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Average features of the interplanetary shock observed with the Global Muon Detector Network

conference contribution
posted on 2023-05-23, 18:23 authored by Kozai, M, Munakata, K, Kato, C, Kuwabara, T, Rockenbach, M, Dal Lago, A, Schuch, NJ, Al Jassar, HK, Sharma, MM, Marcus Duldig, John Humble, Bieber, JW, Evenson, P, Sabbah, I, Tokumaru, M
From three-dimensional spatial density gradient of galactic cosmic rays (GCRs) observed with the Global Muon Detector Network (GMDN), we derive average features of the GCR depleted region behind the IP (interplanetary) shock. We identify 207 IP-shocks that passed the earth based on the geomagnetic storm sudden commencements (SSCs) and extract 50 events that are associated with solar coronal mass ejections (CMEs) in a period between 2006 and 2014. From the first order GCR anisotropy corrected for the solar wind convection and Compton-Getting effect arising from the earth’s orbital motion, we deduce the density gradient on an hourly basis for each event. We then derive the average temporal variation of the density gradient by superposing its variations at the SSC onset timing. We confirm that the density gradient components are clearly enhanced after the shock passage, indicating the existence of GCR depleted region behind the shock which causes the Forbush Decrease in the cosmic ray intensity. The enhancement of the radial gradient shows longer duration when the earth has encountered the western flank of the shock, implying an asymmetric shielding effect of the shock on the GCRs. The longitudinal gradient, on the other hand, shows that the GCR density minimum is located around the longitudinal center behind the shock, which can be ascribed to the centered ejecta driving IP-shock.

History

Publication title

Proceedings of Science

Pagination

1-8

ISSN

1824-8039

Department/School

School of Natural Sciences

Publisher

Scuola Internazionale Superiore di Studi Avanzati (S I S S A),International School of Advanced Studies

Place of publication

Italy

Event title

34th International Cosmic Ray Conference (ICRC 2015)

Event Venue

The Hague, Netherlands

Date of Event (Start Date)

2015-07-30

Date of Event (End Date)

2015-08-06

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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