6 results on '"Izeboud, Maaike"'
Search Results
2. Damage detection on antarctic ice shelves using the normalised radon transform
- Author
-
Izeboud, Maaike and Lhermitte, Stef
- Published
- 2023
- Full Text
- View/download PDF
3. Where the White Continent Is Blue: Deep Learning Locates Bare Ice in Antarctica.
- Author
-
Tollenaar, Veronica, Zekollari, Harry, Pattyn, Frank, Rußwurm, Marc, Kellenberger, Benjamin, Lhermitte, Stef, Izeboud, Maaike, and Tuia, Devis
- Subjects
DEEP learning ,METEORITES ,ICE shelves ,ICE ,ICE sheets ,IMAGE segmentation ,SNOW cover ,CONTINENTS - Abstract
In some areas of Antarctica, blue‐colored bare ice is exposed at the surface. These blue ice areas (BIAs) can trap meteorites or old ice and are vital for understanding the climatic history. By combining multi‐sensor remote sensing data (MODIS, RADARSAT‐2, and TanDEM‐X) in a deep learning framework, we map blue ice across the continent at 200‐m resolution. We use a novel methodology for image segmentation with "noisy" labels to learn an underlying "clean" pattern with a neural network. In total, BIAs cover ca. 140,000 km2 (∼1%) of Antarctica, of which nearly 50% located within 20 km of the grounding line. There, the low albedo of blue ice enhances melt‐water production and its mapping is crucial for mass balance studies that determine the stability of the ice sheet. Moreover, the map provides input for fieldwork missions and can act as constraint for other geophysical mapping efforts. Plain Language Summary: While most of the continent of Antarctica is covered by snow, in some areas, ice is exposed at the surface, with a typical blue color. At lower elevations, blue ice enhances melt‐water production, which is important for studying the future of the ice sheet. Moreover, scientific teams frequently visit blue ice areas (BIAs) as they act as traps for meteorites and very old ice. In this study, we map the extent and the exact location of BIAs using various satellite observations. These diverse observations are efficiently combined in an artificial intelligence algorithm. We develop the algorithm so that it can learn to map blue ice even though existing training labels, which teach the algorithm what blue ice looks like, are imperfect. We quantify that the new map scores better on various performance metrics compared to the current most‐used blue ice map. Moreover, for the first time, we estimate uncertainties of the detection of blue ice. The map indicates that ca. 1% of the surface of Antarctica exposes blue ice and will be important for fieldwork missions and understanding surface processes leading to melt and potential sea level rise. Key Points: We map blue ice areas in Antarctica by combining multi‐sensor satellite observations in a convolutional neural networkBlue ice covers ca. 140,000 km2 (∼1%) of Antarctica, of which ca. 50% located in the grounding zoneOur map will improve mass balance estimates and studies on ice‐shelf stability, and will support searches for meteorites or old ice [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Improving surface melt estimation over the Antarctic Ice Sheet using deep learning: A proof of concept over the Larsen Ice Shelf
- Author
-
Hu, Zhongyang, Kuipers Munneke, Peter, Lhermitte, Stef, Izeboud, Maaike, Van Den Broeke, Michiel, Sub Dynamics Meteorology, Marine and Atmospheric Research, Sub Dynamics Meteorology, and Marine and Atmospheric Research
- Subjects
QE1-996.5 ,Science & Technology ,IMPACT ,Geology ,CLIMATE ,Environmental sciences ,Geography, Physical ,Physical Geography ,Physical Sciences ,GE1-350 ,Geosciences, Multidisciplinary ,PENINSULA ,MELTWATER ,Water Science and Technology ,Earth-Surface Processes - Abstract
Accurately estimating the surface melt volume of the Antarctic Ice Sheet is challenging and has hitherto relied on climate modeling or observations from satellite remote sensing. Each of these methods has its limitations, especially in regions with high surface melt. This study aims to demonstrate the potential of improving surface melt simulations with a regional climate model by deploying a deep learning model. A deep-learning-based framework has been developed to correct surface melt from the regional atmospheric climate model version 2.3p2 (RACMO2), using meteorological observations from automatic weather stations (AWSs) and surface albedo from satellite imagery. The framework includes three steps: (1) training a deep multilayer perceptron (MLP) model using AWS observations, (2) correcting Moderate Resolution Imaging Spectroradiometer (MODIS) albedo observations, and (3) using these two to correct the RACMO2 surface melt simulations. Using observations from three AWSs at the Larsen B and C ice shelves, Antarctica, cross-validation shows a high accuracy (root-mean-square error of 0.95 mm w.e. d−1, mean absolute error of 0.42 mm w.e. d−1, and a coefficient of determination of 0.95). Moreover, the deep MLP model outperforms conventional machine learning models and a shallow MLP model. When applying the trained deep MLP model over the entire Larsen Ice Shelf, the resulting corrected RACMO2 surface melt shows a better correlation with the AWS observations for two out of three AWSs. However, for one location (AWS 18), the deep MLP model does not show improved agreement with AWS observations; this is likely because surface melt is largely driven by factors (e.g., air temperature, topography, katabatic wind) other than albedo within the corresponding coarse-resolution model pixels. Our study demonstrates the opportunity to improve surface melt simulations using deep learning combined with satellite albedo observations. However, more work is required to refine the method, especially for complicated and heterogeneous terrains.
- Published
- 2021
5. Evaluating and improving ice sheet clouds, radiation, and precipitation in the Community Earth System Model
- Author
-
Lenaerts, Jan, Camron, Michael D., Kay, Jennifer E., van Kampenhout, Leo, Gettelman, Andrew, L'Ecuyer, Tristan, Souverijns, Niels, Izeboud, Maaike, and Lhermitte, S.L.M.
- Abstract
Clouds exert a pivotal control on the mass balance of the Greenland and Antarctic Ice Sheet and therefore their contribution to global sea level. Clouds transport moisture onto the marginal ice sheet, where steep topographic gradients force the air to rise and cool, inducing strong orographic precipitation and leaving the interior ice sheet dry (polar desert). Clouds further regulate the radiation balance at the surface and, consequently, surface melt. Depending on their frequency, phase, and structure, clouds not only mute incoming solar radiation but also enhance longwave radiation at the surface. With the advent of novel observations from space (CloudSat-CALIPSO) and in the field, we now have tools to start evaluating the representation of clouds, precipitation, and ice sheet surface radiation in climate models. Here we evaluate the Community Earth System Model version 1 (CESM1(CAM5)) to represent (1) precipitation frequency and phase, using a CALIPSO cloud simulator; (2) cloud radiative effect comparing to a CloudSat-CALIPSO based product; and (3) snowfall amounts and surface mass balance, comparing to CloudSat, in-situ observations, and regional climate model results. After discussing outstanding cloud biases in CESM1(CAM5), we present our efforts to reduce these in the recently released version 2 (CESM2). We show that clouds are considerably better represented in CESM2, leading to improvements in surface radiation, melt, and surface mass balance, although biases in precipitation phase persist. Our work demonstrates the need for high-quality, long-term observations of clouds and their effect on the ice sheet surface to enable continued climate model improvement.
- Published
- 2018
6. Response of Greenland and Antarctic Ice Sheet to cloud radiative forcing.
- Author
-
Izeboud, Maaike, Lhermitte, Stef, Lenaerts, Jan, Van Tricht, Kristof, Van Lipzig, Nicole, and Wever, Nander
- Subjects
- *
ICE sheets , *GREENLAND ice , *RADIATIVE forcing , *ANTARCTIC ice , *ICE clouds , *ICE shelves , *SNOW - Abstract
The role of clouds on the surface mass balance of ice sheets remains a point of debate as there is no scientific consensus on the role of the cloud radiative effect (CRE) on the two major ice sheets. For the Greenland Ice Sheet, for example, conflicting studies argue either that clouds reduce surface melt through their radiative effect by blocking short-wave radiation (cloud cooling) or enhance surface melt by reducing meltwater refreezing (cloud warming). For the Antarctic Ice Sheet, on the other hand, the impact of the CRE effects on the ice sheet remain poorly quantified, although it can play a major role on the melt processes on ice shelves.To assess the impact of the CRE on surface snow and firn conditions on both ice sheets, simulations have been performed with SNOWPACK, a physically-based snow model forced with and without cloud radiative forcing. For this purpose, a state-of-the-art hybrid dataset has been created to represent the cloud forcing on the surface mass balance. This hybrid data set is a combination of CloudSat-CALIPSO satellite observations and data from the regional climate model, RACMO2.3. The combination of both data sets results in an observation-based forcing dataset with higher temporal resolution than the satellite observations can provide. Simulations are performed such that the response of the firn can be separated in a short-term and long-term component.Results show that the seasonal variation of the CRE is positive throughout the year, which implies a net cloud warming. Additionally, the simulations highlight that cloud cooling and cloud warming occur on different time scales: the first being a more direct, short-term effect and the latter having a long-term effect by initiating a feedback response that changes firn conditions. The long-term response of the firn to the CRE is shown to be dominant in summer, enhancing meltwater production and runoff by initializing a melt-albedo feedback.The long-term CRE impact on firn conditions during the melt season highlights the importance of the (initial) firn conditions when performing cloud radiation studies. It calls for the need of either detailed information of the firn surface layers or the inclusion of a snow-model that can accurately model firn response in such studies. [ABSTRACT FROM AUTHOR]
- Published
- 2019
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.