Sensitivity of Altimeter Wave Height Assessment to Data Selection

Quartly, GD and Kurekin, A 2020 Sensitivity of Altimeter Wave Height Assessment to Data Selection. Remote Sensing, 12 (16). 2608.

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Thispaperaddressestheissueofhowtheselectionofbuoysandthecalculationofaltimeter averages affect the metrics characterising the errors of altimetric wave height estimates. The use of a 51-point median reduces the sensitivity to occasional outliers, but the quality of this measure can be improved by demanding that there is a minimum number of valid measurements. This had a marked impact in both the open ocean and the coastal zone. It also affected the relative ordering of algorithms’ performances, as some fared poorly when a representative value was gleaned from a single waveform inversion, but had a much better ranking when a minimum of 20 values were used. Validation procedures could also be improved by choosing altimeter-buoy pairings that showed a good consistency. This paper demonstrated an innovative procedure using the median of the differentretrackersanalysed,whichcanbeeasilyextendedtootherdatavalidationexercises. Thisled to improved comparison statistics for all algorithms in the open ocean, with many showing errors less than 0.2 m, but there was only one strong change in the relative performance of the 11 Jason-3 retrackers. For Sentinel-3A, removing the inconsistent coastal buoys showed that all of the new algorithms had similar errors of just over 0.2 m. Thus, although improvements were found in the procedure usedforthe SeaState RoundRobinexercise, the relative rankingsforthe buoycalibrations are mostly unaffected.

Item Type: Publication - Article
Additional Keywords: altimeter; validation; buoys; ocean; coastal zone; data-flagging; sensitivity studies; Jason-3; Sentinel-3A
Divisions: Plymouth Marine Laboratory > National Capability categories > NERC Earth Observation Data Acquisition & Analysis Service (NEODAAS)
Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: S Hawkins
Date made live: 13 Aug 2020 11:27
Last Modified: 13 Aug 2020 11:28

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