CLPX-Satellite: AVHRR/HRPT Brightness Temperatures and Reflectances
Summary
This data set includes AVHRR/HRPT (Advanced Very High Resolution Radiometer/High Resolution Picture Transmission) brightness temperatures and reflectances over the NASA Cold Land Processes Field Experiment (CLPX) Large Regional Study Area (LRSA) (NW corner: 42°N, 108.5°W, SE corner: 38.5°N 104°W). Data are gridded to the LRSA at 1.1 km (or 30 arc-second) resolution. Data were collected between November 2001 and June 2003. Reflectance files contain flat binary rasters of 2-byte unsigned integers representing albedo. The brightness temperature files contain 2-byte unsigned integers representing interpolated temperatures in tenths of degrees Kelvin.
Citing These Data
Cline, D. 2003. CLPX-Satellite: AVHRR/HRPT Brightness Temperatures and Reflectances. Boulder, CO: National Snow and Ice Data Center. Digital Media.
Overview Table
| Category | Description |
|---|---|
| Data format |
Reflectance files: flat binary rasters of 2-byte unsigned integers representing albedo. |
| Spatial coverage | CLPX LRSA in Colorado and Wyoming Upper left: 42°N, 108.5°W Lower right: 38.5°N 104°W |
| Temporal coverage and resolution | Sporadic coverage between 9 November 2001 and 26 June 2003 |
| Total File size | Compressed files range in size from 4.6 to 4.85 KB. |
| Parameter(s) | Brightness temperatures and reflectances |
| Procedures for obtaining data | Data are available via FTP |
Table of Contents
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
Don Cline
National Weather Service
National Operational Hydrologic Remote Sensing Center
1735 Lake Drive W.
Chanhassen, MN 55317
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
The Advanced Very High Resolution Radiometer (AVHRR) data set is comprised of data collected by the AVHRR sensor, carried aboard the National Oceanic and Atmospheric Administration's Polar Orbiting Environmental Satellite series. The AVHRR sensor is a broadband 5-channel scanning radiometer, sensing in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. Please refer to NOAA's AVHRR site for further information about this sensor.
This data set includes AVHRR/HRPT rasters; five bands co-registered to the UTM and Geographic (lat-lon) grids of the CLPX LRSA. Data are provided for the five wavelengths 0.63, 0.91, 1.61, 10.8 and 12.0 microns; HRPT channels 1, 2, 3a, 4 and 5. Data are calibrated to reflectance and brightness temperature using on-board coefficients, reprojected from swath space to geographic grid, and exported as 16-bit binary rasters. The data are also reprojected to UTM, Zone 13. Daylight passes were collected from NOAA-16 and NOAA-17.
Format
Reflectance files contain flat binary rasters of 2-byte unsigned integers. The values represent percent albedo, multiplied by 100, ranging from 0 to 10000. The brightness temperature files contain 2-byte unsigned integer representing interpolated temperatures in tenths of Kelvins. The values range roughly from 2300 to 3100. Data are gridded to the LRSA, at 1.1 km (or 30 arc-second) resolution.
File and Directory Structure:
Data are provided as tarred and zipped binary and tiff files; one each for UTM and geographic grids. Within the compressed files, the data structure is:
binary_geo.tgz/
2001-11-09.2030.noaa-16.geo.ch1.bil
2001-11-09.2030.noaa-16.geo.ch1.blw
2001-11-09.2030.noaa-16.geo.ch1.hdr
etc...
binary_utm.tgz/
2001-11-09.2030.noaa-16.utm.ch1.bil
2001-11-09.2030.noaa-16.utm.ch1.blw
2001-11-09.2030.noaa-16.utm.ch1.hdr
etc...
tiff_geo.tgz/
2001-11-09.2030.noaa-16.geo.ch1.tfw
2001-11-09.2030.noaa-16.geo.ch1.tif
2001-11-09.2030.noaa-16.geo.ch2.tfw
etc...
tiff_utm.tgz/
2001-11-09.2030.noaa-16.utm.ch1.tfw
2001-11-09.2030.noaa-16.utm.ch1.tif
2001-11-09.2030.noaa-16.utm.ch2.tfw
etc...
lrsa-meta.tgz/
2001-11-09.2030.noaa-16.geo.ch1.blw
2001-11-09.2030.noaa-16.geo.ch1.meta
etc...
File Naming Convention
Compressed files are named binary_geo.tgz, binary_utm.tgz, tiff_geo.tgz, and tiff_utm.tgz. WIthin the compressed files, individual data files are named as follows.
Raw reflectance data files are named YYYY-MM-DD.HHMM.noaa-SS, where
YYY = Year
MM = Month
DD = Day
HHMM = Hour Minute
SS = Satellite number (16 or 17).
Processed data files are split into two subdirectories, binary and tiff. Within each subdirectory data have been reprojected into Geographic and UTM formats. The file naming structure for binary data in geographic format is YYYY-MM-DD.HHMM.noaa-SS.geo.chX, where
YYY = Year
MM = Month
DD = Day
HHMM = Hour Minute
SS = Satellite number (16 or 17)
X = Channel (1, 2, 3a, 4 and 5).
Each file is available in *.bil (binary interleaved by line), *.blw (georeferencing information) and *.hdr (standard header information) formats. The file naming structure for binary data in UTM format is similar to the geographic format, except for the use of ‘utm' instead of ‘geo' in the file naming format. For example:
YYYY-MM-DD.HHMM.noaa-SS.utm.chX
The tiff subdirectories follow the same file naming structure for both Geographic and UTM reprojections as the binary subdirectories. However the file types in the tiff subdirectory are *.tif (image files) and *.tfw (header files for TIF files).
Metadata files are available to support each AVHRR scene, in both UTM and Geographic reprojections. Metadata files follow the same naming structure as the processed data files but with *.meta file types.
File Size
Compressed files range in size from 4.6 to 4.85 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
Data are gridded to the LRSA, at 1.1 km (or 30 arc-second) resolution.
Spatial Coverage Map:
The following map shows the CLPX LRSA:
Temporal Coverage
Data were collected between 9 November 2001 and 26 June 2003. The complete temporal coverage is given in the following table.
Year
Month
Day
Time
2001
11
9
2030
2001
12
7
2050
2002
2
12
2005
2002
2
20
2034
2002
3
1
2037
2002
3
9
2052
2002
3
12
2017
2002
3
13
2006
2002
3
20
2032
2002
3
21
2020
2002
3
22
2009
2002
3
31
2012
2002
4
8
2025
2002
4
10
2003
2002
4
17
2028
2002
4
28
2008
2002
5
5
2034
2002
5
6
2023
2002
5
7
2012
2002
12
2
2020
2002
12
5
1717
2002
12
23
1713
2003
1
7
2021
2003
1
17
1752
2003
1
21
1802
2003
1
23
1722
2003
1
27
1732
2003
1
29
1828
2003
2
3
2021
2003
2
10
1712
2003
2
12
1807
2003
2
17
1756
2003
2
18
1732
2003
2
22
2008
2003
2
27
1724
2003
3
3
1739
2003
3
10
2032
2003
6
13
1744
2003
6
17
1753
2003
6
21
1804
2003
6
22
1741
2003
6
24
2050
2003
6
25
1814
2003
6
26
1751
Parameter or Variable
Parameters presented in this data set are brightness temperatures and reflectances.
Sample Data Record
Accompanying the raw data files are header files (*.hdr) that provide information about each raw reflectance file. An example of a header files is shown below.
Space Science & Engineering Center
University of Wisconsin - Madison
Man computer Interactive Data Access System (McIDAS)
Satellite: NOAA-16 SSEC ID Number: 66
Image Date: 7 DEC 01 (YYDDD=01341) Image Start Time: 20:36:29 GMT
IMAGE COORDINATES
Start Line Start Element Line Resolution Element Resolution
1240 284 1 1
IMAGE FILE(S)
File Name Parameter Unit Band Lines Elements Element Format Scale
------------ ------------ ---- ---- ------- -------- ------------------ -----
W341.HDR Header ASCII (80 Chars)
W341.001 Raw Sensor none 1 2000 1400 Int (16 bit) 1
W341.002 Raw Sensor none 2 2000 1400 Int (16 bit) 1
W341.003 Raw Sensor none 4 2000 1400 Int (16 bit) 1
W341.004 Raw Sensor none 5 2000 1400 Int (16 bit) 1
W341.005 Raw Sensor none 6 2000 1400 Int (16 bit) 1
W341.LAT Latitude NA 2000 1400 Integer (16 bit) 100
W341.LON Longitude NA 2000 1400 Integer (16 bit) 100
* - Navigation files resolution: 1 Lat/Lon per every 1 image element(s)
* - Navigation files missing data value = 65535
SSEC NAVIGATION BLOCK (All nonzero entries)
1. TIRO 2. 6601341 3. 203259 4. 1
5. 11209 6. 12246 7. 722992 8. 1094
9. 98849 10. 260389 11. 99859 12. 286025
13. 2048 14. 54128 15. 621 46. 1
47. 1040 48. 73979117 49. 167 51. 2200
52. 2048 53. 166667 54. 8138
The following is an example of a UTM metadata file:
HRPT data for LRSA Date: 2001-11-09 Time: 2030 Satellite: NOAA-16 Upper Left latitude: 42.04999923706055 Upper Left longitude: -108.55000305175781 Lower Right latitude: 38.45 Lower Right longitude: -103.95 Datum: WGS84 Approximate coverage: 4.6 x 3.6 degrees =~ 400km x 400km UTM Grid Zone: 13 Semi-Major Axis of Ellipsoid: 6378137.000 meters Semi-Minor Axis of Ellipsoid: 6356752.314245 meters Scale Factor of C Meridian: 0.999600 Longitude of Central Meridian: -105.0000 degrees Upper Left XY: 175000.0, 4675000.0 = 42.159677085 M. 108.933826235 W Lower Right XY: 600000.0, 4250000.0 = 38.392627781 N, 103.854898585 W Datum: WGS84 X resolution: 816.83574327477345 Y resolution: -816.83574327477345 Upper Left X: 190250.60697080070000 Upper Left Y: 4661756.31889947410000 Rows: 497 Columns: 491 Nbits: 16 Nbands: 1
3. Data Access
Data Access
Data are available via FTP at ftp://sidads.colorado.edu/pub/DATASETS/CLP/data/satellite/nsidc0152_avhrr/.
Related Data Collections
All CLPX Data Sets
AVHRR Data at NSIDC
Quality Assessment:
The AVHRR sensor was designed to view cold space and one or more internal warm blackbodies for each scan sequence while in orbit. In general, radiometric calibration involves exposing a radiometer to sources of radiation that have been calibrated against primary or secondary standards and determining a relationship between the output of the radiometer and the intensity of the incident radiation (radiance). All of the radiometers flown on the NOAA/TIROS satellites undergo extensive prelaunch testing and calibration by their manufacturers to characterize their performance.
As the spacecraft moves through its orbit, the expected angular distance between the nadir of adjacent LAC/HRPT scans is approximately 0.0296 degrees of arc, or 3.2914 kilometers, as measured from the center of Earth. The actual value of the average angular distance can vary by up to about 0.1712 kilometers due to variations in satellite height, scan angle, and other factors. The instantaneous field-of-view (IFOV) for all channels is specified to be 1.3 +/- 0.1 milliradians.
4. Data Acquisition
These data were captured on a McIDAS SDI system and processed in the McIDAS software package (a suite of applications for analyzing and displaying meteorological data). Data are calibrated to reflectance and brightness temperature using on-board coefficients, reprojected from swath space to geographic grid, and exported as 16-bit binary rasters. The data are also reprojected to UTM, Zone 13.
6. Document Information
List of Acronyms
AVHRR =
Advanced Very High Resolution Radiometer
CLPX = NASA Cold Land Processes Field Experiment
HRPT =
High Resolution Picture Transmission
IOP = Intensive Observation Period
ISA = Intensive Study Area
LRSA = Large Regional Study Area
LSOS = Local Scale Observation Site
MSA = Meso-cell Study Area
Document Creation Date
19 February 2004
Document URL
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