基于AMSR-E土壤湿度产品的LIS同化试验   总被引：2，自引：0，他引：2       下载免费PDF全文

杨晓峰  陆其峰  杨忠东 《应用气象学报》2013,24(4):435-445

由陆面信息系统 (Land Information System, 简称LIS) 通过NOAH陆面过程模型使用集合卡尔曼滤波开展AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System) 土壤湿度同化试验,得到2003年中国区域垂直深度为4层、水平空间分辨率为0.25°×0.25°的土壤湿度试验数据。使用农业气象观测站土壤相对湿度和国家生态系统野外科学观测研究站土壤体积含水量对试验结果进行检验,结果表明:同化过程整体上提高了陆面模型的模拟精度,草地生态系统模拟精度高于作物和森林生态系统;有效的同化过程依赖于AMSR-E土壤湿度的准确性;模拟出的土壤湿度空间分布特征与实际相符。同化试验得到的时空相对连续且精度相对准确的土壤湿度数据是气候变化和干旱监测的重要数据基础。  相似文献   

Impacts of Multigrid NLS-4DVar-based Doppler Radar Observation Assimilation on Numerical Simulations of Landfalling Typhoon Haikui (2012)     

Lu ZHANG  Xiangjun TIAN  Hongqin ZHANG  Feng CHEN 《大气科学进展》2020,37(8):873-892

We applied the multigrid nonlinear least-squares four-dimensional variational assimilation(MG-NLS4DVar) method in data assimilation and prediction experiments for Typhoon Haikui(2012) using the Weather Research and Forecasting(WRF) model. Observation data included radial velocity(V_r) and reflectivity(Z) data from a single Doppler radar, quality controlled prior to assimilation. Typhoon prediction results were evaluated and compared between the NLS-4DVar and MG-NLS4DVar methods. Compared with a forecast that began with NCEP analysis data, our radar data assimilation results were clearly improved in terms of structure, intensity, track, and precipitation prediction for Typhoon Haikui(2012). The results showed that the assimilation accuracy of the NLS-4DVar method was similar to that of the MG-NLS4DVar method,but that the latter was more efficient. The assimilation of V_r alone and Z alone each improved predictions of typhoon intensity, track, and precipitation; however, the impacts of V_r data were significantly greater that those of Z data.Assimilation window-length sensitivity experiments showed that a 6-h assimilation window with 30-min assimilation intervals produced slightly better results than either a 3-h assimilation window with 15-min assimilation intervals or a 1-h assimilation window with 6-min assimilation intervals.  相似文献   

雷达资料同化对一次浙江初春罕见飑线过程数值模拟的影响分析     

陈锋  董美莹  苏涛  冀春晓 《气象》2020,46(4):462-477

以2018年3月4日影响浙江的初春罕见飑线过程为例,利用WRF模式与GSI-3DVar同化系统开展了雷达资料同化对重大强对流天气的影响研究,分析了雷达资料同化对此次飑线过程的模拟改进作用和可能影响过程,对比了雷达反射率因子和雷达径向速度的同化效果,探讨了不同数量和位置的雷达资料同化对模拟效果的影响。结果表明:雷达资料(尤其是反射率因子)同化有效改善了飑线边界层特征的模拟,从而改进了模式对飑线过程中组合反射率因子、降水、大风等发展演变的模拟效果。雷达反射率因子同化通过直接调整水凝物质含量,修正风暴中降水模拟及由此引起的蒸发冷却,形成更接近实况的强冷池,进而产生了比雷达径向速度同化更大的正贡献。相对于同化非关键区域的雷达资料,同化飑线过程上游关键区域的雷达观测所包含的重要中小尺度信息,对飑线过程模拟效果提升更为重要。  相似文献   

Characteristics of Fengyun-4A Satellite Atmospheric Motion Vectors and Their Impacts on Data Assimilation     

Yaodeng CHEN  Jie SHEN  Shuiyong FAN  Deming MENG  Cheng WANG 《大气科学进展》2020,37(11):1222-1238

The high observation efficiency, scanning speed and observation frequency of the Fengyun-4A (FY-4A) satellite indicates the progress of Chinese geostationary meteorological satellites. The characteristics of FY-4A atmospheric motion vectors (AMVs) derived from the high-level water vapor (WV-High) channel, mid-level water vapor (WV-Mid) channel, and infrared (IR) channel of FY-4A are analyzed, and their corresponding observation errors estimated. Then, the impacts of single-channel and multi-channel FY-4A AMVs on RMAPS-ST (the Rapid-refresh Multi-scale Analysis and Prediction System—Short Term) are evaluated based on one-month data assimilation cycling and forecasting experiments. Results show that the observation errors of FY-4A AMVs from the three channels have an explicit vertical structure. Results from the cycling experiments indicate that the assimilation of AMVs from WV-High produces more apparent improvement of the wind in the upper layer, while a more positive effect in the lower layer is achieved by the assimilation of AMVs from IR. Furthermore, the assimilation of AMVs from IR is more skillful for medium and moderate precipitation than from other channels owing to the good quality of data in the lower layer in the AMVs from IR. Assimilation of FY-4A AMVs from the three channels could combine the advantages of assimilation from each individual channel to improve the wind in the upper, middle and lower layers simultaneously.  相似文献   

GRAPES区域扰动预报模式动力框架设计及检验     

冯业荣  薛纪善  陈德辉  吴凯昕 《气象学报》2020,78(5):805-815

设计了适用于四维变分同化系统的扰动预报模式GRAPES_PF。根据GRAPES的地形追随坐标非静力原始方程组,采用小扰动分离方法推导微分形式的线性扰动预报方程组,并利用与GRAPES非线性模式相似的数值求解方案求解线性扰动微分方程组。在设计扰动预报模式时采用了两个时间层半隐式半拉格朗日方案对动量方程、热力学方程、水汽方程和连续方程进行时间差分,空间差分方案的变量分布水平方向采用Arakawa C跳点网格,垂直方向采用Charney/Phillips跳层。利用代数消元法进一步推导得到只包含未来时刻扰动Exner气压的亥姆霍兹方程,进而通过广义共轭余差法（GCR）求解,在此基础上得到未来时刻扰动量的预报值。基于所开发的扰动模式开展了数值试验。首先在非线性模式中施加一个中尺度初始扰动高压,得到初始扰动在非线性模式中的后续演变,然后将相同的初始扰动作为扰动模式的初值进行时间积分,将扰动模式预报的结果与非线性模式的结果做了对比。结果表明,所开发的扰动模式GRAPES_PF较好地模拟了惯性重力内波的传播过程:初始高压扰动激发了一个迅速向外传播的惯性重力内波,在气压场向风场适应的过程中,水平风场、垂直运动、位温和湿度等变量均出现了扰动增量,与非线性模式得到的结果相当接近。GRAPES_PF作为GRAPES非线性模式的合理线性模式为建立基于线性扰动预报的区域四维变分同化系统奠定了科学基础。   相似文献   

Representations of inverse covariances by differential operators   总被引：2，自引：1，他引：1  

Qin XU 《大气科学进展》2005,22(2):181-198

In the cost function of three- or four-dimensional variational data assimilation, each term is weighted by the inverse of its associated error covariance matrix and the background error covariance matrix is usually much larger than the other covariance matrices. Although the background error covariances are traditionally normalized and parameterized by simple smooth homogeneous correlation functions, the covariance matrices constructed from these correlation functions are often too large to be inverted or even manipulated. It is thus desirable to find direct representations of the inverses of background error correlations. This problem is studied in this paper. In particular, it is shown that the background term can be written into f dx|Dv(x)|^2, that is, a squared L2 norm of a vector differential operator D, called the D-operator, applied to the field of analysis increment v(x). For autoregressive correlation functions, the D-operators are of finite orders. For Gaussian correlation functions, the D-operators are of infinite order. For practical applications, the Gaussian D-operators must be truncated to finite orders. The truncation errors are found to be small even when the Gaussian D-operators are truncated to low orders. With a truncated D-operator, the background term can be easily constructed with neither inversion nor direct calculation of the covariance matrix. D-operators are also derived for non-Gaussian correlations and transformed into non-isotropic forms.  相似文献   

梅雨锋暴雨研究中的四维变分同化试验   总被引：1，自引：0，他引：1  

程小平  王云峰  侯志明  费建芳  韩月琪 《大气科学》2005,29(3):491-495

作者利用PSU/NCAR的MM5数值预报模式及其伴随模式, 以中国1999年6月23日～24日的一次梅雨锋暴雨过程为个例, 根据气象要素与同化窗口之间的配置差异, 作了3组变分同化试验.试验结果表明: 4DVAR方法在提高梅雨锋暴雨的数值预报水平上具有重要的作用.  相似文献   

TRMM降水率资料的三维变分同化及其对"杜鹃"(0313)台风预报的改进   总被引：15，自引：6，他引：9  

丁伟钰  万齐林  端义宏 《大气科学》2005,29(4):600-608

在GRAPES(Global and Regional Assimilation and Prediction Enhanced System, 全球/区域同化预报系统)三维变分同化系统的基础上, 用改进的郭晓岚对流参数化方案作为观测算子, 来同化TRMM(Tropical Rainfall Measuring Mission, 热带降水监测计划)卫星反演的降水率资料.单点试验表明该方案通过调整背景场的水汽辐合和辐散的垂直结构, 使得同化后观测算子计算的降水率更接近实况.对台风 "杜鹃" (0313)的同  相似文献   

GPS/LEO掩星观测的变分同化技术   总被引：6，自引：0，他引：6  

刘敏  郭鹏 《天文学进展》2006,24(1):27-42

在简单介绍GPS/LEO掩星探测大气的发展历史和科学意义之后,详细阐述了反演的基本原理;分析了标准反演中存在的问题,并说明一维变分同化(1DVAR)在反演方法中的重要性;给出了一维变分同化中价值函数的求解,以及各种同化因子;简单介绍了对当前气象学中普遍使用的四维变分同化(4DVAR);重点讨论了各种同化方法,以及使用各种同化因子的优缺点。最后,通过CHAMP卫星的观测实例分析,验证了GPS数据在数值天气预报(NWP)中的作用,以及相对于标准反演法一维变分对气象要素的改进。  相似文献   

Adjoint Assimilation in Marine and an Example of Application   总被引：1，自引：1，他引：0  

XU Qing  LIU Yuguang  and LU Xianqing Physical Oceanography Laboratory  Ocean University of China  Qingdao  P.R.China 《中国海洋大学学报(英文版)》2005,4(1):14-20

This paper aims at a review of the work carried out to date on the adjoint assimilation of data in marine ecosystem models since 1995. The structure and feature of the adjoint assimilation in marine ecosystem models are also introduced. To illustrate the application of the adjoint technique and its merits, a 4-variable ecosystem model coupled with a 3-D physical model is established for the Bohai Sea and the Yellow Sea. The chlorophyll concentration data derived from the SeaWiFS ocean colour data are assimilated in the model with the technique. Some results are briefly presented.  相似文献