Radio Measurements of the Height of Strong Coronal Magnetic Fields Above Sunspots at the Solar Limb

We measure coronal magnetic field strengths of 1750 G at a height of 8000 km above a large sunspot in NOAA AR 10652 at the west solar limb on 2004 July 29 using coordinated observations with the Very Large Array, the Transition Region and Coronal Explorer , and three instruments (CDS, EIT, MDI) aboard the Solar and Heliospheric Observatory . This observation is the first time that coronal radio brightness temperatures have been analyzed in a 15 GHz solar radio source projected above the limb. Observations at 8 GHz yield coronal magnetic field strengths of 960 G at a height of 12,000 km. The field strength measurements combine to yield a magnetic scale height km. The radio brightness temperature maxima are located away from a sunspot L p 6900 B plume that appears bright in EUV line emission formed at temperatures around several #105 K. We use the density-sensitive emission-line intensity ratio of O iv 625.8 /554.5 to derive an electron density (in units ûû AA ne of cm3) of at the base of the plume. log n p 10.1 0.2 e