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Due to climate warming, the glaciers of the Tibetan Plateau have experienced rapid mass loss and the patterns of glacier changes have exhibited high spatiotemporal heterogeneity, especially in interior areas. As the largest ice field within the Tibetan Plateau, the Puruogangri Ice Field has attracted a lot of attention from the scientific community. However, relevant studies that are based on satellite data have mainly focused on a few periods from 2000–2016. Long-term and multiperiod observations remain to be conducted. To this end, we estimated the changes in the glacier area and mass balance of the Puruogangri Ice Field over five subperiods between 1975 and 2021, based on multisource remote sensing data. Specifically, we employed KH-9 and Landsat images to estimate the area change from 1975 to 2021 using the band ratio method. Subsequently, based on KH-9 DEM, SRTM DEM, Copernicus DEM and ZY-3 DEM data, we evaluated the glacier elevation changes and mass balance over five subperiods during 1975–2021. The results showed that the total glacier area decreased from 427.44 ± 12.43 km2 to 387.87 ± 11.02 km2 from 1975 to 2021, with a decrease rate of 0.86 km2 a−1. The rate of area change at a decade timescale was −0.74 km2 a−1 (2000–2012) and −1.00 km2 a−1 (2012–2021). Furthermore, the rates at a multiyear timescale were −1.23 km2 a−1, −1.83 km2 a−1 and −0.42 km2 a−1 for 2012–2015, 2015–2017 and 2017–2021, respectively. In terms of the glacier mass balance, the region-wide results at a two-decade timescale were −0.23 ± 0.02 m w.e. a−1 for 1975–2000 and −0.29 ± 0.02 m w.e. a−1 for 2000–2021, indicating a sustained and relatively stable mass loss over the past nearly five decades. After 2000, the loss rate at a decade timescale was −0.04 ± 0.01 m w.e. a−1 for 2000–2012 and −0.17 ± 0.01 m w.e. a−1 for 2012–2021, indicating an increasing loss rate over recent decades. It was further found that the mass loss rate was −0.12 ± 0.02 m w.e. a−1 for 2012–2015, −0.03 ± 0.01 m w.e. a−1 for 2015–2017 and −0.40 ± 0.03 m w.e. a−1 for 2017–2021. These results indicated that a significant portion of the glacier mass loss mainly occurred after 2017. According to our analysis of the meteorological measurements in nearby regions, the trends of precipitation and the average annual air temperature both increased. Combining these findings with the results of the glacier changes implied that the glacier changes seemed to be more sensitive to temperature increase in this region. Overall, our results improved our understanding of the status of glacier changes and their reaction to climate change in the central Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The elastic response of solid earth to glacier and ice sheet melting, the most important consequences of climate change, is a contemporaneous uplift. Here, we use interferometric synthetic aperture radar (InSAR) measurements to detect crustal deformation and mass loss near the Helheim glacier, one of the largest glaciers in southeastern Greenland. The InSAR time series of Sentinel-1 data between April 2016 and July 2020 suggest that there is a maximum cumulative displacement of ~6 cm in the line of sight (LOS) direction from the satellite to the ground near Helheim. We use an exponentially decreasing model of the thinning rate, which assumes that the mass loss starts at the lower-elevation terminal region of the glacier and continues to the higher-elevation interior. A linear inversion of the derived crustal uplift in the vicinity of bedrock using this model for surface loading in an elastic half-space suggests a mass loss of 8.33 Gt/year, which agrees with the results from other studies. [ABSTRACT FROM AUTHOR]

We introduce the first version of the Stochastic Ice-sheet and Sea-level System Model (StISSM v1.0), which adds stochastic parameterizations within a state-of-the-art large-scale ice sheet model. In StISSM v1.0, stochastic parameterizations target climatic fields with internal variability, as well as glaciological processes exhibiting variability that cannot be resolved at the spatiotemporal resolution of ice sheet models: calving and subglacial hydrology. Because both climate and unresolved glaciological processes include internal variability, stochastic parameterizations allow StISSM v1.0 to account for the impacts of their high-frequency variability on ice dynamics, and on the long-term evolution of modeled glaciers and ice sheets. StISSM v1.0 additionally includes statistical models to represent surface mass balance and oceanic forcing as autoregressive processes. Such models, once appropriately calibrated, allow users to sample irreducible uncertainty in climate prediction without the need of computationally expensive ensembles from climate models. When combined together, these novel features of StISSM v1.0 enable quantification of irreducible uncertainty in ice sheet model simulations, and of ice sheet sensitivity to noisy forcings. We detail the implementation strategy of StISSM v1.0, evaluate its capabilities in idealized model experiments, demonstrate its applicability at the scale of a Greenland ice sheet simulation, and highlight priorities for future developments. Results from our test experiments demonstrate the complexity of ice sheet response to variability, such as asymmetric and/or non-zero mean responses to symmetric, zero-mean imposed variability. They also show differing levels of projection uncertainty for stochastic variability in different processes. These features are in line with results from stochastic experiments in climate and ocean models, as well as with the theoretical expected behavior of noise-forced non-linear systems. [ABSTRACT FROM AUTHOR]

We investigate the continuity and stability of GRACE and GRACE Follow-On satellite gravimetric missions by assessing the ocean mass budget at global scale over 2005–2020, focusing on the last years of the record (2015–2020) when GRACE and GRACE Follow-On faced instrumental problems. For that purpose, we compare the global mean ocean mass estimates from GRACE and GRACE Follow-On to the sum of its contributions from Greenland, Antarctica, land glaciers and terrestrial water storage estimated with independent observations. A significant residual trend of -1.60 ± 0.36 mm/yr over 2015–2018 is observed. We also compare the gravimetry-based global mean ocean mass with the altimetry-based global mean sea level corrected for the thermosteric contribution. We estimate and correct for the drift of the wet tropospheric correction of the Jason-3 altimetry mission computed from the on-board radiometer. It accounts for about 40 % of the budget residual trend beyond 2015. After correction, the remaining residual trend amounts to -0.90 ± 0.78 mm/yr over 2015–2018 and -0.96 ± 0.48 mm/yr over 2015–2020. GRACE and GRACE Follow-On data might be responsible for part of the observed non-closure of the ocean mass budgets since 2015. However, we show that significant interannual variability is not well accounted for by the data used for the other components of the budget, including the thermosteric sea level and the terrestrial water storage. Besides, missing contributions from the evolution of the deep ocean or the atmospheric water vapour may also contribute. [ABSTRACT FROM AUTHOR]

The glaciers in Arctic Archipelago of Svalbard, located in the hotspot of global warming, are sensitive to climate change. The assessment of glacier mass balance in Svalbard is one of the hotspots in Arctic research. In this study, we use the laser altimetry ICESat-2 data to investigate the elevation and mass change of Svalbard from 2019 to 2021 by a hypsometric approach. It is shown that the Svalbard-wide elevation change rate is −0.775 ± 0.225 m yr−1 in 2019–2021, corresponding to the mass change of −14.843 ± 4.024 Gt yr−1. All regions exhibit a negative mass balance, and the highest mass loss rates are observed at Northwestern Spitsbergen. Compared with ICESat/ICESat-2 (2003–2008 to 2019) and Cryosat-2 (2011–2017) periods, the elevation change from 2019 to 2021 has accelerated, with an increase by 158.3% and 31.5%, respectively, leading to equilibrium line altitude increasing to 750 m. Among the seven subregions, four are accelerated. It is shown that the overall accelerated glacier mass loss in Svalbard is expected to be caused by increasing surge events and temperature rise. [ABSTRACT FROM AUTHOR]

Glacier mass balance models are needed at sites with scarce long-term observations to reconstruct past glacier mass balance and assess its sensitivity to future climate change. In this study, North American Regional Reanalysis (NARR) data were used to force a physically based, distributed glacier mass balance model of Saskatchewan Glacier for the historical period 1979–2016 and assess its sensitivity to climate change. A 2-year record (2014–2016) from an on-glacier automatic weather station (AWS) and historical precipitation records from nearby permanent weather stations were used to downscale air temperature, relative humidity, wind speed, incoming solar radiation and precipitation from the NARR to the station sites. The model was run with fixed (1979, 2010) and time-varying (dynamic) geometry using a multitemporal digital elevation model dataset. The model showed a good performance against recent (2012–2016) direct glaciological mass balance observations as well as with cumulative geodetic mass balance estimates. The simulated mass balance was not very sensitive to the NARR spatial interpolation method, as long as station data were used for bias correction. The simulated mass balance was however sensitive to the biases in NARR precipitation and air temperature, as well as to the prescribed precipitation lapse rate and ice aerodynamic roughness lengths, showing the importance of constraining these two parameters with ancillary data. The glacier-wide simulated energy balance regime showed a large contribution (57 %) of turbulent (sensible and latent) heat fluxes to melting in summer, higher than typical mid-latitude glaciers in continental climates, which reflects the local humid "icefield weather" of the Columbia Icefield. The static mass balance sensitivity to climate was assessed for prescribed changes in regional mean air temperature between 0 and 7 ∘ C and precipitation between -20 % and + 20 %, which comprise the spread of ensemble Representative Concentration Pathway (RCP) climate scenarios for the mid (2041–2070) and late (2071–2100) 21st century. The climate sensitivity experiments showed that future changes in precipitation would have a small impact on glacier mass balance, while the temperature sensitivity increases with warming, from -0.65 to -0.93 m w.e. a -1 ∘ C -1. The mass balance response to warming was driven by a positive albedo feedback (44 %), followed by direct atmospheric warming impacts (24 %), a positive air humidity feedback (22 %) and a positive precipitation phase feedback (10 %). Our study underlines the key role of albedo and air humidity in modulating the response of winter-accumulation type mountain glaciers and upland icefield-outlet glacier settings to climate. [ABSTRACT FROM AUTHOR]

Snow density estimates as a function of depth are used for understanding climate processes, evaluating water accumulation trends in polar regions, and estimating glacier mass balances. The common and interpretable physically derived differential equation models for snow density are piecewise linear as a function of depth (on a transformed scale); thus, they can fail to capture important data features. Moreover, the differential equation parameters show strong spatial autocorrelation. To address these issues, we allow the parameters of the physical model, including random change points over depth, to vary spatially. We also develop a framework for functionally smoothing the physically motivated model. To preserve inference on the interpretable physical model, we project the smoothing function into the physical model's spatially varying null space. The proposed spatially and functionally smoothed snow density model better fits the data while preserving inference on physical parameters. Using this model, we find significant spatial variation in the parameters that govern snow densification. [ABSTRACT FROM AUTHOR]

Most efforts to characterize the size and composition of the mantle that complements the continental crust have assumed that the mid‐ocean ridge basalt (MORB) source is the incompatible‐element depleted residue of continental crust extraction. The use of Nd isotopes to model this process led to the conclusion that the "depleted MORB reservoir" is confined to the upper ∼30% of the mantle, leaving the lower mantle in a more "primitive" state. Here, we use Nb/U and Ta/U to evaluate mass and composition of the mantle reservoir residual to continent extraction and find that it exceeds 60% of the total mantle. Thus, the (Nb, Ta)/U‐based mass balance conflicts with the ε(Nd)‐based mass balance, and this invalidates the classical 3‐reservoir silicate Earth model (continental crust, depleted mantle, and primitive mantle). Including the combined MORB + ocean island basalt (OIB) sources in the ε(Nd)‐based mass balance does not reconcile the conflict as it would require their average ε(Nd) to be ≤3.0, much lower than observed MORB + OIB ε(Nd) averages. We resolve this conflict by invoking an additional, "early enriched reservoir" (EER), formed prior to extraction of significant continental crust, but now hidden or lost. This EER differs from EERs previously invoked by having no Nb‐Ta anomaly. We suggest that it originated as an early mafic crust, which had unfractionated (Nb, Ta)/U but fractionated Sm/Nd ratios. The corresponding "early depleted" reservoir generated the present‐day continental crust and the "residual mantle" MORB‐OIB reservoir, which occupies at least 63% of the present‐day mantle and is only moderately depleted in incompatible trace elements. Plain Language Summary: The Earth's continental crust makes up only about half a percent of Earth's mass, but it contains a large portion of its total budget of uranium and thorium, which produce much of Earth's interior heat. In making the crust, these elements have been extracted via melts and volcanism from Earth's mantle. But what portion of the mantle was involved in making the continents? Previously, geochemists concluded that only its uppermost 30% was involved, leaving the lower two‐thirds of the mantle essentially untouched. The measure used for this estimate has been the difference in the isotope ratios of neodymium, 143Nd/144Nd, between crust and mantle. However, when we use an alternative measure for the same calculation, namely the ratio of niobium to uranium, Nb/U, we find the depleted mantle fraction to be greater than 60%. We therefore need an Earth model that involves an additional "reservoir" with crust‐like Nd isotopes but mantle‐like Nb/U. We model this as an early Earth basaltic crust, which may have been lost to space, or may now be hidden at the base of the mantle. A buried ancient crust might well explain the large density/temperature anomalies recently discovered at the base of the mantle by seismologists. Key Points: A new assessment of the depleted mantle (DM) mass (>63%) based on (Nb, Ta)/U conflicts with conventional estimates using Nd isotopes (<50%)This invalidates the classic 3‐reservoir silicate Earth (continental crust, DM, and primitive mantle)The observable, present‐day mantle was permanently depleted by segregation or loss of an early enriched reservoir [ABSTRACT FROM AUTHOR]

The Patagonian Icefields (Northern and Southern Patagonian Icefields) are the largest ice masses in the Andes Cordillera. Despite its importance, little is known about the main mechanisms that underpin the interaction between these ice masses and climate. Furthermore, the nature of large-scale climatic control over the surface mass variations of the Patagonian Icefields still remains unclear. The main aim of this study is to understand the present-day climatic control of the surface mass balance (SMB) of the Patagonian Icefields at interannual timescales, especially considering large-scale processes. We modeled the present-day (1980–2015) glacioclimatic surface conditions for the southern Andes Cordillera by statistically downscaling the output from a regional climate model (RegCMv4) from a 10 km spatial resolution to a 450 m resolution grid, and then using the downscaled fields as input for a simplified SMB model. Series of spatially averaged modeled fields over the Patagonian Icefields were used to derive regression and correlation maps against fields from the ERA-Interim reanalysis. Years of relatively high SMB are associated with the establishment of an anomalous low-pressure center near the Drake Passage, the Drake low, that induces an anomalous cyclonic circulation accompanied with enhanced westerlies impinging the Patagonian Icefields, which in turn leads to increases in the precipitation and the accumulation over the icefields. Also, the Drake low is thermodynamically maintained by a core of cold air that tends to reduce the ablation. Years of relatively low SMB are associated with the opposite conditions. We found low dependence of the SMB on main atmospheric modes of variability (El Niño-Southern Oscillation, Southern Annular Mode), revealing a poor ability of the associated indices to reproduce interannual variability of the SMB. Instead, this study highlights the Drake Passage as a key region that has the potential to influence the SMB variability of the Patagonian Icefields. [ABSTRACT FROM AUTHOR]

Mid-latitude alpine caves preserve a record of past solid precipitation during winter, locally spanning several centuries to millennia. Dating organic macro-remains trapped in ice layers allows the determination of timing and duration of past periods of positive and negative ice mass balance. We present here the largest comparative study of ice cave sites yet published, using Bayesian age-modelling on a database comprising 107 radiocarbon dates, spread over eight caves in the Austrian Alps. We show that periods of positive mass balance coincide with past glacier advances. We find organic and macro-remain rich layers dated to the Medieval Climate Anomaly (between 850 and 1200 CE) marking widespread ice retreat. We demonstrate positive ice mass balance at all studied sites for the Little Ice Age, coinciding with the largest glacier advances in the Holocene between 1400 and 1850 CE. At the sites with records spanning over 2000 years, positive mass balance is also observed during the periods from 300 BCE to 100 CE and 600–800 CE. These subterranean ice deposits show widespread evidence of accelerated negative mass balances in recent years and their record is under imminent threat of disappearing. [ABSTRACT FROM AUTHOR]

Mountain glaciers, including the poorly examined ones in the Lake Karakul Basin, are considered the most vulnerable part of the cryosphere directly reacting to the changing climatic conditions. The most recent aerial imaging and single field surveys of the Lake Karakul Basin glaciation were carried out as late as in 1953. The investigation of the basin's glaciers thus is of high scientific relevance, including in terms of glaciology and climatology. The article describes the calculations of the surface mass balance (SMB) of Glacier No.139 in the Lake Karakul Basin allowing, based on the findings, to assess the degree of climate change impact on the glaciation in the target zone, as well as the potential changes in the state of glaciers in the future. During 2018-2019, the mass balance of Glacier No.139, located in the basin's southwestern section, amounted to -0.26 mwe. The data obtained from the Karakul Weather Station allowed establishing that the climate in the target watershed is harshly cold with little snow in winter and mild summer, and the bulk of precipitation occurring in the warm season. Due to the fact that in the past and until recently no glacier mass observations were conducted in the target zone, the research findings can serve as initial data to expand the scientific and applied knowledge, as well as contribute to enhancing the accuracy of glacier dynamics modeling in the area. [ABSTRACT FROM AUTHOR]

Glacier monitoring in Switzerland has resulted in some of the longest and most complete data series globally. Mass balance observations at individual locations, starting in the 19th century, are the backbone of the monitoring as they represent the raw and original glaciological data demonstrating the response of snow accumulation and snow/ice melt to changes in climate forcing. So far, however, the variety of sources of historic measurements has not been systematically processed and documented. Here, we present a new complete and extensive point glacier mass balance dataset for the Swiss Alps that provides attributes for data quality and corresponding uncertainties. Original sources were digitized or re-assessed to validate or to correct existing entries and to identify metadata. The sources of data are highly diverse and stem from almost 140 years of records, originating from handwritten field notes, unpublished project documents, various digital sources, published reports, and meta-knowledge of the observers. The project resulted in data series with metadata for 63 individual Swiss glaciers, including more than 60 000 point observations of mass balance. Data were systematically analysed and homogenized, e.g. by supplementing partly missing information based on correlations inferred from direct measurements. A system to estimate uncertainty in all individual observations was developed indicating that annual point balance is measured with a typical error of 0.07 m water equivalent (w.e.), while the average error in winter snow measurements is 0.20 m w.e. Our dataset permits further investigating the climate change impacts on Swiss glaciers. Results show an absence of long-term trends in snow accumulation over glaciers while melt rates have substantially increased over the last 3 decades. The complete dataset is available at DOI 10.18750/massbalance.point.2021.r2021 (GLAMOS, 2021). [ABSTRACT FROM AUTHOR]

There was sufficient evidence to indicate a nearly balanced glacier mass change (termed glacier anomaly) for Karakoram Mts. since the 1970s, in contrast to worldwide glacier mass losses caused by climate warming. Recently, this anomalous phenomenon was detected over the neighboring western Kunlun and Pamir Mts. However, the southeastern limit of this glacier anomaly remains uncertain, owing to the paucity of glacier mass balance observations across the interior and northern Tibetan Plateau (INTP). In this study, we presented a decadal glacier mass balance estimation in the INTP by differencing the SRTM DEM with the topographic data produced from TanDEM-X bistatic InSAR images. From 2000 to 2012, decade-average glacier mass balances of between −0.339 ± 0.040 and 0.237 ± 0.078 m w.e. yr−1 were detected over 22 glacierized areas. Significantly, we found a gradient and switch of glacier mass loss over the southeastern portion to glacier mass gain over the northwestern portion. This varying spatial pattern illustrates that glacier anomaly has existed over the northwestern or even central zone of the INTP since the early 21st century. This study provides important evidence for the model simulation of both glacier evolution and atmospheric circulations in investigating the prevailing mechanism of the regional anomalous phenomenon. [ABSTRACT FROM AUTHOR]

This study uses a mass balance model and economic analysis technique to present an estimation of roofing areas and storage tank capacity for Rainwater Harvesting (RWH) system. The water-saved benefits were estimated using the monthly rainfall of over 39 years from 1981 to 2020 and five roofing areas. The proposed roof-storage-ratio method presents the minimum requirement of roof area and storage tank size when the ratio value is closer to 1. The benefit-cost ratio and percentage of reliability indicated the optimal roofing areas ranging between 200 and 300 m2 for storage tank capacity between 20 and 25 m3, with a minimum discount rate of 5%. The increased capacity of storage tank and roofing area would also be a potential factor to increase the investment cost for installing the RWH system. [ABSTRACT FROM AUTHOR]

• Modern seawater has a homogeneous δ87Rb with mean value at 0.13 ± 0.04‰ (2SD, n = 13);. • Authigenic phillipsite and clays can be isotopically light sinks of oceanic Rb cycling with δ87Rb at around −0.06‰ to 0.03‰. • The exchangeable fraction in sediments has δ87Rb of −0.07 ± 0.05‰ (2SD, n = 6), reflecting preferential absorption of 85Rb by deep-sea sediment. • The δ87Rb of the porewaters are homogeneous (0.08‰ to 0.14‰) and similar to seawater, suggesting a limited modification by authigenic silicates in the study region. The rubidium (Rb) isotope system has the potential for tracing water–silicate interactions and providing information on the global Rb cycling. However, the Rb isotope compositions of modern seawater and its major inputs and outputs remain poorly understood. Here we measured Rb isotope compositions of seawaters, pelagic clay sediments and porewaters from the western and central equatorial Pacific Ocean. Our results show that the δ87Rb of modern seawater is homogeneous (0.13 ± 0.04‰; 2SD, n = 13) and higher than both the local sediments (-0.17‰ to 0.03‰) and the bulk lithosphere (Δ87Rb seawater-UCC = 0.27‰). The Rb in pelagic clay sediments is primarily associated with silicates (> 90%) and partially with exchangeable fractions (∼ 4%). The exchangeable fractions display relatively lower δ87Rb (-0.07 ± 0.05‰; 2SD, n = 6). Meanwhile, the correlation between K/Rb and δ87Rb of bulk sediments, along with investigations on the clay sized particles (δ87Rb = -0.06‰), represents that lithogenic silicates have relatively low K/Rb and δ87Rb close to the UCC while formation of authigenic phillipsite or clays can result in higher bulk K/Rb (up to 930) and δ87Rb (up to 0.03‰). The δ87Rb of both authigenic silicates and absorbed fractions in deep–sea sediments are lower than seawater, which can partially contribute to the removal of isotopically light Rb from seawater. The δ87Rb of the measured marine porewaters are approximately homogeneous (0.08‰ to 0.14‰) and similar to seawater. The result consistent with previous K isotope investigation in this region with limited impact of authigenic silicates. Using a mass balance estimation in a steady state with isotope data, the flux of sediment removal for Rb in the ocean is about 2.2 – 12.0 × 107 kg/year. [ABSTRACT FROM AUTHOR]

Greenland's peripheral glaciers and ice caps (GICs) contribute significant amounts of meltwater to the oceans but also affect local economies and livelihoods. Here we created multi-temporal geodetic elevation change datasets to compute mass changes for 6149 glaciers around the entire periphery of Greenland. These glaciers have lost a total of at least 276 ± 55 Gt of ice, or 0.76 ± 0.15 mm sea level equivalent, from their ablation areas between 1978 and 2015. If we assume no mass loss within accumulation areas, then the mean mass balance has been at least −0.10 ± 0.02 m w.e. yr−1. In general, west Greenland glaciers have had a more negative mass balance and experienced accelerated mass loss since 2006 (x 2.7 in south west region, x 5.6 in central west region). Conversely, east Greenland glaciers have generally experienced a decrease in the rate of mass loss. Lake-terminating glaciers have experienced the most negative mass balance, exacerbated by the occurrence of debris cover. These findings quantify great spatial heterogeneity, give context to the recent history of mass loss from GICs, and suggest the importance of including local glacier properties within glacier evolution models. • Mean mass balance of -0.1 ± 0.02 m w.e yr-1 between 1978 and 2015 (276 ± 55 Gt, 0.76 ± 0.15 mm sea level rise equivalent) • Acceleration of mass loss in west Greenland since the 1980s and deceleration in east Greenland since 2000 • Lake-terminating glaciers and debris-covered glaciers have the highest rates of mass loss [ABSTRACT FROM AUTHOR]

Few studies have assessed a comprehensive understanding of how the seasonal and interannual variability and trends of the surface mass balance (SMB), including the influence of atmospheric river (ARs), are governed by the climate on the South Shetland Islands (SSI) glaciers located in the northerly Antarctic Peninsula (AP). To address this gap, we comprehensively analyzed the correlations and regressions between seasonal and annual SMB with regional to global climate indices and a state-of-the-art AR tracking database from 1980 to 2019. The daily and monthly SMB was obtained from two physical glaciological models, which was verified against 19 years of annual and seasonal glacier-wide SMB observations available in three glaciers (Johnsons, Hurd, and Bellingshausen), showing a good ability to capture interannual and seasonal variability. Results indicate a low dependence of the SMB on main atmospheric modes of variability (e.g., El Niño-Southern Oscillation and the Southern Annular Mode), and a moderate dependence on regional climate indices based on atmospheric pressure anomalies and sea surface temperature anomalies over the Drake Passage. Furthermore, our findings reveal that ARs have different effects on the SMB depending on the season. For example, winter ARs tend to boost accumulation due to increased snowfall, while summer ARs tend to intensify surface melting due to increased sensible heat flux. Our study highlights the Drake Passage as a key region that has the potential to influence the interannual and seasonal variability of the SMB and other climate variables, such as air temperature and snowfall over the SSI. We suggest that future work should consider this region to better understand the past, present and future climate changes on the SSI and surrounding areas. [Display omitted] • Interannual SMB trend links to AP surface temperature shifts. • Positive years SMB are associated with low-pressure systems over Drake and Weddell Sea. • Interannual SMB variability has a weak correlation with SAM and ENSO. • Winter (Summer) ARs typically lead to positive (negative) SMB conditions. [ABSTRACT FROM AUTHOR]

La Chinchilla granite (∼3.75 km2) is an epizonal pluton intruded during the Lower Carboniferous in Sierra de Velasco, Sierras Pampeanas, northwestern Argentina. Three facies have been distinguished in the pluton (equigranular, porphyritic and fine-grained border zone facies), being equigranular and porphyritic the main two granite types, which host abundant millimeter to < 2 m sized miarolitic pegmatites and pockets of simple granitic mineralogy (quartz + albite + microcline + micas) ± beryl. Micrometer-sized accessory magmatic species are monazite-(Ce), several high field strength element oxide species, ilmenite, cassiterite (1), fluorapatite and fluorite. Primary Li-bearing micas with variable degrees of late to postmagmatic replacement occur in abundances that range from ∼2 to 7 %. Textural evidence and mineral chemistry allow to distinguish between early granitic and late bladed miarolitic micas. The mineral chemistry composition of the primary micas shows members of the siderophyllite-polylithionite series. Replacing phases are Li-muscovite (phengite). Electron probe microanalyses of primary micas of both main granite types suggest that these are compositionally distinct intrusives. According to mica chemistry, the porphyritic unit is more enriched in Li than the equigranular granite. The equigranular unit with interconnected miarolitic texture was more intensely affected by fluid-rock interaction processes and is significantly richer in U and Be. An F–Na rich fluid phase caused strong albitization during late miarolitic stages, along with crystallization of polylithionite, fluorite, pyrochlore group species and cassiterite (2). In terms of mass balance, the phengite replacement process is characterized by the conservation of Si, Al and K, a slight gain of Na and Ba, and a systematic loss of orderly decreasing Fe > F > Li > Mn > Ti > Mg > Zn. Likely, the muscovite-forming fluid was the same simultaneously involved in the hydrothermal alteration of high field strength element accessory species, largely included in primary micas, which generated secondary U- and Nb-rich species such as carlosbarbosaite. The hydrothermal late miarolitic to postmagmatic fluid-mineral replacement of primary magmatic micas released significant amounts of Li, of which about 59 wt % of the Li 2 O content of protholithic micas (i.e., 1 to 2.4 wt % Li 2 O) was inherited by replacing Li-bearing muscovite and the remaining 41 wt % was released from the system. It is calculated that ∼1.5 km3 of La Chinchilla body would have expelled ∼0.38 million tons of Li 2 O, just considering than only 30 % of primary siderophyllite-polylithionite was muscovitized. Such a Li 2 O tonnage was likely transferred to the paleohydrological cycle during Carboniferous times, when the La Chinchilla stock was still undergoing its cooling down path. Currently, evidence of the final fate of mobilized Li is lacking. • Mineral chemistry of magmatic Li-Fe micas from two likely synmagmatic granite units suggests different melt compositions. • Phengitization of magmatic siderophyllite - polylithionite micas is an effective postmagmatic process for lithium release. • The phengitization fluid was involved in the breakdown and subsequent mobilization of HFSE from accessory species. • Neoformed phengite can take up part of the original Li 2 O content, but a significant amount is released after replacement. • About 0.38 million tons of Li 2 O were extracted from ∼ 1.5 km3 of granite, likely mobilized into the paleohydrological system. [ABSTRACT FROM AUTHOR]

Understanding the effects of the snow ratio on glacier mass balance under variable climatic conditions is crucial for predicting how glaciers will respond to climate change, and for forecasting water supplies to surrounding lowland areas. Due to recent climate change, the historical annual snow ratio of the Dongkemadi (DKMD) Glacier showed a significant increasing trend (0.0538% a−1, p < 0.05), and an abrupt upward change in 1977 due to decreasing precipitation concentration. Snow ratios with fixed precipitation concentration and nonwarming climate scenarios were calculated to isolate the impact of the snow ratio on glacier mass balance. Under nonwarming conditions, the snow ratio showed little variability, ranging from 88.4% to 99.9%. Glacier modeling results comparing five snow ratio scenarios from 1961 to 2009 showed three main features as follows. (i) Glacier mass balance was low and more sensitive to a warming climate for lower snow ratio scenarios. (ii) The difference in mass balance between the scenarios fluctuated, but generally increased with time. Spatially, the ablation area change was larger (0.4 km2), and the equilibrium line altitude was higher (5.9 m) in scenarios with lower snow ratios. (iii) The change in net shortwave radiation was the main reason for changes in glacial melt, and the albedo played a key role in controlling the difference of glacier energy balance between snow ratio scenarios. Rain increment only accounted for about 20%–33% of meltwater increment. Overall, this study provides valuable information to evaluate how snow ratios impact the mass balance of glaciers with ongoing climate change. [ABSTRACT FROM AUTHOR]

The reliability of weather radar data in real-time flood forecasting and early warning system remain ambivalent due to high uncertainty in Quantitative Precipitation Forecasts (QPF). In this study, a methodology is presented with the objective to improve the flood forecasting results with the application of radar rainfall calculated in three different ways. The QPF radar rainfall forecast data of four typhoon events in Fèngshān River Basin, Taiwan, were simulated using the WASH123D numerical model. The simulated results were corrected using a physical real-time correction technique and compared with direct simulation without correction for all three QPF calculation methods. According to model performance evaluation criteria, in the third method of QPF calculation, flood peak error was the lowest in all three methods, indicating better results for flood forecasting and can be used for flood early warning systems. The impact of the real-time correction technique was assessed using mass balance analysis. It was found that flow change is between 16% and 42% from direct simulation, indicating being on the safe side in case of a flood warning. However, the impact of the real-time physical correction on the water level itself is in a reasonable range. Still, QPF rainfall correction/calculation is more important to obtain accurate results for flood forecasting. Therefore, the application of real-time correction to correct the model water level has a certain degree of credibility, which is the mass balance of the model. This approach is recommended for flood forecasting early warning systems. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to evaluate the toxicity and biodegradation potential of oil hydrocarbons contaminated soil samples obtained from different depths at an oil refinery station area. An approach involving chemical, microbiological, respirometry and ecotoxicity assessment of soil polluted by oil hydrocarbons was adopted, in order to determine the biodegradability of pollutants and ecotoxicological effects of natural attenuation strategy. Methods: The ecotoxicity of soil samples was evaluated using an ostracod test kit and a seed germination test. The results of the phytotoxicity assay were expressed as a percentage of seedling emergence and as the relative yield of fresh and dry biomass compared to control plants. The intrinsic biodegradation potential of the contaminated soil was examined using a Micro-Oxymax respirometer. Intrinsic biodegradation rates were estimated from the slopes of linear regressions curves plotted for cumulative O2 uptake. The obtained values were then entered in the mass balance equation for the stoichiometric reaction of hydrocarbon decomposition and converted per kg of soil per day. Results: Although the tested contaminants were biodegradable in the respirometric assay, they were slightly to moderately toxic to plants and extremely toxic to ostracods. The noxious effects raised with the increased concentration of contaminants. The monocotyledonous oat was more tolerant to higher concentrations of oil hydrocarbons than the other test plants, indicating its greater suitability for soil reclamation purposes. Conclusion: By assessing phytotoxicity and effect on ostracod mortality and progress of soil self-decontamination process, proper approach of reclamation of demoted area can be provided. [ABSTRACT FROM AUTHOR]

Rainfall forecasting is essential to manage water resources and make timely decisions to mitigate adverse effects related to unexpected events. Considering that rainfall drivers can change throughout the year, one approach to implementing forecasting models is to generate a model for each period in which the mechanisms are nearly constant, e.g., each season. The chosen predictors can be more robust, and the resulting models perform better. However, it has not been assessed whether the approach mentioned above offers better performance in forecasting models from a practical perspective in the tropical Andean region. This study evaluated quarterly, semiannual and annual models for forecasting monthly rainfall anomalies in an Andean basin to show if models implemented for fewer months outperform accuracy; all the models forecast rainfall on a monthly scale. Lagged rainfall and climate indices were used as predictors. Support vector regression (SVR) was used to select the most relevant predictors and train the models. The results showed a better performance of the annual models mainly due to the greater amount of data that SVR can take advantage of in training. If the training of the annual models had less data, the quarterly models would be the best. In conclusion, the annual models show greater accuracy in the rainfall forecast. [ABSTRACT FROM AUTHOR]

Record highs of meltwater production at the surface of the Greenland ice sheet have been recorded with a high recurrence over the last decades. Those melt seasons with longer durations, larger intensities, or with both increased length and melt intensity have a direct impact on the surface mass balance of the ice sheet and on its contribution to sea level rise. Moreover, the surface melt also affects the ice dynamics through the meltwater lubrication feedback. It is still not clear how the meltwater lubrication feedback impacts the long-term ice velocities on the Greenland ice sheet. Here we take a modeling approach with simplified ice sheet geometry and climate forcings to investigate in more detail the impacts of the changing characteristics of the melt season on ice dynamics. We model the ice dynamics through the coupling of the Double Continuum (DoCo) subglacial hydrology model with a shallow shelf approximation for the ice dynamics in the Ice-sheet and Sea-level System Model (ISSM). The climate forcing is generated from the ERA5 dataset to allow the length and intensity of the melt season to be varied in a comparable range of values. Our simulations present different behaviors between the lower and higher part of the glacier, but overall, a longer melt season will yield a faster glacier for a given runoff value. However, an increase in the intensity of the melt season, even under increasing runoff, tends to reduce glacier velocities. Those results emphasize the complexity of the meltwater lubrication feedback and urge us to use subglacial drainage models with both inefficient and efficient drainage components to give an accurate assessment of its impact on the overall dynamics of the Greenland ice sheet. [ABSTRACT FROM AUTHOR]

Tracking and quantifying the moisture sources of precipitation in different drainage basins in the Tibetan Plateau (TP) help to reveal basin-scale hydrological cycle characteristics under the interactions between the westerlies and Indian summer monsoon (ISM) systems and to improve our understanding on the mechanisms of water resource changes in the 'Asian Water Tower' under climate changes. Based on a Eulerian moisture tracking model (WAM-2) and three atmospheric reanalysis products (ERA-I, MERRA-2, and JRA-55), the contributions of moisture sources to the precipitation in six major sub-basins in the TP were tracked during an approximately 35-year period (1979/1980–2015). The results showed that in the upper Indus (UI), upper Tarim River (UT), and Qaidam Basin (QB), the moisture sources mainly extended westward along the mid-latitude westerlies to the western part of the Eurasian continent. In contrast, in the Yarlung Zangbo River Basin (YB), inner TP (ITP), and the source area of three eastern rivers (TER, including the Nujiang River, Lancang River, and Yangtze River), the moisture sources extended both westward and southward, but mainly southward along the ISM. In winter and spring, all of the sub-basins were dominated by western moisture sources. In summer, the western sources migrated northward with the zonal movement of the westerlies, and simultaneously the southern sources of the YB, ITP, and TER expanded largely toward the Indian Ocean along the ISM. In autumn, the moisture sources of the UI, UT, and QB shrank to the western sources, and the moisture sources of the YB, ITP, and TER shrank to the central-southern TP and the Indian subcontinent. By quantifying the moisture contributions from multiple sources, we found that the terrestrial moisture dominated in all of the sub-basins, particularly in the UT and QB (62–73%). The oceanic contributions were relatively high in the UI (38–42%) and YB (38–41%). In winter, evaporation from the large western water bodies (such as the Mediterranean, Red Sea, and Persian Gulf) was significantly higher than that from the continental areas. This contributed to the peak (valley) values of the oceanic (terrestrial) moisture contributions to all of the sub-basins. In summer, the terrestrial moisture contributions to the UI, UT, and QB reached their annual maximum, but the abundant oceanic moisture transported by the ISM restrained the appearance of land source contribution peaks in the YB, ITP, and TER, resulting in almost equal moisture contributions in the YB from the ocean and land. [ABSTRACT FROM AUTHOR]

Climate change can give rise to significant changes in the intensity and frequency of extreme events. In the present study, extreme wave events off the central-eastern coast of the Red Sea, near the city of Jeddah, were investigated using a 39-year wave hindcast generated using WaveWatch III configured at a 3.3 km resolution forced with ERA5 reanalysis winds. The validated model outputs were used to derive the annual and seasonal climatology for the region at a few selected locations off the Jeddah coast. The study revealed robust temporal and spatial variability in the region, considering the influence of both northern and southern Red Sea waves that meet at the convergent zone. Generalized Pareto Distribution (GPD) and Generalized Extreme Value (GEV) were two models used for the estimation of extreme wave analysis in the study region. The extreme significant wave heights were estimated for 10, 25, 50, and 100-year return periods. For offshore locations, the estimated return periods using the GPD method were 3.27, 3.44, and 3.38 m, respectively. GPD with the POT method was the more suitable approach, as it produced reduced bias and RMSE. At all locations, linear trends show an increase during the summer, winter, and pre-summer periods. No significant increase in the Hs trend was observed at the selected locations near and off the coast. However, the decrease in trend observed at all locations during the pre-winter period was noticeable for the 99th percentile Hs. [ABSTRACT FROM AUTHOR]

Heinrich-type ice-sheet surges are one of the dominant signals of glacial climate variability. They are characterised as abrupt, quasi-periodic episodes of ice-sheet instabilities during which large amounts of ice are discharged from ice sheets into the ocean. The occurence of ice-sheet surges strongly influences the global climate evolution by altering the ocean circulation through the addition of freshwater and the atmospheric circulation through changes in ice-sheet height. The mechanisms controlling the timing and occurence of Heinrich-type ice-sheet surges remain poorly constrained to this day. Here, we use a coupled ice sheet-solid earth model to identify and quantify the importance of boundary forcing for the surge cycle length of Heinrich-type ice-sheet surges for two prominent ice streams of the Laurentide ice sheet - the land-terminating Mackenzie ice stream and the marine-terminating Hudson ice stream. We show that surface mass balance perturbations have the largest effect on the surge cycle length. Pertubations to the ice surface temperature and geothermal heatflux also influence the surge cycle length, but to a lesser degree. Ocean and sea-level forcing as well as different frequencies of the same forcing have a negligible effect on the surge cycle length. The simulations also highlight that only a certain parameter space exists under which ice-sheet oscillations can be maintained. Transitioning from an oscillatory state to a persistent ice streaming state, can result in an ice volume loss of up to 26% for the respective ice stream drainage basin under otherwise constant climate conditions. We show that Mackenzie ice stream is susceptible to undergoing such a transition in response to all tested positive climate perturbations. This underlines the potential of the Mackenzie region to have contributed to prominent abrupt climate change events of the last deglaciation. [ABSTRACT FROM AUTHOR]

The Himalayan glaciers significantly contribute to the largest river systems like the Indus, Ganga, and the Brahmaputra. The change in glacial area and mass can affect the mountain community and people living in the Indo-Gangetic plain. The present study adopted the geodetic method to estimate the elevation change and mass budget of 61 glaciers in the Alaknanda Basin, using the satellite data of Cartosat-1 (2011, 2014, 2017) and SRTM (2000). Besides, the DEM of 1962 (SOI Toposheet) and 2000 (SRTM) is used to estimate the mass budget of Satopanth (SPG) and Bhagirath Kharak glaciers (BKG). The field debris thickness of SPG (2015-2017) is compared with the elevation change (2000-2017). Further, we have compared the mass loss of the glaciers with their volume. The results suggest the sustained mass loss of 1.85 ± 0.10 Gt out of 33.9 ± 8.8 Gt for 61 glaciers in the basin from 2000-2017. The mass loss of SPG and BKG during 2000-2017 is 0.20 ± 0.02 Gt and 0.24 ± 0.03 Gt, whereas from 1962 to 2000, is 0.083 ± 0.03 Gt and 0.091 ± 0.04 Gt, respectively. The analysis facilitates a better understanding of glacier mass changes in the Alaknanda basin on a multi-decadal scale. [ABSTRACT FROM AUTHOR]

The warming of the Arctic climate is well documented, but the mechanisms of Arctic amplification are still not fully understood. Thus, monitoring of glaciological and meteorological variables and the environmental response to accelerated climate warming must be continued and developed in Svalbard. Long-term meteorological observations carried out in situ on glaciers in conjunction with glaciological monitoring are rare in the Arctic and significantly expand our knowledge about processes in the polar environment. This study presents glaciological and meteorological data collected for 2009–2020 in southern Spitsbergen (Werenskioldbreen). The meteorological data are composed of air temperature, relative humidity, wind speed, short-wave and long-wave upwelling and downwelling radiation on 10 min, hourly and daily resolution (2009–2020). The snow dataset includes 49 data records from 2009 to 2019 with the snow depth, snow bulk density and snow water equivalent data. The glaciological data consist of seasonal and annual surface mass balance measurements (point and glacier-wide) for 2009–2020. The paper also includes modelling of the daily glacier surface ablation (2009–2020) based on the presented data. The datasets are expected to serve as local forcing data in hydrological and glaciological models as well as validation of calibration of remote sensing products. The datasets are available from the Polish Polar Database (https://ppdb.us.edu.pl/ , last access: 24 May 2022) and Zenodo (10.5281/zenodo.6528321, Ignatiuk, 2021a; 10.5281/zenodo.5792168, Ignatiuk, 2021b). [ABSTRACT FROM AUTHOR]

Most studies of sea level budget only indicate the stationary causes for the global mean sea level (GMSL) rise over the course of a time span of interest, providing limited information on temporary changes in the GMSL budget. In this contribution, we present an instantaneous budget of the GMSL for the period of 2003–2015, which offers new insights on the time evolution of the GMSL budget. We use a space-state model to compute the instantaneous rates of GMSL and their contributing sources (barystatic and steric contributions), to investigate the causes of the GMSL instantaneous budget, which accounts for and quantifies low-frequency variations in GMSL rise. Combining the barystatic GMSL instantaneous rates (estimated from satellite gravimetry) along with a particular choice of steric GMSL instantaneous rates (inferred from an Argo product) achieves closure of the GMSL instantaneous budget with a standard deviation of 0.4 mm yr−1. We find that the barystatic GMSL rate is primarily responsible for the striking fluctuations in the GMSL instantaneous rates between 2009 and 2015. For example, over only 20 months (July 2010 to February 2012), the GMSL (barystatic) rate increases from 0.32 (0.71) to 6.12 (4.55) mm yr−1. These strong fluctuations mainly result from hydrology and mountain glacier mass variations rather than mass loss in ice sheet, for instance, Australia slowed ∼1.2 mm yr−1 equivalent contribution to GMSL rise over the year 2010, which is approximately four times the linear rate of Antarctica mass loss. [ABSTRACT FROM AUTHOR]

Ice flow lines are the most dominant feature of ice sheet surfaces. Accurate delineation of basins is a prerequisite for mass balance. We therefore propose a new weight balance-based approach to extract the present most comprehensive ice flow lines and then re-delineate the Antarctic basin on this basis. In our approach, we define three impact factors to represent directional accuracy, smoothness, and physical character. Following this, a weight balance-based method is proposed, in which those factors are integrated via weights, to determine the pointing pixels (points or subpixels of the ice flow line). After that, the ice flow lines are continuously tracked. Finally, Antarctic basins were re-delineated based on it. The results indicate that the derived ice flow lines exhibit a rational ice flow pattern against the DEM and the proposed method remarkably improves the performance of results. Furthermore, compared with the Antarctic IMBIE (Ice sheet Mass Balance Inter-Comparison Exercise) basins, the redivided basins exhibit slight diversity, with differences in area and length of less than 11% and a directional accuracy of less than 1° (covering more than 90% of area). As a result, the redivided basins are beneficial to the investigation of the in-depth mechanism of ice shelf calving and mass balance in the Antarctic. [ABSTRACT FROM AUTHOR]

The Indian and East Asian summer monsoons shape the melt and accumulation patterns of glaciers in High Mountain Asia in complex ways due to the interaction of persistent cloud cover, large temperature ranges, high atmospheric water content and high precipitation rates. Glacier energy- and mass-balance modelling using in situ measurements offers insights into the ways in which surface processes are shaped by climatic regimes. In this study, we use a full energy- and mass-balance model and seven on-glacier automatic weather station datasets from different parts of the Central and Eastern Himalaya to investigate how monsoon conditions influence the glacier surface energy and mass balance. In particular, we look at how debris-covered and debris-free glaciers respond differently to monsoonal conditions. The radiation budget primarily controls the melt of clean-ice glaciers, but turbulent fluxes play an important role in modulating the melt energy on debris-covered glaciers. The sensible heat flux decreases during core monsoon, but the latent heat flux cools the surface due to evaporation of liquid water. This interplay of radiative and turbulent fluxes causes debris-covered glacier melt rates to stay almost constant through the different phases of the monsoon. Ice melt under thin debris, on the other hand, is amplified by both the dark surface and the turbulent fluxes, which intensify melt during monsoon through surface heating and condensation. Pre-monsoon snow cover can considerably delay melt onset and have a strong impact on the seasonal mass balance. Intermittent monsoon snow cover lowers the melt rates at high elevation. This work is fundamental to the understanding of the present and future Himalayan cryosphere and water budget, while informing and motivating further glacier- and catchment-scale research using process-based models. [ABSTRACT FROM AUTHOR]

In this study, an image segmentation algorithm ("OTSU") is applied for differentiation of snow/ice regions followed by interpretation of snowlines and estimation of mass budget of glaciers in Chandra basin, Western Himalaya, India between 2014 and 2020. The observations strongly suggest that the OTSU method can be used to differentiate the snow and ice regions on a glacier accurately from any satellite image, irrespective of the sensor characteristics. Also, this method suits well to delineate the snowlines for large sample of glaciers, other than the manual interpretation and semi-automated methods. The estimates of mass budget of the glaciers are observed varying from − 1.20 ± 0.51 m w.e to almost 0.64 ± 0.51 m w.e, with a total loss of − 61.91 ± 6.70 m w.e of ice mass at basin scale during the observation period. Based on this study, it is highly recommended the application of OTSU method for the differentiation of snow/ice zones of glaciers and snowline demarcation at a large spatial scale in the harsh weather rugged terrain of the Western Himalaya. [ABSTRACT FROM AUTHOR]

Meltwater from the cryosphere contributes a significant fraction of the freshwater resources in the countries receiving water from the Third Pole. Within the ESA-MOST Dragon 4 project, we addressed in particular changes of glaciers and proglacial lakes and their interaction. In addition, we investigated rock glaciers in permafrost environments. Here, we focus on the detailed investigations which have been performed in the Poiqu River Basin, central Himalaya. We used in particular multi-temporal stereo satellite imagery, including high-resolution 1960/70s Corona and Hexagon spy images and contemporary Pleiades data. Sentinel-2 data was applied to assess the glacier flow. The results reveal that glacier mass loss continuously increased with a mass budget of −0.42 ± 0.11 m w.e.a−1 for the period 2004–2018. The mass loss has been primarily driven by an increase in summer temperature and is further accelerated by proglacial lakes, which have become abundant. The glacial lake area more than doubled between 1964 and 2017. The termini of glaciers that flow into lakes moved on average twice as fast as glaciers terminating on land, indicating that dynamical thinning plays an important role. Rock glaciers are abundant, covering approximately 21 km2, which was more than 10% of the glacier area (approximately 190 km2) in 2015. With ongoing glacier wastage, rock glaciers can become an increasingly important water resource. [ABSTRACT FROM AUTHOR]

Under current global warming, most glaciers on the Tibetan Plateau have shown significant mass loss during 2000–2019. However, the average glacier mass balance in the western Kunlun Mountains (WKM) was positive during this period. The causes of these opposing average status and the temporal glacier mass changes over the last several decades in the WKM continue to be the subject of active debate. The long‐term mass balance of the Guliya Ice Cap (Guliya) in the WKM during 1970–2019 was reconstructed using an energy and mass balance model and calibrated ERA5 data, which was calibrated and validated by in situ measurements and geodetic mass balances. Guliya showed a positive mean mass balance during 2000–2019 because annual snowfall was larger than low ablation‐season meltwater caused by low air temperature (Ta). At interannual scales, annual mass balances were equally controlled by ablation‐season precipitation and Ta during 1970–2019. From 1970s–1990s to 1990s–2010s, most Tibetan glaciers showed decreased mass balance due to increased ablation season Ta, while the WKM glaciers experienced increased mass balance due to increased ablation‐season precipitation related to changes in the Silk Road Pattern. However, during 2000–2019, the annual mass balance of Guliya followed a decreasing trend due to increasing ablation‐season Ta. The positive mass balance of the WKM glaciers will cease under future warming due to annual snowfall decreasing below ablation‐season meltwater. These changes will threaten lives and livelihoods in the Tarim Basin, whilst also jeopardizing ice core‐derived climate histories from the WKM glaciers. Key Points: Low ablation‐season temperature caused low melt and a high proportion of snowfall, and led to glacier anomaly during 2000–2019 in the western Kunlun Mountains (WKM)Guliya experienced increased mass balance from 1970–1999 to 2000–2019 due to increased ablation‐season precipitation related to changed Silk Road PatternWarming caused the decreased mass balance of Guliya during 2000–2019 and will lead to future glacier mass loss in the WKM [ABSTRACT FROM AUTHOR]

The application of a distributed energy balance model over nine years at an hourly time step to a 20 × 20 m grid cell over Glacier Zongo (Bolivia, 16°S) enabled assessment of the climate factors that control the interseasonal and interannual variability of its surface mass balance. The model was validated by comparing the measured and simulated discharge at the outlet, albedo at the Automatic Weather Station, surface state and annual mass balance both glacier‐wide and as a function of altitude. Analysis of the mean monthly energy fluxes highlighted the importance of the meteorological conditions over October and November on the variability of the annual surface mass balance. Two sensitivity analyses are presented, one of the distribution of precipitation over time which maintains a physical coherence between the different meteorological variables and one of the impact of prolonged periods of intense cloud radiative forcing on the surface mass balance. The distribution of precipitation events over time and their associated amounts are the main drivers of the interannual variability of the surface mass balance via an albedo feedback effect. Additionally, prolonged periods of negative cloud radiative forcing, specifically over the month of November, notably reduce the melt rate. Plain Language Summary: This study aimed at identifying the meteorological variables which control the seasonal and annual melt rates of a tropical glacier in Bolivia considering nine years of measurements at the hourly timescale. The analysis of the energy fluxes at the weather station has shown that the period between the austral winter and summer is the period during which most melt can be generated making it key in defining the annual melt rates. The analysis of the impact of measured meteorological variables on the melt rate has shown that it is the solar energy that controls most of it. The amount of solar energy available for melt is defined by the state of the glacier surface (snow, ice, debris) which controls the amount of reflected energy. In this context, the frequency of the snowfall events plays a key role in controlling the melt as frequent events imply a whiter glacier which is able to reflect most of the incoming solar energy. Similarly, because clouds can block large portions of solar energy, sustained cloud periods can play an important role in reducing the melt rate. Key Points: Seasons over Zongo Glacier can be identified using the distribution of the cloud radiative forcingOctober and November play a strong control on the interannual surface mass balance variability of Zongo GlacierDistribution of the precipitation events in time is key in controlling the melt rate [ABSTRACT FROM AUTHOR]

Developing a long‐term understanding of the cryosphere is important in the study of past climatic change. Here we used a nested approach combining diverse instrumental (monthly meteorological data from four weather stations, as well as gridded data) and proxy data (based on blue intensity measurements from local tree ring records) to create a reconstruction of past summer temperature for the central Jotunheimen area in southern Norway. This record was then used to reconstruct annual glacier mass balance from 1962, the start of the yearly measurements, back to 1722, immediately prior to the regional Little Ice Age maximum. Our reconstruction of the 'average' Jotunheimen cumulative glacier mass balance is based on three representative glaciers (Storbreen, Hellstugubreen and Gråsubreen) that were synthesized into one composite record which we term 'Gjennomsnittsbreen' ('mean glacier' in Norwegian) to filter out localized controls on the behaviour of individual glaciers. While not ignoring the role of precipitation on glacier mass balance, our reconstruction demonstrates that glaciers in this region exhibit a strong summer temperature control and appear to have been declining more or less continuously since the mid‐18th century. However, it also shows that this long‐term trend of overall retreat in Jotunheimen is punctuated by relatively short‐lived periods of neutral or occasionally positive glacier mass balance, signifying periods of stillstand or small‐scale glacier advance. These periods or 'events' in our reconstruction were compared with an independent record of 12 moraine‐building events developed using lichenometry. A minimum of 10 of the moraine‐building events identifiable in our reconstruction were also identifiable in the lichenometric data which affords confidence in the performance of our interrogative model. A critical implication of this successful glacier mass balance reconstruction based on just summer temperature is that for Jotunheimen – in contrast to Norwegian maritime glaciers further to the west – there is no need (as was proposed in some previous studies) to invoke large, prolonged increases in winter snowfall to explain glacier advances, not even for events such as the Little Ice Age. [ABSTRACT FROM AUTHOR]

Most studies attribute the glacier mass balance within High Mountain Asia (HMA) to climate change, ignoring the influence of its complex terrain. Knowledge of the influence of this complex terrain is crucial for understanding the spatial variability in its mass balance. However, there is a lack of any systematic assessment of this influence across HMA. Therefore, in this study, we used the glacier outlines and raster data (SRTM DEM, slope and aspect) to calculate the topographic shading of all 97,965 glaciers within HMA during the ablation period, which is regarded as a major index of the influence of complex terrain on the mass balance. The results showed that 27.19% of HMA glacier area was subjected to topographic shading, and regional differences were significant with respect to both their altitudinal and spatial distributions. The topographic shading contributed to the protection of the smallest glaciers from solar illumination. Furthermore, we found a significant correlation between the topographic shading and mass balance in these small north-facing glaciers. However, these small glaciers were most prevalent in the north-facing orientation, especially in West Kunlun, East Kunlun, Inner Tibet Plateau and Qilian Shan, where shading was found to increase with decreases in the glacier area. This indicates that complex terrain can affect the spatial distribution of the mass balance by altering the solar illumination pattern. [ABSTRACT FROM AUTHOR]

The Antarctic Peninsula has become an increasingly important component of the Antarctic Ice Sheet mass budget over the last 2 decades, with mass losses generally increasing. However, due to the challenges presented by the topography and geometry of the region, there remain large variations in mass balance estimates from conventional approaches and in assessing the relative contribution of individual ice sheet processes. Here, we use a regionally optimized Bayesian hierarchical model joint inversion approach that combines data from multiple altimetry studies (ENVISAT, ICESat, CryoSat-2 swath), gravimetry (GRACE and GRACE-FO), and localized DEM differencing observations to solve for annual mass trends and their attribution to individual driving processes for the period 2003–2019. This is first time that such localized observations have been assimilated directly to estimate mass balance as part of a wider-scale regional assessment. The region experienced a mass imbalance rate of -19±1.1 Gt yr -1 between 2003 and 2019, predominantly driven by accelerations in ice dynamic mass losses in the first decade and sustained thereafter. Inter-annual variability is driven by surface processes, particularly in 2016 due to increased precipitation driven by an extreme El Niño, which temporarily returned the sector back to a state of positive mass balance. In the West Palmer Land and the English Coast regions, surface processes are a greater contributor to mass loss than ice dynamics in the early part of the 2010s. Our results show good agreement with conventional and other combination approaches, improving confidence in the robustness of mass trend estimates, and in turn, understanding of the region's response to changes in external forcing. [ABSTRACT FROM AUTHOR]

Sampling campaigns were conducted at the industrial bauxite wash circuit of the Juruti Bauxite Mine in Pará, Brazil. The beneficiation circuit consisted of crushing, scrubber washing, wet screening, hydrocyclone classification, and filtration. Considering laboratory processing of samples and statistical analyses of historical operation databases, mass balances were obtained. Integrated analyses of historical databases, mass balances and operating parameters enabled the calculation of performance indices, which constitute the basis for the identification and hierarchy of the bottlenecks in terms of washability efficiency; that is, removal of the fraction below 0.037 mm. Typically, the focus of bauxite ore concentration in the Amazon region is the removal of the 0.037 mm fraction in the concentrate streams via disaggregation and mud washing. Consolidated mass balances indicated consistent values based on the size of the sample particles and percentage of solids, as well as the values obtained from the integrated information systems of the plant; this consistency indicated the stability and representativeness of the process conditions during the sampling campaigns. The base case of the Juruti plant operation, from which the performance indices that allowed the quantification of the efficiency of each process step was calculated, was obtained as a result. [ABSTRACT FROM AUTHOR]

In the context of global warming, the melting of glaciers in the Tien Shan Mountains as the important "solid reservoir" in the arid area of Central Asia is accelerating in recent decades, leading to profound changes in regional water resources. Based on the simulated glaciological data from the Python Glacier Evolution Model (PyGEM) and the measured glaciological data from the World Glacier Monitoring Service (WGMS), this paper analyzed the applicability of simulated data, the changes in glacier mass balance, and the responses of the glacier to climate change and its impacts on glacier runoff in the Tien Shan Mountains. The results show that (1) the PyGEM simulation dataset is in good agreement with the measurements, which can effectively reproduce the change in the glacier mass balance in the Tien Shan Mountains glaciers and is suitable for studying the regional scale glacier change. (2) From 1980 to 2016, the decadal average mass balance change rate of glaciers in the Tien Shan Mountains was −0.012 m w.e. yr−1. The regional mass balance showed an overall negative increasing trend (the area with increasingly negative accounted for 80.13% of the entire area), with a positive increase that only occurred in the West Tien Shan Mountains and western North Tien Shan Mountains (19.87%). (3) The correlation between the temperature and mass balance is much higher than that between the precipitation and mass balance. Temperature dominates the change and development of regional glaciers. The increase in negative glacier mass balance that was observed in the study area is mainly affected by the rising temperature, the decreasing solid precipitation in the accumulation period, and the rapid melting in the ablation period. (4) The glacier runoff in the six representative rivers showed an increasing trend. The contribution rate of glacier runoff to river runoff changed significantly after 2000 but differed among rivers. Overall, the larger the glacier area in the source region is, the greater the contribution rate of glacier runoff is, and the more the contribution rate continuously increases or fluctuates; otherwise, the contribution rate keeps declining, which means the runoff peak may have passed and future runoff may decrease. [ABSTRACT FROM AUTHOR]

In this study, we compare equilibrium-line altitudes (ELAs) calculated using the area–altitude balance ratio (AABR) and the accumulation–area ratio (AAR) methods, with measured ELAs derived from direct field observations. We utilise a GIS toolbox to calculate the ELA for 64 extant glaciers by applying the AABR and AAR methods to DEMs and polygons of their geometry. The calculated ELAs (c-ELAs) are then compared to measured zero-net balance ELAs (znb-ELAs) obtained from mass-balance time series held by the WGMS for the same glaciers. The correlation between znb-ELAs and AABR (1.56)/AAR (0.58) c-ELAs is very strong, with an r2 = 0.99. The smallest median difference between znb-ELAs and c-ELAs (i.e. 65.5 m) is obtained when a globally representative AABR of 1.56 is used. When applied to palaeoglacier-climate applications, this difference translates to ~0.42°C, well within the uncertainty of palaeotemperature proxies used to determine mean summer temperature at the ELA. The more widely used mean AABR of 1.75 is shown to be statistically invalid due to the skewness of the dataset. On this basis, when calculating glacier ELAs, we recommend the use of a global AABR value of 1.56. [ABSTRACT FROM AUTHOR]

In 2015, the Olympic Mountains contained 255 glaciers and perennial snowfields totaling 25.34 ± 0.27 km2, half of the area in 1900, and about 0.75 ± 0.19 km3 of ice. Since 1980, glaciers shrank at a rate of −0.59 km2 yr−1 during which time 35 glaciers and 16 perennial snowfields disappeared. Area changes of Blue Glacier, the largest glacier in the study region, was a good proxy for glacier change of the entire region. Modeled glacier mass balance, based on monthly air temperature and precipitation, correlates with glacier area change. The mass balance is highly sensitive to changes in air temperature rather than precipitation, typical of maritime glaciers. In addition to increasing summer melt, warmer winter temperatures changed the phase of precipitation from snow to rain, reducing snow accumulation. Changes in glacier mass balance are highly correlated with the Pacific North American index, a proxy for atmospheric circulation patterns and controls air temperatures along the Pacific Coast of North America. Regime shifts of sea surface temperatures in the North Pacific, reflected in the Pacific Decadal Oscillation (PDO), trigger shifts in the trend of glacier mass balance. Negative ("cool") phases of the PDO are associated with glacier stability or slight mass gain whereas positive ("warm") phases are associated with mass loss and glacier retreat. Over the past century the overall retreat is due to warming air temperatures, +0.7°C in winter and +0.3°C in summer. The glaciers in the Olympic Mountains are expected to largely disappear by 2070. Plain Language Summary: The Olympic Mountains in Washington State contain 255 glaciers and perennial snowfields as of 2015. Their total area is 25.34 ± 0.27 km2, about half of the ice‐covered area in 1900. Since 1980, yearly glacier area loss averaged −0.59 km2 yr−1 and 35 glaciers and 16 perennial snowfields have disappeared. Warming winter temperatures are particularly important to the glacier shrinkage. Because the Olympic Mountains are close to the Pacific Ocean winters are mild and air temperatures are close to freezing. Warming winters causes more precipitation to fall as rain rather than snow, which does not nourish the glaciers. With warmer summers causing more ice melt and warmer winters causing less snowfall, the glaciers are being hammered in both seasons. Local air temperatures, and therefore the glaciers, are strongly affected by surface temperature of the nearby ocean. The future of these glaciers is dire, modeling using climate projections suggests that the glaciers will largely disappear by 2070. Key Points: The glaciers of the Olympus Peninsula are shrinking rapidly, losing half of its ice‐covered area since 1900Warming air temperatures are causing glacier loss; warming winter temperatures change the phase of the precipitation from snow to rainModeling suggests the glaciers will largely disappear by 2070 [ABSTRACT FROM AUTHOR]

Glacier change monitoring provides a significant understanding of glacier health and its influence on freshwater availability. Therefore, we have utilized remotely sensed data to estimate the glacier characteristics, mass balance, and volume change during 2013–2019 over the Sutri Dhaka and Batal glaciers, Chandra basin, western Himalayas. The glacier feature classification and shifting in isoline were mapped on a spatio-temporal scale. Furthermore, the surface velocity was measured using Coregistration of Optically Sensed Images and Correlation (COSI-Corr) and then used for estimating the ice thickness. The estimated velocity was compared with the stake observations and National Aeronautics and Space Administration (NASA)- Inter-Mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) data. Further, the glaciers' geodetic mass balance and volume change were calculated, indicating an average value of −0.03 ± 0.5, −0.34 ± 0.40 and −0.13 ± 0.14 m water equivalent (w.e.) year−1 during 2000–2009, 2009–2020, and 2000–2020, respectively. This multidimensional analysis of the glaciers is critical, as the meltwater from both glaciers contributes to the Chandra basin and also influences the local ecosystem. [ABSTRACT FROM AUTHOR]

Since 2012, seven perennial snow patches in the northern Japanese Alps have been determined to be very small glaciers (VSGs: <0.5 km 2). However, it had not been determined how such glaciers could be maintained in such a warm climate. In this study, we calculate the annual mass balance, accumulation depth, and ablation depth of five of these VSGs, covering 2015–2019 for four of them (2017–2019 for the fifth) using multi-period digital surface models (DSMs) based on structure-from-motion–multi-view-stereo (SfM–MVS) technology and images taken from a small airplane. The results indicate that, due to snow acquired from avalanches and snowdrifts, these VSGs are maintained by an accumulation in winter that is more than double that from the snowfall, thereby exceeding the ablation in summer. Therefore, we classify them as topographically controlled VSGs. We find very small yearly fluctuations in their ablation depth; however, their annual mass balance and accumulation depth have large yearly fluctuations. The annual mass balance, which mainly depends on the accumulation depth, showed accumulation throughout each glacier during heavy snow years and ablation throughout each glacier during light snow years. This characteristic differs from the upper accumulation area and lower ablation area that exists on most glaciers. These VSGs lack a positive annual mass balance gradient, which suggests that they are not divided by a distinct glacier equilibrium line altitude (ELA) into an upstream accumulation area and a downstream ablation area. Moreover, compared to other glaciers worldwide, we find the mass balance amplitude of VSGs in the northern Japanese Alps to be the highest measured to date. [ABSTRACT FROM AUTHOR]

Blast furnace (BF) is the most used equipment for production of iron in the world. It is charged mainly with metallurgical coke and ferrous materials. When descending inside the BF, iron‐bearing materials start reducing and melting with other burden materials. This melting leads to the formation of so‐called primary slags from which the final slag is formed as materials descend inside the furnace. Each charge material has a unique effect on the total composition of the BF slag. Herein, the parts of the slag, which originate from ash of metallurgical coke and pulverized coal, and changes in the final slag compositions and properties are focused on. The global trend is to decrease the use of fossil‐based carbon by replacing it with bio‐based coal. Ash from coke and pulverized coal eventually dissolve in the final slag, affecting its properties. The purpose herein is to evaluate how BF slag composition changes when fossil‐based coke is replaced with biocoke and pulverized coal is replaced with charcoal. Based on mass balance calculations, these replacements have both increasing and decreasing effects on solidus and liquidus temperatures, viscosity, and CaO/SiO2 and MgO/Al2O3 ratios depending on the used replacement materials. [ABSTRACT FROM AUTHOR]

The Himalayan cryosphere system is a major source of freshwater supply for the Indian subcontinent. The rivers originating from the Himalaya are strongly influenced by the behaviour of glaciers depending upon the regional climatic variables. Therefore, understanding the mass budget of glaciers is important. In the present study, we discuss the hydrological mass balance of the largest Siachen glacier in the Karakoram range. The computations of runoff and other parameters on such a large glacier are challenging due to data scarcity, difficult accessibility and complex topography of the region. The snowmelt runoff model (SRM) coupled with in-situ and remotely sensed information was used to simulate the glacier runoff for the past three decades (1986–2018). The accumulation in the form of snowfall and ablation in the form of snowmelt and evaporation were used as inputs for the estimation of hydrological mass balance. The SRM has well estimated the discharge of Siachen glacier with the coefficient of determination (R2) 0.92 and average volume difference (Dv) 4.4% for the validation period. The study revealed that the Siachen glacier experienced few marginally mass gain episodes before 2000 but after that, a rapid and continuous mass loss has been observed. The average mass balance during the past three decades was found to be −0.11 ± 0.24 m w.e./year. This suggests that glaciers of East Karakoram have started losing mass; still, it is not as significant as generally observed in other parts of the Hindu Kush Himalaya. [ABSTRACT FROM AUTHOR]

Earth system models account for seasonal snow cover, but many do not accommodate the deeper snowpack on ice sheets (aka firn) that slowly transforms to ice under accumulating snowfall. To accommodate and resolve firn depths of up to 60 m in the Energy Exascale Earth System Model's land surface model (ELM), we add 11 layers to its snowpack and evaluate three dry snow compaction equations in multi‐century simulations. After comparing results from ELM simulations (forced with atmospheric reanalysis) with empirical data, we find that implementing into ELM a two‐stage firn densification model produces more accurate dry firn densities at intermediate depths of 20–60 m. Compared to modeling firn using the equations in the (12 layer) Community Land Model (version 5), switching to the two‐stage firn densification model (with 16 layers) significantly decreases root‐mean‐square errors in upper 60 m dry firn densities by an average of 41 kg m−3 (31%). Simulations with three different firn density parameterizations show that the two‐stage firn densification model should be used for applications that prioritize accurate upper 60 m firn air content (FAC) in regions where the mean annual surface temperature is greater than roughly −31°C. Because snow metamorphism, firn density, and FAC are major components in modeling ice sheet surface albedo, melt water retention, and climatic mass balance, these developments advance broader efforts to simulate the response of land ice to atmospheric forcing in Earth system models. Plain Language Summary: Massive ice sheets cover Earth's largest island (Greenland) and the Antarctic continent. A large fraction of their surfaces consists of multi‐year snow, known as firn, which goes through the process of densification after falling from the atmosphere. Until now this fundamental process in glaciology has yet to be accounted for in the U.S. Department of Energy's Earth System Model (E3SM). Here, we enhance E3SM's snowpack model to accommodate greater firn depths on ice sheets. Our results demonstrate a new capability in an Earth system model, that is, calculating firn density as deep as 60 m below the surface. Our developments in E3SM combine both seasonal snow and firn processes to advance broader efforts toward simulating ice sheet evolution and sea level rise in Earth system models. Key Points: We intercompare three snow density parameterizations and their effects on firn simulated in Energy Exascale Earth System Model's land model (ELM)Incorporating a two‐stage firn densification model into ELM improves densities at depths of 20–60 mApplied to Greenland and Antarctica, improving 20–60 m depth dry firn density decreases firn air content by more than 20% [ABSTRACT FROM AUTHOR]

Continuous and robust measurements are needed for the high end-product quality and efficient and eco-friendly process in paperboard manufacturing. As the online measurements enable the optimization of the manufacturing process making it more cost effective and environmentally friendly, these measurements must be validated carefully and continuously. This paper presents the development of a mass-balance based soft sensor for online estimation of a two-ply paperboard ash content. The developed soft sensor considers the basis weight, moisture and fiber measurements to derive the ash content of the paperboard at the reel. The development of the soft sensor was success (Mean Absolute Percentage Error was 11.80) and during the long-term simulation with measured data, this robust online estimator showed the level and changes in ash content accurately, enabling also the continuous validation of the hardware sensor. [ABSTRACT FROM AUTHOR]

Purpose: Bioremediation experiments of polycyclic aromatic hydrocarbon (PAHs) using ryegrass (Lolium perenne), a turfgrass in urban landscapes, were carried out aiming to explore the ryegrass-assisted degradation in an actual PAH-contaminated urban soil and the phytotransformation pathways of PAHs within plants. Methods: Dynamics of plant-assisted degradation of 15 PAHs in pot soils were recorded over 100-day cultivation, and at the end, the accumulation of PAHs in ryegrass was investigated. Ryegrass with phenanthrene exposure was cultured hydroponically to investigate the phytotransformation intermediates using gas chromatography–mass spectrometry and ultra-performance liquid chromatography coupled to high-resolution mass spectrometry. Results: Overall, dissipation of PAHs in soils exhibited an initial fast and subsequent slow degradation pattern. Eventually, on average, 55.7% and 47.1% of ∑ PAHs were removed in the planted and unplanted soils, respectively, with the high-molecular-weight PAHs highly eliminated particularly. Plant growth resulted in 4.8–11.1% more ∑ PAHs removed from soil compared to the plant-free controls. The PAHs all exhibited the bioconcentration and translocation factors below 1. The mass balance calculation showed that plant uptake accounted for < 1% of the dissipation increase while plant-promoted microbial biodegradation made the dominant contribution. A total of 7 metabolites were tentatively identified based on which possible transformation pathways were proposed. Conclusion: The results indicated that ryegrass may act as a metabolic sink for aqueous PAHs while microbes play a dominant role in soil PAH dissipation via biodegradation. The results may pave the path for a scientific, safe, and effective implementation of landscape configuration to ameliorate urban soil pollution. [ABSTRACT FROM AUTHOR]