Comment on "Westward electric field penetration to the dayside equatorial ionosphere during the main phase of the geomagnetic storm on 22 July 2009" by V.Sreeja et al
Comment on "Westward electric field penetration to the dayside equatorial ionosphere during the main phase of the geomagnetic storm on 22 July 2009" by V.Sreeja et al
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V.Sreeja 等人对“2009 年 7 月 22 日地磁风暴主阶段西向电场穿透赤道电离层”的评论
DOI：
10.1029/2011ja016634
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发表时间：
2011
影响因子：
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通讯作者：
S.Alex
中科院分区：
文献类型：
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作者：
S.Tulasi Ram;M.Yamamoto;H.Liu;B.Veenadhari;S.Alex
[1] Sreeja等人[2011]声称，“2009年7月21日至25日期间发生的地磁风暴是异常的，因为风暴的主阶段是在向北的行星际磁场（IMF）期间发展的”，并且“在风暴的主阶段，向西的电场渗透到白天的赤道电离层”。然而，正如随后讨论的那样，由于他们不正确的IMF Bz数据，所谓的地磁风暴的“异常”特征是不充分的。由于Sreeja等人[2011]提出了诸如2009年7月21日至25日的地磁风暴是异常的，这将对未来的科学研究产生不利影响等严肃的主张，因此非常有必要澄清例如，图1a-1d分别显示了行星际磁场（IMF Bz）、行星际电场（IEF）（IEFy=−vswx Bz）、对称环电流（Sym‐H）指数和赤道电喷流（EEJ）强度的变化。IMF Bz和IEFy的1分钟时间分辨率数据来自大气成分探测器（ACE）。Sym - H指数（1 min值）数据来自京都大学世界地磁数据中心（http://wdc）。kugi。京都的u。ac. jp /)。赤道电喷流的强度（1 min值）是由Tirunelveli （8.7 N地质）的地面磁力计获得的。北纬77.8度。经度和0.6°倾角。纬度)和阿里巴格（18.5北纬）。北纬72.9度。经度和北纬12.9度。纬度)在印度。IMF的Bz和IEFy参数已经被转移，以解释从ACE位置到弓形激波的延迟（http://omniweb）。戈达德宇航中心。美国国家航空航天局。gov / html / HROdocum。html)。从图1可以清楚地看到，IMF Bz从2009年7月22日0154 UT （0724 IST）主相位开始前几个小时开始持续向南移动。然而，与streeja等人不同的是。
[1] Sreeja et al.[2011] have claimed that the “geomagnetic storm that occurred during the period from 21 to 25 July 2009 is anomalous because the storm main phase developed during northward interplanetary magnetic field (IMF)” and “westward electric field penetration to the dayside equatorial ionosphere during the main phase of the storm.” However, as discussed subsequently, the so‐called “anomalous” feature of geomagnetic storm is ill‐fully claimed due to their incorrect IMF Bz data. Since Sreeja et al.[2011] have made serious claims such as the geomagnetic storm of 21–25 July 2009 is anomalous which would have adverse impact on the future scientific investigations, it is highly necessary to clarify.[2] For example, Figures 1a–1d show the variation of interplanetary magnetic field (IMF Bz), interplanetary electric field (IEF)(IEFy=− Vsw× Bz), symmetric ring current (Sym‐H) index and the strength of equatorial electrojet (EEJ), respectively. The 1 min time resolution data of IMF Bz and IEFy are obtained from the Atmospheric Composition Explorer (ACE). The Sym‐H index (1 min values) data is obtained from the World data center for Geomagnetism, Kyoto University (http://wdc. kugi. kyoto‐u. ac. jp/). The strength of equatorial electrojet (1 min values) is obtained from the ground‐based magnetometers at Tirunelveli (8.7 N geog. latitude, 77.8 E geog. longitude and 0.6 N dip. latitude) and Alibagh (18.5 N geog. latitude, 72.9 N geog. longitude and 12.9 N dip. latitude) in India. The IMF Bz and IEFy parameters have been shifted to account for the delay from ACE location to the bow shock (http://omniweb. gsfc. nasa. gov/html/HROdocum. html). It could be clearly seen from Figure 1 that the IMF Bz is southward continuously from several hours before the onset of main phase at 0154 UT (0724 IST) of 22 July 2009. However, unlike Sreeja et al.