483 research outputs found
OCEANET-ATMOSPHERE low level stratus clouds during PS106
No full textThe dataset contains daily nc-files of the observed low level stratus clouds during Polarstern cruise PS106. These clouds were present below the lowest cloud radar range gate (155 m above the instrument) and hence not represented in the related Cloudnet data set.
The low level stratus cloud were detected using the SNR of the OCEANET multiwavelength Raman and polarization lidar PollyXT (Engelmann et al., 2016 doi:10.5194/amt-9-1767-2016 ; Baars et al., 2017 doi:10.5194/amt-10-3175-2017 )
OCEANET-ATMOSPHERE PollyXT measurements during POLARSTERN cruise PS106
No full textThe dataset contains daily nc-files of the attenuated backscatter coefficient and volume depolarization from the OCEANET multiwavelength Raman and polarization lidar PollyXT (Engelmann et al., 2016, doi:10.5194/amt-9-1767-2016; Baars et al., 2017, doi:10.5194/amt-10-3175-2017) during Polarstern cruise PS106.
The data is calibrated within the Cloudnet (Illingworth, 2007 doi:10.1175/BAMS-88-6-883) processing scheme
Low-level stratus mask from Polarstern during MOSAiC
No full textDaily files of low-level stratus (LLS) for the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition (Shupe et al., 2022). The LLS was detected following Griesche et al. (2020) based on near-range data from PollyXT (Engelmann et al., 2016) to extend the Cloudnet cloud properties derived for MOSAiC (Engelmann et al. 2023; doi:10.60656/59216bca3a304156) into the bild zone of the cloud radar (i.e. below 180 m altitude). The applied method was updated to the use of the attenuated backscatter (att bsc) instead of the signal-to-noise ratio to reduce the influence of changes in the system constant on the LLS detection. An LLS was identified when the att bsc exceeded a threshold of 4e-06 sr-1 m-1 below 180 m. Data issues caused by external drivers are documented in a separate issue tracking file (Griesche & Seifert, 2023; doi:10.5281/zenodo.7310858). Flagged data must be handled with care and should be excluded from statistical analyses. Issues tracking flags are identified by tethered balloon operation periods and experienced-eye observations of MOSAiC staff
Optical aerosol profiles from the Raman Lidar Polly-XT during MOSAiC
No full textDuring the one-year MOSAiC expedition the multiwavelength polarization Raman lidar Polly (POrtabLe Lidar sYstem) (Engelmann et al., 2016, 2021) was continuously operated aboard Polarstern. Automated measurements of aerosol and cloud profiles up to stratospheric heights were collected from 26 September 2019 to 2 October 2020. The Polly instrument is mounted inside the OCEANET-Atmosphere container of the Leibniz Institute for Tropospheric Research (TROPOS). Data are manually analyzed height profiles of particle backscatter coefficient, particle extinction coefficient, particle linear depolarization ratio, extinction-to-backscatter ratio, and Anstrom exponents at 355 nm, 532 nm, and 1064 nm wavelengths
Doppler lidar datasets of UDINE measurement campaign at TROPOS Leipzig, Germany
No full textThe Doppler lidar dataset of the Up- and Downdraft in Drop and Ice Nucleation Experiment (UDINE, 2010-2013) is published. This dataset is part of the publication Bühl et al., "Impact of vertical air motions on ice formation rate in mixed-phase cloud layers", NPJ Climate and Atmospheric Science, 2019.
Time-height resolved measurements of mean vertical Doppler velocity of aerosol and cloud particles over the measurement site. Most data is recorded in vertical stare with 2s measurement time. Files are in NetCDF-format and contain the following variables:
amp(time,height): The signal strength (SNR) recorded by the data acquisition.
data(time,height): The first moment of the main peak in the Doppler spectrum
heightresolution: The resolution of the data acquisition in nanoseconds
measurement_time(time,datetime): Time of recording in human readable format [YYYYMMDD,hhmmss]
scanposition(time,scanposition): Two element array with position of the scanner in [azimuth,off-zenith-angle]
shots(time): The number of shots used for averaging. Spectra are averaged at a rate of 750 shots/s so this variables indicates if the system has functioned nominally.</p
Letter from [author unknown] to John Muir, 1884 Apr 2
No full textDr. George Engelmann Born at Frankfurt on the Main, February 2nd, 1809 DIED, In the midst of his scientific labors at his more in St. Louis, on Monday, February 4th, 1884, in the seventy-fifth year of his age 3003 Locust Street, St. Louis March 10th, 1884https://scholarlycommons.pacific.edu/jmcl/44166/thumbnail.jp
Comparison of measured and forecasted water-vapor profilesduring COPS 2007
No full textMeasurements with the multiwavelength Raman pola-rization lidar BERTHA (Backscatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) have been performed during COPS (Convective Orographi-cally induced Precipitation Study) in the Black Forest, Germany, from June to August 2007.
Profiles of the water-vapor mixing ratio from BERTHA are compared with data from radiosonde and an air-borne DIAL (Differential Absorption Lidar) LEANDRE2 onboard the French Safire Falcon). The data of the two lidar systems are in better agreement (average difference of -0.03 g kg-1) than the comparisons of BERTHA and the radiosonde data (average difference smaller than 0.5 g kg-1). The discrepancy between lidar and radiosonde data is attributed to the drift of the radiosonde during its ascent.
Raman lidar data are compared with short-range out-puts of the COSMO-DE model (Consortium for small-scale modeling; www.cosmo-model.org) of the Ger-man Weather Service. It is shown that the short-range forecast of water-vapor mixing ratio within the residual layer yields values that are on average 7.9% smaller than the measurement. In the free troposphere pre-dicted values are 9.7% smaller than the measurement
Fächerübergreifende Naturwissenschaften in der Lehrerfortbildung: eine Didaktische Rekonstruktion
No full textDie vorliegende Arbeit stellt die fachdidaktische Entwicklung eines Fortbildungskonzeptes vor, das Lehrkräfte fachlich wie fachdidaktisch auf das Unterrichten fächer-übergreifender Naturwissenschaften vorbereitet. Das Kernelement des Vorhabens ist dabei die empirisch begleitete inhaltliche Strukturierung der Fortbildung durch eine fachliche Analyse und anschließende Konstruktion von Fortbildungselementen anhand ausgewählter interdisziplinärer Kontexte. Diese werden von einer Inter-viewstudie und einem begleitenden Evaluationskonzept umrahmt und betten sich in das Modell der Didaktischen Rekonstruktion ein. Kontextorientierung, Basiskonzepte, naturwissenschaftliche Denk- und Arbeitsweisen sowie Experimente wurden als re-levante Konstruktionskriterien abgeleitet. Die entwickelte Fortbildung charakterisiert sich durch eine fachliche Fundierung physikalischer, chemischer und biologischer Grundlagen, die in exemplarische Kontexte gesetzt sind und sich neben einem fä-cherübergreifenden Fokus auch durch einen erhöhten Forschungsbezug im Sinne moderner Inhalte auszeichnen. Die Herausforderung von Fortbildungen für fächer-übergreifende Naturwissenschaften liegt dabei stets in dem Wechselspiel aus einer fachlichen Ausbildung der Lehrkräfte und der zugehörigen Einbettung in den Unter-richtsalltag. Als fachdidaktische Leitlinie eignen sich dabei Experimente als Grund-lage für die Diskussion unterrichtspraktischer Umsetzungen. Strukturell konnte ein Angebot geschaffen werden, das sich mit den Anforderungen an professionelle Lehrerfortbildungen deckt und als schuljahresbegleitendes Programm angelegt ist. Die Veranstaltungsstruktur ist methodisch durch Vortrag, Praktikum und Reflexion gestaltet. Im Rahmen dieser Arbeit wurden somit u. a. die Themen Bionik, Arzneimit-tel, Regenerative Kraftstoffe, Wasser-Boden-Luft und Kohlenstoffnanomaterialien als Themenhefte mit Sachtexten, Experimentieranleitungen und Lernmaterialien fachdidaktisch rekonstruiert
Ash dieback and hydrology affect tree growth patterns under climate change in European floodplain forests
No full textAbstract Floodplain forests are currently undergoing substantial reorganization processes due to the combined effects of management-induced altered hydrological conditions, climate change and novel invasive pathogens. Nowadays, the ash dieback is one of the most concerning diseases affecting European floodplain forests, causing substantial tree mortality and threatening the loss of the dominant key tree species of the hardwood floodplain forest, Fraxinus excelsior . Understanding how the increased light availability caused by pathogen-driven mortality in combination with altered hydrological conditions and climate change affects growth responses in a diverse forest community is of crucial importance for conservation efforts. Thus, we examined growth of the main tree species in response to ash dieback and how it depended on altered hydrological conditions under novel climatic conditions for the lower and upper canopy in the floodplain forest of Leipzig, Germany. Our study period encompassed the consecutive drought years from 2018 to 2020. We found that tree growth responded mostly positively to increased light availability, but only on moist sites, while tree growth largely declined on dry sites, suggesting that water availability is a critical factor for tree species to be able to benefit from increased light availability due to canopy disturbances caused by ash dieback. This hydrological effect was species-specific in the lower canopy but not in the upper canopy. While, in the lower canopy, some species such as the competitive shade-tolerant but flood-intolerant Acer pseudoplatanus and Acer platanoides benefited from ash dieback on moist sites, others were less affected or suffered disproportionally, indicating that floodplain forests might turn into a novel ecosystem dominated by competitive Acer species, which may have detrimental effects on ecosystem functioning. Our results give hints on floodplain forests of the future and have important implications for conservation measures, suggesting that a substantial revitalization of natural hydrological dynamics is important to maintain a tree composition that resembles the existing one and thus sustain their conservation status
A mosaic of induced and non-induced branches promotes variation in leaf traits, predation and insect herbivore assemblages in canopy trees
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