Long-term trends of MLT region winds over Central Europe

Abstract. Recent years have shown a continuing interest in studies of the mesosphere-lower thermosphere region at low latitudes, with more than 50 papers dealing specifically with this area published over the past 5 years. Experimental ground-based work has been carried out mainly in South America and the Caribbean, India and the Pacific areas. Subjects of interest include gravity waves, tides and planetary waves, the temperature structure of the mesopause region, with special reference to temperature inversions and the two-level mesopause, sporadic neutral layers and their relationship with ionized layers, the possible effects of the micrometeoroid influx, and long-term trends in the MLT region. Experimental techniques in use include MF, MST and meteor radar, lidar, airglow (including satellite-borne limb-scanning measurements) and rocket-borne instruments. Airglow imaging has shown itself to be a particularly useful technique, mainly for studying gravity wave propagation in the MLT region. This paper will present highlights of recent work and will discuss some of the problems which remain to be resolved.

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Long-term trends of black carbon and particle number concentration in the lower free troposphere in Central Europe

Environmental Sciences Europe ◽

10.1186/s12302-021-00488-w ◽

2021 ◽

Vol 33 (1) ◽

Author(s):

Jia Sun ◽

Markus Hermann ◽

Ye Yuan ◽

Wolfram Birmili ◽

Martine Collaud Coen ◽

...

Keyword(s):

Black Carbon ◽

Central Europe ◽

Mass Concentration ◽

Particle Number ◽

Free Troposphere ◽

Emission Mitigation ◽

Long Term Trends ◽

Aerosol Parameters ◽

Mitigation Policies

Abstract Background The implementation of emission mitigation policies in Europe over the last two decades has generally improved the air quality, which resulted in lower aerosol particle mass, particle number, and black carbon mass concentration. However, little is known whether the decreasing particle concentrations at a lower-altitude level can be observed in the free troposphere (FT), an important layer of the atmosphere, where aerosol particles have a longer lifetime and may affect climate dynamics. In this study, we used data from two high-Alpine observatories, Zugspitze-Schneefernerhaus (ZSF) and Jungfraujoch (JFJ), to assess the long-term trends on size-resolved particle number concentrations (PNCs) and equivalent black carbon (eBC) mass concentration separated for undisturbed lower FT conditions and under the influence of air from the planetary boundary layer (PBL) from 2009 to 2018. Results The FT and PBL-influenced conditions were segregated for both sites. We found that the FT conditions in cold months were more prevalent than in warm months, while the measured aerosol parameters showed different seasonal patterns for the FT and PBL-influenced conditions. The pollutants in the PBL-influenced condition have a higher chance to be transported to high-altitudes due to the mountainous topography, leading to a higher concentration and more distinct seasonal variation, and vice versa. The long-term trends of the measured aerosol parameters were evaluated and the decreased aerosol concentrations were observed for both FT and PBL-influenced conditions. The observed decreasing trends in eBC concentration in the PBL-influenced condition are well consistent with the reported trends in total BC emission in Germany and Switzerland. The decreased concentrations in the FT condition suggest that the background aerosol concentration in the lower FT over Central Europe has correspondingly decreased. The change of back trajectories in the FT condition at ZSF and JFJ was further evaluated to investigate the other possible drivers for the decreasing trends. Conclusions The background aerosol concentration in the lower FT over Central Europe has significantly decreased during 2009–2018. The implementation of emission mitigation policies is the most decisive factor and the decrease of the regional airmass occurrence over Central Europe also has contributed to the decreasing trends.

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Long-term trends in fog occurrence in the Czech Republic, Central Europe

The Science of The Total Environment ◽

10.1016/j.scitotenv.2019.135018 ◽

2020 ◽

Vol 711 ◽

pp. 135018 ◽

Cited By ~ 3

Author(s):

Iva Hůnová ◽

Marek Brabec ◽

Marek Malý ◽

Anna Valeriánová

Keyword(s):

Czech Republic ◽

Central Europe ◽

The Czech Republic ◽

Long Term Trends

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Relationships between long-term trends of air temperature, precipitation, nitrogen nutrition and growth of coniferous stands in Central Europe and Finland

European Journal of Forest Research ◽

10.1007/s10342-008-0233-7 ◽

2008 ◽

Vol 127 (6) ◽

pp. 507-524 ◽

Cited By ~ 19

Author(s):

Karl Heinz Mellert ◽

Jörg Prietzel ◽

Ralf Straussberger ◽

Karl Eugen Rehfuess ◽

Hans Peter Kahle ◽

...

Keyword(s):

Central Europe ◽

Air Temperature ◽

Nitrogen Nutrition ◽

Long Term Trends

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Low-frequency lower E-region wind and reflection height measurements as sensor for climate variability

Advances in Radio Science ◽

10.5194/ars-6-331-2008 ◽

2008 ◽

Vol 6 ◽

pp. 331-335 ◽

Cited By ~ 1

Author(s):

C. Jacobi

Keyword(s):

Oblique Incidence ◽

Lower Thermosphere ◽

Low Frequency ◽

Time Interval ◽

Radio Waves ◽

Reflection Height ◽

E Region ◽

Long Term Trends ◽

Mlt Region

Abstract. Measurements of reflection heights of low-frequency (LF) radio waves at oblique incidence and estimates of mesosphere/lower thermosphere (MLT) region horizontal winds applying the D1 spaced receiver method on LF field strength registrations are analyzed with respect to possible long-term trends and interdecadal variability in the time interval from ~1980 to date. While no clear signal of mesospheric height trend is registered during the last two decades, significant trends of MLT horizontal winds are found. These trends are non-linear, in particular a change of trends around 1990 is found, which is probably connected with changes in tropospheric and stratospheric conditions at that time.

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