The original CryoSat-2 Payload Data Ground Segment (PDGS) was mostly based upon the CryoSat-1 design, built on technologies of the early 2000’s. Since the CryoSat-2 launch in April 2010 the CryoSat-2 PDGS has been subject of constant evolutions and improvements in the wake of keeping seamless and smooth operations. From the initial focus on Ice monitoring, the mission has extended its capability toward Ocean altimetry, introducing a new complete class of products which have caused more than doubling the number of the files produced. In parallel, use of commercial services has been introduced in specific domains where services maturity was allowing that, such as data dissemination and data preservation. Also use of advanced technologies has been gradually introduced where possible (e.g. dismissal of tape archives in favor of disk arrays and use of virtualised platforms). The current CryoSat-2 PDGS is therefore the result of a constant evolution which shall be illustrated in the presentation, posing focus on some specific areas.

Although the number of servers has doubled and their performance is much higher, Data Processing is still done through an array of dedicated high performance servers. Due to the nature of the mission which is systematic and to the resulting constant processing load, it has been decided to keep the concept of physical servers rather than moving toward the use of virtualised platforms. Usage of the CPU is constantly monitored and processing load is assigned to available resources.

Data dissemination is today done via a managed hosting service, where virtual machines with wide storage space and connected to the Service Provider’s backbone, are allocated to the entire CryoSat data publication function. Together with the traditional ftp dissemination, users have been recently given the possibility to access data via http/https.

Performance measurement is now achieved through a dedicated system which provides a detailed analysis of the production as well as a dashboard for the constant appreciation of the PDGS key performance as processing time, dissemination delay and production completeness. The same system is used for automated statistics and reporting.

A special emphasis has been placed on CryoSat Mission data preservation and protection. A very specific process has been consolidated in order to ensure that any usable data downloaded from the SIRAL instrument is converted in a product. Data completeness is constantly monitored and any possible data unavailability is justified and announced to users. As data are generated and sent to the users, they are also encapsulated in specific EO-SIP packages and sent to the Preservation Element based on a combination of a commercial service (DAS) and an internal storage function which are shared among the several ESA Earth Explorers and Third Party Missions.

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Going beyond its original ice-monitoring mission objective, CryoSat is now a valuable source of data for the oceanographic community. CryoSat’s radar altimeter can measure high-resolution geophysical parameters from the open ocean to the coast. To enable their full scientific and operational exploitation, the CryoSat ocean products are continuously evolving, through updates and improvements to the associated CryoSat Ocean Processors.

Since November 2017, the CryoSat ocean products are generated with Baseline-C, which represented a major processor upgrade. Several improvements were implemented in this new Baseline, most notably the generation of ocean products for all data acquisition modes (LRM, SAR and SARIn), therefore providing complete data coverage for ocean users. This upgrade also implemented innovative algorithms, refined some existing algorithms and added a number of new parameters and corrections to the products. Additionally, to maximise the uptake and use of CryoSat data by scientific users, the ocean product format was migrated from Earth Explorer Format to NetCDF format. These changes are expected to further improve the quality of the CryoSat ocean products and further promote their application to a broad range of oceanographic and climate studies.

The CryoSat ocean products are routinely monitored as part of Quality Control (QC) activities by the ESA/ESRIN Sensor Performance, Products and Algorithms (SPPA) office with the support of the Instrument Data quality Evaluation and Analysis Service (IDEAS+) led by Telespazio VEGA UK. IDEAS+ are also closely involved in CryoSat Ocean Processor validation activities prior to the installation of a new processor at the Payload Data Ground Segment. Activities involve the verification of test data generated with the new processor and validation that all expected changes have been made and no additional data quality anomalies have been introduced.

This poster provides an overview of the CryoSat ocean data quality status, in particular covering the validation and verification of the latest Baseline-C Ocean Processors, performed by IDEAS+. Also presented are known processor anomalies relating to the current Baseline-C, which are expected to be resolved in the next update to the CryoSat Ocean Processors.

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Launched in 2010, the European Space Agency’s (ESA) polar-orbiting CryoSat satellite was specifically designed to measure changes in the thickness of polar sea ice and the elevation of the ice sheets and mountain glaciers. To reach this goal, the CryoSat products have to meet the highest performance standards, achieved through continual improvements of the associated Instrument Processing Facilities.

Since April 2015, the CryoSat ice products are generated with Baseline-C, which represented a major processor upgrade and implemented several improvements, most notably the inclusion of freeboard data within the Level 2 SAR products. The Baseline-C upgrade has brought significant improvements to the quality of Level 1B and Level 2 products relative to the previous Baseline-B products, which in turn is expected to have a positive impact on the scientific exploitation of CryoSat measurements over land ice and sea ice. The CryoSat Baseline-C ice products are routinely monitored as part of Quality Control (QC) activities by the ESA/ESRIN Sensor Performance, Products and Algorithms (SPPA) office with the support of the Instrument Data quality Evaluation and Analysis Service (IDEAS+).

Based on the feedback and recommendations from Quality Control activities, Calibration and Validation campaigns, the CryoSat Expert Support Laboratory (ESL), and the Scientific Community, there are already several planned evolutions for the next ice processor Baseline. These include processor improvements for Antarctic and Arctic sea ice, implementation and optimisation of freeboard computation in SARIn mode, tuning of the land ice retracker, the switch to netCDF and the resolution of data quality anomalies present in the Baseline-C products.

This poster provides an overview of the CryoSat ice data quality assessment, covering all quality control activities performed by the Telespazio VEGA UK led IDEAS+ consortium, as well as the status of known processor anomalies relating to the current Baseline-C. Also discussed are the forthcoming evolutions and improvements anticipated in the next upgrade to the ice processors in order to further improve data characteristics, assessment and exploitation over Polar Regions.

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The ESA (European Space Agency) mission Cryosat-2, launched in 2010, differs from other altimetry missions (Jason-class missions, Envisat, AltiKa, …) as it has been designed to monitor the fluctuations of the thickness of land and marine ice fields (Wingham et al., 2006). To enhance the measurement resolution and precision over these surfaces, the on board altimeter SIRAL is based on a different principle proposed by Raney (1998): the Synthetic Aperture Radar mode (SARM) also referred to as Delay Doppler Mode. Although the Cryosat-2 mission is dedicated to the cryosphere observation and was initially designed for this purpose, the altimeter also provides measurements over ocean.

Most of the time the SIRAL altimeter acquires ocean observations in LRM mode while only a few oceanic regions are acquired in SAR and SARiN modes. The ESA Cryosat-2 Ocean Processing (COP) chain was initially developed to provide LRM and P-LRM products over oceans. Labroue et al. in 2012 and Calafat et al. in 2017 performed the assessment of these datasets and showed that the data quality and the level of accuracy are equivalent to that obtained for other currently operational altimeters. Recent evolutions brought to the COP baseline-C aims at improving the quality of these products by introducing SARM and SARiN mode processing.

The objective of this document is thus to assess and give feedbacks about the quality of these Cryosat-2 new products derived from the COP baseline C. Cross comparison with other altimeters will be performed to describe the performances and residual errors bring by the SARM processing.

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ESA's Earth Explorer CryoSat mission is dedicated to precise measurement of the changes in the thickness of marine ice floating on the polar oceans and variations in the thickness of the vast ice sheets that overlie Greenland and Antarctica. With the effects of a fast-changing climate becoming apparent, particularly in the Polar Regions, it is increasingly important to understand exactly how Earth's ice fields are responding. Diminishing ice cover is frequently cited as an early casualty of global warming and since ice plays an important role regulating climate and sea level, the consequences of change are far-reaching.
To understand fully how climate change is affecting these remote but sensitive regions, there remains an urgent need to determine exactly how the thickness of the ice, both on land and floating in the sea, is changing. By addressing this challenge, the data delivered by the CryoSat mission is completing the picture and lead to a better understanding of the ice role in the Earth system. To achieve this, the quality of the orbit and altimeter data have to meet the highest performance possible, not only over the ice caps and sea-ice surface but also over the oceans.

We present the results of our work to validate CryoSat's Precise Orbit (POE) generated by CNES and Geophysical Ocean product (GOP) generated by ESA's CryoSat Ocean Processor (COP). It consists of the computation of precise orbit solutions and comparison with the Cryosat mission precise orbit products, of the advancement of orbit determination techniques and models, and of the long-term monitoring, validation, and cross-calibration of the CryoSat Level-2 GOP data with the support of external measurements, numerical models, and the RADS system. Objectives are to assess the long-term quality and stability of CryoSat's measurement system for oceanographic applications at climate and inter-annual scales, and the identification and explanation of biases and drifts.

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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 the CryoSat mission (a refurbished ESA transponder developed for the ERS-1 altimeter calibration). It is located at the KSAT Svalbard station: SvalSAT. The transponder is used to calibrate SIRAL’s range, datation, and interferometric phase (or angle of arrival) to meet the mission requirements. Another transponder, deployed in 2015 in Crete for the Sentinel 3 calibration, has been included in the analysis.

In these calibrations, 3 different types of data have been used: the raw Full Bit Rate data, the stack beams before they are multi-looked (stack data) in the Level 1b processor, and the Level 1b data itself.

Ideally, the comparison between the theoretical values provided by the well-known target, and the measurement by the instrument to be calibrated provides us with the error that the instrument is introducing when performing its measurement. When this error can be assumed to be constant regardless of the conditions, it will provide the bias of the instrument.

If the measurements can be repeated after a certain period of time, it can also provide an indication of the instrument drift. This paper presents the range, datation and angle-of-arrival errors from the transponder data of eight years of data (from Baseline A to Baseline D) to derive potential biases and drifts.

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With the ability to operate in different modes, CryoSat-2 can provide a wealth of information not just over ice but over ice infested waters, the open oceans and coastal regions. After 9 years in orbit, CryoSat-2, ESA’s cryospheric mission, provides a variety of oceanographic products for the global oceans. A dedicated operational CryoSat-2 ocean processor (COP) has existed since April 2014 providing data in near real time (FDM/NOP), within ~3 days (IOP) and a geophysical ocean product (GOP) available within a month. In addition, the same processing chain has been used to provide data for longer scale studies (from November 2010 to November 2017). An improved processor version was introduced In November 2017.

In this presentation, we consider the quality and utility of the CryoSat-2 data in the open oceans where the altimeter operates mainly in conventional low-resolution-mode (LRM) but also in SARM (synthetic aperture radar mode) over a few regions.

Within the ESA funded CryOcean-QCV project, the UK's National Oceanography Centre (NOC) is responsible for routine quality control and validation of CryoSat Ocean Products. Activities include daily and monthly reports providing global assessments and quality control of Sea Surface Height Anomaly (SSHA), Significant Wave Height (SWH), backscatter coefficient (Sigma0) and wind speed, as well as a suite of validation protocols involving in situ data, model output and data from other satellite altimetry missions. This presentation will present some of the metrics and results obtained for CryoSat Ocean Products for SSHA, SWH and wind speed using data from tide gauges, wind and wave buoys, WaveWatch III wave model output, HF radar surface current data and comparisons with Jason-2 and Jason-3. Example metrics include SSHA along-track power spectra and the characterisation of offsets and variability regionally and in different sea states.

Finally, the utility of the data from CryoSat-2 for oceanographic studies will be demonstrated using sea surface height anomalies. We will present examples of the benefits for oceanographic studies using a Level 3 product, including investigations of propagating features (e.g. Rossby-type wave propagation).

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