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Woo, R.

Publications and source records attributed to Woo, R..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Heliospheric Plasma Sheet and Coronal Streamers

In-situ measurements of solar wind plasma and magnetic field between 0.3 and 1 AU are used to investigate the structure of the heliospheric plasma sheet, namely the region of enhanced plasma density that surrounds the helioshperic current sheet.

solar wind↗
NASA NTRS1997

Origin of the Ubiquitous Fast Solar Wind

The solar wind is a direct manifestation of the coronal heating processes which continue to elude us. For over three decades, observations in interplanetary space have identified two types of wind: a slow component with highly variable physical properties also characterized by speeds typically beow 500 kn/s, and a much less variable fast wind flowing on average at 750 km/s1.

solar wind↗
NASA NTRS1997

Source Regions of the Slow Solar Wind

While the fast solar wind is generally thought to originate from coronal holes, the source of the slow solar wind is only known to be associated with the highly structured and highly variable streamer belt.

solar↗
NASA NTRS1996

Finest Filamentary Structures of the Corona in the Slow and Fast Solar Wind

Recent progress in our understanding of electron density fluctuations observed by radio occultation measurements has demonstrated that a break in the vicinity of 1 Hz in the temporal frequency spectrum of the density fluctuations provides a measure of the size of the finest filamentary structures in the solar corona.

interplanetary medium solar wind corona Sun occult↗
NASA NTRS1995

Probing the Solar Corona with Radio Ranging Measurements

An asymmetry in the radial variation of electron density above the east and west limbs of the Sun was inferred from centimeter wavelength ranging measurements conducted by Voyager 2 during its 1985 solar conjunction. The Voyager 2 ranging measurements are compared with the Mauna Loa Solar Observatory white-light coronagraph measurements of the underlying corona. Corona probing abilities are summarized.

sun solar corona radio ranging coronagraph white-l↗
NASA NTRS1995

Morphology of solar wind fluctuations and structure in the vicinity of the Sun from radio propagation measurements

Radio propagation measurements represent a powerful means for remote probing of electron density and solar wind speed in the acceleration region of the solar wind not yet explored by in situ measurements. Recent investigations based on radio propagation measurements have led to considerable progress in our knowledge of the general morphology of solar wind fluctuations and structure, especially in terms of their relationship to solar wind properties that have been observed directly by fields and particles measurements, and to coronal features observed in white-light measurements. The purpose of this paper is to present an overview of the latest results on quasi-stationary structure covering the large scale variation of solar wind speed over the streamer belt and coronal hole regions, coronal streamers (source of slow solar wind) and their associated small-scale electron density structure, plumes, density and fractional or relative density fluctuations, and the spectral characteristics of the electron density fluctuations. The radio propagation measurements not only reveal new information on the structure near the Sun, but also show that the structure appears to undergo substantial evolution on its way to 0.3 AU, the closest radial distance for which direct in situ spacecraft measurements are available.

Woo, R.↗
NASA NTRS1995

Density fluctuations in solar wind flow types at 1 AU: Comparison to Doppler scintillation measurements

Density fluctuations with periods 10 minutes to 1 hour have been investigated in ISEE 3 plasma measurements of solar wind flows at l AU. Coronal hole, interstream, plasma sheet, coronal mass ejection, and interaction region flow types are considered. The ISEE 3 results support the interpretation of the large-scale variations in density fluctuations observed by Doppler scintillation measurement techniques inside 0.2 AU. The highest absolute and relative density fluctuations occur ahead of and within the plasma from coronal mass ejections, with the maximum values occurring between the associated interplanetary shocks and the driver gas. For the quasi-stationary solar wind, density and relative density fluctuations are highest around the heliospheric current sheet and lowest in the high-speed coronal flow. Superposed epoch analysis shows that the region of enhanced density fluctuations and its abrupt boundaries observed in the vicinity of the heliospheric current sheet near the Sun persists to l AU, providing further support for the filamentary nature of the extensions of coronal streamers. The results of this study confirm the advantages of using density fluctuations rather than density as a tracer of solar wind flows with differing origins at the Sun and as a detector of propagating interplanetary disturbances.

Huddleston, D. E.↗
NASA NTRS1995

Solar Wind Speed Structure in the Inner Corona at 3-12R(sub)O

Estimates of solar wind speed obtained by Armstrong et al. [1986] based on 1983 VLA multiple-station intensity scintillation measurements inside 12 R(sub)O have been compared with white light coronagraph measurements.

solar wind corona radio astronomy↗