Atmospheric composition in the lower thermosphere

Colegrove, F. D.; Johnson, Francis S.; Hanson, W. B.

doi:10.1029/jz071i009p02227

Cited by 183 publications

(103 citation statements)

References 14 publications

(3 reference statements)

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“…We use a simplified formulation of thermal diffusion that is analogous to its appearance in the binary diffusion equations, after Colegrove et al [5]. In this treatment, a constant value of α He = −0.38 is used.…”

Section: Implementing Helium As a Major Speciesmentioning

confidence: 99%

“…(34) and (39) in the appendix, the strength of this coupling depends on the mutual diffusion coefficients. Dickinson et al [9] assumed these coefficients to take the form D = D 0 (T /T 00 ) 1.75 (p 00 /p) for the major species, after Colegrove et al [5]. Accordingly, the elements of α have been normalized by this functional form.…”

Section: Implementing Helium As a Major Speciesmentioning

confidence: 99%

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Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

Sutton¹

2015

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)27-10-2015 (From -To) REPORT TYPE Final Report DATES COVERED AFRL-RV-PS-TR-2015-0168 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)AFRL/RVBXI SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. (OPS-15-9186 dtd 17 Nov 2015) SUPPLEMENTARY NOTES ABSTRACTDuring this task, we established a method for extracting the most significant basis functions from a physics-based model of the thermosphere and ionosphere. A new model was then constructed by replacing the spherical harmonic functions used in an existing semiempirical thermosphere model with these basis functions. The resulting hybrid model, published in the Space Weather Journal, demonstrated the ability to represent sparse thermospheric data in a more accurate and efficient way. In addition, we chose Jacchia 1970 as our underlying semi-empirical model so that the new hybrid model functions as a direct replacement for the High Accuracy Satellite Drag Model used by AFSPC and the JSpOC. We also worked to improve the hybrid model by investigating the limitations of and possible improvements to the underlying assumptions imposed by the chosen models. In particular, we realized that there was a large and potentially significant component missing from all general circulation models, that being the appropriate treatment of helium in the upper thermosphere. To rectify this situation, we undertook the project of adding helium to the solution of a first-principles community model of the thermosphere and ionosphere. In doing this, we discovered that this could only be done self-consistently by solving for helium as a major species, as opposed to as a minor species. The product of this work was the first physics-based model to accurately simulate the seasonal and latitudinal behavior of the helium distribution. This work was published in the Journal of Geophysical Research. 64This page is intentionally left blank.Approved for public release; distribution is unlimited.

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Section: Implementing Helium As a Major Speciesmentioning

confidence: 99%

Section: Implementing Helium As a Major Speciesmentioning

confidence: 99%

Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

Sutton¹

2015

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“…The mutual diusion coecients for h x 2 Ày and h x 2 Ày 2 are given by Colegrove et al (1966) and h x 2 Àx 2 by Pavlov (private communication). Equations (3) and (4) are then solved using an implicit ®nite dierence scheme for the ®rst ®ve vibrationally excited states of molecular nitrogen.…”

Section: The Inclusion Of Vibrationally Excited Nitrogenmentioning

confidence: 99%

The effect of vibrationally excited nitrogen on the low-latitude ionosphere

et al. 1997

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Abstract. The ®rst ®ve vibrationally excited states of molecular nitrogen have been included in the Sheeld University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O ions are converted to NO + ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the eect of including vibrationally excited molecular nitrogen on the lowlatitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest eect being at the location of the equatorial trough.

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“…HAYS and OLIVERO (1970) derived the model assuming O and OH density profiles proposed by HESSTVEDT (1967), however HESSTVEDT had estimated the densities of O and OH using different value of the eddy diffusion coefficient from HAYS and OLIVERO's. Many investigators pointed out that O density was strongly affected by eddy diffusion processes in the lower thermosphere (COLEGROVE et al, 1966;SHIMAZAKI, 1967;HESSTVEDT, 1967;SHIMAZAKI andLAIRD, 1970, 1972;BOWMAN et al, 1970;KENESEA and ZIMMERMAN, 1970;GEORGE et al, 1972;. Therefore it seems necessary to calculate simultaneously the densities of CO2, O, OH and other constituents using same value of eddy diffusion coefficient.…”

Section: Introductionmentioning

confidence: 99%

“…Instead, using the chemical-eddy diffusion model proposed by COLEGROVE et al (1966) we calculate the distributions of constituents with Some part of this paper is printed in also Tenki, 20, 435-441, 1973 in Japanese. long life time which are affected considerably by eddy diffusional transport. In addition to these facts, we consider the effect of solar emission lines such as H ly-a which are not previously taking into account.…”

Section: Introductionmentioning

confidence: 99%

Carbon dioxide density and 15.MU. band radiation in the mesosphere and lower thermosphere.

Iwasaka

Horii

1974

J. geomagn. geoelec

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The CO2 density profile is decided using the photochmical-eddy diffusion model, and the cooling rate of CO2 15 p band in the lower thermoshere is discussed. These results show that the cooling rate of 15 p band decreases somewhat in comparison with the estimation using the assumption of constant mixing ratio of CO2. The O2(1Qg) density profile which is simultaneously calculated has small second peak near 85km.

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Atmospheric composition in the lower thermosphere

Cited by 183 publications

References 14 publications

Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

The effect of vibrationally excited nitrogen on the low-latitude ionosphere

Carbon dioxide density and 15.MU. band radiation in the mesosphere and lower thermosphere.

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