RECONSTRUCTION AND CHARACTERIZATION OF THE 30° N WINTER AND SUMMER HALF-YEAR ASTRONOMICAL SOLAR IRRADIATION CHANGE SERIES SINCE 12000 YEARS
To investigate the effects of seasonal duration and solar irradiance changes on solar irradiation variations over the past 12000 years,this study reconstructs the sequence of 30°N seasonal half-year solar irradiation changes using the ephemeris data DE441.The periodic signals of the 30° N winter and summer half-year solar irradiation on different scales were extracted utilizing the Hilbert-Huang transformation method to reveal their dynamic change characteristics.Additionally,generalized additive models were employed to assess the explanatory power of solar irradiance and duration on irradiation changes across different time periods and time scales.The results indicate the following:(1)The winter half-year solar irradiation reached its minimum approximately 9000 a B.P.and has gradually increased since then.Conversely,summer half-year solar irradiation peaked approximately 9000 a B.P.and has gradually decreased since.The disparity between winter and summer solar irradiation was the greatest approximately 9000 a B.P.and has gradually narrowed since then.These findings correlate with the strengthened monsoon phenomenon during that period.(2)The magnitude of solar irradiation change in the winter half-year is greater than that in the summer half-year,with the annual trend of solar irradiation change mirroring that of the winter half year.This consistency helps explain the warming pattern observed in Holocene paleoclimate simulations,as these models often uses annual solar irradiation as a boundary condition.(3)Summer half-year irradiation variations exhibit dominant cycles of approximately 2.7,5.2,9.0,20.6,41.2,88.5,238.1,270.3 and 350 years,whereas winter half-year irradiation variations show cycles of roughly 2.7,5.3,11.9,19.3,47.6,84.8,263.2,270.3 and 350 years.The 2.7-year and 270.3-year cycles are the most prominent but show inconsistent fluctuations over the past 12000 years.The 2.7-year cycle is more significant in winter during the early-mid period and in summer during the mid-late period.The 270.3-year cycle is notable in both seasons,particularly during the early-mid period.(4)The explanatory power of solar irradiance and seasonal duration to solar irradiation varies between winter and summer halves as well as across different scales of change.Over the past 12000 years,on an interannual scale,the explanatory power of irradiance to irradiation change during the winter and summer halves exhibits differing trends.Specifically,from early to late,the explanatory power to summer half irradiation change gradually increases,while the explanatory power to winter half irradiation change gradually decreases.However,on a centennial scale,the trends of both seasons are consistent,indicating that the explanatory power of irradiance changes to irradiation changes is greater in the early period and smaller in the late period.On the interannual scale,the explanatory power of summer duration to irradiation change is greater in the late period,while that of winter duration is more significant in the early period.On the centennial scale,the explanatory power of both winter and summer duration changes to irradiation change is highest in the early period.
solar irradiationseasonal half-yearsequence reconstructionperiodtimescaleHolocene
万方数据
维普
