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4. Fabry-Perot_Spectrometer

Description

The spectrometers are currently based at Mawson and Davis. This record details thermospheric and mesospheric winds, temperatures, and emission intensities from the Fabry Perot Spectrometer. See the publications database for a list of references associated with the project - ASAC projects 514 and 2699.

Project objectives:
The principle aim of the project is to detect upwellings in thermospheric wind, characterise their properties at different levels in the thermosphere (~100 km and ~200 km altitude); and determine their impact on the mesosphere and ionosphere.

The project will also:
(i) systematically study the dynamics and thermodynamics of the Antarctic thermosphere and mesosphere by observing the winds and temperatures in these regions;

(ii) identify the propagation of atmospheric gravity waves (AGWs) in the thermosphere and mesosphere;

(iii) investigate the sources of AGWs in the thermosphere and their impact on the ionosphere;

(iv) monitor the long term behaviour of the thermosphere and mesosphere for changes possibly related to global change;

Taken from the 2008-2009 Progress Report:
Public summary of the season progress:
The Davis Fabry-Perot Spectrometer, installed in 2003-04, continues to operate successfully and autonomously. Yearly modifications have improved the quality of observations and the instrument's reliability. Data is downloaded periodically to La Trobe University to monitor performance and new campaign modes are uploaded from La Trobe. The successful 2008 operations provided new observations on the behaviour of winds and temperatures in the thermosphere, a region of the atmosphere drastically affected by space weather. Current research concentrates on investigating the high-latitude sources of atmospheric gravity waves, and processes that control the more regular, daily, seasonal and annual variations in wind and temperature.

Taken from the 2009-2010 Progress Report:
Public summary of the season progress:
There is a high degree of symmetry in the charged particle energy inputs to the northern and southern hemisphere that drive auroral processes. Results from this project combined with simultaneous observations in Scandinavia have shown for the first time that winds at heights of about 250 km in the thermospheric region of the neutral atmosphere respond rapidly to the motions in the auroral ionosphere and also have a high degree of symmetry.

Quality

Raw data are in a standard format. Data for only some years are available.

Taken from the 2008-2009 Progress Report:
Difficulties affecting project:
Issues of instrumental differences between the Davis and Mawson FPSs that affect the interpretation, particularly of common volume measurements, need to be resolved. These have now been largely resolved but as a consequence there has been a delay in publishing some results. Some of the problems have related to behaviour of the EMCCD Camera and these have been of a nature which could only be identified by careful examination of actual data images.

Taken from the 2009-2010 Progress Report:
Difficulties affecting project:
The Davis FPS continues to operate satisfactorily and there have been no major difficulties with its operation. This success is due primarily to the fact that Mr Davies has been able to spend a significant amount of time at Davis each summer to service the instrument.

In contrast there is a major problem with the Mawson FPS as the imaging detector failed during 2009. These detectors cost ~$50K so we could not afford to have a backup at Mawson. Of course these detectors have a limited lifetime and it is unpredictable when and why they will fail. Attempts to diagnose and repair the detector during the 2009/10 summer were ultimately unsuccessful. As a result the instrument will not operate during 2010 and we will seek to have it repaired for re-installation over the 2010/11 summer. The filter wheel on the instrument also failed during 2008 and 2009. The new control system for the filter wheel will be commissioned next season.


A pair of files is generated for each observation, a JPG file which is a photograph of interference fringes, and a SPECS file that contains information about the observation. SPECS files are binary files so they can only be read by a program designed to read them.

Attached is a file containing a program that will open SPECS files. Please change the file extension from 'tmp' to 'exe'. Operation of the program is hopefully reasonably intuitive. Select the required folder then click on the file that you want to open. A screen shot is also attached.

Information about the observation is at the top of the screen from left to right as follows:

- 'psm' then the time in seconds that the spectrometer took to move it's periscope and point it at the appropriate part of the sky.
- The direction of observation. In the screen shot the direction is "Mawson cv" meaning that the spectrometer was looking at the common volume of sky between Davis and Mawson.
- Following "IS" the optimum exposure time in seconds (given to the nearest whole number) that the computer has calculated.
- UT time of the observation.
- Date of the observation.

In the top right hand corner are listed:
- Coordinates in pixels of the centre of the fringe pattern used in calculations.
- An estimate of the actual exposure time.
- The angle of elevation above the horizon of the field of view i.e. the elevation of the periscope.

The top plot shows the shape of the spectra derived from interference fringes. The vertical axis is approximately proportional to intensity and the horizontal axis gives an indication of changing wavelength. The red plot is raw data and the green plot is raw data minus an estimate of system noise.

The lower plot shows approximate intensity as a function of fringe radius.

These plots are used only as a diagnostic tool to check that the instrument is working properly they are not used for scientific analysis of the data.


A copy of the software used to read the SPECS files is also available with the data.

Access

These data are not available online owing to their large file sizes. A separate word document containing more information about the dataset is also available for download from the provided URL.

Temporal Coverages

• Start date: 1980-12-01 - Stop date: 2012-06-30

Spatial Coverages

Science Keywords

• EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE > AIR TEMPERATURE
• EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC WINDS > UPPER LEVEL WINDS

Use Constraints

This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=Fabry-Perot_Spectrometer when using these data.