Statically mounted polarsondes at Macquarie Island

Full description

This dataset comprises measurements of backscatter intensity from two polarimetric backscatter sondes mounted statically on masts at Macquarie Is. from January 2017 to June 2017.
One is located on the anemometer mast on the isthmus, about 9.5 m above the ground, and the other on the transmitter mast on Wireless Hill, at a height of about 2.5 m.
The instruments emit polarised light horizontally into the atmosphere in a SSE direction. Each has two channels, with different polarisations and/or different wavelengths, and each channel has two photodetectors, one with the analyser polariser oriented parallel to the emitted polarisation, and the other with analyser oriented perpendicular.

Anemometer mast: To March 2017;
Channel 1, horizontally polarised light emitted, 470 nm
Channel 2, emitted light polarised 45 degrees to horizontal, 470 nm
From March 2017;
Channel 1, horizontally polarised light emitted, 470 nm
Channel 2, horizontally polarised light emitted, 650 nm

Wireless Hill mast:
Channel 1, horizontally polarised light emitted, 470 nm
Channel 2, emitted light polarised 45 degrees to horizontal, 470 nm

The data are in ASCII text format, recorded once per second and written to hourly log files. Each day at 0000Z these are archived to a compressed file (tar + gzip), with the date of the compressed file creation being included in the filename of the gz file.

A quirk of the timing is that a second or two of data from the start of the day are included with the data for the previous day. Also a few seconds of data are generally not recorded at the start of each day due to the computational overhead of the archiving process.

An example line is
2017/03/05 01:59:46 t, 4598358, L, 0.12814012, 0.05185896, 0.40470508, 99.6, C, 0.08772506, 0.06333281, 1.38514388, 99.0, B, 9.0

The data are as follows;
Date and time (UTC), "t", seconds elapsed, "L" (channel 1), co-polarised signal, cross-polarised signal, channel 1 depol, LED current (mA), "C" (channel 2), co-polarised signal, cross-polarised signal, channel 1 depol, LED current (mA), "B" (power supply), supply voltage.

Files with name starting "PS-20*" are from the anemometer mast installation and those starting "PS-WH-20*" are from Wireless Hill.

Lineage

Progress Code: completed

Statement: In the data the depolarisation (depol) recorded is the ratio of the cross-polarised to co-polarised signals. The value given is meaningless because the static mounted polarsonde has a window which introduces a background signal. (This is in contrast to the balloon mounted version which has no window.) In addition there is a signal background due to pick-up of the pulsed current to the LEDs, that also has to be accounted for. These backgrounds have been measured, but because of dirt, water stains, raindrops etc on the windows the background changes. It is best to take the global minimum of a day's or a week's worth of data for a particular channel as the background. Cleaning of the windows is infrequent.

Notes

Purpose
The data are primarily to identify the thermodynamic phase of cloud particles in the atmosphere, including water (liquid or ice) and aerosols, via their shape which determines the polarisation of the backscattered radiation.