[1] Atomic oxygen (O) is a fundamental component in chemical aeronomy of Earth's mesosphere and lower thermosphere region extending from approximately 50 km to over 100 km in altitude. Atomic oxygen is notoriously difficult to measure, especially with remote sensing techniques from orbiting satellite sensors. It is typically inferred from measurements of the ozone concentration in the day or from measurements of the Meinel band emission of the hydroxyl radical (OH) at night. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite measures OH emission and ozone for the purpose of determining the O-atom concentration. In this paper, we present the algorithms used in the derivation of day and night atomic oxygen from these measurements. We find excellent consistency between the day and night O-atom concentrations from daily to annual time scales. We also examine in detail the collisional relaxation of the highly vibrationally excited OH molecule at night measured by SABER. Large rate coefficients for collisional removal of vibrationally excited OH molecules by atomic oxygen are consistent with the SABER observations if the deactivation of OH(9) proceeds solely by collisional quenching. An uncertainty analysis of the derived atomic oxygen is also given. Uncertainty in the rate coefficient for recombination of O and molecular oxygen is shown to be the largest source of uncertainty in the derivation of atomic oxygen day or night. , et al. (2013), Atomic oxygen in the mesosphere and lower thermosphere derived from SABER: Algorithm theoretical basis and measurement uncertainty,
[1] We present observations of the infrared radiative cooling by carbon dioxide (CO 2 ) and nitric oxide (NO) in Earth's thermosphere. These data have been taken over a period of 7 years by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite and are the dominant radiative cooling mechanisms for the thermosphere. From the SABER observations we derive vertical profiles of radiative cooling rates (W m −3 ), radiative fluxes (W m −2 ), and radiated power (W). In the period from January 2002 through January 2009, we observe a large decrease in the cooling rates, fluxes, and power consistent with the declining phase of solar cycle 23. The power radiated by NO during 2008 when the Sun exhibited few sunspots was nearly one order of magnitude smaller than the peak power observed shortly after the mission began. Substantial short-term variability in the infrared emissions is also observed throughout the entire mission duration. Radiative cooling rates and radiative fluxes from NO exhibit fundamentally different latitude dependence than do those from CO 2 , with the NO fluxes and cooling rates being largest at high latitudes and polar regions. The cooling rates are shown to be derived relatively independent of the collisional and radiative processes that drive the departure from local thermodynamic equilibrium (LTE) in the CO 2 15 mm and the NO 5.3 mm vibration-rotation bands. The observed NO and CO 2 cooling rates have been compiled into a separate data set and represent a climate data record that is available for use in assessments of radiative cooling in upper atmosphere general circulation models.Citation: Mlynczak, M. G., et al. (2010), Observations of infrared radiative cooling in the thermosphere on daily to multiyear timescales from the TIMED/SABER instrument,
Updated night atomic oxygen concentration (O) profiles from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the National Aeronautics and Space Administration TIMED satellite are presented. These are derived from measurements of the OH(υ = 9 + 8) volume emission rates and photochemical balance relationships. The new night O concentrations are smaller than those originally derived in 2013 and yield physically realistic global annual mean energy budgets in the upper mesosphere and lower thermosphere. The update to the night O atom profiles is motivated by recent discovery and verification of large rates of collisional quenching of OH(υ) by atomic oxygen. The kinetic model relating the SABER‐observed OH emission rates to atomic oxygen is now consistent with these larger quenching rates and other literature values. The new, smaller SABER night O also confirms that SABER daytime ozone is too large. The new night O and OH(υ) model impacts the inference of day and night atomic hydrogen.
[1] During geomagnetic storms Joule heating dissipation is the dominant form of magnetospheric energy input that is responsible for many chemical and dynamical variations in the thermosphere. One such thermospheric variation is the dramatic increase of thermospheric temperature and nitric oxide (NO) density and thus radiative emission by NO. This paper gives for the first time a quantitative assessment of the relationship between global Joule heating power and global NO radiative cooling power. It is found that, when averaged over a time interval of 24 h along with a time lag of 10 h, global Joule heating power is closely correlated with global NO cooling power. On average, the increased energy release through NO 5.3 mm infrared emission accounts for about 80% of Joule heating energy input under disturbed conditions. The paper also presents a first attempt to parameterize global NO power using the Kp and F 10.7 indices. Under nonstorm conditions the best correlation is found when the daily global NO power lags behind the solar flux input by 1 day. The predicted NO power based on this parameterization scheme reproduces many features in the observed global NO power by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument over the 7 year period from 2002 to 2008. The predicted global NO power correlates well with the SABER measurements, with a correlation coefficient of 0.89.
We present a multiyear superposed epoch study of the Sounding of the Atmosphere using Broadband Emission Radiometry nitric oxide (NO) emission data. NO is a trace constituent in the thermosphere that acts as cooling agent via infrared (IR) emissions. The NO cooling competes with storm time thermospheric heating, resulting in a thermostat effect. Our study of nearly 200 events reveals that shock‐led interplanetary coronal mass ejections (ICMEs) are prone to early and excessive thermospheric NO production and IR emissions. Excess NO emissions can arrest thermospheric expansion by cooling the thermosphere during intense storms. The strongest events curtail the interval of neutral density increase and produce a phenomenon known as thermospheric “overcooling.” We use Defense Meteorological Satellite Program particle precipitation data to show that interplanetary shocks and their ICME drivers can more than double the fluxes of precipitating particles that are known to trigger the production of thermospheric NO. Coincident increases in Joule heating likely amplify the effect. In turn, NO emissions are more than double. We discuss the roles and features of shock/sheath structures that allow the thermosphere to temper the effects of extreme storm time energy input and explore the implication these structures may have on mesospheric NO. Shock‐driven thermospheric NO IR cooling likely plays an important role in satellite drag forecasting challenges during extreme events.
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