Ablain Michaël

Ablain Michaël
Collecte Localisation Satellites | CLS · Space Oceanography Division

Project Engineer

About

101
Publications
23,142
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Introduction
I'm responsible of the altimetry validation activities at CLS (Toulouse, France). This work aims at analyzing the performances of all the altimeter missions especially over ocean. My studies allows us to better know the error budget of altimeter mission at different spatial and temporal scales, in particular for the global and regional Mean Sea Level evolution.
Additional affiliations
June 1999 - present
Collecte Localisation Satellites
Position
  • Project Engineer / Data Analysis & Validation
Description
  • I'm the head of department Performance Mission and Climate in Space Oceanography Division at CLS.

Publications

Publications (101)
Article
Full-text available
An instrumental drift in the point target response (PTR) parameters has been detected on the Copernicus Sentinel-3A altimetry mission. It will affect the accuracy of sea level sensing, which could result in errors in sea level change estimates of a few tenths of a millimeter per year. In order to accurately evaluate this drift, a method for detecti...
Preprint
We investigate the continuity and stability of GRACE and GRACE Follow-On satellite gravimetric missions by assessing the ocean mass budget at global scale over 2005–2020, focusing on the last years of the record (2015–2020) when GRACE and GRACE Follow-On faced instrumental problems. For that purpose, we compare the global mean ocean mass estimates...
Poster
Full-text available
Given the major role of the Atlantic Ocean in the climate system, it is essential to characterize the temporal and spatial variations of its heat content. The 4DATLANTIC-OHC project (2021-2023) aims at developing and testing space geodetic methods to estimate the local ocean heat content (OHC) changes over the Atlantic Ocean from satellite altimetr...
Preprint
We present the latest released of the Global Mean Sea Level (GMSL) record produced by the French space agency CNES and distributed on the AVISO+ website. This dataset is based on reprocessed along-track data, so-called L2P 21, of the reference missions Topex-Poseïdon, Jason-1/-2 and -3. The L2P 21 CNES/AVISO GMSL record covers the period January-19...
Poster
Full-text available
On behalf of the European Commission, the European Environment Agency has commissioned the development and real-time production of the Copernicus High Resolution Snow & Ice products (HRSI), including a snow cover component to address these needs. In particular, this service provides a canopy-adjusted fractional snow cover (FSC) at 20 m resolution...
Article
Full-text available
The Earth energy imbalance (EEI) at the top of the atmosphere is responsible for the accumulation of heat in the climate system. Monitoring the EEI is therefore necessary to better understand the Earth's warming climate. Measuring the EEI is challenging as it is a globally integrated variable whose variations are small (0.5–1 W m−2) compared to the...
Article
Full-text available
It is essential to monitor accurately current sea level changes to better understand and project future sea level rise (SLR). This is the basis to support the design of adaptation strategies to climate change. Altimeter sea level products are operationally produced and distributed by the E.U. Copernicus services dedicated to the marine environment...
Preprint
Full-text available
An instrumental drift in the Point Target Response (PTR) parameters has been detected on the Copernicus Sentinel-3A (S3A) altimetry mission. It could have an impact on sea level rise of a few tenths of mm yr−1. In order to accurately evaluate this drift, a method for detecting global and local mean sea level relative drifts between two altimetry mi...
Article
Full-text available
The High Resolution Snow & Ice Monitoring Service was launched in 2020 to provide near-real-time, pan-European snow and ice information at 20 m resolution from Sentinel-2 observations. Here we present an evaluation of the snow detection using a database of snow depth observations from 1764 stations across Europe over the hydrological year 2016–2017...
Article
Full-text available
In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and mo...
Preprint
Full-text available
The Earth energy imbalance (EEI) at the top of the atmosphere is responsible for the accumulation of heat in the climate system. Monitoring the EEI is therefore necessary to better understand the Earth’s warming climate. Measuring the EEI is challenging as it is a globally integrated variable whose variations are small (0.5–1 W m−2) compared to the...
Preprint
Full-text available
The High Resolution Snow & Ice Monitoring Service was launched in 2020 to provide near real time, pan-European snow and ice information at 20 m resolution from Sentinel-2 observations. Here we present an evaluation of the snow detection using a database of snow depth observations from 1764 stations across Europe over the hydrological year 2016–2017...
Article
Full-text available
Satellite altimetry missions provide a quasi-global synoptic view of sea level variations over more than 25 years and provide regional sea level (SL) indicators such as trends and accelerations. Estimating realistic uncertainties on these quantities is crucial to address current climate science questions. While uncertainty estimates are available f...
Poster
Full-text available
Community Paper - Frontiers of Marine Science https://www.frontiersin.org/articles/10.3389/fmars.2019.00432/full
Poster
Full-text available
Monitoring and Predicting Regional to Coastal Sea Level: Towards Comprehensive Observing and Modeling Systems
Article
Full-text available
The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4–1 Wm–2). This imbalance is coined Earth’s Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the...
Article
Full-text available
Satellite altimetry missions now provide more than 25 years of accurate, continuous and quasi-global measurements of sea level along the reference ground track of TOPEX/Poseidon. These measurements are used by different groups to build the Global Mean Sea Level (GMSL) record, an essential climate change indicator. Estimating a realistic uncertainty...
Article
Full-text available
A major challenge for managing impacts and implementing effective mitigation measures and adaptation strategies for coastal zones affected by future sea level (SL) rise is our limited capacity to predict SL change at the coast on relevant spatial and temporal scales. Predicting coastal SL requires the ability to monitor and simulate a multitude of...
Article
Full-text available
Satellite altimetry missions now provide more than 25 years of accurate, continuous and quasi-global measurements of sea level along the reference ground track of TOPEX/Poseidon. These measurements are used by different groups to build the Global Mean Sea Level (GMSL) record, an essential climate change indicator. Estimating a realistic uncertainty...
Article
Since the beginning of the altimeter mission TOPEX/Poseidon (T/P), followed by Jason-1 and Jason-2 on similar orbits, and many other missions on different orbits (ERS, EnviSat, etc.), mean sea level (MSL) products became essential for the comprehension of global ocean circulation. Since early in the T/P mission, a suspicious signal, having a period...
Article
Full-text available
Sea level is a very sensitive index of climate change since it integrates the impacts of ocean warming and ice mass loss from glaciers and the ice sheets. Sea level has been listed as an essential climate variable (ECV) by the Global Climate Observing System (GCOS). During the past 25 years, the sea level ECV has been measured from space by differe...
Article
Full-text available
Sea Level is a very sensitive index of climate change since it integrates the impacts of ocean warming and ice mass loss from glaciers and the ice sheets. Sea Level has been listed as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). During the past 25 years, the sea level ECV has been measured from space by differe...
Article
Full-text available
Sea level is an essential climate variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural cl...
Article
Full-text available
The question of how to derive and present uncertainty information in climate data records (CDRs) has received sustained attention within the European Space Agency Climate Change Initiative (CCI), a programme to generate CDRs addressing a range of essential climate variables (ECVs) from satellite data. Here, we review the nature, mathematics, practi...
Chapter
Since the beginning of the 1990s, sea level is routinely measured using high-precision satellite altimetry. Over the past \(\sim \)25 years, several groups worldwide involved in processing the satellite altimetry data regularly provide updates of sea level time series at global and regional scales. Here we present an ongoing effort supported by the...
Chapter
Full-text available
Results of the sea-level budget in the high latitudes (up to \(80^{\circ }\)N) and the Arctic Ocean during the satellite altimetry era. We investigate the closure of the sea-level budget since 2002 using two altimetry sea-level datasets based on the Envisat waveform retracking: temperature and salinity data from the ORAP5 reanalysis, and Gravity Re...
Article
Full-text available
Sea level is an Essential Climate Variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural cl...
Article
We revisit the global mean sea level (GMSL) budget during the whole altimetry era (January 1993- December 2015) using a large number of data sets. The budget approach allows quantifying the TOPEX A altimeter drift (amounting 1.5 +/- 0.5 mm/yr over 1993-1998). Accounting for this correction and using ensemble means for the GMSL and components leads...
Preprint
Full-text available
Climate data records (CDRs) derived from Earth observation (EO) should include rigorous uncertainty information, to support application of the data in policy, climate modelling and numerical weather prediction reanalysis. Uncertainty, error and quality are distinct concepts, and CDR products should follow international norms for presenting quantifi...
Article
Full-text available
Results of the sea-level budget in the high latitudes (up to 80°N) and the Arctic Ocean during the satellite altimetry era. We investigate the closure of the sea-level budget since 2002 using two altimetry sea-level datasets based on the Envisat waveform retracking: temperature and salinity data from the ORAP5 reanalysis, and Gravity Recovery And C...
Article
Full-text available
Since the beginning of the 1990s, sea level is routinely measured using high-precision satellite altimetry. Over the past ~25 years, several groups worldwide involved in processing the satellite altimetry data regularly provide updates of sea level time series at global and regional scales. Here we present an ongoing effort supported by the Europea...
Article
Full-text available
The Copernicus Marine Environment Monitoring Service (CMEMS) Ocean State Report (OSR) provides an annual report of the state of the global ocean and European regional seas for policy and decision-makers with the additional aim of increasing general public awareness about the status of, and changes in, the marine environment. The CMEMS OSR draws on...
Conference Paper
Full-text available
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...
Presentation
Full-text available
The better observation of mesoscale and sub-mesoscale oceanic structures is a major challenge of altimetry community in the future years. Indeed, to date, the sea level content provided by most of the conventional altimeters does not allow the observation of ocean scales smaller than 80-100km. (Dibarboure et al., 2014) has shown that this limitatio...
Article
Full-text available
The new DUACS DT2014 reprocessed products have been available since April 2014. Numerous innovative changes have been introduced at each step of an extensively revised data processing protocol. The use of a new 20-year altimeter reference period in place of the previous 7-year reference significantly changes the sea level anomaly (SLA) patterns and...
Article
Full-text available
The new dynamic atmospheric correction (DAC) and dry tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed for the 1992-2013 altimeter period. Using these new corrections significantly improves sea level estimations for short temporal signals (<ĝ€2 months); the impact is stronger if considering old a...
Article
Full-text available
Mean sea level (MSL) is a prominent indicator of climatic change (Ablain et al., 2015; Cazenave et al., 2014; Leuliette and Willis, 2011), and is therefore of great scientific and societal interest. Since the beginning of the altimeter mission TOPEX/Poseidon, followed by Jason-1 and Jason-2 on similar orbits, and many other missions on different or...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
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...
Article
Full-text available
This study presents the evaluation of the performances of satellite altimeter missions by comparing the altimeter sea surface heights with in-situ dynamic heights derived from vertical temperature and salinity profiles measured by Argo floats. This external assessment method contributes to altimeter Calibration and Validation analyses that cover a...
Article
Full-text available
The new DUACS DT2014 reprocessed products are available since April 2014. Numerous and impacting evolutions have been implemented at each step of this new data processing. The main one is the use of a new 20-year altimeter reference period that changes the SLA and SLA gradient signature. Although all the DUACS products have been improved, this pape...
Article
Full-text available
New Dynamic Atmospheric Correction (DAC) and Dry Tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed on the 1992-2013 altimeter period. Using these new corrections improves significantly sea-level estimations for short temporal signals (< 2 months); the impact is stronger if considering old altimet...
Article
Full-text available
The Copernicus Marine Environment Monitoring Service (CMEMS) Ocean State Report (OSR) provides an annual report of the state of the global ocean and European regional seas for policy and decision-makers with the additional aim of increasing general public awareness about the status of, and changes in, the marine environment. The CMEMS OSR draws on...
Article
Full-text available
Based on the sea level budget closure approach, this study investigates the residuals between observed global mean sea level (GMSL) and the sum of components (steric sea level and ocean mass) for the period January 2005 to December 2013. The objective is to identify the impact of errors in one or several components of the sea level budget on the re...
Article
Full-text available
The wet tropospheric correction (WTC) is still a significant error source in most altimetric products. For studies such as sea level change, as those performed in the scope of the ESA Sea Level Climate Change Initiative (SL_cci) project, the use of uniform and consistent WTC datasets are of major importance. For this purpose, a set of improved WTC,...
Article
Full-text available
The current mean sea level (MSL) continuous record, essential for the understanding of climate evolution, is computed with the altimetric measurements of the TOPEX/Poseidon mission, succeeded by Jason-1 and later Jason-2. The accurate continuity of the record is ensured by the conservation of the "historical" TOPEX orbit, but also by calibration ph...
Article
Full-text available
Based on the sea level budget closure approach, this study investigates the residuals between observed global mean sea level (GMSL) and the sum of components (steric sea level and ocean mass) for the period January 2005 to December 2013. The objective is to identify the impact of errors in one or several components of the sea level budget on the re...
Article
Full-text available
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...