Data‐model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

Abstract

[1] Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer a Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman b, Lyman g and He 584 Å emission intensities. In this paper, coincident EURD Lyman b and PBO Balmer a radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A datamodel comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman b irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

Geocoronal hydrogen studies using Fabry–Perot interferometers, part 1: Instrumentation, observations, and analysis

“…Complementing these ground-based measurements, satellite missions, e.g., EURD (Garcı´a Primo, 2001), FUSE (Feldman et al, 2001), IMAGE/GEO (Østgaard et al, 2003), are providing large data sets of FUV and EUV emission measurements including geocoronal Lyman line intensities. With the data sets now available (see e.g., Bishop et al, 2004), updated solar Lyman line center flux observations (e.g., Warren et al, 1998), the use of astronomical standards for absolute radiance calibrations (see e.g., Scherb, 1981), and refined radiative transport modeling for site specific observations (Bishop, 1999), the goal of developing the Balmer a emission as a diagnostic of the upper atmosphere (e.g., as a tracer of atmospheric chemistry, variability, and exospheric characteristics) appears to be within reach.…”

“…Mid-latitude geocoronal hydrogen Balmer a observations by Wisconsin observers now span 1977 to the present with some gaps in the data record (Reynolds et al, 1973;Yelle and Roesler, 1985;Shih et al, 1985;Nossal et al, 1993Nossal et al, , 1997Nossal et al, , 1998Nossal et al, , 2001Nossal et al, , 2004Bishop et al, 2001Bishop et al, , 2004Mierkiewicz, 2002). The majority of these observations were made from Wisconsin, with additional observations from Haleakala (HI) (Harlander and Roesler, 1989;Bishop et al, 2001), and Kitt Peak (AZ) (Nossal et al, , 2004.…”

“…Recently, Bishop et al (2004) used same-night ground-based Balmer a data from PBO and geocoronal Lyman b measurements from the Espectro´grafo Ultravioleta extremo para la Radiacio´n Difusa (EURD) instrument on the Spanish satellite MINISAT-1 (provided by J.F. Go´mez and C. Morales of the Laboratorio de Astrofisica Espacial y Fı´sica Fundamental, INTA, Madrid, Spain) in order to investigate the modeling constraints imposed by two sets of independent geocoronal measurements, both of which rely on astronomical calibration methods.…”

“…Although ground-based Fabry-Perot observations of geocoronal hydrogen have been made over the last several decades with increasing instrumental capabilities (Reynolds et al, 1973;Atreya et al, 1975;Meriwether et al, 1980;Yelle and Roesler, 1985;Shih et al, 1985, Kerr et al, 1986, 2001aKerr and Tepley, 1988;He et al, 1993; , 1997Bishop et al, 2001Bishop et al, , 2004Mierkiewicz, 2002; and references therein), recent advances in detector technology, such as the charged-coupled-device (CCD), and its application to Fabry-Perot spectroscopy (e.g., CCD annular summing spectroscopy), have greatly improved the quality and quantity of geocoronal Balmer a emissions data. Scientific areas of focus include:…”

“…This paper will discuss the technique of FabryPerot spectroscopy as applied to ground-based geocoronal hydrogen Balmer a observations, including strategies for obtaining data of sufficient precision and scope to address the scientific areas of focus outlined above. Observations by the Wisconsin group and collaborators (Reynolds et al, 1973;Yelle and Roesler, 1985;Shih et al, 1985;Harlander and Roesler, 1989;Nossal et al, 1993Nossal et al, , 1997Nossal et al, , 1998Nossal et al, , 2001Nossal et al, , 2004Coakley et al, 1996;Bishop et al, 2001Bishop et al, , 2004Mierkiewicz, 2002) will be used to illustrate capabilities and challenges associated with using Fabry-Perot spectroscopy as a means to explore the hydrogen geocorona.…”