 |
| Titel |
Statistics of 150-km echoes over Jicamarca based on low-power VHF observations |
| VerfasserIn |
J. L. Chau, E. Kudeki |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 24, no. 5 ; Nr. 24, no. 5 (2006-07-03), S.1305-1310 |
| Datensatznummer |
250015547
|
| Publikation (Nr.) |
 copernicus.org/angeo-24-1305-2006.pdf |
|
|
|
|
|
| Zusammenfassung |
| In this work we summarize the statistics of the so-called 150-km
echoes obtained with a low-power VHF radar operation at the Jicamarca
Radio Observatory (11.97 S, 76.87 W, and 1.3
dip angle at 150-km altitude) in Peru. Our results are based on almost
four years of observations between August 2001 and July 2005
(approximately 150 days per year). The majority of the observations
have been conducted between 08:00 and 17:00 LT. We present
the statistics of occurrence of the echoes for each of the four seasons as a
function of time of day and altitude. The occurrence frequency of the
echoes is ~75% around noon and start decreasing
after 15:00 LT and disappear after 17:00 LT in all seasons. As
shown in previous campaign observations, the 150-echoes appear at a
higher altitude (>150 km) in narrow layers in the morning, reaching lower
altitudes (~135 km) around noon, and disappear at higher
altitudes (>150 km) after 17:00 LT. We show that although
150-km echoes are observed all year long, they exhibit a
clear seasonal variability on altitudinal coverage and the percentage of
occurrence around noon and early in the morning. We also show
that there is a strong day-to-day variability, and no correlation
with magnetic activity. Although our results do not solve the
150-km riddle, they should be taken into account when a reasonable
theory is proposed. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|