Large‐scale (500 ≤ r ≤ 2,200 km) outgoing long‐wave radiation (OLR) and water vapour (WV) fields are investigated in satellite observations over the Pacific, linked to ERA‐5 reanalysis data and the ECMWF ensemble forecasts of tropical cyclones (TC) globally. A large‐scale OLR dipole pattern of low and high fluxes are found in both the observations and model. As expected, a low OLR region is positioned within the TC circulation, but there is also a robust high OLR region poleward and west of the TC centre. A dry “black hole” on WV grey‐scale imagery occupies the same region of high OLR. Relative to the central low OLR TC signal, the typical dipole magnitude, distance and orientation of the high OLR regions are 230 W·m⁻², 1,150 km, and 145° anticlockwise from east. From the reanalysis we find that the interaction between the vortex and the environmental flows produces upper‐level convergence, low‐level divergence and subsidence throughout the troposphere in the region of high OLR. Analysis of the ECMWF model shows that the position of the high OLR region rotates anticlockwise about the TC centre as the TC moves from westward to eastward. Through use of a sub‐ensemble, we test if capturing the high OLR anomaly has a significant relationship with TC track. We apply a perfect model approach and find that sub‐ensembles that are composed of models whose large‐scale OLR fields closely match the target TC also have a better track. This improvement is mostly attributed to the high OLR component of the dipole.

中文翻译：

---

热带气旋的偶极子出射长波辐射

大规模（500≤  [R  ≤2200公里）传出的长波辐射（OLR）和水蒸汽（WV）字段在卫星观测在太平洋调查，挂ERA-5再分析数据和热带气旋的ECMWF集合预报（TC）全球。在观测值和模型中都发现了大通量的低通量和高通量的OLR偶极子图。不出所料，低OLR区域位于TC循环内，但在TC中心偏西和偏西也有一个健壮的高OLR区域。WV灰度图像上的干燥“黑洞”占据了高OLR的相同区域。相对于中央低OLR TC信号，高OLR区域的典型偶极子幅度，距离和方向为230 W·m ^-2，1150公里和从东逆时针旋转145°。通过重新分析，我们发现涡旋与环境流之间的相互作用在高OLR区域的整个对流层产生了高层收敛，低层发散和沉降。对ECMWF模型的分析表明，当TC从西向东移动时，高OLR区域的位置围绕TC中心逆时针旋转。通过使用子合奏，我们测试捕获高OLR异常是否与TC轨道有显着关系。我们应用了完美的模型方法，发现由大型OLR场与目标TC紧密匹配的模型组成的子集合也具有更好的轨迹。这种改善主要归因于偶极子的高OLR分量。