scholarly journals Extreme Precipitation and Climate Gradients in Patagonia Revealed by High-Resolution Regional Atmospheric Climate Modeling

2014 ◽  
Vol 27 (12) ◽  
pp. 4607-4621 ◽  
Author(s):  
Jan T. M. Lenaerts ◽  
Michiel R. van den Broeke ◽  
Jan M. van Wessem ◽  
Willem Jan van de Berg ◽  
Erik van Meijgaard ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Model ◽  
Climate Modeling ◽  
Atmospheric Flow ◽  
Surface Mass ◽  
Climate Gradients ◽  
The Andes ◽  
Ice Field ◽  
Regional Atmospheric Climate Model

Abstract This study uses output of a high-resolution (5.5 km) regional atmospheric climate model to describe the present-day (1979–2012) climate of Patagonia, with a particular focus on the surface mass balance (SMB) of the Patagonian ice fields. Through a comparison with available in situ observations, it is shown that the model is able to simulate the sharp climate gradients in western Patagonia. The southern Andes are an efficient barrier for the prevalent atmospheric flow, generating strong orographic uplift and precipitation throughout the entire year. The model suggests extreme orographic precipitation west of the Andes divide, with annual precipitation rates of >5 to 34 m w.e. (water equivalent), and a clear rain shadow east of the divide. These modeled precipitation rates are supported qualitatively by available precipitation stations and SMB estimates on the ice fields derived from firn cores. For the period 1979–2012, a slight atmospheric cooling at upper ice field elevations is found, leading to a small but insignificant increase in the ice field SMB.

scholarly journals Temperature and Wind Climate of the Antarctic Peninsula as Simulated by a High-Resolution Regional Atmospheric Climate Model

2015 ◽  
Vol 28 (18) ◽  
pp. 7306-7326 ◽  
Author(s):  
Jan Melchior van Wessem ◽  
Carleen H. Reijmer ◽  
Willem Jan van de Berg ◽  
Michiel R. van den Broeke ◽  
Alison J. Cook ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Antarctic Peninsula ◽  
Climate Model ◽  
Katabatic Wind ◽  
Near Surface ◽  
Climate Gradients ◽  
Climate Maps ◽  
The Antarctic ◽  
Regional Atmospheric Climate Model

Abstract The latest polar version of the Regional Atmospheric Climate Model (RACMO2.3) has been applied to the Antarctic Peninsula (AP). In this study, the authors present results of a climate run at 5.5 km for the period 1979–2013, in which RACMO2.3 is forced by ERA-Interim atmospheric and ocean surface fields, using an updated AP surface topography. The model results are evaluated with near-surface temperature and wind measurements from 12 manned and automatic weather stations and vertical profiles from balloon soundings made at three stations. The seasonal cycle of near-surface temperature and wind is simulated well, with most biases still related to the limited model resolution. High-resolution climate maps of temperature and wind showing that the AP climate exhibits large spatial variability are discussed. Over the steep and high mountains of the northern AP, large west-to-east climate gradients exist, while over the gentle southern AP mountains the near-surface climate is dominated by katabatic winds. Over the flat ice shelves, where katabatic wind forcing is weak, interannual variability in temperature is largest. Finally, decadal trends of temperature and wind are presented, and it is shown that recently there has been distinct warming over the northwestern AP and cooling over the rest of the AP, related to changes in sea ice cover.

scholarly journals Improved representation of East Antarctic surface mass balance in a regional atmospheric climate model

2014 ◽  
Vol 60 (222) ◽  
pp. 761-770 ◽  
Author(s):  
J.M. Van Wessem ◽  
C.H. Reijmer ◽  
M. Morlighem ◽  
J. Mouginot ◽  
E. Rignot ◽  
...  
Keyword(s):  
Mass Balance ◽  
Temporal Variability ◽  
Climate Model ◽  
Surface Mass Balance ◽  
West Antarctica ◽  
Surface Mass ◽  
Satellite Retrievals ◽  
Grace Satellite ◽  
Regional Atmospheric Climate Model

AbstractThis study evaluates the impact of a recent upgrade in the physics package of the regional atmospheric climate model RACMO2 on the simulated surface mass balance (SMB) of the Antarctic ice sheet. The modelled SMB increases, in particular over the grounded ice sheet of East Antarctica (+44 Gt a–1), with a small change in West Antarctica. This mainly results from an increase in precipitation, which is explained by changes in the cloud microphysics, including a new parameterization for ice cloud supersaturation, and changes in large-scale circulation patterns, which alter topographically forced precipitation. The spatial changes in SMB are evaluated using 3234 in situ SMB observations and ice-balance velocities, and the temporal variability using GRACE satellite retrievals. The in situ observations and balance velocities show a clear improvement of the spatial representation of the SMB in the interior of East Antarctica, which has become considerably wetter. No improvements are seen for West Antarctica and the coastal regions. A comparison of model SMB temporal variability with GRACE satellite retrievals shows no significant change in performance.

Physics, Resolution and Data Assimilation: Making sense of Greenland climate and ice sheet Surface Mass Balance with HARMONIE Climate

2021 ◽  
Author(s):  
Ruth Mottram ◽  
Oskar Landgren ◽  
Rasmus Anker Pedersen ◽  
Kristian Pagh Nielsen ◽  
Ole Bøssing Christensen ◽  
...  
Keyword(s):  
High Resolution ◽  
Data Assimilation ◽  
Numerical Weather Prediction ◽  
Climate Model ◽  
Weather Prediction ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass ◽  
Mass Budget ◽  
Numerical Weather

<p>The development of the HARMONIE model system has led to huge advances in numerical weather prediction, including over Greenland where a numerical weather prediction (NWP) model is used to forecast daily surface mass budget over the Greenland ice sheet as presented on polarportal.dk. The new high resolution Copernicus Arctic Reanalysis further developed the possibilities in HARMONIE with full 3DVar data assimilation and extended use of quality-controlled local observations. Here, we discuss the development and current status of the climate version of the HARMONIE Climate model (HCLIM). The HCLIM system has opened up the possibility for flexible use of the model at a range of spatial scales using different physical schemes including HARMONIE-AROME, ALADIN and ALARO for different spatial and temporal resolutions and assimilating observations, including satellite data on sea ice concentration from ESA CCI+, to improve hindcasts. However, the range of possibilities means that documenting the effects of different physics and parameterisation schemes is important before widespread application. </p><p>Here, we focus on HCLIM performance over the Greenland ice sheet, using observations to verify the different plausible set-ups and investigate biases in climate model outputs that affect the surface mass budget (SMB) of the Greenland ice sheet. </p><p>The recently funded Horizon 2020 project PolarRES will use the HCLIM model for very high resolution regional downscaling, together with other regional climate models in both Arctic and Antarctic regions, and our analysis thus helps to optimise the use of HCLIM in the polar regions for different modelling purposes.</p>

scholarly journals Characteristics of the Antarctic surface mass balance, 1958–2002, using a regional atmospheric climate model

2005 ◽  
Vol 41 ◽  
pp. 97-104 ◽  
Author(s):  
W.J. Van De Berg ◽  
M.R. Van Den Broeke ◽  
C.H. Reijmer ◽  
E. Van Meijgaard
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Solid Precipitation ◽  
Temporal And Spatial Characteristics ◽  
The Antarctic ◽  
Regional Atmospheric Climate Model

AbstractTemporal and spatial characteristics of the Antarctic specific surface mass balance (SSMB) are presented, including its components solid precipitation, sublimation/deposition and melt. For this purpose, we use the output of a regional atmospheric climate model (RACMO2/ANT, horizontal resolution of ~55 km) for the period 1958–2002. RACMO2/ANT uses European Centre for Medium-Range Weather Forecasts (ECMWF) 40 year re-analysis (ERA-40) fields as forcing at the lateral boundaries. RACMO2/ANT underestimates SSMB in the high interior of East and West Antarctica and overestimates SSMB on the steep coastal slopes. Otherwise, the modeled spatial pattern of SSMB is in good qualitative agreement with recent compilations of in situ observations. Large-scale patterns, like the precipitation shadow effect of the Antarctic Peninsula, are well reproduced, and mesoscale SSMB patterns, such as the strong precipitation gradients on Law Dome, are well represented in the model. The integrated SSMB over the grounded ice sheet is 153mmw.e. a–1 for the period 1958–2002, which agrees within 5% with the latest measurement compilations. Sublimation and melt remove 7% and <1% respectively of the solid precipitation. We found significant seasonality of solid precipitation, with a maximum in autumn and a minimum in summer. No meaningful trend was identified for the SSMB, because the time series of solid precipitation and SSMB are affected by an inhomogeneity in 1980 within the ERA-40 fields that drive RACMO2/ANT. Sublimation, melt and liquid precipitation increase in time, which is related to a modeled increase in 2m temperature.

scholarly journals Influence of Oceanic Boundary Conditions in Simulations of Antarctic Climate and Surface Mass Balance Change during the Coming Century

2008 ◽  
Vol 21 (5) ◽  
pp. 938-962 ◽  
Author(s):  
Gerhard Krinner ◽  
Bérangère Guicherd ◽  
Katia Ox ◽  
Christophe Genthon ◽  
Olivier Magand
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Boundary Conditions ◽  
Mass Balance ◽  
Climate Model ◽  
Sea Surface ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Surface Conditions ◽  
The Antarctic

Abstract This article reports on high-resolution (60 km) atmospheric general circulation model simulations of the Antarctic climate for the periods 1981–2000 and 2081–2100. The analysis focuses on the surface mass balance change, one of the components of the total ice sheet mass balance, and its impact on global eustatic sea level. Contrary to previous simulations, in which the authors directly used sea surface boundary conditions produced by a coupled ocean–atmosphere model for the last decades of both centuries, an anomaly method was applied here in which the present-day simulations use observed sea surface conditions, while the simulations for the end of the twenty-first century use the change in sea surface conditions taken from the coupled simulations superimposed on the present-day observations. It is shown that the use of observed oceanic boundary conditions clearly improves the simulation of the present-day Antarctic climate, compared to model runs using boundary conditions from a coupled climate model. Moreover, although the spatial patterns of the simulated climate change are similar, the two methods yield significantly different estimates of the amplitude of the future climate and surface mass balance change over the Antarctic continent. These differences are of similar magnitude as the intermodel dispersion in the current Intergovernmental Panel on Climate Change (IPCC) exercise: selecting a method for generating boundary conditions for a high-resolution model may be just as important as selecting the climate model itself. Using the anomaly method, the simulated mean surface mass balance change over the grounded ice sheet from 1981–2000 to 2081–2100 is 43-mm water equivalent per year, corresponding to a eustatic sea level decrease of 1.5 mm yr−1. A further result of this work is that future continental-mean surface mass balance changes are dominated by the coastal regions, and that high-resolution models, which better resolve coastal processes, tend to predict stronger precipitation changes than models with lower spatial resolution.

scholarly journals Modelling the climate and surface mass balance of polar ice sheets using RACMO2, part 2: Antarctica (1979–2016)

2017 ◽  
Author(s):  
Jan Melchior van Wessem ◽  
Willem Jan van de Berg ◽  
Brice P. Y. Noël ◽  
Erik van Meijgaard ◽  
Gerit Birnbaum ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Climate Model ◽  
Ice Sheet ◽  
Climate Scenario ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Model Version ◽  
Surface Climate

Abstract. We evaluate modelled Antarctic ice sheet (AIS) near-surface climate, surface mass balance (SMB) and surface energy balance (SEB) from the updated polar version of the regional atmospheric climate model RACMO2 (1979–2016). The updated model, referred to as RACMO2.3p2, incorporates upper-air relaxation, a revised topography, tuned parameters in the cloud scheme to generate more precipitation towards the AIS interior, and modified snow properties reducing drifting snow sublimation and increasing surface snowmelt. Comparisons of RACMO2 model output with several independent observational data show that the existing biases in AIS temperature, radiative fluxes and SMB components are further reduced with respect to the previous model version. The model integrated annual average SMB for the ice sheet including ice shelves (minus the Antarctic Peninsula (AP)) now amounts to 2229 Gt y-1, with an interannual variability of 109 Gt y-1. The largest improvement is found in modelled surface snowmelt, that now compares well with satellite and weather station observations. For the high-resolution (~ 5.5 km) AP simulation, results remain comparable to earlier studies. The updated model provides a new, high-resolution dataset of the contemporary near-surface climate and SMB of the AIS; this model version will be used for future climate scenario projections in a forthcoming study.

OBLIMAP parallelization and optimization toward high resolution climate model - ice sheet model coupler

2021 ◽  
Author(s):  
Erwan Raffin ◽  
David Guibert ◽  
Thomas Reerink
Keyword(s):  
High Resolution ◽  
Shared Memory ◽  
Large Scale ◽  
Climate Model ◽  
Climate Modeling ◽  
Parallel Implementation ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Test Case ◽  
Single Node

&lt;p&gt;Within the ESiWACE2 project we parallelized and optimized OBLIMAP. OBLIMAP is a climate model - ice sheet model coupler that can be used for offline and online coupling with embeddable mapping routines. In order to anticipate future demand concerning higher resolution and/or adaptive mesh applications, a parallel implementation of OBLIMAP's fortran code with MPI has been developed. The data intense nature of this mapping task, required a shared memory approach across the processors per compute node in order to prevent that the node memory is the limiting bottleneck. Besides, the current parallel implementation allows multi node scaling and includes parallel netcdf IO in addition with loop optimizations. Results show that the new parallel implementation offers better performance and scales well. On a single node, the shared memory approach allows now to use all the available cores, up to 128 cores in our experiments on Antarctica 20x20km test case where the original code was limited to 64 cores on this high-end node and it was even limited to 8 cores on moderate platforms. The multi node parallelization offers on Greenland 2x2km test case a speedup of 4.4x on 4 high-end compute nodes equipped with 128 cores each compared to the original code which was able to run only on 1 node. This paves the way to the establishment of OBLIMAP as an candidate ice sheet coupling library candidate for large-scale, high-resolution climate modeling.&lt;/p&gt;

Downscaling CESM2 in CLM5 to Hindcast Pre-Industrial Equilibrium Line Altitude for Tropical Mountains

2021 ◽  
Author(s):  
Nicholas Heavens
Keyword(s):  
Climate Model ◽  
Climate Modeling ◽  
Global Climate ◽  
Equilibrium Line ◽  
Lapse Rate ◽  
Surface Mass Balance ◽  
Low Resolution ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Mountain Glaciation

&lt;p&gt;Highland environments are rarely preserved in the geological record, particularly from as early as the Paleozoic Era. However, several stratigraphic locations are now known which definitely or potentially preserve such environments near the paleoequator during the Late Carboniferous and Early Permian Periods, during which the Earth was in the depths of an icehouse climate like that of the Pliocene and Pleistocene Epochs, the Late Paleozoic Ice Age (LPIA). Several of these locations contain evidence of mountain glaciation at altitudes below 2000 m, leading to questions about the significance of tropical mountain glaciation for global climate during this interval of geologic time. However, climate model simulations for the LPIA have not been able to simulate mountain glaciation like that inferred from the geological record, possibly because of low resolution, incorrect boundary conditions, or climate model bias resulting from incomplete representation of moist convective processes impacting tropical lapse rates.&amp;#160;&lt;/p&gt;&lt;p&gt;The overarching purpose of this study is to develop a climate modeling framework that enables the significance of mountain glaciation for global paleoclimate to be evaluated. Ideally, such a framework would allow low-resolution global model output to be downscaled to the scale of a mountain range to calculate the equilibrium line altitude and similar parameters, enabling evidence of mountain glaciation in the deep past to be used to constrain/tune the low-resolution global models. While this study was designed to inform a specific problem in deep time paleoclimate, its results are likely broadly applicable to assessing how well mountain glaciation is captured by global climate modeling of the past, present, and future. &amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Here, I present a framework in which the CMIP6 pre-industrial control simulation for the Community Earth System Model version 2 (CESM2) at 0.9&amp;#176;x1.25&amp;#176; resolution is used to generate a data atmosphere for the Community Land Model version 5 (CLM5) run at 0.01&amp;#176; resolution in 10 tropical and 1 mid-latitude domain to study the surface mass balance over the domain. For computational reasons, glaciation is assumed to cover a small portion of each grid cell, but surface mass balance still can be evaluated. Topographic boundary conditions come from GMTED2010, but most other information is directly interpolated from the CESM2 simulation. CLM5 simulations require a fixed lapse rate to be assumed, which is varied in each CLM5 simulation across six different values. The CLM5 simulation output along with the mean tropical lapse rate in the CESM2 simulation is then used to evaluate the various biases of this framework in comparison with estimated pre-industrial equilibrium line altitudes for the studied domains.&lt;/p&gt;&lt;p&gt;This work is supported by the National Science Foundation (USA) under grant EAR-1849754.&amp;#160;&lt;/p&gt;

scholarly journals Higher surface mass balance of the Greenland ice sheet revealed by high-resolution climate modeling

2009 ◽  
Vol 36 (12) ◽  
Author(s):  
Janneke Ettema ◽  
Michiel R. van den Broeke ◽  
Erik van Meijgaard ◽  
Willem Jan van de Berg ◽  
Jonathan L. Bamber ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Balance ◽  
Climate Modeling ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass
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