distributed mass balance modelling on two neighbouring glaciers in ortles cevedale italy from 2004 to 2009

AbstractA 6 year application of an enhanced temperature-index mass-balance model to Careser and La Mare glaciers, Eastern Italian Alps, is presented. The two glaciers exhibit very different characteristics, and a comprehensive dataset of distributed mass-balance measurements was used to test the model performance. The model was run using meteorological data acquired outside the glaciers. The work was focused on two main aspects: (1) the development of a morphological redistribution procedure for snow, and (2) the comparison of three different melt algorithms proposed in the literature. The results show that the simple method proposed for snow redistribution can greatly improve simulation of winter balance, and further improvements would be achievable by collecting data on inaccessible and high-altitude areas. All three melt formulations displayed a good skill level and very similar results in modelling the mass-balance distribution over glacier areas, with slightly better results from a multiplicative algorithm in capturing the vertical balance gradient. The simulation errors are related to aspect and elevation, and tend to be spatially aggregated. Some assumptions concerning the spatial and temporal distribution of air temperature and incoming solar radiation, although reasonable and widely used in the literature, may be responsible for this aggregation. Hence, there is a need to further investigate the processes that regulate the distribution of melt energy, and that appear to control the current deglaciation phase in this area

Towards the de\ufb01nition of a new river water line for North-Eastern Italy

In the last decades there has been active research on the relation between the stable isotopic composition of precipitation and climate variations at the regional scale. Particularly, the analysis of meteoric water lines is an important tool to understand climate processes at the local/regional scale. In this view, considering the strict relation between the isotopic composition of river water and the one of precipitation, surface running waters (i.e. rivers, streams, creeks) and their catchments can be considered as \u201cnatural pluviometers\u201d. In this study the analysis of the isotopic composition of surface waters was carried out in order to develop a new meteoric water line of North-East Italy. The dataset includes samples collected between 2012 and 2016 from i) small catchments, typically < 30 Km2 (Ressi Creek, Bridge Creek and Vauz Creek, Noce Bianco stream, Posina river), where it is easier to relate the stream water isotopic composition to distinct meteoric end-members (e.g., rainfall,snowmeltandglaciermelt);andii)largebasins(Adige:12,100Km2 andPo:71,000Km2)whichintegrate multiple components giving information at the regional scale. Preliminary results show that distinct river water lines are characterized by different slopes and intercepts. The slopes vary between 5.46 and 8.02, whereas the intercepts vary between -9.15 and 11.82. In particular river meteoricwaterlinesde\ufb01nedforRessiCreek(\u3b4Dh\uaf7.48 \u3b418O+10.27,n=831;R2 =0.88)andNoceBiancostream (\u3b4Dh\uaf7.66 \u3b418O+7.27, n=484; R2 = 0.95) con\ufb01rm the similarity with the meteoric line developed for northern Italy. On the contrary, the isotopic composition of streams in small (< 10 Km2) snow-dominated catchments (Bridge Creek and Vauz Creek) deviate from the North Italy meteoric line due to the important contribution of snowmelt that is typically characterized by a different isotopic signature compared to the precipitation input. River water lines for large basins (Po and Adige) are characterized by slopes and intercepts in the range of the Global Meteoric Water Line. Finally, it is important to emphasize that the current dataset, progressively updated, represents a snapshot of a short monitoring period and that future investigations are useful to highlight seasonal variations and on-going environmental changes

Suitability of ground-based SfM-MVS for monitoring glacial and periglacial processes

Photo-based surface reconstruction is rapidly emerging as an alternative survey technique to lidar (light detection and ranging) in many fields of geoscience fostered by the recent development of computer vision algorithms such as structure from motion (SfM) and dense image matching such as multi-view stereo (MVS). The objectives of this work are to test the suitability of the ground-based SfM-MVS approach for calculating the geodetic mass balance of a 2.1km2 glacier and for detecting the surface displacement of a neighbouring active rock glacier located in the eastern Italian Alps. The photos were acquired in 2013 and 2014 using a digital consumer-grade camera during single-day field surveys. Airborne laser scanning (ALS, otherwise known as airborne lidar) data were used as benchmarks to estimate the accuracy of the photogrammetric digital elevation models (DEMs) and the reliability of the method. The SfM-MVS approach enabled the reconstruction of high-quality DEMs, which provided estimates of glacial and periglacial processes similar to those achievable using ALS. In stable bedrock areas outside the glacier, the mean and the standard deviation of the elevation difference between the SfM-MVS DEM and the ALS DEM was-0.42 \ub1 1.72 and 0.03 \ub1 0.74 m in 2013 and 2014, respectively. The overall pattern of elevation loss and gain on the glacier were similar with both methods, ranging between-5.53 and + 3.48 m. In the rock glacier area, the elevation difference between the SfM-MVS DEM and the ALS DEM was 0.02 \ub1 0.17 m. The SfM-MVS was able to reproduce the patterns and the magnitudes of displacement of the rock glacier observed by the ALS, ranging between 0.00 and 0.48 m per year. The use of natural targets as ground control points, the occurrence of shadowed and low-contrast areas, and in particular the suboptimal camera network geometry imposed by the morphology of the study area were the main factors affecting the accuracy of photogrammetric DEMs negatively. Technical improvements such as using an aerial platform and/or placing artificial targets could significantly improve the results but run the risk of being more demanding in terms of costs and logistics

Pinus cembra L. tree-ring data as a proxy for summer mass-balance variability of the Careser Glacier (Italian Rhaetian Alps)

Glacial extent and mass-balance are sensitive climate proxies providing solid information on past climatic conditions. However, series of annual mass balance measurements of more than sixty years are scarce. To our knowledge, this is the first time the latewood density data (MXD) of the Swiss stone pine (Pinus cembra L.) has been used to reconstruct the summer mass balance (Bs) of an Alpine glacier. The MXD-based Bs well correlates with a Bs reconstruction based on the May to September temperature. Winter precipitation has been used as independent proxy to infer the winter mass balance and to obtain an annual mass balance (Bn) estimate dating back to the glaciological year 1811/12. The reconstructed MXD/precipitation-based Bn well correlates with the data both of the Careser and of other Alpine glaciers measured by the glaciological method. A number of critical issues should be considered in both proxies including nonlinear response of glacial mass balance to temperature, bedrock topography, ice thinning and fragmentation, MXD acquisition and standardization methods, and finally the “divergence problem” responsible for the recent reduced dendroglaciological reconstructions using this stable and reliable proxy

A Pinus cembra L. tree-ring record for late spring to late summer temperature in the Rhaetian Alps, Italy

Abstract Ongoing climate change strongly affects high-elevation environments in the European Alps, influencing the cryosphere and the biosphere and causing widespread retreat of glaciers and changes in biomes. Nevertheless, high-elevation areas often lack long meteorological series, and global datasets cannot represent local variations well. Thus, proxy data, such as tree rings, provide information on past climatic variations from these remote sites. Although maximum latewood density (MXD) chronologies provide better temperature information than those based on tree-ring width (TRW), MXD series from the European Alps are lacking. To derive high-quality temperature information for the Rhaetian Alps, Pinus cembra L. trees sampled at approximately 2000 m a.s.l. were used to build one MXD chronology spanning from 1647 to 2015. The MXD data were significantly and highly correlated with seasonal May-September mean temperatures. The MXD chronology showed a generally positive trend since the middle of the 19th century, interrupted by short phases of climatic deterioration in the beginning of the 20th century and in the 1970s, conforming with the temperature trends. Our results underline the potential for using Pinus cembra L. MXD to reconstruct mean temperature variations, especially during the onset and latter part of the growing season, providing additional information on parts of the growing season not inferred from TRW. Future studies on MXD for this species will increase the availability of temporal and spatial data, allowing detailed climate reconstructions

The Ortles ice cores: uncovering an extended climate archive from the Eastern Alps

During the last half century, oxygen and hydrogen stable isotope content of ice cores has been extensively used for air temperature reconstructions. The most suitable glaciers of the Alpine area, most exclusively in the Western Alps, havebeen utilizedfor icecoring formore thanfour decades.The paleoclimatic potential of theEastern Alps isstilllargelyunexploitedandwasscarcelyutilizedinthepastmainlybecauseofthelowerelevation(comparedto Western Alps) and hence the difficulty to find glaciers in cold conditions. The warming temperature trend appears to be particularly pronounced in the Alps, threatening the preservation of the glaciated areas and creating a sense of urgency in retrieving climatic archives before it is too late. In autumn 2011, four deep cores were drilled on Mt Ortles, South Tyrol, Italy, at 3859 m a.s.l. An extensive reconstructed temperature record for the Ortles summit, based on the surrounding meteorological station data, is available for the last 150 years, while an automatic weather station had been operating from 2011 to 2015 in proximity of the drilling site. The new ice core chronology, based on 210Pb, tritium, beta emissions analysis and 14C measurements of the particulate organic carbon, indicates that the bottom ice is 7000 years old, making it the second most extended glaciological archive ever retrieved in the Alps. The three equally long ice cores have been analyzed for oxygen and hydrogen stable isotopes throughout their length, and the goal is to create an Ortles stacked record for d18O and dD and compare the isotopic data to instrumental temperatures and to other Alpine records. Since 2008, several snow pits were dug in proximity of the drilling site during summer, when the temperature can oftenexceedthemeltingpoint.Theisotopicprofilesofthe2015snowpit,dugattheendofanexceptionallywarm summer,showhowtheisotopesignalisnowaffectedbythepost-depositionalprocessesthathaveoccurredduring that summer