Possible impact of solar activity on the convection dipole over the tropical pacific ocean

Abstract

The impact of solar activity (F10.7) on tropical Pacific convection during the boreal summer (June–July–August, JJA) has been examined using reanalysis data, revealing a significant lagged (1–2 years) correlation between outgoing long-wave radiation (OLR) over the tropical western Pacific and the F10.7 index. The OLR anomaly over the tropical western Pacific and the maritime continent shows a dipole pattern during the 1–2 years following high solar (HS) years. Furthermore, the first mode of the empirical orthogonal function (EOF) analysis on the OLR with the El Niño/Southern Oscillation (ENSO) signal removed is similar to the distribution of correlation coefficients between the JJA mean F10.7 index and the OLR with ENSO signal removed. The correlation and composite analyzes of the OLR, velocity potential and vertical velocity reveals that this convection dipole pattern shows an eastward shift of the central position of deep convection, as related to the influence of solar activity over the tropical western Pacific. Further analyzes show that the evolutionary process of the solar signal in the ocean–atmosphere system over the tropical western Pacific is consistent with the analyzes of OLR, velocity potential, and vertical velocity. By modulating vertical air temperature, the solar signal in the tropical sea surface temperature (SST) may contribute to the triggering of a lagged convection dipole pattern.