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- ItemTrend detection in river flow indices in Poland(Heidelberg : Springer, 2018) Piniewski, Mikołaj; Marcinkowski, Paweł; Kundzewicz, Zbigniew W.The issue of trend detection in long time series of river flow records is of vast theoretical interest and considerable practical relevance. Water management is based on the assumption of stationarity; hence, it is crucial to check whether taking this assumption is justified. The objective of this study is to analyse long-term trends in selected river flow indices in small- and medium-sized catchments with relatively unmodified flow regime (semi-natural catchments) in Poland. The examined indices describe annual and seasonal average conditions as well as annual extreme conditions—low and high flows. The special focus is on the spatial analysis of trends, carried out on a comprehensive, representative data set of flow gauges. The present paper is timely, as no spatially comprehensive studies (i.e. covering the entire Poland or its large parts) on trend detection in time series of river flow have been done in the recent 15 years or so. The results suggest that there is a strong random component in the river flow process, the changes are weak and the spatial pattern is complex. Yet, the results of trend detection in different indices of river flow in Poland show that there exists a spatial divide that seems to hold quite generally for various indices (annual, seasonal, as well as low and high flow). Decreases of river flow dominate in the northern part of the country and increases usually in the southern part. Stations in the central part show mostly ‘no trend’ results. However, the spatial gradient is apparent only for the data for the period 1981–2016 rather than for 1956–2016. It seems also that the magnitude of increases of river flow is generally lower than that of decreases.
- ItemChanges of snow cover in Poland(Heidelberg : Springer, 2017) Szwed, Małgorzata; Pin´skwar, Iwona; Kundzewicz, Zbigniew W.; Graczyk, Dariusz; Mezghani, AbdelkaderThe present paper examines variability of characteristics of snow cover (snow cover depth, number of days with snow cover and dates of beginning and end of snow cover) in Poland. The study makes use of a set of 43 long time series of observation records from the stations in Poland, from 1952 to 2013. To describe temporal changes in snow cover characteristics, the intervals of 1952–1990 and of 1991–2013 are compared and trends in analysed data are sought (e.g., using the Mann–Kendall test). Observed behaviour of time series of snow-related variables is complex and not easy to interpret, for instance because of the location of the research area in the zone of transitional moderate climate, where strong variability of climate events is one of the main attributes. A statistical link between the North Atlantic Oscillation (NAO) index and the snow cover depth, as well as the number of snow cover days is found.
- ItemWhat can we learn from the projections of changes of flow patterns? Results from Polish case studies(Heidelberg : Springer, 2017) Piniewski, Mikołaj; Meresa, Hadush Kidane; Romanowicz, Renata; Osuch, Marzena; Szczes´niak, Mateusz; Kardel, Ignacy; Okruszko, Tomasz; Mezghani, Abdelkader; Kundzewicz, Zbigniew W.River flow projections for two future time horizons and RCP 8.5 scenario, generated by two projects (CHASE-PL and CHIHE) in the Polish-Norwegian Research Programme, were compared. The projects employed different hydrological models over different spatial domains. The semi-distributed, process-based, SWAT model was used in the CHASE-PL project for the entire Vistula and Odra basins area, whilst the lumped, conceptual, HBV model was used in the CHIHE project for eight Polish catchments, for which the comparison study was made. Climate projections in both studies originated from the common EURO-CORDEX dataset, but they were different, e.g. due to different bias correction approaches. Increases in mean annual and seasonal flows were projected in both studies, yet the magnitudes of changes were largely different, in particular for the lowland catchments in the far future. The HBV-based increases were significantly higher in the latter case than the SWAT-based increases in all seasons except winter. Uncertainty in projections is high and creates a problem for practitioners.
- ItemClimatologies and long-term changes in mesospheric wind and wave measurements based on radar observations at high and mid latitudes(Göttingen : Copernicus GmbH, 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.
- ItemHigh-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum(Katlenburg, Lindau : Copernicus, 2018-4-3) Li, Qiang; Rapp, Markus; Stober, Gunter; Latteck, RalphThe 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.
- ItemAssessment of climate change and associated impact on selected sectors in Poland(Warsaw : De Gruyter Open, 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 ErikThe 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.
- ItemAerosol Particle and Black Carbon Emission Factors of Vehicular Fleet in Manila, Philippines(Basel, Switzerland : MDPI AG, 2019) Madueño, Leizel; Kecorius, Simonas; Birmili, Wolfram; Müller, Thomas; Simpas, James; Vallar, Edgar; Galvez, Maria Cecilia; Cayetano, Mylene; Wiedensohler, AlfredPoor air quality has been identified as one of the main risks to human health, especially in developing regions, where the information on physical chemical properties of air pollutants is lacking. To bridge this gap, we conducted an intensive measurement campaign in Manila, Philippines to determine the emission factors (EFs) of particle number (PN) and equivalent black carbon (BC). The focus was on public utility jeepneys (PUJ), equipped with old technology diesel engines, widely used for public transportation. The EFs were determined by aerosol physical measurements, fleet information, and modeled dilution using the Operational Street Pollution Model (OSPM). The results show that average vehicle EFs of PN and BC in Manila is up to two orders of magnitude higher than European emission standards. Furthermore, a PUJ emits up to seven times more than a light-duty vehicles (LDVs) and contribute to more than 60% of BC emission in Manila. Unfortunately, traffic restrictions for heavy-duty vehicles do not apply to PUJs. The results presented in this work provide a framework to help support targeted traffic interventions to improve urban air quality not only in Manila, but also in other countries with a similar fleet composed of old-technology vehicles. © 2019 by the authors.
- ItemAtomic oxygen number densities in the mesosphere–lower thermosphere region measured by solid electrolyte sensors onWADIS-2(Katlenburg-Lindau : Copernicus, 2019) Eberhart, Martin; Löhle, Stefan; Strelnikov, Boris; Hedin, Jonas; Khaplanov, Mikhail; Fasoulas, Stefanos; Gumbel, Jörg; Lübken, Franz-Josef; Rapp, MarkusAbsolute 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. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
- ItemDust mass, cloud condensation nuclei, and ice-nucleating particle profiling with polarization lidar: Updated POLIPHON conversion factors from global AERONET analysis(Göttingen : Copernicus GmbH, 2019) Ansmann, A.; Mamouri, R.-E.; Hofer, J.; Baars, H.; Althausen, D.; Abdullaev, S.F.The POLIPHON (Polarization Lidar Photometer Networking) method permits the retrieval of particle number, surface area, and volume concentration for dust and non-dust aerosol components. The obtained microphysical properties are used to estimate height profiles of particle mass, cloud condensation nucleus (CCN) and ice-nucleating particle (INP) concentrations. The conversion of aerosol-type-dependent particle extinction coefficients, derived from polarization lidar observations, into the aerosol microphysical properties (number, surface area, volume) forms the central part of the POLIPHON computations. The conversion parameters are determined from Aerosol Robotic Network (AERONET) aerosol climatologies of optical and microphysical properties. In this article, we focus on the dust-related POLIPHON retrieval products and present an extended set of dust conversion factors considering all relevant deserts around the globe. We apply the new conversion factor set to a dust measurement with polarization lidar in Dushanbe, Tajikistan, in central Asia. Strong aerosol layering was observed with mineral dust advected from Kazakhstan (0-2km height), Iran (2-5km), the Arabian peninsula (5-7km), and the Sahara (8-10km). POLIPHON results obtained with different sets of conversion parameters were contrasted in this central Asian case study and permitted an estimation of the conversion uncertainties.
- ItemA new method of inferring the size, number density, and charge of mesospheric dust from its in situ collection by the DUSTY probe(Katlenburg-Lindau : Copernicus, 2019) Havnes, Ove; Antonsen, Tarjei; Baumgarten, Gerd; Hartquist, Thomas W.; Biebricher, Alexander; Fredriksen, Åshild; Friedrich, Martin; Hedin, JonasWe present a new method of analyzing measurements of mesospheric dust made with DUSTY rocket-borne Faraday cup probes. It can yield the variation in fundamental dust parameters through a mesospheric cloud with an altitude resolution down to 10 cm or less if plasma probes give the plasma density variations with similar height resolution. A DUSTY probe was the first probe that unambiguously detected charged dust and aerosol particles in the Earth's mesosphere. DUSTY excluded the ambient plasma by various biased grids, which however allowed dust particles with radii above a few nanometers to enter, and it measured the flux of charged dust particles. The flux measurements directly yielded the total ambient dust charge density. We extend the analysis of DUSTY data by using the impact currents on its main grid and the bottom plate as before, together with a dust charging model and a secondary charge production model, to allow the determination of fundamental parameters, such as dust radius, charge number, and total dust density. We demonstrate the utility of the new analysis technique by considering observations made with the DUSTY probes during the MAXIDUSTY rocket campaign in June-July 2016 and comparing the results with those of other instruments (lidar and photometer) also used in the campaign. In the present version we have used monodisperse dust size distributions.© Author(s) 2019.