Related papers: Testing the flux tube expansion factor -- solar wi…
The solar wind speed at 1 AU shows variations in latitude and in time which reflect the evolution of the global background magnetic field during the activity cycle. It is commonly accepted that the terminal wind speed in a magnetic…
Empirical solar wind speed models play an important role in enabling space weather forecasting with low computational cost. Among these, one model called WS model is based on the asymptotic expansion factor. However, it is known that it…
For the past 30+ years, the magnetic expansion factor ($f_s$) has been used in empirical relationships to predict solar wind speed ($v_{obs}$) at 1 AU, based on an inverse relationship between these two quantities. Coronal unipolar…
The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-yr solar cycle. For instance, the wind terminal velocity is thought to be…
We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\mathrm{S}}$]) at all latitudes using data of…
By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et…
Both remote-sensing measurements using the interplanetary scintillation (IPS) technique and in situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions. At present what makes the…
The properties of the solar wind, as measured in situ throughout the heliosphere, depend both on the characteristics of its coronal source and on the intrinsic processes governing its interplanetary evolution. Recently, radial and Parker…
The potential field approximation has been providing a fast, and computationally inexpensive estimation for the solar corona's global magnetic field geometry for several decades. In contrast, more physics-based global magnetohydrodynamic…
The solar wind is connected to the Sun's atmosphere by flux tubes that are rooted in an ever-changing pattern of positive and negative magnetic polarities on the surface. Observations indicate that the magnetic field is filamentary and…
Context. The Sun's complex corona is the source of the solar wind and interplanetary magnetic field. While the large scale morphology is well understood, the impact of variations in coronal properties on the scale of a few degrees on…
The solar-wind energy flux measured near the ecliptic is known to be independent of the solar-wind speed. Using plasma data from Helios, Ulysses, and Wind covering a large range of latitudes and time, we show that the solar-wind energy flux…
By using our previous results of magnetohydrodynamical simulations for the solar wind from open flux tubes, I discuss how the solar wind in the past is different from the current solar wind. The simulations are performed in fixed…
Four decades have gone by since the discovery that the solar wind at 1 AU seems to exist in two relatively distinct states: slow and fast. There is still no universal agreement concerning the primary physical cause of this apparently…
Because of its distinctive compositional properties and variability, low-speed ($\lesssim 450$ km s$^{-1}$) solar wind is widely believed to originate from coronal streamers, unlike high-speed wind, which comes from coronal holes. An…
Solar wind back-mapping is a combination of ballistic mapping and magnetic mapping. By examining the different model ingredients that can affect the derived back-mapped position, we aim to provide a more precise estimate of the source…
Broadly, solar wind source regions can be classified by their magnetic topology as intermittently and continuously open to the heliosphere. Early models of solar wind acceleration do not account for the fastest, non-transient solar wind…
At present it remains to address why the fast solar wind is fast and the slow wind is slow. Recently we have shown that the field line curvature may substantially influence the wind speed $v$, thereby offering an explanation for the Arge et…
This paper reviews the current state of our understanding of high-speed solar wind acceleration in coronal holes. Observations by SOHO, coupled with interplanetary particle measurements going back several decades, have put strong…
In-situ measurements by several spacecraft have revealed that the solar wind is frequently perturbed by transient structures (magnetic folds, jets, waves, flux-ropes) that propagate rapidly away from the Sun over large distances. Parker…