Für Wetter und Klima – Maritim-Meteorologische Observationen beim DWD

<p>Die Erfassung und Überwachung des Wetters und des Klimas auf den Weltmeeren hat eine lange Tradition beim Deutschen Wetterdienst (DWD) und seinen Vorgängerorganisationen in Hamburg. Seit dem 19. Jahrhundert werden auf Schiffen systematisch meteorologische und ozeanographische Informationen gesammelt, die ein detailliertes Verständnis des maritimen Wetters und des Klimas ermöglichen. Bis heute sind die meteorologischen Schiffsbeobachtungen eine wichtige Datenquelle für die Wettervorhersage und die Klimaüberwachung.</p> <p>Der Deutsche Wetterdienst betreibt ein großes meteorologisches maritimes Messnetz, welches mehr als 500 Schiffe umfasst, die regelmäßig Wetterbeobachtungen auf allen Weltmeeren durchführen. Diese Schiffe beteiligen sich am internationalen <em>Voluntary Observing Ship (VOS) Scheme</em> und ihre Beobachtungen werden in Echtzeit über das globale Telekommunikationssystem (GTS) der WMO verbreitet. Dabei wird eine zunehmende Anzahl von Beobachtungen von automatischen Wetterstationen an Bord von Schiffen geliefert.</p> <p>Neben der Nutzung für die operationelle Wettervorhersage sind die maritim-meteorologischen Observationen ein wichtiger Beitrag zu klimatologischen Archiven wie der In-situ Datenbank des maritimen Klimadatenzentrums des DWD. Diese Datenbank besteht aus qualitätskontrollierten Daten aus Echtzeit- und <em>delayed mode</em> Datenströmen, sowie aus einer großen Menge historischer Daten. Der Datenbestand wächst kontinuierlich durch aktuelle operationelle Dateneingänge, aber auch durch die Digitalisierung alter meteorologischer Schiffsjournale und reicht von heute bis weit zurück in das 19 Jahrhundert. Im Rahmen des internationalen Datenaustauschs über die WMO / IOC <em>VOS Global Data Assembly Centres</em> (GDACs) werden die maritimen Klimadaten regelmäßig in den <em>International Comprehensive Ocean-Atmosphere Data Set</em> (ICOADS) integriert. Des Weiteren werden die Daten für eine Vielzahl von Klimaanwendungen verwendet, z.B. als Input für Reanalysen, für die operationelle Klimaüberwachung, klimatologische Analysen und Datenprodukte, sowie für die Kalibrierung von Satellitenbeobachtungen.</p>

ICON-waves: towards an atmosphere-waves coupled

<p>Wind-driven ocean gravity surface waves affect basic physical processes such as heat, momentum, and mass exchange between the ocean and the atmosphere. Wind wave energy generates additional turbulence, modifies ocean currents, and controls the state of the sea surface. As of now, DWD's operational weather forecast system ICON-NWP does not explicitly account for ocean surface waves. Wave effects, for example, the effect on sea surface roughness, are represented by parameterisations based on local wind speed. However, the physics of the ocean-atmosphere interaction is more complex, and therefore methods of wave-spectrum-based coupling of atmosphere and ocean are necessary and have the potential for improving both weather and wave forecasts. To this end, in the framework of the Innovation Programme for Applied Research and Developments (IAFE) funded by the DWD, a new coupled ICON-NWP-waves system is currently under development. This project aims at using ICON's dynamical core and the wave spectrum physics from the wave model WAM, and will combine both into the new ICON-waves model. A parameterisation of sea surface roughness based on the wave spectrum will provide a two-way coupling mechanism at the ocean-atmosphere interface. The concept of ICON-waves, the current status of development as well as some preliminary results will be presented.<span class="Apple-converted-space"> </span></p>

Global warming pattern formation: the role of ocean heat uptake

This study investigates the formation mechanism of ocean surface warming pattern in response to a doubling CO2 with a focus on the role of ocean heat uptake (or ocean surface heat flux change, ΔQnet). We demonstrate that the transient patterns of surface warming and rainfall change simulated by the dynamic ocean-atmosphere coupled model (DOM) can be reproduced by the equilibrium solutions of the slab ocean-atmosphere coupled model (SOM) simulations when forced with the DOM ΔQnet distribution. The SOM is then used as a diagnostic, inverse modeling tool to decompose the CO2-induced thermodynamic warming effect and the ΔQnet (ocean heat uptake)-induced cooling effect. As ΔQnet is largely positive (i.e., downward into the ocean) in the subpolar oceans and weakly negative at the equator, its cooling effect is strongly polar amplified and opposes the CO2 warming, reducing the net warming response especially over Antarctica. For the same reason, the ΔQnet-induced cooling effect contributes significantly to the equatorially enhanced warming in all three ocean basins, while the CO2 warming effect plays a role in the equatorial warming of the eastern Pacific. The spatially varying component of ΔQnet, although globally averaged to zero, can effectively rectify and lead to decreased global mean surface temperature of a comparable magnitude as the global mean ΔQnet effect under transient climate change. Our study highlights the importance of air-sea interaction in the surface warming pattern formation and the key role of ocean heat uptake pattern.

DENDROCHRONOLOGY AND RADIOCARBON DATING

ABSTRACT Both dendrochronology and radiocarbon (14C) dating have their roots back in the early to mid-1900s. Although they were independently developed, they began to intertwine in the 1950s when the founder of dendrochronology, A. E. Douglass, provided dated wood samples for Willard Libby to test his emerging 14C methods. Since this early connection, absolutely dated tree-rings have been key to calibration of the Holocene portion of the 14C timescale. In turn, 14C dating of non-calendar-dated tree-rings has served to place those samples more precisely in time, advance development of long tree-ring chronologies, and bring higher resolution to earlier portions of the 14C calibration curve. Together these methods continue to shape and improve chronological frameworks across the globe, answering questions in archaeology, history, paleoclimatology, geochronology, and ocean, atmosphere, and solar sciences.

US SOLAS Science Report

The Surface Ocean – Lower Atmosphere Study (SOLAS) (http://www.solas-int.org/) is an international research initiative focused on understanding the key biogeochemical-physical interactions and feedbacks between the ocean and atmosphere that are critical elements of climate and global biogeochemical cycles. Following the release of the SOLAS Decadal Science Plan (2015-2025) (Brévière et al., 2016), the Ocean-Atmosphere Interaction Committee (OAIC) was formed as a subcommittee of the Ocean Carbon and Biogeochemistry (OCB) Scientific Steering Committee to coordinate US SOLAS efforts and activities, facilitate interactions among atmospheric and ocean scientists, and strengthen US contributions to international SOLAS. In October 2019, with support from OCB, the OAIC convened an open community workshop, Ocean-Atmosphere Interactions: Scoping directions for new research with the goal of fostering new collaborations and identifying knowledge gaps and high-priority science questions to formulate a US SOLAS Science Plan. Based on presentations and discussions at the workshop, the OAIC and workshop participants have developed this US SOLAS Science Plan. The first part of the workshop and this Science Plan were purposefully designed around the five themes of the SOLAS Decadal Science Plan (2015-2025) (Brévière et al., 2016) to provide a common set of research priorities and ensure a more cohesive US contribution to international SOLAS.