Reconstruction and analysis of the variation of astronomical seasonal length since 12000 years BP
Previous studies have found that seasonal length changes are closely related to climate changes,but so far there is no highly accurate seasonal length change sequence with a length exceeding 10000 years.This article uses ephemeris data DE441 to reconstruct the time series of seasonal length changes since 12000 years,and uses two methods,ICEEMDAN and continuous wavelet transform,to extract periodic signals of different scales of summer and winter length,revealing their changing characteristics in different time periods over the past 12000 years.Research has found that there are cycles of 2.5 years,4 years,5.5 years,11.8 years,15.8 years,29 years,84 years,101 years,223 years,approximately 500 years,and approximately 850 years in the summer duration of the Northern Hemisphere,while there are cycles of 2.5 years,4 years,5.5 years,11.8 years,15.8 years,29 years,74 years,167 years,approximately 500 years,and approximately 1000 years in the winter duration of the Northern Hemisphere.The short scale periodic variation of 11.8 years runs through the entire past 12000 years;The cycles of 2.5 years,4 years,5.5 years and 15.8 years are relatively significant in a certain period of Holocene.The research results provide new data and basis for further understanding and exploring the causes and mechanisms of climate change.
NETL
NSTL
万方数据
