Editorial for Special Issue “Advances in Satellite Altimetry and Its Application”

Denise Dettmering; Marcello Passaro; Alexander Braun

doi:10.3390/rs11242913

Using the Baltic Sea to advance algorithms to extract altimetry-derived sea-level data from complex coastal areas, featuring seasonal sea-ice

10.5194/egusphere-egu2020-6773 ◽

2020 ◽

Author(s):

Marcello Passaro ◽

Felix L. Müller ◽

Adili Abulaitijiang ◽

Ole B. Andersen ◽

Denise Dettmering ◽

...

Keyword(s):

Sea Ice ◽

Baltic Sea ◽

Sea Level ◽

Satellite Altimetry ◽

Coastal Areas ◽

Sea Surface ◽

Coastal Regions ◽

The Baltic Sea ◽

Mean Sea Surface ◽

The Baltic

The use of satellite altimetry at high latitudes and coastal regions is currently limited by the presence of seasonal sea ice coverage, and the proximity to the coast. The semi-enclosed Baltic Sea features seasonal coverage of sea-ice in the northern and coastal regions, and complex jagged coastlines with a huge number of small islands. However, as a semi-enclosed sea with a considerable extent, the Baltic Sea features a much-reduced tidal signal, both open- and coastal- waters, and an extensive multi-national network of tide-gauges. These factors maximise opportunities to drive improvements in sea-level estimations for coastal, and seasonal-ice regions.The ESA Baltic SEAL project, launched in April 2019, aims to exploit these opportunities. It is generating and validating a suite of enhanced multi-mission sea level products. Processing is developed specifically for coastal regions, with the objective of achieving a consistent description of the sea-level variability in terms of long-term trends, seasonal variations and a mean sea-surface. These will advance knowledge on adapting processing algorithms, to account for seasonal ice, and complex coastlines. Best practice approaches will be available to update current state-of-the-art datasets.In order to fulfill these goals, a novel altimeter re-tracking strategy has been developed. This enables the homogeneous determination of sea-surface heights for open-ocean, coastal and sea-ice conditions (ALES+). An unsupervised classification algorithm based on artificial intelligence routines has been developed and tailored to ingest data from all current and past satellite altimetry missions. This identifies radar echoes, reflected by narrow cracks within the sea-ice domain. Finally, the improved altimetry observations are gridded onto a triangulated surface mesh, featuring a spatial resolution greater than 1/4 degree. This is more suitable for utility for coastal areas, and use by coastal stakeholders.In addition to utilizing a wide range of altimetry data (Delay-Doppler and Pulse-Limited systems), the Baltic SEAL initiative harnesses the Baltic Seas unique characteristics to test novel geophysical corrections (e.g. wet troposphere correction), use the latest generation of regional altimetry datasets, and evaluate the benefits of the newest satellite altimetry missions. This presentation outlines the methodology and results achieved to date. These include estimations of a new regional mean sea surface, and insights into the trends of the sea level along the altimetry tracks with the longest records. The transfer of advances to other regions and sea-level initiatives are also highlighted.

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Advances in the Molecular Mechanisms of Abscisic Acid and Gibberellins Functions in Plants

International Journal of Molecular Sciences ◽

10.3390/ijms22116080 ◽

2021 ◽

Vol 22 (11) ◽

pp. 6080

Author(s):

Víctor Quesada

Keyword(s):

Abscisic Acid ◽

Molecular Mechanisms ◽

Original Research ◽

Special Issue ◽

Research Papers

In this special issue entitled, “Advances in the Molecular Mechanisms of Abscisic Acid and Gibberellins Functions in Plants”, eight articles are collected, with five reviews and three original research papers, which broadly cover different topics on the abscisic acid (ABA) field and, to a lesser extent, on gibberellins (GAs) research [...]

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Reactive Carbonyl Species and Protein Adducts: Identification Strategies, Biological Mechanisms and Molecular Approaches for Their Detoxification

Antioxidants ◽

10.3390/antiox10050690 ◽

2021 ◽

Vol 10 (5) ◽

pp. 690

Author(s):

Giancarlo Aldini ◽

Alessandra A. Altomare

Keyword(s):

Protein Adducts ◽

Special Issue ◽

Biological Mechanisms ◽

Research Papers ◽

Molecular Approaches ◽

Reactive Carbonyl Species ◽

Carbonyl Species ◽

Reactive Carbonyl

The Special issue is composed of 13 contributions: 9 research papers and 4 reviews [...]

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Introduction

History of Education Quarterly ◽

10.1017/s0018268000017969 ◽

1990 ◽

Vol 30 (4) ◽

pp. 487-492 ◽

Cited By ~ 2

Author(s):

Carl F. Kaestle

Keyword(s):

State Of The Art ◽

History Of Education ◽

The State ◽

Special Issue ◽

Research Papers ◽

History Of

The History of Education Quarterly has done it again. Despite many scholars' previous attempts to summarize the state of the art in historical studies of literacy, this special issue will now be the best, up-to-date place for a novice to start. It should be required reading for everyone interested in this subfield. The editors have enlisted an impressive roster of prominent scholars in the field, and these authors have provided us with an excellent array of synthetic reviews, methodological and theoretical discussions, and exemplary research papers.

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Crystal Plasticity

Crystals ◽

10.3390/cryst11010044 ◽

2021 ◽

Vol 11 (1) ◽

pp. 44

Author(s):

Wojciech Polkowski

Keyword(s):

Experimental Research ◽

Crystal Plasticity ◽

Review Paper ◽

Special Issue

The Special Issue on “Crystal Plasticity” is a collection of 25 original articles (including one review paper) dedicated to theoretical and experimental research works providing new insights and practical findings in the field of crystal plasticity-related topics [...]

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Mapping Mean Lake Surface from satellite altimetry and GPS kinematic surveys

10.5194/egusphere-egu21-14797 ◽

2021 ◽

Author(s):

Jean-Francois Crétaux ◽

Muriel Berge-Nguyen ◽

Stephane Calmant ◽

Sara Fleury ◽

Rysbek Satylkanov ◽

...

Keyword(s):

Lake Water ◽

Short Wavelength ◽

Satellite Altimetry ◽

Gravity Data ◽

Validation Dataset ◽

Large Set ◽

Lake Surface ◽

Laser Altimetry ◽

Geoid Model ◽

The Earth

Lake water height is a key variable in water cycle and climate change studies, which is achievable using satellite altimetry constellation. A method based on data processing of altimetry from several satellites has been developed to interpolate mean lake surface (MLS) over a set of 22 big lakes distributed on the Earth. It has been applied on nadir radar altimeters in Low Resolution Mode (LRM: Jason-3, Saral/AltiKa, CryoSat-2) in Synthetic Aperture Radar (SAR) mode (Sentinel-3A), and in SAR interferometric (SARin) mode (CryoSat-2), and on laser altimetry (ICESat). Validation of the method has been performed using a set of kinematic GPS height profiles from 18 field campaigns over the lake Issykkul, by comparison of altimetry&#8217;s height at crossover points for the other lakes and using the laser altimetry on ICESat-2 mission. The precision reached ranges from 3 to 7 cm RMS (Root Mean Square) depending on the lakes. Currently, lake water level inferred from satellite altimetry is provided with respect to an ellipsoid. Ellipsoidal heights are converted into orthom&#233;tric heights using geoid models interpolated along the satellite tracks. These global geoid models were inferred from geodetic satellite missions coupled with absolute and regional anomaly gravity data sets spread over the Earth. However, the spatial resolution of the current geoid models does not allow capturing short wavelength undulations that may reach decimeters in mountaineering regions or for rift lakes (Baikal, Issykkul, Malawi, Tanganika). We interpolate in this work the geoid height anomalies with three recent geoid models, the EGM2008, XGM2016 and EIGEN-6C4d, and compare them with the Mean Surface of 22 lakes calculated using satellite altimetry. Assuming that MLS mimics the local undulations of the geoid, our study shows that over a large set of lakes (in East Africa, Andean mountain and Central Asia), short wavelength undulations of the geoid in poorly sampled areas can be derived using satellite altimetry. The models used in this study present very similar geographical patterns when compared to MLS. The precision of the models largely depends on the location of the lakes and is about 18 cm, in average over the Earth. MLS can serve as a validation dataset for any future geoid model. It will also be useful for validation of the future mission SWOT (Surface Water and Ocean Topography) which will measure and map water heights over the lakes with a high horizontal resolution of 250 by 250 meters.

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The implications of selected processing methods on satellite altimetry derived sea ice thickness state and trends in the seasonal ice zone

10.5194/egusphere-egu21-12240 ◽

2021 ◽

Author(s):

Isolde Glissenaar ◽

Jack Landy ◽

Alek Petty ◽

Nathan Kurtz ◽

Julienne Stroeve

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Satellite Altimetry ◽

Region Of Interest ◽

The Arctic ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Baffin Bay ◽

The Impact

The ice cover of the Arctic Ocean is increasingly becoming dominated by seasonal sea ice. It is important to focus on the processing of altimetry ice thickness data in thinner seasonal ice regions to understand seasonal sea ice behaviour better. This study focusses on Baffin Bay as a region of interest to study seasonal ice behaviour.We aim to reconcile the spring sea ice thickness derived from multiple satellite altimetry sensors and sea ice charts in Baffin Bay and produce a robust long-term record (2003-2020) for analysing trends in sea ice thickness. We investigate the impact of choosing different snow depth products (the Warren climatology, a passive microwave snow depth product and modelled snow depth from reanalysis data) and snow redistribution methods (a sigmoidal function and an empirical piecewise function) to retrieve sea ice thickness from satellite altimetry sea ice freeboard data.The choice of snow depth product and redistribution method results in an uncertainty envelope around the March mean sea ice thickness in Baffin Bay of 10%. Moreover, the sea ice thickness trend ranges from -15 cm/dec to 20 cm/dec depending on the applied snow depth product and redistribution method. Previous studies have shown a possible long-term asymmetrical trend in sea ice thinning in Baffin Bay. The present study shows that whether a significant long-term asymmetrical trend was found depends on the choice of snow depth product and redistribution method. The satellite altimetry sea ice thickness results with different snow depth products and snow redistribution methods show that different processing techniques can lead to different results and can influence conclusions on total and spatial sea ice thickness trends. Further processing work on the historic radar altimetry record is needed to create reliable sea ice thickness products in the marginal ice zone.

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The origin of sea salt in snow on Arctic sea ice and in coastal regions

Atmospheric Chemistry and Physics ◽

10.5194/acp-4-2259-2004 ◽

2004 ◽

Vol 4 (9/10) ◽

pp. 2259-2271 ◽

Cited By ~ 87

Author(s):

F. Domine ◽

R. Sparapani ◽

A. Ianniello ◽

H. J. Beine

Keyword(s):

Time Series ◽

Sea Ice ◽

Ozone Depletion ◽

Sea Salt ◽

Sea Spray ◽

Snow Surface ◽

Coastal Regions ◽

Upward Migration ◽

Surface Snow ◽

Frost Flowers

Abstract. Snow, through its trace constituents, can have a major impact on lower tropospheric chemistry, as evidenced by ozone depletion events (ODEs) in oceanic polar areas. These ODEs are caused by the chemistry of bromine compounds that originate from sea salt bromide. Bromide may be supplied to the snow surface by upward migration from sea ice, by frost flowers being wind-blown to the snow surface, or by wind-transported aerosol generated by sea spray. We investigate here the relative importance of these processes by analyzing ions in snow near Alert and Ny-Ålesund (Canadian and European high Arctic) in winter and spring. Vertical ionic profiles in the snowpack on sea ice are measured to test upward migration of sea salt ions and to seek evidence for ion fractionation processes. Time series of the ionic composition of surface snow layers are investigated to quantify wind-transported ions. Upward migration of unfractionated sea salt to heights of at least 17cm was observed in winter snow, leading to Cl- concentration of several hundred µM. Upward migration thus has the potential to supply ions to surface snow layers. Time series show that wind can deposit aerosols to the top few cm of the snow, leading also to Cl- concentrations of several hundred µM, so that both diffusion from sea ice and wind transport can significantly contribute ions to snow. At Ny-Ålesund, sea salt transported by wind was unfractionated, implying that it comes from sea spray rather than frost flowers. Estimations based on our results suggest that the marine snowpack contains about 10 times more Na+ than the frost flowers, so that both the marine snowpack and frost flowers need to be considered as sea salt sources. Our data suggest that ozone depletion chemistry can significantly enhance the Br- content of snow. We speculate that this can also take place in coastal regions and contribute to propagate ODEs inland. Finally, we stress the need to measure snow physical parameters such as permeability and specific surface area to understand quantitatively changes in snow chemistry.

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Polyaxial Figures of the Moon

Journal of Geodetic Science ◽

10.2478/v10156-011-0013-z ◽

2011 ◽

Vol 1 (4) ◽

pp. 348-354 ◽

Cited By ~ 6

Author(s):

H. İz ◽

X. Ding ◽

C. Dai ◽

C. Shum

Keyword(s):

Center Of Mass ◽

The Moon ◽

Shape Parameters ◽

Axially Symmetric ◽

Laser Altimetry ◽

Additional Information ◽

All Solutions ◽

Ellipsoidal Model ◽

Lunar Topography ◽

Topography Model

Polyaxial Figures of the MoonThis study investigates various models to represent the gross geometric shape of the Moon. Asymmetric polyaxial geometric models-namely three-, four- and six-axial lunar figure - are compared and contrasted with the axially symmetric three-axis ellipsoidal model derived from Chang'e 1 and SELENE laser altimetry data. All solutions confirm a hydrostatically stable lunar shape shifted with respect to the lunar center of mass by topography. Model solutions with increasing complexity offer additional information about the regional properties of the lunar topography. Solution statistics suggest that axially symmetric lunar figures and their center of figure parameters can be replaced by an equivalent asymmetric lunar shape centered at the center of mass of the Moon. Thus, using only three shape parameters, one can derive an "egg" shape that better accommodates the true geometry of the Moon.

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KuKa altimeter mode data gathered during MOSAiC: scattering from snow covered sea ice and snow depth determination using dual-frequency and polarimetric approaches

10.5194/egusphere-egu21-16150 ◽

2021 ◽

Author(s):

Rosemary Willatt ◽

Julienne Stroeve ◽

Vishnu Nandan ◽

Rasmus Tonboe ◽

Stefan Hendricks ◽

...

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Satellite Altimetry ◽

Field Measurements ◽

Dual Band ◽

Altimetry Data ◽

Dual Frequency ◽

Sea Ice Thickness ◽

Ka Band ◽

Snow And Ice

Retrieving the thickness of sea ice, and its snow cover, on long time- and length-scales is critical for studying climate. Satellite altimetry has provided estimations of sea ice thickness spanning nearly three decades, and more recently altimetry techniques have provided estimations of snow depth, using dual-band satellite altimetry data. These approaches are based on&#160;assumptions about the main scattering surfaces of the radiation. The dominant scattering surface is often assumed to be the snow/ice interface at Ku-band frequencies and the air/snow interface at Ka-band and laser frequencies. It has previously&#160;been shown that these assumptions do not always hold, but field data to investigate the dominant scattering surfaces and investigate how these relate to the physical snow and ice characteristics were spatially and temporally limited. The MOSAiC expedition provided a unique opportunity to gather data using a newly-developed Ku- and Ka-band radar 'KuKa' deployed over snow-covered sea ice, along with coincident field measurements of snow and ice properties. We present transect data gathered with the instrument looking at nadir to demonstrate how the scattering characteristics vary spatially and temporally in the Ku- and Ka-bands, and discuss implications for interpretation of dual-frequency satellite radar altimetry data. We compare KuKa data with field measurements to demonstrate snow depth retrieval using Ku- and Ka-band data.

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