scholarly journals Characteristics and performances of an interferometric Doppler imager installed at the 188 cm telescope of Okayama Observatory

2020 ◽  
Author(s):  
François-Xavier Schmider ◽  
Julien Dejonghe ◽  
Tristan Guillot ◽  
Masahiro Ikoma ◽  
Patrick Boumier ◽  
...  
Keyword(s):  
Doppler Imager

scholarly journals EUV Line Intensities and the Magnetic Field in Solar Active Regions

2001 ◽  
Vol 203 ◽  
pp. 276-279
Author(s):  
J. Ireland ◽  
A. Fludra
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Active Regions ◽  
Central Meridian ◽  
Coronal Emission ◽  
Data Set ◽  
Line Intensities ◽  
Doppler Imager ◽  
Synoptic Observations ◽  
The Magnetic Field

The Coronal Diagnostic Spectrometer (CDS) on SOHO carries out daily synoptic observations of the Sun in four EUV (extreme ultraviolet) spectra: He I 584 Å, O V 630 Å, Mg IX 368 Å and Fe XVI 360 Å, over a 4 arcmin-wide strip along the solar central meridian. Using 53 active regions observed in this data set along with co-temporally observed SOHO-MDI (Michelson Doppler Imager) magnetograms we study the correlation of the chromospheric, transition region and coronal emission with the photospheric magnetic field for meridional active regions, probing the relation between the radiative output and magnetic observables. We also establish empirical, quantitative relations among intensities of different lines, and between intensities and the magnetic field flux.

scholarly journals Internal structure and rotation of the Sun: First results from the MDI data

1997 ◽  
Vol 181 ◽  
pp. 203-210
Author(s):  
A.G. Kosovichev ◽  
J. Schou ◽  
P.H. Scherrer ◽  
R.S. Bogart ◽  
R.I. Bush ◽  
...  
Keyword(s):  
Thin Layer ◽  
Spectral Lines ◽  
Convective Boundary ◽  
Doppler Imager ◽  
Lower Amplitude ◽  
Oscillation Modes ◽  
First Results ◽  
Sharp Variation ◽  
The Mean ◽  
Initial Results

The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.

scholarly journals Intra-seasonal Oscillations (ISO) of zonal-mean meridional winds and temperatures as measured by UARS

2005 ◽  
Vol 23 (4) ◽  
pp. 1131-1137 ◽  
Author(s):  
F. T. Huang ◽  
H. G. Mayr ◽  
C. A. Reber
Keyword(s):  
Meridional Wind ◽  
Mean Flow ◽  
Independent Evidence ◽  
Doppler Imager ◽  
Temperature Oscillations ◽  
Low Latitudes ◽  
Meridional Winds ◽  
Flow Interactions ◽  
Phase Variations ◽  
Seasonal Oscillations

Abstract. Based on an empirical analysis of measurements with the High Resolution Doppler Imager (HRDI) on the UARS spacecraft in the upper mesosphere (95km), persistent and regular intra-seasonal oscillations (ISO) with periods of about 2 to 4 months have recently been reported in the zonal-mean meridional winds. Similar oscillations have also been discussed independently in a modeling study, and they were attributed to wave-mean-flow interactions. The observed and modeled meridional wind ISOs were largely confined to low latitudes. We report here on an analysis of concurrent UARS temperature measurements, which produces oscillations similar to those seen in the meridional winds. Although the temperature oscillations are observed at lower altitudes (55km), their phase variations with latitude are qualitatively consistent with the inferred properties seen in the meridional winds and thus provide independent evidence for the existence of ISOs in the mesosphere.

scholarly journals Remote sensing of mesospheric winds with the high-resolution doppler imager

1992 ◽  
Vol 40 (12) ◽  
pp. 1599-1606 ◽  
Author(s):  
Paul B. Hays ◽  
HRDI Science Team
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Doppler Imager

scholarly journals The link between CME-associated dimmings and interplanetary magnetic clouds

2008 ◽  
Vol 4 (S257) ◽  
pp. 265-270 ◽  
Author(s):  
Cristina H. Mandrini ◽  
María S. Nakwacki ◽  
Gemma Attrill ◽  
Lidia van Driel-Gesztelyi ◽  
Sergio Dasso ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Large Scale ◽  
Extreme Ultraviolet ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Magnetic Structures ◽  
Doppler Imager ◽  
Imaging Telescope

AbstractCoronal dimmings often develop in the vicinity of erupting magnetic configurations. It has been suggested that they mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the ejected flux. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud (MC) to find clues about the origin of the ejected flux rope. In the context of this interpretation, we present several events for which we have done a comparative solar-interplanetary analysis. We combine SOHO/Extreme Ultraviolet Imaging Telescope (EIT) data and Michelson Doppler Imager (MDI) magnetic maps to identify and measure the flux in the dimmed regions. We model the associated MCs and compute their magnetic flux using in situ observations. We find that the magnetic fluxes in the dimmings and MCs are compatible in some events; though this is not the case for large-scale and intense eruptions that occur in regions that are not isolated from others. We conclude that, in these particular cases, a fraction of the dimmed regions can be formed by reconnection between the erupting field and the surrounding magnetic structures, via a stepping process that can also explain other CME associated events.

Diurnal migrating tide as seen by the high-resolution Doppler imager/UARS: 1. Monthly mean global meridional winds

1997 ◽  
Vol 102 (D4) ◽  
pp. 4405-4422 ◽  
Author(s):  
B. V. Khattatov ◽  
V. A. Yubin ◽  
M. A. Geller ◽  
P. B. Hays ◽  
R. A. Vincent
Keyword(s):  
High Resolution ◽  
Doppler Imager ◽  
Meridional Winds
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