科研之友
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摘要
Previous studies have revealed that extratropical forcing can lead to changes in the intertropical convergence zone (ITCZ). Based on reanalysis data from 1979 to 2019, this paper discusses the influence of the South Pacific Ocean Dipole (SPOD, a dominant mode between the subtropics and extratropics in the South Pacific) and its coordination with ENSO in the ITCZ. Results show that SPOD has an effect on the position and intensity of the ITCZ, especially in the region around Nino4. From the latitudes of ITCZ axes and precipitation averaged over 160 degrees E-160 degrees W, positive (negative) SPOD events force a northward (southward) shift in the ITCZ in boreal winter (DJF), while the position moves in the opposite direction in boreal summer (JJA). In addition, ENSO can obviously enhance the influence of SPOD on the ITCZ. It is evident that there is a wider range of northward (southward) shift in the ITCZ under both positive SPOD and El Nino (negative SPOD and La Nina) conditions during DJF. Similar to DJF, both positive SPOD and El Nino (negative SPOD and La Nina) events still cause the ITCZ to move toward (away from) the equator during JJA, except that the magnitude of the movement in JJA is less than that in DJF. Precipitation averaged over 160 degrees E-160 degrees W is at a maximum under both positive SPOD and El Nino events, which have the greatest influence on ITCZ intensity, followed by both negative SPOD and La Nina in DJF, while in JJA, ITCZ intensity is most sensitive to negative SPOD events.
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单位复旦大学
