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|accessions_id:||0072888 | archive|
|Title:||4 km NODC/RSMAS AVHRR Pathfinder v5 Seasonal and Annual Day-Night Sea Surface Temperature Climatologies for 1982-2009 for the Gulf of Mexico (NODC Accession 0072888)|
|Abstract:||This accession contains a set of sea surface temperature climatologies for the Gulf of Mexico (GOM), derived from the AVHRR Pathfinder Version 5 sea surface temperature data set (http://pathfinder.nodc.noaa.gov). These GOM climatologies were produced from 5-day cloud-screened day-night averages of Pathfinder SST data from 1982-2009, which are archived at the National Oceanographic Data Center under separate accession numbers. In addition to sea surface temperature, the climatologies also include minimum, maximum, standard deviation, and number of observations.|
The climatologies are available as 32-bit Tagged Image File Format (.TIFF) data files for 1982-2009 and include seasonal and yearly time periods. The climatologies are also included as Arc Grid (.mxd) and .PNG layers with associated legends for user convenience and were assigned projection GCS_WGS_1984. An additional subdirectory contains the annual mean, season 1 (Jan-Mar) mean, season 2 (Apr -June) mean, season 3 (Jul - Sept) mean, and season 4 (Oct-Dec) mean as color-classified .PNG images with a matching shape file that we developed for use in online visualizations.
A separate GOM land mask which will also display inland water bodies has been included with this accession. The land mask was developed from the Global Self-consistent, Hierarchical, High-resolution Shoreline Database v2.2.0 product (Wessel and Smith, 2011). The user should note that although quality flags were assigned consistently for all water pixels, SSTs for inland water bodies (lakes and rivers) should be used with caution, as their accuracy has not been documented and there are numerous complexities involved with determining surface temperatures in inland regions.
|Seanames:||Coastal Waters of Florida, Coastal Waters of Gulf of Mexico, Florida Keys National Marine Sanctuary, Flower Garden Banks National Marine Sanctuary, Gulf of Mexico, North American Coastline-South, North Atlantic Ocean, Sarasota Bay, St. Andrew Bay - Florida, Straits of Florida|
|Observation types:||GIS product, satellite data|
|Instrument types:||AVHRR > Advanced Very High Resolution Radiometer, AVHRR-GAC|
|Datatypes:||SEA SURFACE TEMPERATURE|
|Platforms:||NOAA-11 SATELLITE, NOAA-14 SATELLITE, NOAA-16 SATELLITE, NOAA-17 SATELLITE, NOAA-18 SATELLITE, NOAA-7 SATELLITE, NOAA-9 SATELLITE|
|Number of observations:|
|Supplementary information:||The 4 km-resolution 5-day time series used to create these seasonal climatologies is computed from 1982-2009 using the Version 5.0 Pathfinder algorithm, an improved version of the previously most successful of the many methods used to derive SST from AVHRR observations (see Barton (1995) for a review of earlier techniques), the University of Miami Pathfinder version v4.2 SST algorithm (described fully in Kilpatrick et al., 2001). The v4.2 algorithm offered marked improvement over operational retrieval algorithms such as MCSST and was applied to AVHRR data to maximize accuracy and to minimize artificial fluctuations arising from the sequence of AVHRR instruments flown on NOAA's polar-orbiting satellites during the past 2 decades. The 9 km v4.2 Pathfinder SSTs have already been shown to be the highest quality product currently available for the construction of global climatologies (Casey and Cornillon, 1999) and longer-term SST trend determination (Casey and Cornillon, 2001), and have been demonstrated to be accurate within about 0.3 degrees C under optimal conditions (Kearns et al., 2000). Relative to the older 9 km v4.2 Pathfinder data, the new, ~ 4 km resolution Pathfinder Version 5.0 global SSTs increase detail by a factor of four simply by virtue of the increased resolution. The increase in detail over widely used but relatively coarse SST datasets such as Optimally Interpolated SST Version 2 (OISSTv2; Reynolds et al., 2002) and the Hadley Centre's Global Sea Ice and SST (HadISST1; Rayner et al., 2003) is far greater. |
In addition to the increased resolution, significant improvements have been made in the Version 5.0 which enhance the usefulness of the SST fields. Currently, these enhancements include the use of sea ice in the quality level determination scheme, inclusion of many inland water bodies, and the use of a greatly improved land mask. The greatest improvements are seen in coastal zones, marginal seas, and boundary current regions where SST gradients are often large and their impact on operational or research products is greatest. Separate SST products for daytime and nighttime AVHRR retrievals are made to better understand the differences in skin and bulk temperatures, since mean differences between AVHRR-measured skin temperatures and bulk temperatures of 0.1 to 0.2 degrees C (Schluessel et al., 1990) and locally varying differences of up to 1.8 degrees C (Minnett et al., 2000) have been observed.
The following is information to be used when reading the DAY-NIGHT geotiffs generated from the seasonal climatology data files:
Version: 1 Key_Revision: 1.0 Tagged_Information: ModelTiepointTag (2,3):0 0 0-180 90 0
ModelPixelScaleTag (1,3):0.0439453 0.0439453 0 End_Of_Tags.
Keyed_Information: GTModelTypeGeoKey (Short,1): ModelTypeGeographic
GTRasterTypeGeoKey (Short,1): RasterPixelIsArea GTCitationGeoKey (Ascii,17): 'LONG/LAT E005' GeographicTypeGeoKey
(Short,1): GCS_WGS_84 GeogAngularUnitsGeoKey (Short,1): Angular_Degree
ProjLinearUnitsGeoKey (Short,1): Linear_Meter End_Of_Keys.
End_Of_Geotiff. GCS: 4326/WGS 84 Datum: 6326/World Geodetic System
1984 Ellipsoid: 7030/WGS 84 (6378137.00,6356752.31) Prime Meridian: 8901/Greenwich (0.000000/ 0d 0' 0.00""E) Projection Linear Units:
9001/metre (1.000000m) Corner Coordinates:Upper Left (180d 0' 0.00"W, 90d 0' 0.00"N) Lower Left (180d 0' 0.00"W, 90d 0' 0.00"S) Upper Right
(180d 0' 0.00"E, 90d 0' 0.00"N) Lower Right (180d 0' 0.00"E, 90d 0' 0.00"S) Center ( 0d 0' 0.00"E, 0d 0' 0.00"N)
Note - the Geotiff data files for this accession are not colormapped; users may apply a colormap to these files as desired from within a GIS, Matlab, or orther software. The included .jpg and .png browse graphics provide representative views in color.
Additional processes required for SST climatologies: 1.The individual 5-day day-night cloudscreened files generated as part of the Version 5 Pathfinder Project for 1982-2009 were averaged into 3-month periods, or "seasons," to create a set of initial climatologies. For example, Season 1 of 1982, Season 1 of 1983, ...., Season 1 of 2009 were averaged to create a climatology for Season 1. In addition to the pre-screening of any data with a quality flag of less than 4, data with pixel values less than 16 were masked as NoData. This is because a pixel value translates to -1.8 degrees C, which is the coldest sea surface temperature possible. 2. Then, the temperature value was converted into degrees Celsius (Using the function New value = original value * 0.075 -3.0). 3. The time series maximum, minimum, average, number of observations and standard deviation were used for the final climatology data. 4. The final climatology maximum/minimum/average SST was the average of the time series maximum/minimum/average SST; the final climatology standard deviation was the standard deviation based on the seasonal average time series data; the final climatology number of observations was the total number of observations for all the seasonal time series data. Similar procedures were used for the annual climatology products.
These climatologies were developed from data in the following NODC accessions - NODC Accession numbers 001763, 001764, 001765, 001766, 001767, 001768, 001769, 001770, 001771, 001772, 001773, 001774, 001775, 001776, 001777, 001778, 001779, 0043733, 0043739, 0043745, 0043750, and 0043756.
Color classified images were developed for use online. For the color classified .PNG images, 1) a land mask was applied, 2) a an ArcGIS filtering and smoothing filter was utilized, and 3) the classification was done with a 0.5 degree interval starting from 16 to 32 celsius.
Included land mask developed from GSHHS v2.2.0, July 2011. Citation - Wessel, P., and W. H. F. Smith, A Global Self-consistent, Hierarchical, High-resolution Shoreline Database, J. Geophys. Res., 101, B4, pp. 8741-8743, 1996.
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