Sounding Of The Atmosphere Using Broadband Emission Radiometry Instrument Research Articles

Observational Evidence for the Influence of Diurnal Tide in Driving Winds in the Polar Upper Mesosphere and Lower Thermosphere

AbstractThe meteor radar wind observations over Esrange (67.9°N, 21.10°E) and Rothera (67.5°S, 68.1°W), located respectively in the northern and southern polar latitudes show seasonal variation in the upper mesosphere and lower thermosphere (UMLT) winds with strong westward flow in the zonal wind and equatorward flow in the meridional wind during April‐September over Esrange and October‐February over Rothera. The semi‐diurnal tide shows larger amplitudes over Esrange than over Rothera. However, the diurnal tide (DT) shows comparable amplitudes in both stations. The DT amplitude decreases with height over both stations. Significant correlations between the DT amplitude and mean zonal wind (−0.74 for Esrange and −0.54 and −0.77 for Rothera) indicate the possible role of DT in driving the westward winds. The space‐time spectral analysis of the temperature obtained from the radiance observations of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on board the TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite reveals the summer maximum of migrating diurnal tide of zonal wavenumber 1 (DW1) over both 60°N and 60°S, indicating that the DT is mostly composed of DW1. These results suggest that the westward winds in the polar UMLT region are largely driven by the westward momentum contributed by the DW1 tide due to its interaction with the background wind.

Significant Variations of Thermospheric Nitric Oxide Cooling during the Minor Geomagnetic Storm on 6 May 2015

Using observations by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on board the TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) satellite and simulations by the TIEGCM (Thermosphere-Ionosphere-Electrodynamics General Circulation Model), we investigate the daytime variations of thermospheric nitric oxide (NO) cooling during the geomagnetic storm on 6 May 2015. The geomagnetic storm was minor, as the minimum Dst was −28 nT, the maximum Kp was 5+ and the maximum AE was 1259 nT. However, significant enhancements of peak NO cooling rate and prominent decreases in the peak NO cooling altitude were observed from high latitudes to low latitudes in both hemispheres on the dayside by the SABER instrument. The model simulations underestimate the response of peak NO cooling and have no significant variation of the altitude of peak NO cooling rate on the dayside during this minor geomagnetic storm. By investigating the temporal and latitudinal variations of vertical NO cooling profiles inferred from SABER data, we suggest that the horizontal equatorward winds caused by the minor geomagnetic storm were unexpectedly strong and thus play an important role in inducing these significant daytime NO cooling variations.

Retrieving daytime distributions of O, H, OH, HO2, and chemical heating rate in the mesopause region from satellite observations of ozone and OH* volume emission: The evaluation of the importance of the reaction H + O3 → O2 + OH in the ozone balance

Based on data from the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument onboard the TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite observations 2003–2015, we retrieved atomic oxygen and atomic hydrogen distributions in the mesopause region (∼77 km–100 km) for daytime conditions taking into account the reaction of the ozone with atomic hydrogen in the ozone balance equation (OBE). Subsequently we calculated daytime distributions of OH, HO2, and the corresponding total chemical heating rate (CHR) from seven exothermic chemical reactions. The novelty of our approach is that we consider, to the best of our knowledge, the reaction H + O3 → O2 + OH in the daytime OBE for the retrieving procedure for the first time. It is shown that neglecting this reaction has little effect on H distributions, but it leads to O and CHR underestimations (up to ∼ 35–40%) and HO2 and OH overestimations (up to ∼ 50–85%).

Effects of Latitude-Dependent Gravity Wave Source Variations on the Middle and Upper Atmosphere

Atmospheric gravity waves (GWs) are generated in the lower atmosphere by various weather phenomena. They propagate upward, carry energy and momentum to higher altitudes, and appreciably influence the general circulation upon depositing them in the middle and upper atmosphere. We use a three-dimensional first-principle general circulation model (GCM) with implemented nonlinear whole atmosphere GW parameterization to study the global climatology of wave activity and produced effects at altitudes up to the upper thermosphere. The numerical experiments were guided by the GW momentum fluxes and temperature variances as measured in 2010 by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument onboard NASA’s TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite. This includes the latitudinal dependence and magnitude of GW activity in the lower stratosphere for the boreal summer season. The modeling results were compared to the SABER temperature and total absolute momentum flux and Upper Atmosphere Research Satellite (UARS) data in the mesosphere and lower thermosphere. Simulations suggest that, in order to reproduce the observed circulation and wave activity in the middle atmosphere, GW fluxes that are smaller than observed fluxes have to be used at the source level in the lower atmosphere. This is because observations contain a broader spectrum of GWs, while parameterizations capture only a portion relevant to the middle and upper atmosphere dynamics. Accounting for the latitudinal variations of the source appreciably improves simulations.

Evolution of a Mesospheric Bore in a Duct Observed by Ground‐Based Double‐Layer Imagers and Satellite Observations Over the Tibetan Plateau Region

AbstractA mesospheric bore event was observed in the airglow layers of both OH and OI (557.7 nm) bands by two all‐sky airglow imagers in Lhasa (29.66°N, 90.98°E) on the Tibetan Plateau and the Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar‐orbiting Partnership (NPP) satellite on the night of 16–17 December 2014. Simultaneous temperature and OH intensity observations from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the TIMED satellite and wind measurement by a Doppler meteor radar were used to characterize the environment of the bore propagation. A large mesospheric inversion layer was identified from the temperature measured by the SABER instrument. The observed winds in the height range of the OH layer were almost orthogonal to the propagation direction of the mesospheric bore. Both hydraulic jump theory and observations showed that the duct initially shrank followed by an expansion. The duct mainly existed in the OH layer but was weak in the OI layer, as revealed by the double‐layer imaging and satellite observations. The horizontal wavelengths and observed phase speeds of the bore packet decreased as the duct shrank and increased as the duct expanded. The intensity amplitude of the bore packet decreased slowly and then decreased sharply after dissipation. With the variation of the depth of the duct, the bore may have leak out of the duct. The presented study advances the understanding of mesospheric bore evolution and how the ducted environment influences the propagation of the bore.

Correlations Between the Thermosphere's Semiannual Density Variations and Infrared Emissions Measured With the SABER Instrument.

This paper presents measurements of the amplitudes and timings of the combined, annual, and semiannual variations of thermospheric neutral density, and a comparison of these density variations with measurements of the infrared emissions from carbon dioxide and nitric oxide in the thermosphere. The density values were obtained from measurements of the atmospheric drag experienced by the Challenging Minisatellite Payload, Gravity Recovery and Climate Experiment A, Gravity field and Ocean Circulation Explorer, and three Swarm satellites, while the optical emissions were measured with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. These data span a time period of 16 years. A database containing global average densities that were derived from the orbits of about 5,000 objects (Emmert, 2009, https://doi.org/10.1029/2009JA014102, 2015b, https://doi.org/10.1002/2015JA021047) was employed for calibrating these density data. A comparison with the NRLMSISE‐00 model was used to derive measurements of how much the density changes over time due to these seasonal variations. It is found that the seasonal density oscillations have significant variations in amplitude and timing. In order to test the practicality of using optical emissions as a monitoring tool, the SABER data were fit to the measured variations. Even the most simple fit that used only filtered carbon dioxide emissions had good correlations with the measured oscillations. However, the density oscillations were also well predicted by a simple Fourier series, contrary to original expectations. Nevertheless, measurements of the optical emissions from the thermosphere are expected to have a role in future understanding and prediction of the semiannual variations.

Increasing carbon dioxide concentration in the upper atmosphere observed by SABER

AbstractCarbon dioxide measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument between 2002 and 2014 were analyzed to reveal the rate of increase of CO2 in the mesosphere and lower thermosphere. The CO2 data show a trend of ~5% per decade at ~80 km and below, in good agreement with the tropospheric trend observed at Mauna Loa. Above 80 km, the SABER CO2 trend is larger than in the lower atmosphere, reaching ~12% per decade at 110 km. The large relative trend in the upper atmosphere is consistent with results from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS). On the other hand, the CO2 trend deduced from the Whole Atmosphere Community Climate Model remains close to 5% everywhere. The spatial coverage of the SABER instrument allows us to analyze the CO2 trend as a function of latitude for the first time. The trend is larger in the Northern Hemisphere than in the Southern Hemisphere mesopause above 80 km. The agreement between SABER and ACE‐FTS suggests that the rate of increase of CO2 in the upper atmosphere over the past 13 years is considerably larger than can be explained by chemistry‐climate models.

Atomic hydrogen in the mesopause region derived from SABER: Algorithm theoretical basis, measurement uncertainty, and results

Atomic hydrogen (H) is a fundamental component in the photochemistry and energy balance of the terrestrial mesopause region (80–100 km). H is generated primarily by photolysis of water vapor and participates in a highly exothermic reaction with ozone. This reaction is a significant source of heat in the mesopause region and also creates highly vibrationally excited hydroxyl (OH) from which the Meinel band radiative emission features originate. Concentrations (cm−3) and volume mixing ratios of H are derived from observations of infrared emission from the OH (υ = 9 + 8, Δυ = 2) vibration-rotation bands near 2.0 µm made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The algorithms for deriving day and night H are described herein. Day and night concentrations exhibit excellent agreement between 87 and 95 km. SABER H results also exhibit good agreement with observations from the Solar Mesosphere Explorer made nearly 30 years ago. An apparent inverse dependence on the solar cycle is observed in the SABER H concentrations, with the H increasing as solar activity decreases. This increase is shown to be primarily due to the temperature dependence of various reaction rate coefficients for H photochemistry. The SABER H data, coupled with SABER atomic oxygen, ozone, and temperature, enable tests of mesospheric photochemistry and energetics in atmospheric models, studies of formation of polar mesospheric clouds, and studies of atmospheric evolution via escape of hydrogen. These data and studies are made possible by the wide range of parameters measured simultaneously by the SABER instrument.

Technique to produce daily estimates of the migrating diurnal tide using TIMED/SABER and EOS Aura/MLS

A technique to explicitly compute the day-to-day variability of the migrating diurnal tide (DW1) between 20km and 80km on a global scale is presented and analyzed. Our method employs temperature data from two satellite instruments: the MLS (Microwave Limb Sounder) instrument on the EOS (Earth Observing System) Aura spacecraft and the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on the TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) spacecraft. By taking advantage of the four daily solar local time measurements from the two instruments, a least squares fit representing the DW1 is constructed. Consequently, the daily zonal mean, DW1 amplitude and phase are all estimated on a daily basis. Before the implementation of our technique, a comparative analysis between the instrument data sets is conducted. The analysis reveals temperature biases of up to 10K, which are removed to improve our estimates. To evaluate performance, our method is applied to a model atmosphere constructed from tidal fields obtained from the Global Scale Wave Model (GSWM). Performance results indicate that the DW1 is most effectively extracted from the background atmosphere and other tidal components when each latitude circle is well sampled and the local time sampling is evenly spaced. A comparison of our results to the GSWM and past observations support the conclusion that our method produces daily estimates of the DW1 that can be utilized for scientifically useful investigations of short term tidal variability.

Radiative and energetic constraints on the global annual mean atomic oxygen concentration in the mesopause region

AbstractWe present a new approach to constrain and validate atomic oxygen (O) concentrations in the mesopause region (~ 80 to ~ 100 km). In a prior companion paper [Mlynczak et al., ], we presented O‐atom concentrations in the mesopause region inferred from measurements of day ozone and night hydroxyl emission rates made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The approach presented here uses the constraint of global, annual mean energy balance to derive atomic oxygen concentrations, consistent with rates of radiative cooling by carbon dioxide (CO2) and solar heating due to molecular oxygen (O2). The mathematical difference between these cooling and heating rates, on a global annual mean basis, effectively constrains the maximum heating rate for the sum of all other processes. The remaining terms, solar heating due to ozone plus a series of exothermic chemical reactions can be expressed as functions of O. This new approach enables a simple mathematical expression that yields the vertical profile of global annual mean “radiatively constrained” atomic oxygen in the mesopause region. The radiatively constrained atomic oxygen depends only on the CO2 cooling rates, O2 solar heating rates, and standard reaction rate coefficients and enthalpies. Radiative cooling and solar heating rates used in these analyses are derived from measurements made by the SABER instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. There is excellent agreement between the SABER radiatively constrained atomic oxygen and that derived from the SABER ozone and OH emission measurements over most of the mesopause region. Radiatively constrained atomic oxygen represents an upper limit on the global average O‐atom concentration in the mesopause region.

Front‐like behavior in the Arctic wintertime upper stratosphere and lower mesosphere

Synoptic scale disturbances in the Arctic wintertime middle atmosphere are investigated using Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) satellite temperature observations and U.K. Meteorological Office (MetO) assimilated analyses. A representative data set on 13 February 2002 is used as a case study. The observed strong vertical and horizontal thermal gradients in the Arctic winter upper stratosphere and mesosphere are evocative to front‐like behavior in the troposphere. The observations from the SABER instrument and the MetO data of temperature and geopotential suggest that baroclinic instability is a process involved in enhancing the disturbance. Contrary to tropospheric baroclinic development, the ageostrophic circulation associated with the middle atmosphere disturbance is indirect and is driven by eddy momentum flux convergence due to vertically propagating planetary waves. Investigating perturbation geopotential through the Arctic middle atmosphere prior to and during the event, a dominant zonal wave number 1 planetary wave propagating into the upper stratosphere is observed. The observations suggest that, through this planetary wave action, the middle atmosphere becomes highly baroclinic and can promote baroclinic instability that can enhance temperatures to the extreme levels characteristic of these disturbances near the stratopause and in the lower mesosphere.

SABER observations of mesospheric ozone during NH late winter 2002–2009

Observations from the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) satellite show interannual variations of mesospheric ozone in the NH late winter. Ozone in the mid‐January to mid‐March period is significantly different in 2004, 2006, and 2009 than in other years (2002, 2003, 2005, 2007, 2008). The altitudes of the ozone secondary maximum (∼90–95 km), the minimum (∼80 km) and the tertiary maximum (∼72 km) are all lower by 3–5 km during the three anomalous winters. The ozone anomalies indicate enhanced downward motion and are consistent with other observations of unusual profiles of trace species. The ozone perturbations extend to at least 100 km while temperatures above 90 km are within the range found in the other years.

Comparison of nighttime nitric oxide 5.3 μm emissions in the thermosphere measured by MIPAS and SABER

A comparative study of nitric oxide (NO) 5.3 μm emissions in the thermosphere measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectrometer and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) radiometer satellite instruments was conducted for nighttime data collected on 14 June 2003. The agreement between the data sets was very good, within ∼25% over the entire latitude range studied from −58° to + 4°. The MIPAS and SABER data were inverted to retrieve NO volume emission rates. Spectral fitting of the MIPAS data was used to determine the NO(v = 1) rotational and spin‐orbit temperatures, which were found to be in nonlocal thermodynamic equilibrium (non‐LTE) above 110 km. Near 110 km the rotational and spin‐orbit temperatures converged, indicating the onset of equilibrium in agreement with the results of non‐LTE modeling. Because of the onset of equilibrium the NO rotational and spin‐orbit temperatures can be used to estimate the kinetic temperature near 110 km. The results indicate that the atmospheric model NRLMSISE‐00 underestimates the kinetic temperature near 110 km for the locations investigated. The SABER instrument 5.3 μm band filter cuts off a significant fraction of the NO(Δv = 1) band, and therefore modeling of NO is necessary to predict the total band radiance. The needed correction factors were directly determined from the MIPAS data, providing validation of the modeled values used in SABER operational data processing. The correction factors were applied to the SABER data to calculate densities of NO(v = 1). A feasibility study was also conducted to investigate the use of NO 5.3 μm emission data to derive NO(v = 0) densities in the thermosphere.

The 1.5–5-day eastward waves in the upper stratosphere–mesosphere as observed by the Esrange meteor radar and the SABER instrument

Data of neutral meridional wind obtained by the meteor radar at Esrange and data of temperature and pressure measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) spacecraft were studied with respect to a day-to-day atmospheric variability with periods ranging from 1.5 to 5 days. The detailed analysis was carried out for February 2004. Perturbations of the atmospheric parameters at the examined periods appeared mainly as eastward-propagating waves of zonal wavenumbers 1 and 2. We suggested that these waves excited by the jet instability on both flanks of the polar-night jet in the upper stratosphere and mesosphere interact nonlinearly with each other, and this interaction generates secondary waves. The radar observed both primary and secondary waves at mesospheric heights. The data analysis supports this suggestion. Under conditions of weaker instability observed in February 2003 the perturbations of atmospheric parameters of periods ranging from 1.5 to 5 days had smaller amplitudes at heights of the mesosphere than those in February 2004. It was found that the Eliassen-Palm fluxes calculated for the waves generated by the jet instability were mainly downward directed. This result suggests a possible dynamical influence of the mesospheric layers on the lower atmospheric levels.

Spectral analysis of gravity wave activity in SABER temperature data

Since January 2002, the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument has performed continuous measurements from near the tropopause into the thermosphere. For the time period 29 January 2002–31 January 2006, we spectrally analyzed time series of weekly zonal root mean square gravity wave (GW) amplitudes for systematic intra‐annual, annual and inter‐annual GW activity. GWs considered have horizontal wavelengths between 100 km and zonal wave number 6 and vertical wavelengths between 5–30 km. Height‐latitude cross sections of spectral amplitudes and phases between 20–100 km and 55°S–55°N show several relevant oscillations. A strong semiannual variation is evident in the high‐latitude upper stratosphere/mesosphere. Annual components reveal two isolated maxima at mid‐latitudes in both hemispheres, associated with the winter polar vortices, and summertime maxima in the subtropics. Biennial amplitudes in the equatorial stratosphere coincide with the descending westerly shear phase and can be attributed to the quasi‐biennial oscillation.