Entry_ID: NSIDC-0094
Entry_Title: AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid Composites
Group: Data_Set_Citation
   Dataset_Creator: C. Fowler, J. Maslanik, T. Haran, T. Scambos, J. Key, and W. Emery.
   Dataset_Title: AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid Composites
   Dataset_Release_Date: 2002-01-01
   Dataset_Release_Place: Boulder, Colorado USA
   Dataset_Publisher: NSIDC: National Snow and Ice Data Center
   Online_Resource: http://nsidc.org/data/nsidc-0094.html
End_Group
Group: Personnel
   Role: Investigator
   First_Name: Chuck
   Last_Name: Fowler
   Group: Contact_Address
      Address: Colorado Center for Astrodynamics Research
      Address: University of Colorado
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309-0431
   End_Group
End_Group
Group: Personnel
   Role: Investigator
   First_Name: Jim
   Last_Name: Maslanik
   Email: nsidc@kryos.colorado.edu
   Phone: 1 303 492-6199 
   Fax: 1 303  492-2468 
   Group: Contact_Address
      Address: National Snow and Ice Data Center
      Address: CIRES, 449 UCB
      Address: University of Colorado
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309
   End_Group
End_Group
Group: Personnel
   Role: Investigator
   First_Name: Terry
   Last_Name: Haran
   Group: Contact_Address
      Address: National Snow and Ice Data Center
      Address: CIRES,  449 UCB
      Address: University of Colorado
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309-0449
   End_Group
End_Group
Group: Personnel
   Role: Investigator
   First_Name: Ted
   Last_Name: Scambos
   Email: scambos@nsidc.org
   Group: Contact_Address
      Address: University of Colorado
      Address: Cooperative Institute for Research in Environmental Science
      Address: National Snow and Ice Data Center
      Address: CIRES,  449 UCB
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309-0449
   End_Group
End_Group
Group: Personnel
   Role: Investigator
   First_Name: Jeffrey
   Last_Name: Key
   Group: Contact_Address
      Address: Space Science and Engineering Center
      Address: University of Wisconsin at Madison
      Address: 1225 W. Dayton St.
      City: Madison
      Province_or_State: WI
      Postal_Code: 53706
   End_Group
End_Group
Group: Personnel
   Role: Investigator
   First_Name: William
   Last_Name: Emery
   Group: Contact_Address
      Address: Colorado Center for Astrodynamics Research
      Address: University of Colorado
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309-0431
   End_Group
End_Group
Group: Personnel
   Role: Technical Contact
   First_Name: NSIDC
   Last_Name: User Services
   Email: nsidc@nsidc.org
   Phone: 1 303 492-6199 x
   Fax: 1 303  492-2468 x
   Group: Contact_Address
      Address: National Snow and Ice Data Center
      Address: CIRES, 449 UCB
      Address: University of Colorado
      City: Boulder
      Province_or_State: CO
      Postal_Code: 80309-0449
      Country: USA
   End_Group
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Atmosphere
   Term: Atmospheric Radiation
   Variable_Level_1: Albedo
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Atmosphere
   Term: Clouds
   Variable_Level_1: Cloud Amount/Frequency
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Cryosphere
   Term: Snow/Ice
   Variable_Level_1: Albedo
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Land Surface
   Term: Land Temperature
   Variable_Level_1: Land Surface Temperature
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Land Surface
   Term: Land Temperature
   Variable_Level_1: Skin Temperature
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Land Surface
   Term: Surface Radiative Properties
   Variable_Level_1: Albedo
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Land Surface
   Term: Surface Radiative Properties
   Variable_Level_1: Thermal Properties
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Spectral/Engineering
   Term: Infrared Wavelengths
   Variable_Level_1: Infrared Radiance
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Spectral/Engineering
   Term: Infrared Wavelengths
   Variable_Level_1: Thermal Infrared
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Spectral/Engineering
   Term: Platform Characteristics
   Variable_Level_1: Viewing Geometry
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Spectral/Engineering
   Term: Visible Wavelengths
   Variable_Level_1: Visible Radiance
End_Group
Group: Parameters
   Category: EARTH SCIENCE
   Topic: Terrestrial Hydrosphere
   Term: Snow/Ice
   Variable_Level_1: Albedo
End_Group
Keyword: Antarctic
Keyword: Arctic
Keyword: AVHRR
Keyword: Cryosphere
Keyword: DAAC
Keyword: EOSDIS
Keyword: NASA
Keyword: NOAA
Keyword: NSIDC
Keyword: Pathfinder
Keyword: Polar
Keyword: Radiance
Keyword: Remote Sensing
Keyword: Satellite
Sensor_Name: AVHRR > Advanced Very High Resolution Radiometer
Sensor_Name: RADIOMETERS
Source_Name: NOAA-11 > National Oceanic & Atmospheric Administration-11
Source_Name: NOAA-14 > National Oceanic & Atmospheric Administration-14
Source_Name: NOAA-7 > National Oceanic & Atmospheric Administration-7
Source_Name: NOAA-9 > National Oceanic & Atmospheric Administration-9
Group: Temporal_Coverage
   Start_Date: 1981-07-24
   Stop_Date: 2000-12-31
End_Group
Data_Set_Progress: in work
Group: Spatial_Coverage
   Southernmost_Latitude: -90
   Northernmost_Latitude: -53.2
   Westernmost_Longitude: -180
   Easternmost_Longitude: 180
End_Group
Group: Spatial_Coverage
   Southernmost_Latitude: 48.4
   Northernmost_Latitude: 90
   Westernmost_Longitude: -180
   Easternmost_Longitude: 180
End_Group
Group: Location
   Location_Category: CONTINENT
   Location_Type: ANTARCTICA
End_Group
Group: Location
   Location_Category: GEOGRAPHIC REGION
   Location_Type: ARCTIC
End_Group
Group: Location
   Location_Category: GEOGRAPHIC REGION
   Location_Type: POLAR
End_Group
Group: Data_Resolution
   Temporal_Resolution: 12:00:00
End_Group
Project: NOAA/NASA PATHFINDER > NOAA/NASA Pathfinder Program
Group: Quality

   Channel data are accurate to within approximately +/- 0.2 percent based on 
   sensor noise level of 0.4 data number (DN). Temperatures are accurate to 
   within approximately 2 degrees Kelvin. Relative albedos in adjacent grid cells 
   are accurate to within approximately 5 percent. However, absolute albedo 
   values are approximate.  Accuracies for the products are difficult to 
   determine, given the limited nature of existing case studies.  Also, 
   conditions vary substantially across the large product domains and over time.  
   Plans are being developed to further define product accuracies for 
   snow-covered areas, sea ice, and ice sheets.  Based on studies to date, 
   accuracies in general are approximately +/- 2 degrees Kelvin for AVHRR-derived 
   skin temperatures and +/- 0.05 degrees for surface albedo. Much of this error 
   is likely due to uncertainties in the performance of the cloud detection 
   methods. For clear sky conditions, accuracies for albedo and temperature 
   products are expected to be in the range noted in the Barrow test, with 
   temperatures accurate to +/- 0.5 degrees Celsius.  Data and related 
   information will be updated as appropriate. Additional comparisons with 
   in-situ measurements of albedo and temperature are planned.  See also Maslanik 
   et al. (2000) for other accuracy discussions relative to SHEBA data.

End_Group
Data_Set_Language: English
Group: Data_Center
   Data_Center_Name: NASA DAAC > NASA DAAC at the National Snow and Ice Data Center
   Data_Center_URL: http://nsidc.org/daac/index.html
   Group: Personnel
      Role: Data Center Contact
      First_Name: NSIDC
      Last_Name: User Services
      Email: nsidc@nsidc.org
      Phone: 1 303 492-6199 
      Fax: 1 303  492-2468 
      Group: Contact_Address
         Address: National Snow and Ice Data Center
         Address: CIRES, 449 UCB
         Address: University of Colorado
         City: Boulder
         Province_or_State: CO
         Postal_Code: 80309-0449
         Country: USA
      End_Group
   End_Group
End_Group
Group: Data_Center
   Data_Center_Name: NSIDC > National Snow and Ice Data Center
   Data_Center_URL: http://nsidc.org
   Group: Personnel
      Role: Data Center Contact
      First_Name: NSIDC
      Last_Name: User Services
      Email: nsidc@nsidc.org
      Phone: 1 303 492-6199 
      Fax: 1 303  492-2468 
      Group: Contact_Address
         Address: National Snow and Ice Data Center
         Address: CIRES, 449 UCB
         Address: University of Colorado
         City: Boulder
         Province_or_State: CO
         Postal_Code: 80309-0449
         Country: USA
      End_Group
   End_Group
End_Group
Group: Distribution
   Distribution_Media: FTP
   Distribution_Size: 127.3 KB
   Distribution_Format: Binary
End_Group
Group: Distribution
   Distribution_Media: FTP
   Distribution_Size: 225.2 KB
   Distribution_Format: Binary
End_Group
Group: Reference

   Key, J. 1999. The cloud and surface parameter retrieval (CASPR) system for 
   polar AVHRR. Cooperative Institute for Meteorological Satellite Studies, 
   University of Wisconsin, Madison.

   Key, J., J. Collins, C. Fowler, and R.S. Stone. 1997. High-latitude surface 
   temperature estimates from thermal satellite data. Remote Sensing of the 
   Environment 61:302-309.

   Kidwell, K.D. 1995. NOAA Polar Orbiter Data User's Guide, U.S. Dept. of 
   Commerce, National Oceanic and Atmospheric Administration, NESDIS.

   Maslanik, J., C. Fowler, J. Key, T. Scambos, T. Hutchinson, and W. Emery, 
   1998. AVHRR-based Polar Pathfinder products for modeling applications. Annals 
   of Glaciology 25:388-392.

   Rao, C.R.N. and J. Chen. 1999. Revised post-launch calibration of channels 1 
   and 2 of the Advanced Very High Resolution Radiometer on board the NOAA-14 
   spacecraft. http://noaasis.noaa.gov/NOAASIS/ml/aboutn14vis.html.

   Schweiger, A., C. Fowler, J. Key, J. Maslanik, J. Francis, R. Armstrong, M.J. 
   Brodzik, T. Scambos, T. Haran, M. Ortmeyer, S. Khalsa, D. Rothrock, and R. 
   Weaver. 1999. P-Cube: A multisensor data set for polar climate research. 
   Proceedings on the 5th Conference on Polar Meteorology and Oceanography, 
   American Meteorological Society, Dallas, TX, 15-20 Jan., 136-141.

End_Group
Group: Summary

   This data set is no longer available because of errors 
   in the data. See the Error 
   Sources section of the data set documentation for details. If you have 
   further questions, please contact NSIDC User Services by e-mail at nsidc@nsidc.org or telephone at +1 
   303.492.6199.

   The AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid Composites are a 
   collection of products for both poles, consisting of twice-daily gridded and 
   calibrated satellite channel data and derived parameters. Data include five 
   Advanced Very High Resolution Radiometer (AVHRR) channels, clear sky surface 
   broadband albedo and skin temperature, average albedo and temperature, valid 
   fraction file, solar zenith angle, satellite elevation angle, sun-satellite 
   relative azimuth angle, surface type mask, cloud mask, cloud fraction files, 
   and Universal Coordinated Time (UTC) of acquisition. The 25 km data are 
   derived from the AVHRR Polar Pathfinder Twice-Daily 5 km EASE-Grid Composites, 
   and extend poleward from 48.4 degrees north and 53.2 degrees south latitudes, 
   spanning July 1981 through December 2000. Data are in 1-byte and 2-byte 
   integer grid format and are available by FTP. 

   Note: NSIDC reccommends the use of the Extended AVHRR Polar Pathfinder (APP-x) 
   Product instead of our AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid 
   Composites. The APP-x 25 km product has albedo and temperature calculations 
   for all sky conditions. Cloud properties are modeled to estimate the albedo 
   and temperature under the clouds. An improved cloud detection algorithm is 
   also used in the APP-x product.

End_Group
Group: Related_URL
   Group: URL_Content_Type
      Type: VIEW PROJECT HOME PAGE
   End_Group
   URL: http://nsidc.org/data/avhrr/index.html
   Description: AVHRR Data at NSIDC
End_Group
Group: Related_URL
   Group: URL_Content_Type
      Type: VIEW PROJECT HOME PAGE
   End_Group
   URL: http://nsidc.org/daac/pathfinder/index.html
   Description: Polar Pathfinders at NSIDC
End_Group
Group: Related_URL
   Group: URL_Content_Type
      Type: VIEW RELATED INFORMATION
   End_Group
   URL: http://nsidc.org/data/ease/
   Description: All About EASE-Grid
End_Group
IDN_Node: USA/NASA
Metadata_Name: CEOS IDN DIF
Metadata_Version: 9.7
DIF_Creation_Date: 2002-01-01
Last_DIF_Revision_Date: 2013-11-26
Group: DIF_Revision_History

   Removed "replacement data are expected by the end of 2012" from summary per 
   USO request.

End_Group