Simulation and Optimisation for the Radar Echo Telescope for Cosmic Rays

The polar ice sheets are melting faster due to climate change, with the contribution of the Greenland and Antarctic ice sheets being the largest uncertainty in projecting future sea level rise. Understanding this is crucial for assessing impacts on the environment and ecosystems. Most of the existing modelling studies focus on ice sheet response to atmospheric and oceanic forcing. However, the ice sheets closely interact with and influence the Earth’s climate. With the goal of better representing ice sheet and climate processes and feedbacks, we aim to integrate Greenland and Antarctic dynamic ice sheet components into the Norwegian Earth System Model (NorESM). NorESM is a global, CMIP-type coupled model for the physical climate system and biogeochemical processes over land, ocean, sea ice and atmosphere. In its latest release, NorESM features interactive coupling with a dynamic Greenland Ice Sheet (GrIS) component, although this coupling does not explicitly include ocean forcing at the marine-terminating margins of the ice sheet. In this presentation, we will show preliminary results of NorESM simulations featuring (1) a new interactive coupling with the Community Ice Sheet Model (CISM) over both the Antarctic and Greenland domains, and (2) a new ocean and ice sheet coupling allowing us to force the ice sheets with horizontally and vertically resolved  NorESM ocean properties. We will discuss work in progress, highlighting recent advances and most pressing challenges of our coupling approach.

The present-day perturbations of the Earth's rotation are sensitive to the glacial isostatic adjustment (GIA) arising from the Late Pleistocene glacial cycles and also to the recent mass balance of polar ice caps. In this study, we evaluate the polar wander and the change of degree-two harmonic of the Earth's geopotential , proportional to the rotation rate, for four Late Pleistocene ice models. We examine these perturbations as a function of lower- and upper-mantle viscosities and lithospheric thickness and rheology (elastic or viscoelastic), in which a compressible Earth model with elasticity and density given by the seismological model PREM is used. By considering the observations and predictions including the GIA process arising from the Late Pleistocene ice and recent mass balance of polar ice caps, we discuss the recent mass balance of the Antarctic and Greenland ice sheets. We also examine the effects of internal processes and the melting of mountain glaciers, although this work is only preliminary. The results shown below seem to be supported even if these effects are included. Two solutions are obtained for source areas of the recent Antarctic melting. We denote an equivalent sea level (ESL) rise (mm yr−1)) from the Greenland and Antarctic ice sheets as and , respectively, being positive for melting and negative for growth. One, solution s1, is a solution satisfying the relationship , and the other, solution s2, generally satisfies the relationship and . In most cases, the magnitude of for solution s2 is larger than that for solution s1. The melting area of the Antarctic ice sheet for solution s1 roughly corresponds to the Weddell Sea region, approximately located on the symmetric part of Greenland to the Equator. The area for solution s2 is located on the symmetric part of Greenland to the centre of the Earth. In both solutions, therefore, the polar wander direction caused by the mass imbalance of each ice sheet is in an opposite direction. The reason for this is that the observed polar wander direction is nearly identical to the prediction from the GIA process for the Late Pleistocene ice models. However, it is difficult to independently examine which solution is better. If we consider a recent ESL rise of ∼0.6 mm yr−1 from the Greenland ice sheet, then a similar ESL rise of 0.5–1.0 mm yr−1 is also suggested for the Antarctic ice sheet around the Weddell Sea region. This solution also suggests the lower-mantle viscosity to be ∼1022 Pa s.

<p>Ice sheets and the rest of the climate system interact in various ways, notably via the atmosphere, ocean and solid earth. Atmospheric and oceanic temperatures and circulations affect the evolution of ice-sheets, and conversely ice-sheet evolution impacts the rest of the climate system via various processes, including albedo modification, topographic changes and freshwater flux release into the ocean. To correctly model the evolution of the climate system and sea level rise, these feedbacks therefore need to be considered.</p><p>Under the highest emission scenario, temperature is expected to reach levels comparable to the Eocene epoch in a few centuries [1]. At this time, there was no widespread glaciation in Antarctica.</p><p>The work of Garbe et al [2] has shown that the Antarctic ice sheet has a hysteresis behavior and gave different temperature thresholds leading to committed Antarctic mass loss. For example, between 6 and 9 degrees of warming (a global temperature increase comparable to the one expected in 2300 for the most emissive scenario), the loss of 70% of the present-day ice volume is triggered. However, the modelling study used idealized perturbations of the climate fields based solely on global mean temperature. More specifically, global mean temperature is translated into local changes of ocean and surface air temperature and increased until a complete deglaciation of the Antarctic ice-sheet is reached. In addition the study did not take into account the ice sheet change feedback on the climate system.</p><p>In our work we intend to go a step further by taking into account both the influence of atmosphere and oceanic temperature and circulations on the ice sheet in a physical way, as well as the influence of the ice sheet on the rest of the climate system.</p><p>To do so, we use the coupled ocean-atmosphere-vegetation intermediate complexity model iLOVECLIM [3], fully coupled to the GRISLI ice-sheet model for Antarctica [4, 5].</p><p>We perform several multi-millenia equilibria simulations for different pCO2 levels, thanks to the relative rapidity of both the iLOVECLIM and GRISLI models. These simulations lead to different atmospheric and oceanic temperatures and Antarctic mass loss. </p><p>These coupled simulations allow us to explore the impact of the ice sheet feedback on the climate and to investigate the differences compared to cases where these feedbacks are not included. The influence of the model parameters linked to the ice sheet coupling is also studied.</p><p> </p><p>References :</p><p>[1] Westerhold et al 2020, “An astronomically dated record of Earth’s climate and its predictability over the last 66 million years”</p><p>[2] Garbe et al 2020 “The hysteresis of the Antarctic Ice Sheet”</p><p>[3] Quiquet et al 2018, “Online dynamical downscaling of temperature and precipitation within the <em>i</em>LOVECLIM model (version 1.1)”</p><p>[4] Quiquet et al 2018, “The GRISLI ice sheet model (version 2.0): calibration and validation for multi-millennial changes of the Antarctic ice sheet”</p><p>[5] Quiquet et al 2021 “Climate and ice sheet evolutions from the last glacial maximum to the pre-industrial period with an ice-sheet–climate coupled model”</p>

A model of the Antarctic ice sheet has been used to simulate the ice sheet in warmer climates, in order to investigate what kind of ice-sheet geometries one can reasonably expect under what kind of climatic conditions and to discover which physical mechanisms may be involved to explain them. The results of these experiments reveal the considerable stability of; in particular, the East Antarctic ice sheet. It would require a temperature rise of between 17 and 20 K above present levels to remove this ice sheet from the subglacial basins in the interior of the continent and of 25 K to melt down the Antarctic ice sheet completely. For a temperature rise below 5 K, the model actually predicts a larger Antarctic ice sheet than today as a result of increased snowfall, whereas the west Antarctic ice sheet was round not to survive temperatures more than 8–10 K above present values. Furthermore, basal temperature conditions in these experiments point to the problems involved in raising the base of the ice sheet to the pressure-melting point over the large areas necessary to consider the possibility of sliding instability. These results bear on a lively debate regarding the late Cenozoic glacial history of Antarctica. Particularly, based on these findings, it is difficult to reconcile a highly variable East Antarctic ice sheet until the Pliocene with modest warming recorded in, for instance, the deep-sea records for the late Neogene.

Weather radar echo prediction method based on convolution neural network and Long Short-Term memory networks for sustainable e-agriculture

The rate and magnitude of the Antarctic Ice Sheet (AIS) contribution to global sea-level rise beyond 2100 ce remains highly uncertain. Past changes of the AIS, however, offer opportunities to understand contemporary and future ice sheet behaviour. In this Review, we outline how the AIS evolved through the pre-industrial Holocene, 11,700 years ago to 1850 ce. Three main phases of ice sheet behaviour are identified: a period of rapid ice volume loss across all sectors in the Early and Mid Holocene; a retreat inland of the present-day ice sheet margin in some sectors, followed by readvance; and continued ice volume loss in several sectors during the past few millennia, and in some areas up to and into the industrial era. Global sea levels rose by 2.4–12 m owing to the period of rapid Antarctic ice loss and possibly fell by 0.35–1.2 m owing to subsequent readvance. Changes in the AIS during the Holocene were likely driven by similar processes to those acting today and predicted for the future, which are associated with oceanic and atmospheric conditions as well as bed topography. Further work is required to better understand these processes and to quantify Antarctica’s contribution to past sea-level change. The Antarctic Ice Sheet (AIS) underwent dramatic changes over the Holocene, impacting global sea levels. In this Review, Jones et al. discuss changes in this ice sheet during the pre-industrial Holocene. The drivers behind these past changes are explored, as well as their relevance for current and future changes in the AIS.

<p>In recent decades, global warming has driven significant mass losses across the Antarctic Ice Sheet (AIS). Global warming of 1.5◦C and 2◦C is expected to be exceeded in the coming decades, which will trigger further AIS instabilities (Pattyn et al., 2018; Pörtner et al., 2022). The AIS has the potential to be the largest contributor to global sea level rise; thus, it is essential to understand the dynamics of the AIS in a warming world to aid governmental policies. The most significant mass losses in the AIS are driven by ocean-forced basal melting reducing the buttressing ability of ice shelves. The Ross Ice Shelf (RIS) is the largest cold water ice shelf on the AIS and buttresses the West and East Antarctic Ice Sheet. Understanding the current dynamics of the RIS in a warming world is important as the ice shelf has a large control over the mass balance of the AIS. Seasonal changes in sea ice cover have recently been found to elevate basal melt rates at the calving front of the RIS (Stewart et al., 2019). This thesis sets out to understand the influence of short-term environmental variability on RIS flow dynamics. This will be achieved through observing the RIS flow rates over seasonal and interannual timescales using GNSS and remote sensing methods. Exploration of environmental drivers of the observed flow variability is carried out using the Ice-sheet and Sea-level System Model (ISSM). Furthermore, ISSM is used to quantify sensitive areas of the RIS to changes in glaciology and environmental controls. The results showed that the RIS flow rates do not vary significantly on seasonal or interannual timescales, suggesting that the RIS dynamics are insensitive to external forcings at seasonal and interannual frequencies. However, basal melting was found to drive seasonal variations in ice flow dynamics with similar patterns to the GNSS velocities. The sensitivity maps highlighted that changes in basal melt in sensitive areas (i.e., grounding lines and shear margins) would impact the mass balance substantially and should be monitored in a warming world. The simulations could not replicate the observed velocity variations suggesting that some other environmental forcing not considered is driving these variations. Projections of the RIS and AIS using a range of climate models and present-day basal melt conditions were also performed in ISSM to understand whether short-term basal melt variability should be included in projections and the influence basal melt parameterisation inputs have on the final projected sea level contribution. The results showed that including short-term basal melt variability was not needed to project the mass changes of the RIS, with variability in surface mass balance driving larger changes in the mass balance over a 100 year timescale. However, using high spatio-temporal resolution datasets within the basal melt parameterisation projected larger basal melt rates, mass loss and sea level contributions for the AIS. Thus, uncertainties still exist in ice sheet modelled projections of sea level rise estimates, and policymakers should use multiple model simulations when planning adaptive strategies.</p>

Deep sea geological records indicate that Antarctic ice-sheet growth and decay is strongly influenced by the Earth’s astronomical variations (known as Milankovitch cycles), and that the frequency of the glacial–interglacial cycles changes through time. Here we examine the emergence of a strong obliquity (axial tilt) control on Antarctic ice-sheet evolution during the Miocene by correlating the Antarctic margin geological records from 34 to 5 million years ago with a measure of obliquity sensitivity that compares the variance in deep sea sediment core oxygen-isotope data at obliquity timescales with variance of the calculated obliquity forcing. Our analysis reveals distinct phases of ice-sheet evolution and suggests the sensitivity to obliquity forcing increases when ice-sheet margins extend into marine environments. We propose that this occurs because obliquity-driven changes in the meridional temperature gradient affect the position and strength of the circum-Antarctic easterly flow and enhance (or reduce) ocean heat transport across the Antarctic continental margin. The influence of obliquity-driven changes in ocean dynamics is amplified when marine ice sheets are extensive, and sea ice is limited. Our reconstruction of the Antarctic ice-sheet history suggests that if sea-ice cover decreases in the coming decades, ocean-driven melting at the ice-sheet margin will be amplified. The sensitivity of the Antarctic ice sheet to obliquity increases when ice-sheet margins are exposed to the ocean, suggests an analysis of sediment core oxygen isotope records.

Abstract. The Antarctic Ice Sheet represents the largest source of uncertainty in future sea level rise projections, with a contribution to sea level by 2100 ranging from −5 to 43 cm of sea level equivalent under high carbon emission scenarios estimated by the recent Ice Sheet Model Intercomparison for CMIP6 (ISMIP6). ISMIP6 highlighted the different behaviors of the East and West Antarctic ice sheets, as well as the possible role of increased surface mass balance in offsetting the dynamic ice loss in response to changing oceanic conditions in ice shelf cavities. However, the detailed contribution of individual glaciers, as well as the partitioning of uncertainty associated with this ensemble, have not yet been investigated. Here, we analyze the ISMIP6 results for high carbon emission scenarios, focusing on key glaciers around the Antarctic Ice Sheet, and we quantify their projected dynamic mass loss, defined here as mass loss through increased ice discharge into the ocean in response to changing oceanic conditions. We highlight glaciers contributing the most to sea level rise, as well as their vulnerability to changes in oceanic conditions. We then investigate the different sources of uncertainty and their relative role in projections, for the entire continent and for key individual glaciers. We show that, in addition to Thwaites and Pine Island glaciers in West Antarctica, Totten and Moscow University glaciers in East Antarctica present comparable future dynamic mass loss and high sensitivity to ice shelf basal melt. The overall uncertainty in additional dynamic mass loss in response to changing oceanic conditions, compared to a scenario with constant oceanic conditions, is dominated by the choice of ice sheet model, accounting for 52 % of the total uncertainty of the Antarctic dynamic mass loss in 2100. Its relative role for the most dynamic glaciers varies between 14 % for MacAyeal and Whillans ice streams and 56 % for Pine Island Glacier at the end of the century. The uncertainty associated with the choice of climate model increases over time and reaches 13 % of the uncertainty by 2100 for the Antarctic Ice Sheet but varies between 4 % for Thwaites Glacier and 53 % for Whillans Ice Stream. The uncertainty associated with the ice–climate interaction, which captures different treatments of oceanic forcings such as the choice of melt parameterization, its calibration, and simulated ice shelf geometries, accounts for 22 % of the uncertainty at the ice sheet scale but reaches 36 % and 39 % for Institute Ice Stream and Thwaites Glacier, respectively, by 2100. Overall, this study helps inform future research by highlighting the sectors of the ice sheet most vulnerable to oceanic warming over the 21st century and by quantifying the main sources of uncertainty.

Estimates of regional and global average sea level change remain a focus of climate change research. One complication in obtaining coherent estimates is that geodetic datasets measure different aspects of the sea level field. Satellite altimetry constrains changes in the sea surface height (SSH; or absolute sea level), whereas tide gauge data provide a measure of changes in SSH relative to the crust (i.e., relative sea level). The latter is a direct measure of changes in ocean volume (and the combined impacts of ice sheet melt and steric effects), but the former is not since it does not account for crustal deformation. Nevertheless, the literature commonly conflates the two estimates by directly comparing them. We demonstrate that using satellite altimetry records to estimate global ocean volume changes can lead to biases that can exceed 15%. The level of bias will depend on the relative contributions to sea level changes from the Antarctic and Greenland Ice Sheets. The bias is also more sensitive to the detailed geometry of mass flux from the Antarctic Ice Sheet than the Greenland Ice Sheet due to rotational effects on sea level. Finally, in a regional sense, altimetry estimates should not be compared to relative sea level changes because radial crustal motions driven by polar ice mass flux are nonnegligible globally.

We discuss the radar detection method as a probe for high-energy neutrino induced particle cascades in ice. In a previous work we showed that the radar detection techniqe is a promising method to probe the high-energy cosmic neutrino flux above PeV energies. This was done by considering a simplified cascade geometry and scattering model. In this article we discuss the scattering in more detail. We provide a model for the radar cross-section based on the induced plasma properties, and discuss the angular dependence of the scatter.

Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments-a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.

The Antarctic Ice Sheet (AIS) is out of equilibrium with the current anthropogenic‐enhanced climate forcing. Paleoenvironmental records and ice sheet models reveal that the AIS has been tightly coupled to the climate system during the past and indicate the potential for accelerated and sustained Antarctic ice mass loss into the future. Modern observations by contrast suggest that the AIS has only just started to respond to climate change in recent decades. The maximum projected sea level contribution from Antarctica to 2100 has increased significantly since the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report, although estimates continue to evolve with new observational and theoretical advances. This review brings together recent literature highlighting the progress made on the known processes and feedbacks that influence the stability of the AIS. Reducing the uncertainty in the magnitude and timing of the future sea level response to AIS change requires a multidisciplinary approach that integrates knowledge of the interactions between the ice sheet, solid Earth, atmosphere, and ocean systems and across time scales of days to millennia. We start by reviewing the processes affecting AIS mass change, from atmospheric and oceanic processes acting on short time scales (days to decades), through to ice processes acting on intermediate time scales (decades to centuries) and the response to solid Earth interactions over longer time scales (decades to millennia). We then review the evidence of AIS changes from the Pliocene to the present and consider the projections of global sea level rise and their consequences. We highlight priority research areas required to improve our understanding of the processes and feedbacks governing AIS change.

Abstract. We present a glacial isostatic adjustment (GIA) analysis for a joint ice and GIA history matching of the Antarctic Ice Sheet (AIS) since the last interglacial. This was achieved using the Glacial Systems Model (GSM) – which includes a glaciological ice sheet model asynchronously coupled to a viscoelastic Earth model. A large ensemble of 9293 simulations was conducted using the GSM. The history matching was against the AntICE2 database, which includes observations of past relative sea level, present-day (PD) vertical land motion, past ice extent, past ice thickness, borehole temperature profiles, PD geometry and surface velocity (Lecavalier et al., 2023). The 38 ensemble parameters of the GSM were history matched using Markov Chain Monte Carlo sampling that in turn employed Bayesian Artificial Neural Network emulators. The implications on the evolution of the AIS are detailed in a companion paper which predominantly focuses on the ice sheet component (Lecavalier and Tarasov, 2025). The history-matching analysis identified simulations from the full ensemble that are Not-Ruled-Out-Yet (NROY) by the data. This yielded a NROY sub-ensemble of simulations consisting of 82-members that approximately bound past and present GIA and sea-level change given uncertainties across the entire glacial system. The NROY Antarctic ice sheet chronologies and associated Earth viscosity models represent the Antarctic component of the “GLAC3-A” set of global ice sheet chronologies over the last glacial cycle. The NROY set of ice sheet histories in combination with a wide range of Earth rheologies is evaluated against available data. Data-model comparisons are shown against a subset of the AntICE2 database which directly constrains relative sea-level (RSL) change and bedrock displacement. This displays significant spatial variability in Antarctic GIA. The limited number of observational constraints contributes to wide inferred RSL bounds with max/min ranges up to 150 m during the Holocene. Finally, estimates of PD rates of bedrock displacement with tolerance intervals are presented and compared against those from previously published inferences. These previous Antarctic GIA studies are key inputs for geodetic studies of the contemporary AIS mass balance. We demonstrate that, by adequately exploring glacial and rheological uncertainties against a comprehensive database, past studies have underestimated Antarctic GIA uncertainties across large sectors, while other sectors are now more narrowly constrained. This history matching presents meaningful Antarctic GIA bounds of the rate of PD bedrock displacement with direct implications on mass balance estimates of the PD AIS.

Complex terrain is often characterized by mechanical sources, which force the initiation of convection in unstable atmospheric conditions, resulting in severe weather such as thunderstorms and hail, etc. With respect to the synoptic prevailing wind, the terrain can also cause heavy precipitation by converging flow and stationary rain bands. Rain gauges can provide a direct measure of accurate precipitation at a point station. However, low accessibility and high maintenance costs limit the ability to install high-resolution rain gauge networks in mountainous regions. Thus, quantitative precipitation estimation (QPE) through remote sensing using weather radar plays an important role in securing observation information on rainfall amounts in mountainous areas. In this study, we first analyzed the statistics of hazardous weather events retrieved from radar-based rainfall estimates over the Korean Peninsula according to complex topography. In order to analyze the frequency of occurrence of each type of hazardous weather such as torrential rain, hail, and snowfall according to orographic conditions, we used radar-based QPE. We investigated the correlation between topographic characteristics such as terrain altitude, wind direction, and downwind side and the frequency of occurrence and development of hazardous weather phenomena. We also examined the accuracy of QPE relating to rainfall mechanisms including radar echo top height for each warm and cold season. We analyzed the accuracy of QPEs according to various methods using radar reflectivity, dual-polarization parameters, and radar attenuation. We analyzed precipitation estimation error factors that may be caused by terrain shielding and high radar beam height in mountainous areas. We explored QPE errors based on radar beam height and echo intensity to improve the accuracy of QPE. Furthermore, in order to provide hazardous weather information specialized for the mountainous region, we have planned to develop an algorithm to estimate the probability of severe weather due to topographic characteristics by merging terrain altitude, atmospheric instability, and radar echo intensity by calculating Froude number using radar-based three-dimensional wind (Wind Synthesis System using Doppler Measurements, WISSDOM). In conjunction with the technology for calculating stationary precipitation information using radar echo image processing techniques, we aim to strengthen the ability to respond to dangerous weather by providing information on possible areas of heavy rain, snowfall, and extreme wind due to complex terrain.