Instruments:dav

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Davis, Antarctica MF Radar

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Contact Persons

Web Sites

Acknowledgments

The Davis MF radar is operated by the Atmospheric Physics Group of the jniversity of Adelaide, with support from the Australian Research Council. Logistical support is provided by the Australian Science Advisory Committee and the Australian Antarctic Division. The MF radar contributes data as part of the joint TIMED-CEDAR program of the national Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).

Instrument/Model Description:

The Davis, Antarctica (68.60S, 77.97E; ~1 m alt) 1.94 MHz MF radar has been in operation since April 1994. On day 359 of 2001 at 89 km altitude, the apex magnetic coordinates were (64.1, 152.4) degrees. The magnetic inclination and declination angles were 81.7 deg and 21.7 deg. The magnetic local time at 0 Universal Time (UT) is about 0505 MLT. The solar local time (SLT) is UT plus 5 hours and 12 minutes (77.97/15.=5.198). Code 42 (LST-UT) was corrected from 1.E-03 hr to hhmm in Sep 2004.

The original data files are hourly averages of the zonal and meridional velocity in Local Time (LT), which is 5 hours later than UT. Smaples are taken every 2 min, so a possible 30 samples can be had between 05:00:00 LT and 06:00:00 LT. The midpoint is 05:30:00 LT or 0:30:00 UT, or 5:42:00 SLT. Local times have been converted to the mid-point SLT, or 42 min (0.618 hr) are added to the beginning LT hour.

The MF operating frequency is 1.94 MHz, with a peak transmitter power of 25 kW, 40 kW starting in 2004. The radar operates as a spaced-antenna system (Vincent, 1986), relying on coherent echo signals from middle atmosphere ionization. The inter-pulse period is 12.5 and 25 millisec, respectively during the day and night. There are usually 32 coherent integrations during the day and 16 at night, using 256 samples in the full correlation analysis (FCA) of Briggs [1984] with built-in rejection criteria. [ie, want about 2 min or 102.4 sec integration day or night, or 12.5x10-3sec * 32 integ * 256 samples = 102.4 sec and 25x10-3sec * 16 integ * 256 samples = 102.4 sec.]

The height coverage is 50-100 km during the day or night at Davis. The pulse width is 30 microsec, giving a height resolution of 4.5 km assuming a simple rectangular wave pulse [range of heights illuminated by the wave pulse = velocity of light * pulse-width / 2 = 3x10**8 m/s * 30x10-6s / 2 = 4.5 km]. However, the height range provided is every 2 km between 50 and 100 km starting in 2003, and 50 and 98 km earlier.

Starting in 2002, the data are also contributed to the joint TIMED-CEDAR program of the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF). The original hourly velocities are converted to harmonic analyses in UT over sliding 4-day intervals. The Mesosphere-Lower Thermosphere Radars (MLTR) organized for the TIMED-CEDAR program provide horizontal and sometimes 'vertical' neutral winds to the processing center at the University of Colorado. Summary plots from several types of MLTRs in the TIMED-CEDAR program and references for the instruments, analyses using the radars, and comparisons with other satellite or ground-based instruments can be found at:
[/instruments/mltr.html ] (click on 'Data Services', then on 'Instruments', etc)

The harmonic analyses are also available at that site, or from the University of Colorado at:
http://sisko.colorado.edu/TIMED/data/MLTR/

References

Briggs, B. H., The analysis of spaced sensor records by correlation techniques, MAP Handbook, Vol. 13, 166-186, 1984.
Fraser, G., Partial reflection spaced antenna wind measurements, MAP Handbook, Vol. 13, p 233, 1984.
A. H. Manson, C. E. Meek, and R. A. Vincent, Comparison between referenced atmosphere winds and radar winds from selected locations, Adv. Space Res., Vol 10, No. 12, pp 233-244, 1990.
A. H. Manson, C. E. Meek, R. Schminder, D. Kurschner, R. R. Clark, H. G. Muller, R. A. Vincent, A. Phillips, G. J. Fraser, W. Singer, and E. S. Kazimirovsky, Tidal winds from the MLT global radar network during the first LTCS campaign -- September 1987, J. Atmos. Terr. Phys., 52, pp 175-183, 1990.
A. H. Manson, C. E. Meek, E. Fleming, S. Chandra, R. A. Vincent, A. Phillips, S. K. Avery, G. J. Fraser, M. J. Smith, J. L. Fellous, and M. Massebeuf, Comparisons between satellite-derived gradient winds and radar-derived winds from the CIRA-86, J. Atmos. Sci., 48, pp 411-428, 1991.
A. H. Manson, C. E. Meek, S. K. Avery, G. J. Fraser, R. A. Vincent, A. Phillips, R. R. Clark, R. Schminder, D. Kurschner, and E. S. Kazimirovsky, Tidal winds from the mesosphere, lower thermosphere global radar network during the second LTCS campaign: December 1988, J. Geophys. Res., 96, pp 1117-1127, 1991.
A. Phillips and R. A. Vincent, Radar observations of prevailing winds and waves in the southern hemisphere mesosphere and lower thermosphere, Pure and Applied Geophys., 130, pp 303-318, 1989.
R. A. Vincent, T. Tsuda and S. Kato, Asymmetries in mesospheric tidal structure, J. Atmos. Terr. Phys., 51, pp 609-616, 1989.
Vincent, R. A., Hardware requirements: A new generation partial reflection radar for studies of the equatorial mesosphere, MAP Handbook, Vol. 20, p 85, 1986.
Vincent, R. A. and D. Lesicar, Dynamics of the equatorial mesosphere: First results with a new generation partial reflection radar, Geophys. Res. Lett., 18, 825-828, 1991.

Summary Plots of Hourly Winds for TIMED from Davis, Antarctica MF Radar


-Revised 09 Sep 2004 by Barbara Emery