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ESR Experiments

Description of the currently available ESR experiment modulation schemes.

Since the ESR is a newer facility than the mainland radars, the current set of ESR experiments contains only the newer kind of modulation schemes. The main ESR modulation schemes, used in the majority of Common and Special Programmes are arc_dlayer, arc_slice, hilde, manda, steffe, and tau0. In addition, two modulation schemes developed by the UK, namely pparc and slopes, have been used in a number of UK Special Programmes.

arc_dlayer - This is essentially the same as the mainland experiment of the same name, discussed in EISCAT's annotated experiments page. However, because the ESR is situated at the top of a mountain and hence can receive cluttering echoes from mountains up to 150km distant, clutter subtraction is needed to extract the data from these low ranges. Analysis of the ESR version of arc_dlayer does not currently seem to be supported by guisdap.

arc_slice - This is essentially the same as the arc1 experiment for the mainland radars, except that clutter subtraction has been applied as described above. The arc_slice experiment is described in more detail in EISCAT's annotated experiments page. Analysis of the arc_slice experiment for the ESR is supported under versions g8.4 and g8.5 of the command-line based version of guisdap, using initiallisation files with the experiment name arc1.

hilde - This is a general-purpose ESR experiment, covering both the E and F regions, intended for use in experiments where the 32m antenna is operated at low elevation and dumps are interleaved with data from the 42m field-aligned dish. This explains the name (hilde stands for High/Low Dual Elevation). Data come from the altitude range 76 to 776 km. Analysis of hilde is supported under versions g8.4 and g8.5 of the command-line based version of guisdap.

manda - This is essentially the same as the mainland experiment of the same name, with the added complication that clutter subtraction is applied to recover the data from the D and E-region ranges. Data cover the ranges from 61 to 495 km though, as with the mainland system, there is a gap in coverage in the lower F-region. Analysis of the ESR version of manda is supported under versions g8.4 and g8.5 of the command-line based versions of GUISDAP.

steffe - The steffe experiment is a general purpose modulation for E and F layer observations, having fully decoded gates from 105-216 and 259-965 km. The basic range resolution is 2.4 km. The steffe experiment also contains a plasma line part, which can be used for calibration purposes. More information about steffe can be found on EISCAT's annotated experiments page. It should be noted that the original versions of steffe used a time resolution of 6.4 seconds (the same as tau0), but that later versions (from 2006) have used a time resolution of 6 seconds. This makes the data easier to work with, but with the inconvenience of requiring a different GUISDAP initiallisation file. Analysis of the 6.4s resolution version of steffe is supported in all command-line based versions of guisdap after g8.3. Analysis of the 6 second resolution version is only supported under g8.5.

tau0 – This was the first general purpose ESR experiment, covering all altitudes from 95 to over 1200 km, using only alternating codes. It has mostly been superseded by steffe, but is still used for some applications. Originally there were three different versions of tau0, with time resolutions of 3.2, 6.4 and 12.8 seconds. However, only the 6.4 second version was extensively used, while attemmpts to run the 3.2s version resulted in a number of technical problems, chiefly in the form of missed data dumps. Analysis of 6.4s resolution tau0 data is supported in all versions of the command-line based guisdap, starting from g8.1. Additionally scripts and setup files are available in the script-based version of guisdap, which can handle the analysis of the tau0 versions with 3.2s and 12.8s pre-integrations.