Upstream Cyclone Influence on the Predictability of Block Onsets over the Euro-Atlantic Region
Upstream Cyclone Influence on the Predictability of Block Onsets over the Euro-Atlantic Region
复制标题
上游气旋对欧洲大西洋地区块体爆发可预测性的影响
DOI：
10.1175/mwr-d-18-0226.1
复制
发表时间：
2019
影响因子：
3.2
通讯作者：
Gray S
中科院分区：
文献类型：
--
作者：
Gray S
大气阻塞已被证明是一种模式难以准确预测的现象，特别是在纬向气流之后出现阻塞状态。这种困难部分是由于缺乏一个完整的阻塞发生和维持的动力学理论。在这里，我们评估了来自北大西洋波导和下游影响实验场运动的两个案例研究中的影响气旋代表对块开始预测的影响，以及来自ECMWF的中期预测中欧洲-大西洋地区20个最不可预测的块开始。在个案研究中，对阻塞开始的6天预测，对在开始前几天上游气旋（一个个案为一个气旋，另一个个案为两个气旋）的预测位置和强度的变化很敏感。集合灵敏度分析显示，在不可预测的阻塞开始情况下，情况往往是这样：在阻塞开始前2 - 3天，上游气旋附近1000-hPa位势高度或对流层顶附近320-K位势涡度发生一个标准差变化，在分析的20个开始情况中，有17个的阻塞面积在开始日发生超过10%的变化。这些结果表明，对上游气旋位置和强度的预报的改进可能有助于改善块状开始预报。
Atmospheric blocking has been shown to be a phenomenon that models struggle to predict accurately, particularly the onset of a blocked state following a more zonal flow. This struggle is, in part, due to the lack of a complete dynamical theory for block onset and maintenance. Here, we evaluate the impact cyclone representation had on the forecast of block onset in two case studies from the North Atlantic Waveguide and Downstream Impact Experiment field campaign and the 20 most unpredictable block onsets over the Euro-Atlantic region in medium-range forecasts from the ECMWF. The 6-day forecast of block onset in the case studies is sensitive to changes in the forecast location and intensity of upstream cyclones (one cyclone for one case and two for the other case) in the days preceding the onset. Ensemble sensitivity analysis reveals that this is often the case in unpredictable block onset cases: a one standard deviation change in 1000-hPa geopotential height near an upstream cyclone, or 320-K potential vorticity near the tropopause, two or three days prior to block onset is associated with more than a 10% change in block area on the analyzed onset day in 17 of the 20 onset cases. These results imply that improvement in the forecasts of upstream cyclone location and intensity may help improve block onset forecasts.
登录
查看更多内容
影响因子：
8.9
作者：
C. Grams;H. Wernli;M. Böttcher;J. Čampa;U. Corsmeier;S. Jones;J. Keller;C. Lenz;L. Wiegand-
通讯作者：
C. Grams;H. Wernli;M. Böttcher;J. Čampa;U. Corsmeier;S. Jones;J. Keller;C. Lenz;L. Wiegand-
影响因子：
8.9
作者：
J. Chagnon;S. Gray;J. Methven
通讯作者：
J. Chagnon;S. Gray;J. Methven
影响因子：
4.9
作者：
Adam A. Scaife;T. Woollings;J. Knight;G. Martin;T. Hinton
通讯作者：
Adam A. Scaife;T. Woollings;J. Knight;G. Martin;T. Hinton
罗斯贝波结构的系统模型预报误差
影响因子：
5.2
作者：
Gray S
通讯作者：
Gray S
影响因子：
3.7
作者：
B. Harvey;J. Methven;M. Ambaum
通讯作者：
M. Ambaum