Thomas Ulich
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View article: Characteristics of Atmospheric Gravity Waves and Medium Scale Traveling Ionospheric Disturbances Derived From EISCAT Measurements
Characteristics of Atmospheric Gravity Waves and Medium Scale Traveling Ionospheric Disturbances Derived From EISCAT Measurements Open
This study investigates the characteristics of medium scale traveling ionospheric disturbances (MSTIDs) relative amplitudes () in the ionospheric E to lower F regions, using the EISCAT VHF radar data measured from 41 daytime runs in years …
View article: Understanding variability in atmospheric electricity measurements at Sodankyla, Finland
Understanding variability in atmospheric electricity measurements at Sodankyla, Finland Open
High latitude measurements of the atmospheric Potential Gradient (PG) can provide valuable information on understanding sources of variability in the Global Electric Circuit (GEC).  The influence of solar activity on electrical proces…
View article: Retrieval of mesospheric temperature from meteor radar and comparison with TIMED/SABER observation
Retrieval of mesospheric temperature from meteor radar and comparison with TIMED/SABER observation Open
Unlike other ground-based optical instruments that are affected by weather conditions, a meteor radar (MR) has the capability of monitoring mesospheric temperature continuously. However, to date, lack of reliable temperature measurements h…
View article: Solar Activity Dependence of Traveling Ionospheric Disturbance Amplitudes Using a Rapid‐Run Ionosonde in High Latitudes
Solar Activity Dependence of Traveling Ionospheric Disturbance Amplitudes Using a Rapid‐Run Ionosonde in High Latitudes Open
We investigated the amplitude of medium scale traveling ionospheric disturbances (MSTIDs, with periods 25–100 min) and their dependence on the solar activity using 16 years data of the rapid run‐ionosonde operating at high latitudes (N, So…
View article: A Deep Learning Approach for Automatic Ionogram Parameters Recognition With Convolutional Neural Networks
A Deep Learning Approach for Automatic Ionogram Parameters Recognition With Convolutional Neural Networks Open
Typical ionosondes operate with >5 min time intervals, which is enough to obtain regular parameters of the ionosphere, but insufficient to observe short‐term processes in the Earth's ionosphere. The key point for this study is to increase …
View article: Effective mass function of radio meteoroids as a modulating factor in determining atmospheric scale height
Effective mass function of radio meteoroids as a modulating factor in determining atmospheric scale height Open
A long-standing problem in meteor science has been the persistent presence of bias in the measured value of atmospheric scale heights obtained from radio meteor echoes. A common practice of fitting a linear function for bias correction fol…
View article: Statistics of Traveling Ionospheric Disturbances at High Latitudes Using a Rapid‐Run Ionosonde
Statistics of Traveling Ionospheric Disturbances at High Latitudes Using a Rapid‐Run Ionosonde Open
The potential of deep learning for the investigation of medium scale traveling ionospheric disturbances (MSTIDs) has been exploited through the Sodankylä rapid‐run ionosonde in this statistical study. The complementing observations of the …
View article: EISCAT_3D – Volumetric Phased-Array Incoherent Scatter Radar in the European Arctic
EISCAT_3D – Volumetric Phased-Array Incoherent Scatter Radar in the European Arctic Open
The EISCAT Scientific Association is currently building the most advanced 3-dimensional imaging radar for atmospheric, ionospheric and near-Earth space investigations. The fully steerable, tri-static, phased-array incoherent scatter radar …
View article: Experiments at the edge of space: balloon flights to the stratosphere
Experiments at the edge of space: balloon flights to the stratosphere Open
Over 1500 balloons are launched every day, from every continent on Earth, to provide forecasting of tropospheric weather. Similar balloons, which can fly to the edge of space (>30 km), can be used for other science projects. Professional s…
View article: Statistics of traveling ionospheric disturbances at high latitudes using a rapid-run Ionosond
Statistics of traveling ionospheric disturbances at high latitudes using a rapid-run Ionosond Open
The potential of deep learning for the investigation of medium scale traveling ionospheric disturbances (MSTIDs) have been exploited through the Sodankylä rapid-run ionosonde in this statistical study. The complementing observations of th…
View article: A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter
A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter Open
The Assimilative Canadian High Arctic Ionospheric Model (A‐CHAIM) is an operational ionospheric data assimilation model that provides a 3D representation of the high latitude ionosphere in Near‐Real‐Time (NRT). A‐CHAIM uses low‐latency obs…
View article: A discourse on the temperature measurement problem using meteor wind radar
A discourse on the temperature measurement problem using meteor wind radar Open
Sodankylä's high latitude location serves an ideal ground for testing more comprehensive physics theory related to radio meteor data. The atmospheric scale height shows significant variation at this latitude.  Also, the observati…
View article: Corrigendum: Multi-instrument observations of the Pajala fireball: Origin, characteristics, and atmospheric implications
Corrigendum: Multi-instrument observations of the Pajala fireball: Origin, characteristics, and atmospheric implications Open
Corrigendum on: Vierinen J, Aslaksen T, Chau JL, Gritsevich M, Gustavsson B, Kastinen D, Kero J, Kozlovsky A, Kvaerna T, Midtskogen S, Näsholm SP, Ulich T, Vegum K and Lester M (2022) Multi-instrument observations of the Pajala fireball: O…
View article: Multi-instrument observations of the Pajala fireball: Origin, characteristics, and atmospheric implications
Multi-instrument observations of the Pajala fireball: Origin, characteristics, and atmospheric implications Open
Meteor observations provide information about Solar System constituents and their influx onto Earth, their interaction processes in the atmosphere, as well as the neutral dynamics of the upper atmosphere. This study presents optical, radar…
View article: Storm‐Time Observations of Traveling Ionospheric Disturbances and Ionospheric Irregularities in East Africa
Storm‐Time Observations of Traveling Ionospheric Disturbances and Ionospheric Irregularities in East Africa Open
In this paper equatorward propagating large scale traveling ionospheric disturbance (LSTID) on 17 March 2015 were investigated using the Statistical Angle‐of‐Arrival and Doppler Method for GPS (SADM‐GPS) radio interferometry technique in d…
View article: A-CHAIM: Near-Real-Time Data Assimilation of the High Latitude Ionosphere with a Particle Filter
A-CHAIM: Near-Real-Time Data Assimilation of the High Latitude Ionosphere with a Particle Filter Open
The Assimilative Canadian High Arctic Ionospheric Model (A-CHAIM) is an operational ionospheric data assimilation model that provides a 3D representation of the high latitude ionosphere in Near-Real-Time (NRT). A-CHAIM uses low-latency obs…
View article: A-CHAIM Test Period September 21st, 2021 through September 29th, 2021
A-CHAIM Test Period September 21st, 2021 through September 29th, 2021 Open
A-CHAIM is an operational, near-real-time ionospheric data assimilation, incorporating measurements from GNSS stations, ionosondes, and vertical TEC from the JASON-3 satellite. Output files from the offline A-CHAIM test run from September …
View article: A-CHAIM Test Period September 21st, 2021 through September 29th, 2021
A-CHAIM Test Period September 21st, 2021 through September 29th, 2021 Open
A-CHAIM is an operational, near-real-time ionospheric data assimilation, incorporating measurements from GNSS stations, ionosondes, and vertical TEC from the JASON-3 satellite. Output files from the offline A-CHAIM test run from September …
View article: Exceptional middle latitude electron precipitation detected by balloon observations: implications for atmospheric composition
Exceptional middle latitude electron precipitation detected by balloon observations: implications for atmospheric composition Open
Energetic particle precipitation leads to ionization in the Earth's atmosphere, initiating the formation of active chemical species which destroy ozone and have the potential to impact atmospheric composition and dynamics down to the tropo…
View article: Comment on acp-2021-737
Comment on acp-2021-737 Open
Abstract. Energetic particle precipitation leads to ionization in the Earth's atmosphere, initiating the formation of active chemical species which destroy ozone and have the potential to impact atmospheric composition and dynamics down to…
View article: Improved method of estimating temperatures at meteor peak heights
Improved method of estimating temperatures at meteor peak heights Open
For 2 decades, meteor radars have been routinely used to monitor atmospheric temperature around 90 km altitude. A common method, based on a temperature gradient model, is to use the height dependence of meteor decay time to obtain a height…
View article: New Earth-space infrastructures enable full-scale monitoring capability
New Earth-space infrastructures enable full-scale monitoring capability Open
<p>The near-Earth environment is continuously changing by disturbances from external and internal sources. A combined research ecosystem is needed to be able to monitor short- and long-term changes and mitigate their societal effects…
View article: Solving the long-standing problem of estimating the atmospheric temperature at 90 km altitude with meteor radar
Solving the long-standing problem of estimating the atmospheric temperature at 90 km altitude with meteor radar Open
<p>For two decades meteor radars have been routinely used to monitor atmospheric temperatures around the 90 km altitude. A common method, based on a temperature-gradient model, is to use the height dependence of meteor decay time to …
View article: Pajala Fireball
Pajala Fireball Open
<p>Meteoroids entering the Earth's atmosphere are associated with a number of phenomena including ablation, ambipolar diffusion, plasma transport, chemical reactions, shock waves, and plasma turbulence. A bright daylight fireball obs…
View article: Improved method of estimating temperatures at meteor peakheights
Improved method of estimating temperatures at meteor peakheights Open
For two decades meteor radars have been routinely used to monitor temperatures around the 90 km altitude. A common method, based on a temperature-gradient model, is to use the height dependence of meteor decay time to obtain a height-avera…
View article: Multi-static spatial and angular studies of polar mesospheric summer echoes combining MAARSY and KAIRA
Multi-static spatial and angular studies of polar mesospheric summer echoes combining MAARSY and KAIRA Open
Polar mesospheric summer echoes (PMSEs) have been long associated with noctilucent clouds (NLCs). For large ice particles sizes and relatively high ice densities, PMSEs at 3 m Bragg wavelengths are known to be good tracers of the atmospher…
View article: Multi-static spatial and angular studies of polar mesosphericsummer echoes combining MAARSY and KAIRA
Multi-static spatial and angular studies of polar mesosphericsummer echoes combining MAARSY and KAIRA Open
Polar mesospheric summer echoes (PMSEs) have been long associated with Noctilucent clouds (NLCs). For large ice particles sizes and relatively high ice densities, PMSE and NLCs have been shown to be highly correlated at 3-m Bragg wavelengt…