Entry_ID: NSIDC-0066
Entry_Title: AVHRR Polar Pathfinder Twice-Daily 5 km EASE-Grid Composites
Group: Data_Set_Citation
   Dataset_Creator: W. Emery, C. Fowler, T. Haran, J. Key, J. Maslanik, T. Scambos
   Dataset_Title: AVHRR Polar Pathfinder Twice-Daily 5 km EASE-Grid Composites
   Dataset_Release_Date: 2000-09-01
   Dataset_Release_Place: Boulder, Colorado USA
   Dataset_Publisher: NSIDC: National Snow and Ice Data Center
   Version: 3
   Online_Resource: http://nsidc.org/data/nsidc-0066.html
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: 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: 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: 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: 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: 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: 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: Brightness Temperature
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-16 > National Oceanic & Atmospheric Administration-16
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: 2005-06-30
End_Group
Data_Set_Progress: complete
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: ESIP > Earth Science Information Partners Program
Project: NOAA/NASA PATHFINDER > NOAA/NASA Pathfinder Program
Group: Quality

   Product validation is a continuing process that takes advantage of comparative 
   data as they become available. Comparisons were made between AVHRR Polar 
   Pathfinder clear sky skin temperatures and surface-based measurements obtained 
   at the South Pole over a seven-day period in 1995. These field data were 
   collected by Robert Stone of the Cooperative Institute for Research in 
   Environmental Sciences (CIRES) using a sled-mounted KT-19 pyrometer. Excluding 
   observations when cloud cover was present, the agreement was generally within 
   0.5 kelvin. For data averaged over a four-hour period, temperatures were 
   within 0.1 kelvin. A mean of -38.15 degrees Celsius for the AVHRR Polar 
   Pathfinder observations, versus a mean of -38.25 degrees Celsius for the field 
   data. Evaluations were also performed for the AVHRR Polar Pathfinder 
   retrievals of surface albedo over the Greenland Ice Sheet through comparisons 
   with albedo measured at 14 Automatic Weather Stations (AWS) around the 
   Greenland Ice Sheet from January 1997 to August 1998. Results show that 
   AVHRR-derived surface albedo values are, on average, 10 percent less than 
   those measured by the AWS stations. However, station measurements tend to be 
   positively biased by about four percent, and the differences in absolute 
   albedo may be less, about six percent. In regions of Greenland where the 
   albedo variability is small, such as the dry snow facies, the AVHRR albedo 
   uncertainty exceeds the natural variability. Stroeve concluded that while 
   further work is needed to improve the absolute accuracy of the AVHRR-derived 
   surface albedo, the data provide temporally and spatially consistent estimates 
   of the Greenland Ice Sheet albedo (Stroeve et al. 2001) and (Stroeve 2002).

   Analyses of the AVHRR Polar Pathfinder data, compared with data from the 
   Surface Heat Budget of the Arctic Ocean (SHEBA) project, are in progress. See 
   (Maslanik et al. 2000) for preliminary results. The cloud masking process was 
   assessed and refined throughout the duration of the project to optimize the 
   algorithm for the entire areas of coverage. Comparisons of areally-averaged 
   cloud fractions from the AVHRR Polar Pathfinder Twice-daily 5 km EASE-Grid 
   Composites with field observations at the SHEBA field site show that the AVHRR 
   data were within nine percent of the cloud lidar/radar observations averaged 
   from April to July 1998 with Pathfinder data underestimating cloud fraction 
   relative to the field measurements. Differences in monthly means for this 
   period ranged from 2 percent in June to 21 percent in July. Comparison of 
   all-sky skin temperature and albedo values derived from the AVHRR Polar 
   Pathfinder Twice-daily 5 km EASE-Grid Composites with SHEBA observations is 
   described in (Maslanik et al. 2000).

   Other validation studies of surface temperature and albedo retrieval 
   procedures included surface observations from a NOAA research site near 
   Barrow, Alaska, 71.32 degrees north latitude, 156.61 degrees west longitude. 
   Daily AVHRR data from a preliminary Pathfinder data set from mid-1992 to 
   mid-1993 were used for this validation (Meier et al. 1997). Surface 
   temperature estimates agreed with observations, with a correlation coefficient 
   of 0.98, a bias of -0.97, and a RMSE of 4.70. For surface albedo, the bias 
   (mean error) in the estimates was near zero, r=0.81, bias=0.00, RMSE=0.17, but 
   the individual observations exhibited significant variability, attributed to 
   surface inhomogeneity and retrieval scheme sensitivity to changes in 
   atmospheric aerosol and water vapor amounts. Accuracies of 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 kelvin for AVHRR-derived clear sky 
   skin temperatures and ± 0.06 kelvin for 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 Greenland Barrow case studies.

   Data and related information will be updated as appropriate.

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: 3.26 MB
   Distribution_Format: Binary
End_Group
Group: Distribution
   Distribution_Media: FTP
   Distribution_Size: 6.52 MB
   Distribution_Format: Binary
End_Group
Group: Reference

   Cracknell, A. P. 1997. The Advanced Very High Resolution Radiometer. London: 
   Taylor & Francis.

   Csiszar, I. and G. Gutman. 1999. Mapping Global Land Surface Albedo from NOAA 
   AVHRR. Journal of Geophysical Research 104(D6):6215-6228. Diner, D. J., J. V. 
   Martonchik, C. Borel, S. A. W. Gerstl, H. R. Gordon, Y. Knyazikhin, R. Myneni, 
   B. Pinty, M. M. Verstraete. 1999. MISR Level 2 Surface Retrieval Algorithm 
   Theoretical Basis. Jet Propulsion Laboratory.

   Goodison, B. E. 1989. Determination of Areal Snow Water Equivalent on the 
   Canadian Prairies Using Passive Microwave Satellite Data. IGARSS '89 
   Proceedings 3:1243-1246. Goodrum, Geoffrey, Katherine B. Kidwell, Wayne 
   Winston. 2000. NOAA KLM User's Guide with NOAA-N, -N' Supplement. National 
   Oceanic and Atmospheric Administration.

   Gustafson, G. B. et al. 1994. Support of Environmental Requirements for Cloud 
   Analysis and Archive (SERCAA), Phillips Laboratory, Hanscom Air Force Base, 
   Scientific Report No. 2, PL-TR-94-2114, 100 pp.

   Hapke, B. 1993. Theory of Reflectance and Emittance Spectroscopy. Cambridge: 
   Cambridge University Press.

   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. and A. J. Schweiger. 1998. Tools for Atmospheric Radiative Transfer: 
   Streamer and FluxNet. Computers and Geosciences 24(5):443-451.

   Key, J., J. Collins, Chuck 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. A., J. Key, Chuck Fowler, T. Nguyen. 2000. AVHRR-derived Regional 
   Cloud and Surface Conditions During SHEBA and FIRE-ACE. Journal of Geophysical 
   Research, in press.

   Maslanik, J., Chuck Fowler, J. Key, Ted Scambos, T. Hutchinson, and W. Emery. 
   1998. AVHRR-based Polar Pathfinder Products for Modeling Applications. Annals 
   of Glaciology 25:388-392.

   Meier, W. N., J. A. Maslanik, J. R. Key, and Chuck Fowler. 1997. 
   Multiparameter AVHRR-derived Products for Arctic Climate Studies. Earth 
   Interactions 1.

   Rao, C. R. N. 1993. Nonlinearity Corrections for the Thermal Infrared Channels 
   of the AVHRR: Assessment and Recommendations. NOAA Technical Report, NESDIS 
   69:31.

   Rao, C. R. N. and J. Chen. 1994. Post-launch Calibration of the Visible and 
   Near-infrared Channels of the Advanced Very High Resolution Radiometer on 
   NOAA-7, -9, and -11 Spacecraft. NOAA Technical Report NESDIS 78:22 .

   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. Rosborough, 
   G. W., D. G. Baldwin, and W. J. Emery. 1994. Precise AVHRR Image Navigation. 
   IEEE Transactions in Geosciences and Remote Sensing 32(3):644-657. Saunders, 
   R. W. and K. T. Kriebel. 1988. An Improved Method for Detecting Clear Sky and 
   Cloudy Radiances from AVHRR Data. International Journal of Remote Sensing 
   9(1):123-150.

   Schweiger, A., Chuck Fowler, J. Key, J. Maslanik, J. Francis, Richard 
   Armstrong, Mary Joe Brodzik, Ted Scambos, Terry Haran, M. Ortmeyer, S. Khalsa, 
   D. Rothrock, and Ron 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.

   Schweiger, A. J. and J. R. Key. 1992. Arctic Cloudiness: Comparison of 
   ISCCP-C2 and Nimbus-7 Satellite-derived Cloud Products with a Surface-based 
   Cloud Climatology. Journal of Climate 5(12):1514-1527.

   Stowe, L.L., E.P. McClain, R. Carey, P. Pellegrino, and G.G. Gutman. 1991. 
   Global Distribution of Cloud Cover Derived from NOAA/AVHRR Operational 
   Satellite Data. Advances in Space Research 11(3): 51- 54.

   Stroeve, Julienne C., J. E. Box, Chuck Fowler, Terry Haran, and Jeffrey Key. 
   March 2001. Intercomparison Between in Situ and AVHRR Polar Pathfinder-derived 
   Surface Albedo Over Greenland. Remote Sensing of the Environment 75(3):360-374.

   Stroeve, Julienne C. 2002. Assessment of Greenland Albedo Variability from the 
   AVHRR Polar Pathfinder Data Set. Journal of Geophysical Research 
   106(D24):33,989-34,005.

   Suttles, J. T., R. N. Green, P. Minnis, G .L. Smith, W. F. Staylor, B. A. 
   Wielicki, I. J. Walker, D. F. Young, V. R. Taylor, and L. L. Stowe. 1988. 
   Angular Radiation Models for Earth-Atmosphere System. Shortwave Radiation, 
   NASA Reference Publication 1(1184):144.

   Walton, C. C., J. T. Sullivan, C. R. N. Rao, and M. P. Weinreb. 1998. 
   Corrections for Detector Nonlinearities and Calibration Inconsistencies of the 
   Infrared Channels of the Advanced Very High Resolution Radiometer. Journal of 
   Geophysical Research 103(C2):3323-3337.

   Yamanouchi, T., K. Suziki, and S. Kawaguchi. 1987. Detection of Clouds in 
   Antarctica from Infrared Multispectral Data of AVHRR. Journal of 
   Meteorological Society Japan 65(6):949-961.

End_Group
Group: Summary

   This data set is no longer available due to 
   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 or telephone at +1 303.492.6199.

   The Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder 
   Twice-Daily 5 km EASE-Grid Composites are a collection of products for both 
   poles, consisting of twice-daily calibrated and gridded satellite channel data 
   and derived parameters. Data include five AVHRR channels, clear sky surface 
   broadband albedo and skin temperature, solar zenith angle, satellite elevation 
   angle, sun-satellite relative azimuth angle, surface type mask, cloud mask, 
   and Universal Coordinated Time (UTC) of acquisition. AVHRR Polar Pathfinder 
   data extend pole ward from 48.4 degrees north and 53.2 degrees south 
   latitudes, from 24 July 1981 through 30 June 2005. Data are in 1-byte and 
   2-byte integer grid format and are available by FTP. 

   Note: Due to a problem with the NOAA-16 scan motor, all the channel data is 
   shifted sporadically between 2001 and 2005, causing the channels to contain 
   data from another channel; thus, the derived parameters also contain errors 
   during this time-period. See Table 12 in the Error Sources section of this 
   document for specific dates.

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: NOAA/NASA Pathfinder Program
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
Group: Related_URL
   Group: URL_Content_Type
      Type: VIEW RELATED INFORMATION
   End_Group
   URL: http://nsidc.org/data/ease/index.html
   Description: All About EASE-Grid
End_Group
IDN_Node: USA/NASA
Metadata_Name: CEOS IDN DIF
Metadata_Version: 9.7
DIF_Creation_Date: 2000-09-01
Last_DIF_Revision_Date: 2014-02-03
DIF_Revision_History: Removed reference to future data availability from summary.