Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction. However, the indices suffer from various uncertainties, which limit their application and ev...Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction. However, the indices suffer from various uncertainties, which limit their application and even mislead to incorrect conclu-sion. In this paper we analyze three most popular indices, Kp, AE and Dst. Three categories of uncertainties in magnetic indices are discussed: "data uncertainty" originating from inadequate data processing, "station uncertainty" caused by in-complete station covering, and "physical uncertainty" stemming from unclear physical mechanism. A comparison between magnetic disturbances and related indices indicate that the residual Sq will cause an uncertainty of 1―2 in K meas-urement, the uncertainty in saturated AE is as much as 50%, and the uncertainty in Dst index caused by the partial ring currents is about a half of the partial ring cur-rent.展开更多
We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmo...We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmosphere.Our consideration of mutual correlations between the solar indices is based on the study of relationships between them in the period from 1950 to 1990.This period of time,covering activity cycles 19–22,is characterized by relatively stable relations between the indices.We investigate the normalized variations of these indices in recent time in relation to their values which were calculated by considering radiation from the Sun in the radio range at a wavelength of 10.7 cm(F10.7) in 1950–1990.The analysis of time series,representing variations of the normalized AI(AIFF) in solar cycles 23–24,shows different trends exist for different indices in terms of their long-term behavior.We assume that variations of normalized International Sunspot Number(SSN),F530.3 and Flare Index,which have shown sharp decreases in the last 40 years,are possibly associated with a decrease in the intensity of large-scale magnetic fields in the photosphere(SSN) and in the corona(the coronal index and the Flare Index).展开更多
基金the National Natural Science Foundation of China (Grant No. 40436016)the National Basic Research Program of China ("973") (Grant No. 2006CB806305)the KIP Pilot Project of the Chinese Academy of Sciences (Grant No. kzcx3-sw-144)
文摘Magnetic activity indices are widely used in theoretical studies of solar-terrestrial coupling and space weather prediction. However, the indices suffer from various uncertainties, which limit their application and even mislead to incorrect conclu-sion. In this paper we analyze three most popular indices, Kp, AE and Dst. Three categories of uncertainties in magnetic indices are discussed: "data uncertainty" originating from inadequate data processing, "station uncertainty" caused by in-complete station covering, and "physical uncertainty" stemming from unclear physical mechanism. A comparison between magnetic disturbances and related indices indicate that the residual Sq will cause an uncertainty of 1―2 in K meas-urement, the uncertainty in saturated AE is as much as 50%, and the uncertainty in Dst index caused by the partial ring currents is about a half of the partial ring cur-rent.
文摘We analyze long-term variations of several solar activity indices(AIs) that have been measured over the last 40 years.With this goal,we study the AIs that characterize the fluxes from different areas in the solar atmosphere.Our consideration of mutual correlations between the solar indices is based on the study of relationships between them in the period from 1950 to 1990.This period of time,covering activity cycles 19–22,is characterized by relatively stable relations between the indices.We investigate the normalized variations of these indices in recent time in relation to their values which were calculated by considering radiation from the Sun in the radio range at a wavelength of 10.7 cm(F10.7) in 1950–1990.The analysis of time series,representing variations of the normalized AI(AIFF) in solar cycles 23–24,shows different trends exist for different indices in terms of their long-term behavior.We assume that variations of normalized International Sunspot Number(SSN),F530.3 and Flare Index,which have shown sharp decreases in the last 40 years,are possibly associated with a decrease in the intensity of large-scale magnetic fields in the photosphere(SSN) and in the corona(the coronal index and the Flare Index).
