Lower air volume in valleys than in adjacent plains together with diabatic heating or cooling induces an along-valley temperature and pressure gradient which drives the valley wind. This phenomenon will be quantified for the Mesolcina valley in the Swiss Alps. The method we develop is based on high resolution topography data. From this information the temperature and pressure tendency can be derived for a period with sensible heat flux at the surface. To calculate the wind field, the circulation theorem will be applied. The results of the model runs will be compared to measured data from the field experiment VOTALP (Vertical Ozone Transport in the Alps). In this campaign ground based and airborne instruments collected data of the atmospheric conditions in the valley and the synoptic windfield above.
Basierend auf dem Energiewendeziel der Bundesregierung will sich der Campus Charlottenburg (TU Berlin, UdK Berlin) energetisch als vorbildliche Einrichtung etablieren. Dafür soll der HochschulCampus Berlin-Charlottenburg (HCBC) so saniert werden, dass bereits ab dem Jahr 2023 die Wärmewendeziele 2050 in Teilen demonstriert werden können. Die Basis für die Umsetzung ist das Ergebnis der ersten Phase des Projekts (FKZ: 03ET1354-X). Dieser Masterplan Energie berücksichtigt die Energiebedarfe von Heizung, Kälte und den Hilfsenergien für den Transport von Wärme, Kälte und Luft. Ein Hauptaugenmerk liegt auf der lokalen Gewinnung und Speicherung von Energie, wo günstige Bedingungen für eine anschließende Verschiebung von Wärmeenergieströmen herrschen. Das andere Augenmerk liegt auf der gebäudeweisen energetischen Teilsanierung im Quartiersverbund im Gegensatz zur gebäudeweisen Einhaltung der EnEV. Im Rahmen der 1. Umsetzungsphase sollen in den nächsten 5 Jahren Primärenergieeinsparungen/-substitutionen auf dem gesamten Campus in Höhe von zunächst 40 % zur Basis 2016 bis 2035 das Wärmewendeziel in Höhe von 80 % zur Basis 2008 realisiert werden. Parallel zu den Sanierungsmaßnahmen soll eine Demonstrationsanlage entstehen, in dem die gebäudeübergreifende Nutzung von erneuerbaren Energien und Abwärme über ein Mehrleiter-Wärmenetz gepaart mit Kurz- und Langzeitspeichern getestet und optimiert wird. Aus den Ergebnissen des EnEff: HCBC Projekts sollen Handlungsempfehlungen entwickelt werden, die auf andere Stadtgebiete übertragen werden können.
Clouds are important sources and sinks of diabatic heat, not only in terms of latent heat release but also with respect to absorption of solar radiation as well as absorption and emission of thermal radiation. Additionally, cloud shadows on the ground modify surface heating and thus sensible and latent heat fluxes. Although it has been demonstrated that cloud top cooling may reach values of several 100 K/day and that this may have a strong impact on cloud microphysics and local cloud evolution, it has not been demonstrated that there is actually an effect on weather, larger scale dynamics, and on atmospheric flow. This is even more true for radiative cooling from cloud sides which has been shown to reach values comparable to cloud top cooling but is completely neglected by any (one-dimensional) radiation scheme in current NWP or climate models. Radiation firstly affects the growth of cloud droplets, increasing (in case of thermal cooling) or decreasing (in case of solar heating) the rate by which they dissipate the energy released by latent heat. Secondly, the surrounding air is cooled or heated which directly feeds back on dynamics. The aim of the project is to study the question if realistic, three-dimensional radiative heating rates have an impact on cloud formation, and if there is an impact on atmospheric flow beyond cloud scale. To answer these questions, a reasonably fast but accurate representation of radiative heating rates in clouds will be developed for a cloud scale (EULAG) and an NWP model (COSMO). The project builds upon our previous work on three-dimensional heating and cooling rates and on development of reasonably fast approximations. A parameterization of heating rates depends strongly on the scale. For a cloud-resolving model like EULAG with a 100 m grid size and smaller, different approaches are needed compared to a numerical weather forecast model like COSMO: A cloud-resolving model allows properly resolving the radiation processes, but three-dimensional radiation transport requires interaction between many grid columns in the calculation which is a challenge for parallelization. The resolution of COSMO, on the other hand, requires parameterization of un-resolved cloud edge effects and sub-pixel cloudiness, but would need less interaction between individual grid columns. As a first step, we will study the impact of radiative heating and cooling in clouds on local circulation at cloud scale. For that purpose, an accurate yet fast approximation for 3D solar and thermal heating and cooling rates will be developed for the EULAG model in order to systematically study effects for a set of cloud-resolving simulations. (abridged text)