AK Hochschulmathematikdidaktik

Bericht über die Sitzung des Arbeitskreises mit den beiden Vorträgen von Rolf Biehler und Reinhard Hochmuth sowie von Claudia Böttinger sowie Informationen zu Publikationen und Tagunge

Arbeitskreis: HochschulMathematikDidaktik

Der Bericht blickt auf die vergangene Herbsttagung 2016 in Würzburg sowie der Arbeitskreissitzung auf der Jahrestagung der GDM in Potsdam zurück. Zudem gibt er einen Ausblick auf die kommende Herbsttagung

Arctic Mission Benefit Analysis: impact of sea ice thickness, freeboard, and snow depth products on sea ice forecast performance

Assimilation of remote-sensing products of sea ice thickness (SIT) into sea ice–ocean models has been shown to improve the quality of sea ice forecasts. Key open questions are whether assimilation of lower-level data products such as radar freeboard (RFB) can further improve model performance and what performance gains can be achieved through joint assimilation of these data products in combination with a snow depth product. The Arctic Mission Benefit Analysis system was developed to address this type of question. Using the quantitative network design (QND) approach, the system can evaluate, in a mathematically rigorous fashion, the observational constraints imposed by individual and groups of data products. We demonstrate the approach by presenting assessments of the observation impact (added value) of different Earth observation (EO) products in terms of the uncertainty reduction in a 4-week forecast of sea ice volume (SIV) and snow volume (SNV) for three regions along the Northern Sea Route in May 2015 using a coupled model of the sea ice–ocean system, specifically the Max Planck Institute Ocean Model. We assess seven satellite products: three real products and four hypothetical products. The real products are monthly SIT, sea ice freeboard (SIFB), and RFB, all derived from CryoSat-2 by the Alfred Wegener Institute. These are complemented by two hypothetical monthly laser freeboard (LFB) products with low and high accuracy, as well as two hypothetical monthly snow depth products with low and high accuracy.On the basis of the per-pixel uncertainty ranges provided with the CryoSat-2 SIT, SIFB, and RFB products, the SIT and RFB achieve a much better performance for SIV than the SIFB product. For SNV, the performance of SIT is only low, the performance of SIFB is higher and the performance of RFB is yet higher. A hypothetical LFB product with low accuracy (20&thinsp;cm uncertainty) falls between SIFB and RFB in performance for both SIV and SNV. A reduction in the uncertainty of the LFB product to 2&thinsp;cm yields a significant increase in performance.Combining either of the SIT or freeboard products with a hypothetical snow depth product achieves a significant performance increase. The uncertainty in the snow product matters: a higher-accuracy product achieves an extra performance gain. Providing spatial and temporal uncertainty correlations with the EO products would be beneficial not only for QND assessments, but also for assimilation of the products.</p

Zur Rolle der Fachhochschulen im deutschen Hochschulsystem

Fachhochschulen stellen einen unverzichtbaren Bestandteil des deutschen Hochschulsystems dar. […] Die Entwicklung der deutschen Fachhochschulen hat inzwischen zu einer enormen Spreizung dieses Sektors geführt; einigen ist es gelungen, sogar universitäre Charakteristika überzeugender als so manche Universität zu verwirklichen. Dennoch kann es nicht das Bestreben von Fachhochschulen sein, universitätsähnlich oder sogar universitätsgleich zu werden. Aufgrund ihrer finanziellen, personellen und sächlichen Ausstattung wären sie dann eine „Universität zweiter Klasse“; ein Wettbewerb auf Augenhöhe ist nicht möglich und von der Politik übrigens auch nicht gewollt! Die Fachhochschulen sollten sich vielmehr auf ihre Stärken berufen und sich in der Wahrnehmung ihrer wissenschafts-, gesellschafts- und wirtschaftsrelevanten Aufgaben weiterentwickeln. Ihr Vermögen steckt in der Ausrichtung auf den Bedarf, sie agieren eher nachfrage- als angebotsorientiert. Dieser Weg sollte konsequent und ideenreich weitergegangen werden. (DIPF/Orig.

Variability of winter sea ice in Greenland-Iceland-Norwegian Sea in a regionally coupled climate model

To investigate interaction and feedback mechanisms of different climate components in the Arctic, we use a regional atmosphere-ocean model setup, consisting of the global ocean - sea-ice model MPIOM with high resolution in the Arctic coupled to the regional atmosphere model REMO. We perform an experiment using reanalysis data from the European Center of Medium Range Weather Forecast (ERA-40) as external forcing to simulate the climate of the last decades (1958-2001). We analyze this experiment in order to improve our understanding of ocean - sea-ice - atmosphere processes at the marginal ice zone in the Greenland-Iceland-Norwegian (GIN) Sea. We present first results on the variability of the marginal ice zone in GIN Sea, where in the last century the commonly named Arctic Odden has been observed frequently, an ice tongue with large daily variability in size and shape. We are interested in the dynamics of the formation of such a sea-ice tongue and show that in our model advection of ice rather than new ice formation is the driving mechanism

A Simple Shift of Elliptic Grid Generation Towards Orthogonality

From the interpretation of the two-dimensional elliptic grid generation equation in conservative form as a force balance a method is devised for an iterative update of the control functions, which drives the grid towards orthogonality, not only at the boundaries but in the total field. The method has also been successfully used to effectively reduce grid line skewness in the physical domain, when adaptation is performed in a parametric domain.It is readily implemented into existing codes and easily extended to three dimensions

Grid Adaptation to multiple auto-scaled solution features

A solution adaptive generation method for structured grids will be presented that consists of a hyperbolic grid generator and an adaptive weight composer being linked to a p.d.e. solver. Grids are generated in an efficient way from the solution of a second order hyperbolic system. The ability of the grid generator to track a specified solution feature has been previously established. Here, we focus on a simple construction of the weight function to capture multiple solution features automatically. The resulting adapted grid will rely solely on the solution without any need for geometry dependent clustering or for a user specified background distribution. The suggested procedure may beware the user from choosing in an ad hoc manner a possibly unadequate adaptation function. The method is demonstrated on an example of viscous hypersonic flow around a hyperboloid/-cone configuratio