UND Ceilometer README

Author: 
 Laura S. Leo
ORCID: 
 http://orcid.org/0000-0003-4103-6862
email: 
 lleo1@nd.edu
Institution: 
 University of Notre Dame 

1.  Dataset 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.
 - Time period covered: 2017/04/28 - 2017/06/19
 - Physical location:
		PT-TM06/ETRS89: 33922.687, 5007.214
		WGS84 Lon/Lat:7°44'15.04"W, 39°42'45.66"N
		Elevation: 294.298 m
 - DOI: https://doi.org/10.5065/D6TQ609X

2.  Instrument  
    Vaisala Ceilometer CL31

3.  Data Collection and Processing
    Measurements taken in the standard measuring mode, where the CL31 ceilometer digitally samples the return signal every 67 ms from 0 to 50 microseconds,
    providing 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 off-line into files of type *.txt.
    Automated quality control (QC) is performed via the instrument software and already applied to the data provided here. 

4.  Data Format
	-Data file structure: column delimited ASCII. Each file contains 24-hours of data collections
	-File name represents the date of collection. For example: A7060200.txt represents data collected during the year 2017, month 06, day 02
	-Time is UTC
	-List of parameters is given in the file header. Date included in the header represents the date that the automatic QC procedure was applied to the data. 
 
	-Description of flags, codes used in the data: 
		column n.2 represents the STATUS of detection as follows:
			0 = No significant backscatter
			1 = One cloud base detected
			2 = Two cloud bases detected
			3 = Three cloud bases detected
			4 = Full obscuration determined but no cloud bases detected
			5 = Some obscuration detected but determined to be transparent
			/ = Raw data input to algorithm missing or suspect
		Depending on the status of detection (column n.2 ), column n.3 represents :
			a)Lowest cloud base height if STATUS=1,2,3
			b)Vertical visibility if STATUS=4
			c)/// if STATUS=0 or 5