The mesosphere – lower thermosphere (MLT) contains dust particles made of both ice and refractory materials. Since the MLT overlaps with the heights of meteor ablation, it contains small nanometric particles made of cosmic dust material known as meteor smoke. The smoke particles influence the charge balance and ion chemistry and may serve as condensation nuclei for the formation of the ice particles. The ice particles are observed in summer at mid and high latitudes near the mesopause as noctilucent clouds (NLC) or polar mesospheric clouds (PMC). The presence of ice particles in combination with charge interactions, neutral air turbulence and dynamics also leads to specific radar echoes, known as polar mesospheric summer echoes (PMSE). Radar observations of PMSE and PMC/NLC measurements with cameras or lidar are among the few long-term observations around the summer mesopause. PMC/NLC measurements with satellites, cameras or lidar and PMSE measurements with radar indicate there are changes over the last decades. Aside from the ice and the meteoric smoke, space debris is possibly a third source of dust in the MLT that increases over time.The Maxidusty-2 (MXD2) allowed to measure dust, ions and neutrals from a rocket launched from Andoya, Norway (69.1° N, 16° E) on 5 July 2025 around 8:01 am local time. The MXD2 science payload included four dust in-situ detectors, a neutral gas instrument as well as a Faraday rotation experiment and Langmuir probes to measure electron density. Two independent and different instruments collected dust particles. NLC were observed at that time with the Alomar RMR lidar close by. PMSE were observed at the same time with the MAARSY radar close to the launch site and with the EISCAT radar in Ramfjord (69.6° N, 19.2° E) near Tromsoe at about 130 km distance. All in situ instruments recorded science data. The recovery was successful, and analysis of the collected refractory dust samples is ongoing. An overview of the campaign measurements is given. The initial analysis notably shows that the dust instruments measured a signal at the altitude of the NLC but only small signals at the altitude of higher PMSE layer. We discuss the results in terms of dust charging and the link between dust and the other parameters measured.

The Small Payloads for Investigation of Disturbances in Electrojet by Rockets 2 (SPIDER-2) sounding rocket was launched from Esrange, Sweden, on the 19th of February 2020 at 23:14 UT. It traversed a pulsating aurora event, deploying eight free falling units which provided in situ multi-point measurements of the electric field, magnetic field and plasma parameters. In this article, the measured plasma parameters have been analyzed and compared with each other and with optical measurements obtained by ground based instrumentation. Peaks in electron density, thermal ion flux and optical emission have been found in the E region. Electron density profiles have been derived from the data collected by the Langmuir probes in two free falling units, the electron probes in the main rocket and the wave propagation experiment. A generally good agreement has been found among the different measurements in the up-leg of the trajectory, while the effect of the rocket wake was evident in the down-leg. The observed electron density profile has been found to agree with an incoming flux of high energetic electrons with energies around 20 keV. Auroral pulsations with a periodicity of 1-2 s have been recorded by an onboard photometer, a ground-based high speed camera, and the in situ thermal ion flux. The percentages of variation between the ON and OFF phases of the pulsations have been quantified for these quantities. The brightness measured by the photometer varies up to 68%, while the thermal ion flux measurements show only a 2.5% variation.

We present mass spectroscopic in situ data from rocket flights of two improved ion mass spectrometers in the mesosphere and lower thermosphere region. The instruments were optimized to detect large ions with a mass-to-charge ratio (m/z, mass) of up to m/z 2000 and 20 000 respectively, for analysis of meteor smoke particles. The flights were performed in the framework of the polar mesospheric winter echo (PMWE) campaigns, initiated and coordinated by the Leibniz Institute of Atmospheric Physics (IAP), to investigate polar mesospheric winter radar echoes in Andøya (Norway) in 2018 and 2021. Both flights were successful and allowed the mass number and chemical composition of charged meteor smoke particles to be investigated. We found a complex and diverse composition of positively and negatively charged molecules and particles within our mass range in a region that is notoriously difficult to get mass spectroscopic data from. While at altitudes below 85 km we observed negatively charged particles of up to several thousands of atomic mass units, above this altitude we found possible building blocks of these large particles that form right after their ablation from the parent meteorite material. In the first flight we detected no positively charged particles above m/z 100 and a difficult-to-interpret signal for negatively charged particles beyond our mass range of m/z 2000. In the second flight, however, we detected positively charged particles between around m/z 180 and 350 and a number of different negatively charged particles up to m/z 5500. Due to the very large mass range of m/z 20 000 used in the second flight and the subsequent lower mass resolution, unambiguous mass identification is not possible. A particular interesting pattern was found at 80.8 km of a compound that seems to double its mass around m/z 225, 450, 900 and 1800. Comparing our findings to proposed meteor smoke particle compounds by other authors, our observations would be consistent with magnetite, fayalite and forsterite. However, other possible compounds cannot be excluded.

Throughout the winter, extreme circumpolar wind patterns are found in the altitude range of 30 to 70 km, reaching wind speeds up to 500 km/h. The circumpolar wind patterns form the Stratospheric Polar Vortex. In the Northern Hemisphere, weather extremes are known to be linked to distortions of the Polar Vortex. Recently, studies using observations and modelling have indicated that the extreme winds at the Polar Vortex Edge also play a crucial role in multistep upward coupling through gravity waves. Variations in the wind profiles affect gravity wave propagation and lead to wave generation and breakdown. Direct measurements of the mean winds and waves at the Polar Vortex Edge are rare and technically challenging. We use lidar and radar instruments to measure temperature, wind, and the occurrence of layered phenomena over northern Norway (ALOMAR, 69°N) and northern Germany (Kühlungsborn, 54°N). Using more than 10 years of measurements, we have collected a unique dataset, which contains measurements both inside and outside the Polar Vortex. These observations are used to explore upward- and downward-propagating gravity waves in the complex dynamical setting near the Polar Vortex Edge. These unique wave-vortex interactions play a role in coupling layers above and below, and link large-scale flow to turbulence, frequently observed as layered phenomena, such as Polar Mesosphere Winter Echoes. The link between waves, turbulence, and the polar vortex will be discussed using observations and model data.

Using the Doppler-Rayleigh lidars at Kühlungsborn (54°N, 12°E) and ALOMAR (69° N, 16° E), we have obtained simultaneous vertical profiles of horizontal wind and temperature on the poleward flank of the Polar Night Jet. This study presents a case where a modified hodograph technique was applied to identify quasi-monochromatic gravity waves within the high wind speed regime of the jet's flank. Our analysis reveals a reduction in gravity wave kinetic and potential energy within the core of the Polar Night Jet for both upward- and downward-propagating waves, attributed to a strong wind shear layer.We will present a statistical overview of intrinsic gravity wave parameters for all resolved waves in the observation. We will demonstrate our ability to resolve low amplitude waves in the lidar observation down to amplitudes of ~0.5 K in the stratosphere.As an extension, we will show preliminary attempts to estimate energy fluxes from the lidar data using structure-function and compared these results with hodograph-derived gravity wave energies to investigate turbulent energy transfer rates within the Polar Night Jet.

Abstract. We present data from flights of two improved ion mass spectrometers in the mesosphere and lower thermosphere region. The instruments were optimized to detect large ion masses of up to m/z 2000 and 20000 respectively, for analysis of meteor smoke particles. The flights were performed in the frame of the PMWE campaign, initiated and coordinated by IAP/Kühlungsborn, to investigate polar mesospheric winter radar echoes in Andøya/Norway in 2018 and 2021. Both flights were successful and allow to investigate the mass number and chemical composition of charged meteor smoke particles. We found a complex and divers composition of positively and negatively charged molecules and particles. While at altitudes below 85 km we observed negatively charged particles of up to several thousands of atomic mass units, above this altitude we found possible building blocks of these large particles that form right after their ablation from the parent meteorite material. While in the first flight we detected no positively charged molecules and ion clusters above m/z 100, we measured positive and negative ions with masses up to around m/z 400 in the second flight. Due to the very large mass range of m/z 20000 used in the second flight and the subsequent lower mass resolution, unambiguous mass identification is not possible. Comparing our findings to proposed meteor smoke particle compounds by other authors, our observations would be consistent with Magnetite, Fayalite and Forsterite. However, other possible compounds cannot be excluded.

AbstractChemical heating rates were derived from three of the most significant reactions based on the analysis of common volume rocket-borne measurements of temperature, atomic oxygen densities, and neutral air densities. This is one of the first instances of the retrieval of nighttime chemical heat through the utilization of non-emissive observations of atomic oxygen concentrations, obtained through in situ measurements, performed at the Andøya Space Center (69°N, 16°E) at 01:44:00 UTC on 5 March 2015. Furthermore, we determine the heating efficiency for one of the most significant reactions of atomic hydrogen with ozone and illustrate the methodology for such calculations based on known atomic oxygen and temperature. Subsequently, using ozone values obtained from satellite observations, we retrieved odd-hydrogens and total chemical heat. Finally, we compared the retrieved chemical heat with the heat from turbulent energy dissipation. Our findings reveal that the vertically averaged chemical heat is greater than the heat from turbulent energy dissipation throughout the entire mesopause region during nocturnal conditions. The heating rates of turbulent energy dissipation may exceed the chemical heating rates only in narrow peaks, several hundred meters wide. Graphical Abstract

The polar night jet, i.e., the edge of the polar vortex, maximises in the altitude range of 30 km to 70 km. The polar vortex is known to affect even underlying layers and the weather. The polar night jet shows the highest mean wind speeds observed in the atmosphere and likely plays an important role in multi-step vertical coupling not only from the ground, but also from the upper atmosphere downward.Direct measurements of the polar night jet’s extreme atmospheric motion are rare and limited to a few rocket soundings or locations with dedicated remote sensing techniques. We operate lidar and radar instruments capable of measuring temperatures and winds above northern Norway (ALOMAR, 69°N) and northern Germany (Kühlungsborn, 54°N). The instruments have observed the atmosphere frequently inside and outside the Polar Vortex for more than 10 years.Using lidar measurements of temperatures and winds allows for studying up- and downward-propagating gravity waves in complicated dynamical situations that are often found at the polar vortex edge. Observing simultaneously up- and downward propagating waves may indicate gravity wave breakdown as well as the generation of secondary gravity waves and turbulence. Turbulence is frequently detected using the MAARSY VHF radar. So called Polar Mesosphere Winter Echoes (PMWE) are observed if sufficient ionisation and turbulence exist.We will discuss the relationship between waves, turbulence, and the polar vortex based on lidar and radar observations.

The spectral model turbulence analysis technique is widely used to derive kinetic energy dissipation rates of turbulent structures ( ɛ ) from different in situ measurements in the Earth's atmosphere. The essence of this method is to fit a model spectrum to measured spectra of velocity or scalar quantity fluctuations and thereby to derive ɛ only from wavenumber dependence of turbulence spectra. Owing to the simplicity of spectral model of Heisenberg (1948), https://doi.org/10.1007/bf01668899 its application dominates in the literature. Making use of direct numerical simulations which are able to resolve turbulence spectra down to the smallest scales in dissipation range, we advance the spectral model technique by quantifying uncertainties for two spectral models, the Heisenberg (1948), https://doi.org/10.1007/bf01668899 and the Tatarskii (1971) model, depending on (a) resolution of measurements, (b) stage of turbulence evolution, (c) model used. We show that the model of Tatarskii (1971) can yield more accurate results and reveals higher sensitivity to the lowest ɛ ‐values. This study shows that the spectral model technique can reliably derive ɛ if measured spectra only resolve half‐decade of power change within the viscous (viscous‐convective) subrange. In summary, we give some practical recommendations on how to derive the most precise and detailed turbulence dissipation field from in situ measurements depending on their quality. We also supply program code of the spectral models used in this study in Python, IDL, and Matlab.

Polar mesosphere winter echoes (PMWE) are relatively strong radar returns which are regularly observed by mesosphere/stratosphere/troposphere (MST) radars at high latitudes in winter. A sounding rocket project PMWE aimed at investigation of this phenomenon by means of high resolution in situ measurements of all the relevant parameters inside and around the volume probed by the MAARSY radar. Two sounding rocket campaigns were conducted at the Andøya Space (AS, 69 °N, 16 °E) in April 2018 and October 2021, respectively. Two instrumented sounding rockets were launched during each rocket campaing. Both EISCAT in Tromsø and SAURA radar located near the launch site were running throughout the campaign periods. RMR-lidar successfully measured temperature and wind fields on the day of rocket launches in October 2021. In this paper we give an overview and some details of the measurements conducted during the two rocket campaigns and discuss first results.

Simultaneous measurements of rocket-borne and ground-based instruments in a common volume were performed from Andoya, Norway (69 degrees N, 16 degrees E) in frame of the recent PMWE-project, devoted to clarify the formation mechanism behind polar mesosphere winter echoes (PMWE). This article focuses on measurements of April, 13th 2018. Despite low solar activity, we observe several radar echoes, giving the launch criterion. Combining precise in-situ ionization gauge and wave propagation measurements with ground-based radar measurements on 53.5 and 3.17 MHz, as well as lidar, we were able to measure key parameters of PMWE formation. Carefully analyzing the atmospheric background (i.e., temperature, viscosity, Brunt-Vaisala frequency, and scale heights of electron and neutral density), deriving turbulence parameters by means of radar and rocket, as well as estimating particle sizes of meteor smoke particles (MSP), we got a deep insight into the physical processes behind the PMWE phenomenon. Measurements clearly show that the coherent structures in refractive index variations (forming PMWE) are accompanied by neutral air turbulence, which is reflected in small-scale structures (down to some meters) of neutral and electron density. We analyze and discuss the temporal development of the radar echos by means of spectral width and wind measurements. We show that the behavior of the structures under investigation together with the atmospheric background is consistent with the interpretation, that PMWE were created by turbulence. Furthermore, it becomes clear that charged Meteor Smoke Particles (MSP) and background electron density can only enhance SNR, while turbulence is a prerequisite for their formation.

Based on common volume rocket-borne measurements of temperature, densities of atomic oxygen and neutral air, we derived O(D-1) nighttime concentrations and corresponding Atmospheric band emission (762 nm). This is one of the first retrievals of the nighttime O(D-1) concentration. Recently, Kalogerakis, Sharma and co-workers have suggested a new production path of O(D-1) based on the reaction of vibrationally excited OH and O. We calculate Atmospheric band volume emission related to the population of O-2(b(1)Sigma(+)(g)) from O(D-1) and compare with total Atmospheric band emissions observed during the same rocket launch. This allows an estimation of the relative contribution of the new Kalogerakis-Sharma mechanism (KSM) to the total Atmospheric band emission. The concentration of O(D-1) due to KSM amounts to several tens cm(-3) with a peak around 95 km. The KSM gives an essential contribution to the total Atmospheric band volume emission (762 nm). Additionally, we illustrate analytically that the expressions for volume emission by the new KSM and the traditional two-step mechanism have similar functional dependences on the atmospheric concentrations of O and O-2. This causes an ambiguity, when interpreting Atmospheric band observations in terms of the one mechanism or the other.

We present a novel rocket-borne ion mass spectrometer named ROMARA (ROcket-borne MAss spectrometer for Research in the Atmosphere) for measuring atmospheric positive and negative ions (atomic, molecular and cluster ions) and positively and negatively charged meteor smoke particles. Our ROMARA instrument has, compared to previous rocket-borne ion mass spectrometers, a markedly larger mass range of up to m/z 2000 and a larger sensitivity, particularly for meteor smoke particle detection. The major objectives of this first ROMARA flight included the following: a functional test of the ROMARA instrument, measurements between 55 and 121 km in the mass range of atmospheric positive and negative ions, a first attempt to conduct mass spectrometric measurements in the mass range of meteor smoke particles with mass-to-charge ratios up to m/z 2000, and measurements inside a polar mesospheric winter echo layer as detected by ground-based radar. Our ROMARA measurements took place on the Arctic island of Andøya, Norway, at around noon in April 2018 and represented an integral part of the polar mesospheric winter radar echo (PMWE) rocket campaign. During the rocket flight, ROMARA was operated in a measurement mode, offering maximum sensitivity and the ability to qualitatively detect total ion signatures even beyond its mass-resolving mass range. On this first ROMARA flight we were able to meet all of our objectives. We detected atmospheric species including positive atomic, molecular and cluster ions along with negative molecular ions up to about m/z 100. Above m/z 2000, ROMARA measured strong negative-ion signatures, which are likely due to negatively charged meteor smoke particles.

A first sounding rocket campaign dedicated to investigate the creation mechanism of Polar Mesosphere Winter Echoes (PMWE) was conducted in April 2018 from the north Norwegian Andøya Space Center (69°N, 16°E). Two instrumented sounding rockets were launched on 13th and 18th of April under PMWE and no-PMWE conditions, respectively.In this paper we give a brief summary of our current knowledge of PMWE and an overview of the PMWE sounding rocket mission. We describe and discuss some results of combined in situ and ground-based measurements which allow to check the existing PMWE theories.Our measurements clearly show that the coherent structures in refractive index variations (forming PMWE) are accompanied by neutral air turbulence, which is reflected in small-scale structures (down to some meters) of neutral and electron density. We show that the behavior of the structures under investigation together with the atmospheric background is consistent with the interpretation, that PMWE were created by turbulence. Rocket measurements ultimately show that polar winter mesosphere is abounded with meteor smoke particles (MSP) and intermittent turbulent layers. Furthermore, it becomes clear that charged Meteor Smoke Particles (MSP) and background electron density can only enhance SNR, while turbulence is a prerequisite for their formation.

Polar Mesospheric Winter Echoes (PMWE) have been observed by VHF radars for quite some years. Until now, most of the studies were focussed on either major events, that occurred during solar and geomagnetic severely distorted conditions or statistical parameters like their seasonal and interannual occurrence rates as well as altitude distributions were investigated. However, especially the origin of PMWE and underlying processes are still under debate and further observations aim to contribute to this question. Recent PMWE observations with the MAARSY VHF radar included experiments using multiple beam directions to investigate the spatial structure and evolution of PMWE. Within this study we present results of MAARSY radar observations of PMWE layers complemented by simultaneous measurements by the Saura HF radar, located less than 20km apart. Major products of the Saura radar are horizontal winds and electron density within the D region. These parameters are important for both the formation and visibility of PMWE. The spectral width and localization of VHF and HF radar echoes for the presence of PMWE are analyzed and compared in the context of turbulence. Furthermore, observations during the solar minimum for the season 2019/2020 appear to be a suitable period to deepen the investigation of background conditions, excluding intensive geomagnetic disturbances.

Two experimental sounding rockets were launched from Andøya Space Center (Norway) devoted to investigate the phenomenon of polar mesospheric winter echoes (PMWE). PMWE are relatively strong radar returns during winter, observed at various frequencies (e.g. ≈ 50 MHz Maarsy or ≈ 224 MHz with EISCAT). Despite possible tracing capabilities for dynamics in the Meso- sphere over a wide annual and altitudinal extend, the formation process is still not understood. To clarify the formation mechanism and proof theories, an experimental setup consisting of two rocket payloads were designed. Aim- ing for measuring neutral air temperature, relative and absolute densities of plasma constituents (electrons, ions, charged aerosols), neutral air and trace gases as well as turbulence. In-situ measurements were complemented by ground based measurements of multiple radars and lidars. We show results from contemporaneous multi instrumental in-situ measure- ments and ground based observations based on the first part of the PMWE- Project and discuss them in the context of most relevant theories.

This paper presents simultaneous temperature measurements by three independent instruments during the WADIS-2 rocket campaign in northern Norway (69∘ N, 14∘ E) on 5 March 2015. Vertical profiles were measured in situ with the CONE instrument. Continuous mobile IAP Fe lidar (Fe lidar) measurements during a period of 24 h, as well as horizontally resolved temperature maps by the Utah State University (USU) Advanced Mesospheric Temperature Mapper (AMTM) in the mesopause region, are analysed. Vertical and horizontal temperature profiles by all three instruments are in good agreement. A harmonic analysis of the Fe lidar measurements shows the presence of waves with periods of 24, 12, 8, and 6 h. Strong waves with amplitudes of up to 10 K at 8 and 6 h are found. The 24 and 12 h components play only a minor role during these observations. In contrast only a few short periodic gravity waves are found. Horizontally resolved temperatures measured with the AMTM in the hydroxyl (OH) layer are used to connect the vertical temperature profiles. In the field of view of 200 km×160 km only small deviations from the horizontal mean of the order of 5 K are found. Therefore only weak gravity wave signatures occurred. This suggests horizontal structures of more than 200 km. A comparison of Fe lidar, rocket-borne measurements, and AMTM temperatures indicates an OH centroid altitude of about 85 km.

Absolute profiles of atomic oxygen number densities with high vertical resolution have been determined in the mesosphere–lower thermosphere (MLT) region from in situ measurements by several rocket-borne solid electrolyte sensors. The amperometric sensors were operated in both controlled and uncontrolled modes and with various orientations on the foredeck and aft deck of the payload. Calibration was based on mass spectrometry in a molecular beam containing atomic oxygen produced in a microwave discharge. The sensor signal is proportional to the number flux onto the electrodes, and the mass flow rate in the molecular beam was additionally measured to derive this quantity from the spectrometer reading. Numerical simulations provided aerodynamic correction factors to derive the atmospheric number density of atomic oxygen from the sensor data. The flight results indicate a preferable orientation of the electrode surface perpendicular to the rocket axis. While unstable during the upleg, the density profiles measured by these sensors show an excellent agreement with the atmospheric models and photometer results during the downleg of the trajectory. The high spatial resolution of the measurements allows for the identification of small-scale variations in the atomic oxygen concentration.

Abstract. In April 2018 the PMWE1 sounding rocket campaign was conducted at the Andøya Space Center involving coordinated measurements with rockets and ground instruments to measure parameters relevant for testing of the existing theories of polar mesospheric winter echo (PMWE) formation. The Middle Atmosphere Alomar Radar System (MAARSY) was operated to detect PMWE with multiple beam directions to detect favorable launch conditions. A dedicated experiment configuration with five different beam positions was used to point the radar beam along the planned trajectory of the payload. This special radar experiment allowed to obtain basic information about the spatial structure of the PMWE and its dynamical behavior around the flight of the two rockets. PMWE with signal strengths between 10−17 and 10−15 m−1 have been observed by MAARSY during the whole campaign period, starting with a moderate occurrence at the beginning which decreased towards the end of the campaign. Furthermore real common-volume observations by rocket instruments and radar soundings have been carried out at PMWE altitudes on up-leg and down-leg of the rocket flights. The Saura MF radar was operated during both flights probing the mesosphere with a multiple beam scan experiment to derive horizontal winds and electron density profiles. The obtained PMWE characteristics as signal strength and spectral width of the received radar signals as well as estimated horizontal winds and electron densities are presented with particular emphasis to the launch times of the sounding rockets.

Abstract. In this paper we present an overview of measurements conducted during the WADIS-2 rocket campaign. We investigate the effect of small-scale processes like gravity waves and turbulence on the distribution of atomic oxygen and other species in the MLT region. Our analysis suggests that density fluctuations of atomic oxygen are coupled to fluctuations of other constituents, i.e., plasma and neutrals. Our measurements show that all measured quantities, including winds, densities, and temperatures, reveal signatures of both waves and turbulence. We show observations of gravity wave saturation and breakdown together with simultaneous measurements of generated turbulence. Atomic oxygen inside turbulence layers shows two different spectral behaviors, which might imply change of its diffusion properties.