Forecast Sensitivity to Regional and Global Targeting of the Initial State

9714291 Paegle美国天气研究计划（USWRP）是一项跨部门活动，旨在执行和实施必要的研究，以改善向全国提供的天气服务。根据该计划，国家科学基金会、国家海洋和大气管理局、国家航空航天局和海军研究办公室将联合评估和支持USWRP的高优先级研究。在这项研究中，首席研究员将研究区域和全球尺度的初始不确定性对模式预测敏感性的相对贡献。最近的几项研究强调了基于伴随模式、“繁殖模式”和奇异向量分析产生的不确定性增长估计的局部目标观测的好处。这种方法识别动态不稳定区域，其中局部初始状态的细节可能与随后的预测演变有特殊关系。目前尚不清楚这些方法是否区分了由于全球尺度背景流的不确定规格而导致的预测敏感性。1996年3月12日至14日“超级风暴”的样本预报表明，上游区域的细节，包括导致风暴的初始位涡极大值，对于96小时的预报是重要的。这些发现激发了所提议的工作，即估计大气状态规范中的不确定性，并将不确定性对数值天气预报的影响量化为不确定性位置和尺度的函数。本研究的工作假设是，局部天气预报的数值方法往往更敏感地依赖于相对较小的初始全球尺度状态的不确定性，而不是初始区域状态的不确定性。将比较三种独立的全球再分析产品。不同的、同样可信的大气分析的差异提供了初始状态当前不确定性的度量，并将被光谱量化。这样估计的不确定性将被插入到一个全局变分辨率模型的初始状态中，以确定后续预测灵敏度的尺度依赖性。敏感性研究将侧重于从春季和冬季条件中选择的一些初始状态。最初的目标领域还将包括太平洋数据空白。这项研究的成功完成可能会对业务预测的数据收集策略产生重要影响。＊＊＊

9714291 Paegle The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation, the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration and the Office of Naval Research are jointly evaluating and supporting research of high priority to the USWRP. In this research, the Principal Investigator will investigate the relative contributions of regional and global-scale initial uncertainties on model forecasting sensitivity. Several recent studies emphasize benefits of locally targeted observations, based upon estimates of uncertainty growth produced by adjoint, "bred mode", and singular vector analyses. Such methods identify dynamically unstable regions within which details of the local initial state may have special relevance for subsequent forecast evolution. It is unclear whether those approaches distinguish forecast sensitivities due to slightly uncertain specification of the global-scale, background flow. Sample forecasts of the "superstorm" of 12-14 March 1996 suggest that details of the upstream domain that includes the initial potential vorticity maxima leading to the storm are important for a 96 h forecast. Such findings motivate the proposed work which will estimate uncertainty in specification of the atmospheric state, and will quantify impact of the uncertainty upon numerical weather prediction as a function of uncertainty location and scale. The working hypothesis of the research is that local weather prediction by numerical methods often depends more sensitively on relatively small uncertainties of the initial global-scale state than upon uncertainties of the initial regional state. Three separate global reanalysis products will be compared. The differences of different, equally credible atmospheric analyses prov ide a measure of current uncertainty in the initial state, and will be spectrally quantified. The uncertainties thus estimated will be inserted into the initial states of a global variable resolution model to determine the scale dependence of subsequent forecast sensitivity. Sensitivity studies will focus on a number of initial states selected from Spring and Winter conditions. Initially targeted domains will also include the Pacific data void. Successful completion of this research potentially will have important implications for data collection strategies for operational forecasting. ***