The SARAL/AltiKa Altimetry Satellite Mission

Verron, Jacques; Sengenes, P.; Lambin, J.; Noubel, J.; Steunou, N.; Guillot, Amandine; Picot, Nicolas; Coutin-Faye, Sophie; Sharma, Rashmi; Gairola, R. M.; Murthy, Durbha V.; Richman, James G.; Griffin, David A.; Pascual, Ananda; Rémy, Frédérique; Gupta, Praveen Kumar

doi:10.1080/01490419.2014.1000471

Cited by 145 publications

(93 citation statements)

References 4 publications

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“…This data set was chosen because the new Ka-band instrument from SARAL has a finer spatial resolution and enables a better observation of coastal zones (Verron et al, 2015). Data extend from March 2013 (cycle 1 of the satellite mission) to May 2016 (cycle 33), with a repeat period of 35 days.…”

Section: Methodsmentioning

confidence: 99%

Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall

Ampou

Johan²,

Menkès

et al. 2017

Biogeosciences

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Abstract. The 2015–2016 El-Niño and related ocean warming has generated significant coral bleaching and mortality worldwide. In Indonesia, the first signs of bleaching were reported in April 2016. However, this El Niño has impacted Indonesian coral reefs since 2015 through a different process than temperature-induced bleaching. In September 2015, altimetry data show that sea level was at its lowest in the past 12 years, affecting corals living in the bathymetric range exposed to unusual emersion. In March 2016, Bunaken Island (North Sulawesi) displayed up to 85 % mortality on reef flats dominated by Porites, Heliopora and Goniastrea corals with differential mortality rates by coral genus. Almost all reef flats showed evidence of mortality, representing 30 % of Bunaken reefs. For reef flat communities which were living at a depth close to the pre-El Niño mean low sea level, the fall induced substantial mortality likely by higher daily aerial exposure, at least during low tide periods. Altimetry data were used to map sea level fall throughout Indonesia, suggesting that similar mortality could be widespread for shallow reef flat communities, which accounts for a vast percent of the total extent of coral reefs in Indonesia. The altimetry historical records also suggest that such an event was not unique in the past two decades, therefore rapid sea level fall could be more important in the dynamics and resilience of Indonesian reef flat communities than previously thought. The clear link between mortality and sea level fall also calls for a refinement of the hierarchy of El Niño impacts and their consequences on coral reefs.

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Section: Methodsmentioning

confidence: 99%

Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall

Ampou

Johan²,

Menkès

et al. 2017

Biogeosciences

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“…Compared to previous altimeters that are using the Ku-band at 13.6 GHz (and 20-Hz posting rate), SARAL/AltiKa is expected to provide better vertical resolution of the range thanks to a larger bandwidth, and improved horizontal resolution thanks to a narrower antenna beam (footprint diameter is only 8 km compared to 20 km on Jason-2), at the cost of higher sensitivity to rain events (Vincent et al 2006;Steunou et al 2015). The high precision measurements provided by the altimeter are very valuable for the characterization of coastal sea level and dynamics, which is one of the main scientific objectives of the SARAL/AltiKa mission (Verron et al 2015). The current geophysical data record (GDR) products (GDR-T patch 2 version) are dedicated to open ocean, but the CNES PEACHI prototype processes high rate data with up-to-date algorithms for different surfaces (coastal, ice, hydrology).…”

Section: Ka-band Altimetry: Altikamentioning

confidence: 99%

Monitoring Sea Level in the Coastal Zone with Satellite Altimetry and Tide Gauges

et al. 2016

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We examine the issue of sustained measurements of sea level in the coastal zone, first by summarizing the long-term observations from tide gauges, then showing how those are now complemented by improved satellite altimetry products in the coastal ocean. We present some of the progresses in coastal altimetry, both from dedicated reprocessing of the radar waveforms and from the development of improved corrections for the atmospheric effects. This trend towards better altimetric data at the coast comes also from technological innovations such as Ka-band altimetry and SAR altimetry, and we discuss the advantages deriving from the AltiKa Ka-band altimeter and the SIRAL altimeter on CryoSat-2 that can be operated in SAR mode. A case study along the UK coast demonstrates the good agreement between coastal altimetry and tide gauge observations, with root mean square differences as low as 4 cm at many stations, allowing the characterization of the annual cycle of sea level along the UK coasts. Finally, we examine the evolution of the sea level trend from the open to the coastal ocean along the western coast of Africa, comparing standard and coastally improved products. Different products give different sea level trend profiles, so the recommendation is that additional efforts are needed to study sea level trends in the coastal zone from past and present satellite altimeters. Further improvements are expected from more refined processing and screening of data, but in particular from the constant improvements in the geophysical corrections.

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“…2.1.3. Absolute Calibration, Validation of SARAL/AltiKa over the Lake Issykkul SARAL/AltiKa is used over the continents to measure the water height changes of lakes and rivers [1]. In order to determine the performances of altimeters over inland waters, a dedicated site of calibration/validation has been setup in 2004 over the lake Issykkul.…”

Section: Saral/altika Absolute Calibration Over Corsica During the Nomentioning

confidence: 99%

“…Launched in February 2013, the SARAL/AltiKa mission carries the first Ka-band altimeter ever flown [1]. The primary mission objective is the observation of the oceanic mesoscales, as well as coastal oceanography, global and regional sea level monitoring, data assimilation and operational oceanography.…”

Section: Introductionmentioning

confidence: 99%

The Benefits of the Ka-Band as Evidenced from the SARAL/AltiKa Altimetric Mission: Quality Assessment and Unique Characteristics of AltiKa Data

et al. 2018

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Abstract:The India-France SARAL/AltiKa mission is the first Ka-band altimetric mission dedicated to oceanography. The mission objectives are primarily the observation of the oceanic mesoscales but also include coastal oceanography, global and regional sea level monitoring, data assimilation, and operational oceanography. The mission ended its nominal phase after 3 years in orbit and began a new phase (drifting orbit) in July 2016. The objective of this paper is to provide a state of the art of the achievements of the SARAL/AltiKa mission in terms of quality assessment and unique characteristics of AltiKa data. It shows that the AltiKa data have similar accuracy at the centimeter level in term of absolute water level whatever the method (from local to global) and the type of water surfaces (ocean and lakes). It shows also that beyond the fact that AltiKa data quality meets the expectations and initial mission requirements, the unique characteristics of the altimeter and the Ka-band offer unique contributions in fields that were previously not fully foreseen.

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The SARAL/AltiKa Altimetry Satellite Mission

Cited by 145 publications

References 4 publications

Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall

Coral mortality induced by the 2015–2016 El-Niño in Indonesia: the effect of rapid sea level fall

Monitoring Sea Level in the Coastal Zone with Satellite Altimetry and Tide Gauges

The Benefits of the Ka-Band as Evidenced from the SARAL/AltiKa Altimetric Mission: Quality Assessment and Unique Characteristics of AltiKa Data

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