Bibcode
Jimenez, A.
Bibliographical reference
Solar Physics (ISSN 0038-0938), vol. 152, no. 1, p. 319
Advertised on:
6
1994
Citations
0
Refereed citations
0
Description
Sine 1984, simultaneous observations of irradiance and velocity solar
acoustic modes, have been carried out by several authors in order to
measure the phase difference between irradiance and velocity modes.
Following the earliest observations with a stratospheric balloon
(Frolich and van Der Raay, 1984), a two ground-based stations (Tenerife
and Baja, California) were established (Jimenez et al., 1990) obtaining
coherence results in the frequency range from 2.5 mHz to 4.3 mHz. These
phase differences between irradiance and velocity solar acoustic modes
are interpreted in terms of the non-adiabatic behavior of the solar
atmosphere. In 1988 the IPHIR (Frolich et al., 1988) instrument flown on
the PHOBOS-2 mission to Mars and measured the solar irradiance during
150 consecutive days. The best velocity observations obtained in
Tenerife for this period were compared with IPHIR data to compute the
phase differences (Schrijver et al., 1991). The final conclusion is that
good agreement is attained between `space', `quasi-space' and `ground
observations' which yield a phase diffference of about -125 degrees in
the frequency range 2.5 mHz to 4.2 mHz, with a slight increase suggested
by the data running up to 4.6 mHz. The entire scientific community looks
forward to SOHO data, which will increase a great deal the quality of
helioseismology results. Concerning phase differences and gains between
intensity and velocity solar oscillations, we will have more raw
continuous data (GOLF, VIRGO and MDI) which will improve the accuracy of
the results, and we will probably be able to extend the results to low
and high frequencies and study `changes' with time. Other important
projects before the launch of SOHO are the SOVA experiment (EURECA
satellite), which is now in the space and the DIFOS experiment on board
the CORONAS satellite which will be launched in autumn 1993. These
irradiance data together with ground-based velocity data will offer a
good opportunity to improve current results.