SWICS User Notes - Ulysses

SWICS - User Notes

SWICS Contact:

Dr. R. v. Steiger
International Space Science Institute
Hallerstrasse 6
CH-3012 Bern
Switzerland

Phone: (41) 31-631 4890
Telefax: (41) 31-631 4897

E-mail: vsteiger@issi.unibe.ch

Ulysses/SWICS Heavy Ion Composition Data: User's Recipe Thomas Zurbuchen and Rudolf von Steiger Updated 5-Aug-2011 General Composition: Composition observations are the most powerful technique for identifying the character of solar wind plasma streams. Plasma composition is determined close to the Sun, by plasma processes occurring in the upper chromosphere near the transition region (elemental composition), and by the temperature history of the plasma between the transition region and 3 solar radii (charge state composition). These plasma processes near the source differ markedly between the fast and the slow solar wind, and even larger differences, for example in the temperature histories, are observed in the case of coronal mass ejections (CMEs), The compositional data are particularly useful when we try to understand specific time periods with interacting solar wind streams such as CIRs and CMEs. Magnetic rotations, indicative of a magnetic cloud embedded inside a CME, generally occupy only a portion of the CME. The compositional data can be used to determine the full extent of the CME, and indeed is the only plasma parameter that can do so. Elemental composition signatures: Elemental composition varies according to the solar wind source. Elemental fractionation strongly depends on the First Ionization Potential (FIP) of the element. The smaller the FIP, the easier it is to ionize particles that can end up in the solar wind. Element ratios in the solar wind show a characteristic fractionation pattern when compared to solar abundance ratios: Elements with an FIP smaller than 10 eV are enriched in the solar wind by a factor that is indicative of the solar wind type, on average ~3 in the slow wind and ~1.5 in fast streams (von Steiger et al. 1997; 2000). The ratio Fe/O compares an element of very small FIP with a high-FIP element and thus is indicative of the strength of the FIP fractionation. Charge state composition signatures: Charge state composition results, such as from O, C, and Fe, contain a coronal "finger-print" of the solar wind source region and the expansion properties close to the Sun (see, e.g. BŸrgi and Geiss, 1986). During their expansion process from the coronal source, the ionic charge state adapts to the environment until the recombination and ionization time-scale of a certain ionic charge state becomes large compared to the expansion time-scale. At this point, Rf, the respective charge state freezes in. For a given speed, temperature and density profile each ionic charge state has its own specific freeze- in point which may vary quite considerably from one ion species to another. It turns out that O7+/O6+, as well as C6+/C5+ freeze in rather close to the solar wind source region, and therefore show the most variability. The charge states of Fe freeze in further out, at up to 3.5 solar radii. It has been pointed out (see, e.g., Geiss et al., 1995; Von Steiger et al., 1997; 2000) that the charge state composition clearly distinguishes coronal hole associated solar wind from streamer-associated slow solar wind. Furthermore, clear variations within low-speed solar wind also separate different sources of low-speed solar wind (Zurbuchen et al., 2000). Finally, very high charge states, e.g. of Fe, are often indicative of CMEs. Description of archive parameters: a) Heavy ion main charge states (yearly files uswimatbYY.dat): Listed are density (relative to O6+) , speed, and kinetic temperature of the main charge state of heavy elements. They can be used to track the kinetic properties (differential speeds, mass- proportional temperatures) of these ions and their evolution with heliocentric distance, heliographic latitude, etc. They must not be used, however, to derive freeze-in temperatures or abundance ratios of elements (although the ratio C6+/O6+ is an excellent proxy for the C and O freezing-in temperature). b) Selected charge states and abundance ratios (yearly files uswichstYY.dat): - Alpha particle speed: Repeated from previous archive for comparison. - C6+/C5+ and O7+/O6+ ratios: These two ratios are essentially redundant, with the former being ~10 times higher than the latter on average. At high values the O ratio is more reliable (because C5+ is getting rare) whereas at low values the C ratio is preferable (because O7+ gets rare). Low ratios are indicative of fast streams. - Fe/O abundance ratio: This is a proxy for the strength of the FIP fractionation if divided by the solar Fe/O ratio of ~0.05. - Average charge state of Fe: Weighted average of all charge states from Fe6+ to Fe16+, normally between 9 and 12 both in slow and in fast wind. High values are a good CME indicator. - Number of instrument cycles that were accumulated to obtain the 3-hour average value. Each instrument cycle takes 13 minutes, so values of 12-14 are normal, whereas low values should be considered as a warning. Statistical accuracy of results: The data have been calculated using automatic routines as described in von Steiger et al. (2000). The accuracy of these data mostly depends on the counting statistics. Generally, the typical count rate is directly proportional to the solar wind mass flux. The statistical accuracy of these composition measurements is estimated to be 10- 25%. References: BŸrgi, A., and J. Geiss, Sol. Phys., 103, 347, 1986. Geiss, J., et al., Science, 268, 1033, 1995. Schwadron, N. A., L. A. Fisk, and T. H. Zurbuchen, Astrophys. J. , 521, 859, 1999. Von Steiger, R., J. Geiss, and G. Gloeckler, in Cosmic winds and the heliosphere, 581, Arizona Press, 1997. Von Steiger et al., J. Geophys. Res., 105, 27,217, 2000. Zurbuchen, T. H., et al., J. Geophys. Res., 105, 18,327, 2000. ________________________________________________________________________________ SWICS FILE FORMAT (REFERENCE: A&A,92,2 page 279, table 5) UDS REPRESENTATIVE: R. VON STEIGER (VSTEIGER@ISSIBERN.CH) Product 1: Heavy Ions Main Charge States (yearly files uswimatbYY.dat) RECORD FORMAT: C FREE FORMAT READ(1,*)IYEAR,IDOY,IHOUR,IMIN,ISEC, . DENS_ALPHA,VEL_ALPHA,TEMP_ALPHA, . DENS_C6,VEL_C6,TEMP_C6, . DENS_O6,VEL_O6,TEMP_O6, . DENS_NE8,VEL_NE8,TEMP_NE8, . DENS_MG10,VEL_MG10,TEMP_MG10, . DENS_SI9,VEL_SI9,TEMP_SI9, . DENS_S10,VEL_S10,TEMP_S10, . DENS_FE11,VEL_FE11,TEMP_FE11 C FIXED FORMAT READ(1,100)IYEAR,IDOY,IHOUR,IMIN,ISEC, . DENS_ALPHA,VEL_ALPHA,TEMP_ALPHA, . DENS_C6,VEL_C6,TEMP_C6, . DENS_O6,VEL_O6,TEMP_O6, . DENS_NE8,VEL_NE8,TEMP_NE8, . DENS_MG10,VEL_MG10,TEMP_MG10, . DENS_SI9,VEL_SI9,TEMP_SI9, . DENS_S10,VEL_S10,TEMP_S10, . DENS_FE11,VEL_FE11,TEMP_FE11 100 FORMAT(X,I4,X,I3,X,I2,2(X,2I2),8(E10.3,X,F6.1,E10.3)) PARAMETER LIST: IYEAR: year IDOY: day of year IHOUR: hour IMIN: minute ISEC: second DENS_ALPHA: alpha to oxygen 6+ density ratio VEL_ALPHA: alpha velocity TEMP_ALPHA: alpha temperature DENS_C6: carbon 6+ to oxygen 6+ density ratio VEL_C6: carbon 6+ velocity TEMP_C6: carbon 6+ temperature DENS_O6: oxygen 6+ density in cm^-3 VEL_O6: oxygen 6+ velocity TEMP_O6: oxygen 6+ temperature DENS_NE8: neon 8+ to oxygen 6+ density ratio VEL_NE8: neon 8+ velocity TEMP_NE8: neon 8+ temperature DENS_MG10: magnesium 10+ to oxygen 6+ density ratio VEL_MG10: magnesium 10+ velocity TEMP_MG10: magnesium 10+ temperature DENS_SI9: silicon 9+ to oxygen 6+ density ratio VEL_SI9: silicon 9+ velocity TEMP_SI9: silicon 9+ temperature DENS_S10: sulphur 10+ to oxygen 6+ density ratio VEL_S10: sulphur 10+ velocity TEMP_S10: sulphur 10+ temperature DENS_FE11: iron 11+ to oxygen 6+ density ratio VEL_FE11: iron 11+ velocity TEMP_FE11: iron 11+ temperature DENSITY UNITS: ratio to oxygen 6+ density (no units) VELOCITY UNITS: km/s TEMPERATURE UNITS: K TIME RESOLUTION: 3.0 hours; times indicate the beginning of the interval NOTES: All parameters values are positive definite; zeroes indicate missing values Product 2: Selected Charge State and Abundance Ratios (yearly files uswichstYY.dat) RECORD FORMAT: C FREE FORMAT READ(1,*)IYEAR,IDOY,IHOUR,IMIN,ISEC, . VEL_ALPHA, . RAT_C6_C5, . RAT_O7_O6, . RAT_FE_O, . CHARGE_FE, . N_CYC C FIXED FORMAT READ(1,100)IYEAR,IDOY,IHOUR,IMIN,ISEC, . VEL_ALPHA, . RAT_C6_C5, . RAT_O7_O6, . RAT_FE_O, . CHARGE_FE, . N_CYC 100 FORMAT(X,I4,X,I3,3(X,2I2),X,F6.1,3(X,F6.3),X,F4.1,X,I3) PARAMETER LIST: IYEAR: year IDOY: day of year IHOUR: hour IMIN: minute ISEC: second VEL_ALPHA: alpha velocity RAT_C6_C5: ratio of carbon 6+ to 5+ RAT_O7_O6: ratio of oxygen 7+ to 6+ RAT_FE_O: abundance ratio of iron to oxygen CHARGE_FE: average charge state of iron N_CYC: number of instrument cycles in average VELOCITY UNITS: km/s CHARGE UNITS: e = 1.6022E-19 C TIME RESOLUTION: 3.0 hours; times indicate the beginning of the interval NOTES: All parameters values are positive definite; zeroes indicate missing values