THE WIND IMAGING INTERFEROMETER (WINDII) ON THE UPPER ATMOSPHERE RESEARCH SATELLITE (UARS)

Objective/Purpose

WINDII measures wind, temperature, and emission rates in the upper mesosphere and lower thermosphere (80 to 300 km) from observations of the Earth's airglow. Measurements are made both day and night providing global coverage of this region of the atmosphere.

Instrument

The Wind Imaging Interferometer (WINDII) was launched on the NASA's Upper Atmosphere Research Satellite on 12 September 1991 and operated until June 2004.

The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(¹S) and O(¹D) lines, as well as lines in the OH Meinel (8,3) and O₂ Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements.

Although the WINDII was included as part of the UARS mission primarily for its wind measuring capabilities, its ability to simultaneously measure airglow radiance proved almost as important and provided another valuable means to observe dynamical signatures in the mesosphere and thermosphere. The airglow emissions observed were the O(¹S) and O(¹D) atomic oxygen lines, the OH (8,3) band P₁(2) and P₁(3) lines, the O⁺(²P) ionized atomic oxygen line pair at 732 and 733 nm, and the ^PP(7) and ^PQ(7) lines in the O₂ (0-0) atmospheric band. The latter pair required an etalon for their spectral separation, which resolved the lines into two rings on the image.

Data access

WINDII data have been processed to levels 1, 2, 3AL and 3AT. WINDII level 3A version 9 data products are available from the Goddard Space Flight Center (GSFC) Distributed Active Archive Center (DAAC).

Data Set Identification:

UARS WINDII LEVEL 3AL DAILY LATITUDE ORDERED DATA

UARS WINDII LEVEL 3AT DAILY TIME ORDERED DATA

Data Set Introduction:

The WINDII level 3A data are a subset of the UARS dataset. The WINDII data are archived as two data products at the DAAC:

• WINDII level 3AL data are daily latitude- and time-ordered data interpolated to intervals of 4 degrees latitude at the intersection of the tangent track of the instrument's line of sight (LOS). Each record consists of a single array of data of one parameter for a specific time. Level 3AL data records are written to UARS defined standard latitudes, which range from -88 to +88 degrees in 4 degree intervals.
• WINDII level 3AT data are daily time-ordered data, arranged at time intervals of 65.536 seconds, or about 495 km intervals along the LOS tangent track. The reference time at which level 3AT data are arranged is common across all UARS level 3AT files.

The WINDII Level 3AL and 3AT data are written as Standard Data Format Units (SFDU) files. Each file consists of three records called SFDU, LABEL, and DATA. The SFDU and LABEL records contain descriptive information about the instrument and the data, such as start/stop time of the data, number of records in the file, etc. The data record contains the profile data and their standard deviations. Time, latitude longitude, local solar time, and solar zenith angles are provided with each data record. Each data file is accompanied by a short ASCII metadata file, which provides descriptive information such as the start and stop time of the data, file record lengths, and the UARS quality flag.

After the original level 3A file formats were agreed to, it was realized that additional parameters were needed to describe the WINDII data. Level 3LP and 3TP parameter files were created to include values for the WINDII JOB version number, CDB version number, inversion quantity flag, temperature source flag, and filter number and quality flag. Each level 3AL file for a given day is accompanied by a level 3LP file. Similarly, each level 3AT file for a given day is accompanied by a level 3TP file. The 3LP and 3TP files also consist of the three record types SFDU, LABEL and DATA, and are also accompanied by their own ASCII metadata files.

Contact

Principle Investigator

Dr. Gordon Shepherd
Department of Earth and Atmospheric Sciences
York University
4700 Keele Street
North York, Ontario
Canada, M3J 1P3
gordon@windic.yorku.ca

Links

• WINDII Instrument Home page.