Abstract/Summary

We identify for the first time an Indian Easterly Jet (IEJ) in the mid-troposphere during the pre-monsoon using reanalysis data. The IEJ is weaker and smaller than the African Easterly Jet over West Africa, with a climatological location of 10°N, 60–90°E, 700 hPa, and strength 6–7 m s−1 during March–May. The IEJ is a thermal wind associated with low-level meridional gradients in temperature (positive) and moisture (negative), resulting from equatorward moist convection and poleward dry convection. The IEJ is associated with a negative meridional potential vorticity gradient, therefore satisfying the Charney-Stern necessary condition for instability. However, no wave activity is detected, suggesting that the potential for combined barotropic-baroclinic instability is not often realized. IEJ strong (weak) years feature increased (reduced) near-surface temperatures and drier (wetter) conditions over India. This study provides an introduction to the IEJ's role in pre-monsoon dynamics, and a platform for further research.