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OAS accession Detail for 0075098
| << previous | |revision: 13 |
| accessions_id: | 0075098 | archive |
|---|---|
| Title: | AVHRR Pathfinder version 5.0 and 5.1 4km global sea surface temperature (SST) monthly harmonic climatologies for 1982-2008 (NCEI Accession 0075098) |
| Abstract: | This dataset contains a global, 4km monthly sea surface temperature climatology derived from harmonic analysis of the AVHRR Pathfinder Version 5.0 and 5.1 sea surface temperature time series data for 1982-2008. The climatology is available as 12 separate files, each representing one month in a climatological year. The files are in netCDF-4 and fully comply with the GHRSST Data Specification 2.0 for Level 4 products. In addition to climatological sea surface temperature, each file contains standard deviation, sea ice concentration, sea ice concentration error, and land mask information. This dataset also includes a 'classic,' or mean, monthly sea surface temperature climatology derived from the same Pathfinder time series data. This climatology was used to gap-fill the harmonic climatology, and provided the standard deviation information. It is available as 12 separate files in Hierarchical Data Format Version 4 (HDF4). In some ice-dominated high-latitude areas, the harmonic climatology is poorly constrained due to uneven distribution throughout the year of the valid measurements. For example, at 82.6N, 48W off the coast of Greenland, temperatures estimated in the harmonic climatology reach over 35C. In these regions, the classic, averaged climatological values may be more reliable. Associated daily and 5-day harmonic climatologies are archived at NCEI under accessions 0071181 and 0071182, respectively. |
| Date received: | 20110815 |
| Start date: | 19820101 |
| End date: | 20081231 |
| Seanames: | World-Wide Distribution |
| West boundary: | -180 |
| East boundary: | 180 |
| North boundary: | 90 |
| South boundary: | -90 |
| Observation types: | derived products, satellite data |
| Instrument types: | AVHRR-2, AVHRR-3 |
| Datatypes: | SEA SURFACE TEMPERATURE |
| Submitter: | Casey, Dr. Kenneth S. |
| Submitting institution: | US DOC; NOAA; NESDIS; National Oceanographic Data Center |
| Collecting institutions: | University of Miami Rosenstiel School of Marine and Atmospheric Science, US DOC; NOAA; NESDIS; National Oceanographic Data Center |
| Contributing projects: | Pathfinder |
| Platforms: | NOAA-11 (3101), NOAA-14 (3277), NOAA-16 (33J9), NOAA-17 (33ZS), NOAA-18 (33WM), NOAA-7 (33V2), NOAA-9 (33OO) |
| Number of observations: | |
| Supplementary information: | The procedure used to generate this monthly harmonic climatology can be broken down into two primary components: 1. Harmonic analysis of time series data The harmonic climatology is created by fitting to a time series of SST data at each pixel a cosine function containing both annual and semi-annual components: SST = A * cos(2pi*t + B) + C * cos(4pi*t + D) + E The constants A and B correspond to the annual amplitude and annual phase, respectively. The constants C and D correspond to the semi-annual amplitude and phase. The constant E is the long term mean at that pixel. The input time series consists of pentad (5-day) averages of best-quality data (quality flag 7) only for 1982-2008. These data are archived by NODC in separate yearly accessions. To create a gap-free data set for analysis, median spatial fill routines are applied to each 5-day global SST average in the time series. Using a curve-fitting tool in Matlab (lsqcurvefit.m), the cosine function is fit to the SST time series and the five harmonic constants are calculated. Note: If fewer than 100 good observations are available for a given pixel, the amplitudes (A and C) are set to zero, phases (B and D) set to one, and the long term mean (E) is set to the mean at that pixel. 2. Application of harmonic parameters The five harmonic constants can then be plugged into the cosine function to solve for sea surface temperature at any temporal resolution. In this case, the constants are applied at a monthly resolution to calculate sea surface temperature for 12 months in a climatological year. For pixels missing SST values, where the harmonic analysis failed to converge to a solution, median spatial fill routines are applied. Any remaining pixels with missing values after median filling are filled using SST values from the classic climatology. File-naming convention for monthly harmonic climatology files: [0000][MMDD][HHMMSS]-NODC-L4_GHRSST-SSTskin-AVHRR_Pathfinder-PFV5.0_Monthly_Climatology_1982_2008_DayNightCombined-v02.0-fv[##.#].nc 0000 - representative year of analysis (climatological year) MMDD - representative month and day of analysis, e.g. 0630 for June 30 of the climatological year HHMMSS - representative time (6-digit hour, minute and second) of analysis. ##.# - file version, e.g. 01.0 |
| Availability date: | 20110819 |
| Metadata version: | 13 |
| Keydate: | 2011-08-18 14:44:28+00 |
| Editdate: | 2022-01-13 14:49:55+00 |