A study of the reaction between NaHCO<sub>3</sub> and H: Apparent closure on the chemistry of mesospheric Na

Cox, Rachel M.; Self, Daniel E.; Plane, J. M. C.

doi:10.1029/2000jd900579

Cited by 37 publications

(64 citation statements)

References 14 publications

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“…In contrast, this reaction has a large activation energy (Cox et al, 2001); that is, at higher temperatures it becomes much faster, and the steady-state balance shifts from NaHCO 3 to Na. A secondary effect is that O 3 forms from the recombination of O and O 2 , and this reaction gets slower at higher temperatures: the result is that smaller O 3 concentrations slow down the conversion of Na to NaO, and the larger O concentrations reduce NaO back to Na, enhancing the effect of Reaction (4) becoming faster.…”

Section: Global Latitudinal and Seasonal Variationsmentioning

confidence: 98%

Satellite measurements of the global mesospheric sodium layer

et al. 2007

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Abstract. Optimal estimation theory is used to retrieve the absolute Na density profiles in the mesosphere/lower thermosphere from limb-scanning measurements of the Na radiance at 589 nm in the dayglow. Two years of observations (2003 and 2004), recorded by the OSIRIS spectrometer on the Odin satellite, have been analysed to yield the seasonal and latitudinal variation of the Na layer column abundance, peak height, and peak width. The layer shows little seasonal variation at low latitudes, but the winter/summer ratio increases from a factor of ∼3 at mid-latitudes to ∼10 in the polar regions. Comparison of the measurements made at about 06:00 and 18:00 LT shows little diurnal variation in the layer, apart from the equatorial region where, during the equinoxes, there is a two-fold increase in Na density below 94 km between morning and evening. This is most likely caused by the strong downward wind produced by the diurnal tide between ∼02:00 and 10:00 LT. The dramatic removal of Na below 85 km at latitudes above 50 • during summer is explained by the uptake of sodium species on the ice surfaces of polar mesospheric clouds, which were simultaneously observed by the Odin satellite.

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Section: Global Latitudinal and Seasonal Variationsmentioning

confidence: 98%

Satellite measurements of the global mesospheric sodium layer

et al. 2007

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“…The sodium column abundance reaches a maximum during the period of (JulyAugust), and a minimum around (February-January). Several authors, such Cox et al (2001), Xiong et al (2003), and Drummond et al (2007) noted that the time evolution of the mesospheric sodium column abundance has a characteristic period of one year. It is tempting to suggest that the maximum of the sodium column abundance could be explained by the increase in the meteoric input during this period, which is rich in terms of meteor showers.…”

Section: Column Abundancementioning

confidence: 99%

“…The chemical reactions responsible for the conversion of Na to NaHCO 3 occur rapidly and have small temperature dependencies (Plane 2004(Plane , 1998. NaHCO 3 is converted back to Na by the reaction with H. This reaction has a large activation energy, that is at higher temperatures it becomes much faster, and the steady-state balance shifts from NaHCO 3 to Na (Cox et al 2001). It was suggested that the final sink for sodium on the bottomside of the layer is attachment to aerosol particles (Hunten et al 1980).…”

Section: Mesospheric Sodium Layer Chemistrymentioning

confidence: 99%

Statistics of the sodium layer parameters at low geographic latitude and its impact on adaptive-optics sodium laser guide star characteristics

Moussaoui

Clemesha

Holzlöhner³

et al. 2010

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Aims. To aid the design of laser guide star (LGS) assisted adaptive optics (AO) systems, we present an analysis of the statistics of the mesospheric sodium layer based on long-term observations (35 years). Methods. We analyze measurements of the Na-layer characteristics covering a long period , acquired at latitude 23 • south, in São José dos Compos, São Paulo, Brazil. We note that Paranal (Chile) is located at latitude 24 • south, approximately the same latitude as São Paulo.Results. This study allowed us to assess the availability of LGS-assisted AO systems depending on the sodium layer properties. We also present an analysis of the LGSs spot elongation over the year, as well as the nocturnal and the seasonal variation in the mesospheric sodium layer parameters. Conclusions. The average values of the sodium layer parameters are 92.09 km for the centroid height, 11.37 km for the layer thickness, and 5 × 10 13 m −2 for the column abundance. Assuming a laser of sufficient power to produce an adequate photon return flux for an AO system with a column abundance of 4 × 10 13 m −2 , a telescope could observe at low geographic latitudes with the sodium LGS more than 250 days per year. Increasing this power by 20%, we could observe throughout the entire year.

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“…Note that according to these quantum calculations the dimer should be a sink for sodium, because it will not photolyse at wavelengths above 180 nm, nor react with atomic H (in constrast to NaHCO 3 , Cox et al, 2001;Self and Plane, 2002). In NAMOD, the concentrations of the three major gasphase sodium species, Na, NaHCO 3 and Na + , are determined by full solution of their respective continuity equations.…”

Section: Sodium Chemistrymentioning

confidence: 99%

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

2004

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Abstract.A time-resolved model of the Na layer in the mesosphere/lower thermosphere region is described, where the continuity equations for the major sodium species Na, Na + and NaHCO 3 are solved explicity, and the other shortlived species are treated in steady-state. It is shown that the diurnal variation of the Na layer can only be modelled satisfactorily if sodium species are permanently removed below about 85 km, both through the dimerization of NaHCO 3 and the uptake of sodium species on meteoric smoke particles that are assumed to have formed from the recondensation of vaporized meteoroids. When the sensitivity of the Na layer to the meteoroid input function is considered, an inconsistent picture emerges. The ratio of the column abundance of Na + to Na is shown to increase strongly with the average meteoroid velocity, because the Na is injected at higher altitudes. Comparison with a limited set of Na + measurements indicates that the average meteoroid velocity is probably less than about 25 km s −1 , in agreement with velocity estimates from conventional meteor radars, and considerably slower than recent observations made by wide aperture incoherent scatter radars. The Na column abundance is shown to be very sensitive to the meteoroid mass input rate, and to the rate of vertical transport by eddy diffusion. Although the magnitude of the eddy diffusion coefficient in the 80-90 km region is uncertain, there is a consensus between recent models using parameterisations of gravity wave momentum deposition that the average value is less than 3×10 5 cm 2 s −1 . This requires that the global meteoric mass input rate is less than about 20 t d −1 , which is closest to estimates from incoherent scatter radar observations. Finally, the diurnal variation in the meteoroid input rate only slight perturbs the Na layer, because the residence time of Na in the layer is several days, and diurnal effects are effectively averaged out.

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A study of the reaction between NaHCO₃ and H: Apparent closure on the chemistry of mesospheric Na

Abstract: Abstract. The reaction between sodium bicarbonate (NaHCO3) and atomic H is the only likely route (apart possibly from daytime photolysis) for recycling this major sodium reservoir back to atomic Na in the upper mesosphere.

Cited by 37 publications

References 14 publications

Satellite measurements of the global mesospheric sodium layer

Satellite measurements of the global mesospheric sodium layer

Statistics of the sodium layer parameters at low geographic latitude and its impact on adaptive-optics sodium laser guide star characteristics

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

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A study of the reaction between NaHCO3 and H: Apparent closure on the chemistry of mesospheric Na

Abstract: Abstract. The reaction between sodium bicarbonate (NaHCO3) and atomic H is the only likely route (apart possibly from daytime photolysis) for recycling this major sodium reservoir back to atomic Na in the upper mesosphere.

Cited by 37 publications

References 14 publications

Satellite measurements of the global mesospheric sodium layer

Satellite measurements of the global mesospheric sodium layer

Statistics of the sodium layer parameters at low geographic latitude and its impact on adaptive-optics sodium laser guide star characteristics

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

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A study of the reaction between NaHCO₃ and H: Apparent closure on the chemistry of mesospheric Na