Abstract
Abstract. In December 2010 the last campaign of the German-Norwegian sounding rocket project ECOMA (Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere) was conducted from Andøya Rocket Range in northern Norway (69° N, 16° E) in connection with the Geminid meteor shower. The main instrument on board the rocket payloads was the ECOMA detector for studying meteoric smoke particles (MSPs) by active photoionization and subsequent detection of the produced charges (particles and photoelectrons). In addition to photoionizing MSPs, the energy of the emitted photons from the ECOMA flash-lamp is high enough to also photoionize nitric oxide (NO). Thus, around the peak of the NO layer, at and above the main MSP layer, photoelectrons produced by the photoionization of NO are expected to contribute to, or even dominate above the main MSP-layer, the total measured photoelectron current. Among the other instruments on board was a set of two photometers to study the O2 (b1Σg+−X3Σg
Highlights
1.1 Nitric oxide in the middle atmosphereThe presence of nitric oxide (NO) in the upper atmosphere was first suggested by Kaplan (1939) and later confirmed by Barth (1964)
Considering the uncertainties in the rate coefficients and excitation parameters in the nightglow O retrieval, the possible temperature dependence of the two-body reaction path (Reaction R2, Eq 2), and the variability of the neutral atmosphere density and temperature, the peak NO number density inferred from the photometric measurements on ECOMA7 is between 3.7×108 cm−3 and 6.0×108 cm−3
The NO number densities inferred from the simultaneous photoelectron measurement by the ECOMA detector above the main meteoric smoke particles (MSPs) layer do not, agree with the densities inferred from the photometric measurements
Summary
The presence of nitric oxide (NO) in the upper atmosphere was first suggested by Kaplan (1939) and later confirmed by Barth (1964). N(2D,4S) is produced in the reaction of N+2 with O, through impact dissociation of N2 by energetic electrons (auroral secondary electrons and fast photoelectrons due to solar soft X-rays) and through dissociative recombination of NO+ or N+2 with ambient electrons This results in a production of NO at high latitudes that is mostly under geomagnetic control and highly variable in space and time. This results in a broad emission feature in the Earth’s visible and near infrared nightglow spectrum, the NO2 nightglow continuum This emission can be used, together with knowledge about the local O concentration and in the absence of auroral emissions, to infer NO number densities in the upper mesosphere and lower thermosphere region (Sharp, 1978; Witt et al, 1981; McDade et al, 1986a; von Savigny et al, 1999; Gattinger et al, 2010; Enell et al, 2011; Sheese et al, 2011).
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