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Meltpond2000 Polarimetric Scanning Radiometer Sea Ice Brightness Temperatures

Summary

The Meltpond2000 project was the first in a series of Arctic and Antarctic aircraft campaigns to validate sea ice algorithms developed for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), primarily to quantify errors in AMSR-E sea ice products resulting from the presence of melt ponds. The AMSR-E validation effort addresses data quality through comprehensive calibration and validation programs. These programs characterize and document the accuracy and precision of AMSR-E observations and their derived products.

Data were collected from five flights over Baffin Bay and the Canadian Archipelago from 26 June 2000 to 5 July 2000. All measurements fall within 68.967°N - 76.422°N, 63.197°W - 105.022°E. Spatial resolution varies from 0.13 km to 3.6 km, depending on the sensor. Data are provided as MATLAB files, requiring MATLAB version 5.3 or greater. These data and MATLAB programs to generate brightness temperature (TB) maps are available via FTP.

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

Klein, M., A. J. Gasiewski, D. J. Cavalieri, and T. Markus. 2004. Meltpond2000 Polarimetric Scanning Radiometer Sea Ice Brightness Temperatures. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.

Overview Table

Category Description
Data format

Data are provided as MATLAB files. MATLAB version 5.3 or greater is required to view these data.

Spatial coverage and resolution

Data were collected from five flights over Baffin Bay and the Canadian Archipelago.

Southernmost Latitude: 68.966944
Northernmost Latitude: 76.421944
Westernmost Longitude: -105.021944
Easternmost Longitude: -63.196944
Minimum Altitude: 4500 ft
Maximum Altitude: 19000 ft

Spatial resolution varies from 0.13 km to 3.6 km, depending on the sensor.

Temporal coverage and resolution

Five eight-hour-long flights provided TB measurements on 26, 27, 29, 30 June 2000, and 5 July 2000.

Tools for accessing data

MATLAB programs to display TB maps are available via FTP.

File naming convention

Data files are named "L23axxxx.mat" where xxxx represents the serial number of the flight maneuver.

File size

Data files (*.mat) range from 24 KB to 32 MB.

Parameter(s)

Brightness temperatures (TBs)

Procedures for obtaining data

Data are available via FTP.

Table of Contents

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

1. Contacts and Acknowledgments

Investigator(s) Name and Title

Marian Klein and Albin J. Gasiewski
NOAA Environmental Technology Laboratory
Boulder, CO, USA

Donald Cavalieri and Thorsten Markus
Code 970
NASA Goddard Space Flight Center
Greenbelt, MD, USA  20771

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

Acknowledgements

The investigators would like to recognize B. Boba Stankov and Alvaro Ivanoff for their contributions to Meltpond2000.

2. Detailed Data Description

The Meltpond2000 project was the first in a series of Arctic and Antarctic aircraft campaigns to validate sea ice algorithms developed for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), primarily to quantify errors in AMSR-E sea ice products resulting from the presence of melt ponds. The objective was to compare sea ice concentrations derived from AMSR-E algorithms but using Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) radiances, with coincident observations from aircraft sensors and high-resolution satellite imagery. A secondary objective of the mission was to develop a microwave capability to discriminate between melt ponds and sea water using low-frequency microwave radiometers (Cavalieri 2000).

The Arctic field campaign was conducted between 25 June 2000 and 6 July 2000 from Thule, Greenland, with five eight-hour-long flights in a U.S. Navy P-3 Orion aircraft over melting ice floes in Baffin Bay and the Canadian Arctic. The P-3 carried several sensors operated by the NOAA Environmental Technology Laboratory's (ETL's) Microwave Radiometry Group, including two Polarimetric Scanning Radiometers (PSR/A and PSR/C), a Scanning Low-Frequency Microwave Radiometer (SLFMR), and an infrared scanner boresighted to each PSR.

Format

Data are provided as MATLAB files; MATLAB version 5.3 or greater is required to view these data. For a summary of the MATLAB file structure in this data set, please refer to Meltpond 2000 PSR Processing - Final Report (PDF file, 857 KB), under the heading "Level 2.3a data format description for PSR/A, PSR/C, and SLFMR instruments."

File and Directory Structure

This data set contains the following directories on the FTP site:

Directory Description
2000_0626
2000_0627
2000_0629
2000_0630
2000_0705
Flight code directories indicate the year, month, and day of the beginning of the flight. Within each of these directories is a "level2.3a" subdirectory that contains data files (*.mat) from PSR sensors and a "level2.3a_slfmr" subdirectory that contains data files (*.mat) from the SLFMR sensor.
display_23a Contains MATLAB version 5.3 executable files (*.m) necessary to render TB maps from PSR and SLFMR data.
documents Contains a file called "Final_Processing_Report.pdf," which is Klein and Gasiewski (2002) appended with Klein et al. (2001).

File Naming Convention

Data files are named "L23axxxx.mat" where xxxx represents the serial number of the flight maneuver. Please refer to Meltpond 2000 PSR Processing - Final Report (PDF file, 857 KB) for a list of maneuvers and their corresponding times and locations.

File Size

Data files (*.mat) range from 24 KB to 32 MB.

Spatial Coverage

Southernmost Latitude: 68.966944
Northernmost Latitude: 76.421944
Westernmost Longitude: -105.021944
Easternmost Longitude: -63.196944
Minimum Altitude: 4500 ft
Maximum Altitude: 19000 ft

Spatial Coverage Map

Click the following thumbnails to see larger maps of Meltpond2000 flight paths.


June 26

June 27

June 29

June 30

July 5
 

The Goddard Space Flight Center's (GSFC) Meltpond2000 site also provides maps of the Meltpond2000 region and flight paths.

Spatial Resolution

Resolution varies by sensor, as shown in the following table (from Klein and Gasiewski 2002):

Meltpond2000 Flight Summary
Date Region Altitude Sensor Channels Resolution
2000-06-26 Baffin Bay 5800 m PSR/A 10.7 GHz, 18.7 GHz, 21 GHz 2 km
37 GHz, 89 GHz 0.6 km
SLFMR 1.413 GHz 3.3 km
2000-06-27 Baffin Bay 1400 m PSR/A 10.7 GHz, 18.7 GHz, 21 GHz 0.5 km
37 GHz, 89 GHz 0.13 km
SLFMR 1.413 GHz 0.8 km
2000-06-29 Viscount Melville Sound
Ice Camp
1500 m and 300 m PSR/A 10.7 GHz, 18.7 GHz, 21 GHz 0.5 km
37 GHz, 89 GHz 0.13 km
SLFMR 1.413 GHz 0.8 km
2000-06-30 V Melville Sound
Ice Camp
4600 m and 300 m PSR/C 5.985 GHz, 6.485 GHz, 6.925 GHz, 7.325 GHz 2 km
SLFMR 1.413 GHz 2.6 km
2000-07-05 Baffin Bay 6400 m PSR/C 5.985 GHz, 6.485 GHz, 6.925 GHz, 7.325 GHz 2.7 km
SLFMR 1.413 GHz 3.6 km

Temporal Coverage

Five eight-hour-long flights provided TB measurements on 26, 27, 29, 30 June 2000, and 5 July 2000.

Parameter or Variable

Unit of Measurement

Brightness temperatures (TBs) are given in Kelvins.

Sample Data Record

A sample TB map is provided at the end of the Software and Tools section of this document.

Quality Assessment

Data in the TB maps are not compensated for incident angle variations caused either by aicraft roll and pitch or, in the case of the SLFMR, by the cross-track scanning mode. Although the PSR scans at fixed angles, aircraft pitch and roll variations influence the incident angle by as much as ±3° in angle, or roughly ±7 K for vertical and ±4 K for horizontal polarization over water. All channels worked well providing approximately 0.5 K to 1 K root-mean-square (RMS) noise for 20 ms integration. One exception was the 89 GHz vertical channel, which was not calibrated due to spurious noise (Klein et al. 2001). The 89 GHz noise is presumed to be from iron epoxy debris on the sensor.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The full data set is approximately 647 MB.

Software and Tools

Data are provided as MATLAB files; MATLAB version 5.3 or greater is required to view these data. The MATLAB programs to display TB maps are available via FTP. Download all files to your computer, organizing them in the same directory structure as on the FTP site. The full data set is approximately 647 MB. Then perform the following steps, which were tested at NSIDC on a Windows 2000 PC.

1. Edit the file "setrootdir.m" (found in the "display_23a" directory) so the variable "rootdir" indicates the proper path to your root directory.

Special note for UNIX users: these Matlab executables were originally written for a Windows PC platform. To run them correctly on a Unix or Linux server, change the backslashes (\) to forward slashes (/) in the following line of code in "mainshelldisp23a.m":

cd([rootdir dirstrg '\' leveldir '\SL']);

2. Edit the MATLAB path to point to the directory "display_23a." To do this, open MATLAB, select File, Set Path, and Add with Subfolders. Type the path to the "display_23a" directory, click Save, and then Close.

3. At the MATLAB prompt, type "mapl23a". The program asks you to select an instrument (PSR or SLFMR), followed by the available dates, and flight codes available for that date. (Please refer to Meltpond 2000 PSR Processing - Final Report (PDF file, 857 KB) for a list of maneuvers and their corresponding times and locations.)

4. The program prompts you for one or more channels to display. Several channel groups are provided in the command line. The next variables that can be selected are the minimum and maximum TBs for the range of the color map. If you define the minimum color temperature, you will be asked for the maximum; otherwise, the program automatically assigns these values. If you select auto-range calculation, the program attempts to fit a Gaussian probability function to the TB histogram and computes the color range individually for each channel using the Gaussian parameters with a range factor. The range factor sets the color range relative to the mean by the indicated number of standard deviations. It defaults to 0.6, but you can modify it according to your needs. Autocalculation is useful for scenes where the TBs fall within a narrow range of values.

5. You can display a portion of a maneuver by selecting a sample of scans from all scans available. For conical scanning, one full scan means one full rotation around the azimuth axis with front and back views.

6. You can produce either individual maps (one image for each channel) or composite images of all channels and views in a single map.

7. Finally, you can select new latitude and longitude corners if you prefer. If you have installed the MATLAB Mapping Toolbox, you can choose whether to include U.S. state boundaries on the final map.

Following is a screen capture of an individual TB map generated from the file "L23a0131.mat," 27 June 2000, at 18.7 GHz:

L23a0131

Related Data Collections

4. Data Acquisition and Processing

Sensor or Instrument Description

A U.S. Navy P-3 Orion aircraft carried the following sensors from NOAA ETL:

The two PSR sensors covered the full range of AMSR-E frequencies (6.9 GHz to 89.0 GHz). In addition, the P-3 carried NASA GSFC video and digital cameras.

The PSR has three main components: a scanhead, a positioner, and aircraft control and acquisition electronics. Several scanning modes are programmable, including conical, cross-track, and along-track. The preferred scanning mode of the PSR during Meltpond2000 was full-conical (360° in azimuth) with a 55° incident angle.

The SLFMR is a cross-track scanning radiometer operating at a center frequency of 1.41 GHz with a bandwith of 100 MHz. The electronically steerable scan consists of eight vertically polarized beams (four on port and four on starboard) with incident angles varying from 6° to 47° from nadir. During the Meltpond2000 campaign, only the four outermost beams were available due to an electronic failure, so only data with incident angles of 36° and 47° on both sides of the aircraft were available (Klein et al. (2001)).

The following table from Klein et al. (2001) lists channels and polarizations for the scanheads.

Instruments and Channels Used in Meltpond2000
Channel Frequency Polarization Scanhead
1.413 GHz Vertical SLFMR
5.985 GHz Vertical, horizontal PSR/C
6.485 GHz Vertical, horizontal
6.925 GHz Vertical, horizontal
7.325 GHz Vertical, horizontal
10.7 GHz Vertical, horizontal PSR/A
18.7 GHz Vertical, horizontal
21.5 GHz Vertical, horizontal
37 GHz Vertical, horizontal
89 GHz Vertical (noisy), horizontal
9.5 µm - 11 µm   PSR/A and PSR/C
RGB video camera   PSR/A and PSR/C

More detailed information about the PSR is available from NOAA ETL.

Data Acquisition Methods

For each of the flights, only one PSR (A or C) was flown because of the availability of only one PSR positioner. The June 26 flight over Baffin Bay, at an altitude of 5,800 m, coincided with visible Landsat-7 and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) data, covering many SSM/I footprints. The June 27 flight over Baffin Bay, at an altitude of 1,400 m, allowed a Navy ice observer to have a better view of surface conditions while still covering several SSM/I footprints. (SSM/I data were run through the AMSR-E sea ice algorithm to calculate ice concentration.) This flight was nested within the June 26 flight pattern. The July 5 flight over Baffin Bay used the PSR/C scanhead in order to map the ice cover with a low-frequency radiometer.

The June 29 and June 30 flights were made at an altitude of 300 m over the Canadian ice camp near Resolute Bay in the Canadian Archipelago. This allowed the highest possible spatial resolution with the microwave radiometers. Because of the low altitude, the sensors were operated in stare mode to provide uninterrupted measurements along the flight track. On June 29, the P-3 carried the PSR/A scanhead; on June 30, it carried the PSR/C. Canadian researchers at the ice camp collected coincident ice surface and meteorological data, including melt pond temperatures, as part of the Collaborative-Interdisciplinary Cryospheric Experiment (C-ICE). These ice camp flights were made in combination with flights over Viscount Melville Sound, along tracks consistent with surface measurements. The first flight over Viscount Melville Sound was at 1,500 m altitude, and the second flight was at 4,600 m altitude (Cavalieri 2000).

5. References and Related Publications

Cavalieri, D.J. 2000. EOS Aqua AMSR-E sea ice validation program: Meltpond2000 flight report. NASA Technical Memorandum, NASA/TM 2000-209972. Greenbelt, MD, USA: NASA Goddard Space Flight Center.

Ivanoff, A. "Meltpond2000." Sea Ice Remote Sensing. 23 May 2003.
http://polynya.gsfc.nasa.gov/seaice_mp2000.html.
Accessed January 2004.

Klein, M., A. J. Gasiewski, K. Schuler, D. Cavalieri, T. Markus, and A. Yevgrafov. 2001. Sea ice brightness imagery observed during the Meltpond 2002 experiment. In Scanning the present and resolving the future, Proceedings of the International Geoscience and Remote Sensing Symposium, 2001. Vol. VI, p. 2853-2855.

Klein, M., and A. J. Gasiewski. 2002. Meltpond 2000 PSR processing - final report. Boulder, CO, USA: NOAA Environmental Technology Laboratory.

Klein, M., and A. J. Gasiewski. 2000. CAMEX3 polarimetric scanning radiometer MATLAB mapping software description. Boulder, CO, USA: NOAA Environmental Technology Laboratory.

Markus, T., D. J. Cavalieri, and A. Ivanoff. 2002. The potential of using Landsat 7 data for the classification of sea ice surface conditions during summer. Annals of Glaciology 34: 415-419.

Markus, T., D. J. Cavalieri, M. A. Tschudi, and A. Ivanoff. 2003. Comparison of aerial video and Landsat 7 data over ponded sea ice. Remote Sensing of the Environment 86: 458-469.

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AMSR-E Advanced Microwave Scanning Radiometer - Earth Observing system
C-ICE Collaborative-Interdisciplinary Cryospheric Experiment
DMSP Defense Meteorological Satellite Program
ETL Environmental Technology Laboratory
MODIS Moderate Resolution Imaging Spectroradiometer
NOAA National Oceanic and Atmospheric Administration
PSR Polarimetric Scanning Radiometer
RMS Root-Mean-Square
SLFMR Scanning Low-Frequency Microwave Radiometer
SSM/I Special Sensor Microwave/Imager
TB Brightness Temperature

Document Creation Date

February 2004

Document Revision Date

February 2004

Document Review Date

February 2004

Document URL

http://nsidc.org/data/docs/daac/nsidc0208_meltpond2000.gd.html