In recent years, the need for high-quality long-term mesospheric ozone records has become increasingly evident, as they are essential for understanding chemical, dynamical, and radiative processes in the middle and upper atmosphere and their coupling with the lower layers. Here, we present a new merged dataset of ozone profiles in the middle atmosphere (METEOR-O3), created from several limb-viewing satellite instruments: HALOE, GOMOS, MIPAS, ACE-FTS, MLS, and SOFIE. The merged dataset covers the period from 1991 to 2023 and provides deseasonalized ozone anomalies in 10 degrees latitude bins between 80 degrees S and 80 degrees N, from approximately 22 to 100 km. The deseasonalized ozone anomalies are used for global and seasonal trend analysis. The results show positive upper stratospheric ozone trends in both hemispheres, with magnitudes of 1 %-2 % per decade between 35 and 45 km, indicating continued ozone recovery consistent with previous assessments. In contrast, mesospheric ozone (above similar to 60 km) exhibits negative trends of -1 % to -3 % per decade, with the strongest decreases of about -8 % to -12 % per decade between 80 and 90 km. Seasonal analyses confirm positive trends in the upper stratosphere across all seasons and persistent negative trends in the upper mesosphere, strongest at high latitudes above 80 km. The METEOR-O3 dataset provides the first global, long-term merged record suitable for detailed studies of mesospheric/lower thermospheric ozone variability and trend evaluation, providing valuable information for model validation and assessments of upper atmospheric changes.

Noctilucent clouds (NLC) are the highest clouds on Earth. Also known as polar mesospheric clouds (PMC), they are located just below the mesopause (85–100 km altitude) at high latitudes (>50 degree) and occur only during summer months. The polar summer mesopause is the coldest region of our atmosphere, with temperatures typically below 150 K and occasionally reaching 120 K. NLC are composed of water-ice particles that nucleate on tiny meteoric remnants, known as meteoric smoke. The first known report of NLCs was in 1885, and they have gained attention since then due to their beautiful and dramatic nature. Interest from scientists has been motivated by the numerous mysteries regarding these clouds, including a connection between increasing NLCs and climate change.

Satellite data records of stratospheric water vapour have been compared to balloon-borne frost point hygrometer (FP) profiles that are coincident in space and time. The satellite data records of 15 different instruments cover water vapour data available from January 2000 through December 2016. The hygrometer data are from 27 stations all over the world in the same period. For the comparison, real or constructed averaging kernels have been applied to the hygrometer profiles to adjust them to the measurement characteristics of the satellite instruments. For bias evaluation, we have compared satellite profiles averaged over the available temporal coverage to the means of coincident FP profiles for individual stations. For drift determinations, we analysed time series of relative differences between spatiotemporally coincident satellite and hygrometer profiles at individual stations. In a synopsis we have also calculated the mean biases and drifts (and their respective uncertainties) for each satellite record over all applicable hygrometer stations in three altitude ranges (10–30 hPa, 30–100 hPa, and 100 hPa to tropopause). Most of the satellite data have biases <10 % and average drifts <1 % yr−1 in at least one of the respective altitude ranges. Virtually all biases are significant in the sense that their uncertainty range in terms of twice the standard error of the mean does not include zero. Statistically significant drifts (95 % confidence) are detected for 35 % of the ≈ 1200 time series of relative differences between satellites and hygrometers.

Abstract The Solar Occultation for Ice Experiment (SOFIE) has operated aboard the Aeronomy of Ice in the Mesosphere (AIM) satellite since 2007. SOFIE uses solar occultation to retrieve ozone (O3) profiles from ∼20 to 100 km altitude, typically at polar latitudes. This study validates SOFIE O3 profiles, including error analysis and comparisons with independent observations. Comparisons are made to the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite instruments. SOFIE shows qualitative and quantitative agreement with both data sets between 30 and 70 km and better overall agreement in the northern hemisphere. SOFIE and ACE mean differences are typically within 20% in the 30–70 km altitude range. SOFIE and MIPAS exhibit mean difference values within 30% in the winter and 20% for all other seasons averaged, between ∼30 and 60 km. Seasonal comparisons indicate similar variations in both hemispheres and through all seasons. The comparisons indicate that SOFIE is biased 5%–10% low at 30–70 km altitudes, with greater differences at higher and lower altitudes. The comparisons are challenging due to the low O3 concentrations at high altitudes, the limited number of coincidences, and the large diurnal variation in mesospheric O3 during twilight hours.

The Andes account for the largest source of orographic gravity waves (GWs) in the middle atmosphere. This results from persistent, strong zonal winds at the surface encountering the north-south mountain chain, producing strong orographic lift, and resulting GWs. Here, we consider GWs in the stratosphere and mesosphere above the Andes as observed by the Cloud Imaging and Particle Size instrument, the Solar Occultation for Ice Experiment on the AIM satellite, and the Sounding of the Atmosphere using Broadband Emission Radiometry instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. GW variability is considered in the context of the location of the stratospheric wintertime westerly jet and planetary wave (PW) amplitude and phase. The occurrence of GWs in the middle and upper atmosphere depends not only on tropospheric sources, like the Andes, but also on the background winds through which they propagate. Results suggest that the propagation of GWs into the mesosphere is well correlated with winds throughout the middle and upper stratosphere. PWs cause the westerly jet to move over the Andes, resulting in an increase in GW amplitude throughout the middle and upper stratosphere. The evolution and variability of GWs are tied closely to the phase of the PW-1 and are linked to PW-2 when the PW amplitudes are sufficiently large. GW amplitude, as observed by all three data sets, increases in the upper stratosphere and lower mesosphere when the trough of the PW-1 in the stratosphere is over the Andes. In the Southern Hemisphere, strong wintertime winds continuously flow west to east at mid-latitudes (40 degrees-50 degrees S). As these winds flow over surface features like the Andes Mountains, the air is forced upwards, creating waves in the atmosphere that propagate both horizontally and vertically. These gravity waves (GWs) transport energy from the surface to the upper atmosphere, where they break and deposit their momentum, causing either turbulent mixing, an acceleration of the winds, or the generation of additional waves. The energy deposited from GWs has a significant impact on the circulation in the upper atmosphere, so it is important to understand where they break and to characterize sources of variability. As GWs propagate vertically, they encounter horizontal wind shear associated with a band of strong winds in the middle atmosphere, causing them to turn toward the area of strong winds. The latitude where these strong winds occur can change significantly, driven by planetary-scale waves. This work shows that the occurrence of GWs in the middle atmosphere, observed by several NASA instruments, strongly depends on the amplitude and orientation of the planetary scale waves and the resulting location of the middle atmospheric winds. Gravity waves (GWs) at the stratopause show significant variability over the Andes associated with stratospheric winds and planetary wave (PW) phaseEnhanced GW activity follows the trough of the PW-1 and strong stratospheric winds at mid-southern latitudesGW activity is enhanced over the Andes when the PW trough and the polar night jet are over the Andes

Our solar system is filled with meteoric particles, or cosmic dust, which is either interplanetary or interstellar in origin. Interstellar dust (ISD) enters the heliosphere due to the relative motion of the sun and the interstellar flow. Interplanetary dust (IPD) comes primarily from asteroid collisions or comet sublimation, and comprises the bulk of material entering Earth's atmosphere. This study examines variations in ISD and the IPD flux at Earth using observations from three different satellite techniques. First are size‐resolved in situ meteoroid detections by the Ulysses spacecraft, and second are in situ indirect dust observations by Wind. Third are measurements of meteoric smoke in the mesosphere by the Solar Occultation For Ice Experiment (SOFIE). Wind and Ulysses observations are sorted into the interstellar and interplanetary components. Wind ISD show the anticipated correlation to the 22‐year solar magnetic cycle, and are consistent with model predictions of ISD. Because Wind does not discriminate particle size, the IPD measurements were interpreted using meteoric mass distributions from Ulysses observations and from different models. Wind observations during 2007–2020 indicate a total meteoric influx at Earth of 22 metric tons per day (t d −1 ), in reasonable agreement with long‐term averages from SOFIE (25 t d −1 ) and Ulysses (32 t d −1 ). The SOFIE and Wind influx time series both show an unexpected correlation to the 22‐year solar cycle. This relationship could be an artifact, or may indicate that IPD responds to changes in the solar magnetic field.

We have developed an empirical model of nitric oxide (NO) number density at altitudes from ∼73 km to the exobase, as a function of altitude, latitude, day of year, solar zenith angle, solar activity, and geomagnetic activity. The model is part of the NRLMSIS® 2.1 empirical model of atmospheric temperature and species densities; this upgrade to NRLMSIS 2.0 consists solely of the addition of NO. MSIS 2.1 assimilates observations from six space‐based instruments: UARS/HALOE, SNOE, Envisat/MIPAS, ACE/FTS, Odin/SMR, and AIM/SOFIE. We additionally evaluated the new model against independent extant NO data sets. In this paper, we describe the formulation and fitting of the model, examine biases between the data sets and model and among the data sets, compare with another empirical NO model (NOEM), and discuss scientific aspects of our analysis.

We use the Specified Dynamics version of the Whole Atmosphere Community Climate Model Extended (SD-WACCMX) to model the descent of nitric oxide (NO) and other mesospheric tracers in the extended, elevated stratopause phase of the 2013 sudden stratospheric warming (SSW). The dynamics are specified with a high-altitude version of the Navy Global Environmental Model (NAVGEM-HA). Consistent with our earlier published results, we find that using a high-altitude meteorological analysis to nudge WACCMX allows for a realistic simulation of the descent of lower-thermospheric nitric oxide down to the lower mesosphere, near 60 km. This is important because these simulations only included auroral electrons and did not consider additional sources of NO from higher-energy particles that might directly produce ionization, and hence nitric oxide, below 80–85 km. This suggests that the so-called energetic particle precipitation indirect effect (EPP-IE) can be accurately simulated, at least in years of low geomagnetic activity, such as 2013, without the need for additional NO production, provided the meteorology is accurately constrained. Despite the general success of WACCMX in bringing upper-mesospheric NO down to 55–60 km, a detailed comparison of the WACCMX fields with the analyzed NAVGEM-HA H2O and satellite NO and H2O data from the Solar Occultation for Ice Experiment (SOFIE) and the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) reveals significant differences in the latitudinal and longitudinal distributions at lower altitudes. This stems from the tendency for WACCMX descent to maximize at sub-polar latitudes, and while such sub-polar descent is seen in the NAVGEM-HA analysis, it is more transient than in the WACCMX simulation. These differences are linked to differences in the transformed Eulerian mean (TEM) circulation between NAVGEM-HA and WACCMX, most likely arising from differences in how gravity wave forcing is represented. To attempt to compensate for the differing distributions of model vs. observed NO and to enable us to quantify the total amount of upper-atmospheric NO delivered to the stratopause region, we use potential vorticity and equivalent latitude coordinates. Preliminary results suggest both model and observations are generally consistent with NO totals in the range of 0.1–0.25 gigamoles (GM).

Abstract. We use the Specified Dynamics version of the Whole Atmosphere Community Climate Model Extended (SD-WACCMX) to model the descent of nitric oxide (NO) and other mesospheric tracers in the extended, elevated stratopause phase of the 2013 Sudden Stratospheric Warming (SSW). The dynamics are specified with a high altitude version of the Navy Global Environmental model (NAVGEM-HA). Consistent with our earlier published results, we find that using a high altitude meteorological analysis to nudge WACCMX allows for a realistic simulation of the descent of lower thermospheric nitric oxide down to the lower mesosphere, near 60 km. This is important because these simulations only included auroral electrons, and did not consider additional sources of NO from higher energy particles, for example, medium energy electron precipitation (> 30 keV). This suggests that the so-called energetic particle precipitation indirect effect (EPP-IE) can be accurately simulated, at least in years of low geomagnetic activity, such as 2013, without the need for additional NO production, provided the meteorology is accurately constrained. Despite the general success of WACCMX in simulating mesospheric NO, a detailed comparison of the WACCMX fields with the analyzed NAVGEM-HA H2O and satellite NO and H2O data from the Solar Occultation for Ice Experiment (SOFIE) and the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) reveals significant differences in the latitudinal and longitudinal distributions in the 45–55 km region. This stems from the tendency for WACCMX descent to maximize at sub-polar latitudes and while such sub-polar descent is seen in the NAVGEM-HA analysis, it is more transient than in the WACCMX simulation. These differences are linked to differences in the Transformed Eulerian Mean (TEM) circulation between NAVGEM-HA and WACCMX, most likely arising from small differences in how gravity wave forcing is represented. To attempt to compensate for the differing distributions of model vs. observed NO and to enable us to quantify the total amount of upper atmospheric NO delivered to the stratopause region, we use potential vorticity and equivalent latitude coordinates. Preliminary results suggest both model and observations are generally consistent with NO totals in the range of 0.1–0.25 gigamoles (GM).

Time series of mesospheric temperature and pressure altitude are produced through combining observations by the Halogen Occultation Experiment (HALOE), Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER), and Solar Occultation for Ice Experiment (SOFIE) instruments. Time series of both temperature and pressure altitude are produced through the combination of HALOE/SABER providing 29 years in length and HALOE/SOFIE providing 22 years in length. The different sampling of the three instruments constrains the time series to June in the northern hemisphere and December in the southern hemisphere and 6470 degrees in both hemispheres. We interpret the time series by fitting them to simple descriptions of the variations including solar, intra-hemispheric, inter-hemispheric, and linear trend terms. The inferred intra- and inter-hemispheric terms show that dynamical influences rival solar variability in the mesosphere. We find a robust result that the mesosphere is in general cooling at most altitudes at approximately 1-2 K per decade in response to greenhouse gas increases. That cooling leads to a shrinking of the atmosphere on the order of 100-200 m per decade. The shrinking leads to a reduction in cooling and eventually a warming near 0.005 hPa due to hydrostatic contraction.

Measurements from the Solar Occultation For Ice Experiment (SOFIE) in both hemispheres are used to characterize meteoric smoke in the mesosphere and to estimate the meteoric flux into Earth's atmosphere. New smoke extinction retrievals from sunrise measurements in the Northern Hemisphere (NH) are presented, which complement the previously reported sunset observations in the Southern Hemisphere (SH). The sunrise observations are in good agreement with simulations from the Whole Atmosphere Community Climate Model (WACCM), for both the seasonal and height dependence of smoke in the mesosphere. The SOFIE‐WACCM comparisons assumed that smoke in the mesosphere exists purely as Fe‐rich olivine. This is justified because olivine is detected optically by SOFIE, meteoric ablation is predicted to inject similar quantities of the most abundant elements (Fe, Mg, and Si) into the mesosphere, and olivine is anticipated by theory and laboratory experiments. In addition, the ablated meteoric influx (AMI) and total meteoric influx determined from SOFIE assuming Fe‐rich olivine is in agreement with a recent and independent investigation based on models and observations. SOFIE observations from 2007 to 2021 indicate a global AMI of 7.3 ± 2.2 metric tons per day (t d −1 ), which corresponds to a total influx (ablated plus surviving material) of 24.7 ± 7.3 t d −1 . Finally, the results indicate stronger descent in the NH polar winter mesosphere than in the SH winter. This hemispheric asymmetry at polar latitudes is indicated by smoke and water vapor results from both SOFIE and WACCM.

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Atmospheres. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]Meteoric smoke and meteor influx from global SOFIE observationsAuthorsMark E.HervigiDJohn Maurice CampbellPlaneiDDavid E.SiskindWuhuFengiDCharlesBardeeniDScott MartinBaileySee all authors Mark E. HervigiDCorresponding Author• Submitting AuthorGATS Inc.iDhttps://orcid.org/0000-0003-4914-5211view email addressThe email was not providedcopy email addressJohn Maurice Campbell PlaneiDUniversity of LeedsiDhttps://orcid.org/0000-0003-3648-6893view email addressThe email was not providedcopy email addressDavid E. SiskindNaval Research Laboratoryview email addressThe email was not providedcopy email addressWuhu FengiDUniversity of LeedsiDhttps://orcid.org/0000-0002-9907-9120view email addressThe email was not providedcopy email addressCharles BardeeniDNational Center for Atmospheric Research (UCAR)iDhttps://orcid.org/0000-0002-5330-2788view email addressThe email was not providedcopy email addressScott Martin BaileyVirginia Polytechnical Institute and State University, Blacksburg, VAview email addressThe email was not providedcopy email address

NRLMSIS® 2.0 is an empirical atmospheric model that extends from the ground to the exobase and describes the average observed behavior of temperature, eight species densities, and mass density via a parametric analytic formulation. The model inputs are location, day of year, time of day, solar activity, and geomagnetic activity. NRLMSIS 2.0 is a major, reformulated upgrade of the previous version, NRLMSISE‐00. The model now couples thermospheric species densities to the entire column, via an effective mass profile that transitions each species from the fully mixed region below ~70 km altitude to the diffusively separated region above ~200 km. Other changes include the extension of atomic oxygen down to 50 km and the use of geopotential height as the internal vertical coordinate. We assimilated extensive new lower and middle atmosphere temperature, O, and H data, along with global average thermospheric mass density derived from satellite orbits, and we validated the model against independent samples of these data. In the mesosphere and below, residual biases and standard deviations are considerably lower than NRLMSISE‐00. The new model is warmer in the upper troposphere and cooler in the stratosphere and mesosphere. In the thermosphere, N 2 and O densities are lower in NRLMSIS 2.0; otherwise, the NRLMSISE‐00 thermosphere is largely retained. Future advances in thermospheric specification will likely require new in situ mass spectrometer measurements, new techniques for species density measurement between 100 and 200 km, and the reconciliation of systematic biases among thermospheric temperature and composition data sets, including biases attributable to long‐term changes.

Energetic electron precipitation leads to increased nitric oxide (NO) production in the mesosphere and lower thermosphere. NO distributions in the wintertime, high‐latitude Southern Hemisphere atmosphere during geomagnetic storms are investigated. NO partial columns in the upper mesosphere at altitudes 70–90 km and in the lower thermosphere at 90–110 km have been derived from observations made by the Solar Occultation For Ice Experiment (SOFIE) on board the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE NO measurements during 17 geomagnetic storms in 2008–2014 have been binned into selected geomagnetic latitude and geographic latitude/longitude ranges. The regions above Antarctica showing the largest instantaneous NO increases coincide with high fluxes of 30–300 keV precipitating electrons from measurements by the second‐generation Space Environment Monitor (SEM‐2) Medium Energy Proton and Electron Detector (MEPED) instrument on the Polar‐orbiting Operational Environmental Satellites (POES). Significant NO increases over the Antarctic Peninsula are likely due to precipitation of >30 keV electrons from the radiation belt slot region. NO transport is estimated using Horizontal Wind Model (HWM14) calculations. In the upper mesosphere strong eastward winds (daily mean zonal wind speed ~20–30 m s−1 at 80 km) during winter transport NO‐enriched air away from source regions 1–3 days following the storms. Mesospheric winds also introduce NO‐poor air into the source regions, quenching initial NO increases. Higher up, in the lower thermosphere, weaker eastward winds (~5–10 m s−1 at 100 km) are less effective at redistributing NO zonally.

19 Energetic electron precipitation leads to increased nitric oxide (NO) production in the 20 mesosphere and lower thermosphere. NO distributions in the winter time, high-latitude Southern 21 hemisphere atmosphere during geomagnetic storms are investigated. NO partial columns in the 22 upper mesosphere at altitudes 70–90 km and in the lower thermosphere at 90–110 km have been 23 derived from observations made by the Solar Occultation For Ice Experiment (SOFIE) onboard 24 the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE NO measurements during 25 17 geomagnetic storms in 2008–2014 have been binned into selected geomagnetic latitude and 26 geographic latitude / longitude ranges. The regions above Antarctica showing the largest 27 instantaneous NO increases coincide with high fluxes of 30–300 keV precipitating electrons 28 from measurements by the second generation Space Environment Monitor (SEM-2) Medium 29 Energy Proton and Electron Detector instrument (MEPED) on the Polar orbiting Operational 30 Environmental Satellites (POES). Significant NO increases over the Antarctic Peninsula are 31 likely due to precipitation of 30 keV electrons from the radiation belt slot region. NO transport 32 is estimated using Horizontal Wind Model (HWM14) calculations. In the upper mesosphere 33 strong eastward winds (daily mean zonal wind speed ~20–30 ms -1 at 80 km) during winter 34 transport NO-enriched air away from source regions 1–3 days following the storms. 35 Mesospheric winds also introduce NO poor air into the source regions, quenching initial NO 36 increases. Higher up, in the lower thermosphere, weaker eastward winds (~5–10 ms -1 at 100 km) 37 are less effective at redistributing NO zonally. 38

High-latitude northern hemisphere summer mesospheric gravity wave (GW) activity at PMC altitude (82-86 km) is analyzed from nine years (2007-2015) of Aeronomy of Ice in the Mesosphere (AIM) satellite observation. GW activity is characterized in terms of potential energy per unit mass. A new method is proposed to convert the Ice Water Content (IWC) in Polar Mesospheric Cloud (PMC) observed by the Cloud Imaging and Particle Size (CIPS) experiment on the AIM satellite to temperature using a simple model. These are used with temperatures from the Solar Occultation for Ice Experiment (SOFIE, also onboard the AIM), to derive daily averaged GW potential energy in the northern hemisphere summer. July monthly averaged GW potential energy indicates no relation to the 11-year solar cycle. Daily averaged values indicate a large variability in the 27-day GW oscillation, with positive, negative or no correlation with the 27-day solar rotation during individual summer seasons. However, a superposed epoch analysis using SOFIE GW anomalies indicate a significant negative response to the 27-day solar rotation with a lag of 8-12 days. This 27-day GW response may be related to similar oscillations in the wind, but the exact cause of the 27-day signal in the GW activity is not yet understood.

AbstractThe response of the polar mesosphere to the 11‐year solar cycle is investigated using satellite observations from 1979 to 2018. Solar maximum is expected to cause higher temperatures and lower water vapor in the upper mesosphere, thus reducing the amount of ice in polar mesospheric clouds (PMCs). While PMCs showed a clear anticorrelation with the solar cycle before roughly 2002, this response is absent during recent years. PMCs are controlled by temperature and water vapor, which were examined using mesospheric observations during 1992–2018. The main cause of the diminished solar cycle in PMCs near 68°S and 68°N appears to be a dramatic suppression of the solar cycle response of water vapor. The solar cycle response of temperature also decreases after 2002, but calculations show that the decreased H2O response had more than 3 times the impact on PMCs than the reduction in temperature response.