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A global network of permanent sites for calibrating satellite altimetry missions

Final Report Summary - CALT (A global network of permanent sites for calibrating satellite altimetry missions)

This “CALT” project has been aimed at strengthening research partnerships between well-established European satellite altimetry calibration facilities and Chinese, as well as Brazilian organizations that operate new altimetric missions and/or calibration facilities. This partnership has resulted in the development of an international network for satellite altimetry calibration and will encompass the new altimetry stakeholders of Brazil and China. And this has constituted the primary objective of the “CALT” project.

A close collaboration with all existing global satellite altimeter calibration facility operators has been established for more than 10 years. Thus, in this “CALT” consortium, an effort has been made to include the other two international satellite altimeter calibration facilities located in Australia and the USA.

With this project consortium, new knowledge was shared and exchanged among all participants (Partners and external observers) for the benefit of the satellite altimetry community (objective two). The project focused on training activities, mutual exchange of knowledge, and skills through the establishment of a global scientific network between existing and future permanent dedicated satellite altimeter calibration sites (European and international). The aim was to confront current and future challenges, and establish best practices in satellite altimetry calibration on a common and internationally-adopted basis. Additionally, it aimed at sharing strengths and circumventing weaknesses within calibration methodologies and procedures applied at the various globally-distributed Cal/Val sites.

During the initial period of the research staff exchange for the “CALT” Project, it has been realized and testified that this current EU support had not been sufficient to maintain these research staff exchanges in this CALT Project. This project could not be implemented with the present EU support for the planned research staff exchanges, particularly, to third countries like China and Brazil. This fact has already been reported to the EU, and for that reason termination of the MELINA Project was requested on August 2014.

Work-performed and Main Results
The following research staff secondments and scientific achievements have been performed during the period October 2012–July 2014:

• FIO/SOA, China @ TUC, Greece. This exchange took place in December 2012. The technical specifications of the HY-2 altimetric mission (operating parameters, products format, models used, etc.) have been examined, and reviewed in detail. Moreover, utilization of the CRS1 site, operated by TUC, for the HY-2 satellite calibration in West Crete, Greece has been introduced and preliminary results have been evaluated.
• TUC, Greece @ FIO/SOA, China. This research staff exchange took place in March-April 2013, and its main purpose has been mainly the exchange of know-how regarding the microwave transponder for satellite calibration and the sea-surface satellite calibration methodology.
• TUC, Greece & CNRS/OCA, France @ UEA, Brazil. This joint exchange took place in October 2013. The main purpose of this collaboration has been to establish a satellite calibration facility for inland waters at the Amazon River, Manaus, Brazil.
• UEA, Brazil @ CNRS/OCA, France. This joint research staff exchange took place in March-April 2014. The main purpose of this has been to report from the advance in the work performed on SARAL/AltiKa satellite altimeter and to learn about dedicated retracking algorithm of satellite return signals for inland waters, such as the Amazon River.
• FIO/SOA, China @ TUC, Greece. This joint exchange took place in February-March 2014 and its main purpose was to evaluate candidate Calibration/Validation sites for the calibration of the Chinese HY-2 satellite missions in Crete, Greece and in China.

Publications:
Researchers from the “CALT” consortium presented, jointly, their work in the following conferences and workshops:

• Bonnefond, P., Laurain, O., Exertier, P., Guillot, A., Picot, N., Guinle, T., Femenias, P., “Corsica: a Cal/Val experiment to link offshore and coastal altimetry”, 8th Coastal Altimetry Workshop, Lake Constance, 23-24 October 2014.
• Mertikas, S., A. Daskalakis, I. Tziavos, G Vergos, H. Peng, X. Zhou, F. Qiao, (2014), “Latest absolute calibration results for Jason-2 and HY-2 satellites using the Gavdos/Crete permanent calibration facilities”, Ocean Surface Topography Science Team (OSTST) Conference, Lake Constance, Germany, 28-31 October, 2014.
• Haines B., P. Bonnefond, S. Mertikas, K.N. Babu, (2014), “Absolute calibration of the SARAL/AltiKa measurement system at Corsica and Harvest”, SARAL/AltiKa workshop, Lake Constance, Germany, 27 October, 2014.
• Santos da Silva, J., S. Calmant, D. Moreira, M-C Gennero, M-P Bonnet, F. Seyler, F. Frappart, T. Conchy, R. Oliveira, L. Bacharach, (2014), “Validation of SARAL/AltiKa data in the Amazon basin”, SARAL/AltiKa workshop, Lake Constance, Germany, 27 October, 2014.
• Watson C., B. Haines, P. Bonnefond, (2014), “Long term absolute calibration from Bass Strait, Harvest and Corsica sites”, Ocean Surface Topography Science Team (OSTST) Conference, Lake Constance, Germany, 28-31 October, 2014.
• Cancet M., C. Watson, B. Haines, P. Bonnefond, E. Jeansou, F. Lyar, P. Femenias, (2014), “Regional Cal/Val of Jason-2 and Envisat at three calibration sites: Corsica, harvest and Bass Strait”, Ocean Surface Topography Science Team (OSTST) Conference, Lake Constance, Germany, 28-31 October, 2014.

During the 2013 Ocean Surface Topography Science Team (OSTST) Conference, Boulder, Colorado, USA, 8-11 Oct, 2013, the following CALT presentations were given:
• P. Bonnefond, P. Exertier, O. Laurain, T. Guinle, P. Femenias; "Corsica: a multi-mission absolute calibration site",
• M. Cancet, B. Haines, P. Bonnefond, E. Jeansou, F. Lyard, P. Féménias, "Regional CalVal of Jason-2 and Envisat in Corsica and at Harvest".
• R. Morrow, P. Bonnefond, L-L Fu, J. Willis, T. Guinle, G. Shirtliffe, "Jason-1: three successful phases of ocean monitoring".
• S. Mertikas, A. Daskalakis, H. Peng, I. N. Tziavos, X. Zhou, G. Vergos, V. Zervakis, O. B. Andersen, "Latest Results for the absolute calibration of Jason and HY-2 satellites using the Gavdos/Crete permanent calibration facility".
• S. Mertikas, C. Mavrocordatos, N. Picot, P. Femenias, T. Parrinello, A. Daskalakis, "Preparatory steps for a permanent infrastructure in West Crete to calibrate Sentinel-3, Cryosat-2 and Jason missions with a prototype microwave transponder".
• D. Blumstein, F. Niño, S. Fleury, N. Steunou, F. Boy, F. Remy, S. Calmant, F. Birol, "Inversion of Saral/AltiKa waveforms over different surfaces".

In addition, at the 7th Coastal Altimetry Workshop, Boulder, Colorado, USA, Oct, 2013, the following presentations were given by CALT Partners:
• P. Bonnefond, P. Exertier, O. Laurain, A. Guillot, T. Guinle, N. Picot,P. Féménias, "Corsica: a Cal/Val experiment to link offshore and coastal altimetry".
• S. Mertikas, A. Daskalakis, I. N. Tziavos, G. Vergos, V. Zervakis, "Analysis of Sea Level Trends with Altimetry Around the Coastal Zone of Gavdos Permanent Cal/Val Facility".

As well as several other presentations at the International SARAL/AltiKa Science & Applications Meeting, Indian Space Research Organization, Ahmedabad, India, April, 2014.

Also,elsewhere:
• P. Bonnefond, P. Exertier, O. Laurain, A. Guillot, T. Guinle, N. Piccot. “Absolute Calibration of SARAL/AltiKa in Corsica”. Special SARAL/AltiKa Issue, AVISO Users Newsletter, 10-Dec-2013 (Editors-in-Chief: C. Maheu).
• S. Calmant, J.S. da Silva, D. M. Moreira, F. Seyler. “SARAL/AltiKa: Altimetry over rivers”. Special SARAL/AltiKa Issue, AVISO Users Newsletter, 10-Dec-2013, (Editors-in-Chief: C. Maheu).

Finally, the following papers have also been submitted, by CALT members, to the Marine Geodesy Journal, Special Issue on SARAL/AltiKa satellite (To appear in April 2015):
• Bonnefond, P., Laurain, O., Exertier, P. Guillot, A. Picot, N.; Cancet, M., Lyard F.:: SARAL/AltiKa absolute calibration from the multi-mission Corsica facilities, Submitted to Marine Geodesy.
• Babu K. N., Shukla, A. K., Arun, S. V. V., Bonnefond, P., Testut, L.: “Altimeter calibration experiment at Kavaratti site using GPS buoy, tide gauge”, Submitted to Marine Geodesy.
• Babu K. N., Shukla, A. K., Suchandra, A. B., Arun, S. V. V., Bonnefond, P., Testut, L., and Mehra, P.: “Absolute calibration of SARAL-AltiKa in Kavaratti during its initial calibration-validation phase” , Submitted to Marine Geodesy.
• Mertikas, S.P. A. Daskalakis, I.N. Tziavos, G. Vergos, V. Zervakis: First results for the calibration values of SARAL/AltiKa using the Gavdos permanent facilities, Submitted to Marine Geodesy.
• Santos da Silva J., D. Medeiros Moreira, S. Calmant, M. C., Gennero, F. Frappart, F. Papa, F. Seyler, T. Conchy, C. K. Shum: Validation of SARAL/AltiKa/ICE-1 measurements over the Amazon basin and determination of the absolute bias by comparison with levelled gauges series, Submitted to Marine Geodesy.
• Cretaux J-F., Calmant S, Bergé-Nguyen M, Romanevski V.V Tashbaeva S., et al.,: Absolute calibration of SARAL/Altika over the Lake Issykkul, Submitted to Marine Geodesy.
• Frappart F., F. Papa, F. Jordy, V. Marieu, Y. Malbeteau, S. Calmant and S. Bala: A first assessment of SARAL-AltiKa observations over the Ganges-Brahmaputra river basin: In situ validation and cross-calibration with ENVISAT and Jason-2, Submitted to Marine Geodesy.

Partnership and Contact Details:

• Geodesy & Geomatics Engineering Lab, Technical University of Crete, Greece. Prof. S.P. Mertikas. Telephone: +30 28210 37629, Email: mertikas@mred.tuc.gr;
• Centre National de la Recherche Scientifique. Observatoire de la Cote d’ Azur, France. Dr. P. Bonnefond, Telephone: +33 49 34 05 363, Email: Pascal.Bonnefond@obs-azur.fr;
• The First Institute of Oceanography, State Oceanic Administration, China. Prof. Zhou, Telephone: +86 532 8896 6632, Email: xhzhou@fio.org.cn;
• Universidade do Estado do Amazonas, Brazil. Dr. Joecila SANTOS DA SILVA, Telephone: +55
923 238 6569, Email: jsdsilva@uea.edu.br;

• CALT Project web-site: http://www.tuc.gr/3391.html