Sondre Stromfjord Digisonde Drift Measurements
The Digisonde (DISS) located at Sondre Stromfjord, Greenland (67.0N,309.05E) and operated by the University of Massachusettes Lowell Center for Atmospheric Research, for Air Force Research Laboratory Hanscom AFB, has produced ion velocity measurements and electron density profiles since 1986. The data are originally collected in local magnetic coordinates, and then converted to geographic coordinates using the declination angle of -41.2 for an altitude of 0 km.
The Digisonde generally operates in a 15 minute cycle mode, where the first 2-3 minutes an ionogram is recorded followed generally by 1-2 minutes of drift measurements, with the remaining 10-12 minutes idle. Sometimes the cycle time is 5 minutes. The range of altitudes is about 200-450 km, where the mean for the 1993 data was set to 250 km.
Digisondes transmit HF radio waves illuminating a large ionospheric area of several hundred kilomaters diameter over the sounder. Radio waves are sent up and reflected off orthogonal surfaces. Each reflection point is considered to be a separate source and has associated with it a line- of-sight (los) Doppler velocity measurement. Making the assumption that the main contribution to the measured Doppler shifts results from the uniform horizontal bulk motion of the plasma, the los velocity and source location are used to calculate the velocity vector by least squares fit.
The drift mode resulted in up to a maximum of 64 sources in a single integration period of 5 seconds. One minute data is obtained where the error bar is the average of the standard deviations from 12 5-second integrations, while the value of each velocity component is the median from a further velocity distribution found using all the data points in the entire one minute period. The 1 minute results were taken and reported every 15 minutes.
Summary plots of the ion drifts towards geographic East, North and up are plotted for 20 days at a time. Error bars are shown as dotted lines. There are very few data gaps for this period of 1993 submitted by Vadym Paznukhov, firstname.lastname@example.org.
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Fukui, K, J Buchau and C E Valladares, Convection of polar cap patches observed at Qaanaaq, Greenland during the winter of 1989-1990, Radio Sci, 29, 231-248, 1994.
Reinisch, B W, T W Bullett, J L Scali and D M Haines, The high latitude Digisonde measurments and their relevance to IRI, Adv Space Res, 16, 17-26, 1995.
Scali, J L, B W Reinisch, C J Heinselman and T W Bullett, Coordinate Digisonde and incoherent scatter radar F region drift measurments at Sondre Stromfjord, Radio Sci, 30, 1481-1498, 1995.
Summary Plots for Sondre Stromfjord Digisonde Ion Drifts
- Jan 01-Jan 20, 1993 All data for this period
- Jan 21-Feb 09, 1993 All data for this period
- Mar 02-Mar 21, 1993 All data for this period
- Mar 22-Apr 10, 1993 All data for this period
- Apr 11-Apr 30, 1993 All data for this period
- May 01-May 20, 1993 All data for this period
- May 21-Jun 09, 1993 All data for this period
- Jun 10-Jun 29, 1993 All data for this period
- Jun 30-Jul 19, 1993 All data for this period
- Jul 20-Aug 08, 1993 All data for this period
- Aug 09-Aug 28, 1993 All data for this period
- Aug 29-Sep 17, 1993 All data for this period
- Sep 18-Oct 07, 1993 All data for this period
- Oct 08-Oct 27, 1993 All data for this period
- Oct 28-Nov 16, 1993 All data for this period
- Nov 17-Dec 06, 1993 All data for this period
- Dec 07-Dec 26, 1993 All data for this period
- Dec 27-Dec 31, 1993 All data for this period
-Revised 23 Oct 2000 Barbara Emery