On the Causes of Synoptic‐Scale Eddy Heat Flux Decline

Abstract The poleward heat flux by atmospheric waves plays a pivotal role in maintaining the meridional temperature gradient. A recent study found that Northern Hemisphere transient eddies has been weakening, and attributed this weakening to smaller equator‐to‐pole gradient caused Arctic warming. During period of 1979–2019 examined here, for annual mean, both synoptic‐scale eddy had indeed declined. However, from October April, trend is more closely tied planetary‐scale trend, than trend. From June August, decline can be warming high‐latitude land areas. Therefore, comprehensive interpretation needs include dynamics summer