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An important research focus for me is the study of the electrodynamics of the equatorial ionosphere through measurements of the neutral winds above 200 km with a FPI interferometer.   The first observatory from which I made these measurements (through collaboration with my colleague Fred Biondi, which started in 1983) is located to the northeast of the city of Arequipa, Peru, on the grounds of the NASA lidar tracking station. The data from this facility can be combined with 50 MHz radar observations of the F-region plasma drifts that are made by the Jicamarca incoherent scatter radar facility located to the north to form an unique data base of neutral winds and plasma drift measurements aimed at helping us to understand the electrodynamics of the equatorial ionosphere. This activity is designated as part of the research theme "Space Weather" in which we seek to improve our capability to predict the behavior of the ionospheric plasma, especially for the equatorial region.  Photos of the Arequipa Observatory are located here.

This effort has been expanded by the installation of another Fabry-Perot observatory that has been installed at the location of a mountain ridge overlooking the Jicamarca Radio Observatory. This effort was achieved thanks to the great efforts of Mr. Oscar Veliz, Dr. Jorge Chau, and other JRO colleagues who did the heavy lifting to carry the bricks, mortar, air conditioning, and the optical components one by one up the trail to the observatory building (see the MRH web site for photos). This observatory was commissioned on 15 August, 2009, after a dedication ceremony led by Dr. Jorge Chau, and attended by Oscar Veliz, and students from Clemson University (Brooke Baker, Greg Twork), and Russell Hedden from Cornell University.  This observatory will be used to obtain common volume measurements of the neutral wind vector with simultaneous measurements obtained by the Arequipa FPI instrument. This observatory would look to the northwest and the MRH observatory would look to the southeast so that overlapping lines of sight measurements of Doppler shifts and Doppler broadening are obtained in the same volume of the thermosphere region.  The best justification, though, for the MRH observatory is that simultaneous measurements of the thermospheric wind vector and the plasma ion drifts would be possible with the union of the FPI with the Jicamarca ISR radar making measurements at the same location. It should be possible, at last, to determine whether the F-region dynamo is fully activated or not following the evening twilight hours. This is a point first raised by Dr. Ron Woodman, Instituto Geofisico del Peru, nearly 50 years ago at the early beginnings of the JRO radar facility. Photos of the MRH Observatory are located here.

Another important aspect of the FPI research at the Arequipa site is the application of this instrument to the study of the population of the topside thermosphere region by hot oxygen atoms that are produced by the molecular dissociation of molecular oxygen ions formed by the charge transfer reaction of oxygen ions with molecular oxygen. The old Arequipa FPI interferometer has been upgraded with the replacement of the PMT detector previously used, the GaAs photomultiplier, with a very sensitive CCD high quality digital camera made by Andor Technology.  The present sensitivity of this instrument was increased by 15 times. This upgrade (carried out in collaboration with Prof. M.A. Biondi, Univ. of Pittsburgh and Dr. Peter Sherwood, Interactive Technology, Inc.) has opened new avenues of research. 

Related to these issues of equatorial aeronomy is the study of daytime equatorial aeronomy for the upper atmosphere at altitudes of 150 miles high (250 km). This is a new research path I am particularly excited to share with students and colleagues. Funding provided by the Air Force Office of Scientific Research and the National Science Foundation provided Clemson University the means to purchase a triple etalon FPI observatory housed in a trailer customized to provide a stabilized thermal environment. The three etalons combined reduces the instrument bandwidth to the daysky continuum background and minimizes the extent to which the sky continuum affects the measurements that determine the Doppler line of sight shift that is introduced by atmospheric winds.

This instrument was designed and constructed by the Michigan Aerospace Corporation located in Ann Arbor, Michigan.  It has been deployed to Huancayo, Peru, after test operations at an eastern New York as a part of joint operations with the Millstone Hill Observatory (Weston, MA) optical and radar instrumentation. This effort will make possible the improved understanding of the dynamics of the upper atmosphere that is connected to the properties and behavior of radio wave propagation through the ionosphere region. The instrument will automatically transform into a single etalon instrument for nighttime measurements of winds and temperatures with very high sensitivity.  Probably the best feature of this instrument will be its robust stability of ~ 1 m/s drift over ten hours.  These collaborative observations with Millstone Hill Observatory were completed in the fall of 2005, and this trailer has been transported by Dr. Andrew Gerrard (New Jersey Institute of Technology) to Peru for daytime and nighttime studies of the equatorial dynamics as part of the network already established by the Arequipa and MRH FPI observatories.  Details regarding the first set of daytime measurements are given here.

Subpages (2): Arequipa MRH