Can ENSO-like convection force an ENSO-like extratropical response on subseasonal timescales?

Recent studies using a simple dry general circulation model forced with heating based on El Niño and La Niña precipitation show corresponding El Niño-like and La Niña-like extratropical responses 7-10 days later. Observational studies based on the Madden-Julian Oscillation also suggest a similar time delay for the extratropical response. However, since the El Niño/Southern Oscillation (ENSO) phenomenon has a multi-seasonal to multi-annual time scale, the observed extratropical response is generally considered on similar time scales, and the question of the observed time delay between the forcing and the response is largely ignored. In this study, daily indices of El Niño-like convection and La Niña-like convection, are calculated, and events during the Northern Hemisphere winter season when these daily indices have local maxima in time are identified. After calculating composites of 300-hPa geopotential height over the North Pacific and North America, the time delay for the extratropical response is determined. It is found that, for El Niño, there is a 5-8 day time delay between the peak of El Niño-like convection and the El Niño-like response. Interestingly, the height response to brief peaks in El Niño-like convection favors a more PNA-like trough over eastern North America, compared with a ridge over northeastern North America in the overall El Niño height composite. For La Niña, there is a double peak in the La Niña-like extratropical response, peaking around lag day 4, and again around lag day 11. The results of this study show that when there is a clear association between El Niño-like convection and an El Niño-like height response (and similarly for La Niña-like convection and a La Niña-like height response), the response is delayed by only 5-10 days, consistent with initial-value calculations with numerical models and with observations of intraseasonal phenomena such as the Madden-Julian Oscillation.