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ISLSCP II MODIS (Collection 4) Albedo, 2002
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Revision date: December 01, 2009

Summary:

The MODIS BRDF/Albedo Product (MOD43B) provides measures of clear sky surface albedo every 16 days. Both white-sky albedo (bihemispherical reflectance) and black-sky albedo (directional hemispherical reflectance) at local solar noon are provided for 7 spectral bands and 3 broadbands. Since black-sky albedo represents the direct beam contribution while white-sky represents the completely diffuse contribution, these measures can be linearly combined as a function of the fraction of diffuse skylight (itself a function of optical depth) to provide an actual or instantaneous albedo at local solar noon. 

This data set provides albedo data (white-sky albedo, black-sky albedo, and albedo quality information) for for the peroid January 2002 through December 2002 at spatial resolutions of 0.25, 0.5, and 1.0 degrees latitude by longitude in standard ESRI ArcInfo ASCII GRID format in nine *.zip files.

 

Additional Documentation

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. Selected data sets span even longer periods. A complete description of the data, their derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_modis_albedo_2002_doc.pdf

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

 

Data Citation:

Cite this data set as follows:

Strahler, A.H., C.L.B. Schaaf, and F. Gao. 2009. ISLSCP II MODIS (Collection 4) Albedo, 2002. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/958

 

Data Description:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the vegetation category--a collection of vegetation and albedo data sets.

Data Set Spatial Extent: Global gridded

Western most Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90N

Southernmost Latitude: -90S

Projection: Geographic

Data Set Spatial Resolution: one-degree, half-degree, and quarter-degree in both latitude and longitude

Data Set Temporal Extent: January 2002 through December 2002

Data Set Temporal Resolution: Synoptic months

 

Data File Format

All of the data files in each data set within the ISLSCP Initiative II data collection are in ESRI ASCII GRID format for ArcInfo. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The files at different spatial resolutions each contain the following numbers of columns and rows:
      1 degree: 360 columns by 180 rows
      1/2 degree: 720 columns by 360 rows
      1/4 degree: 1440 columns by 720 rows

Within the albedo files, values for each pixel are stored as a real number. Values for albedo range between 0 and 1.

Data Values:

All water bodies have a fixed value of -99.0000

Missing values over land are assigned the value of -88.0000

 

The data files fall into the following categories:

Black Sky Albedo (BSA) Surface black-sky albedo at local solar noon derived from MODIS multidate surface reflectances in bands 1-7 and 3 broadbands. Albedo is the fraction of incident solar radiation that a surface reflects -- in this case a direct beam solar illumination condition.
White Sky Albedo (WSA) White sky albedo under entirely diffuse solar illumination conditions for MODIS bands 1-7 and 3 broadbands
Albedo Quality Information (QA) Eight layers of Albedo QA associated with MODIS Albedo products.

* modis_albedo_1deg/

modis_bsa_1d_2002.zip

modis_qa_1d_2002.zip

modis_wsa_1d_2002.zip

* modis_albedo_hdeg/

modis_bsa_hd_2002.zip

modis_qa_hd_2002.zip

modis_wsa_hd_2002.zip

* modis_albedo_qdeg/

modis_bsa_qd_2002.zip

modis_qa_qd_2002.zip

modis_wsa_qd_2002.zip

Data file naming conventions are described in the 0_modis_albedo_2002_readme.txt

Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC)  [http://daac.ornl.gov].

Data Archive Contact Information:

E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952