. Biases are mostly within 3°C, temperature being overestimated over central Argentina and underestimated in
mountainous regions during all seasons. Biases in northeastern Argentina and southeastern Brazil are positive during austral
spring season and negative in other seasons. In general, maximum temperatures are better represented than minimum temperatures.
Warm bias is larger during austral summer for maximum temperature and during austral winter for minimum temperature, mainly
over central Argentina. The broad spatial pattern of precipitation and its seasonal evolution are well captured; however,
the regional model overestimates the precipitation over the Andes region in all seasons and in southern Brazil during summer.
Precipitation amounts are underestimated over the La Plata basin from fall to spring. Extremes of precipitation are better
reproduced by the regional model compared with the driving model. Interannual variability is well reproduced too, but strongly
regulated by boundary conditions, particularly during summer months. Overall, taking into account the quality of the simulation,
we can conclude that the regional model is capable in reproducing the main regional patterns and seasonal cycle of surface
variables. The present reference simulation constitutes the basis to examine the climate change simulations resulting from
the A2 and B2 forcing scenarios which are being reported in a separate study. 相似文献
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基于旋转经验正交函数分解 (REOF) 方法探讨淮河流域1961—2010年夏季降水与厄尔尼诺/南方涛动 (ENSO)、北大西洋涛动 (NAO)、印度洋偶极子 (IOD)、太平洋年代际振荡 (PDO) 之间的关系,并进一步分析各气候因子不同位相单独以及联合对淮河流域夏季降水的影响。结果表明:淮河流域夏季降水与ENSO,PDO,NAO,IOD等气候因子具有较稳定的相关性,其中,PDO和IOD是影响淮河流域夏季降水的关键因子,且PDO与夏季降水呈显著负相关关系;各气候因子的冷暖位相单独及联合对淮河流域夏季降水的影响不同,PDO的冷期以及NAO,IOD冷位相使流域北部的夏季降水量呈显著增加趋势,PDO分别联合ENSO,NAO和IOD的冷、暖位相对流域北部地区和淮河上游地区的夏季降水影响显著。 相似文献
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Indices for temperature and precipitation extremes are calculated on the basis of the global climate model ECHAM5/MPI-OM simulations
of the twentieth century and SRES A1B and B1 emission scenarios for the twenty-first century. For model evaluation, the simulated
indices representing the present climate were compared with indices based on observational data. This comparison shows that
the model is able to realistically capture the observed climatological large-scale patterns of temperature and precipitation
indices, although the quality of the simulations depends on the index and region under consideration. In the climate projections
for the twenty-first century, all considered temperature-based indices, minimum Tmin, maximum Tmax, and the frequency of tropical
nights, show a significant increase worldwide. Similarly, extreme precipitation, as represented by the maximum 5-day precipitation
and the 95th percentile of precipitation, is projected to increase significantly in most regions of the world, especially
in those that are relatively wet already under present climate conditions. Analogously, dry spells increase particularly in
those regions that are characterized by dry conditions in present-day climate. Future changes in the indices exhibit distinct
regional and seasonal patterns as identified exemplarily in three European regions. 相似文献
20.
p—σRCM模式对中国区域气候季节变化的模拟 总被引：4，自引：0，他引：4
通过对区域气候季节变化的模拟，对p-σ坐标系区域气候模式的模拟能力进行了检验，模式较准确地再现了中国区域气候系统的季节性变化特征及中国东部降水带的季节性进退，模拟的各气候区域水的季节变化趋势也与实况基本相符，但模式低估了华东和华南地区的春季降水，而高估了华东，西南和西北地区的秋季降水。 相似文献