In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchrono...In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchronous in phase space at all period scales, and the former lags behind the latter, which implies our results are supported for the integral response model; （ii） their different definitions and physical meanings may be a major reason for their phase asynchrony between them, and the solar flare activity favor to be related to the magnetic complex rather than magnetic strength.展开更多
A higher correlation tends to yield a more accurate prediction,so that a correlation as high as possible has been searched for and employed in the prediction of solar activity.Instead of using geomagnetic activity dur...A higher correlation tends to yield a more accurate prediction,so that a correlation as high as possible has been searched for and employed in the prediction of solar activity.Instead of using geomagnetic activity during the descending phase of the solar cycle,the minimum annual aa index (aa min) is used as an indicator for the ensuing maximum amplitude (R m) of the sunspot cycle.A four-cycle periodicity is roughly shown in the correlation between R m and aa min.The widely accepted Ohl's precursor prediction method often fails due to the prediction error relative to its estimated uncertainty.An accurate prediction depends on the positive variation of the correlation rather than a higher correlation.Previous experiences by using this method indicate that a prediction for the next cycle,R m (24)=80 ± 17,is likely to fail,implying that the sunspot maximum of Cycle 24 may be either smaller than 63 or greater than 97.展开更多
The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variat...The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.展开更多
Hot Flow Anomalies (HFAs) are phenomena that frequently appear in the vicinity of the Earth's bow shock. We have identified 765 HFA events with Cluster spacecraft data from 2003 to 2009. We study the plasma and ma...Hot Flow Anomalies (HFAs) are phenomena that frequently appear in the vicinity of the Earth's bow shock. We have identified 765 HFA events with Cluster spacecraft data from 2003 to 2009. We study the plasma and magnetic field variations during typical HFAs. Then we study the average structure of HFAs using the superposed epoch method during a 200 s time interval, with the HFA onset time as the epoch time. The results show that HFAs can be classified into four classes based on variations of the dynamic pressure over time, namely "-+" (down-up), "+-" (up-down), "M" (up-down-up) and "W" (up-down-up-down-up), where the letters represent similar shapes with the variation trends of the dynamic pressure. Trends of other parameters are highly related to those of the dynamic pressure with obvious characteristics of the classification. Moreover, statistical results suggest that the number of HFA events varies in years. Compared with the speed of solar wind and sunspot number, the number of HFA events in each year has positive correlation with the former, while it has little relation with the latter. The result of this paper will provide data base for further studies on the mechanisms of the formation, the structural evolution and other relative questions of HFAs.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11003041 and 11203006)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2009AM021,ZR2012AQ029,ZR2012AM008 and ZR2010AL025)+1 种基金Dezhou University Foundation(Grant No.402126)supported by Open Research Program of Key Laboratory for the Structure and Evolution of Celestial Objects,Chinese Academy of Sciences(Grant No.OP201102)
文摘In this paper, the relative phase relationship between flare index and sunspot activity （sunspot numbers and sunspot areas） is investigated. It is found that （i） the flare index and sunspot activity are asynchronous in phase space at all period scales, and the former lags behind the latter, which implies our results are supported for the integral response model; （ii） their different definitions and physical meanings may be a major reason for their phase asynchrony between them, and the solar flare activity favor to be related to the magnetic complex rather than magnetic strength.
基金supported by the Chinese Academy of Sciences (Grant No.KGCX3-SYW-403-10)the National Natural Science Foundation of China (Grant Nos.10973020,10673017 and 40890161)
文摘A higher correlation tends to yield a more accurate prediction,so that a correlation as high as possible has been searched for and employed in the prediction of solar activity.Instead of using geomagnetic activity during the descending phase of the solar cycle,the minimum annual aa index (aa min) is used as an indicator for the ensuing maximum amplitude (R m) of the sunspot cycle.A four-cycle periodicity is roughly shown in the correlation between R m and aa min.The widely accepted Ohl's precursor prediction method often fails due to the prediction error relative to its estimated uncertainty.An accurate prediction depends on the positive variation of the correlation rather than a higher correlation.Previous experiences by using this method indicate that a prediction for the next cycle,R m (24)=80 ± 17,is likely to fail,implying that the sunspot maximum of Cycle 24 may be either smaller than 63 or greater than 97.
基金supported by National Natural Science Foundation of China (Grant No. 60874111)Qing Lan Project of Jiangsu Province and College Science Foundation of Jiangsu Province (Grant No. 07KJD120128)
文摘The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.
文摘Hot Flow Anomalies (HFAs) are phenomena that frequently appear in the vicinity of the Earth's bow shock. We have identified 765 HFA events with Cluster spacecraft data from 2003 to 2009. We study the plasma and magnetic field variations during typical HFAs. Then we study the average structure of HFAs using the superposed epoch method during a 200 s time interval, with the HFA onset time as the epoch time. The results show that HFAs can be classified into four classes based on variations of the dynamic pressure over time, namely "-+" (down-up), "+-" (up-down), "M" (up-down-up) and "W" (up-down-up-down-up), where the letters represent similar shapes with the variation trends of the dynamic pressure. Trends of other parameters are highly related to those of the dynamic pressure with obvious characteristics of the classification. Moreover, statistical results suggest that the number of HFA events varies in years. Compared with the speed of solar wind and sunspot number, the number of HFA events in each year has positive correlation with the former, while it has little relation with the latter. The result of this paper will provide data base for further studies on the mechanisms of the formation, the structural evolution and other relative questions of HFAs.
