[1] According to the loading-unloading substorm scenario, the magnetic flux, stored in the magnetotail during the substorm growth phase,is dissipated in the course of the expansion phase. However so far only separate estimates of both accumulated and dissipated flux values were made due to the lack of methods to calculate those quantities, doing their direct comparison impossible. First, we analyzed the magnetotail magnetic flux at substorm onset as a function of solar wind parameters to show that the tail magnetic flux, stored during the growth phase (DF T ), depends mainly (CC = 0.95) on the merging electric field E m = V SW B t sin 3 q/2. It implies the lack of threshold magnetic flux at substorm onset. Also, the magnetic flux through the auroral bulge at substorm maximum (

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Abstract. Using data from WIND spacecraft, we investigated the difference in substorm bulge development during different types of solar wind flow: solar wind recurrent streams (RS), corotating interaction regions (CIR), magnetic clouds (MC), and the region of interaction of magnetic clouds with undisturbed solar wind (Sheath). The RS/CIR and MC/Sheath structures were examined for the periods December 1996-July 1997; January 2000-December 2000; October 2001. All available auroral substorms observed by the Ultra Violet Imager onboard the Polar spacecraft during these periods were studied. It is shown that the largest latitudinal and longitudinal sizes of the auroral bulge expansions are during CIR and Sheath intervals. We found a difference in auroral bulge parameters for MC-and RS-associated substorms. In contrast to substorms associated with RS, the latitudinal size of the auroral bulge during MC is smaller, but longitudinal size is larger. As consequence, the ratio between longitudinal and latitudinal sizes for MC-associated substorms is also larger. We suggest that the latter feature is explained by different configuration of the near-Earth magnetotail during RS and MC.

All substorm disturbances observed in polar latitudes can be divided into two types: polar, which are observable at geomagnetic latitudes higher than 70° in the absence of substorms below 70°, and high lat itude substorms, which travel from auroral (<70°) to polar (>70°) geomagnetic latitudes. The aim of this study is to compare conditions in the IMF and solar wind, under which these two types of substorms are observable on the basis of data from meridional chain of magnetometers IMAGE and OMNI database for 1995, 2000, and 2006-2011 In total, 105 polar and 55 high latitude substorms were studied. It is shown that polar sub storms are observable at a low velocity of solar wind after propagation of a high speed recurrent stream during the late recovery phase of a magnetic storm. High latitude substorms, in contrast, are observable with a high velocity of solar wind, increased values of the Bz component of the IMF, the Ey component of the electric field, and solar wind temperature and pressure, when a high speed recurrent stream passes by the Earth.