Introduction

Coronal Mass Ejections (CMEs) -- essential restructuring and large-scale disturbances of the global solar magnetosphere (GSM).
 

Dimmings (transient coronal holes) -- regions of strong depletion in soft X-ray and EUV emission following CMEs; several hours
(e.g., Rust, 1983; Sterling and Hudson, 1997; Hudson and Webb, 1997; Thompson et al., 1998, 1999; Zarro et al., 1999; Hudson and Cliver, 2001).
 

Coronal (EIT) wave -- a bright front propagating before developing dimmings; few hundreds km/s (e.g.,Thompson et al., 1998, 1999; Gopalswamy and Thompson, 2000; Delannee, 2000; Biesecker et al., 2002).
 
 

Previous SOHO studies:

Events of mainly 1997-1998 -- comparatively simple GSM -- more or less isotropic or symmetrical dimmings and coronal waves extending throughout a significant part of the disk (e.g., Thompson et al., 1998, 1999, 2000; Zarro et al., 1999; Klassen et al., 2000; Warmuth et al., 2001).

1997.05.12: Region Fixed difference

-- Twin dimmings (Thompson et al., 1998,1999; Zarro et al., 1999).
-- Dimmings of the transequatorial interconnecting loops (Khan and Hudson, 2000; Pohjolainen et al., 2001).
-- Widely extending dimming patches (Wang et al., 2002).
-- Reflection and refraction of coronal waves under interaction with coronal holes and active regions (Wang, 2000; Ofman and Thompson, 2002).
 
 

Present study:

Events of 2000-2001 -- complicated GSM -- large-scale (global) dimmings have a pronounced anisotropic character and extend along some narrow lengthy structures (channels).

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