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AVHRR-and-VIIRS CoastWatch SST Readme

AVHRR-and-VIIRS CoastWatch SST Readme



The AVHRR-and-VIIRS CoastWatch SST products supply users with operational satellite data, processed using TeraScan software and CoastWatch utilities. All data are contained in subdirectories named according to the date, time (UTC), satellite, and ground station for the satellite pass. Each directory contains a number of files:

CoastWatch product data in Hierarchical Data Format (HDF). Large files approximately 40-60 Mb are full pass swath projection data, and are mainly for use by research personnel at NOAA. Smaller files approximately 1-10 Mb in size are mapped projection data. These are the standard CoastWatch product files viewable in CDAT.
JPEG browse image for the full pass swath projection.
Data processing log file showing details on ingest, automatic navigation, SST equations and coefficients, and so on.
Information file containing pass parameters such as dimensions, date, time, spacecraft attitude, and GCP mesh coordinates.
The mapped HDF data is divided into files for a number of CoastWatch regions of interest, where each file contains multiple data variables. Mapped HDF files may be downloaded and viewed using the CoastWatch Utilities software, which includes the graphical CoastWatch Data Analysis Tool (CDAT), available from:

Directory Naming Conventions

Directories are named according to the date, UTC time, satellite, and ground station for the satellite pass as in the following template:

Full year with century
Julian day [001-366]
Hour and minute in Greenwich (UTC) time
Satellite code:
m01 = Metop-1
m02 = Metop-2
n15 = NOAA-15
npp = SNPP
n20 = NOAA-20
Ground station where the data was captured:
mo = Monterey, CA
gc = Gilmore Creek, AK
wi = Wallops Island, VA
eb = Ewa Beach, HI
mi = Miami, FL

Data File Naming Conventions

Both mapped and swath HDF product files are named using the same convention with the following template:

Full year with century
Julian day [001-366]
Hour and minute in Greenwich (UTC) time
Satellite code (see above for examples)
CoastWatch region code
File format
The current CoastWatch region codes are as follows:

Region code Region description Projection type Map projection
gc Gilmore Creek, AK swath n/a
aa Alaska Sitka mapped Polar stereographic
ax Alaska south mapped Polar stereographic
ay Alaska west mapped Polar stereographic
az Alaska north mapped Polar stereographic
mi Miami, FL swath n/a
ce Caribbean east mapped Mercator
cw Caribbean west mapped Mercator
mr Gulf of Mexico mapped Mercator
wa West Coast Acapulco mapped Mercator
wi Wallops Island, VA swath n/a
er East Coast north mapped Mercator
sr East Coast south mapped Mercator
sb East Coast Bermuda mapped Mercator
gr Great Lakes regional mapped Mercator
eb Ewa Beach, HI swath n/a
hr Hawaii regional mapped Mercator
mo Monterey, CA swath n/a
wj West Coast Baja mapped Mercator
wn West Coast north mapped Mercator
ws West Coast south mapped Mercator
sl Great Salt Lake mapped Mercator

Variable Naming Conventions

Each HDF data file contains multiple data variables stored using the HDF Scientific Data Sets (SDS) model. Each variable is named according to the data that it represents as follows:

AVHRR channel 1 albedo (%)
AVHRR channel 2 albedo (%)
AVHRR channel 3a albedo (%)
AVHRR channel 3 brightness temperature (deg C)
AVHRR channel 4 brightness temperature (deg C)
AVHRR channel 5 brightness temperature (deg C)
Moisture corrected sea-surface-temperature (deg C)
8-bit CLAVR ocean cloud mask:
Bit 1: Reflective Gross Cloud Test
Bit 2: Reflectance Uniformity Test
Bit 3: Reflectance Ratio Cloud Test
Bit 4: Channel 3 Albedo Test
Bit 5: Thermal Uniformity Test
Bit 6: Four Minus Five Test
Bit 7: Thermal Gross Cloud Test
Bit 1: Thermal Gross Cloud Test
Bit 2: Thermal Uniformity Test
Bit 3: Uniform Low Stratus Test
Bit 4: Four Minus Five Test
Bit 5: Cirrus Test
Bit 6: Channel 3B Albedo Test
Bit 7: Channel 3B Albedo Uniformity Test
Satellite zenith angle (degrees)
Solar zenith angle (degrees)
Relative azimuth angle (degrees)
8-bit graphics layers:
Bit 1: Fill flag
Bit 2: Latitude/longitude grid
Bit 3: Coastline and political geography lines
Bit 4: Land/water flag
Bits 5-8: Unused


For questions or comments regarding these products, please contact