Subsurface Meridional Flow from HMI Using the Ring-Diagram Pipeline

被引:25
作者
Komm, R. [1 ]
Hernandez, I. Gonzalez [1 ]
Hill, F. [1 ]
Bogart, R. [2 ]
Rabello-Soares, M. C. [2 ]
Haber, D. [3 ]
机构
[1] Natl Solar Observ, Tucson, AZ 85719 USA
[2] HEPL Stanford Univ, Stanford, CA USA
[3] JILA Univ Colorado, Boulder, CO USA
关键词
Helioseismology; observations; Velocity fields; interior; OSCILLATION NETWORK GROUP; FLUX-TRANSPORT DYNAMO; SOLAR ACTIVE REGIONS; CIRCULATION; MOTIONS; SUN;
D O I
10.1007/s11207-012-0073-y
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have determined the meridional flows in subsurface layers for 18 Carrington rotations (CR 2097 to 2114) analyzing high-resolution Dopplergrams obtained with the Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO). We are especially interested in flows at high latitudes up to 75(a similar to) in order to address the question whether the meridional flow remains poleward or reverses direction (so-called counter cells). The flows have been determined in depth from near-surface layers to about 16 Mm using the HMI ring-diagram pipeline. The measured meridional flows show systematic effects, such as a variation with the B (0)-angle and a variation with central meridian distance (CMD). These variations have been taken into account to lead to more reliable flow estimates at high latitudes. The corrected average meridional flow is poleward at most depths and latitudes with a maximum amplitude of about near 37.5(a similar to) latitude. The flows are more poleward on the equatorward side of the mean latitude of magnetic activity at 22(a similar to) and less poleward on the poleward side, which can be interpreted as convergent flows near the mean latitude of activity. The corrected meridional flow is poleward at all depths within +/- 67.5(a similar to) latitude. The corrected flow is equatorward only at 75(a similar to) latitude in the southern hemisphere at depths between about 4 and 8 Mm and at 75(a similar to) latitude in the northern hemisphere only when the B (0) angle is barely large enough to measure flows at this latitude. These counter cells are most likely the remains of an insufficiently corrected B (0)-angle variation and not of solar origin. Flow measurements and B (0)-angle corrections are difficult at the highest latitude because these flows are only determined during limited periods when the B (0) angle is sufficiently large.
引用
收藏
页码:85 / 106
页数:22
相关论文
共 34 条
[1]   CHARACTERISTICS OF SOLAR MERIDIONAL FLOWS DURING SOLAR CYCLE 23 [J].
Basu, Sarbani ;
Antia, H. M. .
ASTROPHYSICAL JOURNAL, 2010, 717 (01) :488-495
[2]   Effects of foreshortening on shallow sub-surface flows observed with local helioseismology [J].
Beckers, Jacques M. .
SOLAR PHYSICS, 2007, 240 (01) :3-7
[3]   HMI ring diagram analysis II. Data products [J].
Bogart, R. S. ;
Baldner, C. ;
Basu, S. ;
Haber, D. A. ;
Rabello-Soares, M. C. .
GONG-SOHO 24: A NEW ERA OF SEISMOLOGY OF THE SUN AND SOLAR-LIKE STARS, 2011, 271
[4]   HMI ring diagram analysis I. The processing pipeline [J].
Bogart, R. S. ;
Baldner, C. ;
Basu, S. ;
Haber, D. A. ;
Rabello-Soares, M. C. .
GONG-SOHO 24: A NEW ERA OF SEISMOLOGY OF THE SUN AND SOLAR-LIKE STARS, 2011, 271
[5]   LARGE-SCALE MOTIONS ON THE SUN - AN OVERVIEW [J].
BOGART, RS .
SOLAR PHYSICS, 1987, 110 (01) :23-34
[6]   A Babcock-Leighton flux transport dynamo with solar-like differential rotation [J].
Dikpati, M ;
Charbonneau, P .
ASTROPHYSICAL JOURNAL, 1999, 518 (01) :508-520
[7]  
Dikpati M., 2004, HELIO ASTEROSEISMOLO, P233
[8]   THEORY OF SOLAR MERIDIONAL CIRCULATION AT HIGH LATITUDES [J].
Dikpati, Mausumi ;
Gilman, Peter A. .
ASTROPHYSICAL JOURNAL, 2012, 746 (01)
[9]   POLAR FIELD PUZZLE: SOLUTIONS FROM FLUX-TRANSPORT DYNAMO AND SURFACE-TRANSPORT MODELS [J].
Dikpati, Mausumi .
ASTROPHYSICAL JOURNAL, 2011, 733 (02)
[10]   Impact of changes in the Sun's conveyor-belt on recent solar cycles [J].
Dikpati, Mausumi ;
Gilman, Peter A. ;
de Toma, Giuliana ;
Ulrich, Roger K. .
GEOPHYSICAL RESEARCH LETTERS, 2010, 37