******************************************************************** * * * BU/UCL/UWS Jornada Albedo Data * * * * README for data files * * * * Andrew Hyman 12th August 1998 * * * ******************************************************************** ORNL DAAC Data Processing Notes October 14, 2002 The 11 (eleven) original small albedo data files were combined into one .csv file with new variables for date, transect, and applicable corrections. Data file format documentation has been modified. Hemispherical and classified photographs have been zipped and are available as data files. Three pairs of color/classified photographs are included in .pdf format as companion files. Contact DAAC User Services with questions. Original postscript files of the MA Thesis were converted to Acrobat .pdf format for user convenience. Postscript files have been compressed and are available on the ORNL DAAC ftp site. ----------------------------------------------- 1. Introduction and Team Members ------------------------------------------------ This README file details data collected by Boston University in collaboration with University College London and University Wales, Swansea during the PROVE campaign at Jornada, NM May 20-30 1997 as part of a coordinated MODLAND validation prototyping exercise. Funding was provided by NASA grant NAS5-31369 (PI: Prof Alan Strahler). Full background information on data processing and results of our analyses are available in the provided Master's Thesis by Andrew Hyman (1998). This work was subsequently published in Remote Sensing of Environment in 2000 (see references below for further details). Lead Investigators: Andrew Hyman e-mail: ahh24@cam.ac.uk Department of Geography, University of Cambridge, UK Wolfgang Lucht e-mail: wlucht@crsa.bu.edu Alan Strahler e-mail: alan@bu.edu Boston University In collaboration with: Jan-Peter Muller University College London Mike Barnsley Paul Hobson University of Wales, Swansea Please direct any questions you may have regarding the data to either: Dr Wolfgang Lucht, Center for Remote Sensing, Boston University, 725 Commonwealth Avenue, Boston, MA 02215. Tel: +1 (617) 353 8033 Fax: +1 (617) 353 3200 e-mail: wlucht@crsa.bu.edu or: Andrew Hyman, Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, United Kingdom. e-mail: ahh24@cam.ac.uk ----------------------------------- 2. Description of data files ----------------------------------- Total shortwave and NIR broadband albedo data Broadband albedo data was collected using Kipp and Zonen CM14 albedometers. The data file contains albedo values collected along 5 transects which are identified by date and name. The albedo values in these files are averages of 5 (or occasionally more) measurements taken at each point on the transects. Missing values are coded as –999. The file format is .csv and will open as described in Excel. Variables (columns) Description Units/Format Sensor Date_collected Date measurement taken yyyy/mm/dd Not applicable Transect Measurement transect starting at tower and extending in named direction None Not applicable Site number Measurement location along transects. 1 references the site closet to the tower and 11 the site farthest from the tower. For the grassland transects, site 1 is located at the end by the road / fence. Integer Not applicable SZA corrected SZA corrected files provide values with corrections for solar zenith angle effects Yes/No Not applicable Soil moisture corrected Moisture corrected files provide values corrected for soil moisture effects Yes/No Not applicable Time_local Mountain Standard Time (6 hour offset) hh:mm Not applicable Time_GMT Greenwich Mean Time hh:mm Not applicable Albedo_SW SW_albedo is the total broadband albedo 305-2800nm % Kipp and Zonen CM14 albedometers Albedo_NIR NIR_albedo is the NIR broadband albedo 695-2800nm % Kipp and Zonen CM14 albedometers Solar_azimuth Solar azimuth angle Degrees Calculated? Solar_zenith Solar zenith angle Degrees Calculated? Latitude Latitude provided in decimal degrees from differentially corrected GPS measurements with the WGS84 datum. Decimal Degrees Trimble GeoExplorer II Longitude Longitude provided in decimal degrees from differentially corrected GPS measurements with the WGS84 datum. Decimal Degrees Trimble GeoExplorer II Altitude Height is in metres above MSL. m Trimble GeoExplorer II Photoid photoid is a file name identifier for associated hemispherical photographs and classified images. None Not applicable Original data file name Original data file name from Hyman and Lucht before consolidation and addition of date, location, and correction variables. None Not applicable Latitude and longitude, provided in decimal degrees are from differentially corrected GPS measurements with the WGS84 datum. Data was collected using a Trimble GeoExplorer II. 120 samples were taken at each location point with a 5 second sampling rate ensuring that a minimum of 4 satellites were in view. Differential correction was performed using coincident measurements taken using data from the permanent Trimble GPS installation at New Mexico State University. Original data files combined into one file by ORNL DAAC. These files have been zipped into a file named albedo_original_files.zip and are available on the ORNL DAAC ftp site. 22ndMay1997_north_sza_corrected.dat 23rdMay1997_east_sza_mois_corrected.dat 23rdMay1997_north_sza_corrected.dat 23rdMay1997_south_sza_mois_corrected.dat 25thMay1997_longeast_sza_corrected.dat 25thMay1997_middle_longeast_sza_corrected.dat 26thMay1997_north_sza_corrected.dat 26thMay1997_west_sza_corrected.dat 27thMay1997_grassland1_sza_corrected.dat 27thMay1997_grassland2_sza_corrected.dat 27thMay1997_grassland3_sza_corrected.dat Original Notes: i) sza files provide values with corrections for solar zenith angle effects for the north, west, longeast and grassland transects ii) sza_mois files provides values for the south and east transect measurements corrected for both solar zenith angle and soil moisture effects iii) grassland1, grassland2 and grassland3 refer to three transects measured at different times on the 27th May iv) Decimalised time is calculated using: (($2!=0)&&($1!="#")){ time=$2; hours=int(time/10000); time-=(hours*10000); minutes=int(time/100); seconds=time-(minutes*100); print (hours*3600 + minutes*60 + seconds) } Hemispherical photography b) Hemispherical photography was acquired for all sites for which albedo was measured. File names correspond to photoid field in albedo data file. Hemispherical and classified photographs have been zipped and are available as data files. Three pairs of color/classified photographs are included in .pdf format as companion files. Header information for hemispherical photography (*photo.bin) files is: Number of lines: 1024 Number of samples: 1536 Number of bands: 3 (BIP - Band Interleaved by Pixel) Bytes: 1 Byteorder: 3210 (as reported by IPW) Header information for classified image (*classified.bin) files is: Number of lines: 1024 Number of samples: 1536 Number of bands: 1 Bytes: 1 Byteorder: 3210 (as reported by IPW) The classified images contain five values: Digital Number Class 0 Unclassified 50 Soil 100 Grey / dormant vegetation 150 Dead / woody vegetation 200 Live vegetation Hyman MA Thesis c) Original postscript files of the MA Thesis were converted to Acrobat .pdf format, combined into one .pdf document, and it is a companion file for this data set for user convenience. Postscript files have been compressed and are available on the ORNL DAAC ftp site. Postscript files of the MA Thesis that provides a full report on the study are: File: Contents: jornada_albedo_prelim.ps Preliminary pages jornada_albedo_main.ps Main text jornada_albedo_sec1_figs.ps Section 1 figures jornada_albedo_sec2_figs.ps Section 2 figures jornada_albedo_sec3_figs.ps Section 3 figures jornada_albedo_sec4_figs.ps Section 4 figures jornada_albedo_sec5_figs.ps Section 5 figures jornada_albedo_sec6_figs.ps Section 6 figures jornada_albedo_references.ps References These are formatted for US Letter Size paper. ------------------------------------------------------ 3. Requested Acknowledgement / References for data use ------------------------------------------------------ Please note that use of this data should include the following reference: Hyman, A.H. 1998: Characterising the spatial variability of albedo in a semi-desert environment for the validation of satellite data. Master's Thesis, Boston University, unpublished. Citations should subsequently make reference to journal articles published in a special issue of Remote Sensing of Environment on Jornada in 2000. Barnsley, M.J., P.D. Hobson*, A.H. Hyman, W. Lucht, J-P. Muller and A.H. Strahler. 2000. Characterizing the Spatial Variability of Broadband Albedo in a Semidesert Environment for MODIS Validation. Remote Sensing of Environment, Volume 74, Issue 1.