Estimation of Sea Ice Freeboard from SARAL/AltiKa Data

Maheshwari, Megha; Mahesh, C.; Rajkumar, Kamaljit Singh; Pallipad, Jayaprasad; Rajak, D. Ram; Oza, Sandip R.; Kumar, Raj; Sharma, Rashmi

doi:10.1080/01490419.2015.1005782

Cited by 11 publications

(11 citation statements)

References 17 publications

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“…The airborne OIB and CryoVEx data are primarily used to evaluate the satellite radar freeboard, to investigate penetration depths of both Ku-and Ka-band radars and the potential for snow-depth retrieval [60,81,92,100,129] and to examine the sensitivity to the choice of using different retrackers [56,62]. These studies consistently conclude that the predominant signal from Ku-band satellite radars such as CryoSat-2 and Envisat corresponds to the reflections from close to the snow-ice boundary.…”

Section: Freeboardmentioning

confidence: 87%

“…A wider range of conclusions was found for the Ka-band radar altimeter (SARAL/AltiKa). Guerreiro et al [92] concluded that AltiKa's signals corresponded to a reflection at the air-snow surface, Armitage and Ridout [81] concluded that they were almost half-way between the air-snow and snow-ice surface, and Maheshwari et al [129] concluded that they were at the snow-ice surface. Lawrence et al [100] found a surface-dependent bias of the AltiKa radar freeboard against airborne snow freeboard.…”

Section: Freeboardmentioning

confidence: 99%

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Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

et al. 2019

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Spaceborne radar altimeters record echo waveforms over all Earth surfaces, but their interpretation and quantitative exploitation over the Arctic Ocean is particularly challenging. Radar returns may be from all ocean, all sea ice, or a mixture of the two, so the first task is the determination of which surface and then an interpretation of the signal to give range. Subsequently, corrections have to be applied for various surface and atmospheric effects before making a comparison with a reference level. This paper discusses the drivers for improved altimetry in the Arctic and then reviews the various approaches that have been used to achieve the initial classification and subsequent retracking over these diverse surfaces, showing examples from both LRM (low resolution mode) and SAR (synthetic aperture radar) altimeters. The review then discusses the issues concerning corrections, including the choices between using other remote-sensing measurements and using those from models or climatology. The paper finishes with some perspectives on future developments, incorporating secondary frequency, interferometric SAR and opportunities for fusion with measurements from laser altimetry or from the SMOS salinity sensor, and provides a full list of relevant abbreviations.

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Section: Freeboardmentioning

confidence: 87%

Section: Freeboardmentioning

confidence: 99%

Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

et al. 2019

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“…The airborne OIB and CryoVEx data are primarily used to evaluate the satellite radar freeboard, to investigate penetration depths of both Ku-and Ka-band radars and the potential for snow-depth retrieval Maheshwari et al, 2015;Guerreiro et al, 2016;Connor et al, 2009;Lawrence et al, 2018), and to examine the sensitivity to the choice of using different re-trackers (Kurtz et al, 2014;Ricker et al, 2014). These studies consistently conclude that the predominant signal from Ku-band satellite radars such as CryoSat-2 and Envisat corresponds to reflections from close to the snow-ice boundary.…”

Section: Freeboardmentioning

confidence: 88%

Review of Radar Altimetry Techniques over the Arctic Ocean: Recent Progress and Future Opportunities for Sea Level and Sea Ice Research

Quartly

Rinne

Passaro

et al. 2018

Preprint

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Abstract. There are numerous needs for monitoring sea level and sea ice in the Arctic, ranging from concern about changes in ice cover being both an indicator and a driver of long-term climate change to shipping interest in alternative routes and the associated risks to the safety of vessels and crew. Furthermore, sea level relative to the geoid allows us to quantify the geostrophic circulation, including any changes in the flow. Radar altimeters provide an important means of quantifying changes in sea level and sea-ice thickness, although there are increased complexities in the interpretation of their data over such a variable surface. This paper reviews the techniques for deriving useful geophysical information over a mix of leads and ice floes, covering the approaches for both conventional (low rate mode) altimetry and the newer delay-Doppler (Synthetic Aperture Radar) instruments. It discusses the challenges in discriminating the returns from different surfaces, the retracking approaches and the corrections required. The review finishes with a look ahead to how new technologies, analyses and understanding may be expected to improve the monitoring in this critical environment.

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“…Sea Ice advisory and utilization of RISAT-1 and SARAL AltiKa derived free-board Climatic Sea Ice Occurrence Probability (SIOP) and sea ice type data has been operationalized for safer ship navigation by ISRO, Ahmedabad (Maheshwari et al, 2015;Rajak et al, 2014;Rajak et al, 2015). Results of these studies can be visualised on the website (SAC, 2015).…”

Section: Ship Navigation Advisory Effortsmentioning

confidence: 99%

Polar Ice Sheet and Glacier Studies-Indian Efforts in last Five Years

Thakur

2017

Proceedings of the Indian National Science Academy

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Indian scientists have been involved in studies of cryosphere in Polar Regions from past 35 years. For continuous monitoring and expanding research in the fields of atmospheric science, geosciences, glaciology, environmental sciences, etc. specific to these regions, the ESSO -National Centre for Antarctic and Ocean Research (ESSO-NCAOR) has established three permanent research stations in Antarctica. This paper addresses efforts by Indian scientists in last five years in cryospheric studies on the Antarctica using remote sensing data. Inventories of Antarctic glaciers and ice sheet features prepared by Indian researchers have facilitated for detailed long-term studies on glacier dynamics, sea ice, fluctuations of the continental ice margin and snouts of glaciers. For safe and optimal navigation of ships, a sea ice advisory has been also set up. This paper also addresses recent efforts of using high-resolution earth observation satellite data which were acquired for geospatial mapping of cryospheric features and glacial landforms and for delineation of wind induced snow deposition zones in part of the Antarctica. Spatiotemporal dynamics of surface melting over Antarctic was further studied by using moderate resolution satellite data.

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Estimation of Sea Ice Freeboard from SARAL/AltiKa Data

Cited by 11 publications

References 17 publications

Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

Review of Radar Altimetry Techniques over the Arctic Ocean: Recent Progress and Future Opportunities for Sea Level and Sea Ice Research

Polar Ice Sheet and Glacier Studies-Indian Efforts in last Five Years

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