Variations of microwave emission and mdi topology in the active region NOAA 10030 before and during the power flare series

Abstract

The pre-flaring activity of the X3.0 (GOES class) flare that occurred in active region (AR) NOAA 10030 on 2002 July 15 is analyzed. We concentrate on the microwave (MW) emission and MDI topology in AR during some days before the X3 flare. Daily solar multi-wave observations with the RATAN-600 radio telescope in the range of 1.8–5.0 cm have been used. The following features in MW emission of AR have been detected in pre-flare period: (1) We have a new evidence of the MW “peculiar” source which has appeared 1 day before the X3 flare as a result of formation of δ-configuration in the central part of sunspot group. Such “peculiar” sources have been observed earlier with RATAN-600 in many active regions as precursors of high flare activity. (2) The most intensive local MW sources registered in the regions between the main sunspots coincide with the places of greatest values of the emission measure calculated by two lines of UV emission (SOHO/EIT). (3) The MW emission associated with the leading sunspot in AR considerably decreased (disappeared) 2 days before the X3.0 flare probably due to the changing of height of the emitting region. A topological method for detecting in AR a new emergence of magnetic flux using successive SOHO/MDI images of the solar disk is proposed. It was found that a number of disconnected components increases directly before the series of power flares (in particular, before the event on 2002 July 15) or accompanies this process.