Comparing diagnosed observation uncertainties with independent estimates: A case study using aircraft-based observations and a convection-permitting data assimilation system
Comparing diagnosed observation uncertainties with independent estimates: A case study using aircraft-based observations and a convection-permitting data assimilation system
复制标题
将诊断的观测不确定性与独立估计进行比较：使用机载观测和允许对流数据同化系统的案例研究
DOI：
10.1002/asl.1029
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发表时间：
2021
影响因子：
3
通讯作者：
Mirza A
中科院分区：
文献类型：
--
作者：
Mirza A
飞机可以使用飞机气象数据中继器报告环境温度的现场观测结果，也可以使用模式选择增强型跟踪数据(S模式EHS)得出这些数据。这些观测结果可以被同化到数值天气预报模式中，以改善预报的初始条件。同化过程根据观测的测量和表示的预期不确定度对观测进行加权。本文的目的是比较从数据同化统计诊断的观测不确定性和独立估计。为了量化这些独立的估计，我们使用了使用现场研究级仪器进行的计量比较，以及使用飞机(主要是AMDAR报告)与其他观测系统(如无线电探空仪)之间的配置方法进行的先前研究。在这项研究中，我们利用气象局有限区域三维变分同化系统(3 公里水平网格长度，3小时周期)的观测-负-背景和观测-负分析统计，诊断了不确定性方差的垂直结构的新估计。这种不确定度估计方法计算简单，但有几个局限性。然而，由此产生的诊断方差具有垂直结构，类似于独立的不确定性估计所提供的结构。这提供了对不确定性估计方法的信心，以及对诊断的不确定性估计本身的信心。在未来，我们的方法与其他结果一起，可以提供估计基于飞机的温度观测同化的不确定性的方法。
Aircraft can report in situ observations of the ambient temperature by using aircraft meteorological data relay (AMDAR) or these can be derived using mode‐select enhanced tracking data (Mode‐S EHS). These observations may be assimilated into numerical weather prediction models to improve the initial conditions for forecasts. The assimilation process weights the observation according to the expected uncertainty in its measurement and representation. The goal of this paper is to compare observation uncertainties diagnosed from data assimilation statistics with independent estimates. To quantify these independent estimates, we use metrological comparisons, made with in‐situ research‐grade instruments, as well as previous studies using collocation methods between aircraft (mostly AMDAR reports) and other observing systems such as radiosondes. In this study we diagnose a new estimate of the vertical structure of the uncertainty variances using observation‐minus‐background and observation‐minus‐analysis statistics from a Met Office limited area three‐dimensional variational data assimilation system (3 km horizontal grid‐length, 3‐hourly cycle). This approach for uncertainty estimation is simple to compute but has several limitations. Nevertheless, the resulting diagnosed variances have a vertical structure that is like that provided by the independent estimates of uncertainty. This provides confidence in the uncertainty estimation method, and in the diagnosed uncertainty estimates themselves. In the future our methodology, along with other results, could provide ways to estimate the uncertainty for the assimilation of aircraft‐based temperature observations.