TUDaBO SAR-RDSAR – U.Bonn

PROVIDER

TU Darmstadt and U Bonn

TUDaBO SAR-RDSAR – U.Bonn

TUDaBO SAR-RDSAR – U.Bonn is a processor prototype developed by C. Buchhaupt and L. Fenoglio-Marc at TU Darmstadt and U Bonn to experiment with SAR mode data from L1A (FBR) to L2. Reduced SAR, unfocused SAR, and LRMC data can be generated for both CryoSat-2 and Sentinel-3A. For each mode, dedicated signal processing options and retrackers are available, which allow the user to experiment with different configurations. All L1B/L2 products for reduced SAR, unfocused SAR, and LRMC have the same geolocations and time tags, allowing a direct comparison without interpolation.

EarthConsole^® P-PRO TUDaBO SAR-RDSAR – U.Bonn Software Prototype User Manual

Introduction

The EarthConsole^®> P-PRO TUDaBo SAR-RDSAR (Technical University Darmstadt – University Bonn SAR-Reduced SAR) serviceis a web service that provides the capability to process on line and on demand SAR mode Full Bit Rate (FBR or L1A) data to Level-1B and Level-2 geophysical data products. The service is based on a SAR-RDSAR Processor Prototype that has been developed and tested by Christopher Buchhaupt and Luciana Fenoglio-Marc in TU Darmstadt and at the University of Bonn. Available modes to generate L1B and L2 data are reduced SAR, unfocused SAR and LRMC, whereas several signal processing options and retrackers are available. The output data products are in standard NetCDF format and follow in large part the format and variable names of RADS products.

List of option entries, output options and adopted conventions

List of option entries

The users can customize and adapt the processing, according to their specific requirements, setting a list of configurable options grouped according to the processing level (L1B and L2).

General Options

Mission	CryoSat-2	Satellite mission which L1A data is going to be processed.
	Sentinel-3A
Reference ellipsoid	WGS84	Reference ellipsoid used for the vertical datum.
	TOPEX
	GRS80

L1B Processing Options:

Option Name	Option Value	Option Description
Use RADS bias	No	Flag to determine if the RADS roll/pitch and range bias shall be used in the L1B processing. Alternatively the biases for roll/pitch and range are treated as in CryoSat-2 Baseline-C products. For Sentinel-3A no biases exists.
	Yes
Process RDSAR	Yes	Flag to determine if RDSAR L1B data shall be processed.
	No
Process unfocused SAR	Yes	Flag to determine if unfocused SAR L1B data shall be processed.
	No
Process LRMC	Yes	Flag to determine if LRMC L1B data shall be processed.
	No
Distribution of pulse/beam samples	Exponential	Stochastic distribution of the L1B data before the averaging, which is in state-of-the-art processing exponential. By selecting “Zero skewness Weibull” a transform is applied to achieve a sample power distribution close to normal.
	Zero skewness Weibull
Use Hamming window	No	Flag to determine if a Hamming window shall be applied before each FFT.
	Yes
Apply zero padding	Yes	Flag to determine if zero padding shall be applied before each FFT.
L1B sampling frequency	20 Hz	Sampling rate of L1B data. 20 Hz corresponds to a distance between samples of about 320 m, 40 Hz to about 160 m and 80 Hz to about 80 m.
	40 Hz
	80 Hz
Local surface approximation	Sphere	Surface representation used in the processing. “Sphere” assumes a globally constant curvature, “Ellipsoid” applies latitude dependent curvatures, “Slopes” includes geoid slopes and “Geoid” adds additionally the geoid curvatures.
	Ellipsoid
	Slopes
	Geoid

L2 Processing Options:

Option Name	Option Value	Option Description
Retracked surface	Water	Flag to determine the surface which is going to be retracked. “Water” are locations which are flagged by the MODIS water-land mask as water and “Ocean” are water locations with a distance to coast greater than 10km.
	Ocean
	All
	None
Retracker RDSAR	BMLE3	Retracker used to generate RDSAR L2 data. BMLE3 is a state-of-the-art conventional altimetry retracker based on the Brown-Hayne model. SINC2 is a fast convolution based adaption of BMLE3, which does not use a PTR approximation. TALES is SINC2 using an ALES approach to lessen land contamination effects on L1B data.
	SINC2
	TALES
	NONE
Retracker unfocused SAR	SINCS	Retracker used to generate unfocused SAR L2 data. SINCS is a fast convolution based SAR waveform retracker, which does not apply a PTR approximation. SINCS-OV is an adaption of SINCS including vertical wave orbital velocities by retracking the stack or L1B-S data.
	SINCS-OV
	NONE
Retracker LRMC	SINCS	Retracker used to generate LRMC L2 data. SINCS is a fast convolution based SAR waveform retracker, which does not apply a PTR approximation. SINCS-OV is an adaption of SINCS including vertical wave orbital velocities by retracking the stack data.
	SINCS-OV
	NONE

Output Options:

Option Name	Option Value	Option Name
Dump waveforms	Yes	Flag to determine if the waveforms (L1B) shall be stored in the NetCDF output file.
	No
Store Stack Data	Yes	Flag to determine if the stack data (L1B-S) shall be stored in the NetCDF output file.
	No

Adopted Conventions

The Reference Time for UTC is 01/01/1985 00:00:00
The Curve Best-Fitting Scheme, used in the retracking stage, is a Levenberg Marquardt Least-Squares Estimation Algorithm (LEVMAR-LSE).
Static bias has been applied to the range, sigma nought and antenna mispointing measurements. The values of the static biases are reported in the output NetCDF data products.
The orbital altitude has been corrected for a Time Tag Bias. The value of the applied time tag bias is reported in the output NetCDF data products.
The measurements are posted both at a rate of 20 Hz/40 Hz/80 Hz and of 1 Hz.
The sea state bias correction has not been applied to the sea level anomaly estimates.
All the default geophysical path corrections are from the FBR products.
No a priori data editing has been applied to the 20 Hz/40 Hz/80 Hz measurements.
The misfit between a waveform model and waveform data has been computed as:

where ???????? are the differences between model’s waveform power and data’s waveform power, normalized for the waveform power’s maximum value and ???? is the number of sampled considered during retracking.

Output Format

Acronyms and References

Acronyms

EOP-SER Earth Observation Programmes: Science, Exploitation, Research
FBR Full Bit Rate
GRS Geodetic Reference System
L1A Level 1A
L1B Level 1B
L1B-S Level 1B-S
L2 Level 2
LRMC Low resolution mode with range cell migration correction
RADS Radar Altimeter Database System
RDSAR Reduced SAR SAR Synthetic Aperture Radar
SINC Signal model involving numerical convolutions
SINC2 SINC based conventional altimetry retracker
SINCS SINC based SAR altimetry retracker
SINCS-OV Extension of SINCS introducing orbital wave velocities
WGS World Geodetic System

References

Buchhaupt C., Fenoglio-Marc L., Dinardo S., Scharroo R., Becker M (2018). A fast convolution based waveform modell for conventional and unfocused SAR altimetry, Advanced Space Research Special Issue CryoSat-2, https://doi.org/10.1016/j.asr.2017.11.039

Buchhaupt, C., (2019). Model Improvement for SAR Altimetry, PhD Thesis, University of Darmstadt, tuprints.ulb.tu-darmstadt.de/9015/

Fenoglio L. and Buchhaupt C. (2020). TUDaBo SAR-RDSAR for G-POD Altimetry Coastal and Open Ocean Performance -Algorithm Theoretical Basis Document (ATBD), ESA Reference number: EOEP-SEOM-EOPSTN-17-046, Version 1.6, 30-01-2020

How to request the service

To benefit from our services, we first invite you to register on the EarthConsole^® Webapp and thoroughly fill-in the P-PRO service request form. Note that in the service request form you are required to specify whether you want to request ESA sponsorship or not. Your selection will imply that you are choosing one of the following options:

Option 1 “Sponsorship Request via ESA NoR”

If you have a research, development or pre-commercial project, you may be eligible to submit a sponsoring request via the ESA NoR portal. If the sponsorship request will be approved, this would cover partially or totally the cost of the P-PRO service. To guide you through the sponsoring submission procedure, we have prepared this Step-by-Step Manual.

Once your sponsoring request will be approved by ESA, we will be able to activate your P-PRO service.

We encourage you to let us know in case you need administrative assistance at info@earthconsole.eu as we can help you fill-in the form. In any case, when you will submit your sponsoring request to ESA we recommend to keep support@earthconsole.eu, altimetry.info@esa.int, and info@earthconsole.eu in cc to speed-up the evaluation process.

If you are not eligible to apply for a sponsorship via the NoR portal or in case of rejection, option n° 2 is always available.

Option 2 “Unsponsored Service Activation”

Following the request of the desired service via the EarthConsole^® Webapp, we will send you a quotation of the service for your approval together with the instructions to proceed with the payment.
The prices available in this pricing list cover most of the typical users’ requests. 15% discount is applicable to research, development, pre-commercial and educational projects. Special discounts can be applied in the case of requests for subscription plans. Ad-hoc quotations are available on-demand.

Contact Us

For any question, bug-reports or support on the processor please contact the ESA Altimetry Team at: altimetry.info@esa.int. For EarthConsole^® P-PRO specific questions please contact: support@earthconsole.eu.

PROVIDER

TUDaBO SAR-RDSAR – U.Bonn

Resources

Headquarters