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High Resolution Sea Surface Temperature from the Advanced Very-High Resolution Radiometer
Program: NOAA Polar-orbiting Operational Environmental Spacecraft
Spacecraft: NOAA-17 and NOAA-18
Sensor: Advanced Very High Resolution Radiometer (AVHRR)
Data Stream: High Resolution Picture Transmission (HRPT)
Primary Geophysical Parameter: Sea surface temperature (SST)
Nominal Accuracy: 0.7 degrees Celsius (C)
Spatial grid: 0.0125 degrees longitude by 0.0125 degrees latitude, geographic
Spatial coverage: West Coast of North America
Temporal Coverage: Last 60 days + (depending on storage space)
High-resolution sea surface temperature derived from the AVHRR sensors carried aboard the NOAA Polar-orbiting Operational Environmental Spacecraft (POES) is one of the flagship products of the NOAA CoastWatch program. These data are particularly useful for West Coast resource managers, fishing men and women, and the interested public, as they allow the detection and measurement of many of the dominant physical oceanic features in the California Current System.
CoastWatch offers sea surface temperature (SST) data from the Advanced Very High Resolution Radiometer (AVHRR) instrument aboard NOAA's Polar Operational Environmental Satellites (POES). Two satellites are currently in use, NOAA-17 and NOAA-18, providing SST images four to eight times daily. The AVHRR sensor is a five channel sensor comprised of two visible radiance channels and three infrared radiance channels. During daytime satellite passes, all five radiance channels are used. During nighttime passes, only the infrared radiance channels are used.
The satellites download data to a NOAA National Weather Service ground receiving station in Monterey, CA, via High Resolution Picture Transmission (HRPT) for the West Coast of North America at approximately 1.47 km resolution. The processing of sea surface temperature by NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) from these radiance measurements uses the non-linear sea surface temperature (NLSST) algorithm detailed in Walton et al., 1998. SST measurements are generally accurate to within 0.7 degrees Celsius. Ongoing calibration and validation efforts by NOAA satellites and information provide for continuity of quality assessment and algorithm integrity (e.g., Li et al., 2001a and Li et al., 2001b). In addition, the CoastWatch West Coast Regional Node (WCRN) runs monthly validation tests for all SST data streams using data from the NOAA National Weather Service and National Data Buoy Center.
The data are cloud screened using the CLAVR-1 method developed and maintained by NOAA Satellites and Information (e.g., Stowe et al., 1999). The data are mapped to an equal angle grid (0.0125 degrees latitude by 0.0125 degrees longitude) using a simple arithmetic mean to produce individual and composite images of various durations (e.g., 1, 3, 8, 14-day).
Despite our best efforts, a small percentage of clouds are not correctly identified by the cloud-screening algorithm. Such leakage, or contamination, is much worse at nighttime than it is in the day, when the visible channels are available. Exacerbating this is the high number of clear ocean pixels that are identified as clouds and thus incorrectly removed from the ocean temperature fields. This continues to be an area of much effort at both regional and national levels.
Despite our best efforts, incorrect data may often appear within near real time data sets. NOAA CoastWatch accepts no liability for use of these data products. It is recommended that these products NOT be used for navigation.
If this data is used for presentation or publication, please acknowledge the NOAA CoastWatch Program and the NOAA NWS Monterey Regional Forecast Office.
References and suggested citations:
Li, X., W. Pichel, E. Maturi, P. Clemente-Colón, and J. Sapper, 2001a. Deriving the operational nonlinear multi-channel sea surface temperature algorithm coefficients for NOAA-15 AVHRR/3, Int. J. Remote Sens., Volume 22, No. 4, 699 - 704.
Li, X, W. Pichel, P. Clemente-Colón, V. Krasnopolsky, and J. Sapper, 2001b. Validation of coastal sea and lake surface temperature measurements derived from NOAA/AVHRR Data, Int. J. Remote Sens., Vol. 22, No. 7, 1285-1303.
Stowe, L. L., P. A. Davis, and E. P. McClain, 1999. Scientific basis and initial evaluation of the CLAVR-1 global clear/cloud classification algorithm for the advanced very high resolution radiometer. J. Atmos. Oceanic Technol., 16, 656-681.
Walton C. C., W. G. Pichel, J. F. Sapper, D. A. May, 1998. The development and operational application of nonlinear algorithms for the measurement of sea surface temperatures with the NOAA polar-orbiting environmental satellites, J. Geophys. Res., 103: (C12) 27999-28012.