scholarly journals Inferring thermospheric composition from ionogram profiles: A calibration with the TIMED spacecraft

2019 ◽  
Author(s):  
Christopher J. Scott ◽  
Shannon Jones ◽  
Luke A. Barnard
Keyword(s):  
Dissociative Recombination ◽  
Temporal Variations ◽  
Molecular Ions ◽  
Upper Atmosphere ◽  
Global Network ◽  
G Factor ◽  
Satellite Drag ◽  
Important Region ◽  
Ion Production ◽  
Sensitive Function

Abstract. Measurements of thermospheric composition via ground-based instrumentation are challenging to make and so details about this important region of the upper atmosphere are currently sparse. We present a technique that deduces quantitative estimates of thermospheric composition from ionospheric data, for which there is a global network of stations. The visibility of the F1 peak in ionospheric soundings from ground-based instrumentation is a sensitive function of thermospheric composition. The ionospheric profile in the transition region between F1 and F2 peaks can be expressed by the G factor, a function of ion production rate and loss rates via ion-atom interchange reactions and dissociative recombination of molecular ions. This in turn can be expressed as the square of the ratio of ions lost via these processes. We compare estimates of the G factor obtained from ionograms recorded at Kwajalein (9° N, 167.2° E) for 25 times during which the TIMED spacecraft recorded approximately co-located measurements of the neutral thermosphere. We find a linear relationship between √G and the molecular: atomic composition ratio, with a gradient of 2.23 ± 0.17 and an offset of 1.66 ± 0.19. This relationship reveals the potential for using ground-based ionospheric measurements to infer quantitative variations in the composition of the neutral thermosphere. Such information can be used to investigate spatial and temporal variations in thermospheric composition which in turn has applications such as understanding the response of thermospheric composition to climate change and the efficacy of the upper atmosphere on satellite drag.

scholarly journals Inferring thermospheric composition from ionogram profiles: a calibration with the TIMED spacecraft

2021 ◽  
Vol 39 (2) ◽  
pp. 309-319
Author(s):  
Christopher J. Scott ◽  
Shannon Jones ◽  
Luke A. Barnard
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions ◽  
Upper Atmosphere ◽  
Global Network ◽  
G Factor ◽  
Important Region ◽  
Term Change ◽  
Ion Production ◽  
Sensitive Function

Abstract. We present a method for augmenting spacecraft measurements of thermospheric composition with quantitative estimates of daytime thermospheric composition below 200 km, inferred from ionospheric data, for which there is a global network of ground-based stations. Measurements of thermospheric composition via ground-based instrumentation are challenging to make, and so details about this important region of the upper atmosphere are currently sparse. The visibility of the F1 peak in ionospheric soundings from ground-based instrumentation is a sensitive function of thermospheric composition. The ionospheric profile in the transition region between F1 and F2 peaks can be expressed by the “G” factor, a function of ion production rate and loss rates via ion–atom interchange reactions and dissociative recombination of molecular ions. This in turn can be expressed as the square of the ratio of ions lost via these processes. We compare estimates of the G factor obtained from ionograms recorded at Kwajalein (9∘ N, 167.2∘ E) for 25 times during which the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) spacecraft recorded approximately co-located measurements of the neutral thermosphere. We find a linear relationship between G and the molecular-to-atomic composition ratio, with a gradient of 2.55±0.40. Alternatively, using hmF1 values obtained by ionogram inversion, this gradient was found to be 4.75±0.4. Further, accounting for equal ionisation in molecular and atomic species yielded a gradient of 4.20±0.8. This relationship has potential for using ground-based ionospheric measurements to infer quantitative variations in the composition of the neutral thermosphere via a relatively simple model. This has applications in understanding long-term change and the efficacy of the upper atmosphere on satellite drag.

Dissociative recombination of electrons and molecular ions

1982 ◽  
Vol 136 (1) ◽  
pp. 25 ◽  
Author(s):  
Aleksandr V. Eletskii ◽  
Boris M. Smirnov
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions

scholarly journals Space Weather, SuperDARN and the Tasmanian Tiger

1997 ◽  
Vol 50 (4) ◽  
pp. 773 ◽  
Author(s):  
Raymond A. Greenwald
Keyword(s):  
Solar Wind ◽  
Electric Fields ◽  
Space Weather ◽  
Interplanetary Space ◽  
Rapid Evolution ◽  
Upper Atmosphere ◽  
Global Network ◽  
Pressure Gradients ◽  
Earth’S Magnetosphere ◽  
Earth's Magnetosphere

The plasma environment extending from the solar surface through interplanetary space to the outermost reaches of the Earth’s atmosphere and magnetic field is dynamic, often disturbed, and capable of harming humans and damaging manmade systems. Disturbances in this environment have been identified as space weather disturbances. At the present time there is growing interest in monitoring and predicting space weather disturbances. In this paper we present some of the difficulties involved in achieving this goal by comparing the processes that drive tropospheric-weather systems with those that drive space-weather systems in the upper atmosphere and ionosphere. The former are driven by pressure gradients which result from processes that heat and cool the atmosphere. The latter are driven by electric fields that result from interactions between the streams of ionised gases emerging from the Sun (solar wind) and the Earth’s magnetosphere. Although the dimensions of the Earth’s magnetosphere are vastly greater than those of tropospheric weather systems, the global space-weather response to changes in the solar wind is much more rapid than the response of tropospheric-weather systems to changing conditions. We shall demonstrate the rapid evolution of space-weather systems in the upper atmosphere through measurements with a global network of radars known as SuperDARN. We shall also describe how the SuperDARN network is evolving, including a newly funded Australian component known as the Tasman International Geospace Environmental Radar (TIGER).

scholarly journals Quantum-state–selective electron recombination studies suggest enhanced abundance of primordial HeH+

Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. 676-679 ◽  
Author(s):  
Oldřich Novotný ◽  
Patrick Wilhelm ◽  
Daniel Paul ◽  
Ábel Kálosi ◽  
Sunny Saurabh ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Dissociative Recombination ◽  
Molecular Ions ◽  
Rate Coefficients ◽  
Specific Rate ◽  
Electron Recombination ◽  
Recombination Rates ◽  
Rotational States ◽  
Hydride Ion ◽  
Helium Hydride

The epoch of first star formation in the early Universe was dominated by simple atomic and molecular species consisting mainly of two elements: hydrogen and helium. Gaining insight into this constitutive era requires a thorough understanding of molecular reactivity under primordial conditions. We used a cryogenic ion storage ring combined with a merged electron beam to measure state-specific rate coefficients of dissociative recombination, a process by which electrons destroy molecular ions. We found a pronounced decrease of the electron recombination rates for the lowest rotational states of the helium hydride ion (HeH+), compared with previous measurements at room temperature. The reduced destruction of cold HeH+ translates into an enhanced abundance of this primordial molecule at redshifts of first star and galaxy formation.

The dissociative recombination of cold polyatomic molecular ions measured at a storage ring

1997 ◽  
Author(s):  
O. Heber ◽  
L. H. Andersen ◽  
D. Kella ◽  
H. B. Pedersen ◽  
L. Vejby-Christensen ◽  
...  
Keyword(s):  
Storage Ring ◽  
Dissociative Recombination ◽  
Molecular Ions

scholarly journals Dissociative recombination of stored and phase-spaced cooled molecular ions in cryring

1993 ◽  
Author(s):  
M. Larsson ◽  
G. Sundström ◽  
M. Carlson ◽  
H. Danared ◽  
A. Källberg ◽  
...  
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions
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