SH13A-1093
Multi-scale Tools for Solar Image Processing
The important information contained in solar image data exists on many different time and spatial scales. This makes multi-scale transforms such as wavelets and curvelets very appropriate tools. These and other multi- scale transforms are used in several different types of image processing including image enhancement, feature detection, deconvolution and noise reduction. We present an overview of multi-scale transforms and show some of their applications to solar image data.
SH13A-1094
Correlation of multi-resolution analyses of active region magnetic field structure with flare activity
Two multi-resolution analyses are used to decompose active region magnetic fields into objects of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Lines separating opposite polarity groupings of flux at different lengthscales are found (a generalization of the notion of a magnetic neutral line). It is shown that the average magnetic field gradient for alpha, beta, beta-gamma, and beta-gamma-delta active regions increases in the order listed, and that the order is maintained over all length-scales. Since magnetic field gradient is strongly linked to active region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all lengthscales in the active region, and not just those lengthscales at which the strongest field gradients are found. Properties of these generalized neutral lines are also correlated with GOES flare activity in a search for an indicator of flare activity.
SH13A-1095
Nonlinear Force-Free Field Extrapolation of NOAA AR 0696
We investigate the 3D coronal magnetic field structure of NOAA AR 0696 in the period of November 09-11, 2004, before and after an X2.5 flare (occurring around 02:13 UT on November 10, 2004). The coronal magnetic field dominates the structure of the solar corona and consequently plays a key role for the understanding of the initiation of flares. The most accurate presently available method to derive the coronal magnetic field is currently the nonlinear force-free field extrapolation from measurements of the photospheric magnetic field vector. These vector-magnetograms were processed from stokes I, Q, U, and V measurements of the Big Bear Solar Observatory and extrapolated into the corona with the nonlinear force-free optimization code developed by Wiegelmann (2004). We analyze the corresponding time series of coronal equilibria regarding topology changes of the 3D coronal magnetic field during the flare. Furthermore, quantities such as the temporal evolution of the magnetic energy and helicity are computed.
SH13A-1096
Application of Statistical Image Segmentation to Recognition of Solar Magnetic Network
We have developed a statistical method for feature identification in NSO multidimensional imagery which requires a training set of independently determined image segmentations. The large spatial scale of our initial training set determined by the algorithm of Harvey and White (1999, ApJ 515, p. 812) mixes the details of magnetic network which are contained in the observations with quiet Sun and other features. We have found it difficult to reproduce this large scale in models of conditional and prior probabilities and are in fact interested in marking smaller scale structures for comparison with variation of total and spectral solar irradiance. We describe in this paper the performance of our technique with finer scale training sets determined by observations from other instruments and independently for the NSO data.
SH13A-1097
Two New Approaches to Determining Parameter Values to Emission Spectra From RHESSI
We examine two new approaches to determining parameter values to emission spectra from RHESSI. Simulated annealing removes much of the bias inherent in initializing commonly used deterministic routines through implementing a parameter space search minimizing a suitable cost function (such as sum of squares of differences between data and a parameterized curve). This search gradually moves from being a full random search to a directed search where only parameter values which minimize the cost function are accepted. In comparison, Markov Chain Monte Carlo methods are used to sample from the Bayesian posterior distribution constructed from prior information on the observation (such as the number of emission lines present and likely parameter values) as well as the data itself. Parameter values can then be assigned by constructing the appropriate averages from the data. These methods have the advantage of sidestepping many of the problems of traditional analysis routines (for example, ill-conditioned matrices) whilst allowing the easy inclusion of other information, such as parameter constraints. Both approaches are applied to RHESSI spectroscopic data, and are compared to more commonly used routines. RHESSI is comprised of separate detectors which allows us to conduct 9 independent measurements of the same solar flux over any time interval. Since these new methods return important information about the dispersion in a parameter from counting statistics, then the multi-detector sample will also contain important insight into the sources of systematic deviations.
SH13A-1098
Signatures of Magnetic Stress Prior to Three Solar Flares Observed by RHESSI
In order to better understand the location and evolution of magnetic reconnection, which is thought to be the energy release mechanism in solar flares, we combine the analysis of hard X-ray (HXR) sources observed by RHESSI with a three-dimensional, quantitative magnetic charge topology (MCT) model. We examine the location of reconnection by assuming a relationship between the build-up of energy in stressed coronal magnetic fields and the measurement of the change in separator flux per unit length. We find that the value of this quantity is larger on the separators that connect the HXR footpoint sources than the value on the separators that do not. Therefore, we conclude the MCT model gives useful insight into the relationship between sites of HXR emission and the topology of flare productive active regions. http://solar.physics.montana.edu/angela/
SH13A-1099
Methods of Detecting Polar Coronal Holes in the EUV
One method of forecasting the peak amplitude of future solar cycles uses the polar magnetic field strength at solar minimum to predict the value of the upcoming maximum. Because the polar field is closely related to the polar coronal hole, we would like to consider the size and shape of the polar hole on the prediction. We measure the perimeter of polar coronal holes over solar cycle 23 as they appear on the limb of the sun in 171, 195, and 304 Å\ solar images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO. The area within the perimeter can easily be determined. Taking measurements on the limb minimizes the effects of differences in scale height between the material emitting the various wavelengths. Perimeter tracking also allows for the coronal rotation rate to emerge organically from the data rather than forcing a period on the data. This method should help to improve our estimates of the size and shape of the polar coronal holes.
SH13A-1100
Variability of Solar Irradiances Using Wavelet Analysis
We have used wavelets to analyze the sunspot number, F10.7 (the solar irradiance at a wavelength of 10.7~cm), and Ap (a geomagnetic activity index). Three different wavelets are compared, showing how each selects either temporal or scale resolution. Our goal is an envelope of solar activity that better bounds the large amplitude fluctuations form solar minimum to maximum. We show how the 11-year cycle does not disappear at solar minimum, that minimum is only the other part of the solar cycle. Power in the fluctuations of solar-activity-related indices may peak during solar maximum but the solar cycle itself is always present. The Ap index has a peak after solar maximum that appears to be better correlated with the current solar cycle than with the following cycle.
SH13A-1101
Distinguishing non- stationarity from finite interval effects in the intermittent solar wind.
The solar wind flow has a magnetic Reynolds number estimated ~ 105 and fluctuations in solar wind bulk plasma parameters typically show a clear region of power law scaling in the power spectrum with an exponent close to -5/3. Quantitative analysis of solar wind fluctuations are thus often performed in the context of intermittent turbulence and center around methods to quantify statistical scaling, such as generalized structure functions which assume a weakly stationary process. The solar wind exhibits large scale secular changes and so the question arises as to whether the timeseries of the fluctuations is non- stationary. One approach is to seek a local stationarity by restricting the time interval over which statistical analysis is performed. However multifractality implies that the scaling exponents are local in time. Computing scaling exponents over different intervals of a stationary multifractal process can thus potentially yield anomalously time varying values for the scaling exponents, suggestive of non stationarity. We investigate this using synthetic datasets generated from a (self affine) Levy flight and from a (multifractal) p- model. We are able to estimate the minimum interval (number of datapoints) needed to quantify the scaling exponents in a stationary multifractal process. With fewer datapoints the stationary timeseries becomes indistinguishable from a nonstationary process and we illustrate this with nonstationary synthetic datasets. Finally we apply these ideas to in- situ solar wind observations.
SH13A-1102
Detection of the high energy solar protons by the particle detectors of Aragats Space- Environmental Center at 20 January 2005; Estimation of the significance of the peaks in the time–series.
On January 20, 2005, 7:02-7:05 UT the Aragats Multidirectional Muon Monitor (AMMM) located at 3200 m a.s.l. registered enhancement of the high energy secondary muon flux (threshold 5 GeV). The enhancement, lasting for three minutes, has statistical significance of ~4σ and is related to the X7.1 flare seen by the GOES, and very fast (2500 km/s) CME seen by SOHO, and the Ground Level Enhancements (GLE) N 69 detected by the world-wide network of neutron monitors and muon detectors. The energetic and temporal characteristics of the muon signal from the AMMM are compared with the characteristics of other monitors located at the Aragats Space-Environmental Center (ASEC) and with other neutron and muon detectors. Since secondary muons with energies above 5 GeV are corresponding to solar proton primaries with energies 20-30 GeV we conclude that in the episode of the particle acceleration at 7:02 – 7:05 UT 20 January 2005 solar protons were accelerated up to energies in excess of 20 GeV. To prove that detected peaks in the time-series are not only background flux (Galactic Cosmic Rays) fluctuations, but signal candidate (Solar Cosmic Rays), we perform additional investigations of the detectors count rates at 20 January. When calculated the chance probability we have to take into account the experimental procedures we use to reveal the signal. We made 3-minute time series from the 1 minute ones. The re-binning of time series is ordinary operation used by the all groups running the particle solar monitors. However, it has to be taken into account in calculating of the chance probability. Different attempts to obtain "best signal" considering different re- binning cannot be treated by standard Gaussian distribution, but can be considered by implementing Chapman statistics. To check this assumption and demonstrate the influence of the re-binning procedure we perform simulations with simple model of time series. Our numerical modeling confirm that when testing different data binning the probability of obtaining "fake" signal during a given time period increases proportional to number of tests and should be corrected with tuning of parameters of Chapman statistics. Simple Gaussian statistics gives positively biased estimates of chance probability.
SH13A-1103
Technique of Measuring Taylor Microscale
We present the method to measure Taylor microscale from the discrete data which is useful for the data from the spacecraft. To study how well the method works, we construct the discrete data from known power spectrum. We model the power spectrum as the frequency in inertial range is proportional to -5/3 slope and the power law index q at dissipation range can be varied. From the data, we compute the second order structure function and correlation function. To obtain the Taylor microscale, we use the technique of the Richardson extrapolation from parabolic fitting of the correlation function. We found that the error of Taylor microscale depend on the steepening at the dissipation range and the resolution of the data. Since in this study we can compute the solution of the Taylor microscale from each spectrum, we produce the correction ratio to help correcting the Taylor microscale from extrapolation method. Finally, we apply this technique to the magnetic field data from the spacecraft in the solar wind.
SH13A-1104
SOLIS: status, data products & science
The SOLIS project is currently operating two instruments, the Vector Spectromagnetograph (VSM) and the Integrated Sunlight Spectrometer (ISS). A third instrument, the Full Disk Patrol (FDP), is expected to be installed during 2008. Solar area-scans and full-disk photospheric and chromospheric longitudinal magnetograms are recorded daily as part of the VSM nominal observing program. Since August 2003, the VSM has recorded full-disk photospheric vector magnetograms at least weekly and, since November 2006, area-scans of active regions daily. Quick-look vector magnetic FITS formatted data and JPEG images are publicly available daily. In the near future, a typical VSM observing day will include three full-disk photospheric vector magnetograms. Carrington rotation and daily synoptic maps are also available from the photospheric magnetograms and coronal hole estimate images. In addition, calibrated ISS spectra are available as both FITS formatted data and JPEG image files. Also, Ca II K-line parameter time series data are available publicly as text formatted data and JPEG image files. These synoptic products, along with recent science results, will be summarized in this presentation. The SOLIS synoptic products are available at: http://solis.nso.edu/. SOLIS VSM data used here are produced cooperatively by NSF/NSO and NASA/LWS. The NSO is operated by AURA, Inc. under a cooperative agreement with the NSF. http://solis.nso.edu
SH13A-1105
SORCE Solar Irradiance Data Products
The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado manages the SOlar Radiation and Climate Experiment (SORCE) Science Data System. This data processing system routinely produces Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI) data products, which are formulated using measurements from the four primary instruments on board the SORCE spacecraft. The TIM instrument provides measurements of the TSI, whereas the SIM, SOLSTICE, and XPS instruments collectively provide measurements of the solar irradiance spectrum from 1 nm to 2400 nm (excluding 31-115nm, which is measured by the SEE instrument on NASA's TIMED mission). The SORCE Science Data System utilizes raw spacecraft and instrument telemetry, calibration data, and other ancillary information to produce a variety of solar irradiance data products that have been corrected for all known instrumental and operational factors. Since launch of the SORCE spacecraft in January 2003, science processing algorithms have continued to mature, and "Level 3" data products (time-averaged and/or spectrally resampled onto uniform wavelength scales) are routinely being produced and delivered to the public via the SORCE web site, and are archived at the Goddard Earth Sciences (GES) Data and Information Services Center (DISC, formerly DAAC). This poster provides an overview of the SORCE data processing system, summarizes the present state of the processing algorithms and future plans, describes the quality of the current SORCE data products, and provides details on how to access SORCE science data. http://lasp.colorado.edu/sorce
SH13A-1106
Data Management for the IHY-in-Africa Space Weather Program
During the past year an international group of scientists has been working towards coordinating space science activities in Africa. The intent of the IHY-in-Africa consortium is to increase the observational infrastructure in the African sector and leverage activities in other disciplines, in order to address compelling science questions under the IHY umbrella. Several GPS and magnetometer observing sites have already been secured and instruments are being deployed in African universities. Through the IHY framework, we propose to leverage GPS and magnetometer observations in the region by coordinating data acquisition, distribution, and research, and actively partnering with other disciplines. In particular, we seek to coordinate the new observations in Africa by establishing an IHY-in-Africa database, organize Space Weather Workshops in Sub-Saharan Africa in 2007 and 2009, and perform mid- and low- latitude ionospheric research in collaboration with scientists in African universities and our international collaborators. The NOAA National Geophysical Data Center (NGDC) will be the central repository for Africa-in IHY datasets and will provide access to these data for IHY-in-Africa scientists and collaborators. Existing tools within the data center will be used for data presentation and dissemination. http://www.spidr.ngdc.noaa.gov
SH13A-1107
Segmentation of SoHO/EIT Images using fuzzy clustering algorithms
The study of the variability of the solar corona and the monitoring of its traditional regions (Coronal Holes, Quiet Sun and Active Regions) are of great importance in astrophysics as well as in view of the Space Weather and Space Climate applications. In this presentation, I will propose a multi-channel unsupervised spatially- constrained fuzzy clustering algorithm that automatically segments EUV solar images into Coronal Holes, Quiet Sun and Active Regions. The use of Fuzzy logic allows to manage the various noises present in the images and the imprecision in the definition of the above mentioned regions. The process is fast and automatic. It is applied to SoHO-EIT images taken from January 1997 till May 2005, spanning thus almost a full solar cycle. Results in terms of areas and intensity estimations are consistent with previous knowledge. The method reveal the rotational and other mid-term periodicities in the extracted time series across solar cycle 23. Further, such an approach paves the way to bridging observations between spatially resolved data from imaging telescopes and time series from radiometers. Time series resulting form the segmentation of EUV coronal images can indeed provide an essential component in the process of reconstructing the solar spectrum.
SH13A-1108
Sunspot Numbers and Sunspot Irradiance Reductions as Obtained with OSPAN Semi- automatic Analysis
The USAF/AFRL Optical Solar PAtrol Network telescope (OSPAN) acquires true continuum solar images (0.08 Å bandwidth) in the optical region(6303.15 Å). OSPAN analysis software includes semi-automatic routines for measuring (1) sunspot counts, which we compare with counts obtained by traditional methods, and (2) solar irradiance reductions due tosunspot blocking. We present measurements of the variation of irradiance reductions as a function of the solar cycle, including examples of irradiance reduction due to sunspot activity during solarcycle maximum. This work was supported by US Air Force Office of Scientific Research (AFOSR).
SH13A-1109
Origins of the Wolf Sunspot Number Series: Geomagnetic Underpinning
The Wolf or International sunspot number (SSN) series is based on the work of Swiss astronomer Rudolf Wolf (1816-1893). Following the discovery of the sunspot cycle by Schwabe in 1843, Wolf culled sunspot counts from journals and observatory reports and combined them with his own observations to produce a SSN series that extended from 1700-1893. Thereafter the SSN record has been maintained by the Zurich Observatory and, since 1981, by the Royal Observatory of Belgium. The 1700-1893 SSN record constructed by Wolf has not been modified since his death. Here we show that Wolf's SSNs were not based solely on reports of sunspots but were calibrated by reference to geomagnetic range observations which closely track the sunspot number. Nor were these corrections small; for example Wolf multiplied the long series (1749-1796) of sunspot counts obtained by Staudacher by factors of 2.0 and 1.25, in turn, to obtain the numbers in use today. It is not surprising then that a competing SSN series obtained by Hoyt and Schatten based on group sunspot numbers is different, generally lower than that of Wolf. Comparison of the International number with current magnetic range observations indicates that, as Wolf found, the magnetic range (specifically, the average annual Y-component of mid-latitude stations) can be used as an independent check on the validity and stability of the SSN series. Moreover, the geomagnetic range series, which in itself is a long-term proxy of solar EUV emission, can be used to resolve discrepancies between the Wolf and Group SSN series during the 19th century.
SH13A-1110
Testing a possible scenario for delta-spot formation
δ-spot active regions are frequently interpreted as loops of magnetic flux which are strongly twisted. Could these twisted active-region field configurations arise from flux loops that originate from regions of the tachocline (the interface layer between the convection zone and radiative zone) that are strongly sheared by differential rotation? Helioseismic rotation inversions show that the tachocline displays a strong radial shear in the rotation rate at latitudes significantly less than 30 degrees. In addition, they show that the surface variation of differential rotation with latitude persists throughout the convection zone and into the tachocline. In many recent solar cycle dynamo models, most of the magnetic flux participating in the dynamo lies in the tachocline near the base of the solar convection zone. In some of these models, amplification of solar magnetic field from the poloidal (N-S) directions into the toroidal component (E-W direction) occurs primarily from the variation of the solar rotation rate with solar latitude, rather than with depth. In any case, the combination of radial and latitude dependent rotation rate results in shearing motions which may not only stretch magnetic field lines in the tachocline, but may shear them as well, especially at low latitudes. This shearing motion is a potential candidate for generating twisted magnetic field configurations that rise to the photosphere. This leads us to ask the question: Is there a preference for the formation of δ-spot active regions at low latitude? In this poster, we investigate this question observationally, by comparing the latitude distribution of δ-spot active regions with the the distribution of all active regions, most of which do not display strong twist. We show the butterfly diagram of all active regions, just δ-spot regions, and compare and contrast the distribution of the two active region samples with time and latitude. We will use these data to test the hypothesis that δ-spot regions form preferentially at low latitudes, compared to the sample of all active regions.
SH13A-1111
Properties of Hot Spots for Solar Activity
Hot spots for solar flares are areas of enhanced flare activity in a long term, which rotate rigidly at a certain rate. For example, a double-hot-spot system with a synodic period of 26.73 days persisted for three solar cycles (20 through 22) in the same locations in the northern hemisphere. This paper investigates properties of three hot- spot systems. The first is mentioned above, and the second is a double-hot-spot system with a synodic rotation period of 27.41 days, which operated in the northern hemisphere during cycles 19, 20, and 21. The third one is a double-hot-spot system with a synodic rotation period of 28.24 days, which operated in the southern hemisphere during solar cycle 23. This system was discovered by Bai (2003, ApJ 585, 1114), by analyzing flares observed until June 2002. Analysis of flares observed since then shows that this system operated until the end of January 2004, after which it ceased to operate. A double-hot-spot system has two hot spots, separated by about 180 degrees in longitude, with the same rotation period. The three hot-spot systems show different properties. The 26.73-day hot-spot system mainly influenced distributions of flares from superactive regions, whereas the distribution of flares produced by active regions with three or less major flares did not show a hint of this hot-spot system. On the other hand, for the other two hot-spot systems, distributions of flares from ordinary active regions (with three or less major flares) were also influenced by hot spots. Another interesting discovery is that the two hot spots with the 26.73-day period were not active simultaneously. When one hot spot was active, the other was dormant, and vice versa. Even for a long interval, their activity levels were anti-correlated.
SH13A-1112
Preliminary Results of a Study of Rotating Sunspots in Active Regions Utilizing SOHO/MDI Magnetograms During the Solar Maximum in Cycle 23
As part of a statistical study of sunspots that rotate about their umbral centers in active regions, we have begun to analyze SOHO/MDI full-disk, synoptic magnetogram movies on a daily basis during solar maximum in cycle 23. We are analyzing these active regions when they are least distorted, within approximately +/- 30 degrees longitude of disk center. Many such active regions containing rotating sunspots have been identified. For example, our preliminary study found such active regions near disk center with one or more rotating sunspots for approximately two-thirds of the days in year 2000. Rotating sunspots result from looking temporally at perpendicular slices of a large, twisted magnetic flux tube penetrating through the photosphere from below the solar surface out into the solar corona. The twisted tube, or loop, carries energy via the Poynting flux density up into the corona, where some or all of the energy may be stored in the non-potentiality of the magnetic field to empower flares and coronal mass ejections. Coupling these findings of the presence of rotating sunspots on a majority of days during solar maximum with those from previous studies showing rotating sunspots associated with almost all of the X-flares since April 1998, and many of the M-flares, suggests that rotating sunspots could be providing much of the energy needed by the multitude of large X-ray flares occurring during the solar maximum period. Preliminary results of this study to date will be presented. This work was supported by NASA under the TRACE contract NAS5-38099.