scholarly journals Historical surface mass balance from a frequency-modulated continuous-wave (FMCW) radar survey from Zhongshan station to Dome A

2020 ◽  
Vol 66 (260) ◽  
pp. 965-977
Author(s):  
Jingxue Guo ◽  
Wangxiao Yang ◽  
Yinke Dou ◽  
Xueyuan Tang ◽  
Jamin S. Greenbaum ◽  
...  
Keyword(s):  
Mass Balance ◽  
Little Ice Age ◽  
Continuous Wave ◽  
Radar Data ◽  
Ice Age ◽  
Spatiotemporal Variability ◽  
Surface Mass Balance ◽  
Dome A ◽  
Surface Mass ◽  
Zhongshan Station

AbstractUsing frequency-modulated continuous wave radar data from the 32nd Chinese Antarctic Research Expedition in 2015/16, subsurface profiles were obtained along an East Antarctic inland traverse from Zhongshan station to Dome A, and four distinct regions were selected to analyze the spatiotemporal variability in historical surface mass balance (SMB). Based on depth, density, and age data from ice cores along the traverse, the radar data were calibrated to yield average SMB data. The zone 49–195 km from the coast has the highest SMB (235 kg m−2 a−1). The 780–892 km zone was most affected by the Medieval Warm Period and the Little Ice Age, and the SMB during ad 1454–1836 (71 kg m−2 a−1) was only one-quarter of that in the 20th century. The SMB in the 1080–1157 km zone fluctuates the most, possibly due to erosion or irregular deposition of snow by katabatic winds in low SMB areas with surface elevation fluctuations. Dome A (1157–1236 km) has the lowest SMB (29 kg m−2 a−1) and did not decrease during Little Ice Age. Understanding the spatiotemporal variability of SMB in a larger space can help us understand the complex climate history of Antarctica.

scholarly journals Spatial variability of surface mass balance along a traverse route from Zhongshan station to Dome A, Antarctica

2011 ◽  
Vol 57 (204) ◽  
pp. 658-666 ◽  
Author(s):  
Ding Minghu ◽  
Xiao Cunde ◽  
Li Yuansheng ◽  
Ren Jiawen ◽  
Hou Shugui ◽  
...  
Keyword(s):  
Mass Balance ◽  
Temporal Change ◽  
Accumulation Rate ◽  
Austral Summer ◽  
Snow Accumulation ◽  
Surface Mass Balance ◽  
Dome A ◽  
Surface Mass ◽  
Zhongshan Station ◽  
Meteorological Features

AbstractStakes at 2 km intervals were installed in January 1997 and remeasured in February 1998, January 1999, January 2005 and during the 2007/08 austral summer along a 1248 km traverse route from Zhongshan station to Dome A, East Antarctica. Based on topographical parameters, meteorological features and the records of ∼650 stakes and six stake arrays, the route is divided into five zones. We find that the snow accumulation rate decreases with increasing altitude as one progresses inland, except in the zone 800–1128 km from the coast, where the average annual accumulation rate is higher than in the zone 524–800 km from the coast. The Dome A zone (1128–1248 km) has the lowest accumulation rate (35 kg m−2 a−1, 2005–08) due to having the highest elevation and being furthest from the coast. The surface mass balance in the region 202–1128 km from the coast exhibits no temporal change from 1999–2005 to 2005–08, but there is a change in the accumulation distribution. The zone from 202 to 524 km shows a decrease in surface mass balance from 84 kg m−2 a−1 in 1999–2005 to 67 kg m−2 a−1 in 2005–08, while the zone between 800 and 1128 km shows an increase from 67 kg m−2 a−1 in 1999–2005 to 75 kg m−2 a−1 in 2005–08.

scholarly journals Asynchronous behavior of outlet glaciers feeding Godthåbsfjord (Nuup Kangerlua) and the triggering of Narsap Sermia's retreat in SW Greenland

2017 ◽  
Vol 63 (238) ◽  
pp. 288-308 ◽  
Author(s):  
ROMAN J. MOTYKA ◽  
RYAN CASSOTTO ◽  
MARTIN TRUFFER ◽  
KRISTIAN K. KJELDSEN ◽  
DIRK VAN AS ◽  
...  
Keyword(s):  
Shallow Water ◽  
Mass Balance ◽  
Sea Level ◽  
Little Ice Age ◽  
Ice Age ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Tidewater Glaciers ◽  
Bed Topography ◽  
Velocity Changes

ABSTRACTWe assess ice loss and velocity changes between 1985 and 2014 of three tidewater and five-land terminating glaciers in Godthåbsfjord (Nuup Kangerlua), Greenland. Glacier thinning accounted for 43.8 ± 0.2 km3 of ice loss, equivalent to 0.10 mm eustatic sea-level rise. An additional 3.5 ± 0.3 km3 was lost to the calving retreats of Kangiata Nunaata Sermia (KNS) and Narsap Sermia (NS), two tidewater glaciers that exhibited asynchronous behavior over the study period. KNS has retreated 22 km from its Little Ice Age (LIA) maximum (1761 AD), of which 0.8 km since 1985. KNS has stabilized in shallow water, but seasonally advects a 2 km long floating tongue. In contrast, NS began retreating from its LIA moraine in 2004–06 (0.6 km), re-stabilized, then retreated 3.3 km during 2010–14 into an over-deepened basin. Velocities at KNS ranged 5–6 km a−1, while at NS they increased from 1.5 to 5.5 km a−1 between 2004 and 2014. We present comprehensive analyses of glacier thinning, runoff, surface mass balance, ocean conditions, submarine melting, bed topography, ice mélange and conclude that the 2010–14 NS retreat was triggered by a combination of factors but primarily by an increase in submarine melting.

scholarly journals Assessment of the surface mass balance along the K-transect (Greenland ice sheet) from satellite-derived albedos

2005 ◽  
Vol 42 ◽  
pp. 107-117 ◽  
Author(s):  
Wouter Greuell ◽  
Johannes Oerlemans
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Radar Data ◽  
Detection Algorithm ◽  
Surface Mass Balance ◽  
Cloud Detection ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
The Mean

AbstractThis paper explores the potential of using satellite-derived albedos to estimate the surface mass balance of the Kangerlussuaq transect (K-transect; Greenland ice sheet). We first retrieved surface albedos from Advanced Very High Resolution Radar data by using, among other techniques, a new cloud detection algorithm based on the relation between brightness temperature and surface elevation. We then computed the ‘satellite-derived mass balance’ (bsat) from the mean albedo for the transect, by taking fixed values for atmospheric transmissivity and the longwave and turbulent fluxes. We found that bsat explains 7 1% of the variance in 13 years of stake mass-balance measurements (bm). Our method also provides good estimates of the magnitude of the interannual variability in bm. The performance of the method degrades considerably without correction for anisotropic reflection at the surface and recalibration of the satellite sensors with dry snow at the top of the ice sheet. Sensitivity tests indicate that the method’s performance is hardly sensitive to uncertainties in parameters. Therefore, we expect that the method could be successfully applied on other glaciers and parts of ice sheets and ice caps, especially where accumulation rates are relatively small. We show that the investigated method performs best just below the mean equilibrium-line altitude.

The Mass Balance of Circum-Arctic Glaciers and Recent Climate Change

1997 ◽  
Vol 48 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Jon Ove Hagen ◽  
Helgi Björnsson ◽  
Andrey F. Glazovsky ◽  
William D. Harrison ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Age ◽  
The Arctic ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Negative Mass ◽  
Surface Mass ◽  
Ice Caps ◽  
Recent Climate ◽  
Arctic Ice

The sum of winter accumulation and summer losses of mass from glaciers and ice sheets (net surface mass balance) varies with changing climate. In the Arctic, glaciers and ice caps, excluding the Greenland Ice Sheet, cover about 275,000 km2of both the widely glacierized archipelagos of the Canadian, Norwegian, and Russian High Arctic and the area north of about 60°N in Alaska, Iceland, and Scandinavia. Since the 1940s, surface mass balance time-series of varying length have been acquired from more than 40 Arctic ice caps and glaciers. Most Arctic glaciers have experienced predominantly negative net surface mass balance over the past few decades. There is no uniform recent trend in mass balance for the entire Arctic, although some regional trends occur. Examples are the increasingly negative mass balances for northern Alaska, due to higher summer temperatures, and increasingly positive mass balances for maritime Scandinavia and Iceland, due to increased winter precipitation. The negative mass balance of most Arctic glaciers may be a response to a step-like warming in the early twentieth century at the termination of the cold Little Ice Age. Arctic ice masses outside Greenland are at present contributing about 0.13 mm yr−1to global sea-level rise.

scholarly journals The Spatiotemporal Variability of Cloud Radiative Effects on the Greenland Ice Sheet Surface Mass Balance

2020 ◽  
Vol 47 (12) ◽  
Author(s):  
M. Izeboud ◽  
S. Lhermitte ◽  
K. Van Tricht ◽  
J. T. M. Lenaerts ◽  
N. P. M. Van Lipzig ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Spatiotemporal Variability ◽  
Surface Mass Balance ◽  
Radiative Effects ◽  
Surface Mass ◽  
Sheet Surface ◽  
Cloud Radiative Effects

scholarly journals Spatial distribution of surface mass balance on Amundsenisen plateau, Antarctica, derived from ice-penetrating radar studies

2004 ◽  
Vol 39 ◽  
pp. 265-270 ◽  
Author(s):  
Gerit Rotschky ◽  
Olaf Eisen ◽  
Frank Wilhelms ◽  
Uwe Nixdorf ◽  
Hans Oerter
Keyword(s):  
Mass Balance ◽  
Ice Core ◽  
Ice Cores ◽  
Radar Data ◽  
Small Scale ◽  
Surface Mass Balance ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
Correlation Lengths ◽  
Current Utilization

AbstractThe distribution of surface mass balance on Amundsenisen, Dronning Maud Land, Antarctica, is investigated along a continous profile line. Ice-penetrating radar is used to map variations in ice-layer thickness within the upper 100 m of the ice sheet. The route passes several firn- and ice-core drilling sites over a distance of 320 km. Dielectric-profiling data of ice cores are used to calculate the depths of selected reflection horizons and the cumulative mass of the ice column. The local surface mass balance is determined as a temporal average, covering a time-span of almost two centuries. The findings indicate a complex accumulation pattern superimposed on a generally low surface mass balance, which is related to small-scale surface undulations. The results of the radar soundings are in general in good agreement with surface mass-balance data derived from firn-core studies. Discrepancies between these two datasets can be explained by spatial mismatch or by minor quality of either ice-core profiles or radar data. For regional comparison of radar-based accumulation data we use an accumulation distribution interpolated from point measurements. The surface mass balance varies up to 50% over short distances, with correlation lengths of <10 km. We conclude that the current utilization schemes of point sampling are only capable of reproducing local values and regional trends but provide no information on the small-scale variability of surface mass balance.

Surface mass balance and its climate significance from the coast to Dome A, East Antarctica

2015 ◽  
Vol 58 (10) ◽  
pp. 1787-1797 ◽  
Author(s):  
MingHu Ding ◽  
CunDe Xiao ◽  
ChuanJin Li ◽  
DaHe Qin ◽  
Bo Jin ◽  
...  
Keyword(s):  
Mass Balance ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Dome A ◽  
Surface Mass

scholarly journals Simulating asymmetric growth and retreat of Hardangerjøkulen ice cap in southern Norway since the mid-Holocene

2016 ◽  
Author(s):  
Henning Åkesson ◽  
Kerim H. Nisancioglu ◽  
Rianne H. Giesen ◽  
Mathieu Morlighem
Keyword(s):  
Mass Balance ◽  
Ice Age ◽  
Dynamical Response ◽  
Surface Mass Balance ◽  
Outlet Glacier ◽  
Surface Mass ◽  
Ice Caps ◽  
Ice Cap ◽  
Length Changes ◽  
Southern Norway

Abstract. Changes to the volume of glaciers and ice caps currently amount to half of the total cryospheric contribution to sea-level rise and are projected to remain substantial throughout the 21st century. To simulate glacier behavior on centennial and longer time scales, models rely on simplified dynamics and tunable parameters for processes not well understood. Model calibration is often done using present-day observations, even though the relationship between parameters and parametrized processes may be altered for significantly different glacier states. In this study, we simulate the evolution of the Hardangerjøkulen ice cap in southern Norway from the mid-Holocene through the Little Ice Age (LIA) to the present-day. For both the calibration and transient experiments, we run an ensemble using a two-dimensional ice flow model with local mesh refinement. For the Holocene, we apply a simple surface mass balance forcing based on climate reconstructions. For the LIA until 1962, we use geomorphological evidence and measured outlet glacier positions to find a mass balance history, while from 1963 until today we use direct mass balance measurements. Given a linear climate forcing, we find that Hardangerjøkulen grew from ice-free conditions in the mid-Holocene, to its maximum LIA extent in a highly non-linear fashion. During the fastest stage of growth (2200-1200 BP), the ice cap tripled its ice volume over only 1000 years. We also reveal an intriguing spatial asymmetry during advance and retreat; the western ice cap and the northern outlet glacier Midtdalsbreen grow first and disappear first. In contrast, the eastern part, including the northeastern outlet glacier Blåisen, grows last and disappears last. Furthermore, volume and area of several outlet glaciers, as well as of the entire ice cap, vary out-of-phase for multiple centuries during the late Holocene, before varying in-phase approaching the LIA. We relate this to bed topography and the mass balance-altitude feedback, and challenge canonical linear assumptions between ice cap extent and glacier proxy records. Thus, we provide new insight into long-term dynamical response of ice caps to climate change, relevant for paleoglaciological studies and future predictions. Our model simulates ice cap extent and outlet glacier length changes from the LIA until today that are close to observations. We show that present-day Hardangerjøkulen is extremely sensitive to surface mass balance changes, mainly due to a strong mass balance-altitude feedback for the gently sloping surface topography of the ice cap.

scholarly journals Inversion for the density–depth profile of Dome A, East Antarctica, using frequency-modulated continuous wave radar

2021 ◽  
pp. 1-15
Author(s):  
Wangxiao Yang ◽  
Yinke Dou ◽  
Bo Zhao ◽  
Jingxue Guo ◽  
Xueyuan Tang ◽  
...  
Keyword(s):  
Mass Balance ◽  
Continuous Wave ◽  
Critical Density ◽  
Ice Sheet ◽  
Ice Cores ◽  
Radar Data ◽  
Balance Model ◽  
Densification Rate ◽  
Dome A ◽  
Wave Radar

Abstract The density–depth relationship of the Antarctic ice sheet is important for establishing a high-precision surface mass balance model and predicting future ice-sheet contributions to global sea levels. A new algorithm is used to reconstruct firn density and densification rate by inverting monostatic radio wave echoes from ground-operated frequency-modulated continuous wave radar data collected near four ice cores along the transect from Zhongshan Station to Dome A. The inverted density profile is consistent with the core data within 5.54% root mean square error. Due to snow redistribution, the densification rate within 88 km of ice core DT401 is correlated with the accumulation rate and varies greatly over horizontal distances of <5 km. That is, the depth at which a critical density of 830 kg m−3 is reached decreases and densification rate increases in high-accumulation regions but decreases in low-accumulation regions. This inversion technique can be used to analyse more Antarctic radar data and obtain the density distribution trend, which can improve the accuracy of mass-balance estimations.

scholarly journals Greenland Ice Sheet Mass Balance Reconstruction. Part II: Surface Mass Balance (1840–2010)*

2013 ◽  
Vol 26 (18) ◽  
pp. 6974-6989 ◽  
Author(s):  
Jason E. Box
Keyword(s):  
Mass Balance ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Ice Age ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Regional Climate Model Output

Abstract Meteorological station records, ice cores, and regional climate model output are combined to develop a continuous 171-yr (1840–2010) reconstruction of Greenland ice sheet climatic surface mass balance (Bclim) and its subcomponents including near-surface air temperature (SAT) since the end of the Little Ice Age. Independent observations are used to assess and compensate errors. Melt water production is computed using separate degree-day factors for snow and bare ice surfaces. A simple meltwater retention scheme yields the time variation of internal accumulation, runoff, and bare ice area. At decadal time scales over the 1840–2010 time span, summer (June–August) SAT increased by 1.6°C, driving a 59% surface meltwater production increase. Winter warming was +2.0°C. Substantial interdecadal variability linked with episodic volcanism and atmospheric circulation anomalies is also evident. Increasing accumulation and melt rates, bare ice area, and meltwater retention are driven by increasing SAT. As a consequence of increasing accumulation and melt rates, calculated meltwater retention by firn increased 51% over the period, nearly compensating a 63% runoff increase. Calculated ice sheet end of melt season bare ice area increased more than 5%. Multiple regression of interannual SAT and precipitation anomalies suggests a dominance of melting on Bclim and a positive SAT precipitation sensitivity (+32 Gt yr−1 K−1 or 6.8% K−1). The Bclim component magnitudes from this study are compared with results from Hanna et al. Periods of shared interannual variability are evident. However, the long-term trend in accumulation differs in sign.

Sign in / Sign up

Export Citation Format

Share Document