Overview

Measurements of cloud base height and vertical visibility using pulsed infrared (910 nm) diode laser LIDAR technology. The instrument can detect up to three cloud layers simultaneously.

Data Details

Measurements taken in the standard measuring mode, where the CL31 ceilometer digitally samples the return signal every 67 ms from 0 to 50 microseconds, provide a spatial resolution of 10 m with data-averaged messages received every two seconds. The reporting interval is 16 seconds.

Data are saved in 7-bit US-ASCII format files of type .DAT through the Vaisala software CL-VIEW then decoded offline into files of type .xlsx using the same software. Refer to Vaisala Graphical User Interface for Ceilometers CL-VIEW User's Guide (software manual) or Vaisala Ceilometer CL31 User's Guide (instrument manual). Both .DAT and .xlsx data files are provided in the DAP, along with a graphical presentation (.png file) of the cloud intensity versus altitude over 24-hour periods.

IMPORTANT NOTE: Graphics are for illustrative purpose only and may include invalid data.

The description provided in "Primary Measurements/Variables" refers to the .xlsx type. For explanatory purposes, a typical data file of type .xlsx also is attached.

Note that each file (both .DAT and .xlsx) contains 24-hour data—unless an instrument failure occurred. In this case, there may be two partial files per type (or more in cases of multiple failures within 24 hours) that contain the data collected prior and after the failure, respectively.

• Instrument Location: Wasco, OR
• Latitude: 45˚ 35.400’ N
• Longitude: 120˚ 40.317’ W
• Elevation (meters): 442 m

Data Quality

Automated quality control (QC) is performed via the instrument software and already is applied to the data provided to the DAP. These data files contain error values (column called “status” in the .xlsx files). A "0" signifies that no error has happened. Definitions of the different error groups are provided in the Vaisala Ceilometer CL31 User's Guide* (PDF attachment).