DeDop: The tool to process altimetry data yourself

Mònica Roca i Aparici et al. (isardSAT, United Kingdom)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and retracking (SAR and LRM)

Presentation type: Type Poster

The recent development of SAR altimetry, or more properly Delay Doppler altimetry, as implemented on CryoSat-2 and now recently on Sentinel-3, opens an exciting new era for the scientific community. This new approach offers to scientists an opportunity to develop new processing schemes and derive new and improved products, and so maximise the benefits of the measurements available from upcoming missions.

Historically, in conventional altimetry, the understanding of the Level 1B processor was in the hands of the instrument engineers with system expertise.
Due to the strong link between the Level 1B processing and the final geophysical retrievals through the retracking process, it is important that the SAR Altimetry scientific community gains a much better understanding the Level 1B processor, and is involved in new developments. And this is the focus of the ESA DeDop project.

The DeDop project provides the scientific community with the means to understand and use low level Altimetry data and how these data are processed, by providing them with a Fully Adaptable and Configurable DDP and a friendly user interface (The DeDop “Studio”) to help them to interact with the DDP. The proposed DDP has different options from which the user will be able to choose according to their particular field of interest. Examples of the new options are: surface focusing (particularly relevant for special targets like coasts, rivers or lakes), any kind of weighting along and across track, different azimuth processing approaches, stack masking, new stacking algorithms (e.g. ACDC), Sigma-0 at stack level, etc.

The DDP is open source and the code will be freely available, in such a way that users will be able to explore the code and its configurable possibilities and to modify it to their own needs. The key algorithms for the DDP were developed within the ESA Sentinel-6 project.

When fully developed, the DeDop studio will also include various demonstrations of new features that can be investigated and retrieved; implemented as case-studies:

1. Iceberg Detection: Detection of target emerging from the sea surface. Examples of this are: icebergs, ships, lighthouse, and small islands.
2. Ocean Wind / Wave Modelling: Exploitation of the high-resolution altimetry for ocean wind-wave modelling.
3. Sea Ice: To improve discrimination of sea-ice through the use of stack data.
4. Inland Water: Evaluate use of DDP lL1B-S and L2 products for monitoring rivers and inland waters, focussing on the Amazon basin.
5. Transponder: The calibration of the main scientific parameters of the altimeter: range, datation, and Sigma-0.
6. Attitude Estimation: Demonstrate the retrieval of pitch of the Sentinel satellite, independent of the star trackers.
7. ACDC (Stack L1B waveform modelling): ACDC is a new method of forming the Doppler delay map, named Amplitude Compensation and Dilation Compensation. The objective of this study is to evaluate the stability of the ACDC.
8. Polar Ocean Eddies: To improve the estimation of the SSH across mesoscale eddies, in the sub-polar Arctic along the West Spitsbergen Current.
9. 3D Stack Modelling: Perform 3D fitting, or fit of the overall stack to test and quantify if precision and accuracy of geophysical retrievals is improved.

The DeDop Studio will be used to create and manage named DeDop Processor configurations, invoke the DeDop core processor with a given configuration and finally to read in the processor outputs for exploration and comparison with former outputs. It will have a clear, comprehensive, intuitive and accessible graphical user interface and comprise a flexible and extendible set of data visualisations and analysis functions for the L1A, L1BS and L1B outputs. As stated before, the ultimate aim of the DeDop Studio is to attract community scientists to use and modify the processing code and let them become acquainted with the new Level-1 altimeter products.

We will present and demonstrate the capabilities of the current version of the DeDop Processor and Studio, and present early outcomes of the various case studies.
 

Poster show times:

RoomStart DateEnd Date
Grande Halle Thu, Nov 03 2016,11:00 Thu, Nov 03 2016,18:00
Mònica Roca i Aparici et al.
isardSAT
United Kingdom
Monica.Roca@isardSAT.co.uk