Incoherent backscatter observations of F region during solar eclips

Farley, D. T.

Green, J. L.

Mc Clure, J. P.

Peterson, V. L.

Sterling, D. L.

Van Zandt, T. E.

English

NASA Technical Reports Server

Incoherent Backscatter Observations of the F Region
 
during the NoveTlber 12, 1966 Solar Eclipse 
V. L. Peterson, D. T. Farley, J. L. Green, J. P. McClure 
D. L. Sterling) and T. E. Varzandt
 
/ 
Jicamarca Radar Observatory*_ 
Apartado 3747, L-ma, Peru 
"A cooperative project of the Institute for Telcco~mmunication Sciences 
and Aeronoy, arta! Science Sarvices Administration, Boulder, 
Colorado and the Instituto Geofis..me, da Peru, Lios Peru 
NATIONAL TECHNICA 
NFOMATION SERVICE 
U- " DERTMENT OF 
https://ntrs.nasa.gov/search.jsp?R=19680018211 2020-03-12T10:43:20+00:00Z
Simultaneous measurements of electrol 
concentration (N) from 150 to ?50 km and 
electroa temperature (T ) from 150 to 550 V 
'km were made om the Jgcamarca Radar Ob­
servatory during the November 12, 1966 1 
eclipse. Jicamarca was favorably placed
 
in that it lay within the path of ground
 
totality as well as being nearly on the
 
magnetic dip equator. The measurements
 
were made continuously using 5 minute in-'
 
tegrations with a 25 km height resolution.
 
The upper and lower 50 km of the two height1
 
ranges were often too noisy to be useful;,
 
accordingly, the following discussion is 
restricted to heights of 200 km and above 
Before the eclipse, both the N and 
Te profiles were normal, with a peak of Ni 
at about 325 km and a peak of T at about 
250 km. During the eclipse theeF2 layer 
moved upwards with an apparent velocity o; 
about 50 m/sec. Near totality an eclipse ! 
F1.5 layer formed in the F1 region. It 
increased-in height and density until by i
 
the end of the eclipse it had assumed the i
 
role of the normal P2 liyer. Thus, during
 
the second half of the eclipse there were!
 
two peaks of ionization in the F region, !
 
separated by a deep valley. - I
 
As the Fi.5layer started to form, I 
the Te peak first broadened, then moved 
npward with the valley beteen the £1.5 
and F2 layers, and finally split into two[ 
peaks, The lower peak assumed a height 
near 250 km while the upper peak continuej 
to move upward with the Fl.3-F2 valley and 
finally lost its identity upon reaching a 
height of about 500 km. 
Analysis has shown that below 300 km 
the variations in N were controlled pre­
dominantly by the normal production and 
loss mcchaniss. The derived parameters 
are of the ezpected magnitudeq; for ex­
ample, at 26q kn P 10 3zo and q 
750 cm sec .. in the 240-290 k hoightjj 
ranse the linear form of the loss equatio 
is valid, whereas in the 200-230 km range 
the trannition form must be used. 
 1 
Above 300 km vertical drift of the
 
electrons becomes increasingly important,
 
and above 350 km it is the coatrolling
 
factor for the electron distribution.
 
Preliminary analysis shows that the 
behavior of T is consistent with the 
theory of electron heating by elastic 
collisions with fast ohotoelectrons and 
coolin.g by collisions with ions and neu­
tral particles. An attempt is being made!
 
to evaluate the heat production function
 
and relate it to the electron production
 
function determined from the N analysis.
 
The T data also show that the neutrdl
 
temperature decreased by about 100 K dur­
ing the eclipse,
 



Incoherent backscatter observations of the F region during the November 12, 1966 solar eclipse

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server