J-OFURO3 Best Track Sea Surface Temperature (BTSST)

The J-OFURO3 BTSST dataset provides satellite-derived sea surface temperature (SST) data associated with tropical cyclone (TC) passages. It combines TC best-track data from the Japan Meteorological Agency (JMA) with SST data from the Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations 3 (J-OFURO3), version 1.2. J-OFURO3 is a third-generation dataset of ocean surface fluxes based primarily on satellite observations (Tomita et al., 2019). Because SST is a key input for estimating ocean surface heat fluxes, J-OFURO3 also provides its own SST product. The J-OFURO3 SST is constructed as the ensemble median of multiple global Level-3 and Level-4 SST products. A total of 19 source products are used over the period from 1988 to 2022. Nakada and Tomita (2025) compared SST responses to TC passages among several SST products and showed that the J-OFURO3 SST exhibited the smallest spatiotemporal variations in SST bias among the products examined. This characteristic makes the J-OFURO3 SST particularly suitable for investigating SST changes associated with TC passages over multidecadal periods. J-OFURO3 BTSST includes two types of SST-related variables at each storm location: pre-passage SST (pre_sst and pre_srsst) and SST change (sstc). Both pre_sst and pre_srsst are defined as the area-averaged SST over the period 15–3 days before TC passage. For pre_sst, SST is averaged within a 2° × 2° area centered on the storm center. For pre_srsst, SST is averaged over a storm-relative area extending 0–200 km to the right of the TC track and ±100 km in the along-track direction (srsst denotes storm-relative SST). The variable sstc represents SST change, or SST cooling, associated with TC passage. It is defined as the difference between the area-averaged SST after and before TC passage. For different research purposes, three definitions of sstc are provided: (1) the mean SST 1–2 days after passage minus pre_sst; (2) the same as (1), but using the mean SST 0–1 day after passage; and (3) the same as (1), but using pre_srsst instead of pre_sst. For each definition, the post-passage SST is averaged over the same area used to calculate the corresponding pre-passage SST. In general, TC-induced SST cooling reaches its maximum approximately 1–2 days after passage and tends to be stronger on the right-hand side of the TC track. Therefore, type 1 or type 3 sstc might be more suitable for studies focusing on the ocean response to TC passage. In contrast, type 2 might be more suitable for studies of TC–ocean interactions, because a moving TC generally rarely remains over the same location for 1–2 days. Multiple versions of sstc, pre_sst, and pre_srsst are provided, calculated from SST fields with or without the removal of major large-scale variability components: the seasonal cycle, long-term trend, El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North Pacific Gyre Oscillation (NPGO). The seasonal cycle is represented by the daily climatology over the period 1988–2022. The long-term trend is estimated using a least-squares linear fit. The ENSO, PDO, and NPGO components are estimated by linearly regressing SST onto the Niño 3.4, PDO, and NPGO indices, respectively, obtained from NOAA.