GAWTEC webinars
Topic outline
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The availability of reliable scientific data to characterize the atmosphere’s chemical composition is crucial for understanding air pollution and climate change, their drivers, and their impacts. Data within and across monitoring networks need to meet specific data quality objectives and compatibility goals to be useful for robust analyses. Thus, observations have to be of known quality, sufficient precision and need to be traceable to common scales. The lecture will present the existing challenges but also the required considerations and procedures in terms of implementation and operation. Particular attention will be given to quality assurance and quality control when operating the observations on a long-term basis.
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Modelling of air masses and impacts of Corona lockdown Trace gas concentrations of, e.g., CO2, as observed at towers or mountain stations, are determined by their air mass history. Modelling the air mass history can answer the question about the representativity of the observations. Using the numerical weather prediction model ICON together with the ART module, we can model the plumes of selected emission areas and relate these to the observations. This way, we model when and where the CO2 emission reductions caused by the Corona lockdown reach a measurable magnitude. Clearly, on short time scales, this is mainly determined by meteorological transport and mixing. On longer time scales, the carbon cycle (especially the exchange with the biosphere) has to be taken into account.
The ultimate aim is to relate measured greenhouse gas concentrations to their emissions, for the purpose of emission reduction verification. Several scientific projects are working on this, international exchange is provided by, e.g., the WMO subsidiary Integrated Global Greenhouse Gas Information System (IG3IS).
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Greenhouse gases are key drivers for climate change. The greenhouse gas concentrations in the atmosphere are defined by their sources and sinks, which vary substantially in space and time. To estimate and control the growth of their emissions, an extensive measuring network is required. The European research infrastructure and network "Integrated Carbon Observation System" (ICOS) https://www.icos-cp.eu/ makes high quality standardised measurements of greenhouse gases. ICOS is a Global Atmosphere Watch (GAW) contributing network.
As part of the German contribution (ICOS-D) to the ICOS Atmosphere network, nine long-term tall tower monitoring stations have been established in Germany to estimate the greenhouse gas fluxes with high spatial and temporal resolution. At each station concentrations of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO) and nitrous oxide (N2O) as well as meteorological parameters are continuously observed at 3 to 5 measurement heights (up to 341 m a.g.l.). The data are used for inverse modelling to provide a spatially resolved picture of emissions (spatial resolution of 0.1 ° x 0.1 °). ICOS-D follows the strong guidelines and quality requirements of ICOS-EU and GAW to assure high quality measurements. The Webinar will cover the German tall tower network, the station set up and the application of ICOS QA/QC procedures. Selected results from the measurements will also be shown.
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UREC4A, initially a Caribbean-French-German, partnership field study was supported by the World Climate Research Programme Grand Science Challenge on Clouds, Circulation and Climate Sensitivity. This international enterprise’s base of operations was in Barbados from 20 January- 20 February 2020.
This study concentrated on quantifying how cloudiness in shallow cumulus layers responds to changes in the large-scale environment and how shallow clouds affect radiant energy transfer for different forms of convective organization. Cloud and atmospheric properties, and numerical simulations of shallow cumulus cloud regimes by large-eddy simulation, weather prediction and climate models were retrieved.
To ensure the objectives were met, surface based measurements from the Barbados Cloud Observatory; airborne measurements from the German HALO (High Altitude Long Range) and French ATR research aircraft, and ship based measurements from the German R/V Meteor were supplemented by a large number of additional platforms. EUREC4A-UK (a UK project),the British Antarctic Survey’s Twin Otter (TO for short) and ground based facilities for aerosol measurements to advance cloud physics studies; EUREC4A-OA (the Ocean-Atmosphere component of EUREC4A) secured the service of two additional research vessels (the French R/V L’Atalante and the German R/V Maria Sybilla Merian) and various autonomous observing platforms to study ocean processes. The ATOMIC1 (a parallel running US research project) brought an additional research vessel, the NOAA R/V Ronald H. Brown, assorted autonomous systems, and the NOAAWP-3D Orion coined as Ms Piggy, to help augment studies of air-sea and aerosol-cloud interactions. Further national initiatives funded a large-scale sounding array, the installation of a scanning precipitation radar, the deployment of ship-borne CloudKites, a network of water stable iso-topologue measurements, as well as a rich assortment of asynchronous aerial and seagoing systems, among them fixed-wing aircraft, quad copters, drifters, buoys, gliders, and sail-drones.
There was operational support from the Caribbean Institute for Meteorology and Hydrology (CIMH) personnel and the region’s operational forecasters. CIMH was instrumental in ensuring that all educational outreach projects envisioned by the planning team occurred. Some of the activities such as DLR PoldiRad (A scanning C-band research radar) collection of convective data continued to be staffed by local personnel, even after the field study ended. Regional scientists who took part in the event as project forecasters and observing scientists on the various platforms, initiated collaborations with international scientists on various concepts/topics. The current and potential findings from EUREC4A are being explored and promise to substantially advance understanding of the clouds in the trade-winds.
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Reactive gases in the atmosphere encompass a highly diverse group of chemicals with different properties and characteristics, including nitrogen oxides (NOx), volatile organic compounds (VOCs) and surface ozone (O3). These gases are chemically active and therefore present in only trace amounts in the atmosphere, with large variations in their concentration across space and time. The trace gases and their reaction products, which are formed through reaction with oxidants in the atmosphere, influence air pollution, climate and ecosystems. This talk gives an overview of the different sources and chemistry of reactive gases and discusses these important impacts.
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Surface ozone is both a greenhouse gas and a secondary air pollutant which is harmful to human health and ecosystem productivity. It is not directly emitted but formed by chemical reactions of so-called ozone precursors (mainly nitrogen oxides, carbon monoxide, methane and non-methane volatile organic compounds) in the presence of sunlight. Since surface ozone is a regulated air pollutant, accurate and reproducible measurements are required.
This webinar gives an overview of ozone measurements in the Global Atmosphere Watch (GAW) programme and covers the following topics- History of ozone measurement techniques
- Current measurement techniques for surface ozone
- Measurement setup
- Station settings and requirements
- Traceability, calibration and quality assurance of surface ozone measurements
- Overview of standards and guidance documents
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Carbon monoxide (CO) is a central molecule in atmospheric composition monitoring and research. Mole fractions in the troposphere range from less than 100 ppb in remote areas to a few ppm in urban environments. Major sources are fossil fuel combustion, biomass burning and oxidation of methane and nonmethane hydrocarbons. Despite being a reactive gas with an atmospheric lifetime of a few days to months, CO is also considered as an indirect greenhouse gas as it interacts in the oxidative chain reactions and, consequently, also influences the lifetime of long-lived greenhouse gases such as methane. Thus, carbon monoxide plays an important role in atmospheric chemistry, the carbon cycle, and the Earth's radiative budget.
The Global Atmosphere Watch Programme (GAW) of the World Meteorological Organization lists CO as one of its recommended measurement variables. Several fundamentally different measurement techniques exist for CO observations. The lecture will give a comprehensive overview of the most common techniques and related quality assurance / quality control recommendations.
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Volatile Organic Compounds (VOCs) occur in the atmosphere at low to sub parts per billion mole fractions. This poses enormous challenges for their measurement and quantification. A variety of measurement approaches building on different principles have been developed that allow for the selective monitoring of VOCs at these low concentrations. This presentation will provide an overview of VOCs measurement approaches, their technical realization for monitoring methods, and examples of common applications.
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Nitrogen oxides (NOx), the sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2), play a central role in atmospheric chemistry. Nitrogen oxides form in the atmosphere during lightning strikes or during microbial processes in soils. The main part, however, is anthropogenic during combustion processes, with traffic being the main cause of nitrogen oxides. Although NO2 concentrations are decreasing, it is a still hazardous air pollutant in many parts of the world.
Consequently, there is a need to monitor nitrogen oxides. This is acknowledged in the World Meteorological Organization Global Atmospheric Watch Program.
In this lecture I will give an overview on the diurnal and seasonal cycles of nitrogen oxides an on the factors the govern the observed mixing ratios. In the second part measurements techniques of nitrogen oxides will be introduced.
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Anthropogenic emissions, climate change and mitigation strategies alter the composition of trace gases with impact on air quality and climate. Since 1995, the Hohenpeissenberg meteorological observatory operated by the German Meteorological Service (DWD) performs observations of atmospheric key species in Southern Germany within the Global Atmosphere Watch (GAW) program. The atmospheric composition, characteristic for central Europe, has been continuously monitored including reactive gases such as in-situ ozone, nitrogen oxides, carbon monoxide, anthropogenic and biogenic VOCs and total OH reactivity. This presentation will give an overview of the reactive trace gas measurement programme, their observations and interactions and the resulting change of the atmospheric composition at Hohenpeissenberg.
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The EBAS atmospheric database, originally designed for the European Monitoring and Evaluation Programme (EMEP), archives today data on atmospheric composition from ground stations around the globe. GAW-WDCA and GAW-WDCRG are co-operating frameworks, and this presentation will provide information on how to submit data to EBAS and the benefits of storing the data in EBAS.
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