Relation between theoretical and observational models of atmospheric properties and changes during decreasing solar activit

Harris, I.

Priester, W.

English

NASA Technical Reports Server

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RELATION 6ETWEEN 
~ THEORETICAL AND 
OBSERVATIONAL MODELS 
OF 
THE UPPER ATMOSPHERE 
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JULY 1963 
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GODDARD SPACE FLIGHT CENTER 
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https://ntrs.nasa.gov/search.jsp?R=19650020079 2020-03-24T04:51:58+00:00Z
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Relation between Theoretical and 
Observational Models of the Upper 
Atmosphere 
by 
I. H a r r i s  
Goddazd Space Fl ight  Center, Greenbelt, Md . 
and 
W .  Pr ies ter  
Bonn University Observatory 
July 5 ,  1963 
. In  a previous paper [Harris and Priester (1962)] we published theore- 
t ical  working models for the solar-cycle variation of' thz upper atmosphere 
based upon a working hypothesis concerning thz dependence of the heat sources 
on the solar  ac t iv i ty .  Therein it was assumed - faute de mieux - t ha t  the 
fluxes of both heat sources (extreme u l t rav io le t  f lux and "corpuscular" heat 
f lux) vary i n  proportion t o  the monthly averages of the solar 10.7 cm flux, 
which is  generally used as an indicator of solar ac t iv i ty .  Consequently 
the model parameters S of the theoretical  models were taken equal t o  the 
monthly averages of the 10.7 cm flux. 
I n  addition t o  the comparison made previously with data  fo r  high 
solar  ac t iv i ty  it is  now possible t o  compare these models a l so  w i t h  obser- 
vational data  obtained during times of medium and low solar  ac t iv i ty .  T h i s  
leads t o  an improvement of the working hypothesis. 
used are the models by D.G.  King-Hele (1963) for the years 1958/59, 1360, 
1961 and 1962. 
The observational r e su l t s  
An appreciably good agreement i s  found fo r  a l l  l eve l s  of 
solar a c t i v i t y  i n  the comparison wi th  the theoret ical  models i f  one regards 
how la rge  the density changes are during the solar cycle. Towards the low- 
e s t  l e v e l  of solar  ac t iv i ty ,  however, a systematic deviation appears. This 
y ie lds  an empirical re la t ion  between the monthly averages of the solar 
10.7 cm flux and the model parameters S which i s  shom i n  Fig. 1. This 
r e l a t ion  now replaces the working hypothesis used previously, and any user 
of our theoret ical  models should take the appropriate model according to 
t h i s  r e l a t ion .  The data  given by D.G.  King-Hele (1963) a re  yearly averages, 
- 2 -  
which a re  not corrected for  the semiannual and annual var ia t ion [H.K.Paetzold 
(1.363)]. Our theoret ical  models on the other hand are  generally applicable 
t o  average values f o r  the months September through December. This i s  duz t o  
the f a c t  t h a t  the observational model by H.A.Martin e t  a1.(1961), on which 
the theoret ical  models are  based, apply t o  the average dens i t ies  of the months 
given above. Therefore one may consider the curve i n  Fig. 1 as a lower l i m i t .  
I n  par t icular  the open c i r c l e s  fo r  = 150 and 100 might be placed s l igh t ly  
too low. 
M .Roemer (1963) . 
A more refined analysis is presently being carr ied out by 
In  Fig. 2 t o  5 the comparison i s  shown between the observational and 
theoret ical  models u t i l i z ing  the new relationship.  The observational day 
time maximum curve i n  Fig. 2 belongs t o  the year 1958 where the average oL7 
the solar  10.7 c m  f lux w a s  230. This accounts fo r  the deviation from the 
theoret ical  model for  an average flux of 200. 
In  Fig. 3 the merging of the observational curves f o r  day time and 
night time a t  300 km i s  believed t o  be influenced by the method of extra- 
polation t o  lower a l t i tudes .  
(1962)] make 2 cross over between day and night curve very unlikely a t  a n  
Theoretical considerations [ H a r r i s  and Priestci- 
a l t i t ude  as high a s  300 km. Furthermore, L.G.Jacchia and J.Slowely (1962) 
found an appreci&ly larger  diurnal amplitude a t  350 km from Explorer I for 
the yezr 1960. 
In  Fig.  k i t  i s  seen tha t  towards low solar a c t i v i t y  the diurnal ampli- 
The theory shows tha t  t h i s  phenox- tude increases zt low a l t i t udes  (300 km). 
enon follows fron ';he lowering of the atomic oxygen layer  during the decreasii2z 
phase of solar ac t iv i ty .  
- 3 -  
The pronounced increase of thz sca le  height a t  higher a l t i tudes  (zbo?rc 
6 0 ~  km) (as seen i n  Fig 4) can be explained by the lowering of the helium 
layer. The smaller diurnal mplitud.: i n  the observational curves above 
600 km indicates that a greater  amount of helium must be present than assuned 
i n  the theoret ical  models. M.Roemer (1963) finds a be t t e r  agreement w i t h  
data  obtained from Echo I when using a theoret ical  model which has a 2.5 
times greater amount of helium [I.Harris.(lg63)] than i n  the theoret ical  
I 
models mentioned above. 
are compmed with the appropriate data by K i n g - H e l e .  
I n  Fig. 5 densi t ies  of this new model for S = 100 
The agreement between 
theory and observations is obviously even better as i n  Fig. 4. In  the models 
f o r  higher l eve l s  of solar a c t i v i t i e s  (S = 150) no noticeable increase of 
dens i t i e s  f o r  h Lghts up t o  70s km occurs due t o  the increase of the auc3cr 
density N of helium by a factor of 2.5 a t  the boundary [N(He)=6.25*10 7 cr.1 - -  ' 
a t  an a l t i t ude  of 120 ka]. 
cable f o r  the new models. 
For this reason Fig. 2 and 3 are a l s o  appli-  
Also shown i n  Fig. 4 and 5 i s  a result obtained by Explorer XVII 
[R.Horawitze e t  al. (l963)] which f i l l s  a gap i n  our knowledge at  low 
a l t i t u d e s  (below 300 km) for times of low solar ac t iv i ty .  
l o c a l  time, on A p r i l  3, 1963 at 260 kn a l t i t ude  and temperate l a t i t udes  
the measured deusity w a s  2.7 *d4 g ~ m ' ~ .  The average solar 10.7 cm I'lux 
w a s  about 75 i n  the usual un i t s .  Thus, using the r e l a t ion  shown i n  Fig. I 
a theore t ica l  mode7 .%;ith parameter S = 100 is applicable. 
A t  2l:OO hours 
If one p lo t s  the nighttime- and daytime- temperatures of the theoreti-  
c a l  models using the new empirical re la t ion  (Fig. 1) one obtains an excellent 
- 4 -  
agreement with the nighttime-temperatures derived by L .G. Jacchia (1963) 
who used M.Nicholet's (1961) models fo r  the conva-sion of observed dens i t ies  
i n to  temperatures (Fig. 6 ) .  The daytime temperatures shcw a systematic d i f -  
ference of about 100 t o  150 OK. 
1) For a given density a t  any height Nicholet 's models furnish one value 
fo r  the temperature independent of local  time contrary t o  the Harris-Priester 
models, where the r e l a t ion  between density and temperature a t  a given height 
depends on loca l  time (Fig. 7 ) .  
models are  solutions of the time-dependent heat conductian equation. 
fore the use of Nicolet 's  models for  conversion of density in to  temperature 
would lead t o  a diurnal temperature amplitude which is  too small. The d i f -  
ference depends on the a l t i t ude  and the leve l  of solar  ac t iv i ty .  
data  used by L.G.Jacchia the difference may be estimated t o  be about 50 t o  
100 OK. 
observational model of Bonn Observatory 1961 [H.A.Martin e t  al. (1961)l. 
There a re  indications tha t  the diurnal amplitude i n  t h i s  model i s  s l igh t ly  
This could be explained by two reasons: 
This i s  due t o  the f a c t  that the l a t t e r  
There- 
For the 
2) The theoret ical  models of H a r r i s  and Pr ies te r  a r e  based on the 
too large,  which again can account for  a difference of 50 t o  100 OK. 
Conclusions: 
from 1958 t o  1963 has shown that the theoret ical  models give agoodrepresen- 
t a t i o n  of the atmospheric properties and the i r  changes during the decreasing 
phase of solar  ac t iv i ty  i f  the re la t ion  given i n  Fig. 1 is used. 
b e t t e r  agreement is  obtained i f  i n  the theoret ical  models the amount of 
helium is  increased by a factor  of 2.5 a t  the boundary of 120 km. 
howver, is  important fo r  periods of very low solar  a c t i v i t y  only. 
The comparison with a i r  densi t ies  observed within the period 
A s t i l l  
This, . 
- 5 -  
Further comparisons with forthcoming data for  the years 1965 through 1968 
will.reveal whether the same empirical re la t ion  holds also for  the imreas ing  
phase of the 11-year cycle. 
- 6 -  
Rerererlces : 
H a r r i s ,  I. and W. Priester :  
‘ J.Geophys.Res. 6 7  4585 - 4591 (1962) 
Theoretical Models f o r  the Sol=-Cycle Variation of the Upper Atmosphere. 
and NASA Techniz; Note D-1444 (1362) 261 pp. 
H a r r i s ,  I.: unpublished calculations. 
Horowitz, R .  : Report a t  the AGU meeting, Washington, D.C., April 1963. 
Jacchia, L.G.: 
Atmospheric Structure and i t s  Variations a t  Heights above 200 km. 
Report t o  COSPAR Working Group IV, presented a t  the Fourth Inter-  
national Space Science Symposium, Warsaw, June 1963. 
Jacchia, L.G. and J. Slowey: 
Accurate Drag Determinations f o r  Eight Ar t i f i c i a l  Sa t e l l i t e s ;  
Atmospheric Densities and Temperatures. 
Smithsonian Astrophys . Obs . Spec .Rep. No. 100 (1962) 117 pp. 
King-Hele, D .G. : 
Decrease i n  Upper-Atmosphere Density since the Sunspot Maximum of 
1957-58 _ _ .  - 
Nature e, 832-834 (1963). 
King-Hele, D . G .  and J.M.Rees: J.Abos.Phys. ( i n  the press).  
Martin, H.A., W .Neveling,W .Priester and M.Roerner : 
Model of the Upper Atmosphere from 130 through 1600 km, Derived from 
S a t e l l i t e  Orbits. 
Space Research 11 (ed.H.C.van de H u l s t ,  C.de Jager and A.F.Moore) 
p . 902-917, North-Holland Pub1 . Comp . , Amsterdam 1961. 
Nicolet,M. : 
Density of the Heterosphere Related t o  Temperature. 
Smithsonian Astrophys .Obs . Spec .Rep. No. 75 (1961) 30 pp. 
Paetzold,H.K. : 
Solar Activity Effects  i n  the Upper Atmosphere. 
Space Research 111 (ed.by W.Priester) Amsterdam 1963 p. 28 - 52.  
Roemer,M. : 
Exospheric Densities Deduced from S a t e l l i t e  Drag Data. 
Paper presented a t  the Fourth International Space Symposim 
Warsaw, June 1963 
Roemer,M. : 
Theses Bonn University 1963 ( t o  be published i n  Verijff. der Univ.- 
Sternwarte Bonn). 
Captions of Figures 
Rmnpirical. re la t ion  bc.Lwc~;i H .  -P. model number S and the monthly 
averages or  the so3ar 1.0.7 crfl-flux f;; as obtained from comparisor. 
Fig. 1: 
with obser*vai;ional daia: o cn c i rc lcs :  models by D.G.King-Hele 
f o r  1958/53, 1960, 1961, l h e ?  F i r s t  data by Explorer - 
XVII, launched April 2, 13bj; f i l l e d  c i rc le :  Bonn modcl for  F=200. 
The dotted s t ra ight  l i ne  represents tiic ii??l iifii il:.ry vorli in~);  h y ~ ~ o  
thes i s  used i n  the paper by Harris arid Priesicr (1.562). 
Fig. 2 - 4: Maximum daytime and minimum nighttiix: densities obtained by 
D . G .  King-Hele from a large numbcr 01 S a t e l l i t e s  a re  compared 
with the corresponding theoretical  models by Harris and Pr ies te r .  
In  Fig. 4 the density measured on April 3, 1963, 21:OO hours 
loca l  time by Explorer XVII i s  a l so  given. 
Fig. 5: Comparison between King-Hele ' s observed dens i t ies  f o r  1962 with 
a new theoret ical  model containing an amount of helium increased 
by a fac tor  2.5 w i t h  regard t o  the previous models. 
the density obtained by Explorer XVII is  a l so  given. 
A s  i n  Fig. 4 
Fig. 6: Relation between exospheric temperature and the monthly averages 
of the solar 10.7 cm-flux F. 
sent s a t e l l i t e  drag data by L.G.Jacchia (1963) f o r  night- and 
day-time respectively.  
Nicholet 's model. The large c i r c l e s  give the temperatures of 
H.-P. models fo r  4 and 1 4  hours loca l  time based on the empiri- 
ca l  re la t ion  (Fig. 1). 
The dots and small c i r c l e s  repre- 
The temperatures are derived using 
Fig. 7: Relation between density and temperature for  e ight  d i f fe ren t  
heights from 200 t o  1000 km according t o  the Harris-Priester 
models f o r  4:OO and 14:OO hours loca l  time ( thick l i n e s )  and 
accourding t o  Nicolet 's model ( th in  l i n e ) .  
b 
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200 
s= 200 OBS. 
F=2m KI NG-HELE 
FALL 1959 1958/59 
MAXDAY -58 
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Loo 600 km 
-12 
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S-150 OBS. 
KING-HELE 
-MAX.DAY 
- 0 -  MI N.N IGHT 43-0- 
200 LOO 600 km 
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200 LOO 600 km 
-Z 
g cm-3 
s =loo 0 BS. 
F= 85 KING -HELE 
FALL 1962 1962 
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LOO 600 km 
-Z 
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1000 1400 1800 2200 'K 
T 


Relation between theoretical and observational models of the upper atmosphere

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