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Baltic Sea Experiment (BALTEX) Ground-Based Radar Polar Volume Data


This data set includes non-Doppler polar volume reflectivity data from the Baltic Sea Experiment (BALTEX). Data were collected on Sweden's Gotland Island, using an Ericsson radar mounted at 56 m above sea level. The radar provided 12 scanning angles. Measurements were taken between 1 September 2002 and 31 May 2003. BALTEX data sets will be used for validation of AMSR-E and Advanced Microwave Sounding Unit (AMSU)/Humidity Sounder for Brazil (HSB) Level 1 brightness temperatures and Level 2 cloud and precipitation parameters. Data are available in network Common Data Format (netCDF) from NSIDC via FTP.

The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) is a mission instrument launched aboard NASA's Aqua Satellite on 4 May 2002. The Baltic Sea Experiment's (BALTEX) Radar Data Centre (BRDC), operated by the Swedish Meteorological and Hydrological Institute (SMHI), collects data from as many radars in or near the Baltic region as possible. During the Main Observational Phase (October 1999 - February 2002), data from 25 radars in six countries covered the Baltic region every 15 minutes. High-latitude data are recorded from 50 to 70 ° North, and they complement pre-existing efforts in the mid-latitudes and tropics.

Citing These Data

Bennartz, R. 2004. Baltic Sea Experiment (BALTEX) Ground-Based Radar Polar Volume Data. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.

Overview Table

Category Description
Data format netCDF
Spatial coverage and resolution 57.24°N, 18.39°E
Temporal coverage and resolution 1 September 2002 to 31 May, 2003, in 15-minute intervals
Tools for accessing data Use an appropriate application to view netCDF data
File naming convention File strings describe file contents, including the radar, place, date, and time
File size 2.3 MB
Parameter(s) Reflectivity (dBz)
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

Ralf Bennartz
University of Wisconsin-Madison
Daniel Michelson
Swedish Meteorological and Hydrological Institute

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services

2. Detailed Data Description


Data are provided in netCDF format. The netCDF headers contain dimensions, units, and other information.

File and Directory Structure

There is a tar file on the FTP site for each month data were collected.

File Naming Convention

File strings describe file contents, including the non-doppler radar (znp), place, date, and time. For instance, the file "" indicates that the data were collected from Hemse radar station at 1 hour 45 minutes in UTC on 31 May 31 2003.

File Size

Each data file is 2.3 MB.

Spatial Coverage

57.24°N, 18.39°E

Temporal Coverage

1 September 2002 to 31 May, 2003.

Temporal Resolution

Data are given in 15-minute intervals.

Parameter or Variable

Parameter Description

The parameter measured in this data set is reflectivity.

The following table shows the scanning angle for the 12 scans in each data file.

Scan Angle
(elevation angle in degrees)
1 0.5
2 0.7
3 0.9
4 1.1
5 1.5
6 2.3
7 3.2
8 4.1
9 6.0
10 12.0
11 24.0
12 40.0

Unit of Measurement

Reflectivity is given in dBz.

Parameter Source

The measurements were taken from the Gotland Island Hemse radar station.

Sample Data Record

The following shows scan 1 of the data file ""

Scan 1 figure

3. Data Access and Tools

Data Access

Data are available via FTP.


Data files are contained in compressed tar files, one file for each month. The total compressed volume is 212 MB.

Software and Tools

Use an appropriate application to view netCDF data.

The netCDF format is an interface for array-oriented data access with an interface library. The netCDF library also defines a machine-independent format for representing scientific data. Together, the interface, library, and format support creating, accessing, and sharing scientific data. The netCDF software was developed at the Unidata Program Center in Boulder, Colorado. More information about netCDF and software for manipulating and displaying NetCDF is available from Unidata.

Related Data Collections

4. Data Acquisition and Processing

Theory of Measurements

Data Acquisition Methods

The following table provides information about the Hemse radar station, the instrument, and data acquisition.

Radar System Ericsson EWR Radar
Wavelength 5.31 cm
Location Gotland Island (57.24 ° North, 18.39 ° East), Sweden
Processing Software Ericsson Enterprise Wireless Internet Solutions (EWIS)
Height of the antenna 56 m above sea level
Distance between two successive range bins 2,000 m
Number of range bins in each ray 120 (with 2,000 m spacing)
Number of azimuth gates (rays) per scan 480 (starting North, clockwise)
Half-power beamwidth 0.9 °
Antenna speed in revolutions per minute 6
Pulse width 2 ms
Low-pulse repetition frequency 250 Hz
High-pulse repetition frequency 250 Hz
How raw data in range are processed to arrive at the given value average

5. References and Related Publications

BALTEX Radar Data Centre

Global Energy and Water Experiment BALTEX site

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
AMSU Advanced Microwave Sounding Unit
BALTEX Baltic Sea Experiment
BRDC BALTEX Radar Data Centre
dBz Decibels Reflectivity
EWIS Enterprise Wireless Internet Solutions
FTP File Transfer Protocol
HSB Humidity Sounder for Brazil
netCDF Network Common Data Format
SMHI Swedish Meteorological and Hydrological Institute

Document Creation Date

April 2004

Document URL