CLPX-Satellite: AMSR-E Brightness Temperature Grids

Summary

This data set includes Aqua Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) passive microwave brightness temperatures gridded to the geographic (lat/long) and UTM grids of the Large Regional Study Area (LRSA) of the NASA Cold Land Processes Field Experiement (CLPX). Data are provided for passive microwave frequencies at 6.9, 10.7, 18.7,23.8, 36.5 and 89.0 GHz, separated by ascending and descending satellite passes, and include time files. These data are interpolated from swath data (Level 2A data, release B01) using inverse distance squared resampling. Satellite passive microwave brightness temperatures can be used to derive snow water equivalent.

These data cover the period 1 February 2003 through 31 May 2003. Resolution for both grids is approximately 25 km. There are 24 brightness temperature files per day for a given projection, and two corresponding time files. Data arrays are contained in flat binary files by channel, consisting of 2-byte unsigned integer arrays of brightness temperatures in tenths of Kelvins, or in the case of time files, 2-byte signed integer arrays representing Coordinated Universal Time (UTC) in minutes since midnight.

Citing These Data

Brodzik, M.J., Editor. 2003. CLPX-Satellite: AMSR-E Brightness Temperature Grids. Boulder, CO: National Snow and Ice Data Center. Digital Media.

Overview Table

Category	Description
Data format	Binary files
Spatial coverage	CLPX LRSA in Colorado and Wyoming Upper Left Boundary: 42 N, 108.5 W Lower Right Boundary: 38.5 N, 104 W
Temporal coverage and resolution	01 February - 31 May 2003.
Total File size	25 MB (uncompressed), 2.8 MB (compressed)
Parameter(s)	passive microwave brightness temperatures
Procedures for obtaining data	Data are available via FTP

1. Contacts
2. Detailed Data Description
3. Data Access
4. Data Acquisition
5. References and Related Publications
6. Document Information

1. Contacts

Investigator(s) Name and Title

Mary J. Brodzik
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

2. Detailed Data Description

This data set includes gridded passive microwave brightness temperatures. Data are provided for passive microwave frequencies at 6.9, 10.7, 18.7, 23.8, 36.5 and 89.0 GHz, separated by ascending and descending satellite passes, and include time files. Grid resolution is 25 km. The resampling method is inverse distance squared. Data are available in CLPX lrsa_geo720.0 and lrsa_utm25000 (see grid description). Temporal coverage is 1 February - 31 May 2003.

Format

There are 24 brightness temperature files per day for a given projection. Data are 2-byte unsigned integers, compressed, little-endian (i.e., PC or VAX) byte-order, representing temperatures in tenths of Kelvins. The fill value is 0.

There are two time files per day for a given projection. Data are 2-byte signed integers, representing minutes since midnight UTC. The fill value is -32768.

There are two geolocation files for each grid (geo and utm), with grid latitude and longitude coordinates. Data are 8-byte, little-endian, double-precision values, representing decimal degrees. File extension is .double.

File and Directory Structure:

Data are provided in a compressed (tarred and zipped) file named nsidc0145_amsre_vxx.tgz, where xx represents the data release version number. Within this compressed file, data files are in the following directory structure:

geo/
  2003/
     02/
       ID2-AMSRE-B01-LRSA_GEO720.0.01.2003032A.06H, etc.
     03/
     04/
     05/
lrsa_geo720.0.lat.23x18x1.double
lrsa_geo720.0.lon.23x18x1.double

utm/
  2003/
     02/
       ID2-AMSRE-B01-LRSA_UTM25000.01.2003032A.06H, etc.
     03/
     04/
     05/
lrsa_utm25000.lat.17x17x1.double 
lrsa_utm25000.lon.17x17x1.double

File Naming Convention

The compressed file is named nsidc0145_amsre_vxx.tgz, where xx represents the data release version number. Individual data files are named ID2-AMSRE-B01-ggg.vv.yyyydddp.ccc where

ID2: Brightness temperature interpolation method - inverse distance squared
AMSRE-B01: Source data - AMSR-E L2A version B01
ggg: grid name (LRSA_GEO720.0 or LRSA_UTM25000)
vv: 2-digit data version number
yyyy: 4-digit year
ddd: 3-digit day of year
p: pass direction, one of {A(scending), D(escending)}
ccc: channel/polarization or time, one of {06H, 06V, 10H, 10V, 23H, 23V, 36H, 36V, 89H, 89V, TIM}

For example, the file called ID2-AMSRE-B01-LRSA_UTM25000.01.2003150D.06H contains 6 GHz, horizontally-polarized brightness temperatures, descending passes only, for day 150 (May 30), 2003, gridded to the CLPX 25 km UTM grid, using an inverse distance squared interpolation method. The designator '.01.' indicates this is version 1 processing of these data.

File Size

Total file size is 25 MB (uncompressed), 2.8 MB (compressed). Individual files are less than 1 KB.

Spatial Coverage

This data set covers the CLPX LRSA in Colorado and Wyoming.

Upper Left Boundary: 42 N, 108.5 W
Lower Right Boundary: 38.5 N, 104 W

Spatial Coverage Map:

The following map shows the CLPX LRSA:

Spatial Resolution

Latitude_Resolution: GEO720.0: 0.2 degrees
Longitude_Resolution: GEO720.0: 0.2 degrees
Latitude_Resolution: UTM25000: 25000m
Longitude_Resolution: UTM25000: 25000m

Grid Description

Geographic (GEO) Grid: 23 cols x 18 rows
UL: 42.05N, 108.55W
LR: 38.45N, 103.95W

Universal Transverse Mercator (UTM) Grid: 17 cols x 17 rows
UL: 42.16N, 108.93W
LR: 38.39N, 103.85W

Please see Geographic grid description and Universal Transverse Mercator grid description for lrsa_geo720.0 and lrsa_utm25000 grids, respectively.

Temporal Coverage

Brightness temperature data were collected between 01 February and 31 May 2003.

Parameter or Variable

Parameters presented in this data set are passive microwave brightness temperatures (T_b).

3. Data Access

Data Access

Data are available via FTP

Related Data Collections

Cold Land Processes Field Experiment (CLPX)
DMSP SSM/I Pathfinder Daily EASE-Grid Brightness Temperatures
CLPX-Satellite: SSM/I Brightness Temperature Grids

Quality Assessment:

Selected brightness temperatures and time files have been visualized and manually inspected by data center operators before being archived and distributed.

4. Data Acquisition

Please see the AMSR-E sensor/instrument description. The source for the input L2A brightness temperature data is the National Snow and Ice Data Center.

5. References and Related Publications

Ashcroft, P., and F. Wentz. 2003. AMSR-E/Aqua L2A Global Swath Spatially-Resampled Brightness Temperatures V001 (September 2003). Boulder, CO, USA: National Snow and Ice Data Center. Digital media.

Ashcroft, P. and F. Wentz. 2000. Algorithm Theoretical Basis Document for the AMSR Level 2A Algorithm, Revised 03 November. Santa Rosa, CA, USA: Remote Sensing Systems.

Kelly, R. E, A. T. Chang, L. Tsang and J. L. Foster. 2003. A Prototype AMSR-E Global Snow Area and Snow Depth Algorithm. IEEE Transactions on Geoscience and Remote Sensing, 41(2), 230-242.

6. Document Information

List of Acronyms

AMSR-E = Advanced Microwave Scanning Radiometer - Earth Observing System
CLPX = NASA Cold Land Processes Field Experiment
IOP = Intensive Observation Period
ISA = Intensive Study Area
LRSA = Large Regional Study Area
LSOS = Local Scale Observation Site
MSA = Meso-cell Study Area
UTC = Coordinated Universal Time

Document Creation Date

11 February 2004

Service Interruption

National Snow and Ice Data Center