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Technical Note

Comparison of a Smartfin with an Infrared Sea Surface Temperature Radiometer in the Atlantic Ocean

1
Centre for Geography and Environmental Science, College of Life and Environmental Sciences, Penryn Campus, University of Exeter, Cornwall TR10 9FE, UK
2
Plymouth Marine Laboratory, Plymouth, Devon PL1 3DH, UK
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Ocean and Earth Science, Faculty of Environmental and Life Sciences, Waterfront Campus, University of Southampton, Southampton, Hampshire SO14 3ZH, UK
4
Scripps Institution of Oceanography, University of California, San Diego, CA 92037, USA
5
Department of Earth and Ocean Sciences, University of North Carolina Wilmington, Wilmington, NC 28403-5944, USA
6
Department of Marine and Environmental Sciences, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
7
National Centre for Earth Observation, Plymouth Marine Laboratory, Plymouth, Devon PL1 3DH, UK
*
Author to whom correspondence should be addressed.
Academic Editor: Csaba Centeri
Remote Sens. 2021, 13(5), 841; https://doi.org/10.3390/rs13050841
Received: 2 February 2021 / Revised: 16 February 2021 / Accepted: 18 February 2021 / Published: 24 February 2021
(This article belongs to the Special Issue Feature Paper Special Issue on Ocean Remote Sensing)
The accuracy and precision of satellite sea surface temperature (SST) products in nearshore coastal waters are not well known, owing to a lack of in-situ data available for validation. It has been suggested that recreational watersports enthusiasts, who immerse themselves in nearshore coastal waters, be used as a platform to improve sampling and fill this gap. One tool that has been used worldwide by surfers is the Smartfin, which contains a temperature sensor integrated into a surfboard fin. If tools such as the Smartfin are to be considered for satellite validation work, they must be carefully evaluated against state-of-the-art techniques to quantify data quality. In this study, we developed a Simple Oceanographic floating Device (SOD), designed to float on the ocean surface, and deployed it during the 28th Atlantic Meridional Transect (AMT28) research cruise (September and October 2018). We attached a Smartfin to the underside of the SOD, which measured temperature at a depth of ∼0.1 m, in a manner consistent with how it collects data on a surfboard. Additional temperature sensors (an iButton and a TidbiT v2), shaded and positioned a depth of ∼1 m, were also attached to the SOD at some of the stations. Four laboratory comparisons of the SOD sensors (Smartfin, iButton and TidbiT v2) with an accurate temperature probe (±0.0043 K over a range of 273.15 to 323.15 K) were also conducted during the AMT28 voyage, over a temperature range of 290–309 K in a recirculating water bath. Mean differences (δ), referenced to the temperature probe, were removed from the iButton (δ=0.292 K) and a TidbiT v2 sensors (δ=0.089 K), but not from the Smartfin, as it was found to be in excellent agreement with the temperature probe (δ=0.005 K). The SOD was deployed for 20 min periods at 62 stations (predawn and noon) spanning 100 degrees latitude and a gradient in SST of 19 K. Simultaneous measurements of skin SST were collected using an Infrared Sea surface temperature Autonomous Radiometer (ISAR), a state-of-the-art instrument used for satellite validation. Additionally, we extracted simultaneous SST measurements, collected at slightly different depths, from an underway conductivity, temperature and depth (CTD) system. Over all 62 stations, the mean difference (δ) and mean absolute difference (ϵ) between Smartfin and the underway CTD were −0.01 and 0.06 K respectively (similar results obtained from comparisons between Smartfin and iButton and Smartfin and TidbiT v2), and the δ and ϵ between Smartfin and ISAR were 0.09 and 0.12 K respectively. In both comparisons, statistics varied between noon and predawn stations, with differences related to environmental variability (wind speed and sea-air temperature differences) and depth of sampling. Our results add confidence to the use of Smartfin as a citizen science tool for evaluating satellite SST data, and data collected using the SOD and ISAR were shown to be useful for quantifying near-surface temperature gradients. View Full-Text
Keywords: sea surface temperature; Smartfin; thermal radiometry; remote sensing; validation; citizen science; surfers sea surface temperature; Smartfin; thermal radiometry; remote sensing; validation; citizen science; surfers
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MDPI and ACS Style

Brewin, R.J.W.; Wimmer, W.; Bresnahan, P.J.; Cyronak, T.; Andersson, A.J.; Dall’Olmo, G. Comparison of a Smartfin with an Infrared Sea Surface Temperature Radiometer in the Atlantic Ocean. Remote Sens. 2021, 13, 841. https://doi.org/10.3390/rs13050841

AMA Style

Brewin RJW, Wimmer W, Bresnahan PJ, Cyronak T, Andersson AJ, Dall’Olmo G. Comparison of a Smartfin with an Infrared Sea Surface Temperature Radiometer in the Atlantic Ocean. Remote Sensing. 2021; 13(5):841. https://doi.org/10.3390/rs13050841

Chicago/Turabian Style

Brewin, Robert J.W., Werenfrid Wimmer, Philip J. Bresnahan, Tyler Cyronak, Andreas J. Andersson, and Giorgio Dall’Olmo. 2021. "Comparison of a Smartfin with an Infrared Sea Surface Temperature Radiometer in the Atlantic Ocean" Remote Sensing 13, no. 5: 841. https://doi.org/10.3390/rs13050841

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