HAO 2011 Profiles In Science: Dr. Philip Judge

Contact:

Dr. Philip Judge is a Senior Scientist in the High Altitude Observatory. His research interests include MHD, spectroscopy and spectropolarimetry of the solar atmosphere, with emphasis on understanding the free energy available to the solar chromosphere and corona. From October 2010-2011 he has studied the relationship between thermal fine structure and magnetic fields in the solar atmosphere, the role of spicules in the solar atmosphere, variations of solar irradiance over centuries, and has pursued infrared spectropolarimetry as a tool to diagnose magnetic fields at the coronal base. He has lectured on "surprizes in solar physics: an MHD perspective" at Arcetri Observatory. He organized the "Eddy Symposium", a meeting to bring scientists, journalists and politicians together with undergraduate students, to discuss the science behind solar variability and climate.

Professional Website(s): Phil Judge

Publications

(1) Judge, Philip G. 2010: Students, scientists, and family commemorate the life and diverse works of Jack Eddy, Eos, Transactions American Geophysical Union, 92, 7, p. 56-56.

Abstract: In 1976, John Allen Eddy published a seminal article (see Science, 192(4245), 1189-1202) revealing a link between the Little Ice Age, which occurred during the sixteenth through nineteenth centuries, and a period of low sunspot activity, which Eddy called the "Maunder Minimum." This work placed Sun-climate research on a firm scientific footing. Eddy passed away on 10 June 2009. Following Eddy's passions for education and cross-disciplinary research, a symposium was held to expose talented college students to the science and politics of Sun-climate research. Funding from NASA's Living With a Star Targeted Research and Technology program and from the High Altitude Observatory, Advanced Study Program, and Integrated Science Program of the National Center for Atmospheric Research (NCAR) supported keynote speakers and provided scholarships for 30 students (junior year to Ph.D.) from diverse disciplines. Eddy's wife, Barbara, led a session devoted to personal recollections. Spencer Weart (American Institute of Physics) gave an after-dinner tribute using recordings of Eddy from a 1999 interview.

Figure caption: John Allen (Jack) Eddy.

(2) Judge, Philip G., Tritschler, A., Low B.C. 2010: Thermal Fine Structure and Magnetic Fields in the Solar Atmosphere: Spicules and Fibrils, The Astrophysical Journal, 708, 1238.

Abstract: The relationship between observed structures in the solar atmosphere and the magnetic fields threading them is known only for the solar photosphere, even then imprecisely. The authors suggest that some of the fine structures in the more tenuous chromosphere and corona-specifically some populations of spicules and fibrils-correspond to warps in two-dimensional sheet-like structures, as an alternative to conventional interpretations in terms of tube-like structures. The sheets are perhaps related to magnetic tangential discontinuities, which Parker has argued arise naturally in low-beta conditions. Some consequences of this suggestion, if it can be confirmed, are discussed.

Figure caption: A warped sheet rendered in 3D. The brightness is proportional to density integrated along the line of sight. The warps appear as thin, jet-like structures which may correspond to structures seen in the solar chromosphere, previously interpreted as thin straws.

(3) Casini, R., de Wijn, Alfred G., Judge, P. G. 2010: Analysis of Seeing-Induced Polarization Cross-Talk and Modulation Scheme Performance, arXiv preprint.

Abstract: We analyze the generation of polarization cross-talk in Stokes polarimeters by atmospheric seeing, and its effects on the noise statistics of spectropolarimetric measurements for both single-beam and dual-beam instruments. We investigate the time evolution of seeing-induced correlations between different states of one modulation cycle, and compare the response to these correlations of two popular polarization modulation schemes in a dual-beam system. Extension of the formalism to encompass an arbitrary number of modulation cycles enables us to compare our results with earlier work. Even though we discuss examples pertinent to solar physics, the general treatment of the subject and its fundamental results might be useful to a wider community.