Monika Prasch - Academia.edu (original) (raw)

Papers by Monika Prasch

In mountain areas glaciers are a considerable component of the water cycle. Water stored as glaci... more In mountain areas glaciers are a considerable component of the water cycle. Water stored as glacier ice in alpine headwatersheds and released during melting periods is an important contribution for water supply management, hydropower generation and reservoir management. Meltwater production is related to the glaciated area, therefore the retreat of glaciers forced by climate change is one of the most significant impacts. The integrative research project Brahmatwinn (www.brahmatwinn.uni-jena.de) focuses on regional hydrological modeling and the determination of the impact of future climate change on the water balance in the twinning catchments of the Upper Danube and the Upper Brahmaputra River. In these mesoscale catchments the extension of most glaciers is below the spatial resolution of the model grid. To simulate the future changes in ice thickness and glaciated area under climate change scenarios at this resolution, a subscale approach is applied. Therefore the physically based ...

The amount of liquid water in snow characterizes the wetness of a snowpack. Its temporal evolutio... more The amount of liquid water in snow characterizes the wetness of a snowpack. Its temporal evolution plays an important role for wet-snow avalanche prediction, as well as the onset of meltwater release and water availability estimations within a river basin. However, it is still a challenge and a not yet satisfyingly solved issue to measure the liquid water content (LWC) in snow with conventional in situ and remote sensing techniques. We propose a new approach based on the attenuation of microwave radiation in the L-band emitted by the satellites of the Global Positioning System (GPS). For this purpose, we performed a continuous low-cost GPS measurement experiment at the Weissfluhjoch test site in Switzerland, during the snow melt period in 2013. As a measure of signal strength, we analyzed the carrier-to-noise power density ratio (C/N0) and developed a procedure to normalize these data. The bulk volumetric LWC was determined based on assumptions for attenuation, reflection and refraction of radiation in wet snow. The onset of melt, as well as daily melt-freeze cycles were clearly detected. The temporal evolution of the LWC was closely related to the meteorological and snow-hydrological data. Due to its non-destructive setup, its cost-efficiency and global availability, this approach has the potential to be implemented in distributed sensor networks for avalanche prediction or basin-wide melt onset measurements.

ABSTRACT http://www.hfph.de/igp/proceedings2011

I would also like to express deep thanks to Prof. Dr. Karsten Schulz for his generous acceptance ... more I would also like to express deep thanks to Prof. Dr. Karsten Schulz for his generous acceptance of the efforts associated with the second review of this thesis. I am deeply grateful to Prof. Dr. Ulrich Strasser for sharing his knowledge of snow and ice modelling with me. He also provided me with an insight into various scientific procedures and introduced me to Dr. Markus "Wasti" Weber of the Commission for Glaciology of the Bavarian Academy of Sciences and Humanities. I want to express my great thanks to Dr. Markus "Wasti" Weber for intensively discussing the basics of the details of glacier modelling with me and for our constructive teamwork Acknowledgements V with the SURGES glacier model. With his obliging help, many questions concerning glaciers were answered. It was a pleasure for me to work with him on the same issues.

Regional Assessment of Global Change Impacts, 2016

ABSTRACT The retarded runoff from the seasonal snow cover in the Alps and its forelands plays an ... more ABSTRACT The retarded runoff from the seasonal snow cover in the Alps and its forelands plays an important role for entire watersheds like the Danube River Basin which is one of Europe’s most important catchments reaching from the Eastern Alps down to the Black Sea. For hydrological purposes, information about the snow water equivalent and the amount and temporal onset of melt water release are highly important to estimate river runoff and water availability within a catchment. However, in mountainous areas it is still a problem to get these data due to no or only sparse in-situ snow measurements. In general, a wider and more cost-efficient measurement network would improve e.g. low-flow and flood forecast models as well as water supply and hydropower estimates and would therefore also serve as a necessary basin-wide preparatory adaptation measure due to climate change impacts on snow which tend to cause an earlier runoff peak in spring. We will report on a new low-cost NAVSTAR-GPS (Navigational Satellite Timing and Ranging Global Positioning System) measurement experiment to derive continuous information on snow, especially on the liquid water content. During the snow covered periods of 2012-2013 and 2013-2014 we performed non-destructive snow measurements with low-cost GPS receivers and antennas above and underneath the snowpack at a high-alpine test site in Switzerland. The freely available GPS L1-band signals (1.57542 GHz) including the carrier-to-noise power density ratio of each of the 32 GPS satellites are partly absorbed and scattered by the snowpack, especially when it becomes wet. The attenuation of the GPS signals serves therefore as a good qualitative indicator for snow wetness and daily melt-freeze cycles. The GPS-derived snow wetness data were compared to meteorological and snow-hydrological data and agreed well in their temporal occurrence. To derive the liquid water content a mixing formula for wet snow related to the GPS signal attenuation was applied. Due to its cost-efficiency and global availability, this approach might have the potential to be implemented in a basin-wide snow measurement network. Preliminary results of this new measurement technology will be presented.

Regional Assessment of Global Change Impacts, 2016

EXTENDED ABSTRACT Alpine mountains are of global importance in providing downstream freshwater, m... more EXTENDED ABSTRACT Alpine mountains are of global importance in providing downstream freshwater, much of it stored as snow several months of the year. This function of a temporal storage of precipitation and its delayed release during melt is one of the key characteristics of a mountain snow cover. In a changing climate, the latter process is supposed to be modified in its temporal dynamics. This important objective is investigated in the frameworks of the projects Brahmatwinn (http://www.brahmatwinn.uni-jena.de) as well as GLOWA Danube (www.glowa-danube.de) by determining the impact of future climate change on the hydrology of the Upper Danube catchment with its alpine headwaters. For a distributed simulation of the snow cover evolution for both present as well as for future scenarios we apply the model PROMET (Processes of Radiation, Mass and Energy Transfer), the land surface core of the model framework DANUBIA. In its current version it is a distributed, physical, non-calibrated ...

ABSTRACT http://www.hfph.de/igp/proceedings2011

Regional Assessment of Global Change Impacts, 2016