2015, Matthias, V., Shepherd, T.G., Hoffmann, P., Rapp, M.

Sudden stratospheric warmings (SSWs) are the most prominent vertical coupling process in the middle atmosphere, which occur during winter and are caused by the interaction of planetary waves (PWs) with the zonal mean flow. Vertical coupling has also been identified during the equinox transitions, and is similarly associated with PWs. We argue that there is a characteristic aspect of the autumn transition in northern high latitudes, which we call the "hiccup", and which acts like a "mini SSW", i.e. like a small minor warming. We study the average characteristics of the hiccup based on a superimposed epoch analysis using a nudged version of the Canadian Middle Atmosphere Model, representing 30 years of historical data. Hiccups can be identified in about half the years studied. The mesospheric zonal wind results are compared to radar observations over Andenes (69° N, 16° E) for the years 2000–2013. A comparison of the average characteristics of hiccups and SSWs shows both similarities and differences between the two vertical coupling processes.

2015, Placke, M., Hoffmann, P., Rapp, M.

Gravity waves (GWs) greatly influence the background state of the middle atmosphere by imposing their momentum on the mean flow upon breaking and by thus driving, e.g., the upper mesospheric summer zonal wind reversal. In this situation momentum is conserved by a balance between the vertical divergence of GW momentum flux (the so-called GW drag) and the Coriolis acceleration of the mean meridional wind. In this study, we present first quantitative mean annual cycles of these two balancing quantities from the medium frequency Doppler radar at the polar site Saura (SMF radar, 69° N, 16° E). Three-year means for 2009 through 2011 clearly show that the observed zonal momentum balance between 70 and 100 km with contributions from GWs only is fulfilled during summer when GW activity is strongest and more stable than in winter. During winter, the balance between GW drag and Coriolis acceleration of the mean meridional wind is not existent, which is likely due to the additional contribution from planetary waves, which are not considered by the present investigation. The differences in the momentum balance between summer and winter conditions are additionally clarified by 3-month mean vertical profiles for summer 2010 and winter 2010/2011.

2018-4-3, Li, Qiang, Rapp, Markus, Stober, Gunter, Latteck, Ralph

The Middle Atmosphere Alomar Radar System (MAARSY) installed at the island of Andøya has been run for continuous probing of atmospheric winds in the upper troposphere and lower stratosphere (UTLS) region. In the current study, we present high-resolution wind measurements during the period between 2010 and 2013 with MAARSY. The spectral analysis applying the Lomb–Scargle periodogram method has been carried out to determine the frequency spectra of vertical wind velocity. From a total of 522 days of observations, the statistics of the spectral slope have been derived and show a dependence on the background wind conditions. It is a general feature that the observed spectra of vertical velocity during active periods (with wind velocity > 10 m s−1) are much steeper than during quiet periods (with wind velocity < 10 m s−1). The distribution of spectral slopes is roughly symmetric with a maximum at −5/3 during active periods, whereas a very asymmetric distribution with a maximum at around −1 is observed during quiet periods. The slope profiles along altitudes reveal a significant height dependence for both conditions, i.e., the spectra become shallower with increasing altitudes in the upper troposphere and maintain roughly a constant slope in the lower stratosphere. With both wind conditions considered together the general spectra are obtained and their slopes are compared with the background horizontal winds. The comparisons show that the observed spectra become steeper with increasing wind velocities under quiet conditions, approach a spectral slope of −5/3 at a wind velocity of 10 m s−1 and then roughly maintain this slope (−5/3) for even stronger winds. Our findings show an overall agreement with previous studies; furthermore, they provide a more complete climatology of frequency spectra of vertical wind velocities under different wind conditions.

2018, Kundzewicz, Zbigniew W., Piniewski, Mikołaj, Mezghani, Abdelkader, Okruszko, Tomasz, Pińskwar, Iwona, Kardel, Ignacy, Hov, Øystein, Szcześniak, Mateusz, Szwed, Małgorzata, Benestad, Rasmus E., Marcinkowski, Paweł, Graczyk, Dariusz, Dobler, Andreas, Førland, Eirik J., O’Keefe, Joanna, Choryński, Adam, Parding, Kajsa M., Haugen, Jan Erik

The present paper offers a brief assessment of climate change and associated impact in Poland, based on selected results of the Polish–Norwegian CHASE-PL project. Impacts are examined in selected sectors, such as water resources, natural hazard risk reduction, environment, agriculture and health. Results of change detection in long time series of observed climate and climate impact variables in Poland are presented. Also, projections of climate variability and change are provided for time horizons of 2021–2050 and 2071–2100 for two emission scenarios, RCP4.5 and RCP8.5 in comparison with control period, 1971–2000. Based on climate projections, examination of future impacts on sectors is also carried out. Selected uncertainty issues relevant to observations, understanding and projections are tackled as well.

2013, Szewczyk, A., Strelnikov, B., Rapp, M., Strelnikova, I., Baumgarten, G., Kaifler, N., Dunker, T., Hoppe, U.-P.

From 19 November to 19 December 2010 the fourth and final ECOMA rocket campaign was conducted at Andøya Rocket Range (69 N, 16 E) in northern Norway. We present and discuss measurement results obtained during the last rocket launch labelled ECOMA09 when simultaneous and true common volume in situ measurements of temperature and turbulence supported by ground-based lidar observations reveal two Mesospheric Inversion Layers (MIL) at heights between 71 and 73 km and between 86 and 89 km. Strong turbulence was measured in the region of the upper inversion layer, with the turbulent energy dissipation rates maximising at 2 W kg-1. This upper MIL was observed by the ALOMAR Weber Na lidar over the period of several hours. The spatial extension of this MIL as observed by the MLS instrument onboard AURA satellite was found to be more than two thousand kilometres. Our analysis suggests that both observed MILs could possibly have been produced by neutral air turbulence.

2010, Kumar, G.K., Hocking, W.K.

Mean winds and tides in the northern polar Mesosphere and Lower Thermosphere (MLT) have been studied using meteor radars located at Resolute Bay (75° N, 95° W) and Yellowknife (62.5° N, 114.3° W). The measurements for Resolute Bay span almost 12 years from July 1997 to February 2009 and the Yellowknife data cover 7 years from June 2002 to October 2008. The analysis reveals similar wind flow over both sites with a difference in magnitude. The summer zonal flow is westward at lower heights, eastward at upper heights and the winter zonal flow is eastward at all heights. The winter meridional flow is poleward and sometimes weakly equatorward, while non winter months show equatorward flow, with a strong equatorward jet during mid-summer months. The zonal and meridional winds show strong interannual variation with a dominant annual variation as well as significant latitudinal variation. Year to year variability in both zonal and meridional winds exists, with a possible solar cycle dependence. The diurnal, semidiurnal and terdiurnal tides also show large interannual variability and latitudinal variation. The diurnal amplitudes are dominated by an annual variation. The climatological monthly mean winds are compared with CIRA 86, GEWM and HWM07 and the climatological monthly mean amplitudes and phases of diurnal and semidiurnal tides are compared with GSWM00 predictions. The GEWM shows better agreement with observations than the CIRA 86 and HWM07. The GSWM00 model predictions need to be modified above 90 km. The agreements and disagreements between observations and models are discussed. © 2010 Author(s).

2012, Stober, G., Latteck, R., Rapp, M., Singer, W., Zecha, M.

MST radars have been used to study the troposphere, stratosphere and mesosphere over decades. These radars have proven to be a valuable tool to investigate atmospheric dynamics. MAARSY, the new MST radar at the island of Andøya uses a phased array antenna and is able to perform spaced antenna and Doppler measurements at the same time with high temporal and spatial resolution. Here we present first wind observations using the initial expansion stage during summer 2010. The tropospheric spaced antenna and Doppler beam swinging experiments are compared to radiosonde measurements, which were launched at the nearby Andøya Rocket Range (ARR). The mesospheric wind observations are evaluated versus common volume meteor radar wind measurements. The beam steering capabilities of MAARSY are demonstrated by performing systematic scans of polar mesospheric summer echoes (PMSE) using 25 and 91 beam directions. These wind observations permit to evaluate the new radar against independent measurements from radiosondes and meteor radar measurements to demonstrate its capabilities to provide reliable wind data from the troposphere up to the mesosphere.

2019, Wilhelm, S., Stober, G., Brown, P.

We report on long-term observations of atmospheric parameters in the mesosphere and lower thermosphere (MLT) made over the last 2 decades. Within this study, we show, based on meteor wind measurement, the long-term variability of winds, tides, and kinetic energy of planetary and gravity waves. These measurements were done between the years 2002 and 2018 for the high-latitude location of Andenes (69.3°N, 16°E) and the mid-latitude locations of Juliusruh (54.6°N, 13.4°E) and Tavistock (43.3°N, 80.8°W). While the climatologies for each location show a similar pattern, the locations differ strongly with respect to the altitude and season of several parameters. Our results show annual wind tendencies for Andenes which are toward the south and to the west, with changes of up to 3°m s-1 per decade, while the mid-latitude locations show smaller opposite tendencies to negligible changes. The diurnal tides show nearly no significant long-term changes, while changes for the semidiurnal tides differ regarding altitude. Andenes shows only during winter a tidal weakening above 90°km, while for the Canadian Meteor Orbit Radar (CMOR) an enhancement of the semidiurnal tides during the winter and a weakening during fall occur. Furthermore, the kinetic energy for planetary waves showed strong peak values during winters which also featured the occurrence of sudden stratospheric warming. The influence of the 11-year solar cycle on the winds and tides is presented. The amplitudes of the mean winds exhibit a significant amplitude response for the zonal component below 82°km during summer and from November to December between 84 and 95°km at Andenes and CMOR. The semidiurnal tides (SDTs) show a clear 11-year response at all locations, from October to November. © 2019 by ASME.

2013, Mielich, J., Bremer, J.

A new comprehensive data collection by Damboldt and Suessmann (2012a) with monthly foF2 and M(3000)F2 median values is an excellent basis for the derivation of long-term trends in the ionospheric F2 region. Ionospheric trends have been derived only for stations with data series of at least 22 years (124 stations with foF2 data and 113 stations with M(3000)F2 data) using a twofold regression analysis depending on solar and geomagnetic activity. Three main results have been derived: Firstly, it could be shown that the solar 10.7 cm radio flux F10.7 is a better index for the description of the solar activity than the relative solar sunspot number R as well as the solar EUV proxy E10.7. Secondly, the global mean foF2 and

2014, Stagl, J., Mayr, E., Koch, H., Hattermann, F.F., Huang, S.

For the management of protected areas knowledge about the water regime plays a very important role, in particular in areas with lakes, wetlands, marches or floodplains. The local hydrological conditions depend widely on temporal and spatial variations of the main components of the hydrologic cycle and physiographic conditions on site. To preserve a favourable conservation status under changing climatic conditions park managers require information about potential impacts of climate change in their area. The following chapter provides an overview of how climate change affects the hydrological regimes in Central and Eastern Europe. The hydrological impacts for the protected areas are area-specific and vary from region to region. Generally, an increase in temperature enhances the moisture holding capacity of the atmosphere and thus, leads to an intensification of the hydrological cycle. Key changes in the hydrological system include alterations in the seasonal distribution, magnitude and duration of precipitation and evapotranspiration. This may lead to changes in the water storage, surface runoff, soil moisture and seasonal snow packs as well as to modifications in the mass balance of Central European glaciers. Partly, water resources management can help to counterbalance effects of climate change on stream flow and water availability.