Abstract
Sea surface temperature (SST) is observed by a constellation of sensors, and SST retrievals are commonly combined into gridded SST analyses and climate data records (CDRs). Differential biases between SSTs from different sensors cause errors in such products, including feature artefacts. We introduce a new method for reducing differential biases across the SST constellation, by reconciling the brightness temperature (BT) calibration and SST retrieval parameters between sensors. We use the Advanced Along-Track Scanning Radiometer (AATSR) and the Sea and Land Surface Temperature Radiometer (SLSTR) as reference sensors, and the Advanced Very High Resolution Radiometer (AVHRR) of the MetOp-A mission to bridge the gap between these references. Observations across a range of AVHRR zenith angles are matched with dual-view three-channel skin SST retrievals from the AATSR and SLSTR. These skin SSTs act as the harmonization reference for AVHRR retrievals by optimal estimation (OE). Parameters for the harmonized AVHRR OE are iteratively determined, including BT bias corrections and observation error covariance matrices as functions of water-vapor path. The OE SSTs obtained from AVHRR are shown to be closely consistent with the reference sensor SSTs. Independent validation against drifting buoy SSTs shows that the AVHRR OE retrieval is stable across the reference-sensor gap. We discuss that this method is suitable to improve consistency across the whole constellation of SST sensors. The approach will help stabilize and reduce errors in future SST CDRs, as well as having application to other domains of remote sensing.
Highlights
Sea surface temperature (SST) is the temperature of sea-water measured at or close to the air-sea interface
Without determination of optimal estimation (OE) parameters, SST from MTA are biased relative to the reference SSTs from Advanced Along-Track Scanning Radiometer (AATSR) by an average of 0.23 K
SST harmonization is required in order for MTA to function as a bridging reference sensor from AATSR to Sea and Land Surface Temperature Radiometer (SLSTR)
Summary
Sea surface temperature (SST) is the temperature of sea-water measured at or close to the air-sea interface. An analysis of the field of SST across the Pacific Ocean was first obtained by infrared (IR) remote sensing from space in 1970 [1] and in the same year was published the concept of better retrieving such SST estimates using two channels that are differently sensitive to atmospheric conditions [2]. SST products informed by satellite observations have become widely used. Scientific applications in climatology and marine ecology demand SST information that is highly consistent and comparable over time and space. Understanding and monitoring the impact of thermal stress on coral reefs benefits from long time series of stable SST observations, because corals are long-lived and adapted to the marine climate of past decades [4]. Increasing sophistication of retrieval methods [5,6,7] has delivered reducing SST uncertainty [8,9] and greater spatio-temporal resolution of SST analyses (analyses are gap-filled estimates of the SST field) [10,11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
