Solar Activity Dependence of Ionosphere Ion Upflow in the Polar Topside
-
摘要: 利用第23太阳活动周DMSP F12,F13和F15卫星数据,分别对南北半球极区顶部电离层离子上行的太阳活动依赖性进行了研究.结果表明,南北半球上行事件对太阳活动的响应特征基本一致,即高(低)太阳活动时,离子上行通量以及上行数密度较大(小),但是上行速度及上行发生率较低(高).以南半球高纬为例,计算得到离子上行通量、数密度、速度及发生率在高低太阳活动条件下的比值分别约为2.26,3.35,0.71,0.51.对离子上行太阳活动依赖性的可能原因进行了分析.不同太阳活动水平下,光致电离及高能粒子沉降的差异会导致电离层离子密度的不同,而电离层离子密度的变化会改变离子elax-elax中性大气之间的碰撞频率,这是影响离子上行发生率的一个重要原因.Abstract: The influence of solar activity on ionosphere ion upflow was studied, over the northern and southern hemispheric polar topside. The observations were obtained from the Defense Meteorological Satellite between 1995 and 2005. Results show that the response characteristics of upflow events on solar activity are roughly consistent for the two hemispheres, that is, ion upflow fluxes and ion densities are generally larger during high solar activity than those during low solar activity, but ion vertical velocities and upflow occurrence rates show an opposite variation trends, i.e., they are higher and more frequently seen under the conditions of low solar activity, respectively. Besides, we further calculated the mean value of upflow parameters in the southern hemisphere. The ratios of them under high and low solar activity conditions are about 2.26, 3.35, 0.71 and 0.51. Furthermore, the results also show that it is the ion densities instead of ion vertical velocities that have profound effect on the upflow fluxes. The causes of such a dependence is briefly analyzed. Under different levels of solar activity, ionosphere ion densities are different because of the variations of ionization rates and ion-neutral collision frequencies. The collision frequency between ion and neutral atmosphere is closely related to the ion density. Therefore, the ion upflow occurrence rate in the polar topside ionosphere depends on the level of solar activity.
-
Key words:
- Ion upflow /
- Solar activity /
- Polar ionosphere /
- Ionization rate /
- Collision frequency
-
[1] SHELLEY E G, JOHNSON R G, SHARP R D. Satellite observations of energetic heavy ions during a geomagnetic storm[J]. J. Geophys. Res., 1972, 77(31):6104-6110 [2] ANDRÉ M, NORQVIST P, ANDERSSON L, et al. Ion energization mechanisms at 1700km in the auroral region[J]. J. Geophys. Res., 1998, 103:4199-4222 [3] ANDRÉ M, YAU A W. Theories and observations of ion energization and outflow in the high latitude magnetosphere[J]. Space Sci. Rev., 1997, 80:27-48 [4] YAU A W, ANDRÉ M. Sources of ion outflow in the high latitude ionosphere[J]. Space Sci. Rev., 1997, 80 (1/2):1-25 [5] ZHAO Kai, JIANG Yong, DING Liuguan, et al. Statistical analysis of outflow ionospheric O+ on the declining phase of solar cycle 23 using Fast observations[J]. Planet. Space Sci., 2014, 101:170-180 [6] ZHAO Kai, JIANG Yong, MEN Kepei, et al. Interhemispheric comparisons of ionospheric upflow H+ at various geomagnetic activity levels using fast observations[J]. Chin. J. Geophys., 2014, 57(11):3715-3728(赵凯, 蒋勇, 门可佩, 等. 不同地磁活动水平下电离层H+上行的半球对比研究[J]. 地球物理学报, 2014, 57(11):3715-3728) [7] FOSTER C, LESTER M, DAVIES J A. A statistical study of diurnal, seasonal and solar cycle variations of F-region and topside auroral upflows observed by EISCAT between 1984 and 1996[J]. Ann. Geophys., 1998, 16:1144-1158 [8] COLEY W R, HEELIS R A, HAIRSTON M R. Characteristics of high-latitude vertical plasma flow from the Defense Meteorological Satellite Program[J]. J. Geophys. Res., 2006, 111:A11314. doi: 10.1029/2005JA011553 [9] OGAWA Y, BUCHERT S C, SAKURAI A, et al. Solar activity dependence of ion upflow in the polar ionosphere observed with the European Incoherent Scatter (EISCAT) Tromsø UHF radar[J]. J. Geophys. Res., 2010, 115:A07310. DOI: 10.1029/2009JA014766 [10] ABE T, YAU A W, WATANABE S, et al. Long-term variation of the polar wind velocity and its implication for the ion acceleration process:Akebono/suprathermal ion mass spectrometer Observations[J]. J. Geophys. Res., 2004, 109:A09305. DOI: 10.1029/2003JA010223 [11] XU Sheng, ZHANG Beichen, LIU Ruiyuan. Comparative studies on solar activity variations of NmF2 at the Arctic and Antarctic Stations[J]. Chin. J. Geophys., 2014, 57(11):3502-3511(徐盛, 张北辰, 刘瑞源. 极区电离层F2层峰值电子浓度对太阳活动依赖性的共轭研究[J].地球物理学报, 2014, 57(11):3502-3511) [12] HINTEREGGER H E, BEDO D E, MANSON J E. The EUV spectrophotometer on atmosphere explorer[J]. Radio Sci., 1973, 8(4):349-359 [13] RICHARDS P G, FENNELLY J A, TORR D G. EUVAC:A solar EUV flux model for aeronomic calculations[J]. J. Geophys. Res., 1994, 99(A5):8981-8992 [14] LIU L B, WAN W X, NING B Q, et al. Solar activity variations of the ionospheric peak electron density[J]. J. Geophys. Res., 2006, 111:A08304. DOI:10. 1029/2006JA011598 [15] LIU L B, WAN W X, CHEN Y D, et al. Solar activity effects of the ionosphere:A brief review[J]. Chin. Sci. Bull., 2011, 56:1202-1211 [16] ZHOU Kangjun, CAI Hongtao, CHENG Lijun, et al. Feature of ion up-flow at high-latitude topside ionosphere during geomagnetic storms from the Defense Meteorological Satellite Program[J]. Chin. J. Geophys., 2014, 57(11):3541-3550(周康俊, 蔡红涛, 程力君, 等. 磁暴期间高纬顶部电离层离子上行特征DMSP卫星观测[J]. 地球物理学报, 2014, 57(11):3541-3550) [17] SCHUNK R W, NAGY A F. Ionospheres:Physics, Plasma Physics, and Chemistry[M]. New York:Cambridge University Press, 2009 [18] NIU Jun, FANG Hanxian, WENG Libin. Correlation between solar activity and thermospheric density[J]. Chin. J. Space Sci., 2014, 34(1):73-80(牛俊, 方涵先, 翁利斌. 太阳活动与热层大气密度的相关性研究[J]. 空间科学学报, 2014, 34 (1):73-80) [19] WENG Libin, FANG Hanxian, JI Chuanhua, et al. Comparison between the CHAMP/STAR derived thermospheric density and the NRLMSISE-00 model[J]. Chin. J. Space Sci., 2012, 32(5):713-719(翁利斌, 方涵先, 季春华, 张阳. 基于卫星加速度数据反演的热层大气密度与NRLMSISE-00模式结果的比较研究[J]. 空间科学学报, 2012, 32(5):713-719) [20] CHEN Xuxing, HU Xiong, XIAO Cunying, et al. Comparison of the thermospheric densities between GRACE/CHAMP satellite data and NRLMSISE-00 MODEL[J]. Chin. J. Space Sci., 2013, 33(5):509-517(陈旭杏, 胡雄, 肖存英, 等. NRLMSISE-00大气模型与GRACE和CHAMP卫星大气密度数据的对比分析[J]. 空间科学学报, 2013, 33(5):509-517)
点击查看大图
计量
- 文章访问数: 1159
- HTML全文浏览量: 72
- PDF下载量: 1416
- 被引次数: 0