David Loibl

Glaciers and equilibrium line altitudes of the eastern Nyainqêntanglha Range, SE Tibet

A set of maps that illustrate the key results of a study on glaciers and late Holocene glacier change in the eastern Nyainqêntanglha Range, southeastern Tibet, is presented. The cartographic challenge was to present this information in a way that focuses on the most important findings but retains as much detail as possible. The layout is based on two main maps showing two different sets of information for the same area; one map of glacier types and distribution and one map of calculated equilibrium line altitudes (ELA). Additionally, two inset maps provide a regional topographic overview and information on ELA change since the Little Ice Age maximum glacier advance. Through this approach, the viewer is able to combine the different sets of information individually for different parts of the study area. Insights into the complex couplings of climate, relief, and glaciers can thus be obtained. The maps reveal heterogeneous spatial patterns of glacier and ELA distributions. These reflect the interplay of the high-mountain topography and the primary moisture sources, the Indian Summer Monsoon and the East Asian Summer Monsoon. Specifically, luv-lee effects and the channeling of monsoonal air masses through the valley system can be observed at catchment to regional scales. The patterns of ELA change since the Little Ice Age indicate that glacier sensitivity to climate change is decreasing toward regions with increasingly continental climate in the eastern Nyainqêntanglha Range.

High-resolution geomorphological map of a low mountain range near Aachen, Germany

A high-resolution geomorphological map covering the central part of a low mountain range close to the city of Aachen in the border region of western Germany and eastern Belgium is presented. It is conceptually based on the ‘Geomorphologische Karte 1:25,000’ (GMK) which was developed by German researchers in the 1970s and 1980s but differs from the original concept in terms of data acquisition, processing and map layout in order to overcome some problems of classical geomorphological maps. These comprise time consuming field work, inflexible paper-based map creation, and the resulting poor legibility due to extremely high information density. All mapping was performed in a Geographic Information Systems (GIS) environment on the basis of a 1 m LiDAR digital elevation model to reduce the time and cost needed for map production. The scale of the map is 1:5000 and thus increased by a factor of five in comparison to the original GMK to make sure no crucial information is lost through cartographic generalization. The layout was adjusted to fit the larger scale, resulting in an improvement of the morphometric information value and a strengthening of the GMKs construction kit concept. In comparison to the original GMK concept, the methodology yields benefits for the production of geomorphological maps by reducing the effort necessary to collect and manage data, improving the spatial accuracy, and enhancing the flexibility regarding data management and map layout.

A modelling approach to reconstruct Little Ice Age climate from remote-sensing glacier observations in southeastern Tibet

Abstract We use numerical modelling of glacier mass balance combined with recent and past glacier extents to obtain information on Little Ice Age (LIA) climate in southeastern Tibet. We choose two glaciers that have been analysed in a previous study of equilibrium-line altitudes (ELA) and LIA glacier advances with remote-sensing approaches. We apply a physically based surface energy- and mass-balance model that is forced by dynamically downscaled global analysis data. The model is applied to two glacier stages mapped from satellite imagery, modern (1999) and LIA. Precipitation scaling factors (PSF) and air temperature offsets (ATO) are applied to reproduce recent ELA and glacier mass balance (MB) during the LIA. A sensitivity analysis is performed by applying seasonally varying gradients of precipitation and air temperature. The calculated glacier-wide MB estimate for the period 2000–12 is negative for both glaciers (–992±366 kgm–2 a–1 and –1053±258 kgm–2 a–1). Relating recent and LIA PSF/ATO sets suggests a LIA climate with ~8–25% increased precipitation and ~1–2.5°C lower mean air temperature than in the period 2000–12. The results only provide an order of magnitude because deviations in other input parameters are not considered.