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NMDB and space wea he o ecas ing
Pe Yu. Gololobo , Se gey A. S a odub se , Vladisla G. G igo ye , An on S. Z e e
Co espondence
Yu.G. Sha e Ins i u e o Cosmophysical Resea ch and Ae onomy, Sibe ian B anch o he Russian Academy o
Science, Russia,
[email p o ec ed]u
Keywo ds
cosmic ays; neu on moni o ; magne ohyd odynamic wa es; luc ua ions; u bulence spec um
Abs ac
F om he c ea ion o NMDB in 2007 and h ough he g ow h in he numbe o s a ions and he da a accumula ion,
he ShICRA SB RAS g oup con inuously ha e used i s acili ies. Fo he las yea s we ha e c ea ed a me hod
o sho - e m o ecas ing o in ense geomagne ic s o ms wi h an ad ance ime 1-2 days. The p obabili y o
o ecas ing is a ound 80%. We ha e epo ed abou he me hod in he p e ious NMDB: i ual symposium on
cosmic ay s udies wi h neu on de ec o s in 2020. The me hod is based on he global su ey me hod ha was
de eloped in Yaku sk in 1960s and uses he wo ld ne wo k o neu on moni o s as a single mul idi ec ional
de ice. The me hod is in ended o es ima e hou ly dynamics o cosmic ay aniso opy in ee-space. No e
ha only wi h he NMDB c ea ion we managed o implemen i in eal ime mode. Now we s a ed wo k on
c ea ing ano he me hod o space wea he o ecas ing by measu emen s o cosmic ay luc ua ions. Fo his
pu pose, we use 1-min da a o NMDB. In he cu en epo we p esen he i s esul s o ou in es iga ion
on o ecas ing o in ense geomagne ic s o ms wi h Ds < -50 nT. The esul s ob ained indica e he possibili y
o de eloping and implemen ing in eal ime a me hod o p edic ing s ong geophysical mani es a ions o
space wea he on he basis o g ound-based cosmic ay measu emen s.
1. In oduc ion
The sea ch o e ec i e and imely space wea he o ecas ing is one o he mos impo an asks o so-
la - e es ial ela ionships. This is due o he ac ha i s change and subsequen impac on he Ea h
is po en ially nega i e. Fi s o all, his conce ns geomagne ic s o ms, which can lead o a ious kinds
o nega i e e ec s on echnological sys ems as, o example, communica ion dis up ion o powe g id
ailu es. Wi h he de elopmen o mode n elec onic echnology and space explo a ion, he ele ance o
sol ing his issue is as high as e e .
Obse a ions o he s a e o nea -Ea h ou e space a e adi ionally ca ied ou by di ec measu e-
men s o he pa ame e s o he in e plane a y medium wi h a ious de ec o s ins alled on boa d space-
c a . A he same ime, spacec a , as a ule, a e loca ed in ela i e p oximi y o he Ea h and a e able
o p edic wi h g ea accu acy he mani es a ions o changes in space wea he on Ea h o abou 1 hou .
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In his sho ime, i is p ac ically impossible o ake eal p e en i e measu es o any kind. On he o he
hand, his is possible i , o he pu poses o space wea he o ecas ing, g ound-based CR measu emen s
a e used, which, due o hei long mean ee pa hs, ca y in o ma ion abou he p ope ies o he in e pla-
ne a y medium on la ge scales. A simila app oach o space wea he o ecas ing has been de eloped by
many esea che s (as an example, some o hem can be men ioned (Ma omichalaki e al. 2006; Biebe
e al. 2004; Kudela e al. 2000)).
Since he ea ly 2000s we a e wo king on de eloping a space wea he o ecas ing echnique based
on g ound-based measu emen s o cosmic ays (G igo ye e al. 2011; G igo ye e al. 2015). Thus, he
c ea ion o a da abase o neu on moni o s ins alled on he wo ldwide ne wo k o CR s a ions (NMDB)
in 2007, which p o ides eal- ime measu emen da a, allowed us o begin he p ac ical implemen a ion
o he space wea he o ecas ing algo i hm based on he global su ey me hod de eloped in Yaku sk
a he end o he 1960s. In pa icula , some o he esul s o his wo k we e p esen ed a he p e ious
NMDB symposium in 2020 (Gololobo e al. 2020). I was shown ha he spa ial-angula dis ibu ion
o CR expe iences changes ha a e ypical only o pe iods be o e he a i al o geoe ec i e sola wind
dis u bances, which can lead o s ong geomagne ic s o ms wi h Ds < -50 nT. In his case, 1 hou CR
egis a ion da a a e used, and he me hod de eloped by us makes i possible o p edic such s o ms wi h
80% p obabili y.
Ano he app oach o space wea he o ecas ing is o use he eco ding CR in ensi y luc ua ions (G i-
go ye e al. 2008). CR luc ua ions a e unde s ood as non-s a iona y a ia ions wi h pe iods o less han
2-3 hou s (wi h a equency o mo e han 10-4 Hz), which a e obse ed only du ing la ge-scale sola wind
dis u bances. In connec ion wi h his ci cums ance, he p esen wo k is de o ed o he de elopmen o
a me hod o p edic ing space wea he om g ound-based measu emen s o CR in ensi y luc ua ions.
2. CR in ensi y luc ua ions
As es ablished back in he 1970s, CR luc ua ions a ise as a esul o modula ion o high-ene gy CR luxes
(E>1 GeV) by magne ohyd odynamic (MHD) wa es. In his case, he ela ionship be ween he aniso opic
pa o he CR dis ibu ion unc ion and Al én wa es was conside ed by Owens (1974). In his wo k, i
was shown ha he powe spec a o luc ua ions o CRs P
CR
(
ν, μ, V
)
and he in e plane a y magne ic ield
(IMF) ans e se componen s P
B⊥
(
ν
)
a e ela ed by he ela ion:
P
CR
(
ν, μ, V
)
_
j
0
2
= C
(
ν, μ
)
P
B⊥
(
ν
)
_
B
0
2
δ
∥
2  ∼  10
−6
P
B⊥
(
ν
)
_
B
0
2
whe e B
0 is he a e age in ensi y o he IMF, j
0 is he CR lux, V is he CR eloci y in cm·s-1, δ
∥  ∼
U
⁄
c  ∼  10
−3
is he CR lux aniso opy along he magne ic ield, U and c a e he sola wind and ligh eloci ies, C ( ν, μ )
is a pa ame e ha akes in o accoun he nonlinea in e ac ion nea esonan equencies, μ is he pi ch
angle o he pa icle, ν is he equency.
On he o he hand, in he wo k o Be ezhko and S a odub se (Be ezhko & S a odub se 1988) i was
es ablished ha in he p esence o as magne osonic wa es (FMW) in he sola wind, which a e capable
o modula ing he main, iso opic pa o he CR dis ibu ion unc ion, he spec a o CR luc ua ions and
he IMF modulus a e ela ed by he ela ion:
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P
CR
(
ν
)
_
j
0
2
=
[
(
γ + 2
)
C
a
(
C
W
+ Usinφ
)
_________________
3π
√
_
2
k
⊥
ν
]
2
P
B
(
ν
)
_
B
0
2
∼
(
10
−2
÷ 1
)
P
B
(
ν
)
_
B
0
2
whe e he wa e eloci y is C
W  =
√
_
(
C
a
2 + C
S
2
)
, C
a and C
S a e he eloci ies o he Al en and magne osonic
wa es, k
⊥ is he ans e se pa icle di usion coe icien , φ is he angle be ween he sola wind di ec ion
and he IMF o ce lines.
In Be ezhko & S a odub se (1988) i was shown o a numbe o e en s ha i is ela ion (2) ha is
applicable o desc ibe he spec um o CR luc ua ions in he equency ange abo e 10-4 Hz, which is
di ec e idence o he gene a ion o CR luc ua ions p ecisely by FMS wa es. Mo eo e , e idence was
gi en ha his ype o MHD wa es is gene a ed by lows o sup a he mal pa icles, which a e o en
obse ed ahead o he on s o in e plane a y shock wa es. And since hey o en cause s ong geoma-
gne ic s o ms, he e y egis a ion o CR luc ua ions in g ound-based de ec o da a can be an e ec i e
p edic o o hese s o ms
.
3. Me hod
To de e mine CR in ensi y luc ua ions in he ine ial pa o he u bulence spec um, we use 1-minu e
measu emen s. I should be no ed ha he huge a ay o measu emen da a om neu on moni o s wi h
high empo al esolu ion, accumula ed by he wo ld ne wo k o CR s a ions, is p ac ically no used in any
way, excep o he analysis o a e cases o GLE e en s, and lies unclaimed. He e we use ba ome ic-co -
ec ed 1-min da a om he Yaku sk (62.02ºN, 129.72ºE, R
c =1.65 GV) and Tixie Bay (71.60ºN, 128.90ºE,
R
c =0.53 GV) neu on moni o s. These s a ions a e pa o he Russian na ional ne wo k o CR g ound s a-
ions, whose da a a e ansmi ed o he NMDB se e in eal ime. Bo h o hese s a ions a e loca ed ai ly
close o he same me idian, and he asymp o ic angles o a i al o pa icles a hem coincide ai ly well.
Fluc ua ions in CR and he in e plane a y medium we e analyzed using he s anda d Blackman-Tukey
me hod (Blackman & Tukey 1958). In pa icula , o each s a ion we calcula ed au o-spec a o CR powe 
P
xx
(
)
P
xx
(
ν
)
= 2∫ w
(
τ
)
R
xx
(
τ
)
cos
(
2πντ
)
dτ
whe e R xx (τ) is an au oco a iance unc ion, w (τ) is Tukey’s co ela ion window, equal o
w
T
(
τ
)
=
1
_
2
(
1 + cos
πτ
_
m
)
, τ ≤ m
w
T
(
τ
)
= 0,τ > m
Also, c oss powe spec a o CR luc ua ions we e calcula ed o bo h s a ions. I s alues can be w i en as
he sum o he eal and imagina y pa s o he spec um componen s:
P
xy
(
ν
)
=  C
xy
(
ν
)
+ j ⋅ Q
xy
(
ν
)
,
whe e C xy (ν) and Q xy (ν) a e cospec um and quad a u e spec um.
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In his case, along wi h he spec al powe o he signal, he cohe ence coe icien Г
xy was de e mined,
which de e mines he igh ness o he connec ion be ween he luc ua ions o wo quan i ies. The cohe -
ence coe icien is de ined as he posi i e alue o he squa e oo o he cohe ence unc ion:
Γ
xy
(
ν
)
= +
√
_
P
xy
2
_
P
xx P
yy
.
The cohe ence ac o can also be used o de e mine he ype o MHD wa e. Fo example, i is known ha
Al en wa es a e cha ac e ized by high alues o he cohe ence coe icien be ween he s eng h o he
IMF and he sola wind eloci y, FMW — be ween he IMF s eng h and he sola wind densi y, and slow
magne osonic wa es — be ween he sola wind eloci y and densi y.
4. Resul s ob ained
We ha e analyzed mo e han 100 cases o obse a ion in he 23 d and 24 h cycles o sola ac i i y o
s ong geomagne ic s o ms cha ac e ized by Ds <-50 nT. He e, as an example, we will conside only one
e en o a s ong geomagne ic s o m wi h a Ds -index o abou -80 nT ha occu ed on Sep embe 20,
2015. Ou esul s a e shown in Figu e 1. I s analysis shows ha in he ime pe iod 2015 Sep embe 18
(00:01 UT)-19 (00:00UT), a clea inc ease in he cohe ence coe icien Γ
Bn was obse ed in he equency
ange <10-3 Hz o he conside ed spec um, which indica es he p edominan ole o FMS wa es in he
o ma ion o he spec um o IMF luc ua ions.
Fig.1: Powe spec al densi ies PB and PFMS, as well as cohe ence coe icien s be ween ΓBn o di e en ime pe iods.
Cosmic ay s udies wi h neu on de ec o s | Volume 2 (2023) 85
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O e he same ime pe iods, we de e mined he cohe ence coe icien s be ween luc ua ions in he CR
in ensi y eco ded a he Yaku sk and Tixie Bay Γ
NM s a ions. The esul s ob ained a e p esen ed in Figu e
2. I is ob ious ha Γ
NM also shows high alues in he low equency egion. Thus, high alues o he co-
he ence coe icien be ween neu on moni o s a ions can indica e bo h he p esence o FMS wa es in he
sola wind and an impending geomagne ic s o m.
Le us conside he possibili y o using he cohe ence coe icien Γ
NM as a geomagne ic dis u bance p e-
dic o . To do his, we will conside he highes alues o he cohe ence coe icien Γ
NM in he en i e spec-
um ange wi h a s ep o 1 hou o Sep embe 18-20, 2015. The esul s ob ained a e shown in Figu e 3.
As can be seen om Figu e 3 (le panel), 18 hou s be o e he s o m ha began on Sep embe 20, 2015,
high alues o Γ
NM we e obse ed. A he same ime, he esul s o measu emen s o he luxes o supe -
he mal p o ons ca ied ou on he WIND spacec a (Figu e 3, igh panel, h ps://omniweb.gs c.nasa.
Fig. 2: Cohe ence coe icien be ween CR luc ua ions acco ding o measu emen s o neu on moni o s Yaku sk and
Tixie Bay
Γ
NM
.
Fig. 3. Le panel: cohe ence coe icien s
Γ
NM
and Ds -index o Sep embe 18-20, 2020. Righ panel: measu emen da a
o p o on luxes in 9 di e en ial ene gy channels (P1 = 0.130-0.163 MeV, P2 = 0.163-0.233 MeV, P3 = 0.233-0.325 MeV,
P4 = 0.325–0.457 MeV, P5 = 0.457–0.653 MeV, P6 = 0.653–0.884 MeV, P7 = 0.884–1.270 MeV, P8 = 1.270–1.740 MeV, P9 =
1.740–2.510 MeV) by he WIND spacec a o e a pe iod o 18-20 Sep embe 2015.

86 Cosmic ay s udies wi h neu on de ec o s | Volume 2 (2023)
KIEL-UP • DOI: 10.38072/2748-3150/p33
go / o m/sc_me ge_min1.h ml) show ha hei g ow h coincides wi h he obse a ion o high alues o
Γ
NM . Consequen ly, supe he mal p o ons can be a sou ce o FMS wa es.
Thus, aking in o accoun he beha io o 𝚪
NM in o he e en s, i can be assumed ha i is an e ec i e
p edic o o geomagne ic dis u bances o medium- e m space wea he o ecas ing.
5. Conclusions
1. I is once again con i med ha be o e he a i al o in e plane a y shocks a he Ea h’s o bi , in he
ine ial pa o he sola wind u bulence spec a in he equency ange ~10
-4
÷ 10
-2
Hz, FMS wa es o
signi ican ampli ude a e o en obse ed.
2. FMS wa es a e gene a ed by luxes o supe - he mal pa icles wi h ene gy Ep~1 MeV in he icini y o
he shock on .
3. The lux o galac ic CRs has been subjec o modula ion by FMS wa es, which mani es s i sel in cohe -
ence as he appea ance o signi ican CR luc ua ions a equencies ~10
-4
÷ 10
-2
Hz.
4. The esul s ob ained indica e he possibili y o de eloping and implemen ing in eal ime a me hod o
p edic ing s ong geophysical mani es a ions o space wea he based on g ound-based measu emen s
o CR in ensi y.
Acknowledgemen s
The wo k was ca ied ou wi hin he amewo k o he Russian Science Founda ion p ojec No. 22-22-
20045. The Yaku sk CR s a ions and Tixie Bay a e pa o he unique scien i ic acili y o he Russian
Fede a ion ‘Russian Ne wo k o Cosmic Ray G ound S a ions’ and NMDB.
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