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1.
区域四维变分资料同化的数值试验 总被引:14,自引:0,他引:14
针对中尺度数值预报模式预报误差的主要来源,尝试利用四维变分资料同化的方法来改善预报效果。在已建立的中尺度模式(MM4)四维变分资料同化系统基础上,进行了若干数值试验,通过比较同化前后的预报来检验同化的效果。这些试验中初始场、模式误差和侧边界条件被分别或同时作为控制变量来进行调整,主要探讨了模式误差和侧边界条件对同化及预报的影响,以及同时结合两者或三者的途径和方法。对两组个例分别进行的试验结果表明,区域中尺度模式预报误差除了来源于初始误差外,模式误差、侧边界条件也有不可忽视的作用。同化时应同时考虑初始场、模式误差和侧边界条件这三方面的共同作用,仅修正其中某一个或某两个会把由于其它方面造成的预报误差转嫁到它们之上,从而出现尽管目标函数下降很快而预报结果并没有相应改善的现象。 相似文献
2.
在传统的基于角色访问权限管理 (RBAC) 模型基础上结合气象数据自身特点及共享服务中的权限控制需求,提出了一种符合气象资料管理特点的多维度权限管理模型。该模型充分考虑了气象数据进行资源共享时资料分类众多、层次化结构复杂、检索粒度不同等特点,有针对性引入了客体维度概念和更灵活的权限管理机制,较好地满足了气象部门数据共享服务系统建设的需求。该方案作为全国综合气象信息共享平台 (CIMISS) 数据服务权限控制模型的前期试验研究,构建一个多维数据权限管理原型系统用于数据访问控制。作为通用性模型,该模型可以延伸用于气象数据服务类系统应用,对确保数据库的信息安全、防止用户越权访问数据、保障管理信息系统的正常运行具有重要意义。 相似文献
3.
为保障北京气候中心(Beijing Climate Center,BCC)气候模式在第6次耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中的大量试验数据产品面向国内外实现共享,建立了试验数据共享平台。由于模式试验数据具有数据量大、要素种类繁多、元数据多样等特征,为提供高效的数据管理,平台采用分布式存储架构,数据通过气候模式输出重写(climate model output rewriter,CMOR)软件进行格式规范,并实现基于THREDDS(thematic real-time environmental distributed data services)的数据组织与共享。在平台建设及软件设计部署等层面,充分考虑数据安全。该平台实现BCC 3个模式约190 TB的试验数据稳定、高效共享,为国内外气候变化领域科研工作者提供获取数据的方便快捷途径与方法,成为推动我国气候模式国际应用的有力技术手段。 相似文献
4.
利用卷积神经网络和门控循环单元(Gated recurrent units )神经网络,基于雷达反射率因子和雷电定位数据开展了雷电预报研究。首先构建了引用注意力机制的基于卷积神经网络和门控循环单元神经网络的深度学习模型(Attention ConvGRU);然后将雷达反射率因子数据和对应时间段(6 min)的雷电定位数据处理成图像数据后输入深度学习模型,训练出可预报雷电的模型,包括3种模型:单雷电数据模型、单雷达数据模型和雷电〖CD*2〗雷达双数据模型;最后开展了预报试验和定量评估。综合评估表明,本文建立的雷电预报模型综合预报准确率达到96.74%,虚警率35.83%,关键成功指数(Critical Success Index, CSI)为0.2072。个例分析表明,预报模型对于具有明显移动趋势的雷暴过程(A类雷暴)的预报效果优于不具有明显移动趋势的雷暴过程(B类雷暴),且随着B类雷暴强度减弱模型预报能力逐渐减弱。 相似文献
5.
用支持向量机(SVM)方法根据T213数值资料和济南、淄博、泰安、莱芜4站的降水实况资料对山东山洪灾害多发的鲁中山区进行了降水分类预报试验。结果表明:多项式核和径向基核函数建立的模型较好地提炼了降水信息,都具有很高的预报技巧,客观性和实用性强,有很强的推广能力;用径向基核函数建的非线性降水分类模型优于用多项式核函数建立的线性降水分类预报,特别是资料减少时,非线性降水分类预报明显优于线性降水分类预报;低层大气湿度可能对线性降水分类有重要影响;建模时用的资料数据格式与实际业务中获得的数据格式应尽量保持一致。 相似文献
6.
本文利用1970至1989年共20年的逐月平均的太平着区的表面风应力和海表温度距平的分析资料,检验了以前设计的热带太平洋和热带大气距平模式的模拟性能,通过使用两组风应力异常场即观测场和热带大气模式对观测海温响应所得的模拟场,重点分析了热带太平洋距平模式对风应力异常的响应特征,结果表明,本文海洋距平模式完全有能力再现ENSO循环折际变化性及其水平结构,且赤道中太平洋区域的低频风应力异常对于ENSO事 相似文献
7.
本文采用Lorenz(1960)系统,在只考虑初始误差及观测误差而不考虑模式误差的情况下,利用扩展卡尔曼滤波(Extended Kalman Filter)数据同化方法进行了数值模拟试验。数值试验的结果表明:扩展卡尔曼滤波数据同化方法对系统状态的估计有较好的改善作用,能有效的抑制估计误差的增长;加大观测频率,可以进一步改善数据同化的效果,使估计误差进一步减小;由于模式误差的存在,系统的不稳定能量会不断的累积,出现了估计误差的异常增长和计算的不连续现象,在模式预报方程中的均值演变方程加人二阶偏差纠错项,对控制估计误差的异常增长,进一步改善数据同化的效果有较明显作用。 相似文献
8.
This paper is adapted from a presentation at the session of the European Geophysical Society meeting in 2002 honouring Joost
Businger. It documents the interaction of the non-linear planetary boundary-layer (PBL) model (UW-PBL) and satellite remote
sensing of marine surface winds from verification and calibration studies for the sensor model function to the current state
of verification of the model by satellite data. It is also a personal history where Joost Businger had seminal input to this
research at several critical junctures. The first scatterometer in space was on SeaSat in 1978, while currently in orbit there
are the QuikSCAT and ERS-2 scatterometers and the WindSat radiometer. The volume and detail of data from the scatterometers
during the past decade are unprecedented, though the value of these data depends on a careful interpretation of the PBL dynamics.
The model functions (algorithms) that relate surface wind to sensor signal have evolved from straight empirical correlation
with simple surface-layer 10-m winds to satellite sensor model functions for surface pressure fields. A surface stress model
function is also available. The validation data for the satellite model functions depended crucially on the PBL solution.
The non-linear solution for the flow of fluid in the boundary layer of a rotating coordinate system was completed in 1969.
The implications for traditional ways of measuring and modelling the PBL were huge and continue to this day. Unfortunately,
this solution replaced an elegant one by Ekman with a stability/finite perturbation equilibrium solution. Consequently, there
has been great reluctance to accept this solution. The verification of model predictions has been obtained from the satellite
data. 相似文献
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10.
中尺度数值模式MM5的四维变分资料同化系统 总被引:6,自引:5,他引:6
应用伴随方法求解以数值预报方程作为约束条件的四维变分资料同化方案,关键问题是如何构造伴随模式。以中尺度数值模式MM5为例,讨论了如何用伴随码技术建立MM5伴随模式,以及伴随模式系统中权重、尺度因子的选取;最后对MM5伴随模式系统进行了梯度检验,并利用实际资料进行四维变分资料同化试验。试验表明该系统有较强的同化能力,能够提高MM5降水预报的准确性。 相似文献
11.
陕西渭北东部干旱遥感监测模型研究 总被引:5,自引:2,他引:5
利用研究区域2001年NOAA-16卫星遥感资料和有关气象资料,根据作物生长发育季节,使用逐步回归的统计方法进行因子筛选,用选出的因子建立研究区域不同季节干旱遥感监测模型。用建立的模型对2002年该区春季干旱进行监测,结果表明:模型土壤湿度监测结果与地面观测结果较为一致,模型对该区干旱具有较好的监测能力。 相似文献
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13.
国家气象中心数值预报业务的进展 总被引:1,自引:0,他引:1
在最近的15年中,国家气象中心的数值预报业务高速度发展,预报模式从北半球模式发展为全球谱模式,并配套建立了资料同化系统和用于降水预报的有限区预报模式,暴雨和台风预报模式正在研制中。目前数值预报时效已延至7天,T6393丙上时的预报水平已优于的数值预报产品的应用技术在不断改进,最高(低)气温下两天MOS预报精度已接近预报员制作的综合预报结果。 相似文献
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15.
The growing interest in and emphasis on high spatial resolution estimates of future climate has demonstrated the need to apply
regional climate models (RCMs) to that problem. As a consequence, the need for validation of these models, an assessment of
how well an RCM reproduces a known climate, has also grown. Validation is often performed by comparing RCM output to gridded
climate datasets and/or station data. The primary disadvantage of using gridded climate datasets is that the spatial resolution
is almost always different and generally coarser than climate model output. We have used a Bayesian statistical model derived
from observational data to validate RCM output. We used surface air temperature (SAT) data from 109 observational stations
in California, all with records of approximately 50 years in length, and created a statistical model based on this data. The
statistical model takes into account the elevation of the station, distance from coastline, and the NOAA climate region in
which the station resides. Analysis indicates that the statistical model provides reliable estimates of the mean monthly SAT
at any given station. In our method, the uncertainty in the estimates produced by the statistical model are directly determined
by obtaining probability density functions for predicted SATs. This statistical model is then used to estimate average SATs
corresponding to each of the climate model grid cells. These estimates are compared to the output of the RCM to assess how
well the RCM matches the observed climate as defined by the statistical model. Overall, the match between the RCM output and
the statistical model is good, with some deficiencies likely due in part to the representation of topography in the RCM. 相似文献
16.
以1990~1999年的42个探空站的3层高度资料为依据,采用文献[1]提出的“滑动展开模型”客观预报技术,建立了以高度场展开系数为因子的龙海县6月暴雨概念化客观预报模型,其历史回报率达56%。在2000~2005年的验证中,客观预报准确率比主观经验预报高10%,且漏报次数(2次)少于主观经验漏报次数(4次)。 相似文献
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18.
南京地区稻田蒸散的研究 总被引:1,自引:1,他引:1
引进半经验模式计算稻田蒸散,仅需要常规气象资料和作物的叶面积资料即可较精确地估算农田蒸散,解决了用Penman-Monteith方法计算误差偏高以及需要风速梯度观测等在实际应用中存在的困难。通过对模式进行参数的敏感性分析,证实了模式的可靠性和可行性。分析稻田蒸散发现水稻一生有两个耗水高峰:拔节期和抽穗开花期,此时的气象条件最有利于水稻蒸散的进行。 相似文献
19.
Summary The existing methods based on statistical techniques for long range forecasts of Indian monsoon rainfall have shown reasonably
accurate performance, for last 11 years. Because of the limitation of such statistical techniques, new techniques may have
to be tried to obtain better results. In this paper, we discuss the results of an artificial neural network model by combining
two different neural networks, one explaining assumed deterministic dynamics within the time series of Indian monsoon rainfall
(Model I) and other using eight regional and global predictors (Model II). The model I has been developed by using the data
of past 50 years (1901–50) and the data for recent period (1951–97) has been used for verification. The model II has been
developed by using the 30 year (1958–87) data and the verification of this model has been carried out using the independent
data of 10 year period (1988–97). In model II, instead of using eight parameters directly as inputs, we have carried out Principal
Component Analysis (PCA) of the eight parameters with 30 years of data, 1958–87, and the first five principal components are
included as input parameters. By combining model I and model II, a hybrid principal component neural network model (Model
III) has been developed by using 30 year (1958–87) data as training period and recent 10 year period (1988–97) as verification
period. Performance of the hybrid model (Model III) has been found the best among all three models developed. Rootmean square
error (RMSE) of this hybrid model during the independent period (1988–97) is 4.93% as against 6.83%of the operational forecasts
of the India Meteorological Department (IMD) using the 16 parameter Power Regression model. As this hybrid model is showing
good results, it is now used by the IMD for experimental long-range forecasts of summer monsoon rainfall over India as a whole.
Received August 20, 1998/Revised April 20, 1999 相似文献