E-layer ionization and solar X-ray emission in 44-60 angstrom ban

Letfus, V.

Serafimov, K.

English

NASA Technical Reports Server

. I 
National Aeronautics and Space Administration 
Goddard Space Fl ight  Center  
Contract  No. NAS-5-9299 
S T  - AI - SP - 10500 
IONIZATION OF THE E-LAYER AND X-RAY EMISSION OF 
THE SUN IN THE 44 - 60 BAND 
V. Letfus 
K. Serafimov 
I (USSR) 
N 0 
a I (ACCESSION NUWDER) ITHRUI 
IL 
-., -- - -  
GPO PRICE $ 
CFSTI PRICE(S) $ 
I 
Microfiche (M F) d7a 
ff 653 July 66 
. 
8 J U N E  1966 
https://ntrs.nasa.gov/search.jsp?R=19670004245 2020-03-16T17:12:39+00:00Z
ST - A I  - SP - 10 500 
I O N I Z A T I O N  O F  THE E-LAYER AND X-RAY EMISSION OF 
THE SUN I N  THE 44-60 i BAND* 
Geomagnetizrn i Aeronomiya 
Tom 6,  No.2,352-356, 
I z d a t e l l s t v o  "NAURA" , 1966 
by V. L e t f u s  
K. Serafimov 
S U M M A R Y  
When computing t h e  c h a r a c t e r i s t i c  number of the  E- layer ,  i t  is 
necessary  t o  s e t  a s i d e  t h e  seasonal  course  i n  t h e  aeronomic parameters  
and t ake  i n t o  account t h e  temperature  v a r i a t i o n s  with he igh t  and t i m e .  
annual dependence of t h e  va lues  of  t h e  c h a r a c t e r i s t i c  number on the zeni-  
t h a l  angle  of  t he  Sun. 
The c h a r a c t e r i s t i c  numbers, ob ta ined  i n  this fash ion  i n  t h e  y e a r  
(1964) of t h e  q u i e t  Sun at one s t a t i o n ,  correspond we l l  t o  t h e  i n t e n s i t y  
of s o l a r  X-ray emission i n  t h e  44- 60 1 band. 
T o  t h a t  e f f e c t  i t  is appropr i a t e  t o  c o n s t r u c t  a graph of  t h e  
The i n v e s t i g a t i o n  of the  sou rce  of i o n i z a t i o n  and of t he  charac- 
t e r i s t i c  number o f t h e E - l a y e r  has a s i g n i f i c a n t  va lue  for h e l i o p h y s i c s ,  
the a s o e r t a i n i n g  of  t h e  i o n i z a t i o n - n e u t r a l i z a t i o n  processes  i n  t h e  iono- 
s p h e r e ,  f o r  c e r t a i n  problems of aeronomy and a lso  for rad ioprognos is .  
The s u f f i c i e n t l y  we l l  known v a r i a t i o n  of e l e c t r o n  concen t r a t ion  
m a x i m u m  o f  t h e  E-layer (NmE) provide t h e  p o s s i b i l i t y  of improving t h e  
i n v e s t i g a t i o n  of t h i s  ques t ion ,  which h a s  been t h e  o b j e c t  of  numerous 
works C 1  - 6 3 ,  
f o r  t h e  c h a r a c t e r i s t i c  number, assumed t o  be p r o p o r t i o n a l  t o  the  i n t e n s i t y  
of the  i o n i z a t i o n  source .  Th i s  s c a t t e r i n g  i c ;  i n  c o n t r a d i c t i o n  w i t h  t h e  
r e g u l a r  N,$ v a r i a t i o n s  and t h i s  i E i  why i t  i s  obviously necessary  t o  
However, t h e  r e s u l t s  obtained show a s i g n i f i c a n t  data s c a t t e r i n g  
* 1ONIZAT.SIYA SLOYA E I RENTGENOVOYE IZLUCHENIYE SOLbTTSA V DIAPAZONE 
44- 60 A. 
2. 
c o r r e c t  t he  method of computation of  the  c h a r a c t e r i s t i c  number. Such cor- 
r e c t i o n s  may be made by u t i l i z i n g  the  new aerodynamic data and t h e  cor res -  
ponding express ions  of  t h e  l i n k  with t h e  c h a r a c t e r i s t i c  number. 
For a p r e c i s e  determinat ion of t h e  c h a r a c t e r i s t i c  number i t  is 
necessary ,  f i r s t  of a l l ,  t o  start from t h e  c o r r e c t  form of t h e  ion iza t ion -  
n e u t r a l i z a t i o n  balance equat ion.  
t h i s  equat ion has  t h e  form c71 
We may estimate t h a t  f o r  t he  E-layer  
dN,,,iY 
-- - qo,,, C O P ~  - aNn,E2, 
dl 
n = 1 + y - V .  
Here qom i s  the  maximum e l e c t r o n  product ion,  r e f e r r e d  t o  t h e  maximum 
value  of t he  s c a l e  he igh t  Ho ( the value q&, is QO,,, == of,/ Ifocsp 1, where 6 is 
t h e  i o n i z a t i o n  c r o s s  s e c t i o n ,  I, is  t h e  i n t e n s i t y  of t h e  i o n i z i n g  agent  
beyond the  absorbing medium); )L is the  z e n i t h a l  angle of the  Sun; Qc is t h e  
equ iva len t  recombination c o e f f i c i e n t ;  Y is t h e  Bcale he igh t  g r a d i e n t ;  0 is  
t h e  exponent of t h e  e f f e c t i v e  cosine l a w  r e l a t i v e  t o  d i u r n a l  s c a e  he igh t  
v a r i a t i o n s  c7, 81. The presence of a s i g n i f i c a n t  temperature g rad ien t  i n  
t h e  E-layer  c91 and t h e  s u b s t a n t i a l  v a r i a t i o n s  of t h e  a l t i t u d e  d i s t r i b u -  
t i o n  of t he  mean ma66 of the  i o n i z i n g  components o f  t h i s  l a y e r  [lo] 
show t h a t  the  s c a l e  he igh t  has a g r a d i e n t  y 
(]io = / c y /  Isig), which cannot be neglec ted .  
t h e  q u a s i s t a t i o n a r y  approximation ((LA’/ dt 4 (loni cos” x M d W )  [ 1-61, which is 
v a l i d  f o r  t h e  E-layer i n  t h e  course of t he  whole day, exclauin:; s u n r i s e  
and sunset, when the  Chapman func t ion  has  t o  be u t i l i z e d  c2, 3,  111. 
v a l i d i t y  of t he  q u a s i s t a t i o n a r y  approximation al lows t o  m a k e  use  of t h e  
d i u r n a l  course of c r i t i c a l  f requencies  foE f o r  t he  de te rmina t ion  of t he  
c h a r a c t e r i s t i c  number c2, 31. However, i t  should be noted t h a t  t h e  forms 
o f  t h e  foE (t ) - c h a r a c t e r i s t i c s  have s u b s t a n t i a l  anomalies,  t h a t  induce 
doubt in t he  p o s s i b i l i t y  of app l i ca t ion  of a s i g n i f i c a n t  p a r t  o f  t h i s  
number’s d i u r n a l  values .  Most e s s e n t i a l  i n  t hese  anomalies i s  the  pre-noon 
l a g  i n  t h e  r i s e  of  foE c 3 , 1 2 1 .  
s i n g l e  e f f e c t i v e  value frE is u t i l i z e d  in c23, which i s  obtained by way 
of  c u r v i l i n e a r  or r e c t i l i n e a r  extension of t he  d i u r n a l  dependence 
lgjol:’(lgcos~),  and not t h e  measured values at l o c a l  noontime. 
i n  i ts  a l t i t u d e  d i s t r i b u t i o n  
One usua l ly  determines and u t i l i z e s  t h e  c h a r a c t e r i s t i c  number i n  
The 
I n  o rde r  t o  e l imina te  t h i s  anomaly, a 
3 .  
It seems t h a t  such a method c o n t r i b u t e s  t o  e l i m i n a t i o n  of  random 
v a r i a t i o n s  i n  t h e  m a x i m u m  va lue  of f o E ,  without d i s r u p t i n g  t h e  d i r e c t  
r e l a t i o n s h i p  between the  c h a r a c t e r i s t i c  number and t h e  measured d a t a .  
Besides,  t he  seasona l  v a r i a t i o n s  o f  t h e  aeronomic parameters ,  o f  t h e  fac- 
t o r  and also t h e  influence of a l t i t u d e  v a r i a t i o n  o f  e l e c t r o n  concentra- 
t i o n  m a x i m u m  , are no t  t aken  i n t o  account i n  all works. T h i s  is why t h e  
ob ta ined  results f o r  the  c h a r a c t e r i s t i c  number JE a r e  no t  independent 
from s e a s o n a l  v a r i a t i o n s ,  which i n c r e a s e  the  d i s p e r s i o n  du r ing  t h e  a t t empt s  
t o  f i n d  the  l i n e a r  connect ion between JE, t h e  r e l a t i v e  number R of sun- 
s p o t s  and t h e  Sun’s radioemission C61. 
Our problem c o n s i s t s  i n  c o r r e c t i n g  t h e  computation methods of  t h e  
c h a r a c t e r i s t i c  number, t a k i n g  i n t o  account the  p o s s i b l e  s e a s o n a l  v a r i a t i o n s ,  
and t o  f i n d ,  by t h e  same token,  the  b e s t  c o r r e l a t i o n  between J and the  
va r ious  p o s s i b l e  i o n i z i n g  agen t s ,  
E 
. M E T  H 0 D . - The  va lues  o f  f, E 
The case6 wi th  a sharply-expressed midday decrease o r  l a g  i n  f o E  r e l a t i v e  
t o  COB % m a x i m u m  are  r e j e c t e d .  
of t he  r e s u l t s ,  t h e  use o f  value6 of f o E  
graph is no t  r equ i r ed ,  for t h e  measured va lues  con ta in  t h e  d i r e c t  phys i ca l  
i n fo rma t ion ,  though they  do have more random f l u c t u a t i o n s .  
du r ing  l o c a l  noontime are u t i l i z e d .  
T h i s  is  why,for the  sake  o f  improvement 
i n t e r p o l a t e d  by t h e  l o g a r i t h m i c  
The midday va lues  o f  foE, comparable i n  t h e i r  phys i ca l  c o n d i t i o n s ,  
a r e  obta ined  at a be t t e r  q u a s i s t a t i o n a r y  approximation and undergo a r e l a t i -  
v e l y  f e e b l e r  i n f luence  of the  E,-layer (which, as an average,  h a s  a pre- 
midday m a x i m u m  C l J ] ) ,  o f  t h e  E2 - l a y e r  ( t h e  maximum of cmes of appearance 
a l s o  occurs  at pre-midday time C143) and of  q u a s i p e r i o d i c a l  f l u c t u a t i o n s  
i n  t h e  ionosphere 
b i f u r c a t i o n  c153. For t h e s e  midday v a l u e s  we have 
(wh ich  i n t e r f e l o a t  t h e  beginning and end of F - reg ion  
The c a l c u l a t i o n s  may be performed by u t i l i z i n g  ( 2 )  and some of t h e  
e x i s t i n g  t h e o r e t i c a l  or experimental  models of  T (z), no2 ( a ) , n O  ( a )  and 
(e )  d i s t r i b u t i o n .  However, we do n o t  s u b j e c t  our i n v e s t i g a t i o n  t o  
%2 
dependence on t h e s e  models, though we t end  t o  e l imina te  t h e  seasona l  course .  
T h i s  is why we u t i l i z e  o n l y  ionospher ic  data, As is we l l  known, t h e  h e i g h t  
of e l e c t r o n  concen t r a t ion  maximum i n  t h e  E-layer (z E )  shows s u b s t a n t i a l  
s e a s o n a l  v a r i a t i o n s  c121 
Ho, 6, 6 can be expected. A t  t h e  same time, s easona l  v a r i a t i o n s  of  Ho and 
may be obtained independent ly  from t h e  v a r i a t i o n s  of e E, f o r  t h e r e  may 
take p lace  v a r i a t i o n s  i n  t h e  s ta te  of 02 d i s s o c i a t i o n ,  o f  temperature  and 
o t h e r  causes  , Thus, i n  the  most general  form we assume a = aocos j)lx, f Z o  = Horn cos7’; x ,  
a = aocosP3x, where pl, p2 and p3 may have va lues  g r e a t e r  and s m a l l e r  t han  
ze ro ,  b u t  if anyone of t he  considered parametelsshould no t  be dependent on i”, 
t h e  exponent,  corresponding t o  i t ,  might be zero.  We exclude from t h e  most 
g e n e r a l  case only t h e  i n e r t i a l  seasonal  v a r i a t i o n s  and t h e  dynamic a s y m e t r i c  
i n f l u e n c e s  on account of r e l a t i v e l y  symmetrical  c h a r a c t e r  of  t he  dependence 
f o E  ( t ) .  
m a x  
and that  is why s i g n i f i c a n t  s easona l  v a r i a t i o n s  of 
m a x  
Thus,  f o r  JE we o b t a i n  
no l o n g e r  depends on seasona l  v a r i a -  
E , O  
The c h a r a c t e r i s t i c  number J 
t i o n s  and i t  r e f l e c t e s  d i r e c t l y  the i n t e n s i t y  Var i a t ions  of  t he  i o n i z i n g  
source .  From (2) and ( 3 )  w e  ob ta in  
]E, 0 = I</(? S(’”’’ x. p = 12 + p‘ = 1 + y + p i  - (’ + p:! + p 3 )  ’ (’) 
The exponent p may be found by p l o t t i n g  t h e  annual course of t h e  
dependence 
Ig life' = 12 I E ,  0 - p lg sec x .  ( 5 )  
A t  p = c o n s t  and at i n v a r i a b l e  i o n i z i n g  r a d i a t i o n ,  t h e  dependence ( 5 )  
w i l l  be r e c t i l i n e a r .  Because of t h e  d a i l y  v a r i a t i o n s  of  i o n i z i n g  r a d i a t i o n  
t h e r e  appear  r egu la t ed  d e f l e c t i o n s  from t h i s  s t r a i g h t  l i n e ,  t h a t  superimpose 
themselves on t h e  random s c a t t e r i n g s  and d e v i a t i o n s  induced by measurement 
and e s t ima te  inaccurac i e s .  T h i s  is why i t  is p r a c t i c a l  t o  e f f e c t  such an 
a n a l y s i s  at low solar a c t i v i t y ,  when t h e  v a r i a t i o n s  of  J a r e  minimal E. 0 
and t h e  d i r e c t  e f f e c t  o f  s o l a r  chromospheric f la res  c o n t r i b u t e s  i n s i g n i f i c a n t -  
l y .  From the  s t r a i g h t  l i n e ,  obtained at t h e s e  cond i t ions  i n  loga r i thmic  s c a l e  
of (51, we m a y  f i n d  the  exponent p. U t i l i z i n g  ( 5 )  f o r  a known p,  we s h a l l  
. 
determine t h e  annual v a r i a t i o n s  of J With t h e  a i d  of t h e  l a t t e r  we 
may t h e n  sea rch  f o r  a c o r r e l a t i o n  with the  v a r i a t i o n s  of  d i f f e r e n t  p o r t i o n s  
of  t he  s o l a r  spectrum. 
E, 0 
EXAMPLE OF APPLICATION OF THE METIIOD. - For the  demonstrat ion of  
t h e  p o s s i b i l i t i e s  of t h i s  method we u t i l i z e d  t h e  data of  t he  ionosphe r i c  
s t a t i o n  Monte Cape l l in0  (cp = 44'33'05" N, A = 8'57'29" E). Processed were t h e  
data f o r  12 00 hours  VT o r  approximately 1 2  h. 30 m LT i n  the pe r iod  of 
solar a c t i v i t y  minimum (19641.. The annual d a t a  f i t  s u f f i c i e n t l y  we l l  t he  
l i n e  wi th  p ~ ~ 0 . 7 2 .  Hence t h e  exponent i n  an equ iva len t  cosine l a w  f o r  
t h e  e l e c t r o n  d e n s i t y  of t h e  E-layer is approx ia t e ly  equal  t o  0.32, which 
corresponds t o  the  cosine law f o r  c r i t i c a l  f requencies  with exponent 0.18. 
These r e s u l t s  agree  wel l  with t h e  r e s u l t s  f o r  t he  d a i l y  course obta ined  i n  
c123, and p o i n t  t o  a value of  p d i f f e r i n g  s u b e t a n t i a l l y  from the  u n i t y .  
The requirement o f  t a k i n g  i n t o  account t h i s  s easona l  va lue  of p w i l l  become 
c l e a r e r  i f  the  i n v e s t i g a t i o n  is conducted w i t h  t he  h e l p  of  a wel l  known 
method [I - 51 
t i t y  KfoE 6ec $ 
f o r  the  
cons idered  data is n e a r e r  t h e  r e c t i l i n e a r  w i t h  angular  c o e f f i c i e n t  0.28. 
T h i s  va lue  is e x a c t l y  equal  t o  1 - p, t h a t  is ,  i t  c o n s t i t u t e s  t h e  va lue  o f  
p* + )' - U', co inc id ing  with t h e  r e s u l t s  of  c a l c u l a t i o n s  by t h e  formula 
To t h a t  e f f e c t  we i n v e s t i g a t e d  t h e  dependence of  t h e  quan- 
on % ( t h a t  is,  the dependence on s e a s o n a l  v a r i a t i o n s ) .  4 
It w a s  obtained that the dependence of  l og  K f o E  4 s e c  9 on l o g  
From a n a l y s i s  i t  fo l lows ,  t h a t  i f  t h e  c h a r a c t e r i s t i c  number is com- 
puted with the  a i d  of  the  method apFlied to-da te  E2 - 61, a s i g n i f i c a n t  . 
s e a s o n a l  course would be p r e s e n t  i n  the v a r i a t i o n s  of  J E , O '  
The annual course of' the  value of  J E , O *  computed by formula (5) 
were averaged by w i t h  p % 0.72 is shown i n  Fig.  1. The va lues  of JE, 0 
f ive-day groups. For comparison, the  v a r i a t i o n s  of the r e l a t i v e  number of  
s u n s p o t s  a r e  shown t h e r e  too  (Zi i r ich) .  
expressed  r e l a t i o n s h i p  e x i s t s  between the  c h a r a c t e r i s  t i c s  and the  r e l a t i v e  
number of sunspots .  T h u s ,  no correspondence of  any k i n d  e x i s t s  between t h e  
minima of JE, 0 
It may be s e e n  t h a t  no s h a r p l y  
at t h e  end of January,  May and November and the  maximum 
. 
6. 
I 
7. 
of  J at mid-April and the  corresponding va lues  of  R. Since  t h e  s o l a r  
X - r a y  r a d i a t i o n  is t h e  probable source  of i o n i z a t i o n  of t h e  E-layer,  we 
have shown i n  F ig .  1, f o r  the  sake  of comparison, the  v a r i a t i o n s  of  t h e  s o f t  
component of t h a t  r a d i a t i o n  (44-60 A).  The d a t a  on X-rays were borrowed 
from measurements on the  AES Ariel-1 f o r  t he  pe r iod  from January t o  August 
1964 Ci61. 
E, 0 
0 
E, 0 corres- 
It may be s e e n  from the  graph t h a t  t he  v a r i a t i o n s  of  J 
pond w e l l  t h e  v a r i a t i o n s  of i n t e n s i t y  Fb4 - 
well explain t he  minima at the  end of  January and May, and also t h a t  of nid- 
Apr i l .  The at tempt  t o  f i n d  a r e l a t i o n s h i p  between J 
band6 of  t h e  shortwave po r t ion  of t h e  e o l a r  spectrum f a i l e d  t o  provide good 
r e s u l t s .  The same r e f e r s  t o  s o l a r  r a d i o  emission,  f o r  i t  should  be borne 
i n  mind t h a t  t he  extreme6 i n  F44 - 60ft  
not  c o r r e l a t e  with s o l a r  r a d i o  emission extremes i n  the  frequency of  2800 Mc 
h61.  
t h e  most probable i o n i z i n g  agent  i n  t h e  near-maximum region  of the  E-layer.  
This  correspondence may 
and t h e  o t h e r  E, 0 
dur ing  the  per iod  cons idered ,  do 
Hence i t  fol lows t h a t  the X-rEy r a d i a t i o n  i n  the 44- 60 i band is 
The r e s u l t s  of i n v e s t i g a t i o n s  of  ionosphere e f f e c t s  of t he  s o l a r  
e c l i p s e  of  1961 [17,181 agree wel l  w i th  t h i s  a s s e r t i o n ,  j u s t  as do t h e  
observed v a r i a t i o n s  i n  the  E-layer a t  time of  chromospheric f l a r e s ,  when 
mostly t h e  X-ray emission of  t h e  Sun is enhanced C191, 
The l i m i t e d  p r e c i s i o n  of  t h e  u t i l i z e d  ionospher ic  data (publ i shed  
w i t h  a p r e c i s i o n  t o  0.1Mc) h inders  t h e  more accu ra t e  de te rmina t ion  of t he  
c o r r e l a t i o n a l  l i n k  between JE, 
t h e  q u a l i t a t i v e  p i c t u r e  obta ined  here  i n  regard t o  t h i s  l i n k  r e f u t e s  t h e  
a s s e r t i o n s  of  k 1  
p o s s i b i l i t y  of making conclusions r e l a t i v e  t o  It is however necessary  
t o  average these  data over  s h o r t  pe r iods  of  t i m e .  The ionosphe r i c  measure- 
ments a l low t o  i n c r e a s e  the  p r e c i s i o n  t o  0.02Mc, and, by t h e  same token,  
t o  r e f i n e  t h e  dependence obtained here .  
2nd the  i n t e n s i t y  of X- r a d i a t i o n .  However, 
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D I S T R I B U T I O N  
same 86 for 10499; add 3 papers t o  GSFC 614 


Ionization of the E-layer and X-ray Emission of the Sun in the 44-60 Angstrom Band

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