Cosmic Ray Modulation Observed by the Princess Sirindhorn Neutron - - PowerPoint PPT Presentation

Introduction Solar Modulation at High Rigidity Cutoff Summary

Cosmic Ray Modulation Observed by the Princess Sirindhorn Neutron Monitor at High Rigidity Cutoff

P.-S. Mangeard,1 J. Clem,1 P. Evenson,1 R. Pyle,2 W. Mitthumsiri ,3 D. Ruffolo,3 A. Sáiz,3 T. Nutaro4

1Bartol Res. Inst. and Dept. of Physics and Astronomy, University of Delaware,

Newark, DE 19716, USA.

2Pyle Consulting Group, Inc., St. Charles, IL 60174, USA.

• 3Dept. of Physics, Fac. of Science, Mahidol University, Bangkok 10400, Thailand.
• 4Dept. of Physics, Fac. of Science, Ubon Ratchathani University, Ubon

Ratchathani 34190, Thailand.

18 July 2017

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 1

Introduction Solar Modulation at High Rigidity Cutoff Summary

Overview

1

Introduction Solar Modulation as Seen by NMs The PSNM Station

2

Solar Modulation at High Rigidity Cutoff Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

3

Summary

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 2

Introduction Solar Modulation at High Rigidity Cutoff Summary Solar Modulation as Seen by NMs The PSNM Station

Solar Modulation as Seen by Neutron Monitors

http://neutronm.bartol.udel.edu/ 1

Flat (qA > 0) or peaked (qA < 0) modulation patterns

2

Spectral crossover of the DRF between periods of qA < 0 and qA > 0 with similar modulation level

3

Linear trend between modulation at high and low cutoff

Moraal et al. (1989) Nuntiyakul et al. (2014) 1 2 3 Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 3

Introduction Solar Modulation at High Rigidity Cutoff Summary Solar Modulation as Seen by NMs The PSNM Station

The PSNM station

BP-28 neutron counter tubes with BF3 At Doi Inthanon, Thailand, ∼2560 m Apparent rigidity cutoff: Pc ∼ 17.3 GV Pmed ∼ 35 GV

www.thaispaceweather.com

Apparent cutoff rigidity (GV)

10 11 12 13 14 15 16 17 18 19

qA+ qA- qA+ qA- qA+ qA- qA+

Year

1950 1960 1970 1980 1990 2000 2010

AHME BUEN CHAC CORD DAEJ DARW DOIN ESOI FUKU HALE HALE HUAN KAMP KDIK KULA LAEP MAKA MINA MORI NORI PUTR RIOD SEOU SNTI TIBT TKYO

AHME: Ahmedabad BUEN: Buenos Aeres CHAC: Chacaltaya CORD: Cordoba DAEJ: Daejon DARW: Darwin DOIN: Doi Inthanon ESOI: ESOI-Tau (Israel) FUKU: Fukushima HALE: Haleakala HUAN: Huancayo KAMP: Kampala KDIK: Kodaikanal KULA: Kula Hawaii LAEP: Lae Papua MAKA: Makapuu Point MINA: Mina Aguilar MORI: Morioka NORI: Mount Norikura PUTR: Putre Incas RIOD: Rio de Janeiro SEOU: Seoul SNTI: Santiago TIBT: Tibet TKYO: Tokyo

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 4

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Observation by PSNM

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Count rates averaged per Carrington rotation. The variations of the rigidity cutoff are assumed negligible. Tropical climate: correction for variations of the water vapor pressure at the surface. Grey: All data. Black: Main Forbush decreases were removed. Note dips of 1-2 months, even with Forbush decreases removed.

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 5

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Observation by PSNM

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Total Sunspot Number WDC-SILSO Mean 50 100 150 200

Data V2.0 from http://www.sidc.be/silso/datafiles Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 6

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Observation by PSNM

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

T) µ magnetic field ( WSO polar 50 − 50

Bs Bn Ba=(Bn-Bs)/2

Data from http://wso.stanford.edu/Polar.html Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 6

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Observation by PSNM

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

1 Solar polarity qA < 0 with low solar activity (RED) 2 4-year plateau with full recoveries (BROWN) 3 Fast decrease of the count rate: ∼50% of the total

modulation (GREEN). Synchronous with the increase of e+/e− measurements from PAMELA (Adriani et al. (2016))

4 Solar polarity qA > 0 (BLUE) Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 6

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With McMurdo Data (1)

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

McMurdo count rate (Hz) 250 260 270 280 290 300

Distinct pattern during the period of high solar activity

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 7

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With McMurdo Data (2)

McMurdo count rate (Hz)

250 260 270 280 290 300

Doi Inthanon count rate (Hz)

605 610 615 620 625

2007 Dec 9 to 2010 Apr 22 2010 Apr 22 to 2014 Feb 2 2014 Feb 2 to 2014 Nov 11 2014 Nov 11 to 2017 Jan 7

qA<0 4-year plateau Fast drop at DI qA>0 a

Linear trends during low solar

• activity. Is there a change of

slope after the solar polarity reversal? Spectral hysteresis is observed The fast decrease at DI is actually observed at McMurdo... Loss of linearity for ∼ 4 years. This was only during ∼1 year (∼2000) for the previous solar maximum (Nuntiyakul et al. (2014)).

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 8

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With McMurdo Data (3)

McMurdo count rate (Hz)

250 260 270 280 290 300

Doi Inthanon count rate (Hz)

605 610 615 620 625

qA>0 R=0.983 s=0.49+/-0.02 qA<0 R=0.948 s=0.58+/-0.04 qA<0, rise R=1.000 s=0.60+/-0.05 qA<0, fall R=1.000 s=0.61+/-0.05

b

Scatter plot for low solar activity only The linear trend between count rates of NMs at different cutoff is now observed at ∼17 GV The change of slope after the solar magnetic polarity reversal confirms the observation from the latitude surveys (Nuntiyakul et al. (2014))

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 9

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With McMurdo Data (3)

McMurdo count rate (Hz)

250 260 270 280 290 300

Doi Inthanon count rate (Hz)

605 610 615 620 625

qA>0 R=0.983 s=0.49+/-0.02 qA<0 R=0.948 s=0.58+/-0.04 qA<0, rise R=1.000 s=0.60+/-0.05 qA<0, fall R=1.000 s=0.61+/-0.05

b

Scatter plot for low solar activity only The linear trend between count rates of NMs at different cutoff is now observed at ∼17 GV The change of slope after the solar magnetic polarity reversal confirms the observation from the latitude surveys (Nuntiyakul et al. (2014)) What about the crossover? We need more NMs at different rigidity cutoffs

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 9

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Inadequacy of Modulation Parameter Derived From Low-Cutoff NM Data

Modulations from the NMs at Almaty, McMurdo, and Newark using the method presented in Ghelfi et al. (2016, 2017)

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Doi Inthanon count rate (Hz) 590 595 600 605 610 615 620 625 Observation =6.7 GV

c

• P

Almaty

Φ MC - =2.0 GV

c

• P

Newark

Φ MC - =0.3 GV

c

• P

McMurdo

Φ MC -

A single modulation parameter doesn’t allow one to reproduce the variations over the whole period at all cutoffs. Observed modulation at 6.7 GV is much more similar to that

• bserved at DI than that at McMurdo

Compatible with a crossover at 5-6 GV

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 10

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With Tilt Angle From WSO

A delay of two Carrington rotations is applied.

) ° Tilt angle ( 10 20 30 40 50 60 70 Doi Inthanon count rate (Hz) 605 610 615 620 625

2007 Dec 9 to 2009 Dec 7 2009 Dec 7 to 2011 Mar 16 2011 Mar 16 to 2014 Feb 11 2014 Feb 11 to 2015 Apr 1 2014 Apr 1 to 2017 Jan 7 a

) ° Tilt angle ( 10 20 30 40 50 60 70 McMurdo count rate (Hz) 250 260 270 280 290 300

b

At qA < 0, low tilt angles (<∼40◦) were well correlated with variations at both stations as expected from drift calculations. About 4 years of data with very high tilt angle (>∼65◦) We have a 4-year plateau at DI with the loss of linearity...

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 11

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Loss of Linearity at Very High Tilt Angle

http://wso.stanford.edu/gifs/Tilts.gif

∼1 year near 2000: loss of linearity in the latitude surveys ∼4 years 2011-2014: loss of linearity between DI and McMurdo Could be related to duration at high tilt angle, > 65◦.

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 12

Introduction Solar Modulation at High Rigidity Cutoff Summary Observation by PSNM Comparison With Other NM Data Comparison With Heliospheric Measurements

Comparison With the Interplanetary Magnetic Field (ACE)

ACE-MAG - IMF B (nT) 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 Doi Inthanon Count rate (Hz) 605 610 615 620 625

2007 Dec 9 to 2010 Apr 22 2010 Apr 22 to 2014 Feb 2 2014 Feb 2 to 2014 Nov 11 2014 Nov 11 to 2017 Jan 7 a

ACE-MAG - IMF B (nT) 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 McMurdo Count rate (Hz) 250 260 270 280 290 300

b

Variations at DI are very well correlated with the IMF at qA < 0 with a very tilted HCS and at qA > 0. Variations at McMurdo are correlated with the IMF at qA > 0. 4 year plateau at DI is consistent with an increase in diffusion at high rigidity that short-circuits the effects of drifts and HCS during qA < 0.

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 13

Introduction Solar Modulation at High Rigidity Cutoff Summary

Summary

Observations at Doi Inthanon confirm the results from the latitude surveys and extend them to higher cutoff rigidity Low tilt angle: Linear relation between count rates of NMs at different cutoff.

Dependence of the slope on solar magnetic polarity Compatible with the spectral crossover at 5-6 GV.

High tilt angle: Distinct modulation patterns at high and low rigidity cutoff

The 4-year plateau and count rate minimum at DI can be explained by the variations of the IMF

Proceeding ICRC2017_036 “Tracking cosmic-ray spectral variations with neutron monitor time-delay measurements at high cutoff rigidity during 2007-2017”, Banglieng et al., Proceeding ICRC2017_025

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 14

Introduction Solar Modulation at High Rigidity Cutoff Summary

BACKUP

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 15

Introduction Solar Modulation at High Rigidity Cutoff Summary

Correction for water vapor pressure

620 610 600 590 580 Pressure-corrected Doi Inthanon count rate (Hz) 16 14 12 10 8 6 4 2 Surface water vapor pressure (hPa)

CWVcor = CPcor 1 − aEw,0 1 − aEw (1) a = (2.05 ± 0.19) × 10−4 hPa−1 Dots: pressure-corrected count rate at DI, averaged in 6-h intervals, versus water vapor pressure, Ew, interpolated from GDAS data; circles: mean values of count rate for 1-hPa intervals in Ew; line: linear fit to mean values. Ew,0 = 6.3 hPa is chosen as in Ruffolo et al.(2016).

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 16

Introduction Solar Modulation at High Rigidity Cutoff Summary

Comparison With Tilt Angle From WSO

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

) ° WSO HCS tilt angle ( 20 40 60 80

Data from http://wso.stanford.edu/Tilts.html Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 17

Introduction Solar Modulation at High Rigidity Cutoff Summary

Comparison With the Solar Wind (ACE)

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

ACE solar wind speed (km/s) 300 350 400 450 500 550

Data from http://www.srl.caltech.edu/ACE/ASC/level2/lvl2DATA_SWEPAM.html Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 18

Introduction Solar Modulation at High Rigidity Cutoff Summary

Comparison With the Solar Wind (ACE) (2)

ACE-SWEPAM - SW speed (km/s) 300 350 400 450 500 550 Doi Inthanon Count rate (Hz) 605 610 615 620 625

2007 Dec 9 to 2010 Apr 22 2010 Apr 22 to 2014 Feb 2 2014 Feb 2 to 2014 Nov 11 2014 Nov 11 to 2017 Jan 7 a

ACE-SWEPAM - SW speed (km/s) 300 350 400 450 500 550 McMurdo Count rate (Hz) 260 270 280 290

c

At qA < 0 with low solar activity, variations in the count rates are well correlated with the solar wind. At qA > 0 no correlation is observed. During the transition, the correlation with variations at DI is low

Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 19

Introduction Solar Modulation at High Rigidity Cutoff Summary

Comparison With the Interplanetary Magnetic Field (ACE)

Polarity reversal

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Doi Inthanon count rate (Hz) 600 605 610 615 620 625

Solar minimum maximum min?

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

magnetic field (nT) ACE interplanetary 4 6 8

Data from http://www.srl.caltech.edu/ACE/ASC/level2/lvl2DATA_MAG.html Pierre-Simon Mangeard (University of Delaware) 35th ICRC, 10-20 July 2017, Busan, South Korea 20