A new phase in the production of quality-controlled sea level data

Abstract. 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 climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project merges data from 9 different altimeter missions in a clear and well-documented manner, selecting the most appropriate satellite orbits and geophyiscal corrections in order to reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset (DOI:10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. However, the overall result of these changes is that the rate of rise of global mean sea level still equates to ~3.2 mm yr−1 during 1992-2015.

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A new phase in the production of quality-controlled sea level data

Earth System Science Data ◽

10.5194/essd-9-557-2017 ◽

2017 ◽

Vol 9 (2) ◽

pp. 557-572 ◽

Cited By ~ 33

Author(s):

Graham D. Quartly ◽

Jean-François Legeais ◽

Michaël Ablain ◽

Lionel Zawadzki ◽

M. Joana Fernandes ◽

...

Keyword(s):

Sea Level ◽

Ocean Circulation ◽

Climate Models ◽

European Space Agency ◽

Rate Of Change ◽

Satellite Orbits ◽

Second Phase ◽

Regional Patterns ◽

Internal Climate Variability ◽

Space Agency

Abstract. 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 climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high-accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project (SL_cci) merges data from nine different altimeter missions in a clear, consistent and well-documented manner, selecting the most appropriate satellite orbits and geophysical corrections in order to further reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. The overall result of these changes is that the rate of rise of global mean sea level (GMSL) still equates to ∼ 3.2 mm yr−1 during 1992–2015, but there is now greater confidence in this result as the errors associated with several of the corrections have been reduced. Compared with v1.1 of the SL_cci dataset, the new rate of change is 0.2 mm yr−1 less during 1993 to 2001 and 0.2 mm yr−1 higher during 2002 to 2014. Application of new correction models brought a reduction of altimeter crossover variances for most corrections.

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An improved and homogeneous altimeter sea level record from the ESA Climate Change Initiative

Earth System Science Data ◽

10.5194/essd-10-281-2018 ◽

2018 ◽

Vol 10 (1) ◽

pp. 281-301 ◽

Cited By ~ 67

Author(s):

Jean-François Legeais ◽

Michaël Ablain ◽

Lionel Zawadzki ◽

Hao Zuo ◽

Johnny A. Johannessen ◽

...

Keyword(s):

Climate Change ◽

Sea Level ◽

Global Climate ◽

European Space Agency ◽

Bias Reduction ◽

Second Phase ◽

Change Initiative ◽

Internal Validation ◽

Spatial And Temporal Scales ◽

Space Agency

Abstract. 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 different altimetry missions that have provided global and regional observations of sea level variations. As part of the Climate Change Initiative (CCI) program of the European Space Agency (ESA) (established in 2010), the Sea Level project (SL_cci) aimed to provide an accurate and homogeneous long-term satellite-based sea level record. At the end of the first phase of the project (2010–2013), an initial version (v1.1) of the sea level ECV was made available to users (Ablain et al., 2015). During the second phase of the project (2014–2017), improved altimeter standards were selected to produce new sea level products (called SL_cci v2.0) based on nine altimeter missions for the period 1993–2015 (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612; Legeais and the ESA SL_cci team, 2016c). Corresponding orbit solutions, geophysical corrections and altimeter standards used in this v2.0 dataset are described in detail in Quartly et al. (2017). The present paper focuses on the description of the SL_cci v2.0 ECV and associated uncertainty and discusses how it has been validated. Various approaches have been used for the quality assessment such as internal validation, comparisons with sea level records from other groups and with in situ measurements, sea level budget closure analyses and comparisons with model outputs. Compared with the previous version of the sea level ECV, we show that use of improved geophysical corrections, careful bias reduction between missions and inclusion of new altimeter missions lead to improved sea level products with reduced uncertainties on different spatial and temporal scales. However, there is still room for improvement since the uncertainties remain larger than the GCOS requirements (GCOS, 2011). Perspectives on subsequent evolution are also discussed.

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An Accurate and Homogeneous Altimeter Sea Level Record from the ESA Climate Change Initiative

10.5194/essd-2017-116 ◽

2017 ◽

Cited By ~ 8

Author(s):

Jean-Francois Legeais ◽

Michaël Ablain ◽

Lionel Zawadzki ◽

Hao Zuo ◽

Johnny A. Johannessen ◽

...

Keyword(s):

Climate Change ◽

Sea Level ◽

Global Climate ◽

European Space Agency ◽

Bias Reduction ◽

Second Phase ◽

Change Initiative ◽

Internal Validation ◽

Spatial And Temporal Scales ◽

Space Agency

Abstract. 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 different altimetry missions that have provided global and regional observations of sea level variations. As part of the Climate Change Initiative (CCI) program of the European Space Agency (ESA) (established in 2010), the Sea Level project (SL_cci) aimed at providing an accurate and homogeneous long-term satellite-based sea level record. At the end of the first phase of the project (2010–2013), an initial version (v1.1) of the sea level ECV has been made available to users (Ablain et al., 2015). During the second phase (2014–2017), improved altimeter standards have been selected to produce new sea level products (called SL_cci v2.0) based on 9 altimeter missions for the period 1993–2015 (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). Corresponding orbit solutions, geophysical corrections and altimeter standards used in this v2.0 dataset are described in details in Quartly et al. (2017). The present paper focuses on the description of the SL_cci v2.0 ECV and associated uncertainty and discusses how it has been validated. Various approaches have been used for the quality assessment such as internal validation, comparisons with sea level records from other groups and with in-situ measurements, sea level budget closure analyses and comparisons with model outputs. Compared to the previous version of the sea level ECV, we show that use of improved geophysical corrections, careful bias reduction between missions and inclusion of new altimeter missions lead to improved sea level products with reduced uncertainties at different spatial and temporal scales. However, there is still room for improvement since the uncertainties remain larger than the GCOS requirements. Perspectives for subsequent evolutions are also discussed.

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An alternative method to improve gravity field models by incorporating GOCE gradient data

Earth Sciences Research Journal ◽

10.15446/esrj.v22n3.64666 ◽

2018 ◽

Vol 22 (3) ◽

pp. 187-193 ◽

Cited By ~ 1

Author(s):

Xiaoyun Wan ◽

Jiangjun Ran

Keyword(s):

Gravity Field ◽

Ocean Circulation ◽

Field Model ◽

Direct Method ◽

European Space Agency ◽

Gravity Field Model ◽

Alternative Method ◽

Space Agency ◽

Gravitational Model ◽

Gravity Field Models

The aim of this paper is to present an alternative method that can be used to improve existing gravity field models via the application of gradient data from Gravity field and Ocean Circulation Explorer (GOCE). First, the proposed algorithm used to construct the observation equation is presented. Then methods for noise processing in both time and space domains aimed at reducing noises are introduced. As an example, the European Improved Gravity model of the Earth by New techniques (EIGEN5C) is modified with gradient observations over the whole lifetime of the GOCE, leading to a new gravity field model named as EGMGOCE (Earth Gravitational Model of GOCE). The results show that the cumulative geoid difference between EGMGOCE and EGM08 is reduced by 4 centimeters compared with that between EIGEN5C and Earth Gravitational Model 2008 (EGM08) up to 200 degrees. The large geoid differences between EGMGOCE and EIGEN5C mainly exist in Africa, South America, Antarctica and Himalaya, which indicates the contribution from GOCE. Compared to the newest GOCE gravity field model resolved by direct method from European Space Agency (ESA), the cumulative geoid difference is reduced by 7 centimeters up to 200 degrees.

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Towards worldwide height unification using ocean information

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-365-11-2015 ◽

2015 ◽

Vol 365 ◽

pp. 11-15

Author(s):

P. L. Woodworth ◽

C. W. Hughes

Keyword(s):

North America ◽

Sea Level ◽

Tide Gauge ◽

European Space Agency ◽

Mean Sea Level ◽

Space Agency ◽

Height System ◽

Ocean Models ◽

Height System Unification

Abstract. This paper describes how we are contributing to worldwide height system unification (WHSU) by using ocean models together with sea level (tide gauge and altimeter) information, geodetic (GPS and levelling) data, and new geoid models based on information from the GRACE and GOCE gravity missions, to understand how mean sea level (MSL) varies from place to place along the coast. For the last two centuries, MSL has been used to define datums for national levelling systems. However, there are many problems with this. One consequence of WHSU will be the substitution of conventional datums as a reference for heights with the use of geoid, as the only true "level" or datum. This work is within a number of GOCE-related activities funded by the European Space Agency. The study is focused on the coastlines of North America and Europe where the various datasets are most copious.

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An Action Plan Towards Fiducial Reference Measurements for Satellite Altimetry

Remote Sensing ◽

10.3390/rs11171993 ◽

2019 ◽

Vol 11 (17) ◽

pp. 1993 ◽

Cited By ~ 7

Author(s):

Mertikas ◽

Donlon ◽

Vuilleumier ◽

Cullen ◽

Féménias ◽

...

Keyword(s):

Sea Level ◽

Satellite Altimetry ◽

Action Plan ◽

European Space Agency ◽

Earth Observation ◽

Sea Level Changes ◽

Space Agency ◽

Historic Record ◽

To Come ◽

Reference Measurements

Satellite altimeters have been producing, as of 1992, an amazing and historic record of sea level changes. As Europe moves into full operational altimetry, it has become imperative that the quality of these monitoring signals with their uncertainties should be controlled, fully and properly descripted, but also traced and connected to undisputable standards and units. Excellent quality is the foundation of these operational services of Europe in altimetry. In line with the above, the strategy of the Fiducial Reference Measurements for Altimetry (FRM4ALT) has been introduced to address and to achieve reliable, long-term, consistent, and undisputable satellite altimetry products for Earth observation and for sea-level change monitoring. FRM4ALT has been introduced and implemented by the European Space Agency in an effort to reach a uniform and absolute standardization for calibrating satellite altimeters. This paper examines the problem and the need behind the FRM4ALT principle to achieve an objective Earth observation. Secondly, it describes the expected FRM products and services which are to come into being out of this new observational strategy. Thirdly, it outlines the technology and the services required for reaching this goal. And finally, it elaborates upon the necessary resources, skills, partnerships, and facilities for establishing FRM standardization for altimetry.

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Physical processes that impact the evolution of global mean sea level in ocean climate models

Ocean Modelling ◽

10.1016/j.ocemod.2012.04.003 ◽

2012 ◽

Vol 51 ◽

pp. 37-72 ◽

Cited By ~ 68

Author(s):

Stephen M. Griffies ◽

Richard J. Greatbatch

Keyword(s):

Sea Level ◽

Climate Models ◽

Physical Processes ◽

Mean Sea Level ◽

Ocean Climate ◽

Global Mean Sea Level ◽

Global Mean

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Global Trend of Glacier Melting or Growing and its Impact on Heavy Storms

SAMRIDDHI A Journal of Physical Sciences Engineering and Technology ◽

10.18090/samriddhi.v8i1.11411 ◽

2016 ◽

Vol 8 (01) ◽

pp. 43-55

Author(s):

Bharat Raj Singh ◽

Onkar Singh

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Human Life ◽

European Space Agency ◽

Ice Sheet ◽

Good News ◽

Laser Altimeter ◽

Space Agency ◽

Ipcc Report ◽

The Antarctic

Scientists calculate how much the ice sheet is growing or shrinking from the changes in surface height that are measured by the satellite altimeters. In locations where the amount of new snowfall accumulating on an ice sheet is not equal to the ice flow downward and outward to the ocean, the surface height changes and the ice-sheet mass grows or shrinks. But it might only take a few decades for Antarctica’s growth to reverse, according to Zwally. If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they’ve been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years and it is questionable whether there will be enough snowfall increase to offset these losses. The study analyzed changes in the surface height of the Antarctic ice sheet measured by radar altimeters on two European Space Agency European Remote Sensing (ERS) satellites, spanning from 1992 to 2001, and by the laser altimeter on NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) from 2003 to 2008. The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away. But, this is also bad news. If the 0.27 millimeters per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for. On other hand, globally every country is facing heavy storm, disastrous rain fall and variance in Climate Change, causing greater loss in production of food grain, disruption of smooth living and development and enhancement of hazardous deceases on account of Global Warming and Climatic Changes. This paper focuses on the current issues and its remedial efforts to be made essentially to curb these issues and save human life and beautiful creatures on the globe.

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Arctic Ocean Sea Level Record from the Complete Radar Altimetry Era: 1991–2018

Remote Sensing ◽

10.3390/rs11141672 ◽

2019 ◽

Vol 11 (14) ◽

pp. 1672 ◽

Cited By ~ 6

Author(s):

Stine Kildegaard Rose ◽

Ole Baltazar Andersen ◽

Marcello Passaro ◽

Carsten Ankjær Ludwigsen ◽

Christian Schwatke

Keyword(s):

Time Series ◽

Confidence Interval ◽

Arctic Ocean ◽

Sea Level ◽

European Space Agency ◽

The Arctic ◽

Altimeter Data ◽

Sea Level Anomaly ◽

Radar Altimetry ◽

Space Agency

In recent years, there has been a large focus on the Arctic due to the rapid changes of the region. Arctic sea level determination is challenging due to the seasonal to permanent sea-ice cover, lack of regional coverage of satellites, satellite instruments ability to measure ice, insufficient geophysical models, residual orbit errors, challenging retracking of satellite altimeter data. We present the European Space Agency (ESA) Climate Change Initiative (CCI) Technical University of Denmark (DTU)/Technischen Universität München (TUM) sea level anomaly (SLA) record based on radar satellite altimetry data in the Arctic Ocean from the European Remote Sensing satellite number 1 (ERS-1) (1991) to CryoSat-2 (2018). We use updated geophysical corrections and a combination of altimeter data: Reprocessing of Altimeter Product for ERS (REAPER) (ERS-1), ALES+ retracker (ERS-2, Envisat), combination of Radar Altimetry Database System (RADS) and DTUs in-house retracker LARS (CryoSat-2). Furthermore, this study focuses on the transition between conventional and Synthetic Aperture Radar (SAR) altimeter data to make a smooth time series regarding the measurement method. We find a sea level rise of 1.54 mm/year from September 1991 to September 2018 with a 95% confidence interval from 1.16 to 1.81 mm/year. ERS-1 data is troublesome and when ignoring this satellite the SLA trend becomes 2.22 mm/year with a 95% confidence interval within 1.67–2.54 mm/year. Evaluating the SLA trends in 5 year intervals show a clear steepening of the SLA trend around 2004. The sea level anomaly record is validated against tide gauges and show good results. Additionally, the time series is split and evaluated in space and time.

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Analisa Sea Level Rise Dari Data Satelit Altimetri Topex/Poseidon, Jason-1 Dan Jason-2 Di Perairan Laut Pulau Jawa Periode 2000 – 2010

INDONESIAN JOURNAL OF APPLIED PHYSICS ◽

10.13057/ijap.v2i02.1296 ◽

2016 ◽

Vol 2 (02) ◽

pp. 65

Author(s):

Hastho Wuriatmo ◽

Sorja Koesuma ◽

Mohtar Yunianto

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Satellite Altimetry ◽

Sea Water ◽

Tide Gauge ◽

European Space Agency ◽

South Coast ◽

Altimetry Data ◽

Space Agency ◽

Satellite Altimetry Data

It has been conducted a research about sea level rise (SLR) in surrounding Jawa island by using satellite altimetry data Topex/Poseidon, Jason-1 dan Jason-2 for period 2000 – 2010. Satellite altimetry is satellite which specially design for measuring dynamics of sea water. Those satellite lauched firstly in 1992 incorporation between National Aeronautics and Space Administration (NASA) dan European Space Agency (ESA). There are six locations for measuring SLR i.e. Jakarta, Semarang, Surabaya, Pangandaran, Jogjakarta dan Prigi. We chose locations based on alongtrack of satellite and near the big cities in Jawa island with dimension area around 0.5ox0.5o degrees. We found SLR rate for Jakarta (2.5 ± 0.24 mm/yr), Semarang (2.16 ± 0.20 mm/yr), Surabaya (2.72 ± 0.19 mm/yr), Pangandaran (0.71 ± 0.33 mm/yr), Jogjakarta (0.91 ± 0.38 mm/yr) and Prigi (1.3 ± 0.38 mm/yr). The average SLR rate for North coast is (2.46 ± 0.21 mm/yr) and for South coast (0.97 ± 0.36 mm/yr). This results are well correlated with data from tide gauge stations.

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