| 英文摘要: | This AGS PostDoctoral Research Fellow (PRF) award aims to reconstruct the paleo-monsoon of India during the previous 10,000 in order to better understand the variability of the El Nino-Southern Oscillation (ENSO) and the monsoon-ENSO teleconnection, as well as to evaluate how these mechanisms responded during a previously warm period of Earth's history.
Terrestrial records from the monsoonal region of India indicate that during the mid-Holocene epoch (approximately 5,000-6,000 years ago), climatic conditions were warmer and wetter. During this time, the northern hemisphere received greater insolation during the summer due to the precessional cycle of the Sun. However, paleoceanographic evidence of sea-surface temperatures (SSTs) reveal that the tropical Pacific was in an enhanced La Nina-like state at approximately 5,000 years,
This research seeks to evaluate two competing theories of monsoon climatology. In one theory, increased insolation strengthened the temperature gradient between the land and the ocean and, as a result, enabled an enhanced summer monsoon. In another theory, warmer and wetter conditions were due to monsoon-ENSO teleconnections.
The project aims to develop snapshots of climate fields over the past 10,000 years by combining point-proxy paleo-reconstructions using Principal Component Analysis (PCA) to reconstruct full climate fields.
Although the physical mechanisms are different, the mid-Holocene provides a potential analog, in terms of northern hemisphere temperature, to current forecasts of climate. As such, this project will explore the behavior of ENSO during this time period as a means to promote better understanding of monsoon variability and monsoon-ENSO teleconnections that will aid in monsoon forecasting.
The potential Broader Impacts involve supporting an early career scientist and helping advance the basic science of monsoonal atmospheric circulation and their environmental impacts. |