Mònica Roca

isardSAT

A trihedral corner reflector has been used to evaluate the capability of passive reflectors to calibrate radar altimeters such as the Poseidon-4 altimeter on board Sentinel-6A. The reflector location, placed on the top of a mountain ridge and about 4-km off-nadir of the Sentinel-6A subsatellite track, allows capturing echoed signals with a Signal-t...

Presentation of the approach and validation of a Coastal Processor, over different Areas around the globe and using 4 different altimetry missions. A refinement of the algorithms has been conducted in the last years, in order to make it robust, reliable, fast, and easy to implement.

CryoSat-2 is the first satellite mission carrying a high pulse repetition frequency radar altimeter with interferometric capability on board. Across track interferometry allows the angle to the point of closest approach to be determined by combining echoes received by two antennas and knowledge of their orientation. Accurate information of the plat...

The Sentinel-3 Mission Performance Centre (S3MPC) is tasked by the European Space Agency (ESA) to monitor the health of the Copernicus Sentinel-3 satellites and ensure a high data quality to the users. This paper deals exclusively with the effort devoted to the altimeter and microwave radiometer, both components of the Surface Topography Mission (S...

Swath mode processing of CryoSat-2 Synthetic Aperture Radar Interferometric (SARIn) mode has been used to monitor elevation of areas with complex topography such as over ice sheet and ice cap margins. Swath processing relies on an accurate measure of the angle of arrival of the measured echo and, therefore, requires custom strategies in order to re...

Satellite altimeters have been used to monitor river and reservoir water levels, from which water storage estimates can be derived. Inland water altimetry can, therefore, play an important role in continental water resource management. Traditionally, satellite altimeters were designed to monitor homogeneous surfaces such as oceans or ice sheets, re...

The launch of Sentinel-3A in February 2016 represented the beginning of a new long-term series of operational satellite radar altimeters, which will provide Delay-Doppler altimetry measurements over ice sheets for decades to come. Given the potential benefits that these satellites can offer to a range of glaciological applications, it is important...

Satellite altimeters have been used to monitor river and reservoir water levels, from which water storage estimates can be derived. Inland water altimetry can therefore play an important role in continental water resource management. Traditionally, satellite altimeters were designed to monitor homogeneous surfaces such as oceans or ice sheets, resu...

The Sentinel-6/Jason-CS mission is the latest successor mission of the Jason altimetry mission series and part of the ESA Copernicus Programme. Its main objective is to continue the long term climate data record of sea level measurements that started in 1992 with the Topex/Poseidon mission. Sentinel-6 will operate from 2020 onwards in the same refe...

Sentinel-3 is the Earth observation satellite mission designed to ensure the long-term collection and operational delivery of high-quality measurements of, among others, the sea surface topography. Post-launch calibration and validation of the satellite measurements is a prerequisite to achieve the desired level of accuracy and ensure the return of...

On 16th February 2016, the launch of the Sentinel-3A satellite marked the first step towards a new era of operational Delay-Doppler altimetry over ice sheets. Given the provision of these novel altimeters for decades to come, and the long-term benefits they can offer to a range of glaciological applications, it is important to establish their capac...

The SHAPE Processor implements all of the steps necessary to derive rivers and lakes water levels and discharge from Delay-Doppler Altimetry and perform their validation against in situ data. The processor uses FBR CryoSat-2 and L1A Sentinel-3A data as input and also various ancillary data (proc. param., water masks, L2 corrections, etc.), to produ...

This article explores the modification and inclusion of different algorithms within an in-house Delay-Doppler processor (DDP) chain in order to understand their potentiality and the related impact in terms of geophysical retrievals’ precision, when operating the synthetic aperture radar (SAR) mode of CryoSat-2 mission over open ocean. To do so, a f...

The CryoSat-2 (CS-2) mission is an altimetric mission designed to meet the measurement requirements for ice-sheet elevation and sea-ice ‘freeboard’. In addition to Cryosphere applications, this mission is of great interest to the Hydrosphere and Oceanographic communities since it allows for quantitative assessment of expected enhanced altimetric ca...

Transponders are commonly used to calibrate absolute range from conventional altimeter waveforms because of their characteristic point target radar reflection. The waveforms corresponding to the transponder distinguish themselves from the other waveforms resulting from natural targets, in power and shape. ESA deployed a transponder available for th...

Over the past 20 years, satellite radar altimetry has shown its ability to revolutionise our understanding of the ocean and climate. Previously, these advances were largely limited to ice-free regions, neglecting large portions of the Polar Regions. Launched in 2010, the European Space Agency’s (ESA) polar-orbiting CryoSat satellite was specificall...

For more than 25 years, satellite radar altimetry has provided continuous information on the state of the cryosphere and on its contribution to global sea-level rise. The technique typically delivers maps of ice-sheet elevation and elevation change with 3–10 km spatial resolution and seasonal to monthly temporal resolution. Here we show how the int...

The Sentinel-3A altimeter calibration monitoring results are here described, updated to 2017 Sept .

During the last decade the radar altimetry has entered its golden age as demonstrated by the different number of missions (Jason-3, CryoSat-2, SARAL/Altika, Sentinel-3) currently operating and the forthcoming Sentinel-6. The latter is an operational oceanography programme of two satellites that will ensure continuity to the Jason series of operatio...

Satellite altimetry has been used extensively in the past few decades to observe changes affecting large and remote regions covered by land ice such as the Greenland and Antarctic ice sheets. Glaciers and ice caps have been studied less extensively due to the limitation of altimetry over complex topography. However, their role in current sea-level...

During the last decade the radar altimetry has entered in its golden age as demonstrated by the different number of missions (Jason-3, CryoSat-2, SARAL/Altika, Sentinel-3a) currently operating and continuity missions planned for the near future (Sentinel-3b, Sentinel-6). The relatively new operational SAR mode in CryoSat-2 and Sentinel-3 missions,...

This poster presents the range and datation results using the Crete transponder for the first 23 cycles. This work is been carried out within the Sentinel-3 Mission Performance Center activity S3MPC.

Sentinel-3A, launched in February 2016, is part of ESA's long-term commitment to climate monitoring from space. Its suite of instruments for measuring surface topography includes a Microwave Radiometer (MWR) and SRAL, the first delay-Doppler instrument to provide global coverage. SRAL promises fine spatial resolution and reduced noise levels that s...

Poster briefly summarising the activities to assess the performance of SRAL (the Sentinel-3A altimeter)

Twelve years (1991-2003) of ERS-1 and ERS-2 altimetry data have been reprocessed within the European Space Agency (ESA) reprocessing altimeter products for ERS (REAPER) project using an updated, modern set of algorithms and auxiliary models. The reprocessed data set (identified as RP01) has been cross-calibrated against the reprocessed ENVISAT V2.1...

The ESA Sentinel-3 satellite, within the Copernicus programme, will be the second satellite to operate a SAR mode altimeter. The Sentinel 3 Synthetic Aperture Radar Altimeter (SRAL) is based on the heritage from Cryosat-2, but will be complemented by a Microwave Radiometer (MWR) to provide a wet troposphere correction, and will operate at Ku and C-...

The CryoSat mission is designed to determine fluctuations in the mass of the Earth’s land and the marine ice fields. Its primary payload is a radar altimeter that operates in different modes optimised depending on the kind of surface: Low resolution mode (LRM), SAR mode (SAR) and SAR interferometric mode (SARin). This radar is named SIRAL: Syntheti...

The ESA Sentinel-3 satellite, launched in February 2016 as a part of the Copernicus programme, is the second satellite to operate a SAR mode altimeter. The Sentinel 3 Synthetic Aperture Radar Altimeter (SRAL) is based on the heritage from Cryosat-2, but this time complemented by a Microwave Radiometer (MWR) to provide a wet troposphere correction,...

Accurate monitoring of the sea level is required to better understand its variability and changes. Sea level is one of the Essential Climate Variables (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. It aims at providing a long-term homogeneous and accurate sea level record. The needs and feedback of the climate rese...

The Sentinel-3A is the most recent altimetric mission of a long historical series. It is well known the crucial importance of the instrumental calibration when processing the altimeter data , in order to produce reliable and accurate L2 geophysical retrievals, such as sea surface height, significant wave height, or wind speed over the oceans. isard...

the core of this presentation intends to show the potential capabilities of the ACDC method when integrate in the CryoSat-2 and Sentinel-3 processing baselines, comparing the retrieved geophysical parameters with the conventional SAR processing baselines for both missions over FBR CryoSat-2 data on several tracks over open-ocean. Taking into accoun...

This comparative study is based on the validation of the different in-house developed DDP processing approaches through the inversion of the geophysical parameters (SSH, SWH and sigma0), exploiting an in- house implementation of the Chris et al 2015 analytical SAR retracker. This analytical retracker is adapted hand- in-hand to the L1B processing i...

The advent of SAR altimetry has prompted a radical rethinking of the amount of information contained in the altimetric echoes, and has brought along advanced processing techniques that exploit the Doppler information in the signal. Many groups around the world are at work to refine aspects of the processing with the aim of an improved (i.e. more ac...

SIRAL Range, Datation and Interferometric Phase results from 2010-2016 using data over the Svalbard Transponder.

The Poseidon-3 altimeter onboard Jason-2 includes a significant new capability with respect to its predecessors, an open-loop (DIODE/DEM) tracker mode. This innovative mode is capable of successfully tracking the backscat-ter signal over rapidly varying terrains, and thus overcomes one of the limitations of the closed-loop Poseidon-2 tracker on boa...

Reference and repeat-observations of Glacier, Ice Caps and Ice Sheet Margin topography are critical to identify changes in ice thickness, provide estimates of mass gain or loss and thus quantify the contribution of the cryosphere to sea level change. The lack of such sustained observations was identified in the Integrated Global Observing Strategy...

Sea level is a very sensitive index of climate change and variability. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level variability and changes implies an accurate monitoring of the sea level variable at climate scales, in addition to understanding the ocean variability and the exchanges b...

Sea level is a very sensitive index of climate change and variability. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level variability and changes implies an accurate monitoring of the sea level variable at climate scales, in addition to understanding the ocean variability and the exchanges b...

The universal altimetry toolbox, BRAT (Broadview Radar Altimetry Toolbox), already capable of dealing with past and current altimetry missions’ data, incorporates now the capability of reading the upcoming Sentinel-3 L1 and L2 products. ESA promotes and supplies this new feature, supporting users of the future Sentinel-3 SAR Altimetry Mission.

Over the past 20 years, satellite radar altimetry has shown its ability to revolutionize our understanding of the ocean and climate. These advances were mainly limited to ice-free regions, leaving aside large portions of Polar Regions. Launched in 2010, the polar-orbiting CryoSat Satellite was designed to measure the changes in the thickness of pol...

A new method of forming the synthetic aperture radar altimeter multilook backscattered power waveform is proposed for application over water. The method compensates the waveform for both variations in amplitude and dilation in range, which are caused by the geometry of the observation and the signal processing chain of the instrument. Using Cryosat...

SAR Altimetry algorithm improvements applied to the Sentinel-6/Jason-CS mission

The Poseidon-3 altimeter onboard Jason-2 includes a significant new capability with respect to its predecessors, an open-loop (DIODE/DEM) tracking mode that allows for maintaining data acquisition over coastal and inland zones. In a further enhancement, Jason-3 and Sentinel-3 will be capable of switching to this innovative mode for selected regions...

Sentinel-3A is scheduled for launch in Oct. 2015, with Sentinel-3B to follow 18 months later. Together these missions are to take oceanographic remote-sensing into a new operational realm. To achieve this a large number of processing, calibration and validation tasks have to be applied to their data in order to assess for quality, absolute bias, sh...

The ESA Data User Element (DUE) funded GlobCurrent project (http://www.globcurrent.org) aims to: (i) advance the quantitative estimation of ocean surface currents from satellite sensor synergy; and (ii) demonstrate impact in user-led scientific, operational and commercial applications that, in turn, will improve and strengthen the uptake of satelli...

The main payload of the ESA Earth Explorer CryoSat satellite is a Ku band pulse-width limited radar altimeter, operating in 3 different modes function of a mask of geographical zones.Over the ocean and ice sheet interiors, CryoSat mainly operates like a conventional pulse-limited radar altimeter whereas over sea ice, coherently transmitted echoes a...

Sea level is one of the 50 Essential Climate Variables (ECVs) listed by the Global Climate Observing System (GCOS) in climate change monitoring. In the past two decades, sea level has been routinely measured from space using satellite altimetry techniques. In order to address a number of important scientific questions such as "Is sea level rise acc...

ESA's first Remote Sensing Satellite: ERS-1 was launched on July 17, 1991 and operated until June 1996, completing one year of parallel operation (Tandem Mission) with ERS-2. Launched in April 1995, ERS-2 has operated for over 14 years with all instrumentation still working well despite the loss of the on-board tape recorders and the transition to...

Sea level is one of the 50 Essential Climate Variables (ECVs) listed by the Global Climate Observing System (GCOS) in climate change monitoring. In the last two decades, sea level has been routinely measured from space using satellite altimetry techniques. In order to address a number of important scientific questions such as: "Is sea level rise ac...

The REAPER reprocessing activity has produced a homogeneous, improved ERS altimetry dataset, processed with a uniform set of algorithms and models, and cross-calibrated with ENVISAT. Many improvements have been made to the L1, L2 and Calibration processing of the ERS data. These improvements have largely derived from the processing developed for EN...

Although the history of spaceborne altimeters goes back to the early seventies, the absolute calibration of the backscattering coefficient has never been deeply investigated. This information has been primarily used to infer the wind speed via an empirical model, and the intercalibration among different satellite altimeters has revealed to be suita...

The ESA Cryosat-2 mission is the first space mission to carry a radar altimeter that can operate in Synthetic Aperture Radar (SAR) mode. Although the prime objective of the Cryosat-2 mission is dedicated to monitoring land and marine ice, the SAR mode capability of the Cryosat-2 SIRAL altimeter also presents the opportunity of demonstrating signifi...

Sea level is a very sensitive index of climate change and variability. As the ocean warms in response to global warming, sea waters expand and, as a result, sea level rises. When mountain glaciers melt in response to increasing air temperature, sea level rises because more freshwater glacial runoff discharges into the oceans. Similarly, ice mass lo...

Two Decades of Global and Regional Sea Level Observations from the ESA Climate Change Initiative Sea Level Project G. Larnicol1, A. Cazenave2, Y. Faugère1, M. Ablain1, J. Benveniste13, B.M. Lucas13, S.Dinardo13, J.Johannessen3, D. Stammer4, G. Timms5, P. Knudsen6, P. Cipollini7, M. Roca8, S. Rudenko9, J. Fernandes10, M. Balmaseda11, T. Guinle12 1...

ESA's first Remote Sensing Satellite: ERS-1 was launched on July 17, 1991 and operated until June 1996, completing one year of parallel operation (Tandem Mission) with ERS-2. Launched in April 1995, ERS-2 has operated for over 16 years with all instrumentation still working well despite the loss of the on-board tape recorders and the transition to...

The altimeter on-board EnviSat, RA-2, incorporates many new features, in particular a new 'model' free tracker (MFT) and automatic resolution selection logic (RSL) to switch between three bandwidths (320MHz, 80MHz, 20MHz). Autonomous switching between different bandwidths is achieved by an on-board algorithm (RSL), using information from the return...

The EnviSat satellite embarks an innovative radar altimeter, the RA-2 which represents a new generation of radar altimeters compared to previous instruments such as the European Remote Sensing Satellite (ERS) altimeters and The Ocean Topography Experiment/Poseidon. This is due to its integration of many new features. In particular, the RA-2 is the...

River bank protection is a costly but essential component in river management. Outer banks in river bends are most vulnerable to scour and erosion. Previous laboratory experiments illustrated that a well-designed horizontal foundation of a vertical outer bank protruding into the cross section, called a footing, can reduce the scour depth and thereb...

Radar altimetry measurements have been traditionally used to monitor ocean surfaces and ice caps. Previous studies have shown the potentialities of radar altimetry to monitor land surfaces at the global scale. However, radar altimetry applications over continental surfaces remain relatively underdeveloped. The aim of this study is to use Envisat RA...

Malaria is one of the major public health challenges undermining development in the world. The aim of MalarSat Project is to provide a malaria risks infection maps at global scale using Earth Observation data to support and prevent epidemic episodes. The proposed service for creating malaria risk maps would be critically useful to improve the effic...

Starting in February 2006, the ranges measured by the Envisat RA-2 altimeter have been biased significantly for long periods of time. The range bias is characterised by a relatively constant offset of about 5.6 meters, and an additional 1-cpr non-harmonic variation around the orbit with an amplitude of about 10-20 cm.

The RA-2 in its nominal operation provides averaged waveforms at the rate of 18 Hz (one averaged waveform over 100 individual echoes, every 0.0557 seconds). It has also the capability to provide limited bursts of individual, unaveraged echo sample data in phase (I) and quadrature (Q), at the full PRF rate. In this concept the full-rate data are sto...

It has been demonstrated that for the proper exploitation for the S-Band data, a calibration is required. Pildo Labs and UCL are presenting here a cross-calibration of the S-band range against the K u- band range, performed by comparing the S-band echoes against the Ku-band echoes over the salar Uyuni. This target has been chosen because of the ve...

The main instrument of CRYOSAT will be the SAR Interferometric Radar Altimeter (SIRAL). Two different softwares have been developed to calibrate SIRAL level 1A and level 1B data respectively with the use of a geolocated transponder. Level 1A data consist of bursts of complex, time domain echoes after internal calibration corrections while level 1B...

A unique feature of the ENVISAT RA-2 is to provide bursts of individual, unav eraged Ku band echo s ample data in phase (I) and quadrature (Q), at the full rate 1800 Hz. This data offers a unique possibility to assess the full capabilities of altimeter measurements. Both technically and scientifically, much can be expected fro m these bursts o f in...

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A unique feature of the ENVISAT RA-2 is to provide bursts of individual, unaveraged Ku band echo sample data in phase (I) and quadrature (Q), at the full rate 1800 Hz. This data offers a unique possibility to assess the full capabilities of altimeter measurements. Both technically and scientifically, much can be expected from these bursts of indivi...