scholarly journals Satellite-observed monthly glacier and snow mass changes in southeast Tibet: implication for substantial meltwater contribution to the Brahmaputra

2020 ◽  
Vol 14 (7) ◽  
pp. 2267-2281 ◽  
Author(s):  
Shuang Yi ◽  
Chunqiao Song ◽  
Kosuke Heki ◽  
Shichang Kang ◽  
Qiuyu Wang ◽  
...  
Keyword(s):  
Mass Balance ◽  
Seasonal Variations ◽  
Summer Precipitation ◽  
High Sensitivity ◽  
Tibet Plateau ◽  
High Asia ◽  
Terrestrial Water ◽  
Long Term Trend ◽  
Snow Mass

Abstract. High-Asia glaciers have been observed to be retreating the fastest in the southeastern Tibet Plateau (SETP), where vast numbers of glaciers and amounts of snow feed the streamflow of the Brahmaputra, a transboundary river linking the world's two most populous countries, China and India. However, the low temporal resolutions in previous observations of glacier and snow (GS) mass balance obscured the seasonal accumulation–ablation variations, and their modelling estimates were divergent. Here we use monthly satellite gravimetry observations from August 2002 to June 2017 to estimate GS mass variation in the SETP. We find that the “spring-accumulation-type” glaciers and snow in the SETP reach their maximum in May. This is in stark contrast to seasonal variations in terrestrial water storage, which is controlled by summer precipitation and reaches the maximum in August. These two seasonal variations are mutually orthogonal and can be easily separated in time-variable gravity observations. Our GS mass balance results show a long-term trend of -6.5±0.8 Gt yr−1 (or 0.67±0.08 m w.e. yr−1) and annual mass decreases ranging from −49.3 to −78.3 Gt with an average of -64.5±8.9 Gt in the SETP between August 2002 and June 2017. The contribution of summer meltwater to the Brahmaputra streamflow is estimated to be 51±9 Gt. This result could help to resolve previous divergent modelling estimates and underlines the importance of meltwater to the Brahmaputra streamflow. The high sensitivity between GS melting and temperature on both annual and monthly scales suggests that the Brahmaputra will suffer from not only changes in total annual discharge but also an earlier runoff peak due to ongoing global warming.

scholarly journals Substantial meltwater contribution to the Brahmaputra revealed by satellite gravimetry

2019 ◽  
Author(s):  
Shuang Yi ◽  
Chunqiao Song ◽  
Kosuke Heki ◽  
Shichang Kang ◽  
Qiuyu Wang ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Summer Precipitation ◽  
High Sensitivity ◽  
Tibet Plateau ◽  
Mass Variation ◽  
Satellite Gravimetry ◽  
Winter Snow ◽  
High Asia ◽  
Terrestrial Water ◽  
Annual Discharge

Abstract. High Asia glaciers were observed to be reducing the fastest in the southeastern Tibet Plateau (SETP), where vast amounts of glacier and snow (GS) feed the streamflow of the Brahmaputra, a transboundary river linking the world's two most populous countries China and India. However, the low temporal resolutions in previous studies obscured the seasonal accumulation/ablation variations, and their modelling estimates were divergent. Here we use monthly satellite gravimetry observations from August 2002 to June 2017 to estimate GS mass variation in the SETP. We find that the spring-accumulation type glaciers and winter snow in the SETP are the most abundant in May. This is in stark contrast to seasonal variations in terrestrial water storage, which reaches its maximum in August and is controlled by summer precipitation. These two seasonal variations are mutually orthogonal and can be easily separated in time-variable gravity observations. Our results show a summer meltwater contribution of 43 ± 8 Gt to the Brahmaputra. This value could help to resolve previous divergent modelling estimates and underlines the importance of meltwater to the Brahmaputra streamflow. The high sensitivity between GS melting and temperature on both annual and monthly scales suggests that the Brahmaputra will suffer from not only changes in total annual discharge, but also an earlier runoff peak due to the ongoing global warming.

scholarly journals The mass balance of McCall Glacier, Brooks Range, Alaska, U.S.A.; its regional relevance and implications for climate change in the Arctic

1998 ◽  
Vol 44 (147) ◽  
pp. 333-351 ◽  
Author(s):  
B.T. Rabus ◽  
K. A. Echelmeyer
Keyword(s):  
Mass Balance ◽  
The Arctic ◽  
Balance Model ◽  
Mass Balances ◽  
Arctic Alaska ◽  
Low Mass ◽  
Length Changes ◽  
Arctic Glacier ◽  
Long Term Trend

AbstractMcCall Glacier has the only long-term mass-balance record in Arctic-Alaska. Average annual balances over the periods 1958–72 and 1972–93 were –15 and –33cm, respectively; recent annual balances (1993–96) are about –60 cm, and the mass-balance gradient has increased. For an Arctic glacier, with its low mass-exchange rate, this marks a significant negative trend.Recently acquired elevation profiles of McCall Glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973. Most of these glaciers had average annual mass balances between –25 and –33 cm, while McCall Glacier averaged –28 cm for 1956–93, indicating that it is representative of the region. In contrast, changes in terminus position for the different glaciers vary markedly. Thus, mass-balance trends in this region cannot be estimated from fractional length changes at time-scales of a few decades.We developed a simple degree-day/accumulation mass-balance model for McCall Glacier. The model was tested using precipitation and radiosonde temperatures from weather stations at Inuvik, Canada, and Barrow, Kaktovik and Fairbanks, Alaska, and was calibrated with the measured balances. The Inuvik data reproduce all measured mass balances of McCall Glacier well and also reproduce the long-term trend towards more negative balances. Data from the other stations do not produce satisfactory model results. We speculate that the Arctic Front, oriented east–west in this region, causes the differences in model results.

scholarly journals Mass Balance of the Greenland Ice Sheet from GRACE and Surface Mass Balance Modelling

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1847 ◽  
Author(s):  
Fang Zou ◽  
Robert Tenzer ◽  
Hok Fok ◽  
Janet Nichol
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Rapid Decline ◽  
Surface Mass Balance ◽  
Discharge Data ◽  
Surface Mass ◽  
Term Trend ◽  
Long Term Trend

The Greenland Ice Sheet (GrIS) is losing mass at a rate that represents a major contribution to global sea-level rise in recent decades. In this study, we use the Gravity Recovery and Climate Experiment (GRACE) data to retrieve the time series variations of the GrIS from April 2002 to June 2017. We also estimate the mass balance from the RACMO2.3 and ice discharge data in order to obtain a comparative analysis and cross-validation. A detailed analysis of long-term trend and seasonal and inter-annual changes in the GrIS is implemented by GRACE and surface mass balance (SMB) modeling. The results indicate a decrease of −267.77 ± 8.68 Gt/yr of the GrIS over the 16-year period. There is a rapid decline from 2002 to 2008, which accelerated from 2009 to 2012 before declining relatively slowly from 2013 to 2017. The mass change inland is significantly smaller than that detected along coastal regions, especially in the southeastern, southwestern, and northwestern regions. The mass balance estimates from GRACE and SMB minus ice discharge (SMB-D) are very consistent. The ice discharge manifests itself mostly as a long-term trend, whereas seasonal mass variations are largely attributed to surface mass processes. The GrIS mass changes are mostly attributed to mass loss during summer. Summer mass changes are highly correlated with climate changes.

scholarly journals Seasonal Variations and Long-term Trend of Mineral Dust Aerosols over the Taiwan Region

2020 ◽  
Vol 20 ◽  
Author(s):  
Yanda Zhang ◽  
Yi-Jhen Cai ◽  
Fangqun Yu ◽  
Gan Luo ◽  
Charles C.K. Chou
Keyword(s):  
Seasonal Variations ◽  
Mineral Dust ◽  
Term Trend ◽  
Dust Aerosols ◽  
Long Term Trend ◽  
Taiwan Region ◽  
Mineral Dust Aerosols

scholarly journals Massive crop expansion threatens agriculture and water sustainability in Northwestern China

2021 ◽  
Author(s):  
Jiameng Lai ◽  
Yanan Li ◽  
Jianli Chen ◽  
Guo-Yue Niu ◽  
Peirong Lin ◽  
...  
Keyword(s):  
Anthropogenic Activities ◽  
Water Security ◽  
Initial Step ◽  
Northwestern China ◽  
Efficiency Enhancement ◽  
Agricultural Water Use ◽  
Glacier Melting ◽  
Terrestrial Water ◽  
Long Term Trend

Abstract Northwestern China (NWC) is among the major global hotspots undergoing massive terrestrial water storage (TWS) depletion. Yet driver(s) underlying such region-wide depletion remain controversial, i.e., warming-induced glacier-melting versus anthropogenic activities. Reconciling this controversy is the core initial step to guide policy-making for combating the dual challenges in agriculture production and water scarcity in the vastly dry NWC towards sustainable development. Utilizing diverse observations, we found persistent cropland expansion by >1.2×104km2 since 2003, leading to 59.9% growth in irrigated area and 19.5% in agricultural water use, despite a steady irrigation efficiency enhancement. Correspondingly, a substantially faster evapotranspiration increase occurred in crop expansion areas, whereas precipitation exhibited no long-term trend. Counterfactual analyses suggest that the region-wide TWS depletion is unlikely to have occurred without crop expansion-driven evapotranspiration increase even in the presence of glacier-melting. These findings imply that sustainable water management is critically needed to ensure agriculture and water security in NWC.

scholarly journals The mass balance of McCall Glacier, Brooks Range, Alaska, U.S.A.; its regional relevance and implications for climate change in the Arctic

1998 ◽  
Vol 44 (147) ◽  
pp. 333-351 ◽  
Author(s):  
B.T. Rabus ◽  
K. A. Echelmeyer
Keyword(s):  
Mass Balance ◽  
The Arctic ◽  
Balance Model ◽  
Mass Balances ◽  
Arctic Alaska ◽  
Low Mass ◽  
Length Changes ◽  
Arctic Glacier ◽  
Long Term Trend

AbstractMcCall Glacier has the only long-term mass-balance record in Arctic-Alaska. Average annual balances over the periods 1958–72 and 1972–93 were –15 and –33cm, respectively; recent annual balances (1993–96) are about –60 cm, and the mass-balance gradient has increased. For an Arctic glacier, with its low mass-exchange rate, this marks a significant negative trend.Recently acquired elevation profiles of McCall Glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973. Most of these glaciers had average annual mass balances between –25 and –33 cm, while McCall Glacier averaged –28 cm for 1956–93, indicating that it is representative of the region. In contrast, changes in terminus position for the different glaciers vary markedly. Thus, mass-balance trends in this region cannot be estimated from fractional length changes at time-scales of a few decades.We developed a simple degree-day/accumulation mass-balance model for McCall Glacier. The model was tested using precipitation and radiosonde temperatures from weather stations at Inuvik, Canada, and Barrow, Kaktovik and Fairbanks, Alaska, and was calibrated with the measured balances. The Inuvik data reproduce all measured mass balances of McCall Glacier well and also reproduce the long-term trend towards more negative balances. Data from the other stations do not produce satisfactory model results. We speculate that the Arctic Front, oriented east–west in this region, causes the differences in model results.

scholarly journals Estimation of hydrological drought recovery based on precipitation and Gravity Recovery and Climate Experiment (GRACE) water storage deficit

2021 ◽  
Vol 25 (2) ◽  
pp. 511-526
Author(s):  
Alka Singh ◽  
John Thomas Reager ◽  
Ali Behrangi
Keyword(s):  
Recovery Period ◽  
Water Storage ◽  
Precipitation Forecast ◽  
Terrestrial Water Storage ◽  
Term Trend ◽  
Drought Recovery ◽  
Terrestrial Water ◽  
Gravity Recovery ◽  
Long Term Trend

Abstract. Drought is a natural extreme climate phenomenon that presents great challenges in forecasting and monitoring for water management purposes. Previous studies have examined the use of Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage anomalies to measure the amount of water missing from a drought-affected region, and other studies have attempted statistical approaches to drought recovery forecasting based on joint probabilities of precipitation and soil moisture. The goal of this study is to combine GRACE data and historical precipitation observations to quantify the amount of precipitation required to achieve normal storage conditions in order to estimate a likely drought recovery time. First, linear relationships between terrestrial water storage anomaly (TWSA) and cumulative precipitation anomaly are established across a range of conditions. Then, historical precipitation data are statistically modeled to develop simplistic precipitation forecast skill based on climatology and long-term trend. Two additional precipitation scenarios are simulated to predict the recovery period by using a standard deviation in climatology and long-term trend. Precipitation scenarios are convolved with water deficit estimates (from GRACE) to calculate the best estimate of a drought recovery period. The results show that, in the regions of strong seasonal amplitude (like a monsoon belt), drought continues even with above-normal precipitation until its wet season. The historical GRACE-observed drought recovery period is used to validate the approach. Estimated drought for an example month demonstrated an 80 % recovery period, as observed by the GRACE.

scholarly journals A Long-term Trend of Hourly Summer Precipitation in South Korea

2016 ◽  
Vol 11 (3) ◽  
pp. 207-219
Author(s):  
Kyougmi Lee ◽  
◽  
Seungho Lee
Keyword(s):  
South Korea ◽  
Summer Precipitation ◽  
Term Trend ◽  
Long Term Trend
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