N: 59 S: -59 E: -160 W: 80
Description
Himawari-8 (H08) was launched on 7 October 2014 into its nominal position at 140.7-deg E, and declared operational on 7 July 2015. The Advanced Himawari Imager (AHI; largely identical to GOES-R/ABI) is a 16 channel sensor, of which five (3.9, 8.4, 10.3, 11.2, and 12.3 um) are suitable for SST. Accurate sensor calibration, image navigation and (co)registration, high spectral fidelity, and sophisticated pre-processing (geo-rectification, radiance equalization, and mapping) offer vastly enhanced capabilities for SST retrievals, over the heritage GOES-I/P and MTSAT-2 Imagers. From altitude 35,800km, H08/AHI maps SST in a Full Disk (FD) area from 80E-160W and 60S-60N, with spatial resolution 2km at nadir to 15km at view zenith angle 67-deg, with a 10-min temporal sampling. The AHI L2P (swath) SST product is derived at the native sensor resolution using NOAA's Advanced Clear-Sky Processor for Ocean (ACSPO) system. ACSPO processes every 10-min FD data, identifies good quality ocean pixels (Petrenko et al., 2010) and derives SST using the four-band (8.4, 10.3, 11.2 and 12.3um) Non-Linear SST (NLSST) regression algorithm (Petrenko et al., 2014), trained against in situ SSTs from drifting and tropical mooring buoys in the NOAA iQuam system (Xu and Ignatov, 2014). The 10-min data are subsequently collated in time, to produce 1-hr L2P product, with improved coverage, and reduced cloud leakages and image noise. The collated L2P reports SSTs and brightness temperatures (BTs) in clear-sky water pixels (defined as ocean, sea, lake or river), and fill values elsewhere. All pixels with valid SSTs are recommended for use. ACSPO files also include sun-sensor geometry, l2p_flags (day/night, land, ice, twilight, and glint flags), and NCEP wind speed. The L2P is reported in NetCDF4 GHRSST Data Specification version 2 (GDS2) format, 24 granules per day, with a total data volume 0.6GB/day. Pixel earth locations are not reported in the granules, as they remain unchanged from granule to granule. Those can be obtained using a flat lat/lon file or a Python script (see Documentation page). Per GDS2 specifications, two additional Sensor-Specific Error Statistics layers (SSES bias and standard deviation) are reported in each pixel (Petrenko et al., 2016). The H08 AHI SSTs and BTs are continuously validated against in situ data in SQUAM (Dash et al, 2010), and RTM simulation in MICROS (Liang and Ignatov, 2011). A reduced size (0.2GB/day), 0.02-deg equal-angle gridded ACSPO L3C product is available at https://podaac.jpl.nasa.gov/dataset/AHI_H08-STAR-L3C-v2.70.
Product Summary
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Variables
Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.
The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| brightness_temperature_08um6 | non L2P core field; brightness temperature for 8.6 um channel ABI Ch. 11 | kelvin | short | -32768 | -32767 to 32767 | 0.01 |
| brightness_temperature_10um4 | non L2P core field; brightness temperature for 10.4 um channel ABI Ch. 13 | kelvin | short | -32768 | -32767 to 32767 | 0.01 |
| brightness_temperature_11um2 | non L2P core field; brightness temperature for 11.2 um channel ABI Ch. 14 | kelvin | short | -32768 | -32767 to 32767 | 0.01 |
| brightness_temperature_12um3 | non L2P core field; brightness temperature for 12.3 um channel ABI Ch. 15 | kelvin | short | -32768 | -32767 to 32767 | 0.01 |
| dt_analysis | Deviation from reference SST, i.e., dt_analysis = SST - reference SST | kelvin | byte | -128 | -127 to 127 | 0.1 |
| geostationary | geostationary | N/A | int | N/A | N/A | 1 |
| l2p_flags | L2P common flags in bits 1-6 and data provider flags (from ACSPO mask) in bits 9-16: bit01 (0=IR: 1=microwave); bit02 (0=ocean; 1=land); bit03 (0=no ice; 1=ice); bits04-07 (reserved,set to 0); bit08 (0=anti-solar; 1=solar); bit09 (0=radiance valid; 1=invalid); bit10 (0=night; 1=day); bit11 (0=ocean; 1=land); bit12 (0=good quality data; 1=degraded quality data due to "twilight" region); bit13 (0=no glint; 1=glint); bit14 (0=no snow/ice; 1=snow/ice); bits15-16 (00=clear; 01=probably clear; 10=cloudy; 11=clear-sky mask undefined) | N/A | short | N/A | -32768 to 32767 | 1 |
| ni | x coordinate of projection | radians | float | N/A | -0.15366402 to 0.15366402 | 1 |
| nj | y coordinate of projection | radians | float | N/A | -0.15366402 to 0.15366402 | 1 |
| quality_level | SST quality levels: 5 corresponds to "clear-sky" pixels and is recommended for operational applications and validation. | N/A | byte | -128 | 0 to 5 | 1 |
| satellite_zenith_angle | satellite zenith angle | degrees | byte | -128 | -90 to 90 | 1 |
| sea_ice_fraction | Fractional sea ice cover from reference SST | 1 | byte | -128 | 0 to 100 | 0.01 |
| sea_surface_temperature | SST obtained by collation algorithm | kelvin | short | -32768 | -32767 to 32767 | 0.01 |
| sses_bias | Bias is derived against Piecewise Regression SST produced by local regressions with buoys. Subtracting sses_bias from sea_surface_temperature producess more accurate SST at the depth of buoys Further information at (Petrenko et al., JTECH, 2016; doi:10.1175/JTECH-D-15-0166.1) | kelvin | byte | -128 | -127 to 127 | 0.016 |
| sses_standard_deviation | Standard deviation of sea_surface_temperature from SST measured by drifting buoys. Further information at (Petrenko et al., JTECH, 2016; doi:10.1175/JTECH-D-15-0166.1) | kelvin | byte | -128 | -127 to 127 | 0.01 |
| sst_dtime | time plus sst_dtime gives seconds since 1981-01-01 00:00:00 UTC | seconds | short | -32768 | -32767 to 32767 | 0.25 |
| time | Seconds since 1981-01-01 00:00:00 | seconds since 1981-01-01 00:00:00 | int | N/A | N/A | 1 |
| wind_speed | Typically represents surface winds (10 meters above the sea surface) | m s-1 | byte | -128 | -127 to 127 | 0.15 |