Most of the downloadable files from the DHL (Durmid Hill Laser strainmeter) instrument are 5-minute data, stored as ASCII files compressed with bzip2. The data are in datalogger counts (read across and down), after a header which looks like (for example)
DHL LSM HDR 2003 122 0 45 0 2003 203 23 55 0 23607. STRN A01
300. .0 .0 2 0 0 .00
Strain measured along azimuth 4.3 deg W of N between 33.38986N 115.78823W and
33.39457N 115.78866W (524.1 m, sloping 0.6 deg). LSM HDR and RCLP are measured
change in length, 0.00943 nanostrain per count. RCLP is low- pass filtered
(500 s RC filter), extension -; HDR is extension +. N and S FOA 1 and 2 are
optical- anchor measured displacements of the N and S end points, 0.007075
equivalent nanostrain per count, unfiltered.
Approximately-corrected strain is HDR - 0.75*(NFOA+SFOA).
THESE DATA ARE RAW DATA AS RECORDED AND SHOULD BE INTERPRETED WITH
CARE, AND WITH UNDERSTANDING OF THE PRINCIPLES OF THE INSTRUMENT
which means that the data consists of 23607 terms, with a sample interval of 300 seconds, from 2003:122:0:45:0 (UTC) through 2003:203:23:55:0. The channel name is LSM HDR, with the gain described in the accompanying notes.
The files currently available are: (1) strain, (2) a filtered version of the strain, (3) the North anchor, (4) another version of the North anchor (different optical fibers), (5) the South anchor, (6) another version of the South anchor (different optical fibers), (7) the air temperature, (8) the air pressure, (9) the ground temperature at 1 m depth, (10) the solar radiation, (11) the wind direction, and (12) the wind speed.