Comparison of the X-TRACK altimetry estimated currents with moored ADCP and HF radar observations on the West Florida Shelf

Liu, Yonggang; Weisberg, Robert H.; Vignudelli, Stefano; Roblou, L.; Merz, Clifford R.

doi:10.1016/j.asr.2011.09.012

Cited by 55 publications

(54 citation statements)

References 100 publications

(136 reference statements)

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“…Chapman et al 1997, Kohut et al 2012. These results are also consistent with Liu et al (2012), applying similar approaches but to Topex/Poseidon and Jason-1 missions and using dedicated coastal-oriented altimeter corrections in the West Florida Shelf.…”

Section: Resultssupporting

confidence: 91%

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

et al. 2015

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We present an initial assessment of SARAL/AltiKa data in the coastal band. The study focuses on the Ibiza Channel where the north-south water exchanges play a key role in controlling the circulation variability in the Western Mediterranean. In this area, the track 16 of SARAL/AltiKa Downloaded by [New York University] at 03:55 27 May 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT2 intercepts the domain covered by a coastal high-frequency (HF) radar system, which provides surface currents with a range up to 60 km. We evaluate the performance of the SARAL/AltiKa Ssalto/Duacs delayed-time along-track products when compared to the HF radar surface velocity fields. SARAL/AltiKa data are retrieved at a distance of only 7 km from the coast putting in evidence the emerging capabilities of new altimeter.The derived velocities resolved the general features of the seasonal mesoscale variability with reasonable agreement with HF radar fields (significant correlations of 0.54), However, some discrepancies appear, which might be caused by ageostrophic velocities as well as inaccurate corrections and editing in the altimeter data.Root mean square (rms) differences between the estimated SARAL/AltiKa and the HF radar velocities are of about 13 cm/s. These results are consistent with recent studies in other parts of the ocean applying similar approaches to Topex/Poseidon and Jason-1 missions and using coastal altimeter corrections.

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Section: Resultssupporting

confidence: 91%

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

et al. 2015

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“…In our study we observe that winds directly impact on the displacement of the thermal fronts in satellite imagery, causing disturbances that cannot be explained by geostrophic currents. It can be expected that the difference between altimetry-derived geostrophic velocity and (wind-driven + geostrophic) currents obtained from satellite imagery can give information on wind-driven currents in the surface layers for understanding its relationship with wind forcing [31,36]. This information is also very valuable as wind drift currents are important for many oceanographic tasks: e.g., for oil spill tracking, study of river plume dynamics, or interpretation of coastal radar data [83,84].…”

Section: Discussionmentioning

confidence: 99%

“…This includes the decrease of quality of the wet tropospheric correction, mapping procedure, mean dynamic topography, and difficulties in the description of barotropic sea level variability [2,[27][28][29][30]. Third, altimetry-derived velocities are geostrophic and represent only a part, also very important, of the current velocity [31]. Wind-driven currents are another important part of the surface currents, and should be additionally described using different assumptions [32][33][34][35] to reconstruct total surface currents on the basis of satellite altimetry.…”

Section: Introductionmentioning

confidence: 99%

Reconstructing Large- and Mesoscale Dynamics in the Black Sea Region from Satellite Imagery and Altimetry Data—A Comparison of Two Methods

2018

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Two remote sensing methods, satellite altimetry and 4D-Var assimilation of satellite imagery, are used to compute surface velocity fields in the Black Sea region. Surface currents derived from the two methods are compared for several cases with intense mesoscale and large-scale dynamics during low wind conditions. Comparison shows that the obtained results coincide well quantitatively and qualitatively. However, satellite imagery provides more reasonable results on the spatial variability of coastal dynamics than altimetry data. In particular, this is related to the reconstruction of eddy coastal dynamics, such as Black Sea near-shore anticyclones. Current streamlines in these eddies are not closed near the coast in altimetry data, which we relate to the extrapolation during mapping procedure in the absence of coastal along-track measurements. On the other hand, in offshore areas, imagery-derived currents can be underestimated due to the absence of thermal contrasts and smoothing during the procedure of the 4D-Var assimilation. Wind drift currents are another source of inconsistency, as their impact is directly observed in satellite imagery but absent in altimetry data. The advantage of the 4D-Var method for reconstructing coastal dynamics is used to compute surface currents in the Marmara Sea on the base of 250 m resolution Modis optical data. The results reveal the very complex dynamics of the basin, with a large number of mesoscale and sub-mesoscale eddies. 4D-Var assimilation of Modis imagery is used to obtain information about dynamic characteristics of these small eddies with radiuses of 4-10 km.

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“…A number of initiatives have been made in the last decade to improve the accuracy and availability of altimeter data in the coastal zone. They are applied to along-track measurements (Vignudelli et al, 2005;Roblou et al, 2007;Brown, 2010;Liu et al, 2012), including the use of coastal-oriented corrections and the review of the data recovery strategies near the coast (Vignudelli et al, 2003(Vignudelli et al, , 2005(Vignudelli et al, , 2011 http://dx.doi.org/10.1016/j.asr.2014.12.039 0273-1177/Ó 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Heavy Guadalquivir River discharge detection with satellite altimetry: The case of the eastern continental shelf of the Gulf of Cadiz (Iberian Peninsula)

Gómez-Enri

Escudier

Pascual

et al. 2015

Advances in Space Research

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In situ water levels in the Guadalquivir River estuary mouth show the effect of strong river freshwater discharges on the monthly means of the sea level on a yearly basis. Accurate altimeter products oriented toward coastal zones are increasing the number of potential applications at different spatiotemporal scales. The present work is focused on the analysis of the sea-level variability in the eastern shelf of the Gulf of Cadiz (between North Africa and the southwestern side of the Iberian Peninsula), adjacent to the Guadalquivir River estuary. Sixteen years (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) of along-track and standard AVISO maps of sea-level anomalies (SLAs) have been used to generate a new high-resolution product with increased spatiotemporal resolution. The use of a bathymetry constraint and smaller correlation scales in the methodology developed to generate high-resolution altimeter products improves the characterization of the mesoscale signals in the coastal strip adjacent to the estuary due to strong river freshwater discharges. This has been confirmed by the analysis of along-track SLA data in the vicinity of the estuary. The daily evolution (2 weeks) of the sea level obtained in the event of December 2009 might be related to the river plume extension observed by optical Moderate Resolution Imaging Spectrometer (MODIS) images. The spatiotemporal distribution of the altimeter tracks available in the study area might compromise the mapping capabilities to capture coastal and fine-scale features.

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Comparison of the X-TRACK altimetry estimated currents with moored ADCP and HF radar observations on the West Florida Shelf

Cited by 55 publications

References 100 publications

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

Reconstructing Large- and Mesoscale Dynamics in the Black Sea Region from Satellite Imagery and Altimetry Data—A Comparison of Two Methods

Heavy Guadalquivir River discharge detection with satellite altimetry: The case of the eastern continental shelf of the Gulf of Cadiz (Iberian Peninsula)

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