J/ApJ/950/89 >40MeV proton intensities from 43yr near Earth obs. (Lario+, 2023)
High-energy (>40MeV) proton intensity enhancements associated with the passage
of interplanetary shocks at 1 au.
Lario D., Richardson I.G., Aran A., Wijsen N.
<Astrophys. J., 950, 89 (2023)>
=2023ApJ...950...89L 2023ApJ...950...89L
ADC_Keywords: Sun; Solar system; Gamma rays
Keywords: Solar energetic particles ; Interplanetary shocks ;
Interplanetary particle acceleration
Abstract:
We analyze periods with elevated >40MeV proton intensities observed
near Earth over a time span of 43yr (1973-2016) that coincide with the
passage of interplanetary (IP) shocks. Typically, elevated proton
intensities result from large solar energetic particle (SEP) events.
The IP shocks observed during these elevated-intensity periods may or
may not be related to the origin of the SEP events. By choosing those
cases when the shocks can be confidently associated with the solar
eruption that generated the SEP event, we analyze the components of
these SEP events that are localized in the vicinity of the shock
(so-called "energetic storm particles", ESPs), focusing on those
events where the ESP component exceeds 40MeV. We examine the
interdependence of these high-energy ESPs with (i) the properties of
the solar eruptions that generated the shocks and the SEP events, and
(ii) the parameters of the shocks at their arrival at 1au. The solar
eruptions at the origin of the shocks producing >40MeV proton ESP
intensity enhancements are within ±50° longitude of central
meridian and are associated with fast coronal mass ejections
(plane-of-sky speeds ≳1000km/s). The ESP events with the largest
>40MeV proton intensity increases tend to occur when there are
structures such as intervening IP coronal mass ejections and other
unrelated shocks present in the solar wind through which the shock is
propagating. Among the various local shock parameters considered, only
the shock speed shows a certain degree of correlation with the
observed ESP intensity increase.
Description:
An initial identification of the periods with elevated >40MeV proton
intensities was made using data from the Goddard Medium Energy (GME)
instrument on board the Interplanetary (IP) Monitoring Platform-8
(IMP-8) covering the time interval from 1973 November to 2001 October.
In particular, we selected periods when the 42.9-51.0MeV proton
intensities were above the instrumental background. In order to extend
the analysis from 2001 October to 2006 December, we also checked for
periods when the 40.5-53.5MeV proton energy channel of the Energetic
and Relativistic Nuclei and Electron (ERNE) instrument on board the
Solar and Heliospheric Observatory (SOHO) was elevated above the
intensity instrumental background.
We decided to combine the IMP-8/GME and SOHO/ERNE data with the
Reference Data Set (RDS) v2.0 of the Solar Energetic Particle
Environment Modeling (SEPEM) project (Jiggens+ 2018JSWSC...8A..31J 2018JSWSC...8A..31J;
http://sepem.eu/).
Starting in solar cycle 23, the continuous data from the Advanced
Composition Explorer (ACE) and the Wind spacecraft (when in the solar
wind) were used to check for the passage of IP shocks. In particular,
we inspected data from the Solar Wind Electron Proton Alpha Monitor
(SWEPAM) and the Magnetometer Field Experiment (MAG) on board ACE, and
the Solar Wind Experiment (SWE) and the Magnetic Field Investigation
on board Wind, together with the Proton Monitor of the Mass
Time-of-flight (MTOF) sensor of the Charge, Element, and Isotope
Analysis System (CELIAS) on SOHO.
We also checked for the passage of IP shocks by inspecting catalogs of
IP shocks such as the Database of Heliospheric Shock Waves generated
by the University of Helsinki (Kilpua+ 2015JGRA..120.4112K 2015JGRA..120.4112K),
the list of shocks observed by the Proton Monitor of SOHO/CELIAS/MTOF,
the list of ACE disturbances at
www.ssg.sr.unh.edu/mag/ace/ACElists/obs_list.html, and the
Harvard-Smithsonian Center for Astrophysics (CfA) Interplanetary
Shock Database at www.cfa.harvard.edu/shocks/.
See Section 2 for further information.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 138 191 *Selected shock passages occurring during enhanced
∼40MeV proton intensities
table2.dat 129 190 Intensities measured during the passage of the
shocks listed in Table 1
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Note on table1.dat: Note that the shock parameters are not available when
there are no solar wind observations, e.g. from ACE during intense
particle events, during spacecraft data gaps, or when IMP-8 was within
the Earth's magnetosphere, especially during solar cycles 21 and 22.
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See also:
J/A+A/440/373 : Earthbound interplanetary shocks (Howard+, 2005)
J/ApJ/710/1111 : Observations of interplanetary shocks (Gopalswamy+, 2010)
J/ApJ/903/125 : MHD simulations cases; Martian bow shock model (Wang+, 2020)
J/A+A/640/A17 : CR Ground Level Enhancements spectra (IGLED) (Usoskin+, 2020)
http://sepem.eu/ : ESA's Solar Energetic Particle Environment Modelling (SEPEM)
application server
http://ipshocks.helsinki.fi/database : Database of interplanetary shocks at
Helsinki university
http://soho.nascom.nasa.gov/data/summary/solarwind/ : the CELIAS/MTOF Proton
Monitor on the SOHO Spacecraft
http://www.ssg.sr.unh.edu/mag/ace/ACElists/obs_list.html : ACE Lists of
Disturbances and Transients
http://lweb.cfa.harvard.edu/shocks/ : CfA Interplanetary Shock Database
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- ID Solar cycle shock number (21-00 to 24-30)
7- 20 A14 --- Time Shock time; YYYY/DOY/hh:mm format
23- 25 A3 --- Inst Spacecraft identifier (1)
27- 68 A42 --- Parent Parent Solar eruption time (2)
70 A1 --- f_Parent Flag on Parent (3)
72- 75 I4 km/s VT [474/2109]? Average transit speed of the shock
to travel from the Sun to 1au
77- 78 I2 deg Theta [17/89]? Angle between upstream B field and
shock normal
80- 81 I2 deg e_Theta [0/39]? Uncertainty in Theta
83- 86 I4 km/s Vsc [278/1106]? Shock speed in spacecraft reference
frame
88- 91 I4 km/s e_Vsc [1/2357]? Uncertainty in Vsc
93 A1 --- f_Vsc Flag on Vsc (3)
95- 97 I3 km/s Vsh [65/577]? Shock speed with respect to upstream
solar wind
99- 102 I4 km/s e_Vsh [3/2358]? Uncertainty in Vsh
104- 107 F4.2 --- rn [1.4/7.9]? Density compression ratio
109- 112 F4.2 --- e_rn [0.01/2.5]? Uncertainty in rn
114- 117 F4.2 --- Mms [0.4/6.2]? Magnetosonic Mach number
119- 122 F4.2 --- e_Mms [0.03/1.3]? Uncertainty in Mms
124- 127 F4.2 --- MA [0.4/9.6]? Alfven Mach number
129- 133 F5.2 --- e_MA [0.1/99]? Uncertainty in MA
135- 138 A4 --- n_MA Flag on MA (4)
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Note (1): The spacecraft identifier as follows:
I = IMP-8,
W = Wind,
A = ACE,
S = SOHO,
SC = time of a geomagnetic storm commencement as a proxy for shock arrival.
Note (2): Initial time of parent solar eruption (i.e., the onset time of
either the X-ray or the Hα flare) temporally associated with
the origin of the SEP event and the IP shock, as documented in
Solar Geophysical Data reports, together with the site of the solar
flare (latitude and longitude in Stonyhurst coordinates, where the
latitude is measured from the solar equator and the longitude from
central meridian with respect to Earth), the Hα classification
of the associated solar flare and its GOES soft X-ray intensity,
and the number of the NOAA Active Region (AR) where the flare
occurred (DSF indicates a disappearing solar filament). When a CME
is also reported in the CDAW LASCO/CME catalog, we add whether the
CME was halo (H) or partial halo (PH) and the estimated plane-of-sky
speed VCME in units of km/s (no narrow CMEs were associated with
the selected events). CME information only available for solar
cycles 23 and 24.
Note (3): Flag as follows:
b = Association based on the study by von Rosenvinge & Reames (1983).
c = Although an intense flare at 137/08:43 N12E57 2B M3.2 AR 11748 and
a fast halo CME 1345 km s$^{-1}$ occurred prior to the shock arrival,
we associate shock and particles with the first solar eruption.
D = We associate shock and particles with the first solar eruption.
a = Theta and shock speed Vsc taken from Terasawa et al. (1995).
Note (4): MX2, MX3 and RH09 indicate the methods described in
Koval & Szabo (2008) and Trotta et al. (2022) that have been used
as alternative to RH08 to compute the shock parameters.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- ID Solar cycle shock number (21-00 to 24-30)
7- 20 A14 --- Time Shock time; YYYY/DOY/hh:mm format
23- 25 A3 --- Inst Spacecraft identifier (1)
27- 34 E8.2 cm-2/s/sr/MeV Ibg1 [-999/1.6]? IMP-8/GME 42.9-51MeV
background intensity (2)
36- 43 E8.2 cm-2/s/sr/MeV Ipk1 [-999/2.9]? IMP-8/GME 42.9-51MeV peak
intensity (2)
45- 52 E8.2 cm-2/s/sr/MeV Ibg2 [-999/0.07]? IMP-8/GME 92.5-107MeV
background intensity (2)
54- 61 E8.2 cm-2/s/sr/MeV Ipk2 [-999/0.2]? IMP-8/GME 92.5-107MeV peak
intensity (2)
63- 70 E8.2 cm-2/s/sr/MeV Ibg3 [-999/18.7] SEPEM 45.7-66.1MeV
background intensity (2)
72- 79 E8.2 cm-2/s/sr/MeV Ipk3 [-999/54.3] SEPEM 45.7-66.1MeV peak
intensity (2)
81- 88 E8.2 cm-2/s/sr/MeV Ibg4 [-999/0.4] SEPEM 95.6-138MeV background
intensity (2)
90- 97 E8.2 cm-2/s/sr/MeV Ipk4 [-999/2.7] SEPEM 95.6-138MeV peak
intensity (2)
99- 100 I02 cm-2/s/sr/MeV Inc1 [00/12]? IMP-8 42.9-51MeV increase (3)
102- 108 A7 --- f_Inc1 Flag on Inc1 (4)
110- 111 I02 --- Inc2 [00/12]? SEPEM 45.7-66.1MeV increase (3)
113 A1 --- f_Inc2 [ de] Flag on Inc2 (5)
121- 129 A9 --- PTime Peak SEPEM 45.7-66.1MeV time; DOY/hh:mm
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Note (1): The spacecraft identifier as follows:
I = IMP-8,
W = Wind,
A = ACE,
S = SOHO,
SC = time of a geomagnetic storm commencement as a proxy for shock arrival.
Note (2): A -999 indicates a data gap.
A -666 in the peak column indicates no significant increase
associated with the shock passage. For those events with peak
intensities of -666 (i.e., class-0 events), the background column
provides the intensity measured at the shock passage.
Note (3): Code as follows:
00 = No increase observed in association with the shock passage.
01 = No increase on almost flat intensity profile.
10 = Clean increase without intervening IP structures.
12 = Increase modulated by prior/intervening IP structures.
Note (4):
d = Interpolated in a data gap.
ERNE-10, ERNE-12 and CPME-10 are alternative classifications of the events
that the lower backgrounds of these instruments allow us to determine,
although they have not been used in this study.
Note (5): Flag as follows:
d = Interpolated in a data gap.
e = Classified as 10 although a slow low-density solar wind structure
preceded the shock.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Jul-2025