Kolloquiumsprogramm
Datum: Dienstags von 12:15 bis 13:30 Uhr
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06/10/2020 - Sabine ECKHARDT: "Sources and Concentrations of Black Carbon in the Arctic"
Sabine Eckhardt (Norwegian Institute for Air Research)
"Sources and Concentrations of Black Carbon in the Arctic"Black Carbon (BC) is a light absorbing substance produced by incomplete combustion, during natural or anthropogenic processes. BC emissions from mid and high latitudes are regularly transported into the Arctic, where they can change the snow albedo and interfere with the radiative balance. The Arctic Monitoring and Assessment Program (AMAP) performs every 5 years an investigation of the impact of short lived climate pollutants (to which BC belongs) on the Arctic climate. After a discussion of the most recent assessment, which will be completed this year, we describe sources, measurement techniques and distribution of Arctic BC. A special focus will be the Arctic BC annual concentrations of the last 150 years preserved in icecores. With the Lagrangian Particle transport model FLEXPART we explore the source regions of those impurities and relate them to historic emission inventories.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Hier klicken, um an der Vorlesung teilzunehmen.
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13/10/2020 - Saikiran THARIMENA: "Seismic anatomy of the global oceanic lithosphere - asthenosphere system"
Saikiran Tharimena (University of Vienna, Department for Meteorology und Geophysics)
"Seismic anatomy of the global oceanic lithosphere - asthenosphere system"The concept of the lithosphere asthenosphere system is well defined as the rheological boundary between the rigid lithosphere above and the weaker asthenosphere below. However, its nature remains enigmatic as tight constraints on observables that could distinguish the defining mechanism, such as the depth and seismic velocity gradient at the base of the tectonic plate, the lithosphere asthenosphere boundary (LAB), have proven challenging. Oceanic lithosphere provides an ideal location to test various theories about the nature of the LAB. It is well established that oceanic lithosphere cools, thickens, and subsides as it ages according to conductive cooling models. Yet, this simple realization fails to explain various observations, for example, lower than predicted subsidence of old oceanic lithosphere.
Although previous studies use seismic surface and body waves to image oceanic lithospheric discontinuities, directly connecting them to the LAB have proven challenging. A comprehensive and systematic high-resolution imaging of the lithospheric discontinuities can help constrain the nature of the LAB, which is essential for a better understanding of the formation and evolution of oceanic lithosphere, and the driving forces of plate tectonics and mantle convection.
This talk focuses on comprehensively imaging the LAB beneath oceans at different length scales, with focus on the Pacific Ocean using SS precursors, and on a regional scale at the equatorial mid-Atlantic ridge using receiver functions.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: UZAII, Althanstraße 14, 1090 Wien, im Raum 2B201
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20/10/2020 - Georg MAYR: "Data-driven weather forecasting that includes the end-user"
Georg Mayr (Universität Innsbruck, Department of Atmospheric and Cryospheric Sciences)
"Data-driven weather forecasting that includes the end-user"Weather forecasts ultimately serve to resolve the uncertainty about the future for end-users. Forecasts fulfilling the following wish list might achieve that goal. Information contained in data is conceptually what resolves uncertainty. Ideally, data will come from past, present and future and from all available relevant and information-carrying sources and platforms such as measurements, NWP (re-) forecasts, other field-specific models, statistical models, day-of-year, time-of-day, ... .
Since the full distribution of a forecast variable contains most information the aim is to produce probabilistic forecasts. These must fulfill two conditions: they must be calibrated so that their distribution is indistinguishable from what the atmosphere produces, and they must be sharp so that the distribution of individual forecasts is as narrow as possible. And ultimately, the forecast variable must contain the information that is relevant and useful for the end-user. The talk will flesh out this wish list and give examples how it can be fulfilled.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: UZAII, Althanstraße 14, 1090 Wien, im Raum 2B201
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03/11/2020 - Rona THOMPSON: "Using FLEXPART to estimate greenhouse gas sources and sinks"
Rona Thompson (Norwegian Institute for Air Research)
"Using FLEXPART to estimate greenhouse gas sources and sinks"An important aspect of mitigating greenhouse gas emissions, is to have accurate and up-to-date estimates of what the actual emissions are.
Greenhouse gas fluxes can be estimated independently of emission inventories using observations of atmospheric concentrations and a model of atmospheric tracer transport - the so-called "atmospheric inversion" approach. The basic principles of atmospheric inversion will be presented along with a comprehensive example of the application of the FLEXINVERT inversion framework to estimating fluxes of methane in the high northern latitudes. In addition, an overview of other current applications of FLEXINVERT will be given.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: nur online
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10/11/2020 - Yvonne RUCKSTUHL: "Addressing model error by estimating model parameters with ensemble data assimilation"
Yvonne Ruckstuhl (Ludwig-Maximilians-Universität München, Meteorologisches Institut)
"Addressing model error by estimating model parameters with ensemble data assimilation"The feasibility of addressing model error by perturbing and estimating uncertain static model parameters using an Ensemble Kalman Filter (EnKF) is investigated. In particular the augmented state approach is used, where parameters are updated by observations via their correlation with observed state variables. Results show that in a nearly-operational convection-permitting configuration the prediction of clouds and precipitation with the COSMO-DE model is improved if the two dimensional roughness length parameter is estimated with the augmented state approach. In addition, the short comings of the EnKF are discussed and suitable modifications of the EnKF are presented.
Uhrzeit: 12:15 Uhr bis 13:30 Uhr
Ort: Nur online
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17/11/2020 - Roland POTTHAST: "Online versus 4D Parameter Estimation for NWP - Equivalences and Differences"
Roland Potthast (Deutscher Wetterdienst)
"Online versus 4D Parameter Estimation for NWP - Equivalences and Differences"
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: nur online
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24/11/2020 - Ulrike ROMATSCHKE: "NCAR radar and lidar data from field campaigns"
Ulrike Romatschke (Earth Obserbing Laboratory, NCAR)
"NCAR radar and lidar data from field campaigns"The mission of the Earth Observing Laboratory (EOL) at the National Center for Atmospheric Research (NCAR) is “To develop and deploy observing facilities and provide expertise and data services needed to advance scientific understanding of the Earth System.” EOL deploys observing facilities such as surface weather stations, sounding systems, remote sensing instruments, dropsondes, and facilities aboard two NSF research aircraft, at observational field campaigns for researchers from universities, government agencies, and in support of education. The laboratory serves as a primary resource in the areas of technology of atmospheric measurements and observations, data services, and best practices in field campaign organization and conduct.
As one of five EOL facilities, the Remote Sensing Facility (RSF) deploys two lidar and two radar systems at field campaigns all over the world. Five units of the newly developed MicroPulse DIAL (MPD) fill the need for height-resolved lower troposphere water vapor and temperature measurements. The ground based S-PolKa radar, an advanced, dual-polarized, dual-wavelength Doppler weather radar, has served the scientific community in over 20 field campaigns since 1996. It is the only S-band transportable radar worldwide, which is available to the general scientific community, and is capable of looking into the core of deep convection. Two airborne instruments, the High Spectral Resolution Lidar (HSRL) and the HIAPER Cloud Radar (HCR) are deployed separately or together on the NSF/NCAR Gulfstream V aircraft. Several scientific products are currently being developed for these two instruments such as melting layer altitude, cloud classification, particle ID, or cloud liquid water content.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: nur online
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01/12/2020 - Domenico CIMINI: "Profiling the atmospheric boundary layer at European scale: Prospects and challenges"
Domenico Cimini (National Research Council of Italy, Institute of Methodologies for Environmental Analysis)
"Profiling the atmospheric boundary layer at European scale: Prospects and challenges"The atmospheric boundary layer (ABL) is the layer closest to the Earth's surface within which most human activities take place. The vertical profile of atmospheric thermodynamic parameters in the ABL impact weather, air quality, and climate. Surface sensor networks and satellite observations do not provide sufficient information on the high temporal variability and strong vertical gradients experienced in the ABL. Despite its importance, the ABL continues to be the most under-sampled part of the atmosphere. This observational gap currently hampers our ability to improve weather forecasts, air quality prediction, and climate model parameterization.
However, this gap is mainly due to the lack of networking and coordination. In fact, state-of-the-art ground-based remote sensing instruments able to provide ABL profiles (such as those of temperature, humidity, wind, aerosol, cloud) are currently deployed at numerous sites in Europe, but the harmonization of data and procedures is missing, limiting the effective use and societal benefits of the existing ABL profiling data. This paper introduces PROBE (http://probe-cost.eu/), a new European initiative funded by COST (www.cost.eu), aiming to contribute to filling the ABL observational gap, bridging user needs and the science and technology expertise residing in industry and academia. Here, we describe PROBE’s challenges, objectives, and implementation plan. Preliminary results are presented, including studies on regional NWP impact and network configuration, which will develop among others during the four-year duration (2019-2023).
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: nur online.
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15/12/2020 - George CRAIG: "Forecast probabilities from very large ensembles"
George Craig (Ludwig-Maximilians-Universität München, Meteorologisches Institut)
"Forecast probabilities from very large ensembles"Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: UZAII, Althanstraße 14, 1090 Wien, im Raum 2B201
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19/01/2021 - Florian MEIER: "Challenges in NWP-based nowcasting with a limited area model"
Florian Meier (ZAMG, Wien)
"Challenges in NWP-based nowcasting with a limited area model"Since autumn 2019 a limited area numerical weather prediction (NWP) based nowcasting system has been run operationally at ZAMG. The system is based on the convection permitting spectral AROME model family developed in international collaboration. The specific challanges to run NWP in nowcasting mode regarding selection of observations and data assimilation, model spin-up in rapid assimilation cycling and work flow will be presented as well as some forecasting results.
Dienstag, 12:15 Uhr bis 13:30 Uhr
Ort: UZAII, Althanstraße 14, 1090 Wien, im Raum 2B201