Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics,...Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.展开更多
Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） sinc...Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） since the Middle Holocene in the study area. The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods： strong and highly fluctuating during 7.2-4.2 ka BP; moderate and relatively stable during 4.2-1.8 ka BP; and weakened during 1.8-0 ka BP. Compared with the East Asian Summer Monsoon （EASM） recorded in the previous studies, the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM. At the centennial scale, however, the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations （Bond events 0 to 5） within the dating error, most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.展开更多
Based on MC-ICP-MS U-series dating and stable O-isotope analysis results, a 4―5 years resolution monsoon record over the past 1000 years has been estab- lished for two stalagmites from Dongge Cave, Guizhou. The high ...Based on MC-ICP-MS U-series dating and stable O-isotope analysis results, a 4―5 years resolution monsoon record over the past 1000 years has been estab- lished for two stalagmites from Dongge Cave, Guizhou. The high resolution oxygen isotope record serves as a proxy for variations in rainfall of Asian southwest monsoon over the Yunnan-Guizhou Plateau. A close relation of the δ 18O record with the ?14C record from tree rings largely reflects impact of centennial-scale solar activity on the monsoon climate changes. The conspicuous decrease in the δ 18O value at AD 1720 indicates an abrupt increase in monsoon rainfall, sug- gesting that an atmospheric-oceanic couple over the tropical Indian Ocean plays an important role in rapid increase of the Northern Hemisphere temperature over the last century.展开更多
Evidence for the '8.2 ka cold event' has been provided mostly from the circum-North Atlantic area. However, whether this cold event occurred in other places is a key to understanding its cause. Here, we provid...Evidence for the '8.2 ka cold event' has been provided mostly from the circum-North Atlantic area. However, whether this cold event occurred in other places is a key to understanding its cause. Here, we provide the evidence for the '8.2 ka cold event' from the Guliya ice core in the northwest Tibetan Plateau, and it was found that the peak cooling (-8.3-8.2 ka) in this ice core was about 7.8-10°C, which was larger than the cooling in the North Atlantic region. The primary causes for this episode were diminished solar activity and weakened thermohaline circulation. Moreover, another weak cold event, centered about 9.4 ka, was also recorded in the Guliya ice core record. These two cold events were concurrent with the ice-rafting episodes in the North Atlantic during the early Holocene, which implies that the millennial-scale climatic cyclicity might exist in the Tibetan Plateau as well as in the North Atlantic.展开更多
基于神农架青天洞石笋两个230Th年龄、582条纹层计数和183个氧同位素数据,重建了7～6 ka B.P.期间平均3年分辨率的1δ8O变化序列。持续约580年振幅达1.8‰的δ18O在平均值-9.66‰上下波动,指示了东亚季风降水强度的长期演化趋势和高频...基于神农架青天洞石笋两个230Th年龄、582条纹层计数和183个氧同位素数据,重建了7～6 ka B.P.期间平均3年分辨率的1δ8O变化序列。持续约580年振幅达1.8‰的δ18O在平均值-9.66‰上下波动,指示了东亚季风降水强度的长期演化趋势和高频振荡信息,大致划分为4个百年尺度旋回。青天洞与阿曼石笋δ18O记录的对比表明,东亚季风和印度季风在百年或更短时间尺度上同相位变化,可能反映了两地季风气候受统一的印度洋/太平洋大尺度水汽循环控制。功率谱分析揭示出163、81、16和11年的周期,大致与树轮Δ14C百年至数十年尺度太阳活动变化周期相同。展开更多
基金supported by the National Natural Science Foundation of China (40725014)the Specialized Research Fund for State Key Laboratories
文摘Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.
基金supported by National Basic Research Program of China (Grant No. 2010CB428901)National Natural Science Foundation of China (Grant Nos. 40976036 and40676032)Open Foundation of the State Key Laboratory of Loess and Quaternary Geology (Grant No. SKLLQG1107)
文摘Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） since the Middle Holocene in the study area. The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods： strong and highly fluctuating during 7.2-4.2 ka BP; moderate and relatively stable during 4.2-1.8 ka BP; and weakened during 1.8-0 ka BP. Compared with the East Asian Summer Monsoon （EASM） recorded in the previous studies, the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM. At the centennial scale, however, the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations （Bond events 0 to 5） within the dating error, most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.
基金This work was supported by the National Outstanding Youth Foundation of China(Grant No.40225007)the 973 Project(Grant No.2004CB20204).
文摘Based on MC-ICP-MS U-series dating and stable O-isotope analysis results, a 4―5 years resolution monsoon record over the past 1000 years has been estab- lished for two stalagmites from Dongge Cave, Guizhou. The high resolution oxygen isotope record serves as a proxy for variations in rainfall of Asian southwest monsoon over the Yunnan-Guizhou Plateau. A close relation of the δ 18O record with the ?14C record from tree rings largely reflects impact of centennial-scale solar activity on the monsoon climate changes. The conspicuous decrease in the δ 18O value at AD 1720 indicates an abrupt increase in monsoon rainfall, sug- gesting that an atmospheric-oceanic couple over the tropical Indian Ocean plays an important role in rapid increase of the Northern Hemisphere temperature over the last century.
基金This work was supported by the Chinese National Committee of Science and Technology (Grant No. G1998040800)the Chinese Academy of Sciences (Grant No. KZCX1-10-02)+1 种基金 the National Natural Science Foundation of China (Grant No. 49801004) the US NSF-ESH
文摘Evidence for the '8.2 ka cold event' has been provided mostly from the circum-North Atlantic area. However, whether this cold event occurred in other places is a key to understanding its cause. Here, we provide the evidence for the '8.2 ka cold event' from the Guliya ice core in the northwest Tibetan Plateau, and it was found that the peak cooling (-8.3-8.2 ka) in this ice core was about 7.8-10°C, which was larger than the cooling in the North Atlantic region. The primary causes for this episode were diminished solar activity and weakened thermohaline circulation. Moreover, another weak cold event, centered about 9.4 ka, was also recorded in the Guliya ice core record. These two cold events were concurrent with the ice-rafting episodes in the North Atlantic during the early Holocene, which implies that the millennial-scale climatic cyclicity might exist in the Tibetan Plateau as well as in the North Atlantic.
文摘基于神农架青天洞石笋两个230Th年龄、582条纹层计数和183个氧同位素数据,重建了7～6 ka B.P.期间平均3年分辨率的1δ8O变化序列。持续约580年振幅达1.8‰的δ18O在平均值-9.66‰上下波动,指示了东亚季风降水强度的长期演化趋势和高频振荡信息,大致划分为4个百年尺度旋回。青天洞与阿曼石笋δ18O记录的对比表明,东亚季风和印度季风在百年或更短时间尺度上同相位变化,可能反映了两地季风气候受统一的印度洋/太平洋大尺度水汽循环控制。功率谱分析揭示出163、81、16和11年的周期,大致与树轮Δ14C百年至数十年尺度太阳活动变化周期相同。
