From ahm@hao.ucar.edu Thu Jun 11 07:39:31 1998 Return-Path: Received: from isass0.solar.isas.ac.jp by isass6.solar.isas.ac.jp (4.1/SMI-4.1) id AA28640; Thu, 11 Jun 98 07:39:27 JST Received: from jabba.hao.ucar.edu by isass0.solar.isas.ac.jp (5.65v4.0/1.1.8.2/01Feb95-0732AM) id AA28955; Thu, 11 Jun 1998 07:39:32 +0900 Received: from voyager.hao.ucar.edu (voyager.hao.ucar.edu [128.117.16.58]) by jabba.hao.ucar.edu (8.9.0/8.9.0) with ESMTP id QAA21468; Wed, 10 Jun 1998 16:38:36 -0600 (MDT) Received: (from ahm@localhost) by voyager.hao.ucar.edu (8.8.5/8.8.5) id WAA13576; Wed, 10 Jun 1998 22:38:35 GMT From: "Alan McAllister" Message-Id: <9806101638.ZM13574@voyager> Date: Wed, 10 Jun 1998 16:38:30 -0600 In-Reply-To: CROOKER@buasta.bu.edu "have referred Hugh to you" (Jun 10, 4:17am) References: <01IY23R4PSG80001NP@buasta.bu.edu> X-Mailer: Z-Mail (3.2.3 08feb96 MediaMail) To: CROOKER@buasta.bu.edu Subject: Preliminary analysis/prediction Cc: nfox@pop600.gsfc.nasa.gov, ahm@voyager.hao.ucar.edu, hudson@isass0.solar.isas.ac.jp, sfm@primenet.com, vpizzo@sec.noaa.gov Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Status: R Hello all, A quick look at available synoptic data yields the following: %Prediction of possible cloud helicity from halo CME launched on June 8, 1998. Observations: The solar event was associated with a sunspot (AR8232) crossing central meridian about 20 degrees south of the equator. The highest coronal fields have the usual southward component for the rise of an odd numbered solar cycle. The underlying neutral line is only 30 degrees from NS as it passes through the active region, rotating closer to EW as it extends to the SE towards the polar crown. It is closer to 45 degrees as it passes out of the southern end of the AR. EIT movie located just north of the AR shows opening of coronal loops after 16:00 to roughly 16:30. The Yohkoh data shows flaring in the AR in the 16:49 frame (not there at 15:58), which corresponds to the flare Hugh refers to at 16:03. This has died down by 18:26. There appears to be a second more coronally disruptive event between 18:51 and 00:04, at which time the larger arcades north and south of the AR are much expanded, and in the process of further expansion. There is a large filament on the polar crown to the SE, which is unchanged between 14:04 and 19:56 (Holloman Ha), although a small filament just south of the active region appears to have vanished. The large filament may fade out between 21:06 (KP He1 10830) and gone at 00:00 (Big Bear Ha)? This indicates a large scale eruption over a neutral line tilted SE-NW at roughly 45 degrees. The coronal arcades are right skewed, as is predominent in the southern hemisphere, and suggest that the filament will be sinistral. However as this is a polar crown it should be checked with the Ha images. The axial component along the neutral line is pointing SE. Comments: It appears from the SXT and HA data that this may have been a multi-part event, with a larger region opening up about 3-4 hours after the initial flare. Mauna Loa shows that the arcade leading towards the SE limb is associated with a full white light streamer. If this is part of the global solar wind structure, and IP current sheet, then any flux rope may not be strongly deformed in transit. [ This assumption needs to be tested.] **** Predicted possible IP cloud topology **** There may be leading southward fields, followed by a highly inclined (~ 45 degrees) flux rope. Its leading fields should have a slight southward component, strengthening torwards the axis, where the axial field is SE. This configuration can be expected to produce enhanced geomagnetic activity. Several things should be checked: Sara, can you check the chirality of the large polar crown filament? Nancy, is there a good way to quickly check on sector structure, boundaries, etc? *** Any comments, feedback, additions, or corrections can be sent to Alan McAllister at ahm@hao.ucar.edu. --