18 research outputs found
Assessing Greenland Ice Sheet meltwater losses at the pixel and drainage basin scale
No full textThe Greenland Ice Sheet (GrIS) is expected to increase its contributions to sea level rise with atmospheric warming, and it is important to accurately predict future sea level change. Surface meltwater runoff losses, modulated by surface albedo, are two dominant uncertainties in future GrIS sea level rise estimates. The first component of this study characterizes surface albedo in the lower ablation zone, a key variable controlling the surface energy and mass balance of the GrIS, and an important parameter in regional climate models (RCMs). This analysis is expanded in a second study to evaluate satellite albedo retrievals and assess its ability to resolve sub-pixel spatial variability of ablation area albedo. In situ spectral albedo data collected along a transect, Moderate Resolution Imaging Spectroradiometer (MODIS) daily albedo product, and high spatial resolution WorldView-2 (WV-2) data are utilized in these two studies. The results show that the distribution of dominant ice surface types (e.g., snow, bare ice, light-absorbing impurities, and streams) act as an additional mechanism for controlling ablation zone albedos. This can significantly impact seasonal and inter-annual changes in ablation zone albedo, and subsequent melt. These findings have important implications for current RCMs, which don’t fully integrate a seasonally evolving ice surface type’s albedo scheme. The second study demonstrates over spatially heterogeneous surfaces, such as in the ablation zone, that a multiple ‘point-to-pixel’ comparison, utilizing multiple ground albedo observations coinciding with a satellite pixel, is superior to the frequently used single ‘point-to-pixel’ comparison. This points to the significance of evaluating the spatial representativeness of ground albedo sites (e.g., automatic weather stations) prior to validation of satellite or model-derived albedos. The second component of this study quantifies meltwater runoff losses, a dominant, yet understudied term of GrIS mass loss, at the drainage-basin scale. To do this, the Modèle Atmosphérique Régionale (MAR) RCM discharge estimates are compared with proglacial river discharge observations at three drainage basins – Thule, Watson, and Nuuk – located north-to-south in west Greenland. I find that MAR poorly resolves daily discharge variability in the Nuuk and Thule basins, but is better able to capture variability at longer time averages. Model-observation agreement is reduced during peak discharge events. The model-observation discharge discrepancies are likely due to an underestimation of cloud cover, from an overestimation of downward shortwave radiation. The discrepancies of model and measurements during peak discharge events is important to understand as they are expected to occur more frequently with continued warming. In a fourth study, annual and daily peak river discharge was unprecedented at all basins in the extreme melt season of 2012. Exceptional flows in all three rivers were observed corresponding with two ice sheet wide surface melt episodes in mid- and late-July 2012. These results suggest the need to further study runoff processes at the local-, basin- and continental-scale not fully captured by current RCMs. These four studies collectively contribute information that will allow for better understanding of Greenland’s complex hydrologic system. Finally, these studies provide the framework to improve physical representation of meltwater runoff and albedo components used in RCMs to project changes in Greenland’s mass loss, and subsequent contributions to sea level rise.Ph.D.Includes bibliographical referencesby Samiah Moustaf
Evidence of Meltwater Retention within the Greenland Ice Sheet
No full textGreenland ice sheet mass losses have increased in recent decades with more than half of these attributed to surface meltwater runoff. However, the magnitudes of englacial storage, firn retention, internal refreezing and other hydrologic processes that delay or reduce true water export to the global ocean remain less understood, partly due to a scarcity of in situ measurements. Here, ice sheet surface meltwater runoff and proglacial river discharge between 2008 and 2010 near Kangerlussuaq, southwestern Greenland were used to establish sub- and englacial meltwater storage for a small ice sheet watershed (36–64 km2). This watershed lacks significant potential meltwater storage in firn, surface lakes on the ice sheet and in the proglacial area, and receives limited proglacial precipitation. Thus, ice sheet surface runoff not accounted for by river discharge can reasonably be attributed to retention in sub- and englacial storage. Evidence for meltwater storage within the ice sheet includes (1) characteristic dampened daily river discharge amplitudes relative to ice sheet runoff; (2) three cold-season river discharge anomalies at times with limited ice sheet surface melt, demonstrating that meltwater may be retained up to 1–6 months; (3) annual ice sheet watershed runoff is not balanced by river discharge, and while near water budget closure is possible as much as 54% of melting season ice sheet runoff may not escape to downstream rivers; (4) even the large meltwater retention estimate (54%) is equivalent to less than 1% of the ice sheet volume, which suggests that storage in en- and subglacial cavities and till is plausible. While this study is the first to provide evidence for meltwater retention and delayed release within the Greenland ice sheet, more information is needed to establish how widespread this is along the Greenland ice sheet perimeter.Peer reviewe
Understanding Greenland ice sheet hydrology using an integrated multi-scale approach
No full textImproved understanding of Greenland ice sheet hydrology is critically important for assessing its impact on current and future ice sheet dynamics and global sea level rise. This has motivated the collection and integration of in situ observations, model development, and remote sensing efforts to quantify meltwater production, as well as its phase changes, transport, and export. Particularly urgent is a better understanding of albedo feedbacks leading to enhanced surface melt, potential positive feedbacks between ice sheet hydrology and dynamics, and meltwater retention in firn. These processes are not isolated, but must be understood as part of a continuum of processes within an integrated system. This letter describes a systems approach to the study of Greenland ice sheet hydrology, emphasizing component interconnections and feedbacks, and highlighting research and observational needs.Peer reviewe
Corrections to “D2D-V2X-SDN: Taxonomy and Architecture Towards 5G Mobile Communication”
Full text linkIn the above article [1], the following author bios must be updated as their posts and positions were upgraded, and the profile picture of Bassem F. Felemban was previously incorrect.Scopu
Correction: Politicization of COVID-19 health-protective behaviors in the United States: Longitudinal and cross-national evidence
Full text linkThere is an error in affiliation 54 for author Adil Samekin. The correct affiliation 54 is: School of Liberal Arts, M. Narikbayev KAZGUU University, Nur-Sultan, Kazakhstan.</p
ML-based Smart Voice Analysis for Healthy and Pathological Voice Detection
Full text linkVoice pathology is increasing dramatically, especially due to unhealthy social habits, being too much talkative, age factor or some kind of pathology in throat. Normally the people who speaks a lot for example, teachers or announcers etc. suffer from voice pathology in their elderly age. A research-oriented simulation project is developed, which will help a general physician to identify this voice pathology. It is work of specialist ENT doctor. This will help and assist general physician to identify pathology and to refer the patient to the specialist doctor. For implementing the work, a hybrid system is developed which is based on two models. For assisting general physician, the model first detects the pathology i.e. normal voice or pathological voice. In the second model the system will classify the type of disease present in the patient. The main objective of this research work is to investigate commonly used features available for feature extraction of voice pathology classification and detection. Then train the system using various machine learning techniques that can provide us with better pathology detection and classification rate. This paper focusses on developing an accurate Mel frequency Cepstral Coefficient feature extraction technique for classifying and detecting voice pathologies using a German Saarbrucken voice database. The system is trained by using four different kinds of machine learning algorithms which are Naïve Bayes, Random Forest, Support Vector Machine, K nearest neighbor and then finding out which algorithm perform well in both of these models. In this research validating the results and comparing it with previous research work is analyzed. Analysis of several different diseases and techniques are also provided in these studies
Health trends in Canada 1990-2019:An analysis for the Global Burden of Disease Study
Full text linkMonitoring trends in key population health indicators is important for informing health policies. The aim of this study was to examine population health trends in Canada over the past 30 years in relation to other countries. We used data on disability-adjusted life years (DALYs), years of life lost (YLL), years lived with disability, life expectancy (LE), and child mortality for Canada and other countries between 1990 and 2019 provided by the Global Burden of Disease Study. Life expectancy, age-standardized YLL, and age-standardized DALYs all improved in Canada between 1990 and 2019, although the rate of improvement has leveled off since 2011. The top five causes of all-age DALYs in Canada in 2019 were neoplasms, cardiovascular diseases, musculoskeletal disorders, neurological disorders, and mental disorders. The greatest increases in all-age DALYs since 1990 were observed for substance use, diabetes and chronic kidney disease, and sense organ disorders. Age-standardized DALYs declined for most conditions, except for substance use, diabetes and chronic kidney disease, and musculoskeletal disorders, which increased by 94.6%, 14.6%, and 7.3% respectively since 1990. Canada's world ranking for age-standardized DALYs declined from 9th place in 1990 to 24th in 2019. Canadians are healthier today than in 1990, but progress has slowed in Canada in recent years in comparison with other high-income countries. The growing burden of substance abuse, diabetes/chronic kidney disease, and musculoskeletal diseases will require continued action to improve population health. [Abstract copyright: © 2024. The Author(s) under exclusive license to The Canadian Public Health Association.
Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
No full textAuthor Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017 (Nature Medicine, (2020), 26, 5, (750-759), 10.1038/s41591-020-0807-6)
No full textAn amendment to this paper has been published and can be accessed via a link at the top of the paper.</p
Characterising acute and chronic care needs: insights from the Global Burden of Disease Study 2019
No full textChronic care manages long-term, progressive conditions, while acute care addresses short-term conditions. Chronic conditions increasingly strain health systems, which are often unprepared for these demands. This study examines the burden of conditions requiring acute versus chronic care, including sequelae. Conditions and sequelae from the Global Burden of Diseases Study 2019 were classified into acute or chronic care categories. Data were analysed by age, sex, and socio-demographic index, presenting total numbers and contributions to burden metrics such as Disability-Adjusted Life Years (DALYs), Years Lived with Disability (YLD), and Years of Life Lost (YLL). Approximately 68% of DALYs were attributed to chronic care, while 27% were due to acute care. Chronic care needs increased with age, representing 86% of YLDs and 71% of YLLs, and accounting for 93% of YLDs from sequelae. These findings highlight that chronic care needs far exceed acute care needs globally, necessitating health systems to adapt accordingly.
© 2025. The Author(s)
