scholarly journals Greenland surface air temperature changes from 1981 to 2019 and implications for ice‐sheet melt and mass‐balance change

2020 ◽  
Author(s):  
Edward Hanna ◽  
John Cappelen ◽  
Xavier Fettweis ◽  
Sebastian H. Mernild ◽  
Thomas L. Mote ◽  
...  
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Ice Sheet ◽  
Surface Air Temperature ◽  
Temperature Changes

scholarly journals The Greenland ice sheet: modelling the surface mass balance from GCM output with a new statistical downscaling technique

2013 ◽  
Vol 7 (3) ◽  
pp. 3163-3207 ◽  
Author(s):  
M. Geyer ◽  
D. Salas Y Melia ◽  
E. Brun ◽  
M. Dumont
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Statistical Downscaling ◽  
Ice Sheet ◽  
Coupled Model ◽  
Surface Air Temperature ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass

Abstract. The aim of this study is to derive a realistic estimation of the Surface Mass Balance (SMB) of the Greenland ice sheet (GrIS) through statistical downscaling of Global Coupled Model (GCM) outputs. To this end, climate simulations performed with the CNRM-CM5.1 Atmosphere-Ocean GCM within the CMIP5 (Coupled Model Intercomparison Project phase 5) framework are used for the period 1850–2300. From the year 2006, two different emission scenarios are considered (RCP4.5 and RCP8.5). Simulations of SMB performed with the detailed snowpack model Crocus driven by CNRM-CM5.1 surface atmospheric forcings serve as a reference. On the basis of these simulations, statistical relationships between total precipitation, snow-ratio, snowmelt, sublimation and near-surface air temperature are established. This leads to the formulation of SMB variation as a function of temperature variation. Based on this function, a downscaling technique is proposed in order to refine 150 km horizontal resolution SMB output from CNRM-CM5.1 to a 15 km resolution grid. This leads to a much better estimation of SMB along the GrIS margins, where steep topography gradients are not correctly represented at low-resolution. For the recent past (1989–2008), the integrated SMB over the GrIS is respectively 309 and 243 Gt yr–1 for raw and downscaled CNRM-CM5.1. In comparison, the Crocus snowpack model forced with ERA-Interim yields a value of 245 Gt yr–1. The major part of the remaining discrepancy between Crocus and downscaled CNRM-CM5.1 SMB is due to the different snow albedo representation. The difference between the raw and the downscaled SMB tends to increase with near-surface air temperature via an increase in snowmelt.

scholarly journals Sensitivity of glacier runoff to summer snowfall events

2007 ◽  
Vol 46 ◽  
pp. 309-315 ◽  
Author(s):  
Heidi Escher-Vetter ◽  
Matthias Siebers
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Meteorological Data ◽  
Precipitation Data ◽  
Clear Trend ◽  
Temperature Changes ◽  
Ablation Area ◽  
Glacier Runoff ◽  
Precipitation Type

AbstractIn order to investigate the effect of changing precipitation type on glacier discharge due to air-temperature changes, the relation between summer snowfall and runoff is surveyed for the Vernagtbach basin, Austria, (2640–3630ma.s.l.; ~72% glaciated) for the period 1976–2005. Precipitation data were evaluated for each ablation season with respect to amount and type; the latter derived mainly from daily photographs of the catchment, but validated over 4 years with additional meteorological data. Winter snowfall amounts were determined on the basis of mass-balance measurements. Average ablation period air temperature showed a rise of 1.5 K from 1976 to 2005, and runoff increased from about 1100 mmw.e. to 2200 mmw.e. Snowfall amounts during the ablation period decreased between 1976 and 1991, but increased from 1992 to 2005, indicating a large year-to-year variation. The number of days with snowfall varies even more, with no clear trend discernible. The evolution of runoff is only partly explained by precipitation type during the ablation season, and accumulation amounts during winter deliver a not unambiguous picture. More important is the development of the ablation area from about 20% of glacier size in the 1970s to 100% in 2003.

scholarly journals Recent air-temperature changes in the Arctic

2007 ◽  
Vol 46 ◽  
pp. 316-324 ◽  
Author(s):  
Rajmund Przybylak
Keyword(s):  
Air Temperature ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Marked Rise ◽  
Temperature Changes ◽  
The Pacific ◽  
Complete Series ◽  
Linear Effects ◽  
Autumn And Winter ◽  
Abrupt Rise

AbstractA detailed analysis of the spatial and temporal changes in mean seasonal and annual surface air temperature (SAT) in the Arctic is presented mainly for the period 1951–2005. Mean seasonal and annual homogenized and complete series of SAT from up to 35 Arctic stations were used in the analysis. The focus in this paper is on the 11 years 1995–2005, a period which saw dramatic warming in the Arctic (>1˚C for annual values in relation to the 1951–90 mean). An abrupt rise in SAT occurred in the mid-1990s and was most pronounced in autumn and winter (>2˚C). The greatest warming in the period 1995–2005 occurred in the Pacific and Canadian regions (>1˚C), while the lowest was in the Siberian region (0.82˚C). This period has been the warmest since at least the 17th century. In particular, 2005 was an exceptionally warm year (>2˚C in relation to the 1951–90 mean) and was warmer than 1938, the warmest year in the 20th century. The seasonal and annual trends of the areally averaged Arctic SAT for the periods 1936–2005, 1951–2005 and 1976–2005 are positive, with the exception of winter and autumn for the first period. The majority of trends calculated for the last two periods are statistically significant. While there are varying opinions about the forces driving the present warming, it seems likely that the marked rise in SAT in the mid-1990s (mainly from 1994 to 1995) was caused by (i) a set of natural factors, (ii) non-linear effects of greenhouse-gas loading, or (iii) the combined effect of these two groups of factors.

scholarly journals Impact of stratospheric aerosol intervention geoengineering on surface air temperature in China: A surface energy budget perspective

2021 ◽  
Author(s):  
Zhaochen Liu ◽  
Xianmei Lang ◽  
Dabang Jiang
Keyword(s):  
Spatial Pattern ◽  
Air Temperature ◽  
Land Surface ◽  
Surface Albedo ◽  
Surface Air Temperature ◽  
Stratospheric Aerosol ◽  
Surface Energy Budget ◽  
Shortwave Radiation ◽  
Surface Cooling ◽  
Temperature Changes

Abstract. Stratospheric aerosol intervention (SAI) geoengineering is a rapid, effective, and promising means to counteract anthropogenic global warming, but the climate response to SAI, with great regional disparities, remains uncertain. In this study, we use Geoengineering Model Intercomparison Project G4 experiment simulations from three models (HadGEM2-ES, MIROC-ESM, and MIROC-ESM-CHEM) that offset anthropogenic forcing under medium-low emissions (RCP4.5) by injecting a certain amount of SO2 into the stratosphere every year, to investigate the surface air temperature response to SAI geoengineering over China. It has been shown that the SAI leads to surface cooling over China over the last 40 years of injection simulation (2030–2069), which varies among models, regions and seasons. The spatial pattern of SAI-induced temperature changes over China is mainly due to net surface shortwave radiation changes. We find that changes in solar radiation modification strength, surface albedo, atmospheric water vapor and cloudiness affect surface shortwave radiation. In summer, the increased cloud cover in some regions reduces net surface shortwave radiation, causing strong surface cooling. In winter, both the strong cooling in all three models and the abnormal warming in MIROC-ESM are related to surface albedo changes. Our results suggest that cloud and land surface processes in models may dominate the spatial pattern of SAI-induced surface air temperature changes over China.

scholarly journals Evaluation of Greenland near surface air temperature datasets

2017 ◽  
Vol 11 (4) ◽  
pp. 1591-1605 ◽  
Author(s):  
J. E. Jack Reeves Eyre ◽  
Xubin Zeng
Keyword(s):  
Air Temperature ◽  
Mean Absolute Error ◽  
Ice Sheet ◽  
Surface Air Temperature ◽  
Absolute Error ◽  
Near Surface ◽  
Satellite Retrieval ◽  
Highly Correlated ◽  
Global Reanalysis

Abstract. Near-surface air temperature (SAT) over Greenland has important effects on mass balance of the ice sheet, but it is unclear which SAT datasets are reliable in the region. Here extensive in situ SAT measurements ( ∼  1400 station-years) are used to assess monthly mean SAT from seven global reanalysis datasets, five gridded SAT analyses, one satellite retrieval and three dynamically downscaled reanalyses. Strengths and weaknesses of these products are identified, and their biases are found to vary by season and glaciological regime. MERRA2 reanalysis overall performs best with mean absolute error less than 2 °C in all months. Ice sheet-average annual mean SAT from different datasets are highly correlated in recent decades, but their 1901–2000 trends differ even in sign. Compared with the MERRA2 climatology combined with gridded SAT analysis anomalies, thirty-one earth system model historical runs from the CMIP5 archive reach  ∼  5 °C for the 1901–2000 average bias and have opposite trends for a number of sub-periods.

scholarly journals What Drives the North Atlantic Oscillation’s Temperature Anomaly Pattern? Part I: The Growth and Decay of the Surface Air Temperature Anomalies

2019 ◽  
Vol 77 (1) ◽  
pp. 185-198 ◽  
Author(s):  
Joseph P. Clark ◽  
Steven B. Feldstein
Keyword(s):  
Skin Temperature ◽  
Air Temperature ◽  
Temperature Anomaly ◽  
Surface Air Temperature ◽  
Temperature Changes ◽  
Temperature Anomalies ◽  
The North ◽  
Temperature Advection ◽  
Anomaly Pattern ◽  
Air Temperature Anomaly

Abstract Composite analysis is used to examine the physical processes that drive the growth and decay of the surface air temperature anomaly pattern associated with the North Atlantic Oscillation (NAO). Using the thermodynamic energy equation that the European Centre for Medium-Range Weather Forecasts implements in their reanalysis model, we show that advection of the climatological temperature field by the anomalous wind drives the surface air temperature anomaly pattern for both NAO phases. Diabatic processes exist in strong opposition to this temperature advection and eventually cause the surface air temperature anomalies to return to their climatological values. Specifically, over Greenland, Europe, and the United States, longwave heating/cooling opposes horizontal temperature advection while over northern Africa vertical mixing opposes horizontal temperature advection. Despite the pronounced spatial correspondence between the skin temperature and surface air temperature anomaly patterns, the physical processes that drive these two temperature anomalies associated with the NAO are found to be distinct. The skin temperature anomaly pattern is driven by downward longwave radiation whereas stated above, the surface air temperature anomaly pattern is driven by horizontal temperature advection. This implies that the surface energy budget, although a useful diagnostic tool for understanding skin temperature changes, should not be used to understand surface air temperature changes.

scholarly journals Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers

2012 ◽  
Vol 6 (4) ◽  
pp. 821-839 ◽  
Author(s):  
J. E. Box ◽  
X. Fettweis ◽  
J. C. Stroeve ◽  
M. Tedesco ◽  
D. K. Hall ◽  
...  
Keyword(s):  
Air Temperature ◽  
Negative Feedback ◽  
Ice Sheet ◽  
Surface Air Temperature ◽  
Greenland Ice Sheet ◽  
Dominant Factor ◽  
Water Runoff ◽  
Albedo Feedback ◽  
Ablation Area ◽  
Surface Melt

Abstract. Greenland ice sheet mass loss has accelerated in the past decade responding to combined glacier discharge and surface melt water runoff increases. During summer, absorbed solar energy, modulated at the surface primarily by albedo, is the dominant factor governing surface melt variability in the ablation area. Using satellite-derived surface albedo with calibrated regional climate modeled surface air temperature and surface downward solar irradiance, we determine the spatial dependence and quantitative impact of the ice sheet albedo feedback over 12 summer periods beginning in 2000. We find that, while albedo feedback defined by the change in net solar shortwave flux and temperature over time is positive over 97% of the ice sheet, when defined using paired annual anomalies, a second-order negative feedback is evident over 63% of the accumulation area. This negative feedback damps the accumulation area response to warming due to a positive correlation between snowfall and surface air temperature anomalies. Positive anomaly-gauged feedback concentrated in the ablation area accounts for more than half of the overall increase in melting when satellite-derived melt duration is used to define the timing when net shortwave flux is sunk into melting. Abnormally strong anticyclonic circulation, associated with a persistent summer North Atlantic Oscillation extreme since 2007, enabled three amplifying mechanisms to maximize the albedo feedback: (1) increased warm (south) air advection along the western ice sheet increased surface sensible heating that in turn enhanced snow grain metamorphic rates, further reducing albedo; (2) increased surface downward shortwave flux, leading to more surface heating and further albedo reduction; and (3) reduced snowfall rates sustained low albedo, maximizing surface solar heating, progressively lowering albedo over multiple years. The summer net infrared and solar radiation for the high elevation accumulation area approached positive values during this period. Thus, it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming.

scholarly journals Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

2018 ◽  
Vol 12 (4) ◽  
pp. 1211-1232 ◽  
Author(s):  
Ulrike Falk ◽  
Damián A. López ◽  
Adrián Silva-Busso
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
High Variability ◽  
South Shetland Islands ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Potter Cove ◽  
Shetland Islands ◽  
Ice Cap

Abstract. The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP). This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0K(100m)-1) and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the wintertime over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as 5 years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift in the difference between simulated mass balance and mass balance measurements can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in meltwater input to the coastal waters, specific glacier mass balance and the equilibrium line altitude (ELA). The Fourcade Glacier catchment drains into Potter cove, has an area of 23.6 km2 and is glacierized to 93.8 %. Annual discharge from Fourcade Glacier into Potter Cove is estimated to q¯=25±6hm3yr-1 with the standard deviation of 8 % annotating the high interannual variability. The average ELA calculated from our own glaciological observations on Fourcade Glacier over the time period 2010 to 2015 amounts to 260±20 m. Published studies suggest rather stable conditions of slightly negative glacier mass balance until the mid-1980s with an ELA of approx. 150 m. The calculated accumulation area ratio suggests dramatic changes in the future extent of the inland ice cap for the South Shetland Islands.

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