English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We investigate the evolution of a well-observed, long-lived, low-latitudecoronal hole (CH) over 10 solar rotations in the year 2012. By combining EUVimagery from STEREO-A/B and SDO we are able to track and study the entireevolution of the CH having a continuous 360$\deg$ coverage of the Sun. Theremote sensing data are investigated together with in-situ solar wind plasmaand magnetic field measurements from STEREO-A/B, ACE and WIND. From this weobtain how different evolutionary states of the CH as observed in the solaratmosphere (changes in EUV intensity and area) affect the properties of theassociated high-speed stream measured at $1$AU. Most distinctly pronounced forthe CH area, three development phases are derived: a) growing, b) maximum, andc) decaying phase. During these phases the CH area a) increases over a durationof around three months from about $1 \cdot 10^{10} \mathrm{km}^{2}$ to $6 \cdot10^{10} \mathrm{km}^{2}$, b) keeps a rather constant area for about one monthof $> 9 \cdot 10^{10} \mathrm{km}^{2}$, and c) finally decreases in thefollowing three months below $1 \cdot 10^{10} \mathrm{km}^{2}$ until the CHcannot be identified anymore. The three phases manifest themselves also in theEUV intensity and in in-situ measured solar wind proton bulk velocity.Interestingly, the three phases are related to a different range in solar windspeed variations and we find for the growing phase a range of$460-600$~km~s$^{-1}$, for the maximum phase $600-720$~km~s$^{-1}$, and for thedecaying phase a more irregular behavior connected to slow and fast solar windspeed of $350-550$~km~s$^{-1}$.

3-Phase Evolution of a Coronal Hole, Part I: 360{\deg} remote sensing and in-situ observations