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# ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

## Relation of Forbush decrease with interplanetary magnetic fields.

Aug 4, 2015, 4:00 PM
1h
Theater Foyer (World Forum)

### Theater Foyer

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 3
Poster contribution SH-EX

### Speaker

ARUNBABU Kollamparambil Paul (Tata Institute of Fundamental Research, Mumbai, India)

### Description

The relation between the Forbush decreases (FDs) and near-Earth interplanetary magnetic field (IMF) enhancements associated with the solar coronal mass ejections (CMEs) is studied. We have used data from GRAPES-3 tracking muon telescope to identify the Forbush decrease events. We have chosen events that are having a reasonably clean profile, and magnitude $>$ 0.25 %. We have used IMF data from ACE/WIND spacecrafts to investigate how closely the FD profile follow the IMF enhancements. We found that the enhancement of magnetic field responsible for the FD takes place mainly in the sheath region and also the MHD turbulence level get enhanced in this region. We found that the FD profile looks remarkably similar to that of IMF enhancement, yielding good correlation with a time lag. The FD profile lags behind the IMF by few hours. This observed lag corresponds to the time taken by high energy protons to diffuse into the magnetic field enhancement through cross-field diffusion.
Registration number following "ICRC2015-I/" 37 -- not specified --

### Primary author

ARUNBABU Kollamparambil Paul (Tata Institute of Fundamental Research, Mumbai, India)

### Co-authors

Dr A. Oshima (College of Engineering, Chubu University, Kasugai, Aichi, Japan) Prof. H. M. Antia (Tata Institute of Fundamental Research, Mumbai. India) PRAVATA MOHANTY (Tata Institute of Fundamental Research, Mumbai, India) Dr Prasad Subramanian (Indian Institute of Science Education and Research, Pune, India) Prof. S. Kawakami (Graduate School of Science, Osaka City University, Osaka, Japan) Shashi Dugad (Tata Inst. of Fundamental Research (IN)) Prof. Sunil K. GUPTA (Tata Institute of Fundamental Research, Mumbai. India) Prof. Y. Hayashi (Graduate School of Science, Osaka City University, Osaka, Japan)