TY - JOUR
T1 - Time resolved N2 triplet state vibrational populations and emissions associated with red sprites
AU - Morrill, J. S.
AU - Bucsela, E. J.
AU - Pasko, V. P.
AU - Berg, S. L.
AU - Heavner, M. J.
AU - Moudry, D. R.
AU - Benesch, W. M.
AU - Wescott, E. M.
AU - Sentman, D. D.
N1 - Funding Information:
The computer time was supported by the Solar Physics Branch and X-Ray Astronomy Branch in the Space Science Division of the Naval Research Laboratory and STAR Laboratory of Stanford University. The atmospheric transmission calculations were performed using the MOSART model as implemented in the SSGM (Synthetic Scene Generation Model) at the Space Science Division of the Naval Research Laboratory. E. J. Bucsela was supported by an ASEE Postdoctoral Fellowship. J. S. Morrill was supported in part by the Edison Memorial graduate training program at the Naval Research Laboratory; V. P. Pasko was supported by an NSF Postdoctoral Fellowship under NSF grant ATM-9522816 to Stanford University; and D. R. Moudry, M. J. Heavner, D. D. Sentman, and E. M. Wescott were supported by NASA grant NAG5-5019. The authors would like to thank B. D. Green for providing the B 3 Π g vibrational distributions, G. R. Swenson for numerous interesting conversations on red sprites, and U. S. Inan, T. F. Bell, and S. G. Queen for their critical review of the manuscript. Zubek and King 1994 Van Zyl et al. 1995, Vallance Jones and Gattinger 1974, Roussel-Dupre and Gurevich 1996, Richard et al. 1994, Piper 1993, Lehtinen et al. 1997, 1996, Inan et al. 1996, Fukunishi et al. 1996b, Fishman et al. 1994 Carragher et al. 1991b
PY - 1998/5/1
Y1 - 1998/5/1
N2 - The results of a quasi-electrostatic electron heating model were combined with a time dependent N2 vibrational level population model to simulate the spectral distributions and absolute intensities observed in red sprites. The results include both N2 excited state vibrational level populations and time profiles of excited electronic state emission. Due to the long atmospheric paths associated with red sprite observations, atmospheric attenuation has a strong impact on the observed spectrum. We present model results showing the effect of atmospheric attenuation as a function of wavelength for various conditions relevant to sprite observations. In addition, our model results estimate the variation in the relative intensities of a number of specific N2 emissions in sprites (1PG, 2PG, and VK) in response to changes in observational geometry. A recent sprite spectrum, measured from the Wyoming Infrared Observatory (WIRO) on Jelm Mountain, during July, 1996, has been analyzed and includes N2 1PG bands down to v' = 1. In addition to N2 1PG, our analysis of this spectrum indicates the presence of spectral features which are attributable to N+2 Meinel emission. However, due to the low intensity in the observed spectrum and experimental uncertainties, the presence of the N+2 (A2Π(u)) should be considered preliminary. The importance of both the populations of the lower levels of the N2(B3Π(g)) and the N2(B3Π(g))/ N+2(A2Π(g)) population ratio in the diagnosis of the electron energies present in red sprites is discussed. While the current spectral analysis yields a vibrational distribution of the N2(B3Π(g)) which requires an average electron energy of only 1-2 eV, model results do indicate that the populations of the lower levels of the N2(B3Π(g)) will increase with increases in the electron energy primarily due to cascade. Considering the importance of the populations of the lower vibrational levels, we are beginning to analyze additional sprite spectra, measured at higher resolution, which contain further information on the population of B(v = 1).
AB - The results of a quasi-electrostatic electron heating model were combined with a time dependent N2 vibrational level population model to simulate the spectral distributions and absolute intensities observed in red sprites. The results include both N2 excited state vibrational level populations and time profiles of excited electronic state emission. Due to the long atmospheric paths associated with red sprite observations, atmospheric attenuation has a strong impact on the observed spectrum. We present model results showing the effect of atmospheric attenuation as a function of wavelength for various conditions relevant to sprite observations. In addition, our model results estimate the variation in the relative intensities of a number of specific N2 emissions in sprites (1PG, 2PG, and VK) in response to changes in observational geometry. A recent sprite spectrum, measured from the Wyoming Infrared Observatory (WIRO) on Jelm Mountain, during July, 1996, has been analyzed and includes N2 1PG bands down to v' = 1. In addition to N2 1PG, our analysis of this spectrum indicates the presence of spectral features which are attributable to N+2 Meinel emission. However, due to the low intensity in the observed spectrum and experimental uncertainties, the presence of the N+2 (A2Π(u)) should be considered preliminary. The importance of both the populations of the lower levels of the N2(B3Π(g)) and the N2(B3Π(g))/ N+2(A2Π(g)) population ratio in the diagnosis of the electron energies present in red sprites is discussed. While the current spectral analysis yields a vibrational distribution of the N2(B3Π(g)) which requires an average electron energy of only 1-2 eV, model results do indicate that the populations of the lower levels of the N2(B3Π(g)) will increase with increases in the electron energy primarily due to cascade. Considering the importance of the populations of the lower vibrational levels, we are beginning to analyze additional sprite spectra, measured at higher resolution, which contain further information on the population of B(v = 1).
UR - http://www.scopus.com/inward/record.url?scp=0032466701&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032466701&partnerID=8YFLogxK
U2 - 10.1016/S1364-6826(98)00031-5
DO - 10.1016/S1364-6826(98)00031-5
M3 - Article
AN - SCOPUS:0032466701
SN - 1364-6826
VL - 60
SP - 811
EP - 829
JO - Journal of Atmospheric and Solar-Terrestrial Physics
JF - Journal of Atmospheric and Solar-Terrestrial Physics
IS - 7-9
ER -