Impact of eccentricity on regional aridity-humidity variations
Dong Sunyi
Qiao Qingqing
Li Gangqiang
Abstract：Climatic aridity-humidity variations on orbital timescales are crucial for understanding the Earth's climate system response mechanisms.Investigating the relationship between orbital-scale eccentricity cycles and aridity-humidity changes helps clarify the mechanisms by which Earth's climate system responds to astronomical forcing.This paper systematically summarizes how eccentricity drives regional moisture variations by modulating precession-induced seasonal solar radiation distribution,supported by case studies from diverse regions.When Earth's orbit approaches a perfect circle(i.e.,eccentricity is close to zero),the influence of precession on the distri-bution of solar radiation is minimal,thereby weakening its capacity to modulate the climate system.In contrast,during periods of higher eccentricity,when the orbit is more elliptical,precession significantly enhances the season-al contrasts and alters the spatial and temporal distribution of climate zones.Moreover,precession determines the timing and geographic position of perihelion.For example,when Northern Hemisphere summer occurs near perihe-lion,that region receives stronger summer insolation while winter insolation decreases,intensifying seasonal tem-perature differences and exerting profound effects on precipitation and evaporation.By synthesizing geological and climatic records from multiple representative regions across Eurasia,this study analyzes how different areas re-spond to eccentricity-driven hydroclimate variability.Most existing studies suggest that high eccentricity periods are generally associated with more humid environments.This is mainly attributed to stronger seasonal contrasts un-der high eccentricity conditions,which enhance monsoonal circulation and increase precipitation in monsoon-domi-nated regions such as East Asia,South Asia,and Africa.In addition,eccentricity may exert indirect control over re-gional hydroclimate patterns through its influence on high-latitude ice sheet size and the seasonal distribution of solar radiation.However,due to variations in latitude,dominant climate systems,the type and resolution of geolo-gical records,and whether the region is influenced by ice sheets,the effects of eccentricity on regional climate are highly complex and spatially heterogeneous.For instance,in areas dominated by the westerlies or located in mid-latitudes,climate changes may show an anti-phase relationship with eccentricity cycles.In these regions,high ec-centricity may enhance processes where evaporation exceeds precipitation,strengthen monsoonal activity while suppressing the Mongolian anticyclone,or alter the position and intensity of the westerlies,leading to hydroclimate responses that are opposite to the general trend of eccentricity variation.And during low eccentricity periods,the modulation of precession amplitude is weak,resulting in a relatively stable climate that may favor vegetation growth and the maintenance of ecosystems.Therefore,when exploring the mechanisms by which eccentricity regu-lates regional hydroclimate change,it is important to avoid the mechanical application of a single region's climate response pattern.Instead,one must comprehensively consider the modulation of precession amplitude by eccentri-city,as well as key regional factors such as geographic location,paleogeographic setting,geological record type,and the developmental stage of ice sheets,to conduct more targeted and systematic analyses.
Keywords：Earth's orbital parameterseccentricityprecessionaridity-humidity variations
Publication Date：2026-03-31
Online Publishing Date：2025-11-07(First online date of this platform, not the publication date of the document)
Pages：16( 148-163 )