ENSO teleconnections - Analysis of time lag between tropical Pacific sea surface temperature and climate and vegetation anomalies

Abstract: El Niño-Southern Oscillation (ENSO) affects weather and climate in regions spread all around the Earth via teleconnections. While quite a lot of research has been done on recognizing what regions are affected by these and what is the sign of the associated temperature, rainfall and vegetation anomalies, not that much attention has been paid to the timing of the impacts with respect to the ENSO state. This project found that the ENSO-caused anomalies were never at their peak simultaneously with an ENSO event culmination for any of the three examined variables – precipitation, temperature and normalized difference vegetation index (NDVI) – in any of the eight study areas. It was also found that there is no seasonally uniform time lag between sea surface temperature (SST) anomalies in tropical Pacific and the associated anomalies in a specific region. On the contrary, the anomalies are generally strongest in late northern hemisphere spring to early northern hemisphere summer for all the variables in all the regions and that they are mainly affected by the ENSO state in the preceding northern hemisphere summer and northern hemisphere winter. Since these findings were not expected in comparison with studies already published, it seems necessary to test the time lag between tropical Pacific SST and impacts of ENSO teleconnections in more studies with possibly diverse methodologies before drawing conclusions that would revise the so far published knowledge about the timing of ENSO teleconnections impacts as suggested by the results of this study.