Science Update: Contrasting effects of El Niño variants on stratospheric water vapour

C.I. Garfinke and co-authors present new results in GRL regarding the contrasting impacts of different El Niño types on stratospheric water vapour. Making use of chemistry-climate model, they find that the seasonality and location of peak sea surface temperature (SST) warming impacts the amount of water vapour entering the stratosphere. El Niño events with maximum SST warming in the eastern Pacific in spring result in warming at the tropopause above the warm pool region, leading to more water vapour entering the stratosphere. In contrast, El Niño events with peak warming in the central Pacific in autumn and early winter result in non-uniform warming above the warm pool region and less water vapour entering the stratosphere. Differences in lower stratospheric water vapour between the two El Niño variants approach 0.3ppmv, while differences between spring and autumn responses are greater than 0.5ppmv. The full abstract can be found here.