21 research outputs found
An ablation model for debris-covered ice: the case study of Venerocolo Glacier (Italian Alps)
We developed a simple model to estimate ice ablation under a debris cover. The ablation process is modelled using energy and mass conservation equations for debris and ice and heat conduction, driven by input of either i) debris surface temperature or ii) radiation fluxes, and solved through a finite difference scheme computing the conductive heat flux within the supra-glacial debris layer. For model calibration, input and validation, we used approximately bi-weekly surveys of ice ablation rate, debris cover temperature, air temperature and solar incoming and upwelling radiation during for Summer 2007. We calibrated the model for debris thermal conductivity using a subset of ablation data and then we validated it using another subset. Comparisons between calculated and measured values showed a good agreement (RMSE = 0.04 m w.e., r = 0.79), thus suggesting a good performance of the model in predicting ice ablation. Thermal conductivity was found to be the most critical parameter in the proposed model, and it was estimated by debris temperature and thickness, with value changing along the investigated ablation season. The proposed model may be used to quantify buried ice ablation given a reasonable assessment of thermal conductivity
Variations of Lys Glacier (Monte Rosa Massif, Italy) from the Little Ice Age to the Present from Historical and Remote Sensing Datasets
Alpine glaciers respond to climate imbalance by adjusting their mass and length. In turn, these changes modify the glacial and periglacial environment, leading to increased supraglacial debris cover, the development of glacial lakes and glacier fragmentation. In this research, we investigated the evolution of Lys Glacier (Monte Rosa Group), by studying length, area and volume changes, and evolution of its supraglacial debris cover and proglacial lakes by means of historical sources and high-resolution aerial and satellite orthophotos. Lys Glacier retreated almost continuously, by nearly 2 km, from its maximum Little Ice Age position. More recently, the glacier lost 11.91% of its area between 1975 and 2014 and underwent fragmentation in 2009. Over the same period, glacier fragmentation and tongue stagnation affected the formation and rapid growth of a series of ice-contact lakes and led to a non-linear debris cover evolution. The glacier was also subjected to strong volume losses, with more than 135 m thinning on the ablation tongue from 1991 to 2014. Analysis of the meteorological records (1927–present) from the closest weather station reveals a considerable increase in average annual temperatures by more than 1°C from the mean of 1971–1989 to the mean of 1990–2017
Investigation of Brain Activation Patterns Related to the Feminization or Masculinization of Body and Face Images across Genders
Previous studies demonstrated sex-related differences in several areas of the human brain, including patterns of brain activation in males and females when observing their own bodies and faces (versus other bodies/faces or morphed versions of themselves), but a complex paradigm touching multiple aspects of embodied self-identity is still lacking. We enrolled 24 healthy individuals (12 M, 12 F) in 3 different fMRI experiments: the vision of prototypical body silhouettes, the vision of static images of the face of the participants morphed with prototypical male and female faces, the vision of short videos showing the dynamic transformation of the morphing. We found differential sexual activations in areas linked to self-identity and to the ability to attribute mental states: In Experiment 1, the male group activated more the bilateral thalamus when looking at sex congruent body images, while the female group activated more the middle and inferior temporal gyrus. In Experiment 2, the male group activated more the supplementary motor area when looking at their faces; the female group activated more the dorsomedial prefrontal cortex (dmPFC). In Experiment 3, the female group activated more the dmPFC when observing either the feminization or the masculinization of their face. The defeminization produced more activations in females in the left superior parietal lobule and middle occipital gyrus. The performance of all classifiers built using single ROIs exceeded chance level, reaching an area under the ROC curves > 0.85 in some cases (notably, for Experiment 2 using the V1 ROI). The results of the fMRI tasks showed good agreement with previously published studies, even if our sample size was small. Therefore, our functional MRI protocol showed significantly different patterns of activation in males and females, but further research is needed both to investigate the gender-related differences in activation when observing a morphing of their face/body, and to validate our paradigm using a larger sample
Inventory of glaciers and glacial lakes of the Central Karakoram National Park (CKNP – Pakistan)
This study presents a map reporting valuable information on the cryosphere of the Central Karakoram National Park (CKNP, the largest protected area of Pakistan and the highest park in the world). All the information is provided considering the CKNP as a whole, and in detail by dividing it into five basins (i.e. Shigar, Hunza, Shyok, Upper Indus, and Gilgit). The glacier inventory reports 608 ice bodies covering 3680 km2 ( 3c35% of the CKNP area), with a total glacier volume of ca. 532 km3. In addition, we modeled the meltwater from glacier ice ablation over the period 23 July to 9 August 2011. The total melt amount is ca. 1.5 km3. Finally, we considered glacial lakes (202 water-bodies, covering 4 km2). For these latter glacier features, we also analyzed their potentially dangerous conditions and two lakes were found having such conditions
Inventory of glaciers and glacial lakes of the central Karakoram National Park (Pakistan) as a contribution to know and manage mountain freshwater resource.
In this study, we reported valuable information on the cryosphere of the Central Karakoram National Park (CKNP, the largest protected area of Pakistan and the highest park all over the world). In fact, in addition to the glacier inventory, we also estimated the glacier volume and we modeled the amount of meltwater derived from glacier ice ablation during a 18-day summer period (23 July–9 August 2011, time window where also field melt measurements were performed thus enabling a crosscheck of the obtained results). Moreover, glacial lakes were considered as well; for these latter glacier features we also analyzed their potentially dangerous conditions. All these information are given considering the CKNP as a whole and in detail by dividing it into five basins (i.e. Shigar, Hunza, Shyok, Upper Indus and Gilgit). As regards the CKNP as a whole, 608 glaciers are found with a total area of 3682.1 ± 61.0 km2, ~35% of the CKNP area. Analyzing in detail the five basins included in the CKNP area, they reflect the overall conditions regarding glacier distribution per size class, terminus elevation, length, and thickness. The widest basin (for number of ice bodies, glacier extent and ice volume) is the Shigar basin, where the largest glaciers are present (among which Baltoro Glacier), and the smallest one is the Gilgit basin. Finally, the highest number of debris-covered glaciers is located in the Shyok basin (62 glaciers). During 18 days in summer 2011, we quantified a total water magnitude of 1.54 km3 derived from ice melting. Even if we considered a relatively short period, this water volume equals ~11% of the reservoir capacity of the Tarbela Dam. In addition to glacier information, we provided glacial lake occurrence, as these ephemeral water bodies can develop into actual glacial risk conditions, which makes it important to list them and to survey them over time. The information reported in this study would provide base for future monitoring of glacial lakes and GLOFs and for planning and prioritizing disaster mitigation efforts in the park. In fact, even if the Potentially Dangerous Glacial Lakes (PDGLs) identified in the park territory are only 2, they are located in a high vulnerable and fragile area and the recent history suggests us to survey over time these water bodies to avoid losses of human lives and destructions of villages and communities. Moreover, many other supraglacial lakes identified in the park area could develop into conditions of PDGLs thus suggesting to prosecute the lake monitoring and to develop early strategies for risk mitigations and disaster management
Glacier area stability in the Central Karakoram National Park (Pakistan) in 2001–2010: The “Karakoram Anomaly” in the spotlight
The Karakoram Range is one of the most glacierized mountain regions in the world, and glaciers there are an important water resource for Pakistan. The attention paid to this area is increasing because its glaciers remained rather stable in the early twenty-first century, in contrast to the general glacier retreat observed worldwide on average. This condition is also known as “Karakoram Anomaly”. Here we focus on the recent evolution of glaciers within the Central Karakoram National Park (CKNP, area: *13,000 km2) to assess their status in this region with respect to the described anomaly. A glacier inventory was produced for the years 2001 and 2010, using Landsat images. In total, 711 ice-bodies were detected and digitized, covering an area of 4605.9 ± 86.1 km2 in 2001 and 4606.3 ± 183.7 km2 in 2010, with abundant supraglacial debris cover. The difference between the area values of 2001 and 2010 is not significant (+0.4 ± 202.9 km2), confirming the anomalous behavior of glaciers in this region. The causes of such an anomaly may be various. The increase of snow cover areas from 2001 to 2011 detected using MODIS snow data; the reduction of mean summer temperatures; and the augmented snowfall events during 1980–2009 observed at meteorological stations and confirmed by the available literature, are climatic factors associated with positive mass balances. Because the response of glacier area change to climate variation is very slow for large glaciers, the presence of some of the largest glaciers of the Karakoram Range in this region might have delayed observed effects of such climate change so far, or alternatively, the change may not be sufficient to drive an actual area increase. In this context, improved understanding the role of debris cover, meltwater ponds, and exposed ice cliffs on debris-covered glaciers, and surging glaciers (which are also found abundant here), are required is still an issue to clarify the mechanisms behind the Karakoram Anomaly
The new Inventory of Italian Glaciers: Present knowledge, applied methods and preliminary results
We presented a proposal of a new Inventory of Italian Glaciers as well as the present knowledge, the applied
methods and the preliminary results