Readme.txt for the Ceilometer-estimated PBL-height format
Version-1: 02/11/2016

The "yyyymmdd_PBL_CL.dat" files include the PBL-top or PBL-height calculated from the Ceilometer (CL-51)
at CCNY-site (Geolocation: 40.821 deg North, -73.949 deg West), New York City. 
It usually runs 24-hr/7day without the operators.

Time resolution: 3 or 10-min average
Range resolution: 10-meter
Time label: Local time (Eastern Daylight saving time in summer (EDT), or Eastern Standard Time (EST) in Winter).

Algorithm*:Wavelet transform analysis of the attunated backscatter profile gradient along the height
           Define the PBL-top where the gradient of atmospheric attenurated backscatter is the biggest. 

Data format:
1st column: date (yyymmdd)
2nd column: local time (hour:minute:second), local time
3rd column: local decimal time in hour,local time
4th column: PBL-height or PBL-top in kilometer (-99 filled value)

5th column: QualityControl-flag for the PBL-height (2-good, 1-fair, -1-poor or none estimate due to the low clouds)
            QC=2 Under the clear sky (good consistency between the two methods)
            QC=1 Low clouds at 0.6-2.0 km or the PBL-top relative difference > 20% between the two methods
            QC=-1 none estimate due to the low clouds z<0.6 km
			
6th column: Low-cloud height in kiometer (orginated from the CL-51 product, -99.0 for the clear sky)
            The PBL-top is calculated under the cloud base (re-adjusted from the oringal cloud height).

Note: There are no estimate of the PBL-height or PBL-top when the low clouds exist below 0.6-km or raining sky.

If any questions or comments, please contact Yonghua Wu at 212-650-8330 or email: yhwu@ccny.cuny.edu.

*Reference for the algorithm:
 C.-M. Gan, Y. Wu, B. Gross, F. Moshary, S. Ahmed, Application of active optical sensors to probe the vertical structure
   of the urban boundary layer to assess anomalies in air quality model PM2.5 forecasts, Atmos. Env. 45, p. 6613-6621, 2011.
   http://www.sciencedirect.com/science/article/pii/S1352231011009459