861 research outputs found
Comparison of Ground- and Space-based Longitudinal Magnetograms
We compare photospheric line-of-sight magnetograms from the Synoptic
Long-term Investigations of the Sun (SOLIS) vector spectromagnetograph (VSM)
instrument with observations from the 150-foot Solar Tower at Mt. Wilson (MWO),
Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), and
Michelson Doppler Imager (MDI) on Solar and Heliospheric Observatory (SOHO). We
find very good agreement between VSM and the other data sources for both
disk-averaged flux densities and pixel-by-pixel measurements. We show that the
VSM mean flux density time series is of consistently high signal-to-noise with
no significant zero-offsets. We discuss in detail some of the factors -spatial
resolution, flux dependence and position on the solar disk- affecting the
determination of scaling between VSM and SOHO/MDI or SDO/HMI magnetograms. The
VSM flux densities agree well with spatially smoothed data from MDI and HMI,
although the scaling factors show clear dependence on flux density. The factor
to convert VSM to HMI increases with increasing flux density (from 1
to 1.5). The nonlinearity is smaller for the VSM vs. ~SOHO/MDI scaling
factor (from 1 to 1.2).Comment: Accepted for publication in Solar Physic
Correlation Between Sunspot Number and ca II K Emission Index
Long-term synoptic observations in the resonance line of Ca II K constitute a
fundamental database for a variety of retrospective analyses of the state of
the solar magnetism. Synoptic Ca II K observations began in late 1904 at the
Kodaikanal Observatory, in India. In early 1970s, the National Solar
Observatory (NSO) at Sacramento Peak (USA) started a new program of daily
Sun-as-a-star observations in the Ca II K line. Today the NSO is continuing
these observations through its Synoptic Optical Long-term Investigations of the
Sun (SOLIS) facility. These different data sets can be combined into a single
disk-integrated Ca II K index time series that describes the average properties
of the chromospheric emission over several solar cycles. We present such a Ca
II K composite and discuss its correlation with the new entirely revised
sunspot number data series. For this preliminary investigation, the scaling
factor between pairs of time series was determined assuming a simple linear
model for the relationship between the monthly mean values during the duration
of overlapping observations.Comment: 16 pages, 8 figures, accepted for publication in Solar Physic
Fiscal Situation and Stabilization Fund of Buenos Aires City: evolution and forecast
After a period of positive fiscal results during years 2003 to 2005, the City of Buenos Aires faces challenges in its fiscal situation as of year 2006, which surely will be reflected in exercise 2007. During the period the 2003- 2005 City accumulated positive financial results near 418 million, they were destined to the Stabilization Fund created in 2003 by Decree of the Executive authority. The estimations made by the Executive authority on the closing of exercise 2006 at the time of presenting the Project of Budget 2007 show a negative result of -$1,096 million, the contained negative result in Budget 2007 bases similar originally elevated by the Executive to the Legislature, and later modified in the parliamentary approval. As opposed to an electoral year, where the pressures on the public expenditure usually increase, it is precise to strengthening the institutionalization and transparency of the Buenos Aires City Stabilization Fund.Fiscal Policy-Stabilization Fund-Budget Process-Legislature
Interpretation of Solar Magnetic Field Strength Observations
This study based on longitudinal Zeeman effect magnetograms and spectral line
scans investigates the dependence of solar surface magnetic fields on the
spectral line used and the way the line is sampled in order to estimate the
magnetic flux emerging above the solar atmosphere and penetrating to the corona
from magnetograms of the Mt. Wilson 150-foot tower synoptic program (MWO). We
have compared the synoptic program \lambda5250\AA line of Fe I to the line of
Fe I at \lambda5233\AA since this latter line has a broad shape with a profile
that is nearly linear over a large portion of its wings. The present study uses
five pairs of sampling points on the \AA line. We recommend
adoption of the field determined with a line bisector method with a sampling
point as close as possible to the line core as the best estimate of the
emergent photospheric flux. The combination of the line profile measurements
and the cross-correlation of fields measured simultaneously with \lambda5250\AA
and \lambda5233\AA yields a formula for the scale factor 1/\delta that
multiplies the MWO synoptic magnetic fields. The new calibration shows that
magnetic fields measured by the MDI system on the SOHO spacecraft are equal to
0.619+/-0.018 times the true value at a center-to-limb position 30 deg. Berger
and Lites (2003) found this factor to be 0.64+/-0.013 based on a comparison the
the Advanced Stokes Polarimeter.Comment: Accepted by Solar Physic
Random Lag Singular Cross-Spectrum Analysis
In a previous paper (Varadi et al., 1999), Random Lag Singular Spectrum
Analysis was offered as a tool to find oscillations in very noisy and long time
series. This work presents a generalization of the technique to search for
common oscillations in two or more time series.Comment: 8 pages + 1 figure (eps), Macro: AASTe
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