Validating landsat analysis ready data for nearshore sea surface temperature monitoring in the Northeast Pacific
Date
2024
Authors
Wachmann, Alena
Starko, Samuel
Neufeld, Christopher J.
Costa, Maycira
Journal Title
Journal ISSN
Volume Title
Publisher
Remote Sensing
Abstract
In the face of global ocean warming, monitoring essential climate variables from space is necessary for understanding regional trends in ocean dynamics and their subsequent impacts on ecosystem health. Analysis Ready Data (ARD), being preprocessed satellite-derived products such as Sea Surface Temperature (SST), allow for easy synoptic analysis of temperature conditions given the consideration of regional biases within a dynamic range. This is especially true for SST retrieval in thermally complex coastal zones. In this study, we assessed the accuracy of 30 m resolution Landsat ARD Surface Temperature products to measure nearshore SST, derived from Landsat 8 TIRS, Landsat 7 ETM+, and Landsat 5 TM thermal bands over a 37-year period (1984–2021). We used in situ lighthouse and buoy matchup data provided by Fisheries and Oceans Canada (DFO). Excellent agreement (R2 of 0.94) was found between Landsat and spring/summer in situ SST at the farshore buoy site (>10 km from the coast), with a Landsat mean bias (root mean square error) of 0.12 °C (0.95 °C) and a general pattern of SST underestimation by Landsat 5 of −0.28 °C (0.96 °C) and overestimation by Landsat 8 of 0.65 °C (0.98 °C). Spring/summer nearshore matchups revealed the best Landsat mean bias (root mean square error) of −0.57 °C (1.75 °C) at 90–180 m from the coast for ocean temperatures between 5 °C and 25 °C. Overall, the nearshore image sampling distance recommended in this manuscript seeks to capture true SST as close as possible to the coastal margin—and the critical habitats of interest—while minimizing the impacts of pixel mixing and adjacent land emissivity on satellite-derived SST.
Description
Thank you to the University of Victoria and the Spectral Remote Sensing Lab for providing computational facilities for this study. S.S would like to also thank/acknowledge the Forrest Research Foundation for funding. This research was originally conducted as part of an honours thesis (2022) by A.W. towards a BSc Honours in Geography at the University of Victoria, BC, Canada. Thank you to Alex Guyn for his support during the early stages of the research and initial investigation of the data. Thank you to Lianna Gendall for her advice and mentorship. Thank you to NASA and the USGS for acquiring and providing spaceborne data and Fisheries and Oceans Canada for their in situ monitoring and dissemination of oceanographic data. Special thanks to Andrea Jans Van Rensburg and Connor Dean for their camaraderie during late nights in the Geomatics Lab and GIS troubleshooting.
Keywords
Landsat, Analysis Ready Data, nearshore, sea surface temperature (SST), coastal ecosystems
Citation
Wachmann, A., Starko, S., Neufeld, C. J., & Costa, M. (2024). Validating landsat analysis ready data for nearshore sea surface temperature monitoring in the Northeast Pacific. Remote Sensing, 16(5), 920. https://doi.org/10.3390/rs16050920