The Madden Julian oscillation (MJO) has a systematic influence on the state of the extratropical atmosphere. The physical mechanism involves teleconnections from tropical deep convective heat sources through wave propagation. MJO heating resembles a propagating dipole that cycles through phases on a timescale similar to the response timescale. This complicates the attribution of the response to a well identified phase in the tropical heat source. In this paper the Dynamical Research Empirical Atmospheric Model (DREAM) is used to examine the extratropical response to a moving cyclic MJO-like tropical heat source based on outgoing long-wave radiation data. A set of ensemble forecast experiments and consistent stationary wave solutions are analysed, together with longer equilibrium integrations, to investigate how the extratropical response relates to the phase of the MJO heating. We find that the response is modified by the propagation of the source in a way that depends on the initial phase. It also displays both stationary and transient nonlinearity which can account for an asymmetric response to opposite-phase dipole heat sources. The solution for Indian Ocean heating/West Pacific cooling is more zonally oriented and weaker than the solution for the opposite phase. If the MJO heat source is specified as a continuous cycle, it modifies the time-mean extratropical circulation and generates remote teleconnections. The timing and starting phase of MJO events can greatly modify the relationship between MJO phase and extratropical response, especially when an unforced “resting” period is inserted between simulated MJO cycles.

Madden Julian振荡（MJO）对温带大气状态有系统的影响。物理机制涉及热带深对流热源通过波传播的遥相关。MJO加热类似于传播的偶极子，该偶极子在类似于响应时间尺度的时间尺度上循环进行。这使响应的归因于热带热源中一个公认的阶段变得复杂。本文使用动力学研究经验大气模型（DREAM），基于传出的长波辐射数据，研究了对移动式MJO类热带热源的温带响应。分析了一组整体预报实验和一致的平稳波解，以及更长的平衡积分，研究温带响应如何与MJO加热阶段相关。我们发现响应被源的传播以某种方式修改，该方式取决于初始阶段。它还显示平稳和瞬态非线性，这可以解释对反相偶极热源的不对称响应。印度洋加热/西太平洋冷却的解决方案比相向的解决方案更偏向区域性且较弱。如果将MJO热源指定为连续循环，则它将修改时间平均温带环流并生成远程遥距连接。MJO事件的时间和开始阶段可以极大地改变MJO阶段与温带响应之间的关系，尤其是在模拟的MJO周期之间插入非强制的“静止”期时。