Impact of late winter sea surface temperature seesaw between equatorial central Pacific and Philippine Sea on early spring vegetation over the low-latitude highlands of China

Abstract

In this study, the impact of late winter (January-February) sea surface temperature (SST) seesaw between equatorial central Pacific and Philippine Sea on early spring (March-April) vegetation interannual variation over the low-latitude highlands of China (CLLH) is investigated. The positive phase of late winter seesaw SST pattern, characterized by warmer(colder)-than-normal SSTs in the equatorial central Pacific (Philippine Sea), favors early spring CLLH vegetation growth. From the local perspective, the positive phase of late winter SST seesaw results in stronger(higher)-than-normal precipitation (surface air temperature) in the west (east) of the CLLH, these abnormal signals may be recorded by land surface and may persist to early spring, and this wetter(warmer)-than-normal land surface condition in the west (east) of the CLLH favors local vegetation growth. For the atmospheric circulation anomalies, the positive phase of late winter seesaw SST pattern contributes to an anomalous anticyclone over Philippine Sea in lower troposphere. On one hand, anomalous northerly winds on the eastern flank of this anomalous cyclone advect off-equatorial dry and cold air to the Maritime Continent and cause precipitation reduction there, consequently an anomalous anticyclone over the tropical north Indian Ocean in lower troposphere is excited via a Gill-type Rossby wave atmospheric response. This anomalous anticyclone leads to enhanced water vapor transport and increased precipitation in the west of the CLLH resultantly. On the other hand, southerly wind anomalies being the western flank of the anomalous anticyclone advect warm air to the east of the CLLH, result in increased surface air temperature there.