Forbush decreases at The Princess Sirindhorn neutron monitor and the leader fraction
16
Issued Date
2020
Copyright Date
2020
Resource Type
Language
eng
File Type
application/pdf
No. of Pages/File Size
xvi, 85 leaves : ill.
Access Rights
open access
Rights
ผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้า
Rights Holder(s)
Mahidol University
Bibliographic Citation
Thesis (Ph.D. (Physics))--Mahidol University, 2020
Suggested Citation
Chanoknan Banglieng Forbush decreases at The Princess Sirindhorn neutron monitor and the leader fraction. Thesis (Ph.D. (Physics))--Mahidol University, 2020. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/92263
Title
Forbush decreases at The Princess Sirindhorn neutron monitor and the leader fraction
Author(s)
Abstract
The Princess Sirindron Neutron Monitor (PSNM) with the world's highest geomagnetic cutoff rigidity ~17 GV, was the first fixed station using the specialized electronics to collect time delay histograms for statistically estimating the leader fraction L. Our analysis data period, during 2007 Dec - 2018 Apr 19, covered almost a full 11-year solar cycle. After correcting for pressure and precipitable water vapor in both the leader fraction L as a proxy of the GCR spectral index and count rate C as a measurement of GCR flux above the cutoff rigidity at PSNM's location, we find that L is roughly correlated with C, but also exhibits hysteresis that indicates a change in spectral shape after the change in solar magnetic polarity. These methods enhance the high-precision GCR spectral information from the worldwide NM network and extend it to higher rigidity. A Forbush decrease (FD) is the decrease in count rate as observed by a neutron monitor associated with a solar storm (CME) and/or its shock. The viewing direction of PSNM sometimes observed the pre-Forbush decrease level in events defined as diurnal dips (DDs). We developed criteria to select decreases observed by PSNM as DDs or FDs. Our criteria found 16 DDs and 20 FDs.
Description
Physics (Mahidol University 2020)
Degree Name
Doctor of Philosophy
Degree Level
Doctoral Degree
Degree Department
Faculty of Science
Degree Discipline
Physics
Degree Grantor(s)
Mahidol University